To understand the degree of contamination by organochlorine compounds in human breast milk collected from Asian developing countries, concentrations of these contaminants observed in this study were compared with those reported from other countries in 1990s.

These two figures show international comparison of dioxins and PCBs concentrations in human breast milk.

Generally speaking, dioxin residue levels were apparently lower in developing countries than in developed nations.

However, dioxin levels in human breast milk from dumping site in India were higher than those in general public from other developing countries, and comparable to those from developed nations.

So far, it has been believed that the dioxin problem is a major issue in developed nations. No dioxin contamination and dioxin problems were known in developing countries other than some sporadic incidents such as herbicide agent orange in Vietnam and Yusho disease in Taiwan.

However, as I pointed out here, the dumping sites of municipal wastes can be a significant emission source of dioxins in some developing countries like India.

As seen in right figure, PCBs concentrations in human breast milk from Asian developing countries were lower than those from developed nations and former social countries.

As a whole picture, except for dumping site in India, contamination by dioxins and PCBs in human breast milk were higher in developed nations than in developing countries.

Global comparison of TEQs and PCBs concentrations in human breast milk

These two figures illustrates the comparison of DDTs and HCHs residue levels in developing and former social countries with those in developed nations.

As seen here, we can clearly say that contamination by organochlorine insecticides in human breast milk are much higher in developing and former social countries than in developed nations.

Global comparison of DDTs and HCHs concentrations in human breast milk

Earlier studies reported that concentrations of organochlorine compounds in human breast milk were affected by various factors, such as woman's age, number of children, lactational period, ect.

So, we attempted to examine the relationship between concentrations of organochlorine compounds detected at relatively high levels in this study and woman's age, and number of children.

The left two figures show the variation of dioxins and DDTs concentrations in human breast milk with woman's age.

As shown here, no significant correlation was observed with woman's age.

We considered that possible reason for it might be arisen from various number of children in lactating women.

Hence, the relationship between concentrations of these contaminants and number of children were examined and given in the two right figures.

As seen here, dioxins and DDTs concentrations in human breast milk tended to decrease with increase of number of children.

This means that organochlorines in mother's body are significantly excluded by the experience of nursing lactation and become less.

From this result, we can also guess that the first infants are exposed to higher levels of organochlorines from breast milk and might be at relatively higher risk of these contaminants.

This fact was found in developing countries, but it poses serious problems for humans in developed nations also. Namely, we can not ignore this fact, since this may be trouble of some concern.

Relationship between woman's age, number of children and concentrations of TEQs, DDTs in human breast milk

OK, back to the talk on the pollution in developing countries.

I would like to explain daily intakes of dioxins, HCHs, and DDTs from human breast milk by infants.

In this figure, the X-axis shows country, and the Y-axis indicates daily intake.

Daily intakes were calculated, based on the assumption that an infant ingests 700ml of milk per day and weight of an infant is 5kg.

The estimated daily intakes of dioxins by infants in all the four developing countries exceeded TDI proposed by WHO in 1998.

Furthermore, in Indian infants, the daily intake of HCHs also exceeded TDI proposed by health Canada in 1996.

Estimated daily intakes for infants based on TEQs, HCHs, and DDTs concentrations in human breast milk

In order to assess the toxic effects of POPs, we compared the levels of thyroid hormone and Vitamin A in serum of blood with dioxin concentrations in breast milk from lactating woman.

By the result shown in this slide, no significant correlation could be found for all the thyroid hormones, indicating less effect of dioxins on thyroid hormones.

Relationship between TEQs concentrations in human breast milk and thyroid hormone levels in serum

However, as seen here, significant negative correlation was observed between TEQ concentrations of dioxins in human breast milk and Vitamin A levels in serum in the blood from India and Cambodia.

This may suggest an acceleration of vitamin A metabolism or the inhibition of vitamin A formation by dioxins in human body.

Relationship between TEQs of dioxins and related compounds in human breast milk and vitamin A levels in serum

The accelerated metabolism of vitamin A by dioxins forms active metabolites such as retinoic acid, and it leads to an imbalance of metabolic contents.

It is well known in the experimental animals that the imbalance of retinoic acid cause growth retardation, skin disease and malformation.

Proposed Mechanism of Plasma Vitamin A Depletion by Exposure to Dioxins

In slum near to dumping site, we found some deformities and diseases, in the people living there.   This is a case of malformation in fingers.

This is a case of malformation in legs.

We also noticed Intellectual impediment in some individuals, as in the case of the small boy you see here.

This is a case of deficience in leg and arm. Of course, we have no clear evidence yet to specify the cause of these abnormalities, but we should consider toxic contaminants originating from dumping sites as one of the possible cause. The additional epidemiological studies and POPs monitoring are required in dumping site populations in developing countries.

The first, second and third conclusions indicate the widely contamination by POPs in human breast milk of residents in Asian developing countries. Particularly, Indian residents around dumping site were found to highly expose to dioxin related compounds as well as organochlorine insecticides.

Forth conclusion is that,
The first infant is exposed to higher levels of POPs from human bresat milk and might be at relatively higher risk by these contaminants.

Fifth conclusion is that,
The estimated Daily intakes of some POPs by infants in some developing countries exceeded TDI.

Final conclusion is that,
Significant negative correlation was observed between TEQs of dioxins in human breast milk and Vitamin A in serum. It may suggest a part of dioxin effect on the human health in dumping site.

As I presented on yesterday, very high levels of dioxin and its related compounds have been found in Malaysian dumping sites. This result indicates that similar satiation might be expected in other countries. Thus, further studies are needed in dumping sites in Asian developing regions, and emission control for dioxins and PCBs is requested.
 
Thank you for your attention.