Document Qg6nDXzdY35nZde4Z2GKgkNDk

Ijit.Arch.Occ'up.Hlth 35,1-18 (1975) by Springer-Verlag 1975 Dose-Response Relationships for Inorganic Lead L Biochemical and Haematological Responses R. L. ZIELHUIS Coronei Laboratory, Faculty of Medicine, University of Amsterdam, Amsterdam Received January 20, 1975 / Accepted February 5, 1975 "\ Summary. The author reviewed literature data On the relationship between lead in blood levels (PbB) and various biochemical and haematological responses. PbB levels may be regarded as representative for internal dose. The percentage of subjects with a specified intensity of a speci fied response in groups of subjects has been calculated in relation to PbB, This Pose-Response (P-R) relationship portrays the increase of bio logical effects with increasing internal dose, qualitatively and quanti tatively, and can be used to evaluate the health significance of Pb ex posure in occupational and public health. D-R-curves have been calculated for fi-aminolaevulinic acid dehydratase activity in erythrocytes (ALAD), 5-aminoiaevulinie acid excretion in urine (ALAU), protoporphyrin in erythrocytes (PPE), Na+-K+-ATPase activity in erythrocytes and reduced ' glutathion content of erythrocytes. Various other biochemical and haema tological responses are discussed in regard to their relationship with PbB. In a subsequent paper the prevalence of functional effects in re lation to PbB will be discussed. Key words; Lead - Biologic Response - Lead in Blood - ALAD in Brythrocytes - ALA in Urine - Protoporphyrin in Erythrocytes. INTRODUCTION The objective of part I and part II of this study is to evalu ate the relationship between lead in blood (PbB) levels and subclinical biochemical and haematological (I) and subclinical functional (II) responses; if possible dose-response (D-R) re lationships are calculated from literature data, published in recent years. The range of PbB = 0-70 vg/100 ml blood is covered. The resulting data on D-R-relationships and on no response levels will be discussed in view of the significance for occupational and public health. 1 TEH 0470344 DOSE Inorganic lead (Pb)- exposure occurs through, inhalation and ingestion. In occupational exposure respiratory uptake may largely exceed oral uptake; control of Pb concentration in air and of duration of exposure generally speaking achieves prevention of Pb poisoning. However, in exposure of the general public the relative contribution of oral uptake usually exceeds that of respiratory uptake. The effective total exposure, i.e. amounts of Pb taken up by tlie body per unit of time over a stated period of time, is very difficult to measure quantitatively, particularly in the sphere of public health. .This effective exposure yields an internal load; because Pb.has a long biological half life (t y), a body burden is built up. The total body burden can be roughly divided into (Pietrovsky, 1970): 1. rapid exchange pool in blood and soft tissues; 2. intermediate exchange pool in skin, muscles; 3. exchange pool in bone: a) intermediate exchange in bone marrow, trabeculae, b) slow exchange in dense bone, teeth. The total body burden therefore is composed out of various partial body burdens, in Which the rapid exchange pool, must prob ably reflects the biologically effective body burden, indicated by lead in blood, making up about 2% of total lead burden (Baloh, 1974). Approximately 9.0% of blood lead is bound to erythro cytes; plasma lead (0.2% of total burden) is made up of two fractions: plasma protein bound fraction and diffusable frae- * tiOn, the latter being the metabolically active center of the body burden. In a more or less steady state there is a dynamic equilibrium between various compartments; the rate constants k (indicating the rapidity with which an equilibrium can be reached between two compartments) for different means of in ternal exchange between various compartments with the diffus able plasma lead probably decrease in the following orders kplasmapro'tein Pb, k-erythrocyte bound Pb, k-soft tissue Pb, k-hard tissue (Baloh, 1974), The diffusable plasma Pb probably offers the best approxi mation of (die biologically effective Pb burden; however, it is very difficult to measure in practice. The red blood cell/ plasma partition of lead may be the important decisive factor for the development of toxic manifestations; the plasma frac tion probably is not a constant fraction of total blood lead concentration, and as such cannot be predicted from it in an individual (Waldron, 1974); however for groups of subjects PbB will probably offer a reasonable indication of it. Particularly in case of a steady state exposure