DSpace at VNU: Dioxins and related compounds in human breast milk collected around open dumping sites in Asian developing countries: Bovine milk as a potential source

Arch Environ Contam Toxicol 47, 414 – 426 (2004) DOI: 10.1007/s00244-004-3172-4 A R C H I V E S O F Environmental Contamination a n d Toxicology © 2004 Springer Science؉Business Media, Inc Dioxins and Related Compounds in Human Breast Milk Collected Around Open Dumping Sites in Asian Developing Countries: Bovine Milk as a Potential Source T Kunisue,1 M Watanabe,1 H Iwata,1 A Subramanian,1,2 I Monirith,1 T B Minh,1 R Baburajendran,2 T S Tana,3 P H Viet,4 M Prudente,5 S Tanabe1 Center for Marine Environmental Studies, Ehime University, Bunkyo-cho 2-5, Matuyama 790-8577, Japan Center of Advanced Study in Marine Biology, Annamalai University, Tamil Nadu, India Social and Culture Observation Unit, Cabinet of the Council of Minister, Kingdom of Cambodia Center for Environmental Technology and Sustainable Development, Hanoi National University, Hanoi, Vietnam Science Education Department, De La Salle University, Manila, Philippines Received: 11 August 2003 /Accepted: 14 March 2004 Abstract In this study, concentrations of dioxins and related compounds (DRCs)—such as polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls—were found in human breast milk from women living near dumping sites of municipal waste and reference sites in India, Cambodia, Vietnam, and the Philippines during 1999 to 2000 DRCs were detected in all human breast milk samples analyzed, demonstrating that residents in these Asian developing countries have been exposed to these contaminants In India, the concentrations of DRCs in human breast milk from women living near the investigated dumping site were notably higher than those from women living near reference sites and from women in other Asian developing countries Toxic equivalent quantity (TEQ) levels of DRCs were comparable with or higher than those reported in the general populations of developed countries since 1990 In contrast, levels of these contaminants in human breast milk in women from Cambodia and Vietnam were not significantly different between milk from women living near the dumping and reference sites These results indicate that significant pollution sources for DRCs are present in Indian dumping sites and that residents there have been exposed to relatively higher levels of these contaminants TEQ levels in human breast milk from the dumping site in India tended to decrease with an increase in the number of previous deliveries by mothers, whereas no significant relationship was observed in Cambodia, Vietnam, or the Philippines This suggests that mothers who have been exposed to relatively high levels of DRCs transfer greater amounts of these contaminants to the first infant than later ones through breast-feeding, which in turn implies that the first children of these mothers might be at higher risk from DRCs When the residue levels of DRCs in bovine milk collected from the Indian dumping site and reference sites were examined, TEQ levels in bovine milk from the dumping site were higher than those from reference sites This result sug- Correspondence to: S Tanabe; email: shinsuke@agr.ehime-u.ac.jp gests that bovine milk is a potential source of DRCs for residents living near the dumping site in India To our knowledge, this is the first comprehensive study on exposure to DRCs of residents living in proximity to open dumping sites of municipal waste in Asian developing countries Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are lipophilic-stable contaminants of great concern with respect to their toxic effects on humans and wildlife In developed countries, the residue levels of these contaminants in various environmental media and biota, including humans, have generally decreased in recent years (Alcock and Jones 1996; Bradley 2000; LaKind et al 2001; Nore´n and Meironyte´ 2000) because of highly efficient incinerators and strict regulations on production, use, and transportation of various chemicals In contrast, smaller numbers of studies have reported contamination status and temporal trends of these chemicals in developing countries, especially regarding human exposure, than developed countries (LaKind et al 2001) Asian developing countries—such as India, Cambodia, Vietnam, and the Philippines—located in the tropical region have large open dumping sites of municipal waste in the suburbs of major cities In these sites, varieties of municipal waste are dumped continuously and burned under low temperature by spontaneous combustion or intentional incineration It can be anticipated that dioxins and related compounds (DRCs) would be formed by such low-temperature combustion practices and that the surrounding environment may be polluted by these contaminants In addition, it can also be anticipated that PCBs would leach out from electric appliances dumped in these dumping sites We previously conducted a survey of DRCs in soils collected from these Asian developing countries and found that the residue levels of DRCs were higher in soils from the dumping sites than from the agricultural and urban soils collected far from these areas, indicating that the dumping sites Dioxins in Human Breast Milk are potential sources of DRCs (Minh et al 2003) From this we presumed that residents living near the dumping sites might be exposed to these contaminants because most of them obtain their livelihood by doing some dumpsite-dependent labor Especially, it is expected that in utero and lactational exposure to DRCs may adversely affect the brain development and immune systems of infants and children (Koopman-Esseboom et al 1994; Nagayama et al 1998a, b; Porterfield et al 1994; Weisglas-Kuperus et al 1995, 2000) To our knowledge, however, no