High levels of DDT were found in the breastmilk of new mothers in Hong Kong even though the pesticide has long been banned in many places, including Hong Kong and China, a scientist said on Friday.
The findings by researchers from Hong Kong’s Baptist University suggest that DDT is still being illegally used in mainland China, on which Hong Kong depends for most of its food supplies, he said.
The study of a group of 37 Hong Kong mothers was carried out between 1999 and 2000, but the researchers who published the study this month said the results still held good.
“When you compare it with similar studies in other countries, Hong Kong’s DDT problem is serious,” Chris Wong Kong-chu, a biology associate professor at the Baptist University told Reuters in an interview.
DDT fully absorbed by infants
If found in human breastmilk, persistent organic pollutants such as DDT can be fully absorbed by infants.
DDT was banned in 1972 in the United States after it caused reproductive damage to birds such as the brown pelican and bald eagle, but it can remain in the environment for a long time. It also has been shown to increase the growth of breast cancer cells.
“Even though the samples were taken in 1999 and 2000, the results definitely still apply and are representative,” said Chris Wong.
“These pollutant accumulations take place over a very long period of time and even if we collect the samples again from the same subjects, they will show the same level of DDT concentrations,” he said.
The team led by biology professor Wong Ming Hung collected breastmilk and fatty tissue from the abdomens of the new mothers.
They found an average of 2.79 micrograms of DDT per gram of fat in Hong Kong mothers who were tested, far exceeding levels found in countries such as Japan (0.78), Italy (1.98) and the United States (2.52). The situation was only worse in China (7.6) and Mexico (5.66).
The report said the high level of DDT in Mexico was understandable because DDT had been widely used for malaria control before it was banned recently.
Pesticide banned in China in 1983
But for DDT to turn up in China and Hong Kong was surprising because the pesticide has been banned in the region since 1983.
“This is possibly due to the fact that there may be some illegal use of DDT in China...” the scientists said in the paper, published this month in the Archives of Environmental Contamination and Toxicology.
Chris Wong said DDT probably found its way into the Hong Kong women through the fish they consumed. Most of the fish sold in Hong Kong are caught in Chinese waters.
“The sea is a huge dumping site and pollutants get into the fish. We asked our subjects how much fish they consume, and we found a correlation. The higher the seafood consumption, the higher the DDT content,” he said.
Scientists say it has not been conclusively established what damage DDT does to infants. But a recent U.S. study found that a group of mothers with elevated levels of DDT suffered premature deliveries and had babies who were underweight.
“What we need is closer monitoring of this pollutant in the environment, in food and in people in this area and we have to see if this problem will get worse,” he said.