Document ppVaNNrDk3oerLQponLBzjbw

KOMMISSION OER e u r o p Ais c h e n GEMEINSCHAFTEN COMMISSION OES c o mmu n a u t e s e u r o p Ee n n e s UNITED STATES ENVIRONMENTAL PROTECTION AGENCY INTERNATIONAL SYMPOSIUM Environmental health aspects of lead Die gesundheitllclien Aspekte der Umweltverschmutzung durch Blei Les probiemes sanitaires poses par le plomb present dans I'environnement LEAD UPTAKE PROW POOD TOLAN a . AND KI/TON G. Ministry of Apiculture, Fisheries and Food LOSnXMt ENGLAND Amsterdam, October Z - 6, 1972 N40692 suwaar Tha food components of tha national diat halt boon axtansiYaly monitored for load* Analyses of food aaaploa representative of the average diet indieatod a naan load concentration in the diat of 0.13 mg/kg fron which it Was astlnatad that tha daily intaka of tba average parson in tha United Kingdom anountad to about 200 aierogrannoa of load* It was olaar that there was no food or food eatagory which was a major source of load* Mora land was prasant in canned food than in tha corrasponding frash food although this was of minor signlfiesaee in tha diat* DUP050057835 Introduction Lead has been a ubiquitous contaminant of food for centuries. In tbo United XiagiM, regulation* exist to limit the amount of lead whlah say be present in food, and by the gradual control of potential oontaainators such as lead based pesticides, lead treated equipment, lead containing food colourings etc, the lead eontenta of many foods hare been reduced. Under the present regulations, a general Unit of 2,0 agAg, on a vet weight basis* is applied to npst foods, for a few, a higher Unit is allowed and in Sons special cases, such as soft drinks, a lower Unit is required (1). The present concern about the effects of traces of heavy netals in the environment has rekindled interest in lead oontanination of food. For the Majority of people, the diet represents the only source of exposure to nost heavy netals; lead is the obvious exception in that water and the atnosphere nay represent other major sources. It is therefore important that the contribution by food to the total intake of lead is accurately known in order to sake a neaningful assessment of the hazards of the different sources of lead to nan. Although there is such published information on the lead content of food, much of this was obtained before the recent improvements in snslytioal techniques end increase in accuracy and sensitivity of lead determination. There are also new environmental interests such as the Offset of load contamination of food crops by industrial lead deposition, lead fallout from vehicle emissions, load in sewage sludge used on agricultural land and lead discharges into water, and for these there is little detailed information. The Ministry of Agriculture, Fisheries and Food in this country has therefore carried out a detailed survey of the lead eontent of food. The *ies of this survey were:- (a) to assess the intake of lead from food by the average consumer; (b) to assess the contents of load in major foods of the national diet; (c) to determine whether any <3ass of food might present special features with respect to lead content, including reassessment of some foods for whleh special previsions exist in the Lead in Food Regulations; (d) to make special checks on the lead content of foods in soma areas that night be affected by local contamination of the environment. A summary report on the results obtained so far in this survey has been published (2) and tibia paper deals in greater detail with the first two Objectives; only a United aaount of data has been obtained in relation to the last two objectives, investigations arc still in progress* 1 Description of tto flamt The survey wae eesentially a collaborative exercise with various speciali*t laboratories undertaking particular Motions of tbs analytical work. Tints fisheries Laboratories of this Ministry and the Department of Agriculture and fisheries for Sootland exasined fish and Shsllfish, ths Plant Pathology Laboratory of this Ministry exasined fndt and vegetables, and ths Governsent Chemist looked at othsr foods. Load was determined at all laboratories by atomic absorption epectro-- photoaetry but extraction procedures varied, and a loser Unit of determination was attained at sons laboratories. The sethod of ex traction was either by wet oxidation of the sample using a Mixture of sulphuric and nitric acids or by dry-ashing. Improvement in recovery Wes achieved by dbntika&ng with ammonium pyrrolidine dithfe carbamate and extracting the complex with 4-aethyl pentan-2-one for the final deterainatlott. for the results reported here, the lowest level of deter mination was 0*01 ngAg. The daily intake of lead frea food by the average individual was estimated from ths results of analysea of "market haaket" saaples, oalled for convenience the Total Diet Study (3)* This was originally designed to s s mb s the amount of pesticide residues in the diet and ia presently being analysed for lead, mercury and cadmium. In ths study, cooperation is sought from domestic science colleges through out ths country who purchase, prepare and oook the food where appropriate, and blend together samples of food representative of the diet in the area Of the