study has reported on the exposure of residents living around the open dumping sites of municipal waste in Asian developing countries to these contaminants This study attempted to elucidate the contamination status of DRCs in human breast milk collected from the women living in proximity to dumping sites of municipal waste in India, Cambodia, Vietnam, and the Philippines and to assess the risk of exposure of infants to these contaminants We compared the present data with those from reference sites in the respective countries and also in the general populations of countries reported elsewhere so that we might understand the magnitude of contamination in human breast milk from the dumping sites In addition, we also examined the contamination of DRCs in bovine milk collected from cows around the dumping and reference sites in India, which was considered as one potential source of these chemicals to humans Materials and Methods Sample Collection Human breast milk samples (one sample from each mother) were collected from mothers living near open dumping sites of municipal waste in Perungudi, Chennai, India during August 2000 (n ϭ 11), in Meanchey, Phnom Penh, Cambodia during November 1999 and December 2000 (n ϭ 19), in Tay Mo, Hanoi, Vietnam during April 2000 (n ϭ 8), and in Payatas, Quezon, Philippines during February 2000 (n ϭ 9) The characteristics and the situations of the dumping sites in these countries have been reported previously (Minh et al 2003) Samples were also collected from mothers in Chennai (n ϭ 8), Phnom Penh (n ϭ 16), and Hanoi (n ϭ 10) on the same dates in locations at least 10 km away from the dumping sites (reference sites) We obtained informed consent from all the donors of milk samples, the details of whom are listed in Table All of these biological characteristics are not significantly different between the dumping and reference sites (p Ͼ 0.1) Bovine milk samples were collected from cows near dumping sites (cow n ϭ 2, buffalo n ϭ 3) and from cows near reference sites (cow n ϭ 3, buffalo n ϭ 2) in India All of the samples were collected in chemically cleaned containers and stored at Ϫ20°C until analysis Chemical Analysis During chemical analysis, extraction of human breast milk was conducted per the method reported by Hirai et al (2001) Cleanup and separation processes of human breast milk and chemical analyses of bovine milk were performed per the method recommended by the Ministry of Health, Labor, and Welfare of Japan with some modifications The following were spiked to 50 g human breast milk and bovine milk samples as internal standards: 13C12-labeled PCDD/DFs as well as non- and mono-ortho PCBs (2,3,7,8-TetraCDD/ 415 DF; 1,2,3,7,8-PentaCDD/DF; 1,2,3,6,7,8-HexaCDD/DF; 1,2,3,7,8,9HexaCDF; 1,2,3,4,6,7,8-HeptaCDD/DF; OctaCDD/DF; TetraCB77; TetraCB81; PentaCB118; PentaCB126; HexaCB156; HexaCB167; HexaCB169; and HeptaCB189) The human breast milk samples were added onto diatomaceous earth (Extrelut NT, Merck, Germany) packed in a glass column and extracted with diethyl ether The bovine milk samples were added into a glass separating funnel with saturated sodium oxalate solution ethanol, diethyl ether, and hexane and extracted twice Lipid in the extract was removed by gel permeation chromatography packed Bio-Bead S-X 3(Bio-Rad) Fifty percent dichloromethane in hexane was used as moving phase, and flow rate was set at ml/min First fraction containing lipid was discarded, and the next timed fraction containing DRCs was concentrated and passed through activated silica gel (Wako-Gel S-1; Wako Pure Chemical, Japan) packed in a glass column DRCs were eluted with hexane After concentration, the extract was spiked onto activated alumina (aluminium oxide 90 active basic, Merck) packed in a glass column The first fraction eluted with hexane contained most of the mono-ortho PCBs, and the second fraction eluted with 50% dichloromethane in hexane contained the remaining mono-ortho PCBs, the non-ortho PCBs, and the PCDD/DFs Then the second fraction was passed through activated carbon-dispersed silica gel (Kanto Chemical, Japan) packed in a glass column The first fraction was eluted with 25% dichloromethane in hexane to obtain the remaining mono-ortho PCBs and combined with the first fraction separated by alumina column Non-ortho PCBs and PCDD/DFs were eluted with toluene as the second fraction Both fractions were concentrated to near dryness, and 13C12-labeled PentaCB105, HexaCB157, and HeptaCB180 in decane were added to the combined first fraction; 13C12-labeled 1,2,3,4-TetraCDD and 1,2,3,7,8,9-HexaCDD in decane were added to the second fraction, all as injection spikes To determine lipid content in human breast and bovine milk, another 10-g sample was extracted, dried at 80°C, and weighed Identification and quantification were performed using a gas chromatograph (GC, Agilent 6890 series) with an autoinjection system and a bench-topped, double-focusing mass selective detector (MS, JEOL GC-Mate II) with a resolving power Ͼ3000 for mono-ortho PCBs and a high-resolution MS (JEOL JMS-700D) with a resolving power Ͼ10,000 for non-ortho PCBs and PCDD/DFs Both pieces of equipment were operated at an electron ionization energy of 38 – 40 eV, and the ion current was 600 ␮A DRCs were monitored by selective ion monitoring mode at the two most intensive ions of the molecular ion cluster among [M]ϩ, [M ϩ 2]ϩ, and [M ϩ 4]ϩ, except P5CDD, which was monitored at [M]ϩ and [M ϩ 2]ϩ All of the congeners were quantified using an isotope dilution method to the corresponding 13 C12-congeners when the isotope was within 15% of the theoretical ratio and the peak area was more than 10 times of noise Recoveries for the 13C12-labeled PCDD/DFs and coplanar PCBs were within 60% to 110% Toxic equivalent quantities (TEQs) were estimated