there also exists a relationship between effective total external ex posure and biologically effective Pb burden: \the external dose 2 h. . ) TEH 0470345 DUP050083163 results in an aequivalent internal "dose". In evaluating D-Rrelationships lead in blood levels (PbB) represent the internal dose and consequently also the effective external dose. lead in blood level undouptedly is the parameter used in most studies up till now available. Moreover sampling is not too inconvenient in practice. Not only because of the avail ability of literature data, but also because of theoretical reasons PbB as measure of dose is to be preferred above other possible parameters of internal exposure, such as Eb in urine, in hair, in teeth. EDTA-provocated Pb excretion in urine may provide a more direct measurement of the rapid exchange pool; however in public health practice, it has serious drawbacks: application of EDTA; preferably 24 hr specimen of urine; possibility of contaminations; this makes it difficult to use this method in epidemiological studies. It should be stressed that measurement of PbB-levels en counters many pitfalls. Even in the most competent labora-. toties, on multiple runs of the same blood sample, there is a 15% error in the measured value (Baloh, 1974). Two recent intercomparison programmes on PbB analyses within the Europ, Econ. Comm, provided evidence of the often poor comparability of data (Berlin et al., 1974a). In this paper particularly the internal dose as represented by PbB up to 70 \ig/lOO ml total blood in its relationship with biologic responses will be evaluated; the data are relevant for moderate occupational exposure, and cover the most relevant range of public exposure. According to modern notation in analytical , chemistry, it is preferred to .express PbB in ppb's (1 ppb 1 yg/1 = 0,1 ug/100 ml); however because up till now almost all literature data are expressed in pg/100 ml or yg/100 g, this notation is still used in order to avoid confusion. r DOSE-RESPONSE RELATIONSHIPS, INTRODUCTORY REMARKS If in an individual subject the internal dose exceeds the noeffegt level, biological responses occur: the intensity of a specified response may increase, and more types of responses may occur. In a group of subjects the number of persons with biological responses also increases with increasing dose. One distinguishes: dose-effect (D-B) relationship, i.e, the relationship between' dose and intensity (quantity) of a specified parameter of response in an individual ("graded response"); dose-response (d -r ) relationship, i.e. the relationship between dose and relative number (percentage) of individuals with a specified (quantity) intensity of a specified parameter of i t 3 TEH 0470346 DUP050083164 response in a group pf subjects ("quantal response1*). Individual subjects differ in D-E-relationships both in . regard to threshold level (no-effect level) and slope. For a group this interindividual variability manifests itself in the D-R-curve. As will be discussed more fully in part IIt exact no-effect/response levels cannot be determined; one can only derive practical no-effect/response levels; the practical no-response level corresponds to that PbB level which does not induce a specified response in > 5% of subjects. It should be clearly understood that according to the concept given a "no--response level", does not indicate that any response does not exist, but that any specified (quantal) response does not exist. 6-AMINOLAEVULINIC ACID DEHYDRATASE IN ERYTHROCYTES (ALAD) It is wellknown that ALAD is extremely sensitive for Pb; in hibition of ALAD in erythrocytes parallels inhibition in other tissues, e.g. liver (Secchi et al., 1974). A review on the ef fects of Pb on ALAD has been published by Hernberg et al. (1972). There exists a negative relationship,, particularly in the range PbB = 15-70 ug/100 ml. There is suggestive evidence that the ho-effect level is about 10 yg Pb/IOQ ml"(Schaller et al., 1971; Granick et al.., 1973; Hernberg, 1974). Sakurai et al. (1974) plotted means of log ALAD in workers against each 5 yg/100 ml subdivision of PbB for PbB up to 65 yg/100 ml; the regression was not linear. In workers with PbB < 30 yg/100 ml no correlation existed between both parameters. The data suggested an inflection point somewhere around 2530 yg Pb/lOO ml. Moreover in the range of PbB = 0-30 yg/100 ml the ALAD in non-exposed controls was somewhat higher than in exposed workers. Tomokuni (1974) found a different behav iour of ALAD in non-exposed subjects and in exposed workers: the optimum pH for determination of ALAD shifted from 6.8 to 6.0; the reason for this is not yet