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Certain organochlorine and organobromine contaminants in Swedish human milk in perspective of past 20–30 years
Chemosphere 40 (2000) 1111±1123
Certain organochlorine and organobromine contaminants in Swedish human milk in perspective of past 20±30 years Koidu Noren *, Daiva Meironyte Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden
Abstract The investigations of organochlorine compounds in breast milk from women living in the Stockholm region started in 1967. The present study summarises the investigations of polychlorinated biphenyls (PCBs), naphthalenes (PCNs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), polybrominated diphenyl ethers (PBDEs) and pesticides (DDT, DDE, hexachlorobenzene, dieldrin) as well as methylsulfonyl metabolites of PCBs and DDE in human milk sampled during dierent periods up to 1997. During the course of 20±30 yr the levels of organochlorine compounds in human milk have decreased to various extent. A decrease to the half of the original concentration was attained in the range of 4±17 yr periods. On the contrary to the organochlorine compounds, the concentrations of PBDEs have increased during the period 1972±1997, indicating a doubling of the levels by 5 yr. The levels re¯ect the environmental contamination and background levels in the population. The accumulation and ongoing increase in the levels of PBDEs calls for immediate measures to stop the environmental pollution and human exposure to PBDEs. Ó 2000 Elsevier Science Ltd. All rights reserved. Keywords: PCB; PCDD; PCDF; Pesticides; Methylsulfonyl metabolites; PBDE; Flame retardant
1. Introduction The production of most of the organochlorine compounds, which are found as pollutants in our environment, started in the 1930s. The found insecticidal properties of DDT led to development of a number of organochlorine pesticides, e.g., aldrin, dieldrin, chlordane, heptachlor, lindane, pentachlorophenol. Other organochlorine products became of industrial importance due to their stability and isolating properties. The most widely used of such products were polychlorinated biphenyls (PCBs), but also polychlorinated naphthalenes (PCNs) were manufactured for industrial applications, e.g., capacitor dielectrics, cutting oils, plasticisers in dyes and sealants, wire and cable coatings (de Voogt and Brinkman, 1989; Hayward, 1998). PCNs were introduced in 1909 and became of revived importance in * Corresponding author. Tel.: +46-8-728-6400; fax: +46-830-44-52.
1930s (Hayward, 1998). The production of PCNs is not well documented but the amount was less than that of PCBs (de Voogt and Brinkman, 1989). The extensive use of organochlorine compounds has released an unprecedented number of toxic substances into the environment. From the 1970s on, many countries have applied prohibitions on the use of speci®c organochlorine compounds. Another group of pollutants, the polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), are found as by-products in other chemicals and formed in various combustion processes. Identi®ed sources are, e.g., waste incineration, iron and steel production, pulp bleaching and chloralkali industry (Rappe, 1994). Measures have been taken in order to reduced the formation of such compounds. Contrary to the organochlorine compounds, the use of polybrominated diphenyl ethers (PBDEs) increased in the European Economic Community (EEC) during 1980s (Environmental Health Criteria, 1994). These products have a wide application as ¯ame retardants,
0045-6535/00/$ - see front matter Ó 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 0 4 5 - 6 5 3 5 ( 9 9 ) 0 0 3 6 0 - 4
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K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
especially in polymers used in electronics (TVs, computers), and textiles (Environmental Health Criteria, 1994; Risk Assessment of Polybrominated Diphenyl Ethers, 1994). PBDEs are mixed into the material they are used in. Since PBDEs are not chemically bound they may migrate from the material and PBDEs are now widely dispersed in the environment. Like the organochlorine compounds, PBDEs have been found in, e.g., ®sh (Andersson and Blomkvist, 1981; Jansson et al., 1987; Sellstr om et al., 1993) and mammals including humans (Haglund et al., 1997; Klasson-Wehler et al., 1997; Darnerud et al., 1998; Meironyte et al., 1999; Sj odin et al., 1999). Persistent lipophilic organohalogen environmental contaminants accumulate in the human body. The elimination of such compounds and their lipophilic metabolites from body fat is very low. Due to the relatively high fat content of breast milk, the lipophilic compounds are transferred to the milk. The levels in milk are strongly correlated to the fat content of the milk (Noren, 1983a, 1988) and re¯ect the accumulated levels in the adipose tissue. Accordingly, milk constitutes a suitable matrix for studies of long term exposure to organohalogen pollutants and for studies of time related trends in environmental contamination. The present survey of organohalogen compounds in human milk from the Stockholm region includes both previously reported data and recent results. For most of the compounds the levels cover the period from 1972 to 1992 or 1997. However, the ®rst analyses of DDT, DDE, dieldrin and PCBs were performed in 1967. The early investigations of pesticides and PCBs have been completed by congener speci®c analysis of PCBs, PCDDs, PCDFs, PCNs, methylsulfonyl metabolites of DDE and PCBs and PBDEs.
2. Materials and methods The milk was obtained from healthy native Swedish mothers living in the Stockholm region. The ®rst samples were collected in 1967 but only from 1972 on, milk was banked for coming reanalysis. From 1986 on, the donors were non-smokers and the milk was collected during the ®rst three months after delivery. Equal amounts of milk from individual mothers were mixed to constitute pooled samples. In order to get comparable samples, the composition of pools was kept as equal to that of the early sampled milk as possible. In the pools 55±75% of the milk was from mothers nursing their ®rst infant. The average age of the mothers was 27±28 yr in the period 1972±1985, 29±30 yr in 1988±1994 and 30±31 yr in 1996±1997. The age of the mothers in 1967 and 1969 is not documented. The increase in age is consistent with the general increase of the age of the mothers giving
birth in Sweden (Population statistics, 1996). The milk was stored at )20°C. The details of the analytical procedures for organochlorine compounds have been described previously and Noren, 1970; Noren and (Noren, 1983a; West oo Sj ovall, 1987; Noren et al., 1996). Puri®cation and separation of compounds were made by chromatography on aluminium oxide, silica gel, activated charcoal and gel permeation chromatography. In the analysis of samples from 1994 to 1997, instead of activated charcoal the separation of planar compounds was performed by HPLC on a Cosmosil 5-PYE column (2-(1-pyrenyl)ethyldimethylsilylated silica gel: 250 ´ 4.6 mm, 0.5 lm particle size) from Nacalai Tesque (Kyoto, Japan) (as described by Weistrand and Noren, 1998). Identi®cations and quanti®cations were made by gas chromatography electron capture detection and gas chromatography/mass spectrometry using selected ion recording. Slight modi®cation of the method enabled the analysis of PBDEs (Meironyte et al., 1999). Total PCBs refer to determination of the concentrations by comparison to the PCB product Clophen A50 (Bayer, Leverkusen, Germany) using a packed column et al., in the analysis by gas chromatography (West oo and Noren, 1970; Noren, 1983a). By the 1970; West oo time when capillary columns and standards of individual PCB congeners became available, the concentrations of PCB were determined both as total PCBs using a packed column and as speci®c PCB congeners using a capillary column and 18 PCB congeners as standards for comparison (Noren et al., 1990; Lunden and Noren, 1998). Congener speci®c analyses were performed when reanalysing archived samples. The sum of PCB congeners was on an average 68% of the total PCBs. From 1994 on, only capillary columns were used and the total PCBs were calculated from the sum of PCB congeners on the above assumption. The changes in the levels of organohalogen compounds were examined for adaptation to a ®rst order rate expression: ÿdC=dt k C; which on integration yields: ln C0 =Ct k t, where C0 is the concentration at the ®rst investigation, Ct the concentration at the last investigation, k the constant and t is the time range of investigations. The rate of decrease is given as the time to halve the concentration, decline half-time, tdec 1=2 , the time increase to the double concentration as tinc 2 and correlation to the exponential curve as R2 . 3. Results and discussion The present report includes previously reported re et al., 1970; West and Noren, 1972, sults (West oo oo
ng/g lipid 7.98
ng/g lipid
