Despite being banned almost 30 years ago, the pesticide DDT is still being widely found in human bodies, a leading health researcher says.

In a study of 146 human milk samples, most of the Persistent Organic Pollutants (POPs) found belonged to the DDT group, Professor Tze Wai Wong of The Chinese University of Hong Kong will tell the CleanUp 2011 Conference in Adelaide today.

“DDT was only one type of contaminant we found,” Prof Wong said.

“There were also dioxins, other organochlorines and banned pesticides that were once widely used in agriculture.

“Finding them in human milk indicates that these pollutants are still present in food chain, which means that they’re highly persistent and have a slow decline rate, or, worse still, are still being used in some countries in food production– neither of which is good news for consumers.”

Prof Wong explained that human uptake of dioxins and other POPs is mostly from contaminated food products that originate from places with heavily-polluted soil and water. Dioxins can also enter the body through contaminated air.

The problem was not confined to the Asia-Pacific, but could be found across the world. Apart from previous use of toxic pesticides, the community’s diet, its methods of waste disposal and its level of industrialisation could also contribute to the uptake of POPs.

“We suspect that high concentrations of DDT will be found in communities which consume large amounts of seafood, dairy products, cattle and poultry, as animals tend to bioconcentrate these toxins,” Prof Wong said.

“In this case, Western Europe, Scandinavia and Japan are particularly at risk. People in China and Japan may also have high concentrations of dioxin in their bodies, as waste is often incinerated which release this compound into the environment.”

Research tended to show-up pollutants which were present in the human environment decades ago, and are still around, rather than more recent contaminants.

“We’re measuring what was prevalent in the past. Its persistence shows that we need to be cautious about what we are doing now, because the effects of today’s pollutants on health are not likely to be felt until some decades later,” Prof Wong said.

He recommended increased vigilance in food production, and especially over attempts to introduce new chemical compounds into the food chain.

“We have always been quick to come up with alternative chemicals to replace old or banned ones. This is often done without asking health researchers to examine their effects on the human body. Industry and scientists need to start working together better.”

“We also need to choose our food more wisely and rethink our dietary choices. Nutrition and flavour shouldn’t be our only considerations when planning meals. We also need to think about which foods may also contain high levels of contaminants.”

The Adelaide conference is being hosted by the CRC for Contamination Assessment and Remediation of the Environment (CRC CARE).