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Trends in the levels of some chlorinated hydrocarbon residues in adipose tissue of Canadians
Encironmental Pollution 65 (1990) 269-278
Trends in the Levels of Some Chlorinated Hydrocarbon Residues in Adipose Tissue of Canadians Jos M e s Food Research Division, Bureau of Chemical Safety, Food Directorate, Health Protection Branch, Health and Welfare Canada, Ottawa, Canada KIA OL2
(Received I I October 1989; accepted 2 February 1990) A BSTRA C T Trends in the levels of hexachloroben=ene, hexachloroo'clohexanes. oxychlordane, t-nonachlor, heptachlor epoxide, dieldrin. DDTs and polychlorinated biphenyls in adipose tissue of the Canadian population were followed from 1969 to 1985. Residues of lindane, dieldrin and p,p'-DDT continuously and significantly (P <0.025) decreased during that time, coincMing with restrictions on their use. Other residues also decreased significantly between 1969 and 1985, although not always continuously, while t-nonachlor levels did not change significantly since 1972. In general no consistent and/or significant differences were obserw.d between the sexes, but in some instances differences were found for a particular residue in a given year. Three arbitrarily chosen age groups (0-25; 26-50 and > 51 years) showed a downward trend in residue levels with time. The resuhs of the surveys also indicate an increase in adipose tissue burden of chlorinated hydrocarbons with age. but this increase became apparently less significant with increasing age.
INTRODUCTION Ever since the determination of D D T residues in human fat by Howell (1948), many different attempts have been made to study not only DDT, but also many other chlorinated hydrocarbons in human adipose tissue as an i n d i c a t i o n of non-occupational exposure. Some investigators restricted their studies to selected compounds, a given sex or a specific population. For 269 EnL'iron. Pollut. 0269-7491/90/$03-50 ©
Printcd in Great Britain
1990 Elsevier Science Publishers Ltd. England.
.los Mes
270
example Yobs (1972) determined polychlorinated biphenyls (PCBs) and Biros & Enos (1973) determined oxychlordane (OCl) in the general population of the USA, while Siddiqui et al. (1981) and Mod et al. (1983) restricted their investigations of organochlorine pesticides to Indian males and one of the Japanese prefectures, respectively. Other researchers studied chlorinated hydrocarbon residues in human populations at regular intervals in order to establish trends in the adipose tissue burden of these residues. Abbott et al. (1985), for example, followed the trends of several chlorinated hydrocarbon residues in the population of the United Kingdom from 1963 to 1983, while Holt et al. 0986) studied several residues in a north-east Louisiana population from 1977 to 1984. Similarly van Dyk et al. (1987) followed the exposure of specific South African subpopulations to organochlorine pesticides from 1973 to 1982. In Canada, nation-wide surveys of chlorinated hydrocarbon residues were carried out in 1969 (Ritcey et al., 1973), 1972 (Mes et ai., 1977), 1976 (Mes et al., 1982) and 1985 (Mes el al., submitted). The results of these surveys are presented in this paper as a function of time, and the effects of such parameters as age and sex are explored.
MATERIALS AND METHODS The collection of abdominal fat samples during the 1969, 1972 and 1976 surveys was restricted to accident victims. During the 1985 monitoring program this restriction was lifted however, after Mes et al. (1985) reported no significant differences in residue levels from victims of accidental and non-accidental death. Although sampling details have been described earlier (Ritcey et al., 1973; Mes et al., 1977, 1982), some pertinent information is TABLE I Sampling Information
Year of sample eolh'ction
1969 1972 1976 1985
Number of samples Males
159 I11 53 81
Females
59 57 45 27
• NA ffi not available. b No age given in 4 samples.