based on human/mammal toxic equivalency factors (TEFs) proposed by the World Health Organization (WHO) (Van den Berg et al 1998) Statistical Analysis The Mann-Whitney U test was employed to detect the differences in concentrations of DRCs in human breast milk and characteristics of the mothers between the dumping and reference sites as well as the differences in concentrations affected by the number of deliveries per mother A p value Ͻ 0.05 was considered statistically significant These analyses were performed using StatView software (version 4.51.1; Abacus Concepts) 416 T Kunisue et al Table Details of the breast milk donors Mean (Range) India Characteristics Age (yr) Height (cm) Weight (kg) BMI (kg/m2) No previous deliveries Dumping Site (n ϭ 11) Cambodia Reference Site Dumping Site (n ϭ 8) (n ϭ 19) Vietnam Reference Site (n ϭ 16) Dumping Site (n ϭ 8) Philippines Reference Site (n ϭ 10) Dumping Site (n ϭ 9) 25.2 (20–34) 23.9 (19–29) 29.1 (19–46) 26.7 (18–38) 31.6 (22–42) 27.9 (22–34) 27.0 (17–44) Not measured Not measured 154.7 (144–165) 154.9 (145–160) 154.8 (145–162) 156.4 (150–160) 158.3 (152–165) Not measured Not measured 50.7 (39–68) 51.6 (41–60) 48.6 (45–60) 50.7 (40–60) 47.1 (35–68) Not calculated Not calculated 21.1 (17.5–27.2) 21.5 (17.9–26.7) 20.3 (16.4–22.9) 20.7 (16.6–25.0) 18.8 (15.1–27.4) 1.6 (1–3) 2.1 (1–3) 2.5 (1–6) 2.3 (1–4) 1.8 (1–4) 1.5 (1–3) 2.3 (1–6) BMI: Body mass index Results and Discussion Residue Levels in Human Breast Milk DRCs were detected in all of the samples of human breast milk analyzed in this study (Table 2), demonstrating that residents living near open dumping sites of municipal waste and reference sites in India, Cambodia, Vietnam, and the Philippines have been exposed to these contaminants The concentrations of PCDDs in human breast milk from dumping sites in different countries in decreasing order were as follows: India (mean [range] 290 [150 –780] pg/g lipid wt) Ͼ Philippines (190 [29 –730] pg/g lipid wt) Ͼ Cambodia (49 [14 –170] pg/g lipid wt) Ն Vietnam (32 [10 – 81] pg/g lipid wt) At the same time, the concentrations of PCDFs in decreasing order were as follows: India (50 [15–130] pg/g lipid wt) Ͼ Philippines (21 [5.9 – 44] pg/g lipid wt) Ն Vietnam (20 [7.3– 42] pg/g lipid wt) Ն Cambodia (15 [5.2–55] pg/g lipid wt) Furthermore, in India the concentrations of PCDD/DFs in human breast milk from the dumping site were higher than those from reference sites, whereas levels of these contaminants in human breast milk from Cambodia and Vietnam were not significantly different between the dumping and reference sites (Figure 1) These results indicate that significant pollution sources of PCDD/DFs are present in the dumping site in India and that the residents living near them have been exposed to relatively higher levels of these contaminants than residents in the other countries evaluated in this study The concentrations of non-ortho (mean [range] 260 [30 – 610] pg/g lipid wt) and mono-ortho PCBs (38,000 [2500 – 170,000] pg/g lipid wt) in human breast milk collected from mothers living near the dumping site in India were also higher than those of Vietnam women (non-ortho PCBs 62 [17–100] pg/g lipid wt, mono-ortho PCBs 24,000 [4200 – 46,000] pg/g lipid wt); Philippine women (non-ortho PCBs 76 [26 –160] pg/g lipid wt, mono-ortho PCBs, 8800 [1700 –28,000] pg/g lipid wt), and Cambodian women (non-ortho PCBs 51 [29 – 130] pg/g lipid wt; mono-ortho PCBs 8000 [820 –28,000] pg/g lipid wt) (Table 2) In addition, the levels of non- and especially mono-ortho PCBs in human breast milk from the dumping site of India were notably higher than those from reference sites (Figure 1) As in the case of PCDD/DFs described above, this fact indicates that pollution sources of non- and monoortho PCBs are also present in the dumping site and that residents living near there have been exposed to these contaminants It was previously reported that the concentrations of PCBs in various foods from urban and rural regions of India were relatively low (Kannan et al 1992b), which supports our finding In human breast milk from Vietnam, relatively high concentrations of mono-ortho PCBs were detected, but the levels were lower than those from the dumping site in India In a previous investigation of various foodstuffs from Vietnam, relatively high levels of PCBs were noted and the older transformers and capacitors imported from Russia and France were implicated as possible sources (Kannan et al 1992a) To understand the magnitude of contamination in human breast milk from dumping sites in India, Cambodia, Vietnam, and the Philippines, TEQ levels were compared with values for human breast milk from the general populations of other countries since 1990, which were selected from publications in which concentrations of all the isomers were reported (Figure 2) Because international TEFs were mainly used to calculate TEQs, the reported data were recalculated using WHO TEFs for comparison The levels of TEQs in human breast milk from India (38 pg TEQs/g lipid wt) were comparable with or higher than those from developed countries (Becher et al 1995; Dawailly et al 1992; Fuă rst et al 1994; Gonzalez et al 1996; Kiviranta et al 1999; Liem et al 1995; Ministry of Health, Labor, and Welfare 1999; Schecter et al 1990a; Schuhmacher et al 1999) and Russia (Schecter et al 1990b) This suggests that residents living near the dumping site in India have been exposed to comparable levels of DRCs as the general populations of developed countries In contrast, the levels of TEQs in human breast milk from Cambodia (9.2 pg TEQs/g lipid wt), the Philippines (12 pg TEQs/g lipid wt), and Vietnam (13 pg TEQs/g lipid wt) were lower than those from developed countries and comparable with those from other developing countries (Schecter et al 1990a, 