Document vB3YMzGGyvBqnkJa5XnZzN5MY

TP ENVIRONMENTAL LEAD EXPOSURE IN FINLAND A study on selected population groups by CLAES- HENRIK NQROMAN Institute of Occupational Health Helsinki, Finland Academic dissertation To be publicly discussed, by permission of the Medical Faculty of the University of'Helsinki, in Auditorium XII on May 29, 197.5, at 12 o'clock noon. Helsinki 1975 i N 27041 ISBN ,951-99053-6-7 Helsingin yliopiston monistuspalyelu 19.75 DUP040007218 ABBREVIATIONS Pfa-B Pb-U Pb-H Pb-A: ALAD ALA-U CP'-U PBS Hb PCV RB.C EDTA Blood lead concentration Urinary lead concentration lead content in hair . Concentration of air-suspended particulate lead Erythrocyte 5-aminolevulinic acid dehydratase Urinary <5-aminolevulinic acid concentration Urinary coproporphyrin concentration Porphobilinogen Hemoglobin concentration Packed blood cell volume Red blood cells Ethylenediamine tetra-acetate DUP040007219 A 'J A-- Cl j i II 5.4.1. Lead in blood ........................ ..................... -- 28 5.4.2. Erythrocyte A-ALAD activity >...............................29 5.4.3. Hematocrit value ............................ 29 5.4.4. Hemoglobin concentration 29 5.4.5. Dustfall lead .......................... 30 5.4.6. Lead in air ................. 30 5.4.7. Lead in food and beverages 30 5.5. Statistical treatment ....................... . . .......... 33 6. ENVIRONMENTAL LEAD EXPOSURE OF A RURAL POPULATION: A study on dietary intake, ex posure from ambient air, and blood lead 1evels ...... ................... ... 6.1. Introduction.................................... 6.2, Material and methods 6.2.1. Blood lead survey fi.R.2. Diet survey ....................................... 6.2.3. Lead in ambient air.............................. 6.3. Results ........................................................ 6.,3.1. Lead in ambient air ,,---------- ------------.... 6.3.2- Daily lead intake ........................... . 6.3.3. Blood lead survey -------------------------------..... 6.4, Discussion .................. 6.4.1. Blood lead levels ........................................ 6.4.2. Dietary lead intake .......................... 6.4.3. Lead in ambient air................................. 6.5, Conclusions ................... 34. 34 34 34 38 40 41 41 42 45 47 47 50 51 .51 7. BLOOD LEAD LEVELS AND ERYTHROCYTE &-ALA DEHYDRATASE ACTIVITY IN SELECTED POPULATION GROUPS IN HELSINKI ........................ 7.1. Introduction 7.2. Material and methods ..... ................. . 7.2.1, Aerometric sampling --............. 7.2.2. Selection of population groups ............. 53 53 55 55 56 . ../lit DUPO40007220 CONTENTS ABBREVIATIONS 1. INTRODUCTION ............................. 1.1. Today's lead problem .................. ,............... I i 2. LITERATURE REVIEW ..................... 2.1. Natural sources of lead exposure ................ 4 4 2.2. Man-made sources of lead exposure ........... $ 2.3. Environmental exposure levels ---------2.3.1. Lead in ambient air .................... 7 7 2.3.2. Lead in drinking water ..............----- .... 8 2.3.3. Lead in food ................................................................. 9 2.4, Metabolism of lead in man 13 2.4.1. Absorption 11 2.4.2. Distribution --------- 12 2.4.3. Excretion ...... ................... . --13 2.5, Concentrations of lead in human tissues ..... 13 2.5.3. Lead in blood 34 2,5,2. Lead in hair 16 2.6, Parameters reflecting lead absorption ....... 16 2.7, Parameters reflecting lead effects .......... 18 3. OBJECTIVES OF THE PRESENT INVESTIGATION ...... 21 4. GENERAL DESCRIPTION OF THE MATERIAL..,.,.,. 22 5. METHODS: GENERAL ........................................ 25 5.1. Assessment of environmental exposure ............. 25 5.1.1. Sampling of dustfall lead ................... ............... 25 5.1.2. Sampling of air-suspended particulate lead 25 5.1.3. Assessment of dietary lead intake 26 5.2. Choice of parameters of absorption and effect ..... ..................................................................... .27 5.3. Collection of biological samples ............... 27 5.4. Analytical methods .......... ........................... 28 .../II DUP040007221 Ill.. 7.2.3. Collection of biologicaldata ......-------- >. 7.2.4, Analytical methods ............................. 7,3, Results .......................... .......____ 7.3.1. Lead in air ------- ---------- . 7.3.2. Lead in blood 7.3.3. Erythrocyte A,,ALAD activity.......... 7.4. Discussion ___ .... 7.5. Conclusions 59 59 61 61 63 65 67 70 8. BLOOD LEAD LEVELS AND ERYTHROCYTEA-ALA DEHYDRATASE ACTIVITY IN RESIDENTS AROUND LEAD EMITTING INDUSTRIES ...................... 8.1, Introduction.................................................. 8.2, Material and methods ...............................,.... 8.2.1, The Tikkurila area ...... ........................ 8.2.2, Target population ..... 8.2.3, Methods ____ _................................ . 8.3, Results 8.4, Discussion .......................................... 71 71 72 72 72 74 75 81 9. COMPARATIVE RESULTS ------------- -------- S3 IP. 10.1. 10.2. 10.3. 10.4. GENERAL DISCUSSION............................ Validity of the Pb-B assay ......... Blood lead levels in Finland........... The ALAD assay in population studies Preventive needs for Finland in the light of the present study 88 88 89 90 92 11, SUMMARY,,........................................ 95 12, ACKNOWLEDGEMENTS _____ 98 13, REFERENCES........................ 100 DUP040007222 2 in the areas of epidemiology and toxicology.. Thus, lead poison ing affecting children in the U.5.A. has introduced what is pro bably the most urgent problem in regard to the health hazards of lead. An association between pica and lead poisoning in children was reported by Ruddock as early as in 1924. It has now been es tablished that the ingestion of flaking paints, crumbling plaster, and putty with a lead content induces the clinical poisoning of children living in decaying building. Only the case-finding cam paigns conducted in some American cities have revealed the tragic extensiveness of childhood poisoning. It has been stated that between 1 to 2 percent of the slum-dwelling children in New York and Chicago have unsuspented lead poisoning (Chisolm 1971, Guinea 1971). According to an estimate, the concentration of lead in the bipod of some 250,000 children annually exceeds safe limits (Moore 1970}.' By now., it has become common knowledge that environmental lead pollution has been increasing during the entire period of industri alization, and that this is a result of neglect in the supervision of industrial discharges, and the outcome of decomposition of in dustrial products (NAS 1972, WHO 1973 , Waldron and Stofen 1974). Most of the increase has been attributed to the combustion products of lead alkyls, used as anti-knock additives in gasoline (NAS 1.972, WHO 1973, Waldron and Stofen 1974),The lead content of the atmosphere in several metropolitan areas has increased to a level that is high enough to affect the absorption of lead by the inhabitants and especially those who are exposed to exhaust gas (Hofrenter et al. 1961, Lydwig et al. 1965, Thomas et al.'1967, Horiuchi 19.70, Lehnert et al. 1970;), It has similarly been shown that primary and secondary lead smelteries may subject the surrounding popula tion to lead exposure which markedly exceeds that affecting the population in general, resulting in increased lead absorption (Oyanguren and Pere? 1966, Djuric et al. 1971, 1972, Rordman et al. 1973, Kerin Z 1974, Martin et al. 1974), DUP040007223 1 ,, INTRODUCTION 1.1 .Today's lead problem From the historical standpoint, it is probable that Nicander has the best claim to the discovery of a causal connection between lead and the symptoms of lead poisoning in the second century B.C. Al V though this honor has often been credited to Hippocrates (170 8.C.) i i [Aub 1926, Hunter 1969) this has.been disputed by students of the medical history of lead .(.Waljdron 1973), In the first century A.D,, Pliny noted that lead poisoning frequently occurred among ship builders; in the sixteenth century, Paracelsus termed lead pois oning "the miners'" disease", and in 1839 Tanquerel des Planches published an excellent study oh 1200 cases of the disease (Hunter 1969), During the second half of the nineteenth century, and the first decades of the twentieth, the incidence of occupational lead poisoning was extremely high, and a fatal outcome of such poisoning was'no rarity (WHO 1973, Hernberg 1975), Considerable improvements in hygienic conditions in industry have brought about a change in the character of occupational lead poisoning, despite the continu ously increasing industrial use of lead; nowadays, cases are seldom severe, and the incidence has decreased significantly (Hernberg 1:975), One is traditionally apt to associate lead with the conception of manifest lead poisoning, usually of occupational origin. Although l the significance of lead as an occupational poison is still accorded major importance, since the mid-sixties both the directing of re search and scientific discussions concerned with the health impli cations of lead have been increasingly dominated by aspects of public health. This has been the consequence of extensive studies relating to environmental pollution, along with the progress made DUP040007224 4 berg and Nikkanen 1970, Stuik 1974, Seppalainen et al. 1975). To date, the significance of these subcTinical effects to roan's health is unknown. Nevertheless, the governments of several countries, in cluding West Germany .and Sweden, have already decided substantially to lower the maximum content of lead in gasoline with a view to re ducing, the environmental exposure (Campell 1973):. Consequently, the current situation is more complicated than ever; although the significance of the subclinical effects of lead to man's health is still obscure, the presence of Such responses must, from the standpoint of public health,,be considered as undesirable for as long as they have not been proven un-deleterious. For pro tection of the most susceptible, individuals of the community, those groups of the general population which may be subjected to undue environmental exposure should be morsitored, and the total exposure of these risk groups determined by the employment of screening measures that are as sensitive as possible.. 2.. LITERATURE REVIEW 2.1. Natural sources of lead exposure Lead, a ubiquitously-distributed metal, has always been present at natural levels, that is at levels unaffected by man's activities. The average lead content in the earth's crust is about 16 mg/kg, with a variation from .6 to 20 mg/kg depending p.n the type of sub stances Soils also have a content of about 16 mg/kg ,(.de Treville 1964). The ubiquity of lead further entails its presence in the atmosphere, the sources being: silicate dust from natural soils, volcanic halogen aerosols, volcanic silicate smoke, forest fire smoke, aerosolic sea salts and meteoric smoke (Pattersson 1965) . According to Pattersson's estimates, the contribution from these natural sources results in an average concentration in the air of DUP040007225 V t 3- The detection of a number of subclioical lead-induced effects has . also made a significant contribution to making .attitudes more ori ented towards the domains of public health. The development of more sensitive techniques has enabled the detection of subclinical neuropathy, even v/hen the Pb-Bhas never exceeded the commonly ap plied safety limits in industry (Seppalainen etal. 1975), The partial inhibition of ALAD activity has been demonstrated at blood- -lead levels that are characteristic of the general population (Hernberg and Nikkanen 1970, Secchi et al, 1971, Lauwerys et al, 1973, Nordman et al. 1973). The significance of the partial in hibition of erythrocyte ALAD activity is unknown. Several author ities have regarded it as unimportant to health (Kehoe 1971, Ziel- huis 1974); nevertheless, it has been demonstrated that the in hibition of erythrocyte ALAD activity correlates with a corres>- spending inhibition of the ALAD activity in other animal and human tissues, such as liver, brain, kidney and bone marrow .{.Gibson and Goldberg 1970, Millar et al. 1970, Secchi et .al. 1974). Recent reports have indicated that the accumulation of protoporphyrin IX in erythrocytes .begins at Pb-Blevels as low as 25 to 30 eg/ 1Q0 ml in women, and have further evidenced that women have a higher susceptibility to lead than have men in regard to proto- pprphyrin IX (Stuik and Zielhuis 1974, Stuik 1974, Roels et al. 1975). 'i f Briefly, it may be said that the changed attitude towards lead problems arises from the circumstance that several groups of the general population are known to be exposed to environmental lead i levels-that raise the amount absorbed. However, no agreement has been reached as regards either the concentration of lead in blood which can be considered as acceptable for the general population {EPA 1972, Zielhuis 1974, Waldron 1974), or the concentration of > h i-. lead in the ambient air at which the lead absorption begins to rise (EPA 1972, Tepper and Levin 1972). New and more sensitive I methods have disclosed responses to low lead concentrations for merly regarded as consistent with a non-effect apprehension (Hern- DUP040Q07226 :v j v*:^ !W--: V . i ', ..- ---.1 -V4 `f: &"'A j ; -- Vv.;.! 6 in 1923; since then, the use of alkyl lead additives has under gone an explosive increase, as is evident from the calculations of Murozumi and his colleagues, who estimated a combustion of alkyl lead compounds in the Northern hemisphere in 1933 of about 10.000 tons, against some 300.000 tons in 1966 (Murozumi et al. 1969). The lead alkyls are responsible for an approximative 98? of the total lead emissions in the U.S.A. (NAS 1972). The pollu tion resulting from lead alkyls, is even reflected in a rise in the lead content of the icecaps of Greenland (Murozumi et al.1969). The air is cleaned by gravity, aggregation and precipitation, with rain acting as the main cleaner and thus contributing to the lead content of waters and soil. Accumulation takes place in plants, particularly in the leafy portions. This implies that leafy veg etables thereby provide lead with an opportunity to enter herbi vorous animals and man (NAS 1972, Hernberg 1975). Most investi- . gators claim that lead in the soil is taken up by plants only in an extremely small proportion, and that the chief source for up take by plants is rainfall (NAS 1972). It fallows from this that exceptional concentrations of lead in the air, in water and in food may be found in certain areas which are subjected to high traffic-density or industrial emission* Some conditions may en hance the exposure of food and, water., such as the use of lead piping and lead-lined tanks, which may contaminate tap-water to even a dangerous extent (Bacon et al. 1967, Beattie et al.. 1:97.2 b ); furthermore, the firing of earthenware qlaze at tempera tures that are too Tow may allow of the release of lead into acidic foods and beverages, and constitute an important hazard to the public health (Harris and Elsea 1967, Klein et al,. 1970, Ylikahri and Toivonen 1973).. The production of illicit whiskey, with leaded soldering or discarded automobile radiators utilized as condensers, has Caused a great deal of concern, especially in the U.S.A. ( Hughfss 1966, Palmisanb et all 1969, WAS 1972). Flaking paints, perishing plaster, and the putty found in decay ing buildings, makej up a pediatric problem of vast dimensions in the U.S.A., where iin several states the legislation pertaining DUP040007227 5 0,0005 r 0.00Q6 jig/ui3', and In surface waters of around 0.0005 mg/ kg. These estimated figures gain .support from investigators of marine and arctic atmospheres (Egorov et al. 1970, Murozumi et al. 196:9. Chow et al . 1969) and from studies .of the lead content of ice sheets in the Northern polar regions (Murozumi et al.. 1969) and deep waters of the Mediterranean and the Pacific (Tatsumoto and; Patterson 1963, Chow and Patterson 1966). However, in a fttan-made environment the contribution from natural sources is so minimal that it lacks importance. 2.2. Man-made sources of lead, exposure In this context, no full account needs to be given of the sources of exposure; these have been reviewed in a number of exhaustive monographs in recent years (Ziegfeld 1964, NAS 1972, WHO 1973, Waldron and Stofen 1974, Hernberg 1975), and only the most perti nent of these will be touched upon here. Man's total exposure is constituted by a background exposure derived from air, food and water, which is dependent upon geographic, socioeconomic and other factors, and a probable additional exposure ..arising from occupa tion, or from the ingestion of substances with a lead content. Ambient air, soil and water are polluted as a consequence of in dustrial activity, through both manufacturing processes and the decomposition of industrial products. Fly-ash from the burning of coal in power stations, steel works and factories contains up to approximately 5 per cent of particles a few microns in diame ter. These have a lead content of about 100 mg/kg (Patte.rss.on 1965). It is well known that the emission from lead-processing industrial undertakings such as secondary lead smelting plants, .storage battery plants, and even tetraethyl-lead manufacturing plants, pollutes the surrounding air, watercourses and soil(WH0 1973). Of all industrial products, the alkyl lead compounds are regarded as being the most important in regard to environmental pollution. Tetraethyl lead was introduced as an antiknock agent DUP040007228 s very high, and may .exceed 20 yg/m3 (Ludwig et al, 1965, Horiuchi . 1970). Lead concentrations even higher than this have been meas ured in the surroundings of primary and secondary lead smelters (Fugas et al. 1972, Martin et al. 1974). Unfortunately, the re sults reported by different authors are not easily comparable, since great differences exist between the kinds of sampling equip ment , the procedures of sampling, and the analytical methods used. The first step towards international standardization of air sampl ing techniques has been taken by the Commission of the European, Gommunities (CEC 1972), Although the lead concentrations that prevai1 at many work places are often substantially higher than those in outdoor air ,the prob lem involved is not comparable to that arising from outdoor air, pollution, as it concerns only healthy adults who are exposed for 40 hours weekly; exposure for the general population, however, is continuous and also concerns pregnant women, children, old people and disabled persons. Nevertheless, occupational exposure represents an additional load for many people. 