Researchers at Texas Tech University who looked at exposures to low levels of both arsenic and oestrogen found that low doses of both chemicals together – even at levels low enough to be considered “safe” for humans if they were on their own – can cause cancer in prostate cells.

J Treas and others. Chronic exposure to arsenic, estrogen, and their combination causes increased growth and transformation in human prostate epithelial cells potentially by hypermethylation-mediated silencing of MLH1, The Prostate, published online ahead of print, 26 June 2013. Texas Tech University news release. Risks 614.