clear. If one makes use of this different behaviour, the power of ALAD to discrimi nate exposed from non-exposed subjects at low PbB-levels in creases. The intraindividual variability in non-exposed males and females over 3 weeks is small; coefficient of variation 4.56,8% (Stuik, 1974). Recently the Europ. Econ, Comm, has stan dardized the ALAD determination; the interlaboratory compati bility proved to be much better than for PbB (Berlin et al., 1974b), The significance of ALAD inhibition due to Pb in regard to health is still opef./*jor discussion. The present consensus / - A. I%* * TEH 0470347 DUP050083165 Fig.l Percentage of subj ects with more than 40ft and 70* inhibition of MAD with increasing PbB appears aptly stated as follows by NAS (1972) in regard to ALAD for the range of PbB up to 40 ug/100 ml: "its biological significance is dubious, because it is unaccompanied by any detectable effects on the biological function of intact man". Maxfield et al. (1972) demonstrated that dogs fed with Pb acetate (100, 500 or 1000 ppm in diet) were similar to con trols in their haematologiqal functions, although blood ALAD levels were severely (to ^ of preexposure level) depressed by the lead diet. Garber et al, (1973) administered Pb to 3 strains of mice with genetically different ALAD levels in the liver; there was no relationship with ALAD in acute and subacute toxicity studies as far as letality, body weight loss, liver and kidney weight changes or decrease in hemato crit are'concerned. It appears that the toxicological proper ties of lead, at least as far as studied in above mentioned experiments, are not dependent upon the degree of ALAD inhi bition. The D-R-relationship has been calculated from 2 sources: a set of data on male workers, provided by Hernberg (Helsinki), n = 221; a set of data on children, provided by Schaller(Nflrnberg), n= 80. We calculated the percentage of subjects with ALAD < 700 jimol PBG/hr/1 (i.e, lower limit in adults with PbB < 15 ug/ 100 .ml) and with ALAD < 350 nmol PBG/hr/1; this corresponds to about 60 and 30$ of average ALAD for PbB -s 14 ug/100 ml, i.e. 4o% and 70% inhibition. The recently agreed upon European standardised method had not yet been introduced;. however the D-B-relationship will not be altered by using other units. In adults the no-response level of PbB for 40% and 70% inhibition appears to be 15-20 ug Pb/100 ml and 25-30 ug/ TEH 0470348 DUP050083166 100 ml respectively; the data suggest a lower no response level for children, particularly for inhibition > 40%s 5-10 vg/100 ml; for inhibition > 70% thp level appears to be 2025 pg/100 ml. The D-R curves are given in Fig.1. g-AMINOLAEVULINIC ACID EXCRETION IN URINE (ALAU-). Inhibition of ALAO hampers transformation of ALA to porpho- bilinogeen; increase of ALA in serum and in urine results; very few data on ALA in serum exist, many on ALAU. There is evidence that ALAU in children is a less valid parameter of . response than in adults (Specter et al., 1971; Pawel et al., 1971) and that ALAU in females may be higher than in males (Roels et al., 1975), Because ALAU generally does not marked ly increase at PbB < 40 vg/100 ml, it does not provide a good means of biological monitoring in the sphere of public health; "particularly for PbB > 45 vg/100 ml there is a rapid increase in ALAU (Lauwerys et al., 1974; Zielhuis, 1973; Sakurai et al., 1974); however there are indications that in females in creased ALAU already may occur at PbB < 40 ug/100 ml: Roels et al. (1975) found a positive correlation between PbB and ALAU in females and not in males for the range.of PbB * 20- 50 vg/100 ml.' . ALAU as such probably has no direct relevance for health; increased ALA-excretion indicates that porphyrinsynthesis is impaired. McGillion et al* (1973) however observed increased activity in urine after i.p, injection of high-doses of ALA. In occupational health ALAU > lo mg/1 is regarded as a warn ing signal and as indicator of potentially hazardous exposure (Zielhuis, .1969). There is a general consensus that in public health increase of ALAU should be regarded as unacceptable. We calculated the percentage of male workers with ALAU > 5 mg/1 (i.e. upper limit in non occupationally exposed sub jects) and > 10 mg/1 (acceptable limit in workers) from graphs published by Haeger-Aronsen (1971) and Selander et al. (1970); the method of Mauserall-Granick was applied for the majority of samples; a few were analysed according to Grabecki (Table 2). COPROPORPHYRIN EXCRETION IN URINE (CPU) It has often been shown that increase of PbB induces increased CPU; however CPU is less specific for Pb exposure than ALAU, and ALAU appears to be at least as sensitive as CPU. So, there is no advantage of monitoring CPU instead of ALAU; increase of CPU does not add new information in addition to increase of ALAU. 6 ' ' * TEH 0470349 ' -'A DUP050083167 Tablet 1 Percentage of adults and children with more than 4o% and 7o% inhibition of averaged ALAD-activity in controls (PKB -$14 yg/100 ml) PbB Adults (Children n >40% >70% n >40% >70% 14 15-24 25-34 35-44 45-54 55-64 65-74 30 13 26 62 32 97 53 100 37 100 43 100 221 .. 