2.3.2. Lead in drinking water As a rule, the daily intake from water is very much lower than that from food (NAS 1972), The acceptable limit for lead con tent in drinking water has been fixed, by both WHO (Geneva 1963) and the US Public Health Services, at SO yg/1. Although most of the values reported have been below this limit (McCabe et al, 1970, WHO 197.3), extremely high values have also been established; these have even resulted in manifest lead poisoning (Gajdos and Gajdos-Torok 19.72, Beattie et al. 1972 a. Bacon et al, 1967, Heusgem and Oe Graeve 1972), The hazards to health that arise from drinking domestic water con taminated by lead have resulted in serious debate, especially in DUP04Q0D7229 7- to the use of lead-pigment indoor paints has been defective down . to the nineteen-seventies (NAS 1972). The use of indoor paints with a lead content exceeding 2% was prohibited in Finland in 1929. Finally, the extensive use of lead in industry subjects a large proportion of industrial workers to occupational exposure. The degree of exposure is largely dependent upon the nature of the pro cess, the elimination techniques applied, and the general hygienic conditions of the workplace. It has recently been estimated that approximately 5CG to 1,000 workers in Finland are continuously ex posed to the risk of occupational lead poisoning; moreover, by law, an additional 20,000 workers should receive regular health examinations by reason of exposure to lead (Tola and Hernbe'rg 1975). In the assessment of man's total lead exposure, each of the sources of exposure must be taken into account, and it has to be borne in mind that .exposure to One of the sources may decrease the level of tolerance to another source. 2.3. Environmental exposure levels 2.3.1, Lead in ambient air On repeated occasions, it has been demonstrated that the concentra tion of lead in ambient air correlates with traffic density (NAS 1972, WHO 1973). For the most part, rural monthly and annual con centrations are well below 0,5 pg/m3 (dost et al. 1972, GE.C 1972, Tepper and Levin 1972). The yearly and monthly means in resident ial areas of small and medium-sized cities in the U.5.A., and also 3 in Europe* are usually around 1 ug/m ; in large cities., the figures are from 1 to 2 pg/m3 , and rarely exceed 3 pg/m3 , as for in stance in Los Angeles (Ludwig et al, 1965, Horiuchi 1970, Tepper and Levin 1972 , Fugas et al. 1972, CEC 1.972, NAS 1972, Choyin et al, 1,972). Short time values in busy metropolitan areas are often DUP040007230 values calculated for Japanese adults have amounted to about 230 to 320 pg (Horiuchi 1970). A common and conspicuous feature of these reports is the wide range indicated. Wide variations occur in the methods of sampling and in the analytical methods, with con sequent reduction in the reliability of any intercomparison between results. For natural reasons, plants are exposed to airborne lead pollution. Although it would seem that airborne lead could make only a slight contribution to the edible portions of most plants that grow in the immediate proximity of highways, the content of the leafy portions Of plants is strongly correlated to the concentrations of lead in air (NAS 1972). From the aspect of human exposure, leafy vegeta bles growing in polluted areas are of particular importance, but it has been shown that roughly SOX of the lead is removable from the Iteafy portions by washing (NAS 1972). High values for lead content have been found in plants growing in areas of exceptional lead contamination resulting from lead mining and refining (Good man and Roberts 1971, Djuric et al. 1971,, Kerin 1971 )> No enrichment of lead occurs in the food chains of practical im portance to man, and no clear pattern can be derived from available studies in regard to which kinds of food have the highest lead content. Fresh meat, fruit, vegetables, and canned or bottled foods have displayed rather high levels of lead content, although these have only rarely exceeded 1.0 mg/kg (Lehnert et al. 1969, Horiuchi 1970, Tolan and Elton 1972). Milk deserves special attention, by virtue of its making up a large proportion of infants1 diet. Several investigators have reported considerably higher levels of lead in canned milk products than those ih human breast or cow ..miIk (Lamm et al. 1973, Mitchell and Aldous 1974). Lead in breast milk may be of importance if the mother is subjected to occupational lead exposure", the elevated blood-lead level will as a conse quence increase both the prenatal exposure and the lead excretion via milk (Task .Group on Metal Accumulation 1973), Breast milk seems 9 great Britain, where lead piping is common in many residential districts. Furthermore, it has been shown that the acidity and' the salinity of water influence the degree of plumbosolvency. Thus, evidence exists that soft water with a low pH, i.e. below 7.8, dis plays a higher lead content in over-night tap-water than does hard water of less acidity (Anonymous 1967, Wilson 1966,1967, Reed and Tolley 1967, Crawford and Morris 1967, Heusgem et De Graeve 1972, Goldberg 1974, Hem et Durum 1973). Few data indicate any kind Of .chemical transformation of lead in water which would correspond to the inethylation of mercury, for instance. Nevertheless, a recent study implies that micro-orgamisms in lake sediments are capable of transforming certain lead compounds into a volatile tetrametbyl lead (Wong et al. 1975). 2.3.3. Lead in food Food is usually the most important contributor to the total lead exposure of the general population. The results obtained from stu dies of the lead content in food have shown broad variations, even as far as the same foodstuffs are concerned (Kehoe 1961 a, Schroeder and Balassa 1961., Lehnert et al. 1969, Horiuchi 1970). For the total intake of food Kehoe (1961 a) arrived at an estimate of about 300 yg/day, and has gained support from calculations made by Harley (1970). In contrast to these studies. Topper and Levin (1972) calculated a mean of abgut 100 yg/day only, for American adult women. A recent report from the U.5.A., moreover, has suggested an intermediate value of 159 to 233 yg (Kolbye et al. 1974). Lehnert and his colleagues (1969) have calculated a mean uptake of 51,8 yg Pb/day for West-fiermany (DBR) , and Vigliani and .Zurlo (1968) arrived at an estimate of 400^.500 yg for Milan. Thompson (1971) has reported a range of 70-750 Pg, and an average of 274 yg in five persons from the United Kingdom; this is not far from the average Of 220 yg derived in Great Britain, by the application of quite a different method (Tolan and.Elton 1972).The DUP040007232 12 8 percent. This figure is supported by more recent studies made by means of stable isotope tracers (Rabinowjtz et al. 1974), al though allowance must be made for the wide range of absorption rates reported by some investigators (Hursh and Suomela 1968, Harrison et al. 1969). The absorption is, furthermore, known to be dependent upon several dietary factors; it is, for example, increased by a high protein content {Milev et al. 1970), a low content of calcium and iron {Shields and Mitchell 1941, Six and Goyer 1970, 1972), and a low content of phosphorus (Goyer and Mahfiffey 1972). .2,4.2, Distribution Lead is distributed by the blood stream where about 95 percent of it i$ bound to the erythrocytes; only a small fraction remains in the plasma. Of the total content of lead in man, about 90 per cent is bound to bone. Teeth have the highest concentrations, and long bones contain more lead than dp flat ones (Schroeder and Tipton 1968, Barry and Mossman 1970). In part, bone lead is firmly bound, with the probable indication of old deposits, and in part more exchangeable, indicating comparatively recent deposits; the latter may contribute to the biologically active pool of the body burden (Task Group on Metal Accumulation 1973). In regard to the soft tissues, the aorta, liver and kidney exhibit the highest con centrations {Schroeder and Tipton 1968, Barry and Mossman 1970). The concept of a higher susceptibility of the fetus to lead is widespread. The transplacental transfer of lead is well docu mented (Kehoe et a], 1933,Horiuchi et al. 1966, Harris and Holley 1972, Haas et al. 197.2), Haas and his coworkers (1972) found no more'than small differences between maternal (16.9 ug/100 ml).and fetal (16.0 ug/100 ml) blood lead levels in a series of 294 sets. The transplacental passage should be taken into account when bio logical standards are being developed for lead. Lead also passes the blood-brain barrier, although it does npt accumulate in the DUP040007233 in to hold a lead content of about 0.01 - 0.02 vg/g under "norm'}" circumstances ( Mirthy and Rhea 1971, Lo t h et al, 1975), It has been reported that the lead content of wine ranges from 0.05 to 0.4 pg/ml (Zurlo and Griffini 1972, Truhaut et al. 1964, Gounelle et al. 1967), This may be of importance in the scrutiny of the differences reported in Pb-B levels from wine-drinking countries (see section 2.5.1.). 2.4. Metabolism of lead In Man 2.4.1. Absorption Absorption occurs through the respiratory and the gastrointestinal routes; in the lungs', absorption is dependent upon the deposition, mucociliary clearance and alveolar clearance (Task Group on Lung / Dynamics 1966). Deposition is dependent upon the particle size ( and respiratory volume. Maximal deposition takes place at a par ticle size of 1 pn at a respiratory rate of 10 per minute, forced respiration diminishes deposition (Nozaki 1966). Through mucocili ary clearance., particles, especially large ones, are transported to the pharynx and swallowed (Task Group on Lung Dynamics 1966). The total absorption through lungs amounts to some 30-40 percent (Mehaoi 1966, Kehoe 19.6lb,Nozaki 1966). In reality, there are pro bably even greater variations of absorption in the general popula tion, provided that the shape of particles present in ambient air is taken properly into account (Lawther et al, 1972 a,b). For the general population,the absorption from the gastrointestinal tract is of major importance,, since food constitutes the chief source of lead exposure. An absorption of about 10 percent has been rather widely accepted. To judge from the review by Karhausen(1972j , a more appropriate value of absorption would be around DUP040007234 2.5.1. Lead in blood According to Pattersson's estimate of man's natural lead concentra tion in the blood of about 0.25 yg/100 ml {19.65), the man-made en vironment has induced an increase ranging from 50 - 100 fold in the Pb-B levels. A great deal of data is available on the blood lead levels of the general population. By far the major proportion of r' these studies have reported that the Pb-B mean values for occupatio nal ly unexposed, rural and urban, populations range from 10 to 25 yg/100 ml (Hofreuter et al, 1961, Butt et al. 1964, Ludwig et al. 1965, Holmqvist 1966, Lehnert et al. 1967, Goldwater and Hoover 1967, Lehnert et al. 1970, Horiuchi 1970, Haeger-Ar.onsen 1971, Tepper and Levin 1972, McLaughlin et al. 1973, McLaughlin and Stopps 1973,Tsuchiya et al. 1974). Studies relating to similar population groups from Northern Italy have consistently disclosed somewhat higher mean values, ranging from 24 to 35 ug/lGO ml (Zurlo et al. 1970, Secchi et al. 1971, Secchiand Alessio 1974). Haeger-Aronsen (1971) reported a mean value of only 8.5 ug/100 ml for 50 women from Southern Sweden. In contrast, relatively high mean values have been reported for both Finnish rural {24 ug/100 ml) and urban {28 ug/100 ml) population groups (Goldwater and Hoover 1967); how ever, this study was marked by methodological deficiencies. As a rule, the Pb-B levels of urban populations, and of people heavily exposed to exhaust gas, have been found higher than those of rural populations (Hofreuter et al. 1961, Ludyrig et al. 1965, Thomas et al. 1967, Lehnert et al. 1970, Horiuchi 197.0, Secchi et al. 1971, Waldron 19.75). An increased lead absorption has also been recorded in people living in the vicinity of lead smelters {Secchi et al. 1971, Nprdman et al. 1973, Martin et al. 1974). No association has been established between Pb-B levels and age (NAS 1972). The influence of cigarette smoking is not fully eval uated; some researchers have reported higher Pb-B levels for smokers than those for non-smokers (Hofreuter et al. 1961, Ludwig DUP040007235 13 brain to any large extent (Schroeder and Tipton 1963, Klein et al. 1970, Barry and Mossman 1970). 2.4.3. Excretion Lead is eliminated extremely slowly from the organism, and pro bably has a biological half-time approximating ten. years (Hernberg 1975). The renal and the gastrointestinal excretion routes are the two most important. Gastrointestinal excretion occurs through secretion or the loss of lead from various glands, the loss by shedding of epithelial cells, and through biliary excretion (Task Group on Metal Accumulation 1973), Renal excretion occurs by glomerular filtration, festal (19.63) has suggested the existence of tubular reabsorption. Minute amounts of lead are also excreted in milk, sweat, hair, nails, and desquamating epithelium* From the standpoint of lead balance within the organism^ these can be ignored, although the importance of lead excretion via the milk fed to the sucklings of mothers subjected to occupational exposure has already been emphasized (section 2.3.3.). 2.5. Concentrations of lead in human tissues Schroeder and his colleagues have made extensive studies of the lead Content of various human tissues (Schroederand Balassa 1961, Tipton et al. 1963, 1965, Tipton and Cook 1963, Tipton and Sbaefer 1964, Schroeder and Tipton 1968), Their results have been corroborated by other investigators (Barry and Mossman T97.0, Horiuchi 1970). As only the lead in the blood and hair .is per tinent within the compass of a population study of the present type, the review of the literature has been confined to these, with emphasis on the lead in blood. DUP040007236 16 2,5,2. Lead In hair As hair is a biopsy material available atraumatically a number of researchers have subjected it to analysis for lead (Schroeder and Nason 1969). Hair is known to contain rather high concentrations of lead. The content seems to reflect total environmental expo-* sure, when judgement is based upon the differences found between lead in the hair of urban and rural populations {Hammer et aj. 1971, 1972, Klevay and Forks 1973). Some studies have shown that lead in the hair is higher in subjects who are occupationally ex posed to lead (Hasegawa et al. 1971, El-Qakhakhny et El-Sadik 1972), and in lead-intoxicated children (Kopito et al. 1967, 1969), 2,6, Parameters reflecting lead absorption Most investigators have accepted the concept that body lead depos its differ with regard to stability. Thus, distinctions are drawn between pools of easily exchangeable lead (blood, internal organs) intermediate exchangeable (muscle, skin), and slow exchangeable lead (bone) (Bolanowska et al. 1963, Pietrpwski 1970, Zielhuis 1972), As no direct method exists for measurements of the total body bur den of living persons we are forced to employ indirect assays for that purpose. There is no doubt that lead ih the blood best de scribes the total exposure for a population group (Zielhuis 1974), but it fails to measure the total body burden. Nevertheless, it correlates well with the rapidly exchanging lead pool which has also been called the biologically available lead (zielhuis 1974).. Lead in urine has often been employed in epidemiologic studies; however, this measurement offers no advantage over Pb-B,as urinary lead is in fact excreted through glomerular filtration, and thus merely reflects the level of lead in the blood. the biologically available lead appears to be even more accurately reflected by the urinary excretion of lead and heme precursors DUP040007237 15 et al. 1965, Tfippfir and Levin 1972), while others have been unable to confirm such an association (Lehnert et al. 1967, Jones et al. 1972, McLaughlin and Stopps 1973). No doubt, most brands of cigarette contain lead to a varying degree (Cogbill and Hubbs 1957, Lehnert et al. 1967). Probably, the amount is connected with the former use of lead arsenate insecticides in tobacco-grow ing districts (Pattersson 1965). Since the 19.50's, the lead arsenates have almost entirely been replaced by organic insecticides. According to Lehnert (1967), the amount of lead in a cigarette , available for inhalation is no more than 0.80 u9/Pb/cigarette, whereas most of the lead remains in the ash (Kehge 1961 b,Lehnart 1967). Consequently the absorption is minimal, when compared with that absorbed from daily food, or from urban air. r' .1 It is known that men have higher Pb-.8 1 five!s than women (Hofreuter et al, 1961, .Ludwig et al. 1965, Thomas et al. 1967, Zurlo et al. 1970, Haeger-Aronsen 1971, Tapper and Levin 1972, Secchi et Alessio 1974). Apparently., the difference is not fully attributa ble to the higher hematocrit values of men (Tepper and Levin 1972). To date, no international agreement exists in regard to biological standards for lead in the blood of the general popula tion, Nevertheless, a proposal, based on available literature, has been formulated by Zi.elhuis (1974), with the total lead expo sure taken into account. According to this biological guide, the highest acceptable individual value within a population group should be 40 ug/100 ml , 98 percent should be below 35 eg/1.00 ml, 90 percent belpw 30 ug/100 ml, and 50 percent below 20 ug/1.00 ml. The Pb-B values of women should be corrected for the haematoerit level. Moreover, the U.$, Environmental Protection Agency has suggested a maximal individual value of 40 ug/100 ml, applicable for adults and children; a maximum of 30 ug/100 ml has been pro posed for expectant mothers and the fetus, as well as for the new born (EPA 1972), \ ' { ; i DUP040007238 IS son program has been undertaken between different laboratories, . and standardization of the Pb-H method is poor. So far, no agree ment has been achieved even in regard to preparation of the hair samples for lead determination (Kopito et al. 1967, Hammer et al. 1972, Clarke and Wilson 1974). The wide range of lead content in hair reported in the literature is undoubtedly largely attributable to the poor standardization of the method. 