Age groups (years) 0-25
26-50
> 51
41 49 33 28
76 65 41 41
97 54 24 39
Total
Age range ()'ears)
Mean % flit
218 b 168 98 108
ff5-89 9-88 16-97 3-85
NA" 81 NA 90
Chlorinated hydrocarbon residues in adipose tissue
271
summarized in Table 1. Adipose tissue samples were obtained from across Canada and every effort was made to collect them from as many different locations as possible. Nevertheless most samples came from large urban centers. This did not mean, however, that rural samples were excluded, since autopsies of accidental deaths in rural areas are performed mainly in larger cities. Unfortunately, in 1985 no specimens were available from the provinces of Manitoba and Saskatchewan. Although modifications to the analytical methodology were made over the years, the essential steps remained the same and are briefly outlined as follows. Fat samples were extracted with benzene: acetone (1 : 19, v/v) and the lipids removed by low temperature precipitation during the 1969, 1972 and 1976 surveys and by Florisil ® column chromatography during the 1985 survey. In addition, Florisil was used in all surveys to separate PCBs as much as possible from other chlorinated hydrocarbon residues. PCBs were partially separated on a packed gas chromatographic (GC) column, using 6% OV-210 + 4% SE-30 as stationary phase or one of similar polarity. Other chlorinated hydrocarbons were also separated and identified on the same stationary phase, except for the/~ and 7 hexachlorocyclohexane (HCH) isomers, for which a 5% OV-210 column was used. Only during the 1985 survey were c o m p o u n d s other than PCBs separated and identified on a 30 m x 0.24 mm (i.d.) capillary column with DB-5 (J & W Scientific) as the bonded phase, in all surveys the PCBs were quantitated by summation of all peaks after p,p'-DDE in the sample chromatogram, corresponding to similar ones in the Aroclor 1260 standard. In the 1969 and 1972 surveys, residues were confirmed by thin layer chromatography, while during the last two surveys a combination of GC and mass spectrometry (MS) was used. The data were statistically evaluated using the Student's t-test. RESULTS The 1976 and 1985 surveys indicated a skewed distribution of residue levels, which may also be the case in the earlier surveys, but could not be verified since the individual data are no longer available. Therefore, the results of these earlier surveys (1969 and 1972) could not be expressed as geometric means or medians. Consequently, only arithmetic means were used to illustrate temporal trends. This approach excluded, however, the use of any substantial statistical trend analysis and only the rather 'crude' Student's ttest was used. The histograms in Fig. l represent the arithmetic means of residue levels in adipose tissue of Canadians between 1969 and 1985. Statistically significant differences (P < 0-025) were observed for all residues Floridin Co.
272
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O,~Oo O,IS-
t,i
r'l ,ooo
.
lOT2 ~JleTg • lg88
L
p'cmo ~
p~Oo¢
Fig. I. Trends in body burden of some chlorinated hydrocarbons in adipose tissue of Canadians from 1969 to 1985.
between the years 1972 and 1985, except for/-nonachlor (t-NCI). Three of the reported residues, namely 7 HCH, dieldrin (HEOD) and p,p'-DDT decreased continuously and significantly from 1969 to 1985. Although residue levels ofp,p'-DDE also continuously decreased over that period of time, the decrease between 1972 and 1976 was not statistically significant. Heptachlor epoxide (HpEp) levels remained essentially the same between 1969 and 1976, but were significantly lower in 1985. A noticeable increase in /~ HCH residue levels occurred in 1976, for which no ready explanation is available. Figure 2 illustrates trends in residue levels of males and females between 1969 and 1985. Only residues of dieldrin and p,p'-DDT decreased steadily
273
Chlorinated hydrocarbon residues in adipose tissue MALE 1"7 11410 I~1 10F1
•
,o.s
.
-1.0
ioo 0.10 -
--~
FEMALE
¢m
[] ~vo 0.11-
•
Hell
"HC:H
OCl
.~o
,OILS
I-NCl
HpEI)
HIOD o.p**OOT
PGIIo p.Fl-OOl[ p,;C..OOT
Fig. 2. Trendsin body burden of somechlorinated hydrocarbons in body fat of Canadian males and females from 1969 to 1985. and significantly (P < 0-025) from 1969 to 1985 in both males and females. The high level o f Z H C H in males was due to the fl H C H component of these residues. The apparent decrease of PCB levels in males was only significant
between 1976 and 1985. The p,p'-DDE residue level in males decreased significantly until 1976, while the female adipose tissue burden of this residue did not significantly change from 1972 to 1985. No significant changes in residue levels were observed for hexachlorobenzene (HCB), heptachlor epoxide and o,p'-DDT in both sexes between 1972 and 1976. In addition, levels of PCBs and oxychlordane (OCI) in adipose tissue of males did not change significantly over the same period of time. Few differences in residue levels between males and females were statistically significant within a given survey. The p,p'-DDE and dieldrin levels were significantly different between the sexes in 1969 and 1972 only,
274
Jos Mes
0.04,
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I~.
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0.011-
,004
0.04-
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!
i t
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4.0
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O0
tgYO
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lm/18
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WFil
~
14)44
Vl[A(q OIr 8AMPLI ¢OLLII[¢VI~I
Fig. 3. The cffcctof age and time on the body burden of some chlorinated hydrocarbons in Canadians.
