Forty years after the lesson taught by the notorious pesticide DDT, it might be hoped that fat-loving toxins would have been eliminated from human tissues. However, a US study has shown that levels of some flame retardants and organochlorine pesticides in breast milk are still high enough to warrant concern, despite many of them having been phased out of use.

Kurunthachalam Kannan and colleagues from the New York State Department of Health, US, took breast milk samples from 38 mothers in the state of Massachusetts, and analysed them for various flame retardants and organochlorine pesticides, such as DDT and lindane. They found that although levels varied widely between individuals, there was a clear correlation between amounts of different contaminants. This suggests a common source of exposure, which is likely to be household dust or food, says Kannan. 

The most prevalent contaminants in the samples studied, says Kannan, were polybrominated diphenyl ethers. These are flame retardants applied to household furnishings and electronic goods that are still widely used in many countries. The levels of these chemicals were between ten and 100 times higher than in Asian and European samples, which can be explained by the great market demand for them in the US, said Kannan. 

The scientists point out that despite the continued presence of these contaminants, breast milk is still the best food for babies. Gina Solomon, senior scientist at the Natural Resources Defense Council, a US-based non-governmental environmental and health advocacy organization based in New York, agreed. 'The benefits of breast milk still outweigh any harm from these contaminants, and we must control or eliminate the chemicals rather than stop mothers from breast-feeding,' said Solomon.

David Barden