WASHINGTON – Exposure to high levels of a controversial chemical found in thousands of everyday plastic products appears to cause erectile dysfunction and other sexual problems in men, according to a new study published Wednesday.
The study, funded by the federal government and published in the journal Human Reproduction, is the first to examine the impact of bisphenol a, or BPA, on the reproductive systems of human males. Previous studies have involved mice or rats.
The research comes as government agencies debate the safety of BPA, a compound that is found in thousands of consumer products ranging from dental sealants to canned food linings and that is so ubiquitous, it has been detected in the urine of 93 percent of the U.S. population.
Researchers