ng/g lipid 9.24
Sum MeSO2 ±CBs
790
ng/g lipid 4.56
Noren et al. (1996) 199
65 780 880
ng/g lipid 29
and West oo Noren (1970) 431
ng/g lipid 1055 185 18 9 96 14 19 125 17d
Noren (1988) and Noren and Lunden (1991) 973
1980
84 910
ng/g lipid
ng/g lipid 1130 210 20 8 110 16 22 120
Noren and Lunden (1991) 805
1979
8 1 31 134 152 13 2 3
ng/g lipid
ng/g lipid 1270 270 22 8 120 16 21 120
Noren and Lunden (1991) 745
1978
16 1 46 177 197 19 3 4
ng/g lipid 22
and West oo Noren (1970) 156
ng/g lipid 1500 340 25 <8 130 16c 19c 110 36c
1500
Noren (1988) and Noren (1983b)
1976
No. of mothers
810
ng/g lipid
220
ng/g lipid 1800 470 38 <8 120
250
Noren (1983b)
1974
Noren et al. (1996) 153
600
ng/g lipid 34 4 11 15 1 60 190 215 20 4 11 41 88 1090
and Noren West oo (1970) 135
ng/g lipid 2420 710 49 7 280 19 20 120 30
227
Noren (1988)
1972
Noren et al. (1996) 75
Reference
CB-28e CB-52 CB-101 CB-105 CB-114 CB-118 CB-138 CB-153 CB-156 CB-157 CB-167 CB-170/190 CB-180 Total PCBs
No. of mothers
Reference
500
ng/g lipid 1700 1020 67b
ng/g lipid 2000 1300 76a
ng/g lipid
75
210
No. of mothers
ng/g lipid
and West oo Noren (1972)
Reference
p, p0 -DDE p, p0 -DDT Dieldrin a-HCH b-HCH Oxychlordane trans-Nonachlor HCB Pentachlorophenol
1968/1969
1967
and West oo Noren (1972)
Year
Table 1 Concentrations of organohalogen contaminants in Swedish human milk, 1967±1997
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123 1113
ng/g lipid 369 42
33
ng/g lipid 480 47
12 17 40
102
ng/g lipid 500 61 10 3 72 13 13 37 12
Noren (1988)
102
ng/g lipid 22
No. of mothers
p, p0 -DDE p, p0 -DDT Dieldrin a-HCH b-HCH Oxychlordane trans-Nonachlor HCB Pentachlorophenol
Reference
No. of mothers
PCBs CB-28 CN-52 CB-101
ng/g lipid 9
ng/g lipid 9 1 2
Lunden and Noren (1998) 60
Lunden and Noren (1998), present 40
et al. West oo (1970) 140
Lunden and Noren (1998) 120
1990
1988/1989
1984/1985
ng/g lipid 6 1 2
Lunden and Noren (1998) 60
27
ng/g lipid 255 36
Lunden and Noren (1998) 40
ng/g lipid 4 1 2
Lunden and Noren (1998) 40
31
ng/g lipid 227 22
Lunden and Noren (1998) 20
1992
pg/g lipid 825 132
Sum PCDDs Sum PCDFs
Noren (1988)
pg/g lipid 519 71
75
No. of mothers
Reference
Noren (1988) and et al. West oo (1970) 204
et al. West oo (1970)
Reference
Year
ng/g lipid 0.28
et al. West oo (1970) 78 ng/g lipid 1.73
1976
ng/g lipid 0.07
1991
1974
Sum PBDEs
et al. West oo (1970) 75 ng/g lipid 3.08
1972
No. of mothers
1968/1969
Meironyte et al. (1999) 78
1967
Meironyte et al. (1999) 75
Reference
Sum PCN
No. of mothers
Reference
Year
Table 1 (Continued)
ng/g lipid 5 0 2
20
Present
15
ng/g lipid 199 12
20
Present
1994
1978
ng/g lipid 3 1 1
20
Present
14
ng/g lip 164 14
20
Present
1996
1979
ng/g lipid 4 0 1
40
Present
12
ng/g lipid 129 14
40
Present
1997
pg/g lipid 448 40
Noren (1988) and et al. West oo (1970) 431
ng/g lipid 0.48
Meironyte et al. (1999) 116
et al. West oo (1970) 116 ng/g lipid 1.23
1980
1114 K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
Sum MeSO2 ±CBs
Present
ng/g lipid 1.21
140 pg/g lipid 373 36
ng/g lipid 0.72
Noren (1988)
102
pg/g lipid 349 37
No. of mothers
Sum PBDEs
Reference
No. of mothers
Sum PCDDs Sum PCDFs
b
pg/g lipid 429 31
Lunden and Noren (1998) 60
Meironyte et al. (1999) 20
Sum PCN
Meironyte et al. (1999) 102
ng/g lipid 0.71
ng/g lipid 0.89
No. of mothers
Reference
Lunden and Noren (1998) 60
510
Lunden and Noren (1998) 102
90 mothers. 45 mothers. c 245 mothers. d 340 mothers. e Numbering of PCBs according to Ballschmiter et al. (1993).
a
ng/g lipid 3.66
ng/g lipid 3.11
No. of mothers
Reference
Noren et al. (1996) 40
Noren et al. (1996) 102
Reference
650
5 1 19 87 116 13 3 5 26 51
600
1990
Total PCBs
67
25 112 146 13
7
CB-105 CB-114 CB-118 CB-138 CB-153 CB-156 CB-157 CB-167 CB-170/190 CB-180
1988/1989
1984/1985
8 1 24 108 124 12 2 4 23 53
Year
Table 1 (Continued)
pg/g lipid 286 28
Lunden and Noren (1998) 60
ng/g lipid 0.50
Lunden and Noren (1998) 60
ng/g lipid 2.46
Noren et al. (1996) 40
410
4 1 16 74 106 9 2 4 24 48
1991
pg/g lipid 315 30
Lunden and Noren (1998) 40
ng/g lipid 0.48
Lunden and Noren (1998) 40
ng/g lipid 1.57
Noren et al. (1996) 20
380
3 1 15 62 96 10 2 3 20 40
1992
ng/g lipid 2.15
Meironyte et al. (1999) 20
416
5 0 16 72 93 13 2 3 22 46
1994
ng/g lipid 3.11
Meironyte et al. (1999) 20
367
13 65 83 12 2 1 19 41
4
1996
pg/g lipid 194 23
20
Present
ng/g lipid 4.01
Meironyte et al. (1999) 40
324
13 57 73 8 2 2 16 37
4
1997
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123 1115
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K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
1978; Noren, 1983b; Noren, 1988; Noren and Lunden, 1991; Noren et al., 1996; Lunden and Noren, 1998; Meironyte et al., 1999) as well as results from recently sampled milk and reanalysed samples for retrospective studies of compounds not previously determined. The study summarises the temporary changes in the levels of PCBs, PCNs, PCDDs, PCDFs, DDT, DDE, hexachlorobenzene, methylsulfonyl metabolites of PCBs and DDE and PBDEs in the perspective of the past 20± 30 yr. Dieldrin, a-hexachlorocyclohexane (a-HCH), b-hexachlorocyclohexane (b-HCH), oxychlordane, trans-nonachlor and pentachlorophenol were investigated in a shorter period, 13±17 yr. The compiled results are shown in Table 1.
rate of decline to half of the concentration, tdec 1=2 , was calculated to be 6 yr (Fig. 2; Table 2). HCB has been used as a fungicide and in certain industrial processes, e.g., aluminium melting, graphite electrodes, rubber and dye manufacture. The fungicidal use of HCB was withdrawn in 1980 and also its industrial use has been replaced (Oberg, 1996). HCB is also formed as a byproduct in chemical processes. Polychlorinated biphenyls (PCBs): An increase in PCB levels was indicated in the sixties and a decline in
3.1. Decreasing levels Due to voluntary stop in usage and authority measures taken to reduce the environmental pollution, the levels of organochlorine compounds have decreased in human milk. For most of the reported compounds the course of decline apply to a ®rst order rate expression (Figs. 1±3; Table 2). Pesticides: The most consistent decline in the levels is noticed for p, p0 -DDT and p, p0 -DDE. The level of p, p0 DDT in 1997 was only 1% of the level in 1967 and tdec 1=2 was calculated to be 4 yr. The decrease of its metabolite p, p0 -DDE was not obvious until after 1972 and the time for decrease to half of the concentration is longer than for DDT, tdec 1=2 was calculated to be 6 yr. In 1997 the concentration of p, p0 -DDE was 5% of that in 1972. The concentration of its metabolite, 3-methylsulfonyl-p, p0 -DDE (3-MeSO2 ±DDE), has decreased in parallel to that of DDE (Noren et al., 1996) (Fig. 1; Table 2). In Sweden, the use of several organochlorine pesticides (DDT, aldrin, dieldrin, chlordane) was restricted or prohibited in 1970 (Regulation on certain active substances, 1993). However, the application of DDT as a moth-proo®ng agent in Swedish homes had ceased already in the sixties. In 1970 the use of DDT was prohibited with the exemption for treatment of conifer plants. In 1975 the substance was totally banned (Regulation on certain active substances, 1993). After ceased usage of DDT the levels in breast milk declined rapidly. The levels of dieldrin also declined by a tdec 1=2 of 6 yr. The concentration of dieldrin in 1985 was 13% of that in 1967. The concentrations of a-HCH, b-HCH, oxychlordane, trans-nonachlor and pentachlorophenol also decreased (Table 1). However, due to the short time range studied (from 1972 to 1985 or 1989) the time for decrease of these pesticides to half of the levels were not calculated. The concentrations of HCB in breast milk varied during the 1970s but a manifest decline in the average levels is seen from 1974 (Table 1). The average concentration of HCB in 1997 was 5% of that in 1974 and the
Fig. 1. Concentrations and time related trends p, p0 -DDT, p, p0 -DDE, MeSO2 ±DDE and dieldrin in human milk expressed as exponential curves.
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
Fig. 2. Concentrations and time related trends of HCB, total PCBs, MeSO2 ±PCBs, CB-153, CB-138 and CB-118 in human milk expressed as exponential curves.
the levels was obvious from 1972. The level of total PCBs in 1997 was about 30% of that in 1972. Total PCBs refer to determination of the concentrations by comparison to the PCB product Clophen A50 using a packed column in GC analysis (Table 1). The tdec 1=2 of total PCBs was calculated to be 14 yr. The congener speci®c analysis of PCBs indicated some differences in elimination rates of certain congeners. The tdec 1=2 of the most stable congener, 2,20 ,4,40 ,5,50 -hexachlorobiphenyl (CB-153), was 17 yr and that of 2,20 ,3,4,40 ,5-hexachlorobiphenyl (CB-138) was 14 yr, while tdec 1=2 of 2,30 ,4,40 ,5-pentachlorobiphenyl (CB-118) was 11 yr (Table 2). The PCB congeners 2,20 ,4,
1117
Fig. 3. Concentrations and time related trends of PCNs, PCDDs, PCDFs and TEQs (sum of PCDDs, PCDFs, PCBs) in human milk expressed as exponential curves.
