Declines seen in levels of persistent organic pollutants in mothers' milk.

Lignell S, M Aune, PO Darnerud, S Cnattingius and A Glynn. Persistent organochlorine and organobromine compounds in mother's milk from Sweden 1996–2006: Compound-specific temporal trends. Environmental Research doi:10.1016/j.envres.2009.04.011.

Levels of some chemicals banned decades ago are following a similar downward trend in people as they are in the environment.

A new study of Swedish women confirms that PCBs – a chemical used in electronics and transformers until the 1970s – and dioxins and furans – byproducts of industrial processes – are less prevalent in breast milk now than in the mid 1990s.

This is consistent with reports that levels of these chemicals have decreased in wildlife and food during the same time period.

However, the study provides surprising new news about PBDEs – a class of brominated flame retardant chemicals whose use increased worldwide during the 1990s. Although earlier studies showed that PBDE levels in mothers’ milk increased between 1970 and 1998, this study is the first to show that levels of some PBDEs seem to have tapered off and even decreased since 1995.

Levels of two common PBDE compounds, known as BDE-47 and BDE-99, decreased by 4 percent and 8 percent per year, respectively. Levels of BDE-100 appeared to remain constant and levels of a fourth type, BDE-153, increased by 5 percent per year.

PBDEs have been associated with disruptions in sex hormone and thyroid hormone balance and alterations in brain function and behavior in laboratory animals. Few studies have examined their health impacts on humans.

PBDE compounds have been banned in Europe and several US states. Legislation to further limit use in pending in many regions.