college. The proportions Of different foods in the sample are based on National Expenditure Estimates and The national food Survey. The foods are grouped into eight analytically compatible subgroups before blending and analysis; these groups are cereals, meat and fish, fish, fats and oils, fruits and preserves, root vegetables, green vegetables, and milk. Bach of the eight groups contain each food in that category in the correct proportion for each region and saason, in the edible form. The samples are obtained at quarterly intervals so that each college produces 4 seta of samples which are analysed at a central laboratory. In the oaae of lead, extra precautions are re quired since lead may he transferred to the food during preparation* and cobbing from water used for cooking or lead in the equipment used. A sasple of the water ia therefore analysed and Shacks are mads on ths equipment if ths results indioats that this is necessary. A wide variety of individual foods wars also examined for lead contents. Besuits Ths results of ths Total Diet Study are summarised in Table 1. The seen lead content of the diet is estimated to be in the region of 0.13 agAg of diet and therefore it is estimated that a person eonsuming 1.5 kg of a normal diet each day would take in about 200 miorogrammes of load from the food. Furthermore it has been estimated that ths daily 2 DUP050057837 intake of lead in the United Kingdom from beverages is about 20 microgrammes (4) making a total intake iron food and beverages of about 220 micrpgraanes* Sosa small differences in load content between the food groups ware observed* Vegetables were found to contain the most lead with cereals and meats not very far behind, these groups averaging in the region of 0*2 mg/kg. These categories oonstitnte about 50# by weight of the food in the diet as a whole mod it is estimated that they contribute some 79# of the dietary lead* Fruits contained about 0*1 mg/kg but because they represent a fairly large component of the diet, their relative contribution of lead is similar to that of the above groups. Fats com a minor dietary component and oontribute little lead* Unlike mercury, the amount of lead in fish appears to be less than in other foods and because of the relatively low consumption of fish in this country, the amount of lead in the diet from this source is negligible, in the region of 3$ of dietary lead. Milk contained the least amount and many of the samples examined contained lass than 0.01 mg/kg* Although a figure of 0.03 ag/kg is quoted it is likely that the real value is very such lower* Results from other laboratories have indicated that the value is possibly in the region of 0.002 - 0.003 mg/kg. The detailed results for the individual foods are not given in thin paper. They have been presented elsewhere (2). It is sufficient to say that the results for the lead oontents of the staple foods were in good agreement with the results of the Total Piet Study* However, some aspects of this part of the survey merit further attention in particular the amount of lead in canned food. The amounts of lead in some canned foods are compared in Table 2 with the amounts present in the corresponding foods when not contained in cans. It is dear that for a wide variety of foods, the lead value in enhanced by canning* For baby foods, carrots, peas and pears, there is approximately 0.2 mg more lead par kg when canned than when fresh* This difference is very much larger, of the order of 1*0 mg/kg, in the ease of corn and spinach, hut these latter results were based on a vary limited number of samples. As expected, canned corned beef also contained more lead than fresh beef* Milk Was the only item which appeared to be unaffeoted* The levels of lead in cream both in cans and jars were similar and canned evaporated milk contained a low level of lead* Further work is in progress. QiBeuajriLon The only other figure for comparison of the daily intake of lead from food by the average consumer in this country, is that reported in 19*9(5). The figure quoted then was between 200 and 230 microgranmes for the average adult which is ` comparable to the figure obtained in the present survey* In the United States, the average daily intake was reported in 1964 to be 120 - 130 mierogramne* per day (6). and in 1965 to be about *<00 miorograamee per dwr(7), and in i960 to be in the region of 330 microgrammes per day/o/These figures agree fairly 3 well with one another and therefore are probably reliable estimates but are somewhat higher than the figures obtained for the United Kingdom. This any not necessarily reflect a real difference and the difference aay&e in the methods of estimating lead intake from food* Thus the U S figures are estimated for an adult man based on an average daily food consumption of 2*0 kg as opposed to 1*? kg used for the U K estimate which is the average daily food consumption for the population as a whole based on figures taken from the National food Survey* Similarly the U K figure is representative of the average diet of the population and therefore the much larger milk consumption by children than by adults will have a large influence on the size of the milk component in the average diet* The U 6 figures are