1994; Paumgartten et al 2000) In this international comparison, however, there were some uncertainties such as age and parity of the mothers, sampling period, sample number, and accuracy of the analytical techniques involved In addition, very few data are available on non- and mono-ortho PCBs in the literature Because of such uncertainties, it was difficult to draw any firm conclusions using the information shown in Figure However, the observation that TEQs of DRCs in human breast milk from the dumping site of India were comparable with or higher than those from some developed countries, including Japan, is note- 970 (480–1500) 150 (75–350) 2900 (1300–5200) 67 (40–110) 1200 (360–4400) 310 (160–860) 390 (230–900) 120 (73–240) 160 (70–240) 18 (9.4–43) 180 (80–280) 6.3 (3.7–10) 2.0 (1.2–3.4) 8.3 (5.1–13) 91 (42–340) 6100 (2900–13,000) 2.2 (1.3–3.2) 1.2 (0.54–3.5) 12 (7.0–17) 1400 (130–4800) 210 (16–650) 4400 (440–16,000) 74 (9.8–230) 1300 (110–4300) 280 (21–830) 350 (41–1200) 77 (Ͻ2.1–250) 49 (14–170) 15 (5.2–55) 64 (21–180) 3.6 (0.87–6.8) 2.0 (0.79–4.6) 5.6 (1.9–12) 51 (29–130) 8000 (820–28,000) 2.1 (0.75–5.1) 1.5 (0.14–5.0) 9.2 (5.2–21) 810 (230–3000) 130 (Ͻ2.0–370) 2500 (670–7100) 46 (Ͻ2.0–130) 830 (230–2500) 260 (62–650) 240 (75–510) 70 (Ͻ2.2–200) 55 (20–150) 11 (4.4–24) 67 (28–180) 3.7 (0.07–8.3) 1.6 (0.67–3.2) 5.3 (0.93–11) 42 (19–79) 4900 (1300–12,000) 1.5 (0.70–2.5) 1.0 (0.26–2.2) 7.8 (1.9–15) 17 (8.0–45) 2.7 (1.0–4.3) 15 (9.5–24) 7.0 (2.1–17) 1.2 (Ͻ0.40–3.3) 1.5 (0.66–3.9) 2.0 (0.84–4.1) 1.8 (Ͻ0.60–5.3) 1.4 (Ͻ0.60–3.7) Ͻ0.60c Ͻ0.60c 1.8 (Ͻ0.60–7.8) Ͻ0.60c Ͻ1.1c 0.71 (Ͻ0.40–1.8) 2.3 (Ͻ0.40–5.0) 1.1 (Ͻ0.60–2.8) 3.1 (Ͻ0.60–5.7) 1.6 (Ͻ0.60–4.9) 7.7 (2.8–16) 39 (15–120) 2.2 (0.73–4.5) Reference Site (n ϭ 16) 4000 (750–8100) 590 (110–1200) 14000 (2500–27,000) 280 (40–1000) 3100 (500–6600) 600 (110–1200) 820 (130–1600) 120 (34–230) 32 (10–81) 20 (7.3–42) 51 (18–120) 2.7 (1.4–4.8) 3.3 (1.3–7.2) 6.0 (2.9–9.3) 62 (17–100) 24000 (4200–46,000) 3.5 (0.86–7.0) 4.0 (0.70–8.1) 13 (4.6–24) 15 (4.6–35) 5.0 (1.0–11) 34 (8.3–68) 8.0 (2.3–17) 1.5 (Ͻ0.40–3.6) 1.5 (0.54–2.4) 4.2 (1.2–8.6) 3.7 (1.2–12) 2.8 (1.5–4.6) Ͻ0.60c 2.2 (Ͻ0.60–7.7) 2.1 (0.78–3.0) Ͻ0.60c Ͻ1.1c 0.80 (0.48–1.2) 1.2 (0.71–3.0) 1.5 (Ͻ0.60–4.7) 3.1 (0.94–8.7) 1.7 (Ͻ0.60–5.8) 6.1 (2.0–17) 18 (5.3–45) 2.3 (0.78–5.3) Dumping Site (n ϭ 8) Vietnam 2400 (460–4500) 410 (61–1400) 8300 (1500–18,000) 130 (52–310) 2400 (420–9500) 490 (87–1800) 530 (100–1700) 97 (16–290) 27 (14–41) 20 (9.6–45) 47 (26–67) 2.9 (1.7–4.0) 3.4 (2.0–5.6) 6.3 (3.6–8.1) 56 (29–100) 15000 (2800–22,000) 2.5 (1.4–3.8) 2.8 (0.50–8.7) 12 (6.5–19) 19 (8.0–47) 3.8 (1.6–9.2) 24 (13–36) 9.6 (4.3–23) 1.0 (0.48–1.9) 1.3 (0.45–2.7) 4.5 (2.6–5.8) 4.5 (1.5–13) 3.6 (1.8–10) Ͻ0.60c 1.1 (Ͻ0.60–2.2) 2.8 (0.85–8.0) 0.70 (Ͻ0.60–2.6) Ͻ1.1c 1.0 (0.56–1.4) 1.5 (0.84–2.1) 0.84 (Ͻ0.60–1.4) 2.5 (Ͻ0.60–3.9) 1.1 (Ͻ0.60–2.0) 4.7 (1.6–7.2) 15 (7.1–25) 2.3 (0.68–4.3) Reference Site (n ϭ 10) 1400 (240–3800) 180 (26–490) 4600 (860–14,000) 100 (18–260) 1500 (230–6100) 340 (130–820) 510 (110–2000) 190 (64–550) 190 (29–730) 21 (5.9–44) 210 (35–770) 4.3 (0.21–14) 3.3 (0.83–9.3) 7.5 (1.0–23) 76 (26–160) 8800 (1700–28,000) 2.8 (0.76–8.2) 1.6 (0.31–5.6) 12 (5.0–37) 28 (16–99) 9.1 (Ͻ0.40–26) 27 (7.3–78) 12 (2.5–38) 2.4 (1.5–3.8) 1.4 (Ͻ0.40–2.8) 4.1 (Ͻ0.40–14) 3.6 (1.8–7.3) 2.7 (Ͻ0.60–6.8) 0.87 (Ͻ0.28–5.3) 1.7 (Ͻ0.60–4.4) 3.3 (1.5–7.8) Ͻ0.60c Ͻ1.1c 0.81 (Ͻ0.40–3.1) 2.0 (Ͻ0.40–7.9) 3.0 (Ͻ0.60–7.9) 5.2 (Ͻ0.60–12) 3.0 (0.66–6.4) 25 (4.3–55) 150 (23–650) 2.3 (0.27–3.6) Dumping Site (n ϭ 9) Philippines b The concentrations below detection limits were treated as zero for calculation of arithmetic mean and TEQ values T4: tetra, P5: penta, H6: hexa, H7: hepta, and O8: octa c All the samples were below detection limit DRCs: Dioxins and related compounds PCBs: Polychlorinated biphenyls PCDDs: Polychlorinated dibenzo-p-dioxins PCDFs: Polychlorinated dibenzofurans TEQ: Toxic equivalent quantity a 1.7 (0.53–4.9) 1.7 (Ͻ0.40–4.4) 2.2 (Ͻ0.40–5.8) 2.3 (0.48–8.8) 1.4 (Ͻ0.60–3.3) 0.88 (Ͻ0.60–8.5) 1.4 (Ͻ0.60–6.9) 1.9 (0.60–4.1) 0.71 (Ͻ0.60–5.4) 1.2 (Ͻ1.1–12) 1.9 (1.3–3.0) 2.0 (0.93–3.3) 2.1 (1.1–3.5) 3.4 (1.2–8.5) 1.7 (0.77–3.0) Ͻ0.60c 0.67 (Ͻ0.60–3.2) 3.9 (1.5–9.2) Ͻ0.60c 1.3 (Ͻ1.1–10) 18 (5.3–79) 5.4 (1.3–12) 21 (7.0–50) 6.5 (2.4–14) 1.2 (0.53–4.0) 1.6 (Ͻ0.40–3.9) 1.9 (Ͻ0.60–9.6) 3.3 (1.1–7.9) 1.8 (Ͻ0.60–7.0) 8.2 (1.8–28) 31 (7.4–130) 1.1 (0.58–2.1) 3.9 (2.4–6.9) 1.9 (Ͻ0.60–7.1) 5.8 (1.9–10) 2.0 (Ͻ0.60–7.3) 33 (11–74) 110 (53–160) 55 (18–260) 7.9 (2.3–37) 21 (13–31) 7.6 (3.4–12) 2.4 (0.58–4.7) 1.5 (1.1–2.1) Dumping Site (n ϭ 19) Reference Site (n ϭ 8) Dumping Site (n ϭ 11) Lipid (%) 2.3 (0.96–4.9) Dioxins 3.3 (Ͻ0.40–26) 2,3,7,8-T4CDD 1,2,3,7,8-P5CDD 7.3 (Ͻ0.40–31) 1,2,3,4,7,8-H6CDD 4.3 (1.5–12) 1,2,3,6,7,8-H6CDD 14 (2.9–45) 1,2,3,7,8,9-H6CDD 6.6 (Ͻ0.60–20) 1,2,3,4,6,7,8-H7CDD 55 (35–100) O8CDD 200 (110–670) Furans 2,3,7,8-T4CDF 4.7 (1.1–15) 1,2,3,7,8-P5CDF 4.1 (1.8–11) 2,3,4,7,8-P5CDF 11 (2.8–38) 1,2,3,4,7,8-H4CDF 6.4 (3.0–15) 1,2,3,6,7,8-H6CDF 5.9 (1.4–18) 1,2,3,7,8,9-H6CDF Ͻ0.60c 2,3,4,6,7,8-H6CDF 3.7 (Ͻ0.60–9.6) 1,2,3,4,6,7,8-H7CDF 12 (2.8–42) 1,2,3,4,7,8,9-H7CDF Ͻ0.60c O8CDF 1.8 (Ͻ1.1–14) Non-ortho PCBs 3,3Ј,4,4Ј-T4CB (77) 100 (11–270) 3,4,4Ј,5-T4CB (81) 36 (3.0–88) 3,3Ј,4,4Ј,5-P5CB (126) 100 (12–310) 3,3Ј,4,4Ј,5,5Ј-H6CB (169) 20 (3.3–88) Mono-ortho PCBs 2,3,3Ј,4,4Ј-P5CB (105) 7300 (400–29,000) 2,3,4,4Ј,5-P5CB (114) 860 (64–4800) 2,3Ј,4,4Ј,5-P5CB (118) 22000 (1200–92,000) 2Ј,3,4,4Ј,5-P5CB (123) 460 (19–1700) 2,3,3Ј,4,4Ј,5-H6CB (156) 4600 (280–26,000) 2,3,3Ј,4,4Ј,5Ј-H6CB (157) 1100 (95–5500) 2,3Ј,4,4Ј,5,5Ј-H6CB (167) 1900 (120–8200) 2,3,3Ј,4,4Ј,5,5Ј-H7CB (189) 310 (35–1400) Total PCDDs 290(150–780) Total PCDFs 50 (15–130) Total PCDD/PCDFs 340 (170–890) PCDDs-TEQsa 14 (1.1–56) PCDFs-TEQsa 7.7 (2.2–25) PCDD/PCDFs-TEQsa 21 (3.3–81) Total non-ortho PCBs 260 (30–610) Total mono-ortho PCBs 38,000 (2500–17,000) Non-ortho PCBs-TEQsa 10 (1.3–32) Mono-ortho PCBs-TEQsa 6.3 (0.45–31) a Total TEQs 38 (8.5–140) Compoundb Cambodia India Table Meana (range) concentrations (pg/g lipid wt) of DRCs in human breast milk from the dumping and reference sites in India, Cambodia, Vietnam, and the Philippines Dioxins in Human Breast Milk 417 418 T Kunisue et al Fig Comparison of the concentrations of DRCs in human breast milk from dumping (d) and reference (r) sites The circles and bars represent mean and range values, respectively ‫ء‬p Ͻ 0.05 ‫ءء‬p Ͻ 0.01 Fig Comparison of TEQ levels in human breast milk from dumping sites in Asian developing countries with those from other countries aPresent study, bPCDD/DFs only; Schecter et al (1994); 2Paumgartten et al (2000); 3Schecter et al (1990a); Schecter et al (1990b); 5Schuhmacher et al (1999); 6Ministry of Health Labor, and Welfare (1999); Gonzalez et al (1996); 8Dewailly et al (1992); 9Fuă rst et al (1994); 10 Becher et al (1995); 11Kiviranta et al (1999); 12Liem et al (1995) Reference data were recalculated by using WHO TEF (Van den Berg et al 1998) worthy In developed countries, it is claimed that the residue levels of DRCs in human breast milk decreased recently (La- Kind et al 2001) because of the installation of highly efficient incinerators and strict regulations on the production and usage Dioxins in Human Breast Milk of various chemicals In contrast, in Asian developing countries it can be anticipated that the pollution caused by DRCs may increase further, and hence residue levels in human breast milk may also increase in the future because the release of these contaminants are not at all controlled, even now Variation with Number of Deliveries and Risk Assessment for Infants It has been reported that concentrations of DRCs varied with factors such as number of deliveries by mothers and extent of breast-feeding (Beck et al 1994; Bates et al 1994; Hooper et al 1999; Iida et al 1999; LaKind et al 2001; Schecter et al 1998) In this study, we examined the relationship between number of deliveries by the mothers and TEQs in human breast milk from India, Cambodia, Vietnam, and the Philippines In India, data from the dumping site only were examined because significantly different levels of TEQs were observed between the dumping and reference sites (Figure 1) TEQ levels in human breast milk from the dumping site in India tended to decrease with an increase in the number of deliveries (Figure 3) In fact, one of the primipara donors had exceptionally high level of TEQs (140 pg/g lipid wt) In contrast, in Cambodia, Vietnam, and the Philippines no significant relationship was observed (Figure 3) These results suggested that the mothers who have been exposed to relatively high levels of DRCs, as in case of the mothers in developed countries, may transfer higher amounts of these contaminants to the first infant through breast-feeding than to infants born afterward fed in the same manner, hence the first-born children might be at higher risk from DRCs In previous investigations in developed countries (Beck et al 1994; Iida et al 1999), it was reported that concentrations of DRCs in human breast milk from primiparas were higher than those in multiparas Beck et al (1994) found that TEQ levels in German multiparas with three deliveries were 43% lower than those in primiparas To understand the magnitude of exposure to DRCs by infants, we estimated daily intake (DI) from the levels of TEQs in human breast milk observed in this study based on the assumption that an infant ingests 700 ml milk/d and that the weight of an infant is kg (Hooper et al 1997) As expected, the highest DI (500 pg TEQs/kg/d) was observed in the infants of mothers living near the dumping site in India, and DIs in all the cases exceeded to pg TEQs/kg/d, which is the tolerable daily intake (TDI) proposed by WHO (Van Leeuwen et al 2000) (Table 3) It has been reported that 1–3-month-old infants absorb Ͼ90% of 2,3,7,8-substituted PCDD/DF isomers (except hepta- and octa-CDD/Fs) contained in their mother’s milk (Dahl et al 1995; Korer et al 1993; McLachlan 1993; Pluim et al 1993), hence they may be exposed to relatively high levels of DRCs during this period If an infant’s consumption is to remain below the TDI, a decrease in human breast milk contamination must be sought In case of the subjects in this study, if the daily intake of TEQs should be Ͻ4 pg, an infant can ingest only 1% to 57% of the necessary amount of milk (700 ml/d) to stay below the TDI value Furthermore, in some Asian developing countries, water used for many formula milk preparations may contain various infectious organisms and environmental contaminants, which may adversely affect 419 infant health (Carpenter et al 2000) Considering all of the above, breast-feeding cannot be avoided for the infants in Asian developing countries and so finding ways to decrease levels of DRCs in human breast milk has become mandatory to save infants from possible toxic effects Because the majority of DRCs in human breast milk comes through mobilization from adipose tissue, and only a small amount (14%) comes from dietary sources (Koppe 1995), it is imperative that dioxin exposure should be decreased using urgent control and regulation of DRC pollution sources Residue Levels in Bovine Milk—A Potential Source Although residue levels of DRCs in soils collected from open dumping sites in Asian developing countries were apparently greater than those from the control sites (Minh et al 2003), the levels of DRCs in human breast milk from residents living near the dumping sites in Cambodia and Vietnam were not significantly higher than those from reference sites However, residue levels of these contaminants in Indian samples around the dumping site were