3 12 22 68 92 95 9 37 24 lo " 80 11 73 88 9q - 0 8 13 so - Table 2 , Percentage of male adults with ALAU > 5 mg/1 and > lO mg/1 in relation ship to PbB (yg/100 ml) PbB yg/100 ml n >5 >10 11-20 21-30 31-40 41-50 51-60 61-70 17 27 ' 36 55 38 - 34 O O 14 33 74 88 O 0 3 11 37 50 * 207 in males the no-response level for ALAU > 5 yg/1 is > 30 yg/lOO ml for > lO mg/1 > 40 yg/100 ml. The D-R-curve is given in Fig.2. Fig, 2 Percentage of subjects with ALAU > 5 mg/1 and > lo mg/1 with increas ing PbB 7 TEH 0470350 DUP050083168 PROTOPORPHYRIN IX IN ERYTHROCYTES (PPE) +4 Increased lead burden interferes with utilisation of Fe ; the haem synthesis is impaired. This process primarily takes place in the bpne marrow. It causes increase of PPE in eryth rocytes, 'excess Fe in blood, ultimately anaemia. There is a time lag up to 3 months before increase of PP may become ap parent in peripheral erythrocytes (Sassa et al., 1973). increase of PPE appears to be sensitive and specific for lead exposure. According to Gajdos et al. (1973) a combi nation "of increased ALAU, CPU and PPE without increased ex cretion of uroporphyrin is specific for lead effects; noninhibited ALAU in combination with increased PPE indicates. Fe-deficiency (Sassa et al., 1973); Fe deficiency may also contribute to increase of PPE in asymptomatic Pb absorption. There is one known rare disease, erythropoetic protoporphyria, that produces the markedly elevated PPE levels as seen in acute lead poisoning (Haeger-Aronseb et al., 1966). Accord ing to.Baloh (1974) increase of erythrocyte porphyrins might even replace the blood lead test as the primary screening de vice for increased lead absorption. In contrast to altered levels of ALAU or ALAU an elevated PPE may persist for months, even after .PbB has already, de creased considerably. The increase of PPE with PbB is curvi linear. The increase pf PPE in lead exposure has not received much attention until recent years. Various methods are in use, some of them measuring protoporphyrin in erythrocytes (PPE) ' itself, others measuring free erythrocyte porphyrins (FEP), 90% of which is PP (Baloh, 1974). in a human volunteer study with oral ingestion of Pb acet ate Stuik (1974) observed a difference between adult males and females in their response of PPE: the increase in females occurred at lower PbB (25-35 yg/loo ml against 35-45 ug/100ml in males), and the slope was steeper. This has recently been confirmed for FEP in an epidemiological study in occu pationally exposed males and females (Roels et al.,- 1975) . Sassa et al. (1973) studied FEP levels in children; they came to the following conclusions: in a large group of children (n =.138) with PbB = 20-80 jjg/100 ml the coefficient of correlation between log FEP and PbB , + 0.72;- in a group of these children (n = 26) known to have had constant Pb levels for at least 3 months r = + 0.91. Because methods for measuring PPE and FEP are not standardlse'd, the levels as such reported in literature cannot be. grouped together. The author therefore took as cut off level the PPE/FEP level not exceeded by about 95% of subjects with PbBw <' 20 yg/100 ml. Vi -V t , w 8 TEH 0470351 DUP050083169 Table 3 Percentage of adult male subjects exceeding PEP levels as found in subjects with PbB < 20 yg/lOO ml (data Roels, 1974) PbB n % > "normal" level 11-20 21-30 31-40 41-50 51-60 61-70 . 26 43 32 4 r% 2 vl 109 ' o 7 A 19 -100 Fig.3. Percentage of subjects with increased PEP with increasing PbB in order to calculate the D-R-curve for adult male subjects the author used the following data: FEP levels in 109 subjects (non-exposed and exposed) studied by Roels (University of Louvain, personal communication 1974); 95% of subjects with PbB < 20 yg/100 ml did not ex ceed 80 yg FEP/100 ml ery. The D-R-relationship is given in Table 3 and Fig.3, The D-R-relationship for adult females (non exposed and ex posed) , also based upon the study by Roels et al. (1975), is given in Table 4 and Fig.3. The D-R-relationship for children has been calculated by combining data on FEP given by Schaller (Niirnberg) and Piomelli (Balloh, 1974) (Table 5 and Fig.3) . Sassa et al.'s (1973) data were not used for the