2.7. Parameters, reflecting, lead effects The lead exposure can also be estimated indirectly by the measure ment of various parameters that reflect effects to the dose ab sorbed. Lead inhibits the activity of certain enzymes involved in the heme synthesis. This effect on the enzymes results in a decline of heme synthesis, inducing a subsequent increase of urinary excre tion of metabolitesi furthermore, the level of the metabolites in blood rises in severe lead exposure.d-ALA dehydratase and ferrochelatase are the best known of the enzymes inhibited by lead. Evidently, higher lead concentrations also inhibit ALA synthetase ' < and coproporphyrlnogen decarboxylase (Goyer and Rhyne 1973, Hernberg 1975). Of the metabolites, coproporphyrin III, and particu larly ALA, have proved to be extremely useful as diagnostic .tests in lead'poisoning (Haeger-Aronsen I960, 1971, Griggs 1964). The accumulation of protoporphyrin IX in erythrocytes ; always occurs at high levels of exposure (Haeger-Aronsen 1971, Sassa et al. 1973). In comparison of the total exposure of various population groups by using a parameter of effect, the validity of the iest should be high at Pb-B levels below 40 ug/ml, i.e., it must be as sensi tive, specific and reliable as possible. A succession of studies has indicated that the AL.AD assay is best adapted for this purpose DUP04Q007239 17 after the administration of a chelating agent (Selander et al. 19.66, Ellis 1966, Teisinger et al. 1969). Chisolm and Well its (1974) have recently demonstrated that the arithmetic increase in Pb-B levels of children and adolescents resulted in an exponentialincrease of lead excreted following CaEDT.A; this accordingly sig nified an exponential rate of increase in chelatable lead in the -^ tissues. A similar relationship between Pb~B and chelatable uri- / nary lead had earlier been reported for adults (Prerovsk and Teisinger 1970). The CaEDTA mobilization test has little value in population studies as it is rather more cumbersome than the Pb-B assay. Use of the lead content in hair for the assessment of excessive lead exposure is well established in literature (Kopito et al. 1967, 1969, Hasegawa et al. 1971, El-Dakbakhny et El-Sadik'1972). It 'has been claimed that Pb-H is correlated with the total body burden (Jaworpwski etal. 1966)This opinion has been questioned by Schroeder and Tipton (1968), who noted that the lead content ,of bones increases wi th increasing age, but found no corresponding increase of Pb-H. The extent to which the Pb-H reflects the biologically available lead is not clear (ZieThuis 1.974),. How ever, Pb-H seems to reflect the total external lead exposure of a population group to a measurable extent, and may thus be of importance for future population studies (Kle.vay and Forks 1973, Hammer et al, 197), 1972, Corridan 1974), The analytical procedures of a Pb-B assay are known to be vulner able to a number of errors with respect to precision, accuracy and reproducibility (Keppler et al. 1970, Weil 1.971, Donovan 1971, Berlin,et a). 197.2, l974a,Browne et al. 1974). It has also been stated that the variability between different laboratories probably arises ffom systematic errors (Berlin et al. 1974a), It is thus easy to question the comparison of the environmental ex posure for various population groups, and the reliability of many epidemiological studies. As for the Pb-B assay, no intercompari- DUPQ40Q0724G however, it has been shown that the rise of these parameters does not begin until the Pb-B exceeds about 40 pg/100 ml (Selander et Cramer 1970, Haeger-Aronsen 1971, Tola et al, 1973). As can be concluded from the Pb-B values reported for groups of the general population (section 2.5.1.), the CP-U and ALA-U is of little value in population studies. In the planning of the .study, it was still considered that the accumulation of protoporphyrin be gan in the proximity of Pb-B levels of 40 - 50 pg/100 ml.. Recent evidence has indicated that, the accumulation is initiated even at Pb-B levels of about 25 pg/100 ml; this applies solely to women; nevertheless, the protoporphyrin is still too cumbersome, and too unreliable at Pb-B levels below 40 pg/100 ml, to be used as a test of environmental exposure (Stuik 1974, Zielhuis 1974, Reels et al. 1975). 19 The fell ability of the method has been assessed in an interlabor.atory comparison study; this disclosed a precision and a reprodueibility of the ALAD assay that surpassed those of the Pb-B test (Berlin e.t al. 1972, 1971 a,b). ALAD is also known to be a highly specific in-vivo-test, although ethyl alcohol exerts an inhibitive effect (Moore et al, 1971). Many cations inhibit the activity of ALAD in vitro; however, no evidence shows that other heavy metals inhibit ALAD in vivo (Hernberg and Nikkanen 1972). Up to quite recently it was unclear whether the inhibition of the ALAD activity in peripheral blood was an in vivo phenomenon or an in vitro arti fact (Goldwater 1972, Zielhuis 1971); however, recent evidence indicates that the decrease is a true in vivo effect (Reels et al. 1974). The sensitivity of the ALAD assay has been demonstrated repeatedly (Bonsignore et al. 1965, DeBruin 1968,'Hernberg and Nik kanen 1970, Hernberg et al. 1970, Haas et al. 1971, Haeger-ArOnsen et al. 1971); furthermore, it displays the closest correlation to Pb-B, as compared to any other biochemical test (Tola et al. 1973V' Sassa et al. 1973). The inhibition probably starts already at about 10 - 20 pg Pb/100 ml blood (Hernberg 1975).; moreover, the sensitivity appears to be high enough to demonstrate 1ow-grade differences of lead absorption (Secchi et al. 1971, 1972, Secchi and Alessio 1974, Coulston et al.- 1973 a,b, Nor.dman et al. 1973). However, as has been pointed out by Stuik (1974) , most data on ALAD have been derived from exposed workers. At the beginning of this Study,, the experience of tihe ALAD assay in population studies was non-existent; it has more recently been suggested that the ALAD test would probably be a suitable tool for surveying the en vironmental exposure of the general population, and for discrimina ting between differences of exposure; (Berlin et al. 1.972, 1974 b). This stucly has provided an opportunity to elucidate the usefulness Of the ALAD assay in the assessment of small alterations in total environmental lead exposure. Other parameters of effect that bear ,a fairly close correlation to the P.b-B are the urinary excretion of ALA and coproporphyrin; DUP0400Q7242 r 22 - 4. GENERAL DESCRIPTION OF THE MATERIAL in the selection of population groups, special care was taken to minimize the inter-individual variation within the groups by the Choice, as far as possible, of locally stable populations of roughly similar socio-economic status, and not exposed to lead in their work. Differences in dietary intake between varying popu lation groups are difficult to discover, but the possibility of . overlooking slight occupational exposure probably constitutes an even greater risk of error. For each subject the possibility of occupational exposure was checked through a questionnaire, fol lowed by an interview. Knowledge of national occupational lead exposure patterns was gained from a parallel study, surveying the degree of exposure in relation to the field of work in Finland (Tola and Hernberg 1975). The questionnaire was specially de signed for the study, for the compilation of information as re gards occupational history (detailed description of former and present work and employment), present and past smoking habits, eating habits, origin of household water, time spent daily out side districts or in traffic, and present medication. The population groups were selected from rural, urban and indus trial districts (Fig. 1). Since sampling at the time involved the drawing of at least 20 ml of blood, it was decided not to include persons under 15 years of age. A summary of the entire series is given in Table 1, The distributions of separate groups by age and sex are indicated in Tables 4,8,22 and 34, - The main rural population group was selected from the Pertunmaa commune, situated about 180 km north of Helsinki. In addition, a diet survey was accomplished, in Pertunmaa with respect to 23 households randomly selected from the original Pertunmaa sample. In order to preclude misjudgement from possible unrecognized special features of the Pertunmaa commune, the rural exposure was DUP040007243 3, OBJECTIVES OF THE PRESENT INVESTIGATION The investigation had the following aims: 1. Determination of the levels of lead in the blood of occupa tional ly-unexposed rural and urban population groups in Fin land. 2. Study of the effects of varying concentrations 0f lead in the ambient air upon blood-lead levels. 3. Study of the effect of industrial lead-emitters on-the blood-lead levels of the. surrounding population. 4. Assessment of the total lead intake of a rural population group. 5. Evaluation of the usefulness of the erythrocyte A-ALAD assay in population studies for discrimination between various ex- . posure levels. DUP040007244 Table 1. Total numbers of persons studied Pertunmaa Pb-B survey diet survey Haapajarvi-Pyhajarvi Helsinki downtown suburban streetsweepers traffic policemen Tikkuriila Total series Males Females All 243 256 35 36 - 93 142 37 37 81 86 n 28 * 121 172 499 71 93 179 118 97 28 293 692 686 1.378 A detailed description of separate groups will be given in con nection with corresponding studies. DU PO40007245 2.3 checked by the selection of another rural group from Pybajarvi .and . Haapajarvi communes, about 400 km north of Helsinki. Fig. 1. Location of the districts surveyed r Helsinki, the largest city of Finland, and the one with the high est traffic density., was selected to represent urban conditions., the urban population groups were all selected from Helsinki, and consisted of a downtown .and a suburban group, with two additional target groups of street-sweepers and policemen. Fifteen kilometers north of Helsinki is the Tikkurila district, a mixed residental and industrial area, and characterized by an exceptional congregation of lead-utilizing industries. Two sec ondary lead smelters, two storage battery plants, and some smaller foundries and a soldering workshop operate within the district. These circumstances prompted the incorporation of the Tikkurila population into the study. The Tikkurila study has been reported separately (Nordman et at. 1973),  : . -J i .;. ; .1 ' J-.it .1; -J - :--r .-\;4" sv; 26 on the filters as dust in sampling cycles of two weeks- The sam pling devices were placed at fixed sampling stations at a height of 2,5 - 3.5 ra. The sampling continued at all sampling sites for one year- Al though air sampling at some sampling sites was effected for more than one year, the results reported here relate only to the period from November 1971 through October 1972; the reliability of the analytical techniques was not regarded as satisfactory before that. Atmospheric lead sampling was carried out in Pertunmaa and Hel sinki. > 5.1.3, Assessment of dietary lead intake Many investigators have estimated the amount of lead ingested dai ly- As pointed out in section 2,3.3- they have obtained very va riable results; moreover, variations have occurred in the sam pling strategy applied. The most accurate method is probably the "double portion" method, with the food consumption being measured by exact weighing (Pekkarinen 1970), This method, which is labo rious and costly, has not proved popular among researchers. With preliminary data on air lead concentrations of Pertunmaa as basis, the assumption was made that almost the entire lead expo sure of the Pertunmaa population originated from dietary sources with the exception of possible occupational exposure that had to be excluded. It consequently seemed worthwhile to study, the exact dietary intake of the Pertunmaa population in relation to the blood lead levels by application of the "double portion" method. The procedure is described in detail in section 6.2.2. DUPQ40007247  l t i ? ! S r r .'. r '": ? '' ` ;/ ' ; . -f ; ."""w . 25 5. METHODS: GENERAL 5,1. Assessment of envi ronmental exposure The results of the jointly-planned dustfali lead survey in Tikkurila, and the studies On air-suspended particulate lead in Pertunmaa arid Helsinki, were made available by the department of taxicology and biochemistry of the Institute of Occupational Health. 5.1,1.. Sampling of dustfali lead Dustfali lead, i,e., -the proportion precipitated from the atmos phere through gravity, aggregation and rainfall, generally de scribes particles with a diameter exceeding 10 era. A dustfali lead survey was carried out in Tikkurila (Laamanen and Ryhanen 1971, Nordman et al. 1973). The sampling was effected by means of collectors consisting of polyethene deposit gauges and bottles mounted on plastic-coated, wooden supporting constructions. The deposit gauge was a modified British Standard .No, 1747 with an orifice diameter of 300 mm,. The modification denotes an increase of the depth to 320 mm, which has proven more efficient in winter-time. The collectors were placed, at a height of 2.5 - 15 m, to avoid the influence of surface dust. 5.1.2, Sampling of air-suspended particulate lead As a rule, , air-suspended lead particles have a diameter of less than 10 jh). The sampling equipment for air-suspended particulate matter comprised a holder with a membrane filter (Millipore AAWP 03700) with a po.re diameter of 0,8 em, and a pump supplying an air flow of about 10 1 per minute (Neuberger V H 15), For meas urement of the terminal air flow, each sampling device was fitted with a gasometer (Nordgas, Stockholm). Air lead was collected DUP040007248 ZB 5.4. Analytical methods 5.4.1. Lead in blood Every Pb-B determination was performed from duplicate samples; thus the reported results of each analysis denotes the average of two parallel measurements. The duplicate samples were analyzed in different runs. The method employed throughout was that of atomic absorption spectrophotometry (P.erkin-Elmer 303), described by Hesse] (1968). The method error of duplicate analyses performed at different periods ranged from 1.1 to 2.0 pig/100 ml. A series of 26 duplicate samples analyzed unbeknown to the laboratory per sonnel showed a method error of 1.7 yg/100 ml; the method error reported by the laboratory for the same period was 1..1 pa/100 ml. The method was continuously checked by the introduction of spiked samples. / During the period from July, 1972 to June 1973, the monthly de terminations of .3 spiked pig blood samples, to which 30 yg of lead (PbClg) per 100 ml of blood had been added (a total of 36 samples), resulted in a mean value of 34,0 yg/100 ml, a standard deviation of 1,7, and a range of 20.5 - 37.7 yg/100 ml. During the same period, a series of 12 human blood samples > to which had been added the same amount (30 yg Pb/iOO ml) of lead, were analyzed monthly without the knowledge of the laboratory staff. These gave a mean of 46.7, a standard deviation of 3.6, and a range of 42.3 - 52.5 yg/100 ml. Unspiked duplicates were currently analyzed. The mean estimated value of the added amount of lead was 31.4 yg/100 ml. New Spiked samples were prepared once a month. The accuracy of the Pb-B method Was further controlled within the compass of an Inter-Scandinavian comparison program organized by Doctors Gustav Weissglas, Ake Swehsspn and Lennart SundelT, Sweden. Spiked and unspiked blood samples have been distributed to the eight Scandinavian laboratories involved. The results of the in ter-laboratory comparison are presented in connection with the studies concerned (Tables 6,24,25). DUP040007249 27 5.2, Choice of parameters of absorption and effect The lead concentration in the blood was employed as a parameter indicating lead absorption, and the erythrocyte ALAD activity as a parameter of effect . The advantages and drawbacks of these, and other pertinent biological variables indicative ,of lead ab sorption or effect, have already been discussed (section 2-6. and 2.7.}. ,5.,3, .Collection of biological samples All of the blood and dietary samples collected for the determina tion of lead content were stored in lead-free polyethene flasks or bottles which had been carefully washed with 10 percent nitric acid, and repeatedly rinsed with demineralized, distilled water. Blood samples were drawn from a cubital vein into lead-free flasks. Only stainless steel syringes with polypropylene hubs were used. The skin was cleaned with a 0.2 percent benzethone chloride solu tion containing 2.3 percent butanol and, as solvent, 6.8.9 percent isopropanol. An amount of 20 ml of blood was drawn from each per son for Pb-'B analysis; duplicate samples were drawn from every fifth, for storage and future analysis. The Pb-'B flasks were stored deep-frozen until analysis. Samples for ALAD determination were drawn into heparinized test tubes of TO ml capacity. Other wise, the test tube? were prepared analogously with the Pb-B flasks.. For determination of the hematocrit value and the hemo globin concentration, 2,5 ml of blood was drawn into ,a test tube containing 4 mg of EDTA. - ' DUP040007250 30 5,4-5. Dustfal1 lead The water-soluble fractions of the total dustfal1 were analyzed for lead by the atomic absorption spectrophotometry method. The ashed samples Were analyzed by emission spectrography (Jarrel Ash Type 7101). The results obtained as micrograros per sample were 2 transformed into grams per 100 m per month. 5.4.6. Lead in air The air-suspended particulate matter obtained on the membrane filters was analyzed for lead directly by X-ray fluorescence spectrometry (Philips PW 1410). A lithium-fluoride crystal (LiF 200), and a wolfram anode tube were employed. The X-ray gener ator was set at 60 kV and 30mA. Lead was determined from the alpha-line, .2-theta angle = 33.91. Measurement was effected three times, each one extending over a 20-second period. Background was determined at a 2-theta angle of 34.50. (Kuronen unpublished. Philips 1973, Grennfelt et al. 1971). The method was checked by parallel determination with atomic absorption spectrophotometry. The comparison is accounted for in Table 2. 5.4.7, Lead in food and beverages All -samples of food and bevs-ages, including the water samples, were analyzed by application of the same method. The samples were evaporated, and then completely ashed at a temperature of 4Q0-.5QOC, After the addition of hydrochloric acid (West and Carlton 1952), the lead portion of the fully ashed samples was extracted as the iodine complex with methyl isopropyl ketone (Talvitie and Garcia 1965). The final lead determination was effected wi th an atomi c absorpti on spectrophotometer., A com parative check on the method was carried out by K.H. Schaller, M.D. at the University pf Erlangen-NUrnberg, West Germany; the results of this check are listed in Table .3. DUP040007251 > 1 : ...:i : ] - _ . / ' -V; ' ? i ;:v- . v - -- -- r- :-V'" -.