Atrazine’s hormone disrupting powers unravelled

Scientists in Japan have unpicked the cellular processes causing the pesticide atrazine to have a feminising effect (ENDS Report 336, pp 20-23 ).1 Their findings explain why the effect is only seen in some cells.

Atrazine’s ability to increase concentrations of the enzyme aromatase, which turns testosterone into oestrogen, has been known for some time but the chemical pathway had not been fully described.

It now appears the process only takes place in tissues or cells where the production of aromatase is regulated by a region of DNA called aromatase promoter II - one of six possible aromatase promoters in humans.

The study was carried out on human cell lines. Similar tools are not available for most animal species but the results are likely to be significant for wildlife as aromatase promoter II plays a role in the sexual development of all vertebrates.

The study also has implications for human cancers as oestrogen boosts the growth of breast and prostate cancer cells, both of which use aromatase promoter II.

Researchers in the US have blamed high surface water concentrations of atrazine for declining frog and toad populations.

Its use has been restricted in the UK since 1993 and it will be banned completely from the end of 2007. A 2004 survey found it in about a third of groundwater samples (ENDS Report 382, p 19 ).