calculation, because they did not examine children in the PbB-range 14 yg/100 ml, and because they reported their FEP levels only at PbB 20, 30j 40 etc. yg/lop .ail. TEH 0470352 DUP050083170 V I Table 4 percentage of adult female subjects exceeding FEP levels as found in subjects with PbB < 20 ug/100 ml PbB n % > "normal"' level 11-20 21-30 31-40 41-50 51-60 61-70 28 9 8 >4 JW 49 4 33 90 1 J100 Table 5. Percentage of children exceeding PEP levels in subjects with 20 ug/lOO ml PbB n % > normal level <20 21-30 31-40 41-50 51-60 61-70 87 72 24 i4 n 12 5 36 219 5 21 /I 29 * 64 Comparison of the 3 D-R-curves highly suggests an increased response of PPB (FEP) in adult females in comparison to adult males; however/ the number of data on females is still very limited. The data are also suggestive for increased response in children; earlier response in children is also suggested by recent data from RoeIs et al. (1975), increase of PP in erythrocytes should be regarded as an early biologic response, indicating interference of Pb with haemsynthesis'. The response appears to be more sensitive than increase of AIAU, also in adult male subjects. Presence of Fe-deficiency (in women due to menstrual blood loss, in chil dren due to low socio-economic status and malnutrition?) may be a' wide spread intervening factor, asking for extra caution, it should be granted, this is still a hypothesis, not ad equately studied yet. .v. The no-response level for increase of PPE (FEP) will be about PbB 20-25 vg/100 ml in adult females and children, and 25-30 pg/100 ml in adult males. 5* .* TEH 0470353 DUP050083171 OTHER BIOCHEMICAL PARAMETERS OF RESPONSE In a review paper De Bruin (1971) surveyed many possible bio logical responses as reported in literature, the majority of them observed in animal studies; in case of human exposure PbB levels often were not reported; moreover most human studies have been performed in long term exposed workers, particularly in those with clinical intoxication; they prob ably not always are relevant for the dose range of PbB as discussed in this paper. Increased urinary excretion of hydcoxy-indolacetic acid (HIAA) has been studied in 11 yr old children living in a highly polluted area (Pb in air 31 yg/m3); HIAA was reported to be more sensitive than ALAU (Ghelberg et al., 1966,. 1974). In Workers Urbanowicz et al. (1969) found that increase of ALAU was always accompanied by HIAA; HIAA reached its maximum earlier than ALAU or CPU in relatively highly exposed workers. Stankovic et al. (1974) observed increased excretion of both ALA and HIAA in non-occupationally exposed subjects, living near a lead plant. In above mentioned studies PbB was not measured; PbB > 40 yg/100 ml will probably have been present in many cases. Szadkowski et al. (1973) however reported a decreased HIAA excretion (and not an increase) in policemen with.a slightly increased PbB (20.4 +5.0 yg/lOO ml), without increase of ALAU;. these authors emphasized that analysis of HIAA is very timeconsuming, and up to now not suitable for epidemiological studies. At this moment it is not possible to arrive at a Consensus on the relationship between PbB and HIAA-excretion. Moreover, the meaningfulness in regard to health is not clear; neither is the mechanism of action. In 1973 Cooper et al. reported on blood chemistry in over 300 workers; average duration of exposure 16.3 yrs; in 37% of workers PbB was > 70 yg/100 ml; median PbB = 63 yg/100 ml. ' The following'conclusions were drawn: no.relationship with PbB existed for Ca, P, glucose, cholesterol, total proteins, serum albumin, alk. phosphatase, lactic acid dehydrogenase, urea nitrogen; uric acid had a low positive correlation (r * 0.164); there was an indication of increased bilirubin for PbB > 70 yg/100 ml; transaminase (SGOT) had a low positive correlation (r = 0,175). The slight changes in a few bio chemical parameters in this group (with PbB > 70 yg/100 ml in over a third of subjects) do not indicate health impair ment in subjects with PbB < 70 yg/100 ml; the no-effect levels for these types of changes will probably be above 40 yg/100 ml. Moncrief et al. (1964) reported an Increased pyruvate level after glucose dosage in about 50% of children with PbB = TEH 0470354 DUP050083172 40-60 pg/100 ml; this presents evidence of abnormal citric acid cycle. Not enough data are available to suggest a D-Rrelation; a no-effect-level cannot be given. HEMATOLOGICAL RESPONSES Lead affects blood cells in various ways, sometimes. more or less independent from effects on porphyrinogenesis. Hernberg (1970) presented a review of work by the Finnish group on subtle effects on erythrocytes function. Lead