Chlorinated hydrocarbon residues in adipose tissue
275
while in 1972 significantly higher residue levels o f PCBs, oxychlordane and tnonachlor were recorded for males. HCB residues were significantly higher for females than for males in 1976 and 1985. In addition the fl H C H residue level was lower in the male than the female population during 1985. Figure 3 illustrates the trends in adipose tissue burden o f each residue with time as related to arbitrarily chosen age groups. In general, all surveys show that residue levels tend to increase with age, although in some instances as for example with dieldrin and o,p'-DDT, the distinction becomes less noticeable at very low levels. For the 26-50-year age group, t-nonachlor residue levels were significantly higher in 1972 than in later surveys, while oxychlordane residues significantly decreased since 1976 for all age groups. Both o,p'-DDT and heptachlor epoxide levels decreased significantly after 1976. Residue levels o f dieldrin, p,p'-DDE and p , p ' - D D T all showed a downward trend over the years, although not always significantly, especially between 1972 and 1976. In general no definite trend was observed for PCBs, HCB and Z H C H levels in the various age groups, except that the 1985 residue levels were always lower, sometimes significantly, than in previous surveys for all age groups. Table 2 summarizes the adipose tissue body burden o f Canadians for those residues, which were consistently measured since 1969. Although the total residue levels differed slightly a m o n g the various regions o f the country, a definite d o w n w a r d trend was observed in each region and the country as a whole, between 1969 and 1985. TABLE 2 Geographical Distribution of the Chlorinated I lydrocarbon Body Burden of Canadians
/~g/g Adipose tissue
Provinces
Total residue,¢~ 1969
1972
1976
1985
All Easternb Quebec Ontario Central ~
4'5 4. I 4.6 4.9 5.1
2"7 2"6 2'6 2"5 2-2
2"0 !- i 2.2 1'9 2.7
1'3 1.0 1.9 1.0 NA"
Western"
3.7
3"5
2" I
I.I
° Sum of mean values of 7 HCH. hcptachlor epoxidc, dicldrin, p,p'.DDE and p,p'-DDT. b Newfoundland, Prince Edward Island, New Brunswick and Nova Scotia. c Manitoba and Saskatchewan. d Alberta and British Columbia. • NA = not available.
276
dos Mes
DISCUSSION In many industrialized nations the use of various organochlorine pesticides such as p , p ' - D D T or other widely used industrial chemicals such as PCBs, have been severely restricted. For example, in Canada, where the use ofp,p'DDT was gradually restricted from 1969 to 1978 and completely banned on all foods in 1978, a continuous decrease in the human adipose tissue-burden of this agricultural chemical has been observed as shown in Fig. 1. PCBs followed a similar pattern after its use was restricted in 1977. Surveys carried out previous to 1977 showed no decrease in residue levels of this ubiquitous contaminant in the Canadian population, but by 1985 however, the Canadian adipose tissue burden had been halved. This trend of declining residues in human fat deposits was also observed in other countries. In the United Kingdom, Abbott et ai. (1985) observed a steady decrease of p , p ' - D D T residue levels from 1963 to 1983. In the USA, the number of people with PCB levels >31~g/g in their body fat decreased between 1976 and 1981 (Kee, 1983). Levels of HCB in the Canadian population decreased from 1976 to 1985, while in the US general population, this residue was lower in 1983 than in previous years (Cooper, 1986). Similarly, the [~ HCH residue levels in adipose tissue of Canadians decreased significantly since 1976, as they did elsewhere (Abbott et aL, 1985; Cooper, 1986). Although many residues showed similar decreases, not all residues declined with time. Residue levels of t-nonachlor in the Canadian population were not significantly different in 1985 from those in 1972. The same observation was made for levels of this chemical in the general population of the USA between 1974 and 1983 (Cooper, 1986). This may reflect the relative stability of this compound and/or the continued exposure of the North American population to chlordane. There appears to be no consistent and significant differences in residue levels between the sexes. Although in Canadian surveys up to 1972, the levels ofdieldrin and p,p'-DDE were significantly higher in adipose tissue of males than females, results from later surveys (1976, 1985) did not support these earlier findings. In addition Williams et ttl. (1988) found higher levels ofp,p'DDE in females than in males of six Ontario municipalities. Furthermore, HCB residue levels were higher in females than males during the last two Canadian surveys as shown in Fig. 2. At the same time however, Robinson et al. (1986) reported no differences between the sexes in the USA, while again other studies showed lower levels of this residue in females (Dejonckheere et al., 1978; Mori et al., 1983). Without information on the number ofchildren breastfed and a comparison of identical age groups, the obvious lack of consistent higher residue levels in males may not necessarily contradict the postulation that significant amounts of residues are mobilized in females
Chlorinated hydrocarbon residues in adipose tissue
277
and secreted during lactation. The data presented in this paper indicate that in general the adipose tissue-burden o f the reported residues in Canadians increase with age. However, the possible loss of fatty deposits during advanced age m a y be reflected to some extent in the diminishing n u m b e r of residues which are significantly different between the 26-50 and > 51 age groups. Similarly, M u s s a l o - R a u h a m a a et al. (1984), who also found a significant correlation between residue concentration in adipose tissue and age, noted that this significance decreased with age and observed some very low residue levels a m o n g older people. Age did not appear to affect the depletion of residues from the body over the years. A l t h o u g h the rates of elimination may differ, the same general d o w n w a r d trend was observed regardless of age group.
