It’s been linked to breast cancer in women and brain damage in children, and a new study suggests that the chemical bisphenol-A, or BPA, may cause sexual dysfunction in men as well.

A five-year study that followed 634 factory workers in China found that those working in BPA manufacturing facilities had four times the risk of erectile dysfunction and seven times the risk of ejaculation difficulty as those in a control group where no BPA was present.

BPA is an endocrine disrupter that can mimic human hormones. It’s found in a variety of plastic products including baby bottles, plastic containers, dental sealants and the lining of cans used for food and beverages.

Previous studies have found that BPA interferes with male sexual function in mice and rats, but this was the first study to look specifically at the effect on humans.

The study, done by Kaiser Permanente and funded by the U.S. National Institute of Occupational Safety and Health, adds to a chorus of concerns about the safety of the chemical.

Dr. De-Kun Li, a reproductive and perinatal epidemiologist at Kaiser Permanente's Division of Research, stresses that the factory workers are exposed to 50 times more BPA than the average American male is likely to face.

"Because the BPA levels in this study were very high, more research needs to be done to see how low a level of BPA exposure may have effects on our reproductive system."

Sexual dysfunction may just be the tip of the iceberg in terms of long-term health effects of BPA exposure, says Dr. Li. Other disease endpoints like cancer or metabolic diseases are more difficult to study.

"This study raises the question: Is there a safe level for BPA exposure, and what is that level? More studies like this, which examine the effect of BPA on humans, are critically needed to help establish prevention strategies and regulatory policies."