affects the erythrocyte membrane. In exposed workers, some of them with clinical intoxication, Hernberg (1970) described decreased Na+-K+-ATPase activity; no correlation existed with conventional.haematological parameters (e.g. PbB); this lack of correlation was thought to be due to ef fect of Pb on developing cells in bone marrow and not in per ipheral blood. There did not exist conclusive evidence of in creased K+ turnover from the erythrocytes; active transport was unaffected even though activity of Na+-K+-ATPase appar ently was partly inhibited. There existed a wide range of variation in this enzyme activity. Secchi et al (1973) studied this enzyme in critical population groups, hot occu pationally exposed to Pb: in males with PbB = 38 10 yg/ 100 ml (n ?* 10) or with PbB = 36 9.3 yg/lOO ml (n - 22) they found a decreased Na+-K+-ATPase activity if compared with a group with PbB 32 8.2 (n = 26). From the individr ual data of this study (received by personal communication) the author calculated the percentage of subjects with < 40 ymol P/hr/mg tyrosine as indicator of decreased Na+-K+-ATPase activity (Table 6). The D-R-relationship is given in 'Fig.4, In this study by Secchi et al. in critical population groups living in Miland (Italy) PbB levels are high if com pared to levels as reported from other Western-European and American cities. If PbB determination had provided too high values because of faulty techniques, the D-R-curve would even shift to lower PbB levels. The cdefficient of correlation between PbB and Na+-K+-ATPase activity was rather small (r = -0.37); sensitivity and specificity apparently is poor. Up till now this study presents the only Indication that at rathef low levels of PbB (< 30 vg/100 ml) about 50% of sub jects already had a moderate inhibition; the slope of the curve is small; subjects with PbB < 20 yg/100 ml already had an inhibition in 15-20% of cases. One has to await for con firmation in more studies, before the health significance can be evaluated. 12 TEH 0470355 DUP050083173 V. 100 i 0 ' to 30 50 70 pg/tOO ml PbB Fig.4 I Percentage of subjects with inhibited Na+-K+-ATPase with increasing PbB Table 6 Percentage of subjects with inhibited Na+-K+-ATPase activity (<40 ymol P/hr/mg tyrosine) in relationship to PbB (yg/100 ml) PbB n Na+-K+-ATPase < 40 (%) 10-19 20-29 30-39 HP ii 21 33` ' 18 83 17 48 64 72 The Finnish group also studied oxydative degradation s in crease of glucose consumption; the average life span of eryth rocytes decreased from 120 to 101 days in heavily exposed workers with PbB - 59-162 yg/100 ml; the degree of shortening correlated best with that of reticulocytosis, but also with anaemia, CPU, PbB (Hernberg et al., 1967). The no-response level for these parameters probably is > 50 yg/lOO ml (Hernberg, 1974, personal communication). Reels et al. (1974) established a negative correlation be" tween PbB and reduced glutathion (GSH) (r = 0.42; n =* 110). Frpm the individual data of this study (received by personal communication) we calculated the D-R-relationship for GSH < 58 and < 70 mg/100 ml rbc. (Table 7). The D-R-curve is given in Fig.5. This study presents, evidence that at father low PbB levels (< 3Q yg/100 ml) slight reduction of GSH al ready starts to occur; however sensitivity and specificity in regard to PbB apparently appears to be rather poor; the' slope of the curve is slight. The health significance of this not yet confirmed finding is still under discussion. The no V U- TEH 0470356 DUP050083174 Fig.5. Percentage of subjects with decreased GSH with increasing PbB Table 7 Percentage of subjects with GSH < 58 and < 70 mg/loo ml rbc in relationship to PbB (y'g/100 ml) PbB n GSH < 70 GSH < 58 <14 15-24 25-34 35-44 45-54 55-64 65-74 17 32 23 15 1 f 23 r 110 41 63 57 67 I' f 95 J 0 6 13 33 \I J AS response level of PbB for decrease of GSH < 58 yg/100 ml rbc probably is about 25 yg/100 ml. Bead may induce increased osmotic resistance of erythrocytes. According to Quazi (1971) this phenomenon might be used as a simple screening test in children with positive results in 85% of subjects with PbB > 60 yg/100 ml? it was not positive at levels below 40 yg/100 ml. Not enough data are available to suggest a D-R-relationship. Ghelberg et al. (1966) and Barnea et al. (1968) observed increased prevalence of erythrocytes with Helnzbodies in chil dren (PbB was not measured)j the data as given by the authors suggest that exposure may have been rather high, with PbB levels exceeding 35-40 yg/100 ml. No D-R-relationship can be given. it is weilknown that anaemia, i.e. decrease of haemoglobin (Hb) and of number of erythrocytes may occur in exposed