> " < ' w. *" - . V - n A series of duplicate samples were also analyzed twice a year in the laboratory of the American Smelting and Refining Company (ASARCO), Utah, 11.S.A. These are 'accounted for in Tables 7 and 26. The samples of both the accuracy control programs were first analyzed at the Institute of Occupational Health, and the results were passed to the reference laboratories concerned before reports of their results had been received. ,, 5.4.2. Erythrocyte A-ALAjQ activity Erythrocyte A-ALAD activity was measured by a modified version of the method of Bonsignore and his colleagues (Bonsignore et al. 1965, Nikkanen et al. 1972). Briefly, the modification involves the use of the more stable sodium phosphate buffer and a pH of 6.8, instead of the carbonate buffer and a pH of 7.0. The activ ity is expressed as micromols porphobilinogen (PBG) formed during one hour of incubation at 37C per iiter of packed red blood cells (RBC), The RBC volume was estimated from the hematocrit value measured previously. The method error from duplicate measurements .during different period ranged from 18.4 to 36.0 pmol PBG per liter RBC. The values of the method error will .be reported separately in connection with the surveys concerned.. All of the ALAD assays were made within 5 hours of sampling. 5.4.3. Hematocrit value The hematocrit value was measured with an Adams AutOcrit centri fuge (CT 2900). Duplicate blood samples were spun for 4 .minutes at 15,000 g. 5,4.4, Hemoglobin concentration Blood hemoglobin was determined by the standard method, after con version to cyanme.themoglobin. t - ' ' - ` .'.V, " .. DUP040007252 32 Table 3. Accuracy check of the lead-in-food assay, provided by the laboratory of the University of Erlangen-Nurnberg Ashing performed at the Institute of Occupational Health. Values expressed as ug/100 g. Sample No, ' l''' 2 .3 4 5 67 8 9 10 11 12 13 14 15 ErlangenNurnberg value 26.5 14.7 14.2 13.0 10.6 8,5 19.8 16.2 18.2 13,7 11,8 10.5 14,1 10.3 8.7 Present value 23.8 26,3 22,1 11.6 17.5 .14.8 21,4 24.3 11.5 11.5 16 J 12,5 . 21.4 9,7 14.4 DUP040007253 31 Table 2, Comparison between X-ray fluorescence spectro metry and atomic absorption spectrophotometry. Values expressed as micrograms per sample. i May - Juiy 1973 August 1973 if i Sample No, X-ray AAS Sample No X-ray A/S 's 1 261' 143 18 520 666 2 26 23 19 165 205 3 23 20 62 61 4 460 449 21 32 37 5 1170. 819 22 7 6 6 1246 774 23 ' 22 19 7 1035 552 ' 24 37 33 8 106 93 25 24 20 9 1255 1172 26 202 198 :! 10 581 633 11 50 55 12 103 132 13 86 87 14 4.7 52 15 10 22 16 25 34 17 55 73 ! DUP040007254 .34 . 6. ENVIRONMENTAL LEAD EXPOSURE OF A RURAL POPULATION A study on dietary intake, exposure from ambient air, and blood lead levels. fi.l. Introduction This investigation was conducted in the Pertunmaa commune, about 180 kilometers north of Helsinki (see Fig, 1). The total area of the commune is 474 square kilometers. In 1971 the number of in habitants was 3,510 (1,752 men and 1,758 women)x^, i.e. 7,4 iohabitants per square kilometer. The vast majority of the popula tion earn their livelihoods as small farmers or farm laborers. The industrial activity of the commune is restricted to a few small work shops; no lead plant operates within the district. In 1971, 552 automobiles, 497 of them gasoline driven, were re gistered in Pertunmaaxx). The population of Pertunmaa appeared to be suitable for the purpose of studying the daily lead intake and bipod lead levels of the general population living in condi tions of a minimum of lead pollution of the ambient air. 6-2. Material and Methods 6,2.V. Blood lead survey In the fall of 1.970, a systematic family sampling was effected. This sampTing was undertaken in order to facilitate transportation to the place of examination. Of the .653 persons initially in- Central Statistical Office of Finland xx) From: Automobiles and Highways in Finland 1971, Finnish Road Association. DUP040007255 33 5.5. Statistical treatment The normality of the distributions of separate series was tested by use Of the Kolmogorov-Smirnov statistic for cumulative fre quencies. In all but one series, a slight skewness was revealed. Graphically assessed, however, only the Tikkurila series disclosed a skewness that demanded a normalizing logarithmic transformation. In view of the skewness of the Tikkurila series, the Kolmogor.ov-Smlrnov statistic was chosen for the testing of significance between the Tikkurila series and others. As for all other groups, the Welsh's modification of the Student t-test was applied in the testing of significance of differences between the group values. This procedure takes into account the difference in the variances of the separate series by modifying the degree of freedom in the calculated t-test statistic . The robustness of the t-test was considered sufficient to compensate for the slight skewness of the distributions in all groups but for the Tikkurila group. This consideration w&s supported by the results obtained by re-testing the differences using the non-parametric Mann-Whitriey U-test- the procedure did not alter the degree of significance arrived at by the parametric t-test. Two-tailed p-values were computed through out. The Pearson coefficient of correlation was applied in the measure ment of the degree of relationship between characteristics of population groups or between parameters of interest. The analysis pf variance was used in testing the effect of age on Pb-B levels,. The standard deviation of measurement error was calculated from the formula: where d = difference between duplicate measurements n = number of pairs of duplicate measurements DUP040007256 : : s ' ' -1 v -j 36 Table 5. Cigarette-smoking habits of the Pertunmaa population Cigarettes dai ly Males Females All >20 . 10 io 10-20 <10 42 43 1 18 43 61 cigar or pipe 6 - non smokers 142 237 6 .379 The collection of blood samples was carried out in the way de scribed earlier (section 5.3.). On the same occasion the question naires were checked and completed. Blood samples were stored deep-* -frozen until analysis for lead, Hb and PCV was measured on the day of sampling. Both winter and summer samples were analyzed in the fall of 1971. The winter blood samples were mixed with the sunmer samples, and each run contained similar proportions of both. The inter-mixing was done with a view to the avoidance of systematic errors when comparing the seasonally differing groups. The method error of .399 duplicate Pb-B measurements was 1,8 pg/ 100 ml. The results of the accuracy check of the Pb-B method carried out during the corresponding period at seven other Scandi navian laboratories, and at the laboratory of the American Smelting and Refining Company (ASARCO), are illustrated in Table 6 and Table 7, respectively. DUP040Q07257 4 '$ Vi, . i : A! V 1 35 vited by letter to parti.cipate,, 515 responded. Nine persons in all were excluded because of slight possible occupational lead exposure* and an additional 7 for technicat reasons such as the clotting of blood samples. Of the 499 persons who constituted the final series, 243 were males, and 256 females. The age dis tribution of the entire series is indicated in Table 4. On the whole, the different age groups are of similar size, and the sexes are equally distributed. The oldest group, i.e,, those over 65 years of age is, however, the smallest of both :males and females,. Table 4. Distribution of the Perfcunmaa population by age and sex Age 15-24 .25-34 35-44 45-54 55-64 65 or more Males Si 35 50 34 43 30 Females 49 32 40 56 56 23 All 100 67 90 9D 9.9 S3 Total 243 '256 499 Cigarette-smoking habits are shown in Table 5. Smoking did not appear to be as common a habit as anticipated; thus, only 19 females were cigarette-smokers, none of them was a heavy smoker., and 1$ smoked less than 10 cigarettes a day. Only 10 of the males reported that they smoked more than 20 cigarettes a day. To disclose any possible seasonal fluctuations in Pb-B levels, approximately half (247 persons) of the group were examined be tween December 1970 and January 197], and the other half (253 persons) during the period from June to August 1971. The age distribution and the cigarette-smoking habits of the winter and summer groups were identical with those of the entire series. DUP040007258 38 6.2.2. Diet survey Several different methods are available for the assessment of food consumption, such as food accounts, interviews, questionnaire and weighing procedures, all of which have certain advantages and draw backs. The method employed here was that of weighing, also known in the literature as the recipe method {Wilson et al. 1964), the exact or precise weighing (Pekkarinen et al, 1967) and the weighed individual-inventory method {Durnin et al- 1957), It is the most accurate method for the assessment of food consumption of individ uals or families {Pekkarinen 1970), 4 trbifted investigator super vised the weighing, which was done by herself and two students. In advance, the participants received detailed information re garding the study personally from the same investigator, who em phasized the importance of not altering the usual composition of meals. For the reasons of costs and feasibility, the recording period had to be restricted to three {consecutive) days; earlier reports had indicated reason to expect considerable day-to-day variation of dietary lead intake (Thompson 19.7T), sp that a longer period would have been preferable. The subjects of the diet survey were randomly sampled from the orginal Pertunmaa family sample. The use .of trained personnel for the weighing eliminated possible misunderstandings, and thus made random sampling possible. Thirty households were asked to partic ipate; of these, 23 representing a total of 71 individuals ressponded. Of the 71 respondents {35 men and 36 women), 46 had also participated in the former blood lead survey. The age and sex distribution is indicated in Table 8. Cigarette smoking was rather uncommon: only 13 were smokers, 3 of whom were women all smoking less than 10 cigarettes a day; of the 10 male smokers only one was a heavy smoker, viz. more than 20 cigarettes a day, and ,5 intermediate smokers, i.e., 10 to 20 cigarettes a day (Table 9). DUP040Q07259 37 Table 6,. Inter-Scandinavian accuracy check of Pb-B determi nati on in fall 19,71, Values expressed as ug/10.0 ml. Sample Mo. 1 2 3 4 .5 Lead added 30 -' 14Q 80 Mean of 8 laboratories 41. n 11 136 93 Range of 8 laboratories 31-48 4-17 4-18 118-155 79-101 Present value 48 14 14 155 101 Tabl e 7. . American accuracy check of Pb-B determination in 1971. Samples 1 and 6, 2 and 7, 4 and .8 are duplicates. Values expressed as pg/100 ml. Sample No. 11 2 3 4 5 6 7 8 ASARC0x) value , 21 29 22 17 4 8 23 16 Present value 19 22 21 16 16 19 22 16 x) American Smelting and Refining Company., Utah, U.S.A, ! ,i DUP040007280 40 All of the household members were kept under individual survey. Thus., all items of food to which a single respondent helped him self were weighed separately before eating, the plate waste and the discarded food were also weighed, and the total amount con sumed calculated by this means. All snacks between meals were weighed. The total number of meals eaten outside homes was only 16, snacks included. Their share of the total lead intake could not be measured,, only estimated, from each meal, one fifth of all food substances was collected for analysis, but only one sample of water and other beverages was taken from each household. The solid food substances in gested by every respondent were daily pooled, thoroughly homoge nized, transferred ]t|> lead-free,bottles, and finally deep-frozen.. When homogenizing, "the precise amount of added demineralized water was weighed. The food consumption Survey was effected during the period from May 25tb to June 23rd, 1972. Blood was sampled for lead analysis from each participant in connection with the survey. The hemo globin concentration and the hematocrit value were determined on the day of sampling; the P.b-B samples were intermixed with the Helsinki .and Haapajarvi-Pyhajarvi samples with a view to compa rability between urban and rural Pb-B levels. :p.2.3. Lead in ambient air Air-suspended particulate lead i.n Pertunmaa was monitored from October 1971 to November 1972. The samples were collected at one fixed sampling site. , filters were placed at .a height of about 2 meters. The equipment has been described in section 5.1..2. The samples of May 1972 had to he discarded following technical failure in connection with the collection. DUP040007261 39 Table 8,. Distribution of diet survey respondents by age and sex Age group Males 15-24 25-34 35-44 45-54 55-64 65 or more 8 45 .. 7. 7 4 All 35 Females 6. 3 4 9 9 6 36 All 14 7 9 16 . 16 9 71 table 9. Cigarette-smoking habits of diet survey respondents Cigarettes dai 1 y Mai e.s Females >20 1 * 10-20 <10 non-smokers 5 4 25 3 33 All 15 7 58 DUP040007262 6.3.2. Daily lead intake The total daily lead intake through food and beverages of the 7l respondents of the dietary survey is illustrated in Table 11. A mean intake of 204 yg Pb/day was found. The standard deviation of the mean value for the three days was 67, and the range 89-360 yg Pb/day. The mean intake of men was higher than that of women, 2,31 yg and 178 yg, respectively. The difference is statistically significant Table 11. Daily dietary lead intake of 71 persons on three con secutive days of sampling. Values expressed as ..micro grams of lead, Day of sampling I IT HI Mean of three days Males (N--35) x. SD range 226 6.6 89 - 335 230 78 137 - 496 237 83 96 - 430 231 59 119 - 360 Females (N=36) X SD range 173 .64 73 - 352 18.2 77 81 - 387 T79 82 46 - 404 178 64 89 - 305 All (N=71) X SD range 199 70 73 - 352 206 80 81 - 496 .2.08 87 46 - 430 204 . 67 89 - 360 (t = 3.64, p<0.001). The contribution from beverages (Table 12) is small as compared to the lead ingestion through solid food (Table 53), constituting about 15 percent of the total daily amount ingested. The mean intake through beverages of men was 46 yg Pb/day and that of women significantly lower (t ?= 5.61, pO.DOl), i.e., 25 yg...Pb/day. The intra-individual day-to-day variation was great* 6.3. Results 6.3.1.Lead in ambient air As had been expected, the lead content of the ambient air in Per tunmaa was low throughout (Table 10)> The highest monthly mean \- 3 value was recorded in February 1.972, and was .0,056 ug/m of air. The early mean value for the whole period from October 197] to September 1972 was only 0-025 ug/m . Thus airborne lead could be considered negligible as a contributor to the total lead exposure of the population of Pertunmaa; even a daily inspiratory volume of 20 m3 , and an assumed TOO percent resorption following a maximal retention of 50 percent would result in a daily resorbed amount of lead of no more than 0.25 ug. Table 10. Monthly and yearly mean concentrations of air-sus pended particulate lead in Pertunmaa, Values expressed as u/m . 1971 1972 November December January February March Apri 1 May June July August September October Monthly mean 0.02 0.02 0.06 0.06 0.03 0.01 , *)0.02 0.01 0.02 0.02 - Yearly mean V\ ' " - . ' 1 ............. ' Stroke denotes omission of sample 0.02:5 DUP040007264 44 Table 14. Lead content of drinking water and milk from twenty-three households. Values expressed as yg/kg. Water Milk X 23 32 SO J. 6 ' min. 15 22 max. 41 42 Table 15. Lead content of some beverages. Lead determined from pooled samples of twenty-three households. Values expressed as yg/kg. yg Pb/kg Coffee : Tea Beer; brand A B c Home-brewed beer Home-brewed mead Lemonade 9 8 8 10 11 24 23 15 No correlation could .be established between the daily lead intake and Pb-B levels of the 66 persons for whom blood samples were aval 1 able; The coefficients of correlations were r = 0,p8 for men, r = 0,05 for women and, for the entire series, r = 0,05. The mean Pb-B of 33 males participating in the diet survey was 12,3 yg/100 ml; the corresponding value, for the 33 females was 7,9 pg/100 ml (Table 28). DUP040007265 Table 12. Daily mean lead intake through beverages. Values expressed as micrograms of lead. X SD min:. max. ......... : Mai es (N=35) 46 20 19 1]6 Femal es ,{N=36) 2$ 9 4 47 All (N=71) 35 19 4 116 Table 13. Daily mean lead intake through solid food. Values expressed as micrograms per day. Males Females All - (N=35) (N-36) . (N=71) SD min. max. 185 153 169 60 61 62 79 71 71 310 261 310 Each family under survey had a private well. Only 4 families bought their milk from stores, whereas 19 families had their own cows. The lead content of milk, water, three of the most fre quently used brands of beer, tea, coffee and home-brewed beer and mead is accounted for in Tables 14-15. The lead content of coffee and tea was surprisingly low as compared to the drinking water. DUP040007266 46 15 and 64 years of age were considered (F = 2.07, p >0.1). Table 17 , Pb-B levels of Pertunmaa female population. Values expressed as pg/100 ml. Females Age NX S.D range 15-24 4.9 10,2 3,3 5 - 18 25 - .34 32 9,5 4.1 5 - 28 .35. - 44 40 9.1 2,8 4 - 17 45 - 54 56 10-0 3,1 5 - 1.8 55 - 64 .56 9,6 4.2 3 - 30 .65 or more 23 8,3 2.9- 4 - 1.5 All 256 9,6 3.5 3-30 The seasonal influence on Pb-B levels is presented in Table 18. The females revealed' a distinct difference between summer and winter Pb-B levels, the summer level being higher than the winter level. The Pb-B level of the males was only slightly higher in summer as compared to the winter level. Table 18. Seasonal influence on Pb-B levels of Pertunmaa populati.on. Values expressed as yg/100 ml Males Winter Summer Females Winter Summer X 11.8 12.4 SD 4.5 4.4 N 1)3 130 t -1,05 P >0.1 8.9 10.4 3.0 3.8 133 123 -3,49 <0.001 DUP040007267 45 6.3.3. Blood lead survey The Pertunmaa males displayed a mean P,b-:B of 12.1 yg/100 ml (S.D, 4.5, range 2-35 yg/100 ml). The lowest mean Pb-B value was found in the oldest group (over 65 years), and the highest in the young est group (15 - 24 years ). The difference between these two groups was statistically significant (t = 2.55, p<0.05) (Table 16). Table 16. Pb-B levels of Pertunmaa male population. Values expressed as yg/100 ml, Males Age Nt ,SD ` range 15 - 24 25 - 34 35 - 44 45 - 54 55 - 64 65 or more si 35 so' . 34 43 30 13.5 12.3 12.3 10,8 12.3 10.5 4.4. 4.5 ' 4.2 3.0 4.7 5.5 6-25 5 - 21 5 - 24 2 * 17 5-25 4 - .35 All ,243 12.1 4,5 2 - 35 As compared to the males, the famales disclosed a lower mean Pb-B value of 9.6 yg/100 ml (S.D. 3.5, range ,3-30 yg/100 ml),The lowest mean Pb-B of the females was similarly found in the oldest group, and the highest in the youngest group (Table 17), However, no association between age and Pb-B was detectable for the females (F = 1.25 p >0.T). On the other hand, the males displayed a decreasing mean Pb-B value with increasing age.. This correlation was statistically significant (F 2.47, p<0.05). The association was highly dependent on the oldest age group; consequently, the correlation disappeared when only men between DUP040007268 ! " " * i-- ! ". ..