40 -tetrachlorobiphenyl (CB-47) and 20 ,3,30 ,4,5-pentachlorobiphenyl (CB-122) were not found in the samples (detection limit 1 pg/g lipids). The concentrations of methylsulfonyl metabolites of PCBs (MeSO2 ±PCBs) have decreased by a tdec 1=2 of 9 yr (Table 2; Fig. 2). The use of PCBs was restricted in 1972 and only allowed in closed system (capacitors and transformers). The remaining PCBs in closed systems were to be re placed by 1995 (Oberg, 1996, Swedish Code of Statutes., 1988). The decomposition of the very stable PCBs in the environment is a slow process. Consequently, PCBs are
1118
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
Table 2 Changes in the levels of organohalogen contaminants in human milk, given as the time to halve the concentration (tdec 1=2 ) or the time to double the concentration (tinc 2 ) (concentrations were calculated on the lipid weight basis) Compound 0
p, p -DDT p, p0 -DDE MeSO2 ±DDE HCB Dieldrin PCBs CB-118 CB-138 CB-153 MeSO2 ±PCBs PCNs PCDDs PCDFs TEQ (PCDDs/PCDFs/PCBs) PBDEs
Time range for studied curve (yr) 1967±1997 1972±1997 1972±1992 1974±1997 1967±1985 1972±1997 1972±1997 1972±1997 1972±1997 1972±1992 1972±1992 1972±1997 1972±1997 1992±1997 1972±1997
still circulating in the environment and the exposure will continue for a long time. Polychlorinated naphthalenes (PCNs): As other organochlorine compounds, the levels of PCNs in human milk (Lunden and Noren, 1998) were higher in the early 1970s and decreased during the period studied. In 1992 the sum of PCN congeners was 16% of the level in 1972 (Lunden and Noren, 1998) and the tdec 1=2 was calculated to be 8 yr. The applications of PCNs were similar to that of PCBs, though PCNs were also used for impregnation of wood. The documentation of usage of PCNs in Sweden is scarce. Most likely, PCNs have been of minor usage in Sweden. The contribution from imported goods treated with PCNs is not known. However, PCNs and PCBs have been found in capacitors and wires (Weistrand et al., 1992) and leakage from such goods may continue for a long time though the production of PCNs has ceased. For PCNs no restrictions are applied in Sweden or elsewhere (Hayward, 1998). Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs): A decline in the levels of PCDDs and PCDFs is seen from 1972. In all samples octachlorodibenzo-p-dioxin (OCDD) is by far the most predominant dioxin congener. Compared to the other dibenzo-p-dioxins this compound is of minor toxic relevance. Among the dibenzofurans 2,3,4,7, 8-PeCDF occurs at the highest levels and this compound is considered of high toxic potency. The sum of PCDDs and of PCDFs in 1997 was 24% and 17%, respectively, of the levels in 1972. The occurrence of these compounds in environment and humans is of great concern because of their high toxic responses, especially that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Measures have been
tdec 1=2 , )years; tinc2 , +years )4 )6 )6 )6 )6 )14 )11 )14 )17 )9 )8 )15 )11 )15 +5
R2 0.987 0.986 0.978 0.956 0.984 0.977 0.963 0.941 0.934 0.871 0.969 0.837 0.873 0.902 0.950
taken in order to reduced the formation of such compounds. Toxic equivalency factors (TEQs): Based on similar responses in in vivo and in vitro studies the toxicity of certain organochlorine compounds has been determined relative to that of TCDD. The obtained toxic equivalency factors (TEFs) are used to calculate toxic equivalent (TEQ) concentrations on the assumption that the toxic eects are additive. In the present survey the recently established international TEFs (WHO±TEFs) for PCDDs, PCDFs and PCBs (van den Berg et al., 1999) were used to calculate the TEQs in human milk (Table 3). Previously, several TEF schemes were proposed and consequently the TEQs in the present report are not consistent with the previously reported TEQs in milk from the Stockholm region (Lunden and Noren, 1998; Noren and Lunden, 1991). Using the WHO±TEFs the main contribution to TEQs in breast milk was from 3,30 ,4,40 ,5-PeCB (CB126), followed by 2,3,4,7,8-PeCDF and 1,2,3,7, 8-PeCDD. In 1997 the total TEQs was 28% of that in 1972. The tdec 1=2 was calculated to be 15 yr (Table 2; Fig. 3). 3.2. Increasing levels Polybrominated diphenyl ethers (PBDEs): In contrast to organochlorine compounds, the concentration of PBDEs in human milk have increased continuously since 1972. For the ®rst time the start of a contamination is demonstrated in breast milk and the levels show the coarse of an exponential increase from 1972 to 1997. In all time periods, 2,20 ,4,40 -tetraBDE was the predominant congener (Meironyte et al., 1999). Using the above equation for the rate of increase, it became evident that
CB-81 CB-77 CB-126 CB-169
No. of mothers
Non-ortho-PCBs
PCDFs 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF OCDF Sum PCDFs
PCDDs 2,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD Sum PCDDs
TEF 0.0001 0.0001 0.1 0.01
0.1 0.05 0.5 0.1 0.1 0.1 0.1 0.01 0.01 0.0001
TEF 1 1 0.1 0.1 0.1 0.01 0.0001
na 0.0076 29.8 0.67
195
0.8b 0.07 0.0005 9.67
1.4b 0.2 0.0004 16.40
na 0.0041 25.3 0.74
102
0.0005 8.08
0.8b 0.08
7
0.2
3a 0.69 0.02 9.71
1 5
na 0.0029 16.6 0.65
na 0.0035 10.2 0.43
TEQ pg/g lipids
431
8.5
14.5
204
0.3
3.1a 0.7 0.03 12.83
3 6
0.3
4a 0.96 0.04 17
4.2 1 1.6 0.06 23.86 0.3 0.1 21.5 1.3 1.1 0.5 0 0.5 0.02 0.0004 25.32
5 7
TEQ pg/lipids
na 0.0027 9.8 0.47
140
0.0002 9.48
0.7b 0.08
8.5
0.2
3.8a 0.57 0.03 14.4
3 15
140
na 0.0026 11.7 0.59
60
7 0.3 0.4 0.2 0 0.06 <0.01 <0.0004 8.16
0.2
2.7 0.6 0.44 0.03 10.77
3 4
60
na 0.002 8.6 0.41
60
5.5 0.3 0.3 0.2 0 0.05 <0.01 0.0003 6.45
0.1
2 0.5 0.35 0.02 8.87
2 4
60
Lunden and Noren (1998)
Lunden and Noren (1998)
Noren (1988), Noren et al. (1990), Lunden and Noren (1998), (1993)
Noren (1988), Noren etal. (1990), Lunden and Noren (1998)
Noren (1988), Noren et al. (1990), Lunden and Noren (1998) 340
Noren (1988), Noren et al. (1990), Lunden and Noren (1998) 245 102
1991
1990
1988/89
1984/85
1980
1976
5 12
Reference
No. of mothers
1972 Noren (1988), Noren et al. (1990), Lunden and Noren (1998) 75
Year
Table 3 Toxic equivalent (TEQ) concentrations of PCDDs, PCDFs and PCBs in human milk (na not analysed)
na 0.0024 10.4 0.56
40
7 0.3 0.3 0.1 0 0.07 <0.01 <0.0004 7.97
0.2
2.7 0.7 0.4 0.02 12.82
3 6
40
Lunden and Noren (1998)
1992
na 0.0016 7.6 0.39
20
0 0.05 <0.01 <0.0004 6.25
5.5 0.4 0.3
0
2.1 <0.5 0.3 0.01 8.41
2 4
20
Present
1997
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123 1119
b
a
Sum of HxCDDs. Sum of HxCDFs.
Total Sum TEQs
CB-105 CB-114 CB-118 CB-123 CB-156 CB-157 CB-167 CB-189 Sum mono-ortho-PCBs
No. of mothers
Mono-ortho-PCB
Sum non-ortho-PCBs
Year
Table 3 (Continued)
0.0001 0.0005 0.0001 0.0001 0.0005 0.0005 0.00001 0.0001
TEF
100
1.5 0.5 6 na 10 2 0.11 na 20.11
135
30.48
1972
77
1.6 0.5 4.6 na 9.5 1.5 0.04 na 17.74
153
26.04
1976
102
10.63
1984/85
52
0.8 0.5 3.1 na 6.5 1 0.03 na 11.93 39
0.8 0.5 2.4 na 6 1 0.04 na 10.74
TEQ pg/g lipids
431
17.25
1980
44
0.7 na 2.5 na 6.5 na na na 9.7
120
10.27
1988/89
42
0.5 0.5 1.9 na 6.5 1.5 0.05 na 10.95
60
12.29
1990
32
0.4 0.5 1.6 na 4.5 1 0.04 na 8.04
60
9.01
1991
40
0.3 0.5 1.5 na 5 1 0.03 na 8.33
40
10.96
1992
28
0.4 0 1.3 na 3 1 0 na 5.7
20
7.99
1997
1120 K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
the sum of PBDE congeners (2,4,40 -triBDE, 2,20 ,4,40 tetraBDE, 2,30 ,4,40 -tetraBDE, 2,20 ,4,40 6-pentaBDE, 2,20 ,4,40 ,5-pentaBDE, 2,20 ,3,4,40 -pentaBDE, 2,20 ,4,40 , 5,60 -hexaBDE, 2,20 ,4,40 ,5,50 -hexaBDE) was doubled (tinc 2 ) in 5 yr periods (Table 2; Fig. 4). In 1997 the levels reached a concentration of 4 ng/g lipid (Meironyte et al., 1999). PBDEs have not been produced in Sweden. However, they are imported for ¯ame retarding applications and in components and goods containing ¯ame retardants (Risk Assessment of Polybrominated Diphenyl Ethers, 1994). No restrictions are applied to the use of PBDFs in Sweden or elsewhere. 3.3. Distribution of contaminants The distribution of the contaminants calculated as percent of the sum of organohalogen compounds has changed during the time course studied. In 1972, p, p0 -DDE was the predominant compound, constituting 57% of the total of 4410 ng organohalogen compounds per gram milk lipids. In 1997 the amount of p, p0 -DDE had decreased to 27% of the total 483 ng/g lipids, and PCBs constituted the major part, 67% of the total (Fig. 5). The amount of PBDEs counted for 1% of the total in 1997.
