Researchers at the University of Toronto in Canada say that they've found a link between prostate cancer in men and contraceptive use in women, but aren't sure what it means, says Freya Boardman-Pretty at New Scientist's Short Sharp Science blog. The team looked at levels of prostate cancer and contraceptive pill use in 88 countries and say there's a significant correlation between the two. But, says Boardman-Pretty, "exactly how female use of the pill causes prostate cancer in men is unclear."
"One hypothesis is that the level of pill use in a population gives an indication of the amount of sexual activity, which has previously been linked to prostate cancer," Boardman-Pretty says. But the Canadian researchers say it could also be that the estrogen-like chemicals that result in the urine of women taking the pill could be finding their way back into the water supply.