REFERENCES Abbott, D. C., Goulding, R., Holmes, D. C. & Hoodless, R. A. (1985). Organochlorine pesticide residues in human fat in the United Kingdom 1982-1983. Human Toxicol., 4, 435-45. Biros, F. J. & Enos, H. F. (1973). Oxychlordane residues in human adipose tissue. Bull Environ. Contain. Toxh'oL, 10, 257-60. Cooper, C., ed. (1986). Human residue monitoring results show lower levels. Pesticide & Toxic Chemicals News, 14(16) 13. Dejonckheere, W., Steurbaut, W., Verstraeten, R. & Kips, R. tl. (1978). Residues of organochlorine pesticides in human fat in Belgium. Toxicol. Eur. Res., 2, 93-8. Holt, R. L., Cruse, S. & Greer, E. S. (1986). Pesticide and polyehlorinated biphenyl residues in human adipose tissue from Northeast Louisiana. Bull Environ. Contain. ToxicoL, 36, 651-5. Howell, D. E. (1948). A case of DDT storage in human fat. Proc. Oklahoma Acad. Sci., 29, 31-2. Kee, M. (1983). Polychlorinated biphenyls in human tissue. Nature, 303, 653. Mes, J., Campbell, D. S., Robinson, R. N. & Davies, D. J. A. (1977). Polychlorinated biphenyl and organochlorine pesticide residues in adipose tissue of Canadians. Bull. Environ. Contain. Toxicol., 17, 196-203. Mes, J., Davies, D. J. & Turton, D. (1982). Polychlorinated biphenyl and other chlorinated hydrocarbon residues in adipose tissue of Canadians. Bull. Environ. Contain. ToxicoL, 28, 97-104. Mes, J., Davies, D. J. & Turton, D. (1985). Environmental contaminants in human fat: a comparison between accidental and non-accidental causes of death. EcotoxicoL Environ. Safety, 10, 70-4. Mes, J., Marehand, L. & Davies, D. J. (in press). Some chlorinated hydrocarbon residues in adipose tissue of Canadians. Bull. Environ. Contain. Toxicol. Mori, Y., Kikuta, M., Okinaga, E. & Okura, T. (1983). Levels of PCBs and organochlorine pesticides in human adipose tissue collected in Ehime prefecture. Bull Environ. Contain. ToxicoL, 30, 74-9.
278
,los Mes
M ussalo- Rauhamaao H., Pyysalo, H. & M oila nen, R. (1984). I nfl uence of diet and other factors on the levels of organochlorine compounds in human adipose tissue in Finland. J. Toxicoi. Environ. Health, 13, 689-704. Ritcey, W. R., Savary, J. & McCully, K. A. (1973). Organochlorine insecticide residues in human adipose tissue of Canadians. Can. J. Publ. Health, 64, 380-86. Robinson, P. E., Leczynski, B. A., Kutz, F. W. & Returners, J. C. (1986). An Evah~ation of Hexachloroben:ene Body-Burden Le~'els in the General Population of the USA. Proceedings of an International Symposium, Vol. 77. IARC Scientific Publications, Lyon, France, pp. 183-92. Siddiqui, M. K, J., Saxena, M. C. & K rishna M urti, C. R. (1981). Storage of DDT and BHC in adipose tissue of Indian males. Intern. J. Environ. Anal. Chem., 10, 197-204. van Dyk, L. P., Lotter, L. H., Mullen, J. E. C. & deKock, A. (1987). Organochlorine insecticide residues in human fat and milk samples in South Africa. Clwmosphere, 16, 705-1 !. Williams, D. T., LeBel, G. L. & Junkins, E.(1988). Organohalogen residues in human adipose autopsy samples from six Ontario municipalities. J. Assoc. Ofll Anal. Chem., 71,410-14. Yobs, A. R. (1972). Levels of polychlorinated biphenyls in adipose tissue of the general population of the nation. Etwiron. ftcalth Perspect., April, 79-81.