1121
3.4. Other studies Other Swedish investigations have reported decreasing levels of organochlorine contaminants in milk from mothers living in Uppsala (Vaz et al., 1993; Atuma et al., 1998) and Sundsvall (Atuma et al., 1998). The studies covered the periods 1981±1990 and 1986±1994, respectively. Besides Sweden, a decrease in the levels of organochlorine pesticides and PCBs has been shown in human milk from, e.g., Poland (Sikorski et al., 1990), Norway (Johansen et al., 1994; Becher et al., 1995), Germany (F urst et al., 1994; Schade and Heinzow, 1998) and Canada (Craan and Haines, 1998). In the Nordic countries, the concentrations of organochlorine compounds are quite similar, while the levels of DDT were higher in Poland. The levels of PCBs were reported to be somewhat higher in Germany (Schade and Heinzow, 1998) and The Netherlands (Tuinstra et al., 1994) but lower in Canada (Craan and Haines, 1998). Much higher levels of DDT have been reported from regions with special pest problems. The sum of DDT compounds in breast milk was in India 6000 ng/g lipids (Jani et al., 1988), in Kwazulu 15 830 ng/g lipids (Bouwman et al., 1990) and in Zimbabwe 25 259 ng/g lipids (Chikuni et al., 1997). The levels of PCDDs and PCDFs are similar in Sweden, Norway, Finland, Estonia (Mussalo-Rauhamma and Lindstr om, 1995) and Lithuania (Becher et al., 1995). Much higher levels of TCDD (120 pg/g lipids) have been measured in breast milk from women living in agricultural regions of Kazakstan (Hooper et al., 1998). The Aral region is also highly contaminated with pesticides, indicating a pollution of great concern (Jensen et al., 1997). 4. Conclusions
Fig. 4. Concentrations an time related trends of PBDEs in human milk expressed as an exponential curve.
Fig. 5. Distribution of organohalogenated contaminants in human milk from 1972 to 1997.
The levels in milk re¯ect the mothersÕ exposure during their reached life time and the general pollution during that time. The decrease in the levels of pesticides and compounds originating from industrial usage con®rms the positive eects of restrictions and prohibitions applied to the usage of the compounds and other measures taken to minimize the pollution. However, the low rate of decrease in the levels of PCBs and dioxins indicate a prolonged exposure by these compounds that may be of concern also in coming decades. The current status, concerning the levels of organochlorine compounds in Swedish mothers and breast fed infants is much better than 20±30 years ago. An infantÕs exposure to the sum of organochlorine compounds in 1997 is estimated to 1/10 of that in 1972. At the same time the exposure to PBDEs has increased about 60 times. The exponential increase of PBDEs in breast milk is alarming and calls for measures to stop the exposure to PBDEs. Since also these
1122
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
environmental pollutants are or may become globally spread the consequences are of international concern. The present study shows that monitoring of breast milk serves an important sentinel function in detecting the occurrence and exposure of widespread toxic contaminants at an early stage and provides possibility to take measures before adverse health eects appear. Acknowledgements We gratefully acknowledge the personnel at the MotherÕs Milk Centre in Stockholm for collecting the samples. Part of this study was supported by grants from the Swedish Environmental Protection Agency, Lithuanian Ministry of Education and Science and Karolinska Institutet. References Blomkvist, G., 1981. Polybrominated aromatic Andersson, O., pollutants found in ®sh in Sweden. Chemosphere 10, 1051± 1060. Atuma, S.S., Hansson, L., Johansson, H., Slorach, S., Wit, C.A., Lindstr om, G., 1998. Organochlorine pesticides, polychlorinated biphenyls and dioxins in human milk from Swedish mothers. Food. Addit. Contam. 15, 142±150. Ballschmiter, K., Mennel, A., Buyten, J., 1993. Long chain alkyl-polysiloxanes as non-polar stationary phases in capillary gas chromatography. Fresenius J. Anal. Chem. 346, 396±402. Becher, G., Skaare, J.U., Polder, A., Sletten, B., Rossland, O.J., Hansen, H.K., Ptashekas, J., 1995. PCDDs, PCDFs and PCBs in human milk from dierent parts of Norway and Lithuania. J. Tox. Environ. Health 46, 133±148. Bouwman, H., Reinecke, A.J., Cooppan, R.M., Becker, P.J., 1990. Factors aecting levels of DDT and metabolites in human breast milk from Kwazulu. J. Tox. Environ. Health 31, 93±115. Chikuni, O., Nhachi, C.F., Nyazema, N.Z., Polder, A., Nafstad, I., Skaare, J.U., 1997. Assessment of environmental pollution by PCBs, DDT and its metabolites using human milk of mothers in Zimbabwe. Sci. Tot. Environ. 199, 183±190. Craan, A.G., Haines, D.A., 1998. Decrease in levels of DDT, DDE, dieldrin, heptachlor epoxide, oxychlordan, transnonachlor, b-HCH, HCB, PCBs, 1967±1992 or 1975±1992. Arch. Environ. Contam. Toxicol. 35, 702±710. Darnerud, P.O., Atuma, S., Aune, M., Cnattingius, S., Wernroth, M.-L., Wicklund-Glynn, A., 1998. Polybrominated diphenyl ethers (PBDEs) in breast milk from primiparous women in Uppsala country, Sweden. In: 18th Symposium on Halogenated Environmental Organic Pollutants, Dioxin Õ98, Stockholm, Sweden. Organohalogen Compounds 35, 411±414. de Voogt, P., Brinkman, U.A.Th., 1989. Production, properties and usage of polychlorinated biphenyls. In: Kimbrough, R.D., Jensen, A.A. (Eds.), Topics in Envorinmental Health.
Vol. 4. Halogenated Biphenyls, Terphenyls, Naphtalenes, Dibenzodioxins And Related Products. Elsevier, Amsterdam, pp. 3±45. Environmental Health Criteria, 1994. 162: Brominated Diphenyl Ethers. World Health Organization, Geneva. F urst, P., F urst, C., Wilmers, K., 1994. Human milk as a bioindicator for body burden of PCDDs, PCDFs, organochlorine pesticides and PCBs. Environ. Health Perspect 102 (suppl 1), 187±193. Haglund, P.S., Zook, D.R., Buser, H.-R., Hu, J., 1997. Identi®cation and quanti®cation of polybrominated diphenyl ethers and methoxy-polybrominated diphenyl ethers in Baltic Biota. Environ. Sci. Technol. 31, 3281±3287. Hayward, D., 1998. Identi®cation of bioaccumulating polychlorinated naphthalenes and their toxicological signi®cance. Environ. Research A 76, 1±18. Hooper, K., Petreas, M.X., Chuvakova, T., Kazbekova, G., Druz, N., Seminova, G., Sharmanov, T., Hayward, D., Jhe, S., Visita, P., Winkler, J., McKinney, M., Wade, T.J., Grassman, J., Stephens, R.D., 1998. Analysis of breast milk to assess exposure to chlorinated contaminants in Kazakstan. Environ. Health Perspect. 106, 797±906. Jani, J.P., Patel, J.S., Shah, M.P., Gupta, S.K., Kashyap, S.K., 1988. Levels of organochlorine pesticides in human milk in Ahmedabad, India. Int. Arch. Environ. Health 60, 111±113. Jansson, B., Asplund, L., Olsson,M., 1987. Brominated ¯ame retardants ± ubiquitous environmental pollutants? Chemosphere 16, 2343±2349. Jensen, S., Mazhitova, Z., Zetterstr om, R., 1997. Environmental pollution and child health in Aral Sea region in Kazakstan. Sci. Tot. Environ. 206, 187±193. Johansen, H.R., Becher, G., Polder, A., Skaare, J.U., 1994. Congener-speci®c determination of polychlorinated biphenyls and organochlorine pesticides in human milk from Norwegian mothers living in Oslo. J. Tox. Environ. Health 42, 157±171. 1997. New Klasson-Wehler, E., Hovander, L., Bergman, A., organohalogens in human plasma ± identi®cation and quanti®cation. In: 17th Symposium on Halogenated Environmental Organic Pollutants, DioxinÕ97. Organohalogen Compounds 33, 420±425. Noren, K., 1998. Polychlorinated naphthalenes and Lunden, A., other organochlorine contaminants in Swedish human milk, 1972±1992. Arch. Environ. Contam. Toxicol. 34, 414±423. Noren, K., 1999. Polybrominated Meironyte, D., Bergman, A., diphenyl ethers in Swedish human milk. A time related trend study, 1972±1997, J. Toxicol. Environ. Health Part A 62, 101±118. Mussalo-Rauhamaa, H., Lindstr om, G., 1995. PCDD and PCDF levels in human milk in Estonia and certain Nordic countries. Organohalogen Compounds 26, 245±246. Noren, K., 1983a. Some aspects of the determination of organochlorine contaminants in human milk. Arch. Environm. Contam. Toxicol. 12, 277±283. Noren, K., 1983b. Organochlorine contaminants in Swedish human milk from the Stockholm region. Acta Paediatr. Scand. 72, 259±264. Noren, K., 1988. Changes in the levels of organochlorine pesticides, polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in human milk from Stockholm, 1972±1985. Chemosphere 7, 39±49.
