Increased use of  birth control pills by women may be linked to the rising prostate cancer in men, according to a study published today in the British Medical Journal Open.

The study found that countries with the highest number of women on the pill were more likely to have a higher number of men who are diagnosed with prostate cancer. The finding suggests for the first time a potential link between the pill and prostate cancer, the researchers said.  

It’s unclear what exactly could tie the pill to prostate cancer, but researcher said estrogen hormones released in urine that recycle through the water supply could account for one possible explanation.

“There’s reason to suggest there’s an environmental component [to prostate cancer] and not solely genetic,” said Dr. Neil Fleshner, head of urology at the University Health Network in Ontario and co-author of the study.

Previous studies suggest that certain chemicals like pesticides and medication contaminated water are to blame for a rise in endocrine related diseases including certain types of cancer and early onset of puberty.  

Fleshner agreed their findings produce more questions instead of answers, and their hypothesis is based on speculation.

Men living in continents like North America and Europe are at higher risk for prostate cancer, and countries within those nations also have a higher use of oral contraceptives, they found.  

Fleshner and his colleague looked at the use of other types of birth control such as intrauterine device, condoms, and vaginal barriers, but found no association to prostate cancer compared to areas where use of the pill was prevalent.

“This is just a hypothesis generating idea,” said Fleshner. “Women should not be throwing away the pill because of this.”