>?.-. . - ' \ . - ; :-V- ' 48 validity of conclusions based upon the Pb-B levels obtained de pends to a large extent on the validity of the Pb-B measurement. As was pointed out in an earlier content, the Pb-B assay is sus ceptible to many errors (Keppler et al. 1970, Berlin et al. 1972, 1974a). In this study, the precision of the Pb-B assay appeared to be on a high level, with a method error of 1.8 ug/100 ml. Appraised from the Inter-Scandinavian and the ASAROQ comparison program, the accuracy was also satisfactory. The low values found in Pertunmaa are too high rather than too low as compared to the reference laboratories; the validity of the Pb-B assay is further examined in the general discussion. One important consideration is that the P.b-B level of the 46 per sons who delivered blood samples, both for the bipod lead survey, and for the diet survey, exhibited a slight but statistically sig nificant decrease over the period of one year {Table 20). There is little reason to believe that the true Pb-B level of this group decreased in about one year; it is more likely that the differ ence only describes a systematical difference of the Pb-B tech niques, In other words, despite the strict control of the Pb-B method, a small systematic error could not be avoided between the measurements, of the two periods of analyzing. The preparation of standards, still .carried out every third month in 1971 but effect ed every month at the time of the diet study, probably explains the difference,. The measure of monthly preparation ,of new stand ards was taken after the discovery that the Pb-B values of the spiked pig blood samples (used as standards) decreased with in creasing storage bimp. Such considerations should be borne in mind when evaluating'data in the literature reporting the presence or absence of time trends with respect to Pb-B levels in popula tion studies (Horiucbi 1970, Tepper and Levin 197.2, McLaughlin et al. 1973), HowevMr, it should be emphasized that the system atic error did not confuse the results of the seasonal compari son of Pb-B levels because of the inter-mixing of samples. } I V { i -i > DUP04G007269 - -r' v; 3 47 The difference between mate and female mean Pb-B values was dis tinct (t = 6.91, p<Q..QGl), The Pertunmaa material contained 108 pairs of husbands and wives,. A comparison between Pb-B levels of husbands and wives did not greatly alter the inter-sex Pb-B differ ence (t = 3.54, p<0.001), When the lead content is referred to the volume of packed blood cells instead of the blood volume, the in ter-sex difference is diminished, but still persists {Table 19). Table 19. Inter-sex differences of lead referred to whole blood volume add to packed blood cell volume. Values expres sed as pg/100 ml of blood and eg/100 ml of packed blood cells.:; Pb-B Pb content referred to PCV Pb-B . Pb content referred to PCV Males Females Males Females Husbands Wives Husbands Wi ves % 12,1 9,6 26,6 23.2 11.4 9.5 25,3 .22,9 SD 4.5 3.5 9.8 8,5 . 4.0 4.0 9.0 =9.9 243 256 : 239 255 108 108 107 107 t 6,91 ; 4.11 3.54 1,86 P <0.001 <0.001 <0.001 - 0.06 For the males, no significant difference was .obtained between mean Pb-B values of smokers and nonsmokers. The smokers had a mean value of 12.8, and the nonsmokers 12.0 pg/100 ml (t = 1.36, p>0.1),. As the female cigarette smokers made up less than 10 percent of the entire group, it was impossible to assess the influence of cigarette smoking pn Pb-B levels within this particular group. 6.4. Discussion 6.4.1. Blood lead levels On the whole, the mean Pb-B values were lower than those generally reported in the literature, .especially as regards Hie women. The r DUP040007270 50 Table 21. Pb-B levels of Pertunmaa males in relation to nature of activity Pensioners Farmers Students* Lumbermen Others N X so 20 10.3 3.5 125 11,8 4.7 22 12,7 ` 3.3 25 13.4 5,8 51 12.7 3.8 * including 14 students spending $ days a week in Heinola, Joensuu or Lahti ** Including farmers doing lumbering work in wintertime 6.4.2, Dietary lead intake The daily amount of lead consumed was lower than that quoted in some reports (section 2,3.3.); however, Tolan and Elton (1972) reported very similar values from Great Britain and Kolbye and his co-workers (1974) have also calculated a mean intake of the same order of magnitude. By comparison, the value of 100 ug Pb/day for American adult women seems very low (Tepper and Levin 1972). Nevertheless, it must be emphasized that roost estimates have been reached by the use of different designs of study, and varying analytical procedures. The lack of standardization with respect to methodology is a serious drawback which obscures any compari son of results. In this study no relationship Was detectable between the Pb-B and the dietary lead intake. This was presumably due to the great day-to-day variation; a longer recording period would probably have disclosed the existence of such a .relationship. DUP040007271 49 Table 20- Differences between individual Pb-B levels obtained in Pertunmaa in 1971 and 1972 Males Females All N 23 23 46 Ax -1,04 - -2.57 -1,86 ASD 2.12 2.66 2,58 t -2.36 -4,62 -4.73 P <0.05 <0,001 <0.001 The higher Pb-B level for men than that for women corroborates the findings of roost researchers (Hofreuter et-al. 1951, Ludwig et al. 1965, Tepper and Levin 1972), with few exceptions (Goldwater and Hoover 1967), The higher Pb-B level of males existed even after correction for hematocrit level, but diminished. The distinct difference between the dietary lead intake of men and that of women (section 6.4.2.) may account for part of the differ ence. Nevertheless, it is probable that the rather marked differ ence between the means of males and females of this series arose partly from inter-sex differences with reference to activities. The men of this study were over 75 percent manual laborers, most of whom were farmers. It can be seen from Table 21 that Pb-B levels vary, depending on the kind of activity. The least active group, i.e., that of pensioners., has the lowest mean Pb-B value, and the lumbermen exposed tp .chain-saw exhaust display the highest mean. In contrast, the women were almost exclusively housewives or students. There is thus reason to believe that the association between age and Pb-B levels, found in the male group only, was an effect of variations with respect to environmental exposure rather than to age.; furthermore., that the absence of a clear seasonal variation for the males was due to the effect of slight additional exposure, since small farmers are frequently engaged in lumbering during fall and winter. These aspects may account for at least part of the reported decrease in the tissue levels of old people (Schroeder and Tipton 1968). DUP040007272 5.2. par.atively low., and clearly below the 300 pg Pb/day which has been considered as the representative mean intake:. Since the atmospheric lead exposure is very low in Pertunmaa, the lead levels, at least for women reflect the lead absorption from die tary sources. These Pb-B levels are among the lowest ever re ported. The results indicate that the inter-mixture of samples is neces sary, even when they are all analyzed in the same laboratory. Otherwise no guarantee exists that systematic errors are avoided. DUP040007273 < v.- ... 51 Since the lead exposure derived from ambient air was negligible, particularly for the women, it may be postulated that the Pb-B levels found represent the lowest levels to be expected in groups of the general population in industrialized countries. With the acceptance ,of an overall gastrointestinal absorption of 8 percent (Waldron and St'dfen 1974), the daily average absorption for the population surveyed would be 16 yg Pb/day, with a minimum of 6 yg, and a maximum of 29 yg.. The corresponding daily mean for men would be 18 yg, and that for women 14 yg daily. Genera lization with regard to dietary habits of the Finnish population is risky, since recent evidence has indicated the existence of some dietary variations between Finnish urban and rural popula tions (Koskinen 1974). Although co-operative chains distribute most of the food consumed in Finland, the possibility of varia tions within the country with respect to .mean lead intake cannot be excluded, 6.4.3. Lead in ambient air The low concentration of lead found in the ambient air of Pertunmaa is in accord with the recent study on heavy metal deposition in Scandinavia (Ruhling and Tyler 1973), which has reported a modest lead content of mosses from Finland, as compared to south ern parts of Sweden and Norway. The concentrations in Pertunmaa are of a similar order of magnitude as values reported earlier from remote rural, non-industrialized areas, (CEC 1.972) or even somewhat lower. 6.5. Conclusions From an international point of view the Pb-B levels of the Per tunmaa population are low. The dietary lead intake is also com- DUP040007274 l- ; 1- tm ;v :.i .5- - =. ... 54 mendable decisions made with a view to the reduction of lead pollution are largely based upon results obtained in American population studies. However, the U.S.A. differs from Europe, ..and from Scandinavia in particular, in many relevant respects, such as the previous use of lead pigments, traffic density, and the degree of industrialization. By reason of the lack of data from Scandinavia, it was decided to study/the P.b-B levels in Helsinki and the relationship between them!, and to compare urban and rural conditions. In 1972, Helsinki had about 510,000 residents, i.e., 2,900 in habitants per square kilometer*^. At the tine, the total number of automobiles registered in Helsinki, .according to the holder's domicile, was 110,000, of which 100,000 were gasoilne-driyen*xx). However, the inhabitants of adjacent communes bordering on Helsin ki are to a large extent commuters working in the city. When these communes are taken into account, the. totals rise to 730,000 people, and 140,000 gasoline-driven automibiles, respec tively. Finland has no statute pertaining to the maximum con tent of lead in gasoline:. According to the national refinery, the addition of lead to gasoline has never .exceeded 0.7 g/1 (personal communication, Neste Oy), x) Central Statistical Office of Finland xx) From: Automobiles and Highways in Finland 197.3, Finnish Road Association DUP040007275 -L- -! - : Vi.;'. C *'L ' 53 7. BLOOD LEAD LEVELS AND ERYTHROCYTE A-ALA DEHYDRATASE ACTIVITY OF SELECTED POPULATION GROUPS IN HELSINKI It is now known that traffic increases the lead content of air {Ludwig et al. 1965, Thomas et al. 1967, Tepper and Levin 1972, Baines et al. 1972, CEO 1972, Gothe et al, 1973). Furthermore, the isotopic composition of lead aerosols in air indicates that the decomposition products of lead alkyl are the main source of the lead in urban air {Chow and Earl 1970), In close accord with this, several studies have disclosed that exposure to exhaust gases increases the bipod lead levels (Hpfreuter et al. 1961, Ludwig et aT. 1965, Thomas et al. 1967, Lehnert et al. 1970., Horiuchi 1970, Daines et al. 1972, Waldron 1975), However, it is still necessary to determine the concentrations of lead in the air which will increase the lead absorption to a measurable extent. The U.S. Environmental Protection Agency, following a review of studies on the subject, has declared that lead levels of around 2 ug/m3 of air induce a measurable increase in blood lead levels among adults (EPA 1972). The existence of an association between Pb-B levels and lead concentrations has been supported by a controlled 18-week chamber exposure study at about 3 gg/m3 , which resulted in a rise of blood lead levels (Coulston et al, 1973 b). In contrast, Tepper and Levin {1972) have not found any relation ship between annual air lead concentrations, ranging from 0.14 to 4,55 gg/ro and blood lead levels. Although it is impossible to draw any definite conclusions yet, measures to lower the content of lead in gasoline have been adopted by a number of Governments (Campbell 1973). However, little is known about the Pb-B levels of Scandinavian populations, and even, less about the probable hazards that arise from the pro bable alternatives replacing lead (Berlin M. et al. 1974), The cbm- DUP040007276 56- 7.2.2. Selection of population groups The population groups under survey were -selected from regions surrounding the air .sampling sites. Two main population groups were formed in Helsinki: a downtown group .derived from head post office employees, who both, worked and resided within the downtown area, and a suburban group comprising employees, store clerks and clerical staff working and residing within the suburban dis tricts concerned. in addition, studies ware made of two target groups with special exposure patterns; these comprised 97 streetsweepers, all of whom had their working place in downtown districts, and 28 of a total of 61 traffic-directing policemen operating at the time in Helsin . ;-i ki, 1 To obtain control groups for the Helsinki series, two rural popu lation groups were selected.: one was made up of the 33 men and 33 women participating in the Pertunmaa dietary survey (5 Pb-8 samples were lost). The other one was formed of 93 female post employees from Haapajarvi and Pyhajarvi communes (Fig. I), The rural com munes of Haapajarvi and Pyhajarvi are both situated about 400 kilometers north of Helsinki, with about 8,000 inhabitants and less than 1,500 automobiles each. The numbers of inhabitants per square kilometer is 5.9 for Pyhajarvi, and 9.9 for Haapajarvi xl The corresponding data for Pertunmaa are given in section 6,1. ! Distributions by age and sex of the different groups are in dicated in Table .22,and the smoking habits in Table 23. x) Central Statistical Office of Finland DUP040007277 Ur': i 55 7.2. Material and methods 7,2.1. Aerometric sampling The sampling of air-suspended particulate lead was effected at four fixed sampling sites. The downtown sampling site (1) was situated about 300 meters from the head post office, close tq the city railway station (Fig. 2.). Sampling site 2 was situated in a mixed commercial, industrial and residential area, sampling site 3 in the suburb of Pphjpis-Haaga, and sampling 4 in the sub urb of Qtaniemi . The equipment, and the procedures for sampling and analysis are described in section 5, No, .3 suburban of Pohjois-Haaga, No.. 4 = suburban of Otaniemi. A - Helsinki main incinerator, B = Tikkurila lead emitters at a distance of about 10 kin from sampling site No. 3, C = Haags .3 Power station, 0 - lead pigment plant. DUP040007278 Table 23. Cigarette-smoking habits of different urban and rural population groups. Downtown Males Females ATI Suburban Males Females All Strpetsweepers Males Females All Policemen Males Haapaj arvi Pyha'jHryi Females Pertunmaa diet survey Males Females. All Cigarettes dai ly >20 10-20 <10 17 42 13 1 97 18 51 20 4 96 1 13 12 22 18 12 20 .8 1- 12 21 8 2 53 3 18 1 54 -- - 3 1 57 Pipe or cigars NonSmokers 6 69 - 22 6 91 2 16 1 56 3 72 .2 44 - 10 2 54 T8 72 25 - 33 58 DUP040007279 '93 | Table 22. D is trib u tio n o f d iffe re n t urban and ru ra l population groups by age and sex. 57 HaapajarViPyhajarvi Females 26 23 CJ CO rc-rm* CM >* >03 (/) XU 3 S- rr" ec ^v> frco 3 (13 4j :h S- <u CJ *0.-0 VI OJ * ,1S <J .(cUl <f* eOJ! X/S <U <4rd O! r- Ir'rtr3* ,c "*i CL xn ' SQXU_ XU XU +S( A> 01 XU 4-> CO r"*" <c ,10 0) d ;b I0j .3 VS 0 ;h W S rC^Of* SO OS L--O .7~ OS CO CO CO GO to ob <0 IT) r>. -VO vo CM co 1 * CO Os fCtoO 00 co CCMO i i fmim g--m to CO t CO <30 F*S CCMO to CM 1 VO vo CO CO CO CO GO 'CM to x?x -- 1-- tcop r-!" <c CM CM CO CO XM >C--M .1 vs XU C <b r-f <d -TP. ',S<u 3 tu XI . 3 vs CO QJ CO Cr--O r>> CM j-- CM CM e-- J CO OS co CO 1 itJ '$. ' Ps -- o ! CO VCOO :'feC ' _OS -ro ' ?** CO CO CM CO o GO r-- c 3: 'ijr***1 o 4-> i'iii--si' C o |>|L. o Q i'iljio [CD |fe. i'/. r-> CO CO r> to t CM t-- CO VO CO t CO <0 CM CO CO CM XoUs < . CM L*O -- sJ* CO LT3 CM .1 to CO UJ to ** vt VO -ttoo JO XU s~ to o to t= - DUP040007280 60 Table 24, Comparative Inter-S candinavian check of Pb-B determina tion, Values expressed as pg/lOO ml Spring 1972 Spring 1973 Mean of 8 laboratories 1# 14 51 85 .85 87 7 8 26 40 76- 00 0 1 VO Range of 8 laboratories 10 - 18 . 9 - 17 44-61 80 - 95 81 - 93 5 - 13 5-17 24 - 41 38-51 74 -104 Present value 17 17 61 95 93 94 12 12 31 44 82 Table 25. Inter-Scandinavian accuracy check of Pb-B determinetion. Values expressed as pg/lOOmml Calculated values bead added Mean of 8 Range of 8 Present laboratories laboratories value Spring 38,4 38 31-44 44 1972 77 72 67 - 78 78 77 72 65 - 76 76 77 74 67 - 79 77 "' 'j Spring T9 21 18 - 30 19 1973 32 34 29 - 40 ' 32 68 72 66 - 93 70 DUP040007281 :=' ,'.j - . S3 -ti.-.'-.i--sr.s.. . . ... .* *:.***. 59 - 7.2.3. Collection of biological data On choice of the time for collecting biological samples, attention was focused upon two determining factors. First, it was assumed that the streetsweepers1 springclean of the streets was finished by the end of April, and implied a maximum exposure to street dust. Secondly, the possibility of seasonal variation had to be excluded. The streetsweepers were thus examined concomitantly with the down town group, half of the suburban group and the Pertunmaa (dietary survey) group from the end of flay through the end of June 1972, and the Haapajarvi-Pyhajarvi group in August 1972. For practical reasons examination of the other half of the suburban group had to be postponed until June 1973. The policemen were examined as early as in November 1971, however. ^" Blood samples were collected , and Pb-BALAD, the Hb, and the PCV , were determined in the manner described earlier (section ). -Pb-B samples were deep-frozen, and stored until all the samples had been collected by June 1973. 7.2.4. Analytical methods All of the Pb-B samples, except for those of the 29 policemen , were inter-mixed and analyzed in series made up by proportional amounts from each group, for the avoidance of systematic errors The method error from duplicate measurements was 1.1 pg/TQO ml. The results of the accuracy control program of the eight Scand inavian laboratories with reference to the time of analysis of the Helsinki Series are accounted, for in Tables 24-25, and the corresponding values obtained in the comparison provided by the AS.ARCO laboratory are given in Table 26, the ALAD assay showed a method error from duplicate measurements of 18.4 pnol PBG per liter RBC, The methods applied for the analysis of Pb-B, ALAD, particulate lead in air, Hb and PCV have been described in section 5.4. DUP040Q07282 62 3 of 0.43 yg/m Seasonal fluctuations are observable in monthly means, with a tendency towards lower values during the summer months, and achievement of the highest values in the autumn and winter months. Table 27, Monthly and yearly mean values of air-suspended partial- 3 late lead in Helsioki, Values expressed as yg/m . Numbers of sampling sites refer to areas as follows: 1 - down town, 2 = mixed industrial-traffic-residential, 3 and 4 = suburban Period of sampling. Sampling site Ho, 1234 1971 November December ' 1972 January February March Apri 1 May June July August' September October _x) 2.20 1.70 1.80 1,20 1.80 0.74 0,87 0,68 1,10 1.40 1.55 1.30 1.30 0.97 0.38 0,83 0,92 0.59 0.90 0.85 1,00 1.10 1.40 1,20 1.50 1.20 0,67 0.80 0.91 0,67 1,02 1.18 1.13 0.46 0,76 0.62 0.33 - - 0.16 0,18 0.47 0.52 Annual mean 1,32 0.90 1.05 0,43 ^Stroke denotes omission of sample DUP040007283 61 Table 26. American accuracy check of Pb-B determination in 1972, Values expressed as vg/100 ml. Sample ASAP.C0X`* Present value value Sample ASARC0;:^ Present value value 1 21 12 14 43 53 .2 12 10 15 57 47 3 19 19 16 . 