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123 1991. Trend studies of polychlorinated Noren, K., Lunden, A., biphenyls, dibenzo-p-dioxins and dibenzofurans in human milk. Chemosphere 23, 1895±1901. Pettersson, E., Bergman, A., 1996. Noren, K., Lunden, A., Methylsulfonyl metabolites of PCBs and DDE in human milk Sweden, 1972±1992. Environ. Health Perspect 104, 766±772. Sj 1990. Noren, K., Lunden, A., ovall, J., Bergman, A., Coplanar polychlorinated biphenyls in Swedish human milk. Chemosphere 20, 935±941. Noren, K., Sj ovall, J., 1987. Analysis of organochlorine pesticides, polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in human milk by extraction with the lipophilic gel Lipidex 5000. J. Chromatogr. Biomed. Appl. 422, 103±115. Oberg, T., 1996. Replacement of PCBs (polychlorinated biphenyls) and HCB (hexachlorobenzene) ± in Swedish experience. In: Alternatives to Persistent Organic Pollutants. KEMI (Swedish National Chemicals Inspectorate) 4/96, 133±151. Population statistics, 1996. Part 4: Vital statistics, Statistics Sweden. Rappe, C., 1994. Dioxins, patterns and source identi®cation. FreseniusÕ J. Anal. Chem. 348, 63±75. Regulation on certain active substances (pesticides), 1993. KIFS 1993:5, Swedish National Chemical Inspectorate. Risk Assessment of Polybrominated Diphenyl Ethers, 1994. The Swedish National Chemicals Inspectorate, Report 9. Schade, G., Heinzow, B., 1998. Organochlorine pesticides and polychlorinated biphenyls in human milk of mothers living in northern Germany: current extent of contamination, time trend from 1986 to 1997 and factor that in¯uence the levels of contamination. Sci. Total Environ. 215, 31±39. Sellstr om, U., Jansson, B., Kirkegaard, A., de Wit, C., 1993. Polybrominated diphenyl ethers (PBDE) in biological samples from the Swedish environment. Chemosphere 26, 1703± 1718. Sikorski, R., Paszkowski, T., Radomanski, T., Niewiadowska, A., Semeniuk, S., 1990. Human colostrum as a source of organohalogen xenobiotics for a breast-fed neonate. Repr. Toxicol. 4, 17±20.
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Sj odin, A., Hagmar, L., Klasson-Wehler, E., Kronholm-Diab, 1999. Polybrominated K., Jakobsson, E., Bergman, A., diphenyl ethers (PBDEs) in blood from Swedish workers. Environ. Health Perspect 107, 643±648. Swedish Code of Statutes, SFS 1988:1083. Tuinstra, L.G.M.Th., Huisman, M., Boersma, E.R., 1994. The Dutch PCB/dioxin study. Contents of dioxins planar and other PCBs in human milk from Rotterdam and Groningen area. Chemosphere 29, 2267±2277. van den Berg, M., Birnbaum, L., Bosveld, A.T.C., Brunstr om, B., Cook, P., Feeley, M., Giesy, J.P., Hanberg, A., Hasegawa, R., Kennedy, S.W., Kubiak, T., Larsen, J.C., van Leeuwen, F.X.R., Liem, A.K.D., Nolt, C., Peterson, R.E., Poellinger, L., Safe, S., Schrenk, D., Tillitt, D., Tysklind, M., Younes, M., Waern, F., Zacharewski, T., 1998. Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife. Environ. Health Perspect 106, 775±792. Vaz, R., Slorach, S., Hovander, Y., 1993. Organochlorine contaminants in Swedish human milk: studies conducted at the National food Administration, 1981±1990. Food Add. Contam. 10, 407±418. Noren, K., 1992. Leakage of Weistrand, C., Lunden, A., polychlorinated biphenyls and naphthalenes from electronic equipment in a laboratory. Chemosphere 24, 1197± 1207. Weistrand, C., Noren, K., 1998. Polychlorinated naphthalenes and other organochlorine contaminants in human adipose tissue. J. Toxicol. Environm. Health 53, 293±311. , G., Noren, K., 1970. Determination of organochlorine West oo pesticides and polychlorinated biphenyls in animal foods. Acta Chem. Scand. 24, 1639±1644. , G., Noren, K., 1972. Levels of organochlorine West oo pesticides and polychlorinated biphenyls in Swedish human milk. V ar F oda 24, 41±54. , G., Noren, K., 1978. Organochlorine contaminants in West oo human milk, Stockholm, 1967±1977. Ambio 7, 62±64. , G., Noren, K., Andersson, M., 1970. Levels of West oo organochlorine pesticides and polychlorinated biphenyls in margarine, vegetable olis and some foods of animal origin. V ar F oda 22, 9±31.
Certain organochlorine and organobromine contaminants in Swedish human milk in perspective of past 20±30 years Koidu Noren *, Daiva Meironyte Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden
Abstract The investigations of organochlorine compounds in breast milk from women living in the Stockholm region started in 1967. The present study summarises the investigations of polychlorinated biphenyls (PCBs), naphthalenes (PCNs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), polybrominated diphenyl ethers (PBDEs) and pesticides (DDT, DDE, hexachlorobenzene, dieldrin) as well as methylsulfonyl metabolites of PCBs and DDE in human milk sampled during dierent periods up to 1997. During the course of 20±30 yr the levels of organochlorine compounds in human milk have decreased to various extent. A decrease to the half of the original concentration was attained in the range of 4±17 yr periods. On the contrary to the organochlorine compounds, the concentrations of PBDEs have increased during the period 1972±1997, indicating a doubling of the levels by 5 yr. The levels re¯ect the environmental contamination and background levels in the population. The accumulation and ongoing increase in the levels of PBDEs calls for immediate measures to stop the environmental pollution and human exposure to PBDEs. Ó 2000 Elsevier Science Ltd. All rights reserved. Keywords: PCB; PCDD; PCDF; Pesticides; Methylsulfonyl metabolites; PBDE; Flame retardant
1. Introduction The production of most of the organochlorine compounds, which are found as pollutants in our environment, started in the 1930s. The found insecticidal properties of DDT led to development of a number of organochlorine pesticides, e.g., aldrin, dieldrin, chlordane, heptachlor, lindane, pentachlorophenol. Other organochlorine products became of industrial importance due to their stability and isolating properties. The most widely used of such products were polychlorinated biphenyls (PCBs), but also polychlorinated naphthalenes (PCNs) were manufactured for industrial applications, e.g., capacitor dielectrics, cutting oils, plasticisers in dyes and sealants, wire and cable coatings (de Voogt and Brinkman, 1989; Hayward, 1998). PCNs were introduced in 1909 and became of revived importance in * Corresponding author. Tel.: +46-8-728-6400; fax: +46-830-44-52.
1930s (Hayward, 1998). The production of PCNs is not well documented but the amount was less than that of PCBs (de Voogt and Brinkman, 1989). The extensive use of organochlorine compounds has released an unprecedented number of toxic substances into the environment. From the 1970s on, many countries have applied prohibitions on the use of speci®c organochlorine compounds. Another group of pollutants, the polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), are found as by-products in other chemicals and formed in various combustion processes. Identi®ed sources are, e.g., waste incineration, iron and steel production, pulp bleaching and chloralkali industry (Rappe, 1994). Measures have been taken in order to reduced the formation of such compounds. Contrary to the organochlorine compounds, the use of polybrominated diphenyl ethers (PBDEs) increased in the European Economic Community (EEC) during 1980s (Environmental Health Criteria, 1994). These products have a wide application as ¯ame retardants,
0045-6535/00/$ - see front matter Ó 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 0 4 5 - 6 5 3 5 ( 9 9 ) 0 0 3 6 0 - 4
1112
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
especially in polymers used in electronics (TVs, computers), and textiles (Environmental Health Criteria, 1994; Risk Assessment of Polybrominated Diphenyl Ethers, 1994). PBDEs are mixed into the material they are used in. Since PBDEs are not chemically bound they may migrate from the material and PBDEs are now widely dispersed in the environment. Like the organochlorine compounds, PBDEs have been found in, e.g., ®sh (Andersson and Blomkvist, 1981; Jansson et al., 1987; Sellstr om et al., 1993) and mammals including humans (Haglund et al., 1997; Klasson-Wehler et al., 1997; Darnerud et al., 1998; Meironyte et al., 1999; Sj odin et al., 1999). Persistent lipophilic organohalogen environmental contaminants accumulate in the human body. The elimination of such compounds and their lipophilic metabolites from body fat is very low. Due to the relatively high fat content of breast milk, the lipophilic compounds are transferred to the milk. The levels in milk are strongly correlated to the fat content of the milk (Noren, 1983a, 1988) and re¯ect the accumulated levels in the adipose tissue. Accordingly, milk constitutes a suitable matrix for studies of long term exposure to organohalogen pollutants and for studies of time related trends in environmental contamination. The present survey of organohalogen compounds in human milk from the Stockholm region includes both previously reported data and recent results. For most of the compounds the levels cover the period from 1972 to 1992 or 1997. However, the ®rst analyses of DDT, DDE, dieldrin and PCBs were performed in 1967. The early investigations of pesticides and PCBs have been completed by congener speci®c analysis of PCBs, PCDDs, PCDFs, PCNs, methylsulfonyl metabolites of DDE and PCBs and PBDEs.