subjects before clinical phenomena become manifest. Anaemia probably does not occur at PbB < 40-50 yg/100 ml. Sakurai et al. TEH 0470357 DUP050083175 (1974) did not observe any decrease of Hb and number of erythrocytes in a large group of workers with PbB up to 50 lig/IQO ml. Betts et al. (1973) found a significant nega tive correlation between Hb and PbB'; a decrease already oc curred in 36% of children with PbB - 37-60 yg/100 ml, against 14% in case of PbB < 37 yg/lOO ml. Peuschel et al. (1972) examining 58 children of 1-6 yrs with an increased lead bur den (PbB > 40 yg/100 ml) observed a curvilinear decrease in Hb between PbB 40 and 130 yg/100 ml; however the socio economic condition of this group was very poor* Cooper et al. (1973) studied several haematological para meters in a group of workers, one third of them with a PbB > 70 yg/100 ml; median PbB = 63 yg/100 ml. The following con clusions could be drawn: average Hb did hot decrease up to PbB =* 100 yg/100 ml; red blood cell counts and haematocrites did not correlate with PbB; 14% of workers with PbB > 70 yg/ 100 ml had a low mean corpuscular volume, against 2% in those with PbB < 70 yg/100 ml; microcytosis occurred in 25.9% of subjects in the high PbB group, against 8.6% in the low Pb group; macrocytosis in 6% and 2.7% respectively. Also Kochen et al, (1973) could not find any relation between Ht and PbB. Ghelberg et al, (1974) observed a tendency to macrocytosis in an adult population with increasing exposure; PbB was not measured. Prom this short review on haematological responses the following conclusions may be drawn: little evidence exists that erythrocyte functions are im paired in subjects with PbB < 35-45 yg/lOO ml; haematological parameters do appear to be neither sensi tive nor specific in regard to increase of PbB; the suggested decrease of GSH and of N a+-K+-ATPase ac tivity at low PbB should be confirmed by other studies, be fore the health significance can be evaluated. REFEBBNCES Baloh, R.W.; laboratory diagnosis of increased lead absorption. Arch. environm.Hlth. 28, 198 (1974) "" Barnea, M.s Hematologic alterations in children in an industrial lead polluted zone. Igiena 17, 73 (1968) Berlin, A., Buchet, J.P., del Castilho, P., Lauwerys, B., Boels, H., Smeets, J.: Intercomparison programme on the analysis of Pb, Cd and Hg in biological fluids, Znt.Symp.Recent Advances in the Assessment of Health Effects of Environmental pollution, ECE-EPA-KHO, Paris (1974a) 15 TEH 0470358 DUP050083176 Berlin, A., Schaller, K.H., Sweets, J._: Standardisation of ALAD-determi- nation at the European level.. Int.Symp.Recent Advances in the Assess ment of Health Effects of Environmental Pollution, ECE-EPA-WHO, Paris (1974b) Betts, P.R., Astley, R., Paine, D.N,: Lead intoxication in children in Birmingham. Brit.med.J. 1973 I. 402 de Bruin, A.: Certain biological effects of lead upon the animal organ ism. Arch, environm. Hlth 23, 249 (1971) Cooper, W.C., Tabershaw, I.R., Nelson, K.W.: Laboratory studies of , workers in smelting and refining, in: Environmental health aspects of lead, Int.Symp. Amsterdam 1972, p.571. Luxembourg: Comm.Europ.Conmran. 1973 Gajdos, A., Gajdos-TSrSk, M.: Erreur du diagnostic differentiel entre 1'intoxication par le plomb et la porphyrie intermittente aigue. in: Environmental health aspects of lead, Int.Symp. Amsterdam 1972, p.Sol. Luxembourg: Comm.Europ.Coromun. 1973 Garber, B., Wei, E.: Lead toxicity in mice with genetically different levels of ALAD. Bull, environm."Contam, Toxicol. 213 (1973) Ghelberg, N.W.: Investigations on the appearance of Heinz bodies under the influence of small lead concentrations in the atmosphere. Igiena i5, 209 (1966) Ghelberg, N.W., Bordas, E.: Mean erythrocyte diameter in adults living in an urban atmosphere. Int.Symp.Recent Advances in the Assessment of Health Effects of Environmental Pollution, ECE-EPA-WHO, Paris (1974) Ghelberg, N.W., Gorgan, I., Cherice, I.: BIAA excretion in a population chronically exposed to slight atmospheric lead content. Igiena 15, 87 (1966) Ghelberg, N.W., Tomus, R., Nagy, S., Piersica, V.: The effects of lead in the urban atmosphere on urinary excretion of HIAA in children. Int. Symp. Recent Advances in the Assessment of Health Effects of Environ mental Pollution, ECE-EPA-WHO, Paris (1974) Graniek, J.L., Sassa, S., Graniek, S., Levere, R.D., Kappas, A.: Studies in lead posoning II. Bipchem.Med. B, 149 (1973) Haeger-Aronsen, B.: An assessment of the laboratorytests used to monitor the exposure of lead workers. Brit.J.industr.Med. 28, 52 (1971) Haeger-Aronsen, B., Krook, G.: Erythropoetic protoporphyrinuria. Acta Med.Scand, suppl. 