representative of adult diets which contain much less milk* It. should be pointed out that the daily intake of 200 mierogrammee from food is probably a alight overestimate. Besulte of loss than 0*01 mgAgi tha limit of determination, for individual samples have been taken to equal 0.01 mg/kg in estimating the overall means is - making the worst assumption. If values of less than 0.01 mg/kg are assumed to equal zero, a lower estimate by some 10 micrograins is obtained. Also if it is assumed that milk contributes a negligible amount of load, tha daily intake may well be in the region of 170 - l80 ndorogrammes. It is not dear how much dietary lead is of natural origin and how much results from the use of lead by man* It has bom reported that foods grown in areas remote from urban, industrial or mining activities all contained traces of load (9) and the natural lead content of food has bean estimated to be 0*01 mg/kg wet weight ( 7 ). On this basis, a person consuming 1*5 kg of food would be expected bo have a dietary intake of 15 aderogranmiee per dmrof load from natural sources which would moan that over 90# of the lead in food arose from other sources* To take the argument one step further, if, as it appears, all the major food groups contribute roughly similar amounts of lead to the diet and no group appears to be an excessive or persistent source of dietary lead, then the major proportion of load in the most foods is not immediately of natural origin. It is far from clear at the present time what these sources are and how they effect food* Alternatively, the natural content of load- in food may bo higher; this may be the ease in the United Kingdom whore base rooks have boon reported to be richer in load than in some other countries. Although major improvements in canning technology over the years have produced considerable reductions in the load contents of canned foods, it is apparent that rssidual amounts of lead ovsr and above that ordinarily present in food may still occur in canned foods. From the results of this survey, this residue may bo of the order of 0*1 - 0.2 mg/kg. Aocording to the Motional Food Survey (ID), the consumption of canned foods by tha average person amounts to about 100 grams par day. It is therefore estimated that canned foods contribute some 10 - 20 nderojgrammes of load to the average diet or some 5 * 10# of the total load* For babies, however, the proportion may be considerably greater since canned baby food nay form the major item of the diet of some babies* 4 The average lead oontent of canned baby food was found to be 0*24 ag/kg. A saw regulation has been proposed which will lower the Halt for the amount of lead permitted in baby foods and step* hare already been taken by manufacturers in the United Kingdom to lower the lead level by modifications to Idle canning processes* 5 DUP050057840 Referencea Cited 1. Ministry of Agriculture, Fisheries sod Food (1961). The load in Food Regulations. SI 1961 No 1931. HMSO. 2, Ministry of Agriculture, Fisheries and Food (1971). Second Report of tbs Working Party on the Monitoring of Food stuffs for Heavy Metals. Survey of Lead in Food. HMSO. 3. Harries, J M, Jones, C M fc J O'Q Tatton. (1969) Pesticide residues in the Total Diet in England and Wales, 1966 1967. 1. Organisation of a Total Piet Study. J Sei Fd Agrlc 20, 242 * 243. 4. Annual Report of the Chief Medical Officer of the Ministry of Health (1967). On the State of the Public Health. Lead in the Environment. 127 ** 132. HMSO. 5. Monier-ViHiams, G W (1949). Trace Elements in Food. London, Chapman fc Ball* 6. Kehoe, R A (1964). Normal Metabolism of Lead. Arch Environ Hlth. 8, 232 - 235. 7. Patterson, C C (1969). Contaminated and natural lead environments of nan* Arch Environ Hlth, 11, 344 36$. 8. Schroeder, H A It I E Tipton (1968). The Human Body Burden of Lead. Arch Environ Hlth. lg, 965. 9. Kehoe, R A, Thamann, F & J Cholak (1933). Normal absorption and excretion of lead. X. Lead absorption and excretion in primitive life. J Ind flyg. lg, 257 - 272. 10. Ministry of Agriculture, Fisheries and Food (1971). Annual Report of the National Food Survey Committee. Household Food Consumption and Expenditure: 1969. HMSO. TABLE 1 Lead contents and consumption estimates of the lain food categories of the national diet la the United Kingdom Food Category Mean lead concentration mgAg (wet weight) Estimated weight of food eaten kg per day Estimated lead intake microgrammes per day Cereals Meat and fish (Fish) Fata Fruits and preserves Root vegetables Green vegetables Milk 0.17 0,17 (0.08) 0.08 0.12 0.20 0.24 0.03 0,27 0,18 (0.02) 0.08 0.25 o.a 0.11 0.40 46 31 (2) 6 30 42 . 26 12 Tbtal 0,13 (weighted mean) 1.5 about 200 Note The sean lead content of the diet as a whole is weighted according to the relative proportions of the different food groups consumed. DUP050057842 A comparison of the lead content of soap food %diaa canned and not in cans Food Baby food* Carrots Peas Corn Spinach Beef Creaa Milk Peers Cherries Mean lead concentration (mg/kg vet weight) Not ixi cana Ctauitd 0.04 (in jars) 0.02 0.02 o.ca 0.02 0.23 0.12 (in jars) 0,03 0.10 0.05 (in jars) 0.24 0.22 0.21 1,22 0.95 1.2 (corned beef) 0.10 0,05 (evaporated ailk) 0.29 0,17 i DUP050057843