2. Materials and methods The milk was obtained from healthy native Swedish mothers living in the Stockholm region. The ®rst samples were collected in 1967 but only from 1972 on, milk was banked for coming reanalysis. From 1986 on, the donors were non-smokers and the milk was collected during the ®rst three months after delivery. Equal amounts of milk from individual mothers were mixed to constitute pooled samples. In order to get comparable samples, the composition of pools was kept as equal to that of the early sampled milk as possible. In the pools 55±75% of the milk was from mothers nursing their ®rst infant. The average age of the mothers was 27±28 yr in the period 1972±1985, 29±30 yr in 1988±1994 and 30±31 yr in 1996±1997. The age of the mothers in 1967 and 1969 is not documented. The increase in age is consistent with the general increase of the age of the mothers giving
birth in Sweden (Population statistics, 1996). The milk was stored at )20°C. The details of the analytical procedures for organochlorine compounds have been described previously and Noren, 1970; Noren and (Noren, 1983a; West oo Sj ovall, 1987; Noren et al., 1996). Puri®cation and separation of compounds were made by chromatography on aluminium oxide, silica gel, activated charcoal and gel permeation chromatography. In the analysis of samples from 1994 to 1997, instead of activated charcoal the separation of planar compounds was performed by HPLC on a Cosmosil 5-PYE column (2-(1-pyrenyl)ethyldimethylsilylated silica gel: 250 ´ 4.6 mm, 0.5 lm particle size) from Nacalai Tesque (Kyoto, Japan) (as described by Weistrand and Noren, 1998). Identi®cations and quanti®cations were made by gas chromatography electron capture detection and gas chromatography/mass spectrometry using selected ion recording. Slight modi®cation of the method enabled the analysis of PBDEs (Meironyte et al., 1999). Total PCBs refer to determination of the concentrations by comparison to the PCB product Clophen A50 (Bayer, Leverkusen, Germany) using a packed column et al., in the analysis by gas chromatography (West oo and Noren, 1970; Noren, 1983a). By the 1970; West oo time when capillary columns and standards of individual PCB congeners became available, the concentrations of PCB were determined both as total PCBs using a packed column and as speci®c PCB congeners using a capillary column and 18 PCB congeners as standards for comparison (Noren et al., 1990; Lunden and Noren, 1998). Congener speci®c analyses were performed when reanalysing archived samples. The sum of PCB congeners was on an average 68% of the total PCBs. From 1994 on, only capillary columns were used and the total PCBs were calculated from the sum of PCB congeners on the above assumption. The changes in the levels of organohalogen compounds were examined for adaptation to a ®rst order rate expression: ÿdC=dt k C; which on integration yields: ln C0 =Ct k t, where C0 is the concentration at the ®rst investigation, Ct the concentration at the last investigation, k the constant and t is the time range of investigations. The rate of decrease is given as the time to halve the concentration, decline half-time, tdec 1=2 , the time increase to the double concentration as tinc 2 and correlation to the exponential curve as R2 . 3. Results and discussion The present report includes previously reported re et al., 1970; West and Noren, 1972, sults (West oo oo
ng/g lipid 7.98
ng/g lipid
ng/g lipid 9.24
Sum MeSO2 ±CBs
790
ng/g lipid 4.56
Noren et al. (1996) 199
65 780 880
ng/g lipid 29
and West oo Noren (1970) 431
ng/g lipid 1055 185 18 9 96 14 19 125 17d
Noren (1988) and Noren and Lunden (1991) 973
1980
84 910
ng/g lipid
ng/g lipid 1130 210 20 8 110 16 22 120
Noren and Lunden (1991) 805
1979
8 1 31 134 152 13 2 3
ng/g lipid
ng/g lipid 1270 270 22 8 120 16 21 120
Noren and Lunden (1991) 745
1978
16 1 46 177 197 19 3 4
ng/g lipid 22
and West oo Noren (1970) 156
ng/g lipid 1500 340 25 <8 130 16c 19c 110 36c
1500
Noren (1988) and Noren (1983b)
1976
No. of mothers
810
ng/g lipid
220
ng/g lipid 1800 470 38 <8 120
250
Noren (1983b)
1974
Noren et al. (1996) 153
600
ng/g lipid 34 4 11 15 1 60 190 215 20 4 11 41 88 1090
and Noren West oo (1970) 135
ng/g lipid 2420 710 49 7 280 19 20 120 30
227
Noren (1988)
1972
Noren et al. (1996) 75
Reference
CB-28e CB-52 CB-101 CB-105 CB-114 CB-118 CB-138 CB-153 CB-156 CB-157 CB-167 CB-170/190 CB-180 Total PCBs
No. of mothers
Reference
500
ng/g lipid 1700 1020 67b
ng/g lipid 2000 1300 76a
ng/g lipid
75
210
No. of mothers
ng/g lipid
and West oo Noren (1972)
Reference
p, p0 -DDE p, p0 -DDT Dieldrin a-HCH b-HCH Oxychlordane trans-Nonachlor HCB Pentachlorophenol
1968/1969
1967
and West oo Noren (1972)
Year
Table 1 Concentrations of organohalogen contaminants in Swedish human milk, 1967±1997
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123 1113
ng/g lipid 369 42
33
ng/g lipid 480 47
12 17 40
102
ng/g lipid 500 61 10 3 72 13 13 37 12
Noren (1988)
102
ng/g lipid 22
No. of mothers
p, p0 -DDE p, p0 -DDT Dieldrin a-HCH b-HCH Oxychlordane trans-Nonachlor HCB Pentachlorophenol
Reference
No. of mothers
PCBs CB-28 CN-52 CB-101
ng/g lipid 9
ng/g lipid 9 1 2
Lunden and Noren (1998) 60
Lunden and Noren (1998), present 40
et al. West oo (1970) 140
Lunden and Noren (1998) 120
1990
1988/1989
1984/1985
ng/g lipid 6 1 2
Lunden and Noren (1998) 60
27
ng/g lipid 255 36
Lunden and Noren (1998) 40
ng/g lipid 4 1 2
Lunden and Noren (1998) 40
31
ng/g lipid 227 22
Lunden and Noren (1998) 20
1992
pg/g lipid 825 132
Sum PCDDs Sum PCDFs
Noren (1988)
pg/g lipid 519 71
75
No. of mothers
Reference
Noren (1988) and et al. West oo (1970) 204
et al. West oo (1970)
Reference
Year
ng/g lipid 0.28
et al. West oo (1970) 78 ng/g lipid 1.73
1976
ng/g lipid 0.07
1991
1974
Sum PBDEs
et al. West oo (1970) 75 ng/g lipid 3.08
1972
No. of mothers
1968/1969
Meironyte et al. (1999) 78
1967
Meironyte et al. (1999) 75
Reference
Sum PCN
No. of mothers
Reference
Year
Table 1 (Continued)
ng/g lipid 5 0 2
20
Present
15
ng/g lipid 199 12
20
Present
1994
1978
ng/g lipid 3 1 1
20
Present
14
ng/g lip 164 14
20
Present
1996
1979
ng/g lipid 4 0 1
40
Present
12
ng/g lipid 129 14
40
Present
1997
pg/g lipid 448 40
Noren (1988) and et al. West oo (1970) 431
ng/g lipid 0.48
Meironyte et al. (1999) 116
et al. West oo (1970) 116 ng/g lipid 1.23
1980
1114 K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
Sum MeSO2 ±CBs
Present
ng/g lipid 1.21
140 pg/g lipid 373 36
ng/g lipid 0.72
Noren (1988)
102
pg/g lipid 349 37
No. of mothers
Sum PBDEs
Reference
No. of mothers
Sum PCDDs Sum PCDFs
b
pg/g lipid 429 31
Lunden and Noren (1998) 60
Meironyte et al. (1999) 20
Sum PCN
Meironyte et al. (1999) 102
ng/g lipid 0.71
ng/g lipid 0.89
No. of mothers
Reference
Lunden and Noren (1998) 60
510
Lunden and Noren (1998) 102
90 mothers. 45 mothers. c 245 mothers. d 340 mothers. e Numbering of PCBs according to Ballschmiter et al. (1993).
