When people ask whether modern synthetics are damaging their health and endangering future generations, Topic A is nearly always bisphenol A (BPA), a synthetic estrogen, an integral component of polycarbonate plastics and epoxy resins and one of the highest volume industrial chemicals in existence.

Now a ground-breaking study released in the journal of Human Reproduction offers what its authors call “the first evidence that exposure to BPA in the workplace could have an adverse effect on male sexual dysfunction.”

The scientific team, underwritten by Kaiser Permanente’s Division of Research in Oakland, CA., spent five years studying 634 Chinese factory workers whose bodies had been severely contaminated with BPA.

Animal studies link BPA to an extraordinary array of subtle but serious chronic health problems, including impairment of the ability to think and behave normally, reproductive and cardiovascular system damage, cancer, diabetes, asthma and obesity. Evidence of BPA’s impact on human health has been more elusive, which is why the Kaiser Permanente study is making headlines around the globe.

After a year of being bombarded with BPA, the Chinese workers reported disturbing sexual problems: four times as much erectile dysfunction and seven times as many ejaculation difficulties as a control group, the Kaiser team found.

Most people don’t experience BPA exposure nearly as intense as the factory workers. But nearly all Americans test positive for low-level BPA contamination, as evidenced by body burden testing by the U.S. Centers for Disease Control and Prevention, the Environmental Working Group and other academic and non-profit organizations.

As Kaiser research team leader De-Kun Li, MD, Ph.D., put it, the China workers study “raises the question: Is there a safe level for BPA exposure, and what is that level?”