notably higher (Table and Figure 1) This implies that residents living in proximity to the dumping sites in Cambodia and Vietnam have not been greatly exposed to DRCs originating from the dumping sites In the case of humans, it has been reported that the food chain, especially meat and dairy products, accounts for 98.8% of exposure to dioxins and that water, soil, and air are not major sources (Travis and Hattemer-Frey 1991) In addition, it has been suggested that residue levels and composition of DRCs in human tissues generally reflect those in ingested foods (Cole et al 1997; Domingo et al 1999; Fiedler et al 1997; Goldman et al 2000; Hooper et al 1999; Johansen et al 1996) In India, buffaloes reared near the waste-dumping site mainly feed on dumped leftovers, whereas cows reared near the dumping site feed mainly on pastures In addition, residents living near the dumping site constantly drink the milk collected from these bovines In contrast, in Cambodia, Vietnam, and the Philippines, livestock such as buffaloes and cows are not reared near dumping sites To elucidate whether bovine milk is a potential source of DRCs for residents in proximity to the dumping site in India, residue levels of these contaminants in buffalo milk and cow milk collected in and around the site were estimated In all of the bovine milk samples analyzed, DRCs were detected (Table 4), demonstrating that bovines in India have been exposed to these contaminants Concentrations of DRCs in buffalo milk collected near the dumping site (mean TEQs 16 pg/g lipid wt) were higher than those in cow milk collected near the dumping site (mean TEQs 7.3 pg/g lipid wt) and in bovine milk collected from reference sites (mean TEQs buffalo 2.1 pg/g lipid wt and cow 3.8 pg/g lipid wt) (Table 4) This indicates that buffaloes feeding at the dumping site in India consume greater amounts of DRCs through contaminated soils, waterweeds, and leftovers In addition, TEQ levels in cow milk collected near the dumping site were slightly higher than those from reference sites, implying that pastures near the dumping site are also contaminated by DRCs, probably formed in the dumping site and transferred via runoff or/and atmosphere to these pastures Compositions of PCDD/DFs in bovine milk showed differ- 420 T Kunisue et al Fig Relationship between concentrations of TEQs in human breast milk from Asian developing countries and number of previous deliveries (A) Indian dumping site, (B) Cambodian sites, (C) Vietnamese sites, (D) Philippines dumping sites ‫ء‬p Ͻ 0.05 Table Estimated daily intakes of TEQs from human breast milka Daily Intake (pg TEQs/kg/d) Country India Dumping site Reference site Cambodia Dumping site Reference site Vietnam Dumping site Reference site Philippines Dumping site Mean Range 120 28 28–500 18–35 31 24 7.6–67 2.4–55 42 39 14–55 10–60 39 1.9–130 a Estimated based on the assumption that an infant ingests 700 ml milk/d and that the weight of an infant is kg (Hooper et al 1997) ent patterns depending on the area of collection In bovine milk collected from the dumping site, some low chlorinated congeners—such as 2,3,7,8-T4CDD; 1,2,3,7,8-P5CDD; and 2,3,4,7,8-P5CDF—were predominant, whereas the residue levels of 1,2,3,4,6,7,8-H7CDD and O8CDD were relatively higher in those from reference sites (Figure 4) Furthermore, higher levels of T4, P5, and H6CDD/DFs were noted in bovine milk from the dumping site than that from reference sites (Figure 5) In particular, concentration ratios of these congeners of dioxins and furans observed in buffalo milk were higher than in cow milk, indicating that notable sources of T4, P5, and H6CDD/ DFs are present in the dumping site, and hence buffalos feeding there have been exposed to these contaminants Higher ratio of T4, P5, and H6CDD/DFs were observed in cow milk collected around the dumping site than those from reference sites, implying that pastures near the dumping site have been contaminated by these compounds In a previous study, we reported that concentrations of T4, P5, and H6CDD/DFs in soils from the Indian dumping site were higher than those from reference sites (Minh et al 2003) These results indicate that T4, P5, and H6CDD/DFs are formed in the dumping site in India, possibly by combustion of municipal wastes, and that buffaloes and cows feeding in and around these areas accumulate higher amounts of these compounds through contaminated soils, waterweeds, leftovers and pastures In soils collected in and around the Indian dumping site, however, 1,2,3,4,6,7,8-H7CDD and O8CDD were predominant among all the 2,3,7,8-substituted congeners (Minh et al 2003) In addition, Thomas et al (2002) reported that the estimated Dioxins in Human Breast Milk 421 Table Meana (range) concentrations (pg/g lipid wt) of DRCs in bovine milk from dumping and reference sites in India Dumping Site b Compound Lipid (%) Dioxins 2,3,7,8-T4CDD 1,2,3,7,8-P5CDD 1,2,3,4,7,8-H6CDD 1,2,3,6,7,8-H6CDD 1,2,3,7,8,9-H6CDD 1,2,3,4,6,7,8-H7CDD O8CDD Furans 2,3,7,8-T4CDF 1,2,3,7,8-P5CDF 2,3,4,7,8-P5CDF 1,2,3,4,7,8-H6CDF 1,2,3,6,7,8-H6CDF 1,2,3,7,8,9-H6CDF 2,3,4,6,7,8-H6CDF 1,2,3,4,6,7,8-H7CDF 1,2,3,4,7,8,9-H7CDF O8CDF Non-ortho PCBs 3,3Ј,4,4Ј-T4CB (77) 3,4,4Ј,5-T4CB (81) 3,3Ј,4,4Ј,5-P5CB (126) 3,3Ј,4,4Ј,5,5Ј-H6CB (169) Mono-ortho PCBs 2,3,3Ј,4,4Ј-P5CB (105) 2,3,4,4Ј,5-P5CB (114) 2,3Ј,4,4Ј,5-P5CB (118) 2Ј,3,4,4Ј,5-P5CB (123) 2,3,3Ј,4,4Ј,5-H6CB (156) 2,3,3Ј,4,4Ј,5Ј-H6CB (157) 2,3Ј,4,4Ј,5,5Ј-H6CB (167) 2,3,3Ј,4,4Ј,5,5Ј-H7CB (189) Total PCDDs Total PCDFs Total PCDD/Fs PCDDs-TEQsa PCDFs-TEQsa PCDD/Fs-TEQsa Total non-ortho PCBs Total mono-ortho PCBs Non-ortho PCBs-TEQsa Mono-ortho PCBs-TEQsa Total TEQsa Buffalo (n ϭ 3) Reference Site Cow (n ϭ 2) Buffalo (n ϭ 2) 8.7 (7.9–10) 5.5 (5.3–5.7) 7.8 (7.7–7.9) 2.4 (1.3–3.8) 3.7 (2.1–6.0) 0.78 (0.39–1.2) 3.3 (2.4–5.0) 0.87 (0.35–1.5) 2.6 (1.4–4.1) 1.3 (0.66–1.7) 0.69 (0.67–0.72) 1.9 (1.8–1.9) 0.38 (0.36–0.40) 1.7 (1.6–1.8) 0.52 (0.51–0.54) 1.3 (1.1–1.5) 0.85 (0.69–1.0) 0.20 (0.16–0.24) 0.49 (0.35–0.62) 0.31 (0.25–0.37) 1.2 (0.73–1.7) 0.23 (0.10–0.37) 1.5 (1.2–1.7) 0.81 (0.63–0.99) 0.42 (0.18–0.66) 0.35 (0.14–0.60) 4.0 (2.9–6.0) 1.6 (1.1–2.3) 1.5 (1.0–2.3) Ͻ0.050c 1.1 (0.84–1.6) 0.62 (0.34–0.96) Ͻ0.050c 0.19 (Ͻ0.10–0.38) 0.25 (0.22–0.29) 0.22 (0.21–0.22) 2.1 (2.0–2.2) 1.2 (1.2–1.3) 0.88 (0.85–0.91) Ͻ0.087c 0.69 (0.69–0.70) 0.29 (0.26–0.31) Ͻ0.087c Ͻ0.17c 9.0 (6.0–11) 9.7 (6.8–15) 60 (38–80) 9.7 (6.3–14) 2300 (1400–2900) 150 (100–180) 5300 (3300–6500) 110 (71–140) 670 (340–950) 190 (96–260) 240 (120–330) 33 (19–44) 15 (8.7–24) 9.8 (6.6–15) 25 (15–38) 6.6 (3.8–11) 2.5 (1.8–3.7) 9.1 (5.6–14) 87 (58–120) 8800 (5500–11,000) 6.1 (3.9–8.2) 1.3 (0.75–1.6) 16 (12–24) 7.7 (7.4–8.0) 6.9 (6.6–7.1) 27 (25–29) 4.7 (4.6–4.9) 550 (530–560) 51 (50–52) 1400 (1300–1400) 31 (30–32) 180 (170–180) 53 (51–55) 65 (62–68) 18 (16–19) 7.3 (7.0–7.7) 5.8 (5.7–5.8) 13 (13–13) 2.8 (2.8–2.9) 1.4 (1.3–1.4) 4.2 (4.1–4.3) 46 (44–49) 2300 (2200–2400) 2.7 (2.6–2.9) 0.33 (0.32–0.35) 7.3 (7.1–7.4) 0.10 (0.089–0.12) 0.065 (Ͻ0.052–0.091) 0.62 (0.59–0.65) 0.62 (0.62–0.62) 0.34 (0.20–0.48) Ͻ0.065c 0.24 (0.20–0.29) 0.32 (0.19–0.46) Ͻ0.065c Ͻ0.12c Cow (n ϭ 3) 3.5 (1.9–6.1) 0.21 (Ͻ0.065–0.48) 0.53 (0.19–0.82) Ͻ0.082c 2.1 (0.42–3.3) 0.28 (0.11–0.46) 2.5 (0.73–3.6) 2.5 (0.63–4.1) Ͻ0.065c 0.081 (Ͻ0.065–0.17) 0.90 (0.34–1.2) 0.73 (0.35–0.99) 0.40 (0.18–0.56) Ͻ0.082c 0.28 (0.10–0.43) 0.58 (0.18–0.91) Ͻ0.082c Ͻ0.16c 2.1 (1.9–2.3) 0.79 (0.60–0.98) 5.9 (5.6–6.2) 2.3 (1.8–2.8) 5.9 (2.4–10) 2.0 (0.86–2.7) 16 (5.3–24) 6.4 (1.2–11) 180 (120–240) 15 (9.1–21) 420 (270–560) 8.7 (5.3–12) 72 (44–100) 24 (15–32) 29 (20–37) 10 (7.6–13) 4.7 (3.8–4.7) 2.4 (2.0–2.8) 7.1 (5.8–8.5) 0.87 (0.63–1.1) 0.45 (0.44–0.46) 1.3 (1.1–1.6) 11 (9.9–12) 750 (500–1000) 0.61 (0.58–0.65) 0.12 (0.075–0.16) 2.1 (1.7–2.4) 480 (75–770) 93 (7.9–160) 2400 (230–3800) 34 (5.1–50) 330 (37–570) 110 (17–190) 140 (22–240) 25 (12–40) 8.2 (2.2–12) 3.0 (1.2–4.0) 11 (3.5–16) 1.0 (0.39–1.4) 0.60 (0.24–0.79) 1.6 (0.63–2.2) 30 (10–47) 3600 (410–5600) 1.7 (0.54–2.5) 0.56 (0.064–0.91) 3.8 (1.2–5.4) a The concentrations below detection limits were treated as zero for calculation of arithmetic mean and TEQ values T4: tetra, P5: penta, H6: hexa, H7: hepta, and O8: octa c All the samples were below detection limit DRCs: dioxins and related compounds, PCBs: polychlorinated biphenyls, PCDDs: polychlorinated dibenzo-p-dioxins, PCDFs: polychlorinated dibenzofurans, TEQ: toxic equivalent quantity b average percent contribution of high-chlorinated DD/DFs found in pastures affected through soil particle adhesion was greater than that of low-chlorinated DD/DFs and that during summer—the period of high atmospheric temperature— uptake of PCDD/DFs by pasture from vapor phase increased with increasing degree of chlorination (increasing KOA) Furthermore, Alcock et al (2002) showed that PCDD/DF pollution in cow milk reflected not only intake from pastures but also from ingestion of contaminated soils These facts show that intake of high-chlorinated DD/DFs—such as 1,2,3,4,6,7,8-H7CDD and O8CDD— by buffaloes and cows in and around the dumping site in India are greater than low-chlorinated DD/DFs However, in bovine milk from the dumping site, higher levels of low-chlorinated DD/DFs—such as T4, P5, and H6CDD/DFs— than high-chlorinated DD/DFs were observed This indicates that buffaloes and cows in and around the dumping site in India 422 T Kunisue et al Fig Compositions of PCDD/DFs in bovine milk collected from dumping and reference sites in India (A) Buffalo milk from the dumping site (B) Cow milk from the dumping site (C) Buffalo milk from reference sites (D) Cow milk from reference sites preferentially transfer greater amounts of low-chlorinated DD/ DFs to their milk Fries et al (1999, 2002) investigated the mass balance of PCDD/DFs in cows after administration of pentachlorophenol-treated wood and reported that transfer to milk and storage in body fat increased with decreasing degree of chlorination, whereas excretion in feces increased with increasing degree of chlorination These observations indicate notable pollution sources of low-chlorinated DD/DFs such as T4, P5, and H6CDD/DFs in and around the Indian dumping site Buffaloes and cows feeding there accumulate high amounts of these contaminants and transfer them to their milk, whereas in reference sites, comparatively low levels of pollution sources of T4, P5, and H6CDD/DFs were present Levels of non-ortho PCBs in bovine milk collected from the dumping site were also higher than those from reference sites, with the exception of H6CB 169 in cow milk (Table and Figure 4) This indicates that notable pollution sources of non-ortho PCBs are present at the dumping site in India and that buffaloes and cows obtain greater amounts of these contaminants via feeding, especially T4CB 81 and P5CB 126, and then transfer them to their milk In addition, levels of monoortho PCBs in buffalo milk collected from the dumping site were higher than those from reference sites (Table and Figure 4), whereas levels of mono-ortho PCBs in cow milk collected from the dumping site were comparable with or lower than those from reference sites (Table and Figure 4) Although a clear and plausible reason could not be assigned, it seems that some cows feeding near reference sites in India might have been exposed to levels of mono-ortho PCBs comparable with those near the dumping site Non-ortho PCBs are formed by combustion of municipal wastes (Sakai et al 2001), whereas they are poorly included in technical PCB mixtures (Schulz et al 1989; Takasuga et al 1995) In contrast, mono-ortho PCBs are abundant in technical PCB mixtures (Schulz et al 