a
ng/g lipid 3.66
ng/g lipid 3.11
No. of mothers
Reference
Noren et al. (1996) 40
Noren et al. (1996) 102
Reference
650
5 1 19 87 116 13 3 5 26 51
600
1990
Total PCBs
67
25 112 146 13
7
CB-105 CB-114 CB-118 CB-138 CB-153 CB-156 CB-157 CB-167 CB-170/190 CB-180
1988/1989
1984/1985
8 1 24 108 124 12 2 4 23 53
Year
Table 1 (Continued)
pg/g lipid 286 28
Lunden and Noren (1998) 60
ng/g lipid 0.50
Lunden and Noren (1998) 60
ng/g lipid 2.46
Noren et al. (1996) 40
410
4 1 16 74 106 9 2 4 24 48
1991
pg/g lipid 315 30
Lunden and Noren (1998) 40
ng/g lipid 0.48
Lunden and Noren (1998) 40
ng/g lipid 1.57
Noren et al. (1996) 20
380
3 1 15 62 96 10 2 3 20 40
1992
ng/g lipid 2.15
Meironyte et al. (1999) 20
416
5 0 16 72 93 13 2 3 22 46
1994
ng/g lipid 3.11
Meironyte et al. (1999) 20
367
13 65 83 12 2 1 19 41
4
1996
pg/g lipid 194 23
20
Present
ng/g lipid 4.01
Meironyte et al. (1999) 40
324
13 57 73 8 2 2 16 37
4
1997
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123 1115
1116
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
1978; Noren, 1983b; Noren, 1988; Noren and Lunden, 1991; Noren et al., 1996; Lunden and Noren, 1998; Meironyte et al., 1999) as well as results from recently sampled milk and reanalysed samples for retrospective studies of compounds not previously determined. The study summarises the temporary changes in the levels of PCBs, PCNs, PCDDs, PCDFs, DDT, DDE, hexachlorobenzene, methylsulfonyl metabolites of PCBs and DDE and PBDEs in the perspective of the past 20± 30 yr. Dieldrin, a-hexachlorocyclohexane (a-HCH), b-hexachlorocyclohexane (b-HCH), oxychlordane, trans-nonachlor and pentachlorophenol were investigated in a shorter period, 13±17 yr. The compiled results are shown in Table 1.
rate of decline to half of the concentration, tdec 1=2 , was calculated to be 6 yr (Fig. 2; Table 2). HCB has been used as a fungicide and in certain industrial processes, e.g., aluminium melting, graphite electrodes, rubber and dye manufacture. The fungicidal use of HCB was withdrawn in 1980 and also its industrial use has been replaced (Oberg, 1996). HCB is also formed as a byproduct in chemical processes. Polychlorinated biphenyls (PCBs): An increase in PCB levels was indicated in the sixties and a decline in
3.1. Decreasing levels Due to voluntary stop in usage and authority measures taken to reduce the environmental pollution, the levels of organochlorine compounds have decreased in human milk. For most of the reported compounds the course of decline apply to a ®rst order rate expression (Figs. 1±3; Table 2). Pesticides: The most consistent decline in the levels is noticed for p, p0 -DDT and p, p0 -DDE. The level of p, p0 DDT in 1997 was only 1% of the level in 1967 and tdec 1=2 was calculated to be 4 yr. The decrease of its metabolite p, p0 -DDE was not obvious until after 1972 and the time for decrease to half of the concentration is longer than for DDT, tdec 1=2 was calculated to be 6 yr. In 1997 the concentration of p, p0 -DDE was 5% of that in 1972. The concentration of its metabolite, 3-methylsulfonyl-p, p0 -DDE (3-MeSO2 ±DDE), has decreased in parallel to that of DDE (Noren et al., 1996) (Fig. 1; Table 2). In Sweden, the use of several organochlorine pesticides (DDT, aldrin, dieldrin, chlordane) was restricted or prohibited in 1970 (Regulation on certain active substances, 1993). However, the application of DDT as a moth-proo®ng agent in Swedish homes had ceased already in the sixties. In 1970 the use of DDT was prohibited with the exemption for treatment of conifer plants. In 1975 the substance was totally banned (Regulation on certain active substances, 1993). After ceased usage of DDT the levels in breast milk declined rapidly. The levels of dieldrin also declined by a tdec 1=2 of 6 yr. The concentration of dieldrin in 1985 was 13% of that in 1967. The concentrations of a-HCH, b-HCH, oxychlordane, trans-nonachlor and pentachlorophenol also decreased (Table 1). However, due to the short time range studied (from 1972 to 1985 or 1989) the time for decrease of these pesticides to half of the levels were not calculated. The concentrations of HCB in breast milk varied during the 1970s but a manifest decline in the average levels is seen from 1974 (Table 1). The average concentration of HCB in 1997 was 5% of that in 1974 and the
Fig. 1. Concentrations and time related trends p, p0 -DDT, p, p0 -DDE, MeSO2 ±DDE and dieldrin in human milk expressed as exponential curves.
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
Fig. 2. Concentrations and time related trends of HCB, total PCBs, MeSO2 ±PCBs, CB-153, CB-138 and CB-118 in human milk expressed as exponential curves.
the levels was obvious from 1972. The level of total PCBs in 1997 was about 30% of that in 1972. Total PCBs refer to determination of the concentrations by comparison to the PCB product Clophen A50 using a packed column in GC analysis (Table 1). The tdec 1=2 of total PCBs was calculated to be 14 yr. The congener speci®c analysis of PCBs indicated some differences in elimination rates of certain congeners. The tdec 1=2 of the most stable congener, 2,20 ,4,40 ,5,50 -hexachlorobiphenyl (CB-153), was 17 yr and that of 2,20 ,3,4,40 ,5-hexachlorobiphenyl (CB-138) was 14 yr, while tdec 1=2 of 2,30 ,4,40 ,5-pentachlorobiphenyl (CB-118) was 11 yr (Table 2). The PCB congeners 2,20 ,4,
1117
Fig. 3. Concentrations and time related trends of PCNs, PCDDs, PCDFs and TEQs (sum of PCDDs, PCDFs, PCBs) in human milk expressed as exponential curves.
40 -tetrachlorobiphenyl (CB-47) and 20 ,3,30 ,4,5-pentachlorobiphenyl (CB-122) were not found in the samples (detection limit 1 pg/g lipids). The concentrations of methylsulfonyl metabolites of PCBs (MeSO2 ±PCBs) have decreased by a tdec 1=2 of 9 yr (Table 2; Fig. 2). The use of PCBs was restricted in 1972 and only allowed in closed system (capacitors and transformers). The remaining PCBs in closed systems were to be re placed by 1995 (Oberg, 1996, Swedish Code of Statutes., 1988). The decomposition of the very stable PCBs in the environment is a slow process. Consequently, PCBs are
1118
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
Table 2 Changes in the levels of organohalogen contaminants in human milk, given as the time to halve the concentration (tdec 1=2 ) or the time to double the concentration (tinc 2 ) (concentrations were calculated on the lipid weight basis) Compound 0
p, p -DDT p, p0 -DDE MeSO2 ±DDE HCB Dieldrin PCBs CB-118 CB-138 CB-153 MeSO2 ±PCBs PCNs PCDDs PCDFs TEQ (PCDDs/PCDFs/PCBs) PBDEs
Time range for studied curve (yr) 1967±1997 1972±1997 1972±1992 1974±1997 1967±1985 1972±1997 1972±1997 1972±1997 1972±1997 1972±1992 1972±1992 1972±1997 1972±1997 1992±1997 1972±1997
still circulating in the environment and the exposure will continue for a long time. Polychlorinated naphthalenes (PCNs): As other organochlorine compounds, the levels of PCNs in human milk (Lunden and Noren, 1998) were higher in the early 1970s and decreased during the period studied. In 1992 the sum of PCN congeners was 16% of the level in 1972 (Lunden and Noren, 1998) and the tdec 1=2 was calculated to be 8 yr. The applications of PCNs were similar to that of PCBs, though PCNs were also used for impregnation of wood. The documentation of usage of PCNs in Sweden is scarce. Most likely, PCNs have been of minor usage in Sweden. The contribution from imported goods treated with PCNs is not known. However, PCNs and PCBs have been found in capacitors and wires (Weistrand et al., 1992) and leakage from such goods may continue for a long time though the production of PCNs has ceased. For PCNs no restrictions are applied in Sweden or elsewhere (Hayward, 1998). Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs): A decline in the levels of PCDDs and PCDFs is seen from 1972. In all samples octachlorodibenzo-p-dioxin (OCDD) is by far the most predominant dioxin congener. Compared to the other dibenzo-p-dioxins this compound is of minor toxic relevance. Among the dibenzofurans 2,3,4,7, 8-PeCDF occurs at the highest levels and this compound is considered of high toxic potency. The sum of PCDDs and of PCDFs in 1997 was 24% and 17%, respectively, of the levels in 1972. The occurrence of these compounds in environment and humans is of great concern because of their high toxic responses, especially that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Measures have been