Trends in the Levels of Some Chlorinated Hydrocarbon Residues in Adipose Tissue of Canadians Jos M e s Food Research Division, Bureau of Chemical Safety, Food Directorate, Health Protection Branch, Health and Welfare Canada, Ottawa, Canada KIA OL2
(Received I I October 1989; accepted 2 February 1990) A BSTRA C T Trends in the levels of hexachloroben=ene, hexachloroo'clohexanes. oxychlordane, t-nonachlor, heptachlor epoxide, dieldrin. DDTs and polychlorinated biphenyls in adipose tissue of the Canadian population were followed from 1969 to 1985. Residues of lindane, dieldrin and p,p'-DDT continuously and significantly (P <0.025) decreased during that time, coincMing with restrictions on their use. Other residues also decreased significantly between 1969 and 1985, although not always continuously, while t-nonachlor levels did not change significantly since 1972. In general no consistent and/or significant differences were obserw.d between the sexes, but in some instances differences were found for a particular residue in a given year. Three arbitrarily chosen age groups (0-25; 26-50 and > 51 years) showed a downward trend in residue levels with time. The resuhs of the surveys also indicate an increase in adipose tissue burden of chlorinated hydrocarbons with age. but this increase became apparently less significant with increasing age.
INTRODUCTION Ever since the determination of D D T residues in human fat by Howell (1948), many different attempts have been made to study not only DDT, but also many other chlorinated hydrocarbons in human adipose tissue as an i n d i c a t i o n of non-occupational exposure. Some investigators restricted their studies to selected compounds, a given sex or a specific population. For 269 EnL'iron. Pollut. 0269-7491/90/$03-50 ©
Printcd in Great Britain
1990 Elsevier Science Publishers Ltd. England.
.los Mes
270
example Yobs (1972) determined polychlorinated biphenyls (PCBs) and Biros & Enos (1973) determined oxychlordane (OCl) in the general population of the USA, while Siddiqui et al. (1981) and Mod et al. (1983) restricted their investigations of organochlorine pesticides to Indian males and one of the Japanese prefectures, respectively. Other researchers studied chlorinated hydrocarbon residues in human populations at regular intervals in order to establish trends in the adipose tissue burden of these residues. Abbott et al. (1985), for example, followed the trends of several chlorinated hydrocarbon residues in the population of the United Kingdom from 1963 to 1983, while Holt et al. 0986) studied several residues in a north-east Louisiana population from 1977 to 1984. Similarly van Dyk et al. (1987) followed the exposure of specific South African subpopulations to organochlorine pesticides from 1973 to 1982. In Canada, nation-wide surveys of chlorinated hydrocarbon residues were carried out in 1969 (Ritcey et al., 1973), 1972 (Mes et ai., 1977), 1976 (Mes et al., 1982) and 1985 (Mes el al., submitted). The results of these surveys are presented in this paper as a function of time, and the effects of such parameters as age and sex are explored.
MATERIALS AND METHODS The collection of abdominal fat samples during the 1969, 1972 and 1976 surveys was restricted to accident victims. During the 1985 monitoring program this restriction was lifted however, after Mes et al. (1985) reported no significant differences in residue levels from victims of accidental and non-accidental death. Although sampling details have been described earlier (Ritcey et al., 1973; Mes et al., 1977, 1982), some pertinent information is TABLE I Sampling Information
Year of sample eolh'ction
1969 1972 1976 1985
Number of samples Males
159 I11 53 81
Females
59 57 45 27
• NA ffi not available. b No age given in 4 samples.