445, 48 (1966) Hernberg, S.: Effect of lead on some erythrocyte functions. Congr.Chem. Pollution and Human Ecology, Prague (1970) Hernberg, S.; Personal communication (1974) Hernberg, Si, Nikkanen, J.: Effect of lead on ALAD. Prapov.Lek. 24, no.2/3, 77 (1972) Hernberg, S.., Nurminen, M., Hasan, J.: Non random shortening of red cell survival times in men exp'osed to lead. Environm.Res. 1_, 247 (1967) Kochen, I.A., Greener, Y.: Levels of lead in bipod and haematocrit. Pediat.Res. 7, 937 (1973) A "- V nV TEH 0470359 DUP050083177 Lauwerys, R., Buchet, j.P.,, Reels, H.A., Materne, D.: Relationship between ALAU and ALAD by lead* Submitted for publication (1974) Maxfield, M.E., Stopps, G.J., Barnes, J.R., Snee, R.D., Agar, A.: Effect of lead on blood regeneration following acute hemorrhage in dogs. Amer.industr.Hyg.Ass,J. 33, 326 (1972) McGillian, F.B,, Moore, M.R., Goldberg, A.: The effect of fi-ALA on the spontaneous activity of mice. Scot.med.J. 18, 133 (1973) Moncrief, A.A., Kpumides, O.P., Clayton, B.E., Patrick, A.D., Renwick, A.G.C., Roberts, G.E.: bead poisoning in children. Arch.Dis.Childh. 39, 1 (1964) MAS.: Comm* on biological effects of atmospheric pollutants, bead; air borne lead in its perspective. Washington: Nat.Acad.Science 1972 pawel, M.A., Frantz, C.N., Pisetsky, i.B.s Screening for lead poisoning with the urinary ALA test. Health Rep. 86, 1030 (1971) Peuschel," S.M. , Kopito, L., SchwachmAnn, H.: Children with an increased lead burden. J.Amer.med.Ass. 222, 462 (1972) Pietrovsky, J.K.: Kinetic behaviour of lead, Congr.Chem.Pollution and Human Ecology, Prague (1970) Quazi, B.: A simple rapid test for lead poisoning. J.Pediat. 79, 80S (1971) Roels, H.A,, Buchet, j.P., Lauwerys, R.R., Sonnet, j.: Comparison of an in vivo effect of inorganic lead and cadmium on gluthione reductase system and ALAD in human erythrocytes. In press (1974). Boels, H.A., lauwerys, R.R., Buchet, j.P., Vrelust, M.-Th.: Response of free erythrocyte porphyrin and urinary fi-aminolevulinic acid in men and women moderately exposed to lead. Int.Arch.Arheitsmed. 34, 97-108 (1975) Sakurai, H., Tugita, M., Tsuchija, K.: Biological response and subjective symptoms in low level lead exposure. Arch.environm.Hlth. 29, 157 (19745 Sassa, S., Granick, J.L., Granick, S., Kappas, A., Levere, R.D.: Studies in lead poisoning I. Biochem.Med. 8, 135 (1973) Schaller, K.H., Mache, K., Haas, Th.Mache, W., Valentin, H. : Die Me thoden'zur Messung der AktivitSt des MAD in Blut. EC Meeting, Erlan gen (1971) ++ Secchi, G.C., Alessio, L., Cambiogghi, G.: Na /K -ATPase activity of erythrocyte membranes. Arch.environm.Hlth. 27, 399 (1973) Secchi, G.C., Erba, L., Cambiaghi, G,: AIAD activity of erythrocytes and liver tissue.in man. Arch.environm.Hlth, 28, 131 (1974) Selander, S., Crame.r, K.: Interrelationships between lead in blood, lead in urine and ALA in urine during lead work. Brit,J.industr.Med. 27, 20 (1970) Specter, M.J,, Guinee, V.F., Davidow, B.: The unsuitability of random urinary ALA samples as a screening test for lead poisoning. J.Pediat. 79, 799 (1971) Stankovifc, b ., KoriCanac, Z., Stankovife, M., Milovanovic, Lj,, Dugandrio, M,: The levels of Hlft^ in the urine of population exposed to lead. Int.Symp.Recent Advances in the Assessment of Health Effects of Environmental Pollution, ECE-EPA-WHO, Paris (1974) 17 TEH 0470360 DUP050083178 Stuik, E.J.: Biological response of male and female volunteers to in organic lead. Int.Arch.Arbeitsmed. 33, 83 (1974) Szadkowski, D., Lehnert, G.s Zur gesundheitlichen Relevant der BleiEmission mit Autoabgasen. In: Environmental health aspects of lead, Int.Symp.Amsterdam 1972, p.781. Luxembourg: Comm.Europ.Commun. 1973 Tola, S., Hernberg, S., Asp, S, Nikkanen, J.: Parameters indicative of absorption and biological effect in new lead exposure, Brit.J. Industr.Med. 30, 134 (1973) Tomokuni, K.6-Aminolaevulinic acid dehydratase test for lead exposure. Arch.environm.Blth. 29, 274 (1974) Urbanowicz, B., Grabecki, J., Kozielska, J.: The urinary excretion of BIAA in industrial lead exposure. Med.d.Lavoro 60, 582 (1969) Ualdron, H.A.: The blood lead threshold. Arch.environm.Bith. 29, 271' (1974) Zielhuis, R.L.: Permissible limits for inorganic lead in industry. In: Proc. 16th Int.Congr.Occup.Hlth., Tokyo 1969, p.5lO. Tokyo: Japan Industrial Safety Ass. 1971 Zielhuis, R.L.: Lead absorption and public health: an appraisal of hazards. In: Environmental health aspects Of lead. Int.Symp.Amsterdam 1972, p.631. Luxembourg: Comm.Europ.Commun. 1973 Prof. Dr. R.L. Zielhuis Coronel Laboratory Faculty of Medicine University of Amsterdam 1. Constantljn Huygensstraat 20 Amsterdam, The Netherlands ,. ., 18 TEH 0470361 y%\ \ DUP050083179