tdec 1=2 , )years; tinc2 , +years )4 )6 )6 )6 )6 )14 )11 )14 )17 )9 )8 )15 )11 )15 +5
R2 0.987 0.986 0.978 0.956 0.984 0.977 0.963 0.941 0.934 0.871 0.969 0.837 0.873 0.902 0.950
taken in order to reduced the formation of such compounds. Toxic equivalency factors (TEQs): Based on similar responses in in vivo and in vitro studies the toxicity of certain organochlorine compounds has been determined relative to that of TCDD. The obtained toxic equivalency factors (TEFs) are used to calculate toxic equivalent (TEQ) concentrations on the assumption that the toxic eects are additive. In the present survey the recently established international TEFs (WHO±TEFs) for PCDDs, PCDFs and PCBs (van den Berg et al., 1999) were used to calculate the TEQs in human milk (Table 3). Previously, several TEF schemes were proposed and consequently the TEQs in the present report are not consistent with the previously reported TEQs in milk from the Stockholm region (Lunden and Noren, 1998; Noren and Lunden, 1991). Using the WHO±TEFs the main contribution to TEQs in breast milk was from 3,30 ,4,40 ,5-PeCB (CB126), followed by 2,3,4,7,8-PeCDF and 1,2,3,7, 8-PeCDD. In 1997 the total TEQs was 28% of that in 1972. The tdec 1=2 was calculated to be 15 yr (Table 2; Fig. 3). 3.2. Increasing levels Polybrominated diphenyl ethers (PBDEs): In contrast to organochlorine compounds, the concentration of PBDEs in human milk have increased continuously since 1972. For the ®rst time the start of a contamination is demonstrated in breast milk and the levels show the coarse of an exponential increase from 1972 to 1997. In all time periods, 2,20 ,4,40 -tetraBDE was the predominant congener (Meironyte et al., 1999). Using the above equation for the rate of increase, it became evident that
CB-81 CB-77 CB-126 CB-169
No. of mothers
Non-ortho-PCBs
PCDFs 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF OCDF Sum PCDFs
PCDDs 2,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD Sum PCDDs
TEF 0.0001 0.0001 0.1 0.01
0.1 0.05 0.5 0.1 0.1 0.1 0.1 0.01 0.01 0.0001
TEF 1 1 0.1 0.1 0.1 0.01 0.0001
na 0.0076 29.8 0.67
195
0.8b 0.07 0.0005 9.67
1.4b 0.2 0.0004 16.40
na 0.0041 25.3 0.74
102
0.0005 8.08
0.8b 0.08
7
0.2
3a 0.69 0.02 9.71
1 5
na 0.0029 16.6 0.65
na 0.0035 10.2 0.43
TEQ pg/g lipids
431
8.5
14.5
204
0.3
3.1a 0.7 0.03 12.83
3 6
0.3
4a 0.96 0.04 17
4.2 1 1.6 0.06 23.86 0.3 0.1 21.5 1.3 1.1 0.5 0 0.5 0.02 0.0004 25.32
5 7
TEQ pg/lipids
na 0.0027 9.8 0.47
140
0.0002 9.48
0.7b 0.08
8.5
0.2
3.8a 0.57 0.03 14.4
3 15
140
na 0.0026 11.7 0.59
60
7 0.3 0.4 0.2 0 0.06 <0.01 <0.0004 8.16
0.2
2.7 0.6 0.44 0.03 10.77
3 4
60
na 0.002 8.6 0.41
60
5.5 0.3 0.3 0.2 0 0.05 <0.01 0.0003 6.45
0.1
2 0.5 0.35 0.02 8.87
2 4
60
Lunden and Noren (1998)
Lunden and Noren (1998)
Noren (1988), Noren et al. (1990), Lunden and Noren (1998), (1993)
Noren (1988), Noren etal. (1990), Lunden and Noren (1998)
Noren (1988), Noren et al. (1990), Lunden and Noren (1998) 340
Noren (1988), Noren et al. (1990), Lunden and Noren (1998) 245 102
1991
1990
1988/89
1984/85
1980
1976
5 12
Reference
No. of mothers
1972 Noren (1988), Noren et al. (1990), Lunden and Noren (1998) 75
Year
Table 3 Toxic equivalent (TEQ) concentrations of PCDDs, PCDFs and PCBs in human milk (na not analysed)
na 0.0024 10.4 0.56
40
7 0.3 0.3 0.1 0 0.07 <0.01 <0.0004 7.97
0.2
2.7 0.7 0.4 0.02 12.82
3 6
40
Lunden and Noren (1998)
1992
na 0.0016 7.6 0.39
20
0 0.05 <0.01 <0.0004 6.25
5.5 0.4 0.3
0
2.1 <0.5 0.3 0.01 8.41
2 4
20
Present
1997
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123 1119
b
a
Sum of HxCDDs. Sum of HxCDFs.
Total Sum TEQs
CB-105 CB-114 CB-118 CB-123 CB-156 CB-157 CB-167 CB-189 Sum mono-ortho-PCBs
No. of mothers
Mono-ortho-PCB
Sum non-ortho-PCBs
Year
Table 3 (Continued)
0.0001 0.0005 0.0001 0.0001 0.0005 0.0005 0.00001 0.0001
TEF
100
1.5 0.5 6 na 10 2 0.11 na 20.11
135
30.48
1972
77
1.6 0.5 4.6 na 9.5 1.5 0.04 na 17.74
153
26.04
1976
102
10.63
1984/85
52
0.8 0.5 3.1 na 6.5 1 0.03 na 11.93 39
0.8 0.5 2.4 na 6 1 0.04 na 10.74
TEQ pg/g lipids
431
17.25
1980
44
0.7 na 2.5 na 6.5 na na na 9.7
120
10.27
1988/89
42
0.5 0.5 1.9 na 6.5 1.5 0.05 na 10.95
60
12.29
1990
32
0.4 0.5 1.6 na 4.5 1 0.04 na 8.04
60
9.01
1991
40
0.3 0.5 1.5 na 5 1 0.03 na 8.33
40
10.96
1992
28
0.4 0 1.3 na 3 1 0 na 5.7
20
7.99
1997
1120 K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
the sum of PBDE congeners (2,4,40 -triBDE, 2,20 ,4,40 tetraBDE, 2,30 ,4,40 -tetraBDE, 2,20 ,4,40 6-pentaBDE, 2,20 ,4,40 ,5-pentaBDE, 2,20 ,3,4,40 -pentaBDE, 2,20 ,4,40 , 5,60 -hexaBDE, 2,20 ,4,40 ,5,50 -hexaBDE) was doubled (tinc 2 ) in 5 yr periods (Table 2; Fig. 4). In 1997 the levels reached a concentration of 4 ng/g lipid (Meironyte et al., 1999). PBDEs have not been produced in Sweden. However, they are imported for ¯ame retarding applications and in components and goods containing ¯ame retardants (Risk Assessment of Polybrominated Diphenyl Ethers, 1994). No restrictions are applied to the use of PBDFs in Sweden or elsewhere. 3.3. Distribution of contaminants The distribution of the contaminants calculated as percent of the sum of organohalogen compounds has changed during the time course studied. In 1972, p, p0 -DDE was the predominant compound, constituting 57% of the total of 4410 ng organohalogen compounds per gram milk lipids. In 1997 the amount of p, p0 -DDE had decreased to 27% of the total 483 ng/g lipids, and PCBs constituted the major part, 67% of the total (Fig. 5). The amount of PBDEs counted for 1% of the total in 1997.
1121
3.4. Other studies Other Swedish investigations have reported decreasing levels of organochlorine contaminants in milk from mothers living in Uppsala (Vaz et al., 1993; Atuma et al., 1998) and Sundsvall (Atuma et al., 1998). The studies covered the periods 1981±1990 and 1986±1994, respectively. Besides Sweden, a decrease in the levels of organochlorine pesticides and PCBs has been shown in human milk from, e.g., Poland (Sikorski et al., 1990), Norway (Johansen et al., 1994; Becher et al., 1995), Germany (F urst et al., 1994; Schade and Heinzow, 1998) and Canada (Craan and Haines, 1998). In the Nordic countries, the concentrations of organochlorine compounds are quite similar, while the levels of DDT were higher in Poland. The levels of PCBs were reported to be somewhat higher in Germany (Schade and Heinzow, 1998) and The Netherlands (Tuinstra et al., 1994) but lower in Canada (Craan and Haines, 1998). Much higher levels of DDT have been reported from regions with special pest problems. The sum of DDT compounds in breast milk was in India 6000 ng/g lipids (Jani et al., 1988), in Kwazulu 15 830 ng/g lipids (Bouwman et al., 1990) and in Zimbabwe 25 259 ng/g lipids (Chikuni et al., 1997). The levels of PCDDs and PCDFs are similar in Sweden, Norway, Finland, Estonia (Mussalo-Rauhamma and Lindstr om, 1995) and Lithuania (Becher et al., 1995). Much higher levels of TCDD (120 pg/g lipids) have been measured in breast milk from women living in agricultural regions of Kazakstan (Hooper et al., 1998). The Aral region is also highly contaminated with pesticides, indicating a pollution of great concern (Jensen et al., 1997). 4. Conclusions
Fig. 4. Concentrations an time related trends of PBDEs in human milk expressed as an exponential curve.
Fig. 5. Distribution of organohalogenated contaminants in human milk from 1972 to 1997.
The levels in milk re¯ect the mothersÕ exposure during their reached life time and the general pollution during that time. The decrease in the levels of pesticides and compounds originating from industrial usage con®rms the positive eects of restrictions and prohibitions applied to the usage of the compounds and other measures taken to minimize the pollution. However, the low rate of decrease in the levels of PCBs and dioxins indicate a prolonged exposure by these compounds that may be of concern also in coming decades. The current status, concerning the levels of organochlorine compounds in Swedish mothers and breast fed infants is much better than 20±30 years ago. An infantÕs exposure to the sum of organochlorine compounds in 1997 is estimated to 1/10 of that in 1972. At the same time the exposure to PBDEs has increased about 60 times. The exponential increase of PBDEs in breast milk is alarming and calls for measures to stop the exposure to PBDEs. Since also these
1122
K. Noren, D. Meironyte / Chemosphere 40 (2000) 1111±1123
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