1989; Takasuga et al 1995) although less formed by combustion process (Sakai et al 2001) Further investigations regarding pollution and transfer of coplanar PCBs in bovine milk are needed Concentrations of all the DRCs in buffalo milk collected from the dumping site were higher than that collected from reference sites, indicating that daily intake of bovine milk by residents living near the dumping site in India is one of the possible reasons why TEQ levels in human breast milk collected from the dumping site were significantly higher than that collected from reference sites Furthermore, it was observed that not only buffaloes but cows near the dumping site also transfer higher amounts of low-chlorinated DD/DFs and nonortho PCBs to their milk than those near reference sites, implying that residents living near the dumping site in India are at greater health risk because of these highly toxic contami- Dioxins in Human Breast Milk 423 Fig Concentration ratios (dumping site to reference sites) of DRCs in bovine milk collected from dumping and reference sites in India DRC: Dioxins and related compounds NC: not calculated because values were below detection limits nants In India, consumption of dairy products is generally higher than in other countries, and average consumption of milk in India by one person per day increased from 135 g in 1980 to 176 g in 1990 (John et al 2001) The residents near the dumping site in India constantly drink the milk collected from buffaloes and cows reared near by Assuming that an adult weighing 60 kg drinks 176 g of the buffalo or cow milk investigated in this study/d, estimated daily intake of TEQs from bovine milk collected from the dumping site would range from to pg TEQs/kg/d—the TDI range proposed by WHO (Van Leeuwen et al 2000)—and only in one buffalo milk sample did the value exceed the TDI (Figure 6) Although the values are within the TDI, the residents living near the dumping site in India are exposed to considerably high levels of DRCs and hence may be at greater risk of exposure to these contaminants by way of bovine milk Conclusion To our knowledge, this is the first comprehensive study on exposure to DRCs in residents living near open dumping sites of municipal waste in India, Cambodia, Vietnam, and the Philippines In this study, we showed that residents living near dumping sites in these Asian developing countries have been exposed to DRCs In particular, our results suggest that residents near the dumping site in India have been exposed to relatively high levels of these contaminants, possibly through intake of bovine milk In addition, TEQ levels in human breast milk from residents living near the Indian dumping site tended to decrease with an increase in the number of previous deliveries by the mothers, suggesting that the primiparae living there transfer greater amounts of these contaminants to their infants through breast-feeding than multiparae This implies that first-born infants might be at higher risk from DRCs In open dumping sites of municipal waste in Asian developing countries, it is anticipated that pollution by DRCs may further increase and that residue levels in human breast milk may increase in the future because even now the sources of these contaminants are not regulated at all Control measures to regulate the pollution sources of DRCs in open dumping sites in Asian developing countries are urgently needed Further investigations on the effect of pollution and temporal trends on 424 T Kunisue et al Fig Estimated daily intake of TEQs by adults in bovine milk collected from dumping and reference sites in India Daily intake was estimated based on the assumption that an adult (60 kg) ingests 176 g of bovine milk/d (John et al 2001) DB: Buffalo milk from dumping site; DC: cow milk from dumping site; RB: buffalo milk from reference sites; RC: cow milk from reference sites wildlife and humans, especially infants, living near these sites would be indispensable Acknowledgments This study was supported by Grants-in-Aid for Scientific Research (A) (No 12308030) from Japan Society for the Promotion of Science and for Scientific Research on Priority Areas (A) (Grant No 13027101); the Research Revolution 2002 (RR 2002) Project for Sustainable Coexistence of Human, Nature and the Earth (FY 2002), and the 21st Century COE Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan Financial assistance was also provided by Formation and Behavior of Dioxins and their Related Persistent Organic Pollutants in Uncontrolled Combustion Processes from the Waste Management Research Grants of the Ministry of the Environment; the Core University Program between Japan Society for the Promotion of Science and National Center for Natural Science and Technology, Vietnam; and the Toyota Foundation The authors thank the following staff for help in sample collection: the Center of Advanced Study in Marine Biology, Annamalai University, India; the Department of Fisheries, Ministry of Agriculture, Forestry and Fisheries, Cambodia; the Center for Environmental Technology and Sustainable Development, Hanoi National University, Vietnam; and the Science Education 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DRCs In open dumping sites of municipal waste in Asian developing countries, it is anticipated that pollution by DRCs may further increase and that residue levels in human breast milk may increase... Matsueda T, Takenaka S, Nagayama J (1999) Polychlorinated dibenzo-p -dioxins and related compounds in breast milk of Japanese primiparas and multiparas Chemosphere 38:2461–2466 Johansen HR, Alexander... Nagayama J, Okamura K, Iida T, Hirakawa H, Matsueda T, Tsuji H, et al (199 8a) Postnatal exposure to chlorinated dioxins and related chemicals on thyroid hormone status in Japanese breast- fed infants