43 55 4 70 86 17 8 9 5 .54 . 73 18 77 6 6.6 74 19 8 8 7 57 64 20 10 8 8 64 77 21 15 15 9 76 79 22 18 13 10 64 71 23 6 9 n .54 63 .24 11 12 12 49 60 25 7. 8 13 57 .72 26 10 1.0 American Smelting and Refining Company, Utah, U.S.A. 7.3, Results 7,3.1.Lead in air Monthly and annual mean values for lead in urban and rural air are listed in Table .27, The highest annual mean value of 1.32 ug/m3 was measured at the Helsinki downtown sampling site; this is about 50 times the rural yearly mean value of 0.025 ug/m . The monthly means at-this urban sampling, site ranged from 0.68 to 2.20 ug/m3 , o while the rural monthly mean never exceeded .0.06 ug/m , The sub urban sampling site 3 displayed a higher yearly mean than did sampling site 2. The Otaniemi sampling site had a yearly average DUP040007284 Table 28. Blood lead levels of d iffe re n t urban and: rural population groups. Values expressed as ygflOO ml o f blood. -64 Helsinki Down- Su b town urban l ** :id > JZ J- C>l .,:`iidrj M3 i> <<0n flO M d1 cOm id 02 e- -- c X+4 3 <32 02 4- > a ai J.n3 t. 3a> G. i'* -* ro is rr in cvj CO , !-* *- C j3ai .Ciqd 3u *-- CO N Ip <r cvi ip o CM v> . <u ! 'id S : 03 ; U- :W r?>. *u * sr c_z X|J oo o +-> -to o N CO N CO n IS- - +00i.J2) xe<CUyJx t/) VI ?r sO r(m*b |Ow CO JO 'd1 -- in lrO*r> i. o.01) ;|Lil ro-- ,C 0> Q S 11111 j1 :i:JJiSd *i>r-f >>*d Q.--r 11 iIt Pertunmaa ( diet survey) Vi d Z I CO 1 00 CM CO LO Oi | CO r-- VO CO irs d M IO CO CO .|W CO --04 r* CO VO * CO cm & T0iO/3l VI S3 . Q. vj 03 3OCL Pi Co I* 4-> -fd OCL Q. id TP . JcOd 'i. C+4 l 4- uio-$ +O3 3 O Vi 4<s0i-u1-i .u<0<ouy). +J 3S oo vi CO r-- vo .<) f n <n ICO CM <D O 4>. in to?X * - *a--O0Ur112.* c .0s3 LO !co. <o CM r- CQ cm p O cm X <3 *4 CO UJ CL i . -- z tx d c x 5 H jCO -r- :<d <T Pi .m CO CM CO <c ." * r-- CM fim. CM <a Q S-. CM 00 CM O VO 3 JO CO CO r~ CM CM r> ts. f-- 3 r*s CM to 4- 00 CO O Xi IS. 4CT-O!B CO O C 3: <o CM r t-- Pi irn--" o G c/i S_ 02 CL 03 0) 5 VO 00 Pi CM V) IT- in +4 02 CM fd* ro"4 02 S~ 44 CO : r-" < CO in CM VO 00 CO co LO CM cr> CM CO in r- c: id O l. f>. o CO CM 5P 3 PO CM C3 in CO J3 o CM LO CO 3 CO c . jfc o 44 c o o LO .hm*B ro4" .00 ra-i M* CM in LO 'rL--O l/l : Sa>O- : 03 03 - .301 LO CO r^ LO L0O0* sJOi 44 <y +os4~> . 00 CM CO CM VO z IX G CO *.r- e X <d & D U P040007285 63 . 7.3.2. Lead in blood Table 28 lists the mean Pb-B values of the different population groups, together with the standard deviations of the means and the ranges. The most conspicuous feature of the results is that no subgroup displayed a mean Pb-B value exceeding 13,5 g/lOG ml. The highest mean values were found in the groups of policemen and male streetsweepers, i.e., 13.5 and 13.3 ug/100 ml of blood, respec tively. Both are higher than the means of the other urban male groups. When the male streetsweepers were tested for significance against the male downtown group, they yielded a t-value of 3.64, corresponding to a p-value of <0.001. The level of significance was similar when tested against the suburban males (t = 4.23, p <0.001). No statistically significant differences were found between downtown and suburban or rural males. The rural males had higher Pb-B values than the suburban males (t = 2.31* p <0.05). Throughout, the Pb-B values of the females were lower than those of the males. The highest mean was exhibited by the 11 female streetsweepers; however, this group was small, and has consequently been omitted from the statistical calculations. Surprisingly, the suburban females exhibited a mean value that somewhat exceeded those of the other female groups. This diversity was statisti cally significant when tested against the downtown group (t == 2.74, p <0.01), the Pertunmaa group (t - 4,10, p <0,001), and the Haapajarvi-Pyhajarvi group (t = 2.84, p <0.0-1 ), Only insignificant differences were apparent between downtown and rural females. For elucidation of whether any dependence existed between the finding of unexpectedly high lead concentrations in air at suburban sampl ing site No, 3, and the higher Pb-B values of the suburban females, a subdivision was made of the suburban group. Comparisons were drawn between the population living within one kilometer of sampl ing site No. 3 {Pohjois-Haaga), and all of the other suburbanites (Table 29). This comparison revealed that the mean Pb-B value was higher for the fjoh|oits-Haaga groqp than for the others, and applied both to maids and to females. The arbitrarily-composed DUP040007286 66 Table 31, Significance testing of differences between erythrocyte ALAD activity levels of Helsinki target groups. Males tP Females t. P Streetsweepers vs. downtown Streetsweepers vs, suburban Downtown vs. suburban -9.37 <0,001 -5,13 <0,001 1.51 >0.1 . -6.37 -5,59 1.72 <0,001 <0,001 * 0.08 table 32, Correlations between erythrocyte ALAD activity and Pb-B concentration after adjustment of the upper Pb-B limit at varying levels, y * mean values of ALAD activity, expressed as unol PB.fi/h/1 RBC. x = Pb-B mean values, expressed as yg/100 ml. Pb-B < IS <14 < 13 <12 < 11 < TO >9 N 357 335 306 .281 241 197 145 y 1050 1.05.6 1064 1078 1097 1104 1135 X 10.3 10,0 .9.6 9.3 8,9 8.4 7.8 r -0.32 -0.32 -0,32 -0.27 -0,20 -0,23 -0.13 P < o.ool < 0,001 < 0.001 < 0.001 < 0.01 < 0.001 > 0.05 No influence of age on the Pb-B levels or the ALAD activity was de tectable among any of the groups in question. This also applied to cigarette smoking with the exception of the streetsweepers' group, in which a difference of Pb-B mean values was found between cigarette smokers and nonsmokers over 45 years of age (Table 33). The differ ence was statistically significant at the 5-percent, level (t = 2,37). The ALAD values showed a slightly smaller difference between smokers and nonsmokers in the older group. No such differences were found in the younger group, 44 years of age of less. DUP040G07287 group of ''other suburban" females did not differ from downtown or Haapajarvi-Pyhajarvi females, but still had a higher mean than the Pertunmaa females. The Pb-B values among Pohjois-Haaga males and females are of the same order of magnitude as the Pb-B values of the streetsweepers. Table .2.9, Lead in blood of suburbanites of Pohjois-Haaga, com pared to other suburbanites Males Pohjois-Haaga Other sub urbanites . N8 28 y 13.1 10.0 so 3.2 2.3 t 2.56 p <0,05 Females Pohjois-Haaga Other sub urbanites 27 53 10.9' 9.2 3.4 1.9 2.4! <0.05 7.3,3, Erythrocyte A-ALAD activity The ALAD values are listed in Table 30, for methodological reasons, the ALAD values of the policemen were omitted; these had been ana lyzed before the current modification of the ALAD assay was taken into use. The streetsweepers have significantly lower ALAD values than the downtown and the suburban group, whereas only minimal differences exist between the downtown and the suburban groups. The results of significance testing between the groups are indi cated in Table 31. The males also had Tower ALAD values than the females (t - 5,55, p <0.001). In this series, the relationship between ALAD and Pb-B yielded a correlation coefficient of r = -0.37 (p <0.001, N = 4T9, range 4-29 ug Pb/100 ml). Interestingly, this negative correlation was still statistically significant when all of the Pb-B values over 10 ug/100 ml were omitted from the calculations (r = -0.23, p <0.001, N = 197) (Table 32). DUP040Q07288 68 from traffic. Dependent upon the wind direction, these sources may have been: Helsinki main incinerator, at a distance of about 5 kilometers east of Pohjois-Haaga, the Tikkurila lead plants, situated about 10 kilometers north east of Pohjois-Haaga, a lead pigment plant at a distance of 1.5 kilometers west of Pohjois-Haa ga and the Haaga 3 power station in Pohjois-Haaga. Mattson and Jaakkola (1974} have suggested that in particular the Helsinki main incinerator, but also the lead smelteries in Tikkurila (sec-* tion 7) may significantly contribute to the Helsinki Pb-A, and especially to that of Pohjois-Haaga. The Pertunroaa male group displayed Pb-B values exceeding those of the other male groups of the general population. This can scarce ly be attributed to dietary variations, since the mean of the Per* tunmaa female Pb-B values was, on the contrary, the lowest of all groups. However, the Pertunmaa male group differs from the other male groups in one respect: they are almost exclusively workmen, small freeholders and 1umbermen frequently using mechanical equip ment such as chain saws. This structural difference between the groups was unavoidable. The other groups of the general popula tion has satisfactory similar structures; they were locally stable, wage-earning groups of approximately equivalent socioeconomic status, spending the entire day in the vicinity of the air sampl ing sites, and mostly working at ground floor or first floor level. There is little reason to believe that cumbersome random or sys tematic sampling would have offered any advantage over the "chunk" sampling employed. Although dietary differences might exist be tween urban and rural groups, the possibility of systematical differences within Helsiijiki is unlikely. The possibility that the analytica] techniques might entail systematic errors was coped with by the intermixture of all samples, and the introduction of similar proportions from each group in the analytical runs. It is probable that women are more suitable than men when it is a matter of assessing differences between the environmental exposure of varying population groups. Although special care was taken to DUP040007289 J 1 r-.ii Hi i \ ... V'.*i 4'. 67 table 33.. Effect of cigarette-smoking on Pb-B and erythrocyte ALAD activity in Helsinki ,streefsweepers {Rb-B values expressed as Ug/IQO ml, ALAD as PBG/h/1 RBC) Pb-B ALAD <45 years of age >45 years of age smokers nonsmokers smokers nonsmokers ' N " 13 15 29 25 X 12.9 12.5 14.9 12.2 SO 2-3 4.3 5.2 2.9 t 0.30 2.37 p >0.1 <0.05 :N 13 15 29 28 X . 814 846 . 751 852 SD 177 ' 254 216 204 t -0.39 -1.82 P >0.1 =0.08 7.4. Discussion The most striking result obtained is the low level of Pb-B found in all the groups. As a whole, the mean values for the urban and the rural population groups are about the lowest reported Pb-B values for general populations.. It is, however, difficult to achieve a satisfactory degree of comparability to other studies in the absence of inter-mixing. The analytical validity of the low values will be appraised in the "General Discussion''. The absence of differences between rural and urban Pb-B levels also arouses interest. Wo differences whatever were apparent between the downtown and the two rural population groups. The Pohjois-Haaga group exhibited unexpectedly high Pb-B values. The Pb-A mean values of Pohjois-Haaga were also surpriginsTy high, approximating to the downtown levels. In all probability these are attributable to at least four lead-emitting sources apart ! 1 : i ` :A DUP040007290 70. The.AL.AD assay proved useful in .discrimination between separate . groups whose Pb-B levels differed to a small but measurable ex tent. The negative correlation between Pb-B and ALAD appeared, furthermore, to prevail at extremely lew .Pb-B levels. The ALAD test is discussed in more detail in section TO.3. 7,5. Conclusions ^ The Pb-8 levels of ail the groups studied were 1c m, No differences were observable between Pb-B levels of downtown and rural residents despite the fact that the Pb-A concentrations in Helsinki' were 5p times as great. The Pohjois-Haaga Pb-B levels were slightly higher than the downtown levels, although similarity was found in the Pb-A concentrations. The difference may have originated in: 1) chance, 2) higher exposure to dustboroe lead for the Pohjois-Haaga popu lation, or 3) different emitting sources producing particles with different characteristics (chemical composition, shape, solubility) which may affect the rate of absorption (Lawther et al.1972 a,b).None theless, Helsinki traffic alone does not increase the Pb-B levels of the general population to an extent that is significant in practice. The exposure to exhaust gas and dust of the traffic policemen and the streetsweepers is followed by a measurable in crease in Pb-B levels. DUP040G07291 69 exclude additional exposure of occupational origin, men seem to be subjected to a higher risk of undergoing additional exposure, i. probably through work or leisure-time activities. The Pb-8 values Of the Pohjois-Haaga females seem to indicate a measurable effect of Pb-A amounting to about 1 pg/m^ whereas the downtown group did not exhibit any effect of this kind. Nonetheless, it must be emphasized that the use of a few fixed sampling devices is an in adequate method for assessment of the exposure of an entire popu lation group. Furthermore, in population studies it is difficult to cope with interindividual variations of dietary lead intake that mask the influence of low lead concentrations in ambient air. The finding that the streetsweepers had rather higher Pb-B values is consistent with earlier reports {Lefrnert et al, 1970, Lprant and Svoboda 1973). Cigarette smoking was not found to exert any effect upon Pb-B within the groups of the general population. Only in the streetsweepers'group over 45 years of age did the smokers show higher Pb-B values than rionsraokers, No such difference was discernible in the younger age group. The literature is controversial on this point. Some investigators have reported higher Pb-B levels for smokers than for nonsmokers (Hofreuter et al. 1961, Ludwig et al. 196.5, Tapper and Levin 1972), while others have been unable tp de tect such an effect (behnert et aT. 1967, Caines et al.. 1972, McLaughlin and Stepps 1973). It seems probable that in itself the inhalation of tobacco smoke does not have a measurable effect on Pb-B levels. The differences reported are probably attributable to the ingestion of particles from contaminated fingers. The occurrence of the difference in the older groups alone presumably arose from hygienic differences between the age groups, a longer period of lead accumulation, and decreased mucociliary activity of the smokers. i DUP040007292 72 8.2. Material and Methods 8.2.1.The Tikkurila area Tikkurila is a mixed residential and industrial area, fifteen kilometers north of Helsinki, two secondary lead smelteries, two storage-battery plants, one battery factory with a small foundry, along with a group of soldering workshops, operate within this area (Fig. 3). The arable land close to lead smelter A (Fig. 3) belongs to the Government Agricultural Research Center, whose in vestigators found in 1970 that the Snow, and the needles of conifer trees, had an exceptionally high lead content which markedly in creased as the smeltery was approached (Lakanen and Ervio 1971). A later report disclosed heavy lead pollution of the soil sur rounding the smeltery {Ervio and Lakanen 1973). Smeltery A was founded in 1935, From 1950, when the filters went out of order, until 1970, the smoke discharged from the furnaces was not purified, the amount emitted in 1970 was estimated by the plant management to be 22 tons, expressed as metallic lead, 'on the basis of the amounts regained after the installation of purification equipment in 1971. This amount is equal to 25 per cent of the calculated total emission from Helsinki traffic (Mattsson and Jaakkola 197.4), 8.2.2. Target population Random sampling of the population over fifteen years of age, and living not further than four kilometers from either one of the smelteries, was carried out in the spring of 1970. The 621 per sons so selected were invited by letter to participate in the Study; of these, 334 responded, and were examined between June and November 1970, All those with even the slightest present or previous occupational exposure to lead were excluded from the DUP040007293 r* ;v : Q/ 71 8. BLOOD LEAD LEVELS AND ERYTHROCYTE A-ALA DEHYDRATASE ACTIVITY IN RESIDENTS AROUND LEAD EMITTING INDUSTRIES 8.1, Introduction It is well documented that lead smelteries contaminate the soil, air, water, and plants around them (Alloway and Davies 1971, Kerin et al. 1972, Kerin 1974). When this study was planned, the data indicating an increase In the lead absorption by people living in such vicinities was scanty (Oyangyren et al, 1966}. More recent studies have reported increased absorption in populations living near Lead-emitting industries, as has become evident from rises in the Pb-B and Pb-U (Djuric et al, 1971, Secchi et al, 1971, Martin et al. 1974, University of Toronto 1974) and from the in creased lead excretion following provocation with CaEDTA (Djuric et al, 1972), Extreme conditions have increased the excretion of ALA-U into the urine (Djuric et al, 1971), This is of partic ular importance, as ALA-U is a parameter of lead toxicity, further more, the increase in this parameter does not become measurable until the Pb-B rises above 40-50 pg/100 ml (Selander and Cramer 1970, Tola et al> 1973). No data on ALAD of populations living near lead smelteries were available when the present study was started. However to judge from the negative correlation obtained between Pb-B and ALAD of occupationally unexposed subjects (Hernberg and Nikkanen 1970), it seemed likely that the ALAD assay would -be sufficiently sensitive to reflect the anticipated differ ences in lead .exposure of the1 population living in an area characterized by industrial lead pollution. * 1. ' DUP040007294 74 Table 34. Distribution of the Tikkurila series by age and sex.. Age 15 - 24 25 - 34 35 - 44 45 - 54 55 - 64 65 or more Males 24 17 29 24 20 7 Females 21 26 39 34 25 27 AM 45 4.3 68 58 45 34 Total 121 172 293 Tabl e 35, Cigarette-smoking habits of Tikkurila population Cigarettes daily >20 10-20 <10 Pipe or cigars Nonsmokers Wales Females 11 21 14 16 12 3 ** 67 149 All 11 37 26 3 216 8.2,3. Methods The procedures of collecting biological samples and the analytical methods .have been described in section 5. Pb-B analyses from Tik kurila survey showed a method error of duplicate determinations of 2.0 Pg/100 ml. The results of the Inter-Scandinavian accuracy control of the Pb-B assay are listed in Table 6. The method con trol performed by the ASARCO laboratories at the same period of time is accounted for in Table 7, At that time new spiked stand ards were prepared every third month. The ALAD determinations displayed a method error of duplicate analyses of 3.6 pmol PBG per liter RBC, DUP040007295 73 . Fig. 3. The Tikkunla area. A and B = secondary lead smelteries, C - battery factory with a small foundry, 0 = accumulator plant, E = soldering workshops, F = accumulator plant, G = Agricultural Research Center. The isopleth numbers are equivalent to monthly dustfall lead within the marked zones, expressed in grams per 100 m9 . study. In all, 16 persons were omitted for this reason, along with a further 25 persons for other reasons such as clotting of the blood sample, or their moving from the district. Of the remaining 293 ; persons, 121 were males, and 172 females. The age distribution is presented in Table 34.. In all, 30 males and 23 females were work; . Ing outside the district, while 91 males and 149 females were both residing and working within it. Of them, 12 males and 6.2 females, mostly housewives and pensioners, spent the whole day at home. The major part of the population studied {239 persons.) was made up of . ']; inhabitants living around smeltery A, The cigarette-smoking habits : , are indicated in Table 35. DUP040007296 76 0.07, p >0,1). If only the 59 subjects living around smeltery A and spending the whole day at home are Included, the correlation between Pb-B and the distance is even stronger (r - -0.62, p <0.001), as is observable from Fig. 6. The correlation of ALAD with the distance in this group was of the same magnitude as that for the entire population (r = 0.28, p <0.05). (Log. scale) Fig. 4. Correlation between blood-lead concentration and distance of habitation from the emitting source (smeltery A). DUP040007297 75 the dystfall lead survey was effected in Tikku.rila between October 6th and November 6th. The dustfal1 was sampled by SO collectors, spread over an area of 40 square kilometers. Arbitrary isopleths for total leadfall were drawn, and the Pb-B and ALAD results were correlated to the so-formed zones representing varying degrees of leadfall. The leadfall isopleths are illustrated in Fig. 3. In the handling of the data* consideration had to be given to the neighborhood of lea*l smelter B being sparsely inhabited, with practically no settlement within one kilometer of the chimney. Consequently, the 54 persons from.this neigborhood are included merely in those calculations in which the distance to the emitting source was not an essential feature. They have also been omitted from the correlations between blood lead .concentrations and total leadfall. Logarithmic transformation has been applied for calculation of the means and standard deviations in view of the skewness of the distributions. 8,3. Results Lead smeltery A exerted a distinct effect on the Pb-B's of the surrounding population; this is apparent from the negative cor relation between those values and the distance of habitation from the emitting source (r =-0.41, p <0.001) (Fig. 4), This effect was more pronounced in the females (r = -0,49, p <0,001) than in the males (r = -0.23, p <0,05). The increased average lead ab sorption in people living near the smeltery was accompanied by a decrease in their erythrocyte ALAD activity. However, Fig. 5 indicates that the correlation with the distance from the source was weaker than that for Pb-B (r = 0.21, p <0,01), The .correla tion was, furthermore, almost entirely attributable to the fe males (r = 0.28, p <0.01), since, on an average, the ALAD values of the males were similar irrespective of where they lived (r = 78 (Log. scale) Fig, 6. Correlation between blood-lead concentration and dis tance of nabitation from srneltery A, as concern? only the 5.9 subjects who spent the whole day at home. The means and standard deviations of the Pb-B's and ALAD activi. ties in the whole population have been tabulated in Tables 36 and 37, The mean Pb-B for men is higher than that for women (t =* 7.02., p <0.001). A statistically significant negative correlation be came evident between the Pb-B and the ALAD values (Fig. 8). The correlation was of the same order of magnitude for males (r = -0.32, p.<0.001) and females (r = -0,34, p <0,001). No relation ship was found between Pb-B and age. Smokers had slightly higher Pb-B values than nonsmokers (Table 38 ). Only males are included in view of the small number of female smokers available. DUP040007299 77 i i ' I Fig. 5, Correlation between erythrocyte ALAD activity and dis tance of habitation from the emitting source (smeltery A}. The results of the dustfall survey are presented in Fig. 3., in -which the isopleth numbers are equivalent to monthly dustfall lead in grams per 100 m2 . The dustfall lead markedly increases on the lead smelteries being approached. A statistically significant correlation is obtained when the Pb-BVs of people living in the different zones, defined by the isopleths, are correlated with the monthly dustfall lead within the .corresponding zones (r = 0.32., p <0.001). The correlation is visualized in Fig. 7 . DUP040007300 80 Table 36. Blood-lead concentrations in 293 inhabitants of the Tikkurila area. Values expressed as yg/100 ml. Males Females Total N X X-SD 12] 18.1 13,6 172 14,3 10.6 .293 15.7 .11,5 x+50 24.1 19,1 21,5 Table 37. Erythrocyte ALAS) activities in 276 inhabitants of the Tikkurila area. Valued expressed as ymol PBG/h/l RBC, N X SB Males Females 115 161 948 271 1031 284 Total ' 275 996 281 Table 38. Effect of cigarette-smoking pii Pb-B levels of the Tikkurila population. Values expressed as yg/100 ml >20 cigarettes a day All smokers Nonsmokers N 11 46 70 X 21,4 19.1 t ----- ---------------- - ----- 2.43 17.6 ------ - P -U Uj t -1.75 ----------------- P --=0,08 DUP040007301 79 Fig..;'7, Correlation between Pb-B levels and monthly dustfall lead. the numbers on the abscissa are equivalent to monthly dust2 fall lead in grams per TOO ni . Note log scale on the ordinate a aoct $000 m cl h 1000 0*8 3*. ~ .500 ^^ -i. x .2-SO ^-- X -- X- 2-SD - tog y * 3.12. 34. 0.00859.x.t 0,1260 r, -- 0.35 P <0.001 ,100 10 20 30 40 Pb-B. jig/ lOO ml Fig. 0. Correlation between blood-lead concentration and erythro cyte ALAD activity. DUP040007302 82 that the study was accomplished after the installation of purifi cation devices at smelter A; the Pb-A levels were thus presumably even higher in 1970. Moreover, the tikkurila survey disclosed higher Pb-B values for males than for females. Within this population, however, the mag* nitude of the difference may have been affected by certain fea tures of the material. For instance, smokers, and heavy smokers in particular, who in this study displayed slightly higher Pb-B values than nonsmokers, were more frequent among the men:. Further more, the mean distance to the emitting source {smeltery A) was 880 m for the females, and' only 7.60 m for the males, both factors would tend to increase the differences between the Pb-B levels of men and women. Moreover, if lead content is referred to the PCV instead of to whole blood, the inter-sex difference is diminished from 18 (males) and 14 (females) pg/100 ml whole blood to 3.9 and 34 pg/100 ml packed blood cells, respectively. From the results obtained in this study, it is obvious that the lead pollution originating from the lead smelteries may be suffi ciently heavy to increase the lead absorption Of the surrounding population to a measurable extent. DUP040007303 81 - 8.4, Piscussioo Both the dustfall lead and the Pb-B measurements confirm that under certain conditions the population living around a .lead smeltery may be subjected to lead exposure that definitely exceeds "normal" rural or suburban levels, and that the exposure is increased when the emitting source is approached. The fact that a negative cor* relation was demonstrable between the distance of habitation and Pb-B, stresses that smeltery A was a heavy polluter indeed, since other circumstances tended to weaken such a relationship. First,, smeltery A was not the only source of lead pollution. Several other lead-emitting plants are located in the district, and in addition, highway and ordinary suburban traffic contribute to the total amount of pollution. Secondly, only part of the people spent most of their time at home, or even within the district. This was probably the more important factor, and explains why the use of monthly dustfall lead zones as a reference, instead of the distance of habitation, did not greatly improve the correlation. The same explanation is apparently also valid in regard to females haying stronger correlations than males between the Pb-B and the distance of habitation from smeltery As of the 59 persons living around that smeltery, and spending the whole day at home, 49 were women. When consideration is limited only to those spending the whole day at home, a substantial improvement is observable in the correlation between Pb-B and the distance. The increased lead exposure was not only evident as a rise in Pb-B; a partial inhibition of the ALAD activity was also demonstrable. The do.se -response effect for ALAD was not so marked as that for Pb-B, however, and was demonstrable in women only. For technical reasons the Pb-A in Tikkurila could not be measured. However, a study conducted in 197.3 On particulate lead in the air at Tikkurila showed a maximum monthly mean of 6.4 pg/m of air in the vicinity of smeltery A. The mean concentration for six months was 1,8 pg/m (Vornamo 1974). It must, however, be emphasized DUP040007304 Percent 34 of separate series :1 .{ t m^A .7-.T y. '-. i r' -i Fig. IQ. Cumulative percentage distribution of female Pb-B values of separate series DUP040007305 9. COMPARATIVE RESULTS The results obtained in the separate groups have been combined with a view to the achievement of greater clarity. Table ,39 illustrates the annual mean Pb-A levels of different rural and urban air sampl ing sites. The downtown sampling site exhibited a yearly mean 50 times as great as the rural mean. The lowest annual mean in Hel sinki was obtained at the suburban Otaniemi sampling sites this value exceeded the rural mean to the extent of nearly 20 times. Table 39. Annual mean concentrations of air-suspended particulate lead at urban and rural sampling sites. Values expressed as ug/m3 . Helsinki sampling site numbers refer to areas as follows: 1 = downtown, 2 =\nrixed industrial- -traffic-residential, 3 and 4 - suburban Sampling site Annual mean Pertunmaa Helsinki 1. 2. 3, 4, 0.025 1,32 0.90 ; 1.05 ' 0,43 The cumulative percentage distribution of Pb-B values of men and women are presented in Figs. 9 and 10, respectively.. The female streetsweepers have been omitted from the figure, in view of the smallness of the group. The distribution curve of the Tikkurila group shows the most apparent difference from allthe other groups, throughout revealing Pb-B levels that exceeded, at a statistically highly significant level, all of the Pb-B levels disclosed by the other groups (Table 40). The testing of significance between the groups was done by means of the Kolmogor.ov-Smirnov test, because of the skewness of the Tikkurila distribution. In general, the skewness of the distribution increases with increasing Pb-B values. 86 - not been taken into account (Nozaki 1966), and the shape and the chemical composition of particles may highly alter the figures of absorption (Lawther et al, 1972 a, b). It can be seen from Table 41 that the total daily intake of lead is distinctly below the provisional tolerable weekly intake of 3 mg per adult person pro posed by the Joint FAO/WHQ Expert Committee on Food Additives (FAQ/ WHO 1972 ). Table 41. Dally lead intake and absorption at an annual mean air 3 lead concentration of 1.3 yg/m . Values expressed as micrograms of lead. Source Food Beverages Air Daily intake Mean Range 169 71 - 310 35 -4 - 116 20 11 - 33 Daily absorption Mean Range 14 6-25 3 trace* - 9 7 4 - 12 Total' ,224 86 - 459 24 10 - 46 * Trace denotes <1 pg The hematocrit values for all groups are given in Table 42. No inter-group differences of statistical significance existed. The mean hematocrit values for men ranged from 45.5 to 46.2 percent, and those for women from 41,5 to 42,4 percent. The hemoglobin mean values (Table 43) varied between 14,4 and 1.5.5 g/10.0 ml for men, and between 12.9 and 13.9 g/100 ml for women. The hemoglobin values of the TikkuriTa males and females being significantly lower than the others was considered to be due to systematic errors of the analyses; this group was the only one analyzed by non-professional laboratory personnel. A true difference between the groups seems less intelligible. DUP040007307 85 Table 40. Significance testing for the Tikkurila Pb-8 levels ascompared to other population groups. Males 0P Females Dp Tikkurila vs,: Streetsweepers Pol i cemen Downtown Suburban Pertunmaa HaapajSrviPyhajarvi 54.3 50.2 64,0 74.3 57.9 '- <0.001 <0.001 <0.001 <0,001 <0.001 - 47.1 - 71.0 56,1 51.5 70.1 <0.05 - <0,001 <0.001 <0.001 <0,001 The Helsinki downtown population was subjected to the highest con centrations of lead in ambient air. An attempt has been made to estimate the total daily amount of lead absorbed by this popula tion group, taking into account the lead inhaled from the air, and ingested with food and beverages (Table 41). In view of the great number of meals eaten outside homes, and the voluntary partici pation of entire households being a prerequisite, a dietary study in Helsinki, identical with the Pertunmaa survey, was considered to be impracticable. Thus the assumption-was made that no im portant differences existed between urban and rural dietary lead intake, A gastrointestinal absorption of 8 percent, and an average amount of inhaled lead reaching the blood stream of 37 percent at 3 a respiratory rate corresponding t-o a daily 15 m of air, were applied. The Pb-A concentration used in the calculations, was 1.3 jjg/nr . The .calculated mean absorption of about 24 yg Pb/day is distinctly lower than the values obtained by Kehoe (1.961a) and Schroeder and Tipton (1968), However, -it should be emphasized that the value conceals large inter-individual variations with respect to absorption (Hursh and Su.omel.a 1968); furthermore, the degree of physical activity altering the respiratory volume has DUP040007308 88 10* GENERAL DISCUSSION 10.1. Validity of the Pb-B assay When thi$ study was begun, the Pb-B assay was known to be vulner able to systematic errors. As interpretation of the results would be completely dependent on the validity of the Pb-B assay, great | care was taken to ensure its accuracy and precision throughout the work (section 5.4.)> the precision appeared to be on a high level during all of the surveys. The method error of duplicate measure ments reported by the laboratories (1.1 pg/100 ml), somewhat lower than that noted for a set of .26 duplicate samples analyzed unbe known to the laboratory personnel (1.7 ug/100 ml), is consistent with the findings of Berlin and his colleagues (197.4 a),who suggest ed that laboratories tended to reject outlying results when re porting. All of thp Pb-B values reported here were mean values of two parallel determinations; if the discrepancy between dupli cate measurements exceeded .5 ug/100 ml, the analyses were repeated. This procedure probably accounts for the differences referred to above. in regard to accuracy, it is observable from the Inter-Scandina vian comparison corresponding to the period of the Pertunmaa Pb-B study (Table 6) that at the time our method showed somewhat higher Pb-B values than did most of the other laboratories; our values were systematically higher than the mean values of the 8 partici pating laboratories, and furthermore with several samples our values were the highest of all. The agreement between results obtained by the ASARCO laboratories and those of the Institute of Occupational Health was much closer than is usually found in inter-laboratory .comparisons (Keppler et al, 1970, Berlin et al. 1972, 1974a){Ta.bl.es 7 and 26). The accuracy control of the period of the diet survey and the Helsinki and Haapajarvi-Pyhajarvi surveys also shows that our Pb-B values were slightly higher than the mean of the Scandinavian laboratories and the ASARCO labora- 5 j ; j A i \ f ! DUP040007309 87 Table 42. Hematocrit value of different urban and rural population groups Tikkurila Males Females Helsinki Males Females Streetsweepers. Males' Females Traffi c pol i cemen . Mai es Pertunmaa Males Females H X SD range 113 45,7 166. 41.8 182 , 45.8 121 41.8 85 46.1 1.1 42.2 28 46.2 239 45.5 254 41.8 2.8 2.6 ' 2.8 2.5 2.8 2.1 3,2 3.5 3.5 38-53 36-50 , 38-54 33-49 38-52 38-46 34-51 36-57 27-57 Table 43* Hemoglobin concentration of different urban and rural population groups. Values expressed as g/TOO ml. N X SD range Tikkurila Males Females Helsinki Mai es Females Streetsweepers Males Females Traffic policemen Males Pertunmaa Mai es Females 113 14.4 1.0 : 11,3-16.6 166 12.9 -0,9 11,0-16.2 182 15.3 1,1 11.9-18.0 120 13.7 1.0 11.3-15.9 85 15.4 1.0 13.0-17.5 1.1 13.9 0.6 12.6-14.6 28 14.7 1.2 10.0-16.1 240 15,0 1,2 11.9-18.6 254 13,4 1.2 6.3-17.7 DUP040007310 90 within the biological guide proposed by Zielhuis (1974), and below the roaxiwuni allowable individual values suggested by both Zielhuis (1974) and the U.S, Environmental Protection Agency (1972) {See section 2.5.1.). Only one person, living at a distance of 100 m from the chimney of one of the lead smelteries, had a value that exceeded the proposed limit of 40 ug/100 ml. The narrow range ob tained in this study was probably due to the scrupulous omission of all subjects with possible occupational exposure. 10.3, The ALAD assay in population studies The sensitivity of the ALAD test has been established by many in vestigators (Bonsignore et a]. 