Age groups (years) 0-25
26-50
> 51
41 49 33 28
76 65 41 41
97 54 24 39
Total
Age range ()'ears)
Mean % flit
218 b 168 98 108
ff5-89 9-88 16-97 3-85
NA" 81 NA 90
Chlorinated hydrocarbon residues in adipose tissue
271
summarized in Table 1. Adipose tissue samples were obtained from across Canada and every effort was made to collect them from as many different locations as possible. Nevertheless most samples came from large urban centers. This did not mean, however, that rural samples were excluded, since autopsies of accidental deaths in rural areas are performed mainly in larger cities. Unfortunately, in 1985 no specimens were available from the provinces of Manitoba and Saskatchewan. Although modifications to the analytical methodology were made over the years, the essential steps remained the same and are briefly outlined as follows. Fat samples were extracted with benzene: acetone (1 : 19, v/v) and the lipids removed by low temperature precipitation during the 1969, 1972 and 1976 surveys and by Florisil ® column chromatography during the 1985 survey. In addition, Florisil was used in all surveys to separate PCBs as much as possible from other chlorinated hydrocarbon residues. PCBs were partially separated on a packed gas chromatographic (GC) column, using 6% OV-210 + 4% SE-30 as stationary phase or one of similar polarity. Other chlorinated hydrocarbons were also separated and identified on the same stationary phase, except for the/~ and 7 hexachlorocyclohexane (HCH) isomers, for which a 5% OV-210 column was used. Only during the 1985 survey were c o m p o u n d s other than PCBs separated and identified on a 30 m x 0.24 mm (i.d.) capillary column with DB-5 (J & W Scientific) as the bonded phase, in all surveys the PCBs were quantitated by summation of all peaks after p,p'-DDE in the sample chromatogram, corresponding to similar ones in the Aroclor 1260 standard. In the 1969 and 1972 surveys, residues were confirmed by thin layer chromatography, while during the last two surveys a combination of GC and mass spectrometry (MS) was used. The data were statistically evaluated using the Student's t-test. RESULTS The 1976 and 1985 surveys indicated a skewed distribution of residue levels, which may also be the case in the earlier surveys, but could not be verified since the individual data are no longer available. Therefore, the results of these earlier surveys (1969 and 1972) could not be expressed as geometric means or medians. Consequently, only arithmetic means were used to illustrate temporal trends. This approach excluded, however, the use of any substantial statistical trend analysis and only the rather 'crude' Student's ttest was used. The histograms in Fig. l represent the arithmetic means of residue levels in adipose tissue of Canadians between 1969 and 1985. Statistically significant differences (P < 0-025) were observed for all residues Floridin Co.
272
.los Mes
O,~Oo O,IS-
t,i
r'l ,ooo
.
lOT2 ~JleTg • lg88
L
p'cmo ~
p~Oo¢
Fig. I. Trends in body burden of some chlorinated hydrocarbons in adipose tissue of Canadians from 1969 to 1985.
between the years 1972 and 1985, except for/-nonachlor (t-NCI). Three of the reported residues, namely 7 HCH, dieldrin (HEOD) and p,p'-DDT decreased continuously and significantly from 1969 to 1985. Although residue levels ofp,p'-DDE also continuously decreased over that period of time, the decrease between 1972 and 1976 was not statistically significant. Heptachlor epoxide (HpEp) levels remained essentially the same between 1969 and 1976, but were significantly lower in 1985. A noticeable increase in /~ HCH residue levels occurred in 1976, for which no ready explanation is available. Figure 2 illustrates trends in residue levels of males and females between 1969 and 1985. Only residues of dieldrin and p,p'-DDT decreased steadily
273
Chlorinated hydrocarbon residues in adipose tissue MALE 1"7 11410 I~1 10F1
•
,o.s
.
-1.0
ioo 0.10 -
--~
FEMALE
¢m
[] ~vo 0.11-
•
Hell
"HC:H
OCl
.~o
,OILS
I-NCl
HpEI)
HIOD o.p**OOT
PGIIo p.Fl-OOl[ p,;C..OOT
Fig. 2. Trendsin body burden of somechlorinated hydrocarbons in body fat of Canadian males and females from 1969 to 1985. and significantly (P < 0-025) from 1969 to 1985 in both males and females. The high level o f Z H C H in males was due to the fl H C H component of these residues. The apparent decrease of PCB levels in males was only significant
between 1976 and 1985. The p,p'-DDE residue level in males decreased significantly until 1976, while the female adipose tissue burden of this residue did not significantly change from 1972 to 1985. No significant changes in residue levels were observed for hexachlorobenzene (HCB), heptachlor epoxide and o,p'-DDT in both sexes between 1972 and 1976. In addition, levels of PCBs and oxychlordane (OCI) in adipose tissue of males did not change significantly over the same period of time. Few differences in residue levels between males and females were statistically significant within a given survey. The p,p'-DDE and dieldrin levels were significantly different between the sexes in 1969 and 1972 only,
274
Jos Mes
0.04,
- 0.O4
0.04-
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0qPTACPq.O~ [POX H ~
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NC0
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,004
0.04-
- 0.Odl
!
i t
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! -L8
1.S-
I ~
O.O-
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4.0
-0.40
11.2.
.0.Jr
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0.~1
1.4-
,0.041
O0
tgYO
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~
lm/18
lS/q
WFil
~
14)44
Vl[A(q OIr 8AMPLI ¢OLLII[¢VI~I
Fig. 3. The cffcctof age and time on the body burden of some chlorinated hydrocarbons in Canadians.
