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
1
2
3
4
5

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:

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 1. 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 5 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 1. 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 2. 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 2. 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. 1. 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. 2. 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;
1
Schecter et al. (1994); 2Paumgartten
et al. (2000); 3Schecter et al. (1990a);
4
Schecter et al. (1990b); 5Schuhmacher et al. (1999); 6Ministry of
Health Labor, and Welfare (1999);
7
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 5 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 1 to 4 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 2 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. 3. 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 3. 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 5 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 4. 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. 4. 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 4 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 4 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 4 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. 5. 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 1 to 4 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 do 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. 6. 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 Department, De La Salle University, Philippines.

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