1965, DeBruin and-..Hoolboom 1967, Hernberg et al. 1970, Haas et al, 1971, Haeger-Aronsen et al, 1971, Millar et al, 1970, Tola 1973), Moreover, it has repeatedly been shown that the specificity is high (Hernberg and Nikkanen 1972), and the accuracy and precision .are good (Berlin et al, 1972, 1974 b). It has been suggested that the ALAD assay, by virtue of these characteristics, would be suitable for population surveys (Hernberg et al, 1970, Berlin et al, 1972, 1974 b, Berlin and Schaller 1974). Despite the exceptionally low Pb-B levels -found in the present study, the ALAD assay appeared to be suffi ciently sensitive for discrimination between most groups in which the Pb-B levels differed at a statistically significant level. The ALAD test failed to reflect only the differences found be tween the downtown and the suburban females, and differences between the two suburban groups (section 7.3.3.). When the study .was initiated, no experience had been gained of ALAD from popula tion studies, but during its course some researchers reported on their experience in population studies where the ALAD test has been employed. Secchi and his colleagues, for instance, have successfully applied the ALAD test in studies On varying popula tion groups subjected to different degrees of environmental lead exposure (Secchi et al. 1971, 1972, Secchi and Alessio 1974). The Pb-B levels of those population groups from Milan, or DUP040007311 89 tories, although the agreement was close, especially at low Pb-B levels (Tables 24-26). It can be concluded that, if anything, the values reported by the Institute of Occupational Health were sys tematically a little higher than the mean values of the reference laboratories. 10.2. Blood lead levels in Finland The mean Pb-B levels found in the target groups selected to re present the Finnish .general population were throughout among the lowest ever reported (Hofreuter 1961, Ludwig et al. 1965, Holmqvist 1966, Lehnert et al. 1967, Hprluchi 1970, Tepper and Levin 1972), together with values obtained for smaller groups from Southern Sweden (Haeger-Aronsen et al. 1971) and Denmark (Nygaard et al. 1973). Soldwater and Hoover (1967) have also reported relatively low values for some population groups. The low values reported here can scarcely be attributed to systematic errors,, since the yalues were too high rather than too Ipw, as compared to the techniques of the reference laboratories. The only population groups in which urban pollution became evident, as reflected by elevated Pb-B values, were the streetsweepers and the policemen, both of which experienced more exposure than other populations. However, consistently with all other categories, the streetsweepers` values were comparatively low; they were thus only about one half of those reported for streetsweepers in Frank furt :a.M. (Lehnert et al. 197.0) and Vienna (Lorant and Svoboda 1973) The Pb-B values of 15 traffic policemen in Stockholm have been reported to be of similar order of magnitude (fiothe et al. 1973). The inhabitants of Tikkurila exhibited a distinctly higher lead absorption, which was closely correlated to the distance of re sidence to the main source of emission. Nevertheless, it can be concluded that all of the separate groups surveyed displayed percentile distributions of their P.b-B values DUP040007312 .:;-r i s i .Tr 92 An important feature -of the result? was that the negative corre lation between Pb-B and ALAD was statistically highly significant (p <0.001), even at Pb-B levels of 10 pg/100 ml or below. This has a bearing upon the question of whether or not a threshold exists for the inhibitiory effect of Pb-B on ALAD activity. Both the conception of a threshold, and tha_t of a non-threshold have their advocates. However, whether a threshold is obtained or not seems to be a question of the sensitivity and precision of the methods applied. In the comparison of environmental exposure,the Pb-B technique applied currently is the most straightforward method, although it calls Tor advanced equipment and ski lied personnel. On the other band, the AlAp assay is less expensive, less exacting and has a higher inter-laboratory comparability than has the Pb-B method (Berlin et al. 1972, 1974a,b).The only important drawback of the ALAD method is the lack of stability* which means that the ana lyses' should be performed within five hours of sampling (Nikkanen et al. 1972). According to the experience gained in this study, the ALAD assay appears to be a useful epidemiological tool for comparison of environmental lead exposure in various populations. io. 4, Preventive needs for Finland in the light of the present study The results presented here do not indicate any effect of traffic alone on lead absorption by the general adult population. Although the street-sweepers ..displayed an increase in absorption as did the policemen, they cannot be ranked in-the same category as the gener al population, as they are subjected to additional exposure to airand dustborne lead. Even so, the rise in absorption was very small. The relatively higher Pb-B values of the Pohjois-Haaga group were most probably attributable to additional exposure derived from lead-emitting sources other than traffic. This opinion gains sup port from the study by Mattson and Jaakkol a (1.974), who calculated DUP040007313 yJ i-- - i l : ~`i - .. . _{ 91 the rural neighborhoods of Milan,, however, were higher than the commonly reported levels for general populations (see section 2,5.1.). Also, lob and his co-workers were .able to discriminate between a rural and an urban group of schoolboys by employment of the ALAD assay. The mean Pb-B values of the two groups were IS.9 for the rural, and 22.2 yg/100 ml for the urban group (Lob et al. 1972). In contrast, Kennedy and his colleagues (1972) did not discover any relationship between ALAD activities and Pb-B values below 25 pg/100 ml, Valloton and his colleagues .(1973) could not establish a significant correlation between Pb-B levels and ALAD activities in people unexposed to lead by profession; neither did Coulston's team find any inhibition of ALAD in their 18-week chamber exposure study at-3.2 pg Pb/rn of air, although a distinct elevation of the Pb-B levels occurred. However, in an identically designed study at 10.9 pg P.b/m3 of air, a distinct inhibition of the ALAD activity was noted (Coulston et al. 1973 a., b ). These seeming discrepancies are probably attributable to methodological aspects. Close correlation between Pb-B and ALAD necessarily calls for extremely high precision and-sensitivity in both methods. These aspects become even more important when the range of varia tion is very narrow, as is the case in studies of the general po pulation. The validity aspects of the Pb-B have already been dis cussed, and will not be repeated here. In regard to the ALAD assay, the most important feature is standardization of the pH value, which presupposes a stable buffer. Furthermore, all of the researchers referred to above used a pH of 7.0, which according to Nikkanen and his CO-workers (1972) is less sensitive than the 6.8 employed here; however, the highest correlation coefficient was found by Nikkanen And his colleagues at a pH of 6,4, With a view to the comparability between laboratories, it thus seems reason able to recommend the standardized ALAD assay suggested by Berlin and Schaller (1974) for future population studies; the method employs a pH of 6.4, and has been specially developed to suit low-level exposure to environmental lead. | \ t,. : . . DUP040007314 94 lead additives in gasoline cause impairment of the effectiveness of such equipments; thus, further aspects favoring a reduction of lead content in gasoline must be borne in mind (Prescott 1972, EPA 1973). Regardless of the solution that is chosen, the reduction of lead additives will be associated with high costs. The first ob vious step towards a reduction of atmospheric lead pollution should accordingly be directed towards the more easily controllable pollu tion that originates in lead-processing plants, incinerators, power stations and other coal-burning manufacturing establishments. * DUP040007315 93 . a dispersion into the Helsinki air of about 1.0 kg Pb/b from traffic, and a total of about 3 kg P.b/h from the Helsinki main incinerator alone. Since in principle all surplus lead exposure should be avoided, re duction of the lead content of gasoline is a praiseworthy measure.. Nevertheless, the results reported here indicate that the problem seems much less urgent In Finland than in countries with high popu1lation and traffic density, the elimination or the reduction of lead additives will lead to lower-octane gasoline, or necessitate the maintenance of octane ratings by some substitute, or substi tutes, for lead, lower-octane gasoline requires lower compression ratios, which signify a loss in engine performance, and an increase in gasoline consumption; this is an undesirable consequence against the background of energy crises, A loss in performance would in particular affect the relatively small,hi gnly-tuned European cars .the means to preserve the octane ratings by other additives will thus assume major importance. The easiest and least costly way would be that of increasing the content of aromatic hydrocarbons (Boddy 197,2, Campbell 1973). Unfortunately, the content of aromatic hydrocarbons in European fuel is .already higher, for instance,than that in the U.S.A. The implications connected with an increased content of aromatic hydrocarbons in gasoline are probably even more obscure than the continued use of lead. Berlin, Sage-.and Johnson (1974) have re viewed the likely consequences of such an increase. An increase of potentially carcinogenic polynuclear aromatic hydrocarbons in ambient air would occur. Probably, an increase of toxic products, such as eye-irritating ones, would take place as a result of the photochemical reactivity of a number of hydrocarbons. Moreover, a subsequent increase in the benzene content would introduce an occupational risk for all those involved in the handling of the gasoline. Although the emission of hydrocarbons can partly be controlled by the use of catalytic exhaust-treatment devices, the DUP040007316 96 men displayed a mean of 13.5 jpg/100 ml, indicating a slight in crease in the lead absorption. No effect on Pb-B levels of traffic alone was detectable within the general population; thus, no statistically significant differ ences were found between downtown and rural or suburban Pb-B levels. The observation that the pohjois-Haaga subprbanities disclosed higher Pb-B levels than did other suburbanities indicates that factors other than traffic should be borne in mind in assessment of the effect of traffic on lead absorption. The mean Pb-B of 293 inhabitants of the Tikkurila area, at a statis tically highly significant level, exceeded the means of all the other groups, A distinct correlation was apparent between the dis tance pf habitation from the emitting source ( a secondary lead smeltery) and the Pb-B levels . The rise in Pb-B on approaching the emitter was accompanied by a decrease in the erythrocyte ALAD activity. Similarly, there was established a correlation between Pb-B levels and the monthly dustfall lead within the area. The age per se was not found to have any relationship to the Pb-B level.. Ah effect of cigarette-smoking on Pb-B levels was estab lished only in the Tikkurila male population, and the streetsweepers aged 45 years or more, indicating that probably factors other than the inhalation of cigarette smoke itself may explain the de tection of higher Pb-B values in smokers than in nonsmokers. Men in each separate group had higher Pb-B levels than had women. This difference wars not entirely attributable to the higher hematocrit value of men.. The distinctly higher dietary-lead intake for men than that for women probably accounts for part of the difference. The usefulness of the ALAD assay was evaluated within the compass of the Helsinki and Tikkurila surveys. The ALAD assay proved use ful and reliable in the discrimination between separate groups whose Pb-B levels differed to a small but measurable extent. The DUP040007317 95 11. SUMMARY The levels of lead in the blood of the adult general population in Finland were determined during the period dune 1970 - dune 1973. The population groups were selected to represent varying degrees of environmental lead exposure. The possibility of occupational ex posure to lead was scrupulously excluded. The rural population groups were sampled in the commune of Pertunmaa, and the communes Of Haapajarvi and Pyhajarvi; all the urban groups were sampled in Helsinki. In addition, a survey was made of the population living in Tikkurila, a district characterised by its congregation oflead-utilizing manufacturing plants. The concentrations of air-sus pended particulate lead were studied in Helsinki and Pertunmaa; the population groups were sampled from thp geographic vicinity of the sampling sites. By the employmeht pf a double portion method, and a recording period of three days, the dietary lead intake was assessed in 23 rural households in Pertunmaa. Care was taken to en sure the accuracy and precision of the analytical methods, and the Pb-B assay in particular, by continuously checking the methods at experienced laboratories. There was found a mean dietary lead intake of the Pertunmaa popula tion amounting to 204 pg/day (range 89 - 360 ug/day). The mean in take of men was higher (231 pg/day) than that of women (178 pg/day). The annual mean concentration of lead in air in Helsinki ranged 3 from 0.43 to 1.32 yg/m . The corresponding mean at the njral sampling site (Pertunmaa) was 0.025 pg/m . From an international standpoint, the Pb-B levels were low. The highest mean Pb-B value in groups of the general population was disclosed by the rural wale group (12.3 yg/100 ml), and the lowest by the female respondents of the diet survey (7.9 pg/100 ml). A group comprising 86 male streetsweepers from Helsinki displayed a Pb-B mean value of 13.3 pg/100 ml, and 28 traffic-directing police- DUP040007318 : ` ' .... -V VC-\ ' v- .. " ..... i i i .1 98 12. ACKNOWLEDGEMENTS The subject of this study was suggested to me by Sven Hemberg, M.D., Associate Professor, and Scientific Director at the Institute of Occupational Health, my friend and teacher to whom my sincere thanks are due. During the course of the study, his never-failing enthusiasm and advice gave me great encouragement. I am deeply grateful for his constructive criticism while the final report was being prepared. I am also greatly indebted to Professor Martti J. Karvonen, M.D., Ph.D., former Chief of the Institute, and his successor, Jorma Rantanen, M.D., who have both taken great interest in the investigation and have placed all the facilities of the Institute at my disposal. I am especially indebted to Professor Ilari Rantasalo, M.D,, for the interest he has shown, and for the valuable help he Has pro vided in the final! stage of the study. I wish to thank Professor Kimmo Aho, M.D., for the valuable and sound criticism I received during the preparation of the manuscript. Gratitude is due to Miss Raili Vilhunen, M.Sc. (Eng,), and Mr Jorma Nikkanen, M.Sc,, for their supervision of laboratory analyses, and to Mrs Hilkka Jarventaus, who in this part of the work gave skilful technical assistance. I am also obliged to Professor Arvo Laamanen, Ph.D., Mr Aulis Ryhanen, M.$c. (Eng.), and Mr Hannu Vornamo, M.Sc., for their cooperation in connection with the aerometric surveys. My thanks are due to Acting Professor Maija Pekkarinen, Dr. Agr. Sc., for the invaluable help she provided in the planning of the diet survey, and to Miss Lea Turpeinen, M.Sc., for supervising the . collection of food samples; this exacting collection work was done by Miss Pirjo Paattiniemi and Miss Pirjo Makela, to whom my gratitude is also due. DUP040007319 negative correlation between Pb-B and ALAD activity was found to prevail at a statistically significant level still at Pb-B levels of ID yg/100 ml or lower.. DUP040007320 100 13. REFERENCES Alloway, B. j. and Davies, B.E, trace element content of soils affected by base metal mining. Gepdenna 5:197,1971. Anonymous. Leading article. Lancet 2, 1967. . Aub, J.,C..8 Fairhal 1, L.T., Minot, A.S., and Reznikoff, P. Lead poisoning, medicine monographs. Baltimore: The Williams & Wilkins Co.., 7:1926. Bacon, A.'P.C. Froome, K., Sent, A., Cooke, T., and Sowerby, P. Lead poisoning from drinking soft water. 'Lancet 1:264, 1967. Barry, P.S.I., and Mossman, D-B, Lead concentrations in human tissues, Br. J. InduStr. Med. 27:339,1970, Beattie, A.D., Oagg, J.H., Goldberg, A., Wang, I.,and Ronald, J. Lead poisoning in rural Scotland. B,r, Med, J, 2:488,1972 a, Beattie, A.D., Moore, M.R., Devenay, W.T., Miller, A,R., and Goldberg, A. Environmental lead pollution in an urban soft-water area. Br. Med, <J. 2:491,1972 b, Berlin, A., Pel Castilho, P., and Smeets, 0. European intercom parison programmes. Proceedings. International Symposium on the Environmental Health Aspects of Lead, Amsterdam, 1033-1049, Oct, 1972. Berlin, M,, Gage, J..and Jonnson, E. Increased aromatics in motor fuels: A review of the environmental and health aspects. Wprk-environm.-hith 11:1,1974. Berlin, A., Lauwerys, R,, Bucbet, J.P., Roels, H., Pel Castilho, P., and Smeets, J, Inter.comparison programme on the analysis of lead, cadmium and mercury in biological fluids. Interna tional Symposium-Environment and Health CEC-EPA-WHO, Paris, June 1974 a. DUP040007321 In the statistical treatment of my data, I have received valuable help and advice from Mr Timo Partanen, M.Sc., Mr Erkki Jarvinen, M.Sc., Mr Markku Nurminen, M.Sc., Mrs Sisko Asp, M.Sc. and Mrs Pirjo Fahlstrom. For all this, I wish to express my sincere thanks. During the course of the study several persons have earned my deep gratitude for their unselfish assistance; I feel especial ly indebted to Mrs Ritva Vesanto, Mrs Tuulikki Poukka, Raija Berghall, M.D., Frederika Tekonen, M.D., Ove Nasman, M.D. and Miss Rit va Jarnstrom. Similarly, I wish to thank Mrs Marja-Liisa Korkala for her .drpwi ngs.. My very cordial thanks are extended to Professor Nils Riska, M.D., Head of Mjalbolsta Hospital, for his constant encouragement, and the supporting attitude he adopted to my investigation. My warmest gratitude is, however, due to my wife, who throughout took an encouraging interest in my investigation; moreover, her endless understanding and patience greatly facilitated my work during the long course of the study. My gratitude is also extended to Mr Fred A Fewster, who revised the language of the manuscript. This investigation has been supported financially by the Finska Lakaresa11skapet. Helsinki, April 1975 Claes Henrik Nordman DUP040007322 102 CEC: Commission of the European Communities. Air lead concentrations in the European community. Yearly report: April 1971March 1972. Office for Official Publications of the European Communities, Luxembourg, Sept. 1972. Chisolm, J.J. Lead poisoning. Sci Am. 224:15,1971 Chisolm, J.J., and MelTits, ,p> ' Interrelationships among blood lead concentration, quantitative daily ala-e output and the response to calcium edta. The Third Meeting of the Subcommittee on the toxicology of Metals, Tokyo 18-23,11.1974. 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