Chlorinated hydrocarbon residues in adipose tissue
275
while in 1972 significantly higher residue levels o f PCBs, oxychlordane and tnonachlor were recorded for males. HCB residues were significantly higher for females than for males in 1976 and 1985. In addition the fl H C H residue level was lower in the male than the female population during 1985. Figure 3 illustrates the trends in adipose tissue burden o f each residue with time as related to arbitrarily chosen age groups. In general, all surveys show that residue levels tend to increase with age, although in some instances as for example with dieldrin and o,p'-DDT, the distinction becomes less noticeable at very low levels. For the 26-50-year age group, t-nonachlor residue levels were significantly higher in 1972 than in later surveys, while oxychlordane residues significantly decreased since 1976 for all age groups. Both o,p'-DDT and heptachlor epoxide levels decreased significantly after 1976. Residue levels o f dieldrin, p,p'-DDE and p , p ' - D D T all showed a downward trend over the years, although not always significantly, especially between 1972 and 1976. In general no definite trend was observed for PCBs, HCB and Z H C H levels in the various age groups, except that the 1985 residue levels were always lower, sometimes significantly, than in previous surveys for all age groups. Table 2 summarizes the adipose tissue body burden o f Canadians for those residues, which were consistently measured since 1969. Although the total residue levels differed slightly a m o n g the various regions o f the country, a definite d o w n w a r d trend was observed in each region and the country as a whole, between 1969 and 1985. TABLE 2 Geographical Distribution of the Chlorinated I lydrocarbon Body Burden of Canadians
/~g/g Adipose tissue
Provinces
Total residue,¢~ 1969
1972
1976
1985
All Easternb Quebec Ontario Central ~
4'5 4. I 4.6 4.9 5.1
2"7 2"6 2'6 2"5 2-2
2"0 !- i 2.2 1'9 2.7
1'3 1.0 1.9 1.0 NA"
Western"
3.7
3"5
2" I
I.I
° Sum of mean values of 7 HCH. hcptachlor epoxidc, dicldrin, p,p'.DDE and p,p'-DDT. b Newfoundland, Prince Edward Island, New Brunswick and Nova Scotia. c Manitoba and Saskatchewan. d Alberta and British Columbia. • NA = not available.
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DISCUSSION In many industrialized nations the use of various organochlorine pesticides such as p , p ' - D D T or other widely used industrial chemicals such as PCBs, have been severely restricted. For example, in Canada, where the use ofp,p'DDT was gradually restricted from 1969 to 1978 and completely banned on all foods in 1978, a continuous decrease in the human adipose tissue-burden of this agricultural chemical has been observed as shown in Fig. 1. PCBs followed a similar pattern after its use was restricted in 1977. Surveys carried out previous to 1977 showed no decrease in residue levels of this ubiquitous contaminant in the Canadian population, but by 1985 however, the Canadian adipose tissue burden had been halved. This trend of declining residues in human fat deposits was also observed in other countries. In the United Kingdom, Abbott et ai. (1985) observed a steady decrease of p , p ' - D D T residue levels from 1963 to 1983. In the USA, the number of people with PCB levels >31~g/g in their body fat decreased between 1976 and 1981 (Kee, 1983). Levels of HCB in the Canadian population decreased from 1976 to 1985, while in the US general population, this residue was lower in 1983 than in previous years (Cooper, 1986). Similarly, the [~ HCH residue levels in adipose tissue of Canadians decreased significantly since 1976, as they did elsewhere (Abbott et aL, 1985; Cooper, 1986). Although many residues showed similar decreases, not all residues declined with time. Residue levels of t-nonachlor in the Canadian population were not significantly different in 1985 from those in 1972. The same observation was made for levels of this chemical in the general population of the USA between 1974 and 1983 (Cooper, 1986). This may reflect the relative stability of this compound and/or the continued exposure of the North American population to chlordane. There appears to be no consistent and significant differences in residue levels between the sexes. Although in Canadian surveys up to 1972, the levels ofdieldrin and p,p'-DDE were significantly higher in adipose tissue of males than females, results from later surveys (1976, 1985) did not support these earlier findings. In addition Williams et ttl. (1988) found higher levels ofp,p'DDE in females than in males of six Ontario municipalities. Furthermore, HCB residue levels were higher in females than males during the last two Canadian surveys as shown in Fig. 2. At the same time however, Robinson et al. (1986) reported no differences between the sexes in the USA, while again other studies showed lower levels of this residue in females (Dejonckheere et al., 1978; Mori et al., 1983). Without information on the number ofchildren breastfed and a comparison of identical age groups, the obvious lack of consistent higher residue levels in males may not necessarily contradict the postulation that significant amounts of residues are mobilized in females
Chlorinated hydrocarbon residues in adipose tissue
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and secreted during lactation. The data presented in this paper indicate that in general the adipose tissue-burden o f the reported residues in Canadians increase with age. However, the possible loss of fatty deposits during advanced age m a y be reflected to some extent in the diminishing n u m b e r of residues which are significantly different between the 26-50 and > 51 age groups. Similarly, M u s s a l o - R a u h a m a a et al. (1984), who also found a significant correlation between residue concentration in adipose tissue and age, noted that this significance decreased with age and observed some very low residue levels a m o n g older people. Age did not appear to affect the depletion of residues from the body over the years. A l t h o u g h the rates of elimination may differ, the same general d o w n w a r d trend was observed regardless of age group.
REFERENCES Abbott, D. C., Goulding, R., Holmes, D. C. & Hoodless, R. A. (1985). Organochlorine pesticide residues in human fat in the United Kingdom 1982-1983. Human Toxicol., 4, 435-45. Biros, F. J. & Enos, H. F. (1973). Oxychlordane residues in human adipose tissue. Bull Environ. Contain. Toxh'oL, 10, 257-60. Cooper, C., ed. (1986). Human residue monitoring results show lower levels. Pesticide & Toxic Chemicals News, 14(16) 13. Dejonckheere, W., Steurbaut, W., Verstraeten, R. & Kips, R. tl. (1978). Residues of organochlorine pesticides in human fat in Belgium. Toxicol. Eur. Res., 2, 93-8. Holt, R. L., Cruse, S. & Greer, E. S. (1986). Pesticide and polyehlorinated biphenyl residues in human adipose tissue from Northeast Louisiana. Bull Environ. Contain. ToxicoL, 36, 651-5. Howell, D. E. (1948). A case of DDT storage in human fat. Proc. Oklahoma Acad. Sci., 29, 31-2. Kee, M. (1983). Polychlorinated biphenyls in human tissue. Nature, 303, 653. Mes, J., Campbell, D. S., Robinson, R. N. & Davies, D. J. A. (1977). Polychlorinated biphenyl and organochlorine pesticide residues in adipose tissue of Canadians. Bull. Environ. Contain. Toxicol., 17, 196-203. Mes, J., Davies, D. J. & Turton, D. (1982). Polychlorinated biphenyl and other chlorinated hydrocarbon residues in adipose tissue of Canadians. Bull. Environ. Contain. ToxicoL, 28, 97-104. Mes, J., Davies, D. J. & Turton, D. (1985). Environmental contaminants in human fat: a comparison between accidental and non-accidental causes of death. EcotoxicoL Environ. Safety, 10, 70-4. Mes, J., Marehand, L. & Davies, D. J. (in press). Some chlorinated hydrocarbon residues in adipose tissue of Canadians. Bull. Environ. Contain. Toxicol. Mori, Y., Kikuta, M., Okinaga, E. & Okura, T. (1983). Levels of PCBs and organochlorine pesticides in human adipose tissue collected in Ehime prefecture. Bull Environ. Contain. ToxicoL, 30, 74-9.
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M ussalo- Rauhamaao H., Pyysalo, H. & M oila nen, R. (1984). I nfl uence of diet and other factors on the levels of organochlorine compounds in human adipose tissue in Finland. J. Toxicoi. Environ. Health, 13, 689-704. Ritcey, W. R., Savary, J. & McCully, K. A. (1973). Organochlorine insecticide residues in human adipose tissue of Canadians. Can. J. Publ. Health, 64, 380-86. Robinson, P. E., Leczynski, B. A., Kutz, F. W. & Returners, J. C. (1986). An Evah~ation of Hexachloroben:ene Body-Burden Le~'els in the General Population of the USA. Proceedings of an International Symposium, Vol. 77. IARC Scientific Publications, Lyon, France, pp. 183-92. Siddiqui, M. K, J., Saxena, M. C. & K rishna M urti, C. R. (1981). Storage of DDT and BHC in adipose tissue of Indian males. Intern. J. Environ. Anal. Chem., 10, 197-204. van Dyk, L. P., Lotter, L. H., Mullen, J. E. C. & deKock, A. (1987). Organochlorine insecticide residues in human fat and milk samples in South Africa. Clwmosphere, 16, 705-1 !. Williams, D. T., LeBel, G. L. & Junkins, E.(1988). Organohalogen residues in human adipose autopsy samples from six Ontario municipalities. J. Assoc. Ofll Anal. Chem., 71,410-14. Yobs, A. R. (1972). Levels of polychlorinated biphenyls in adipose tissue of the general population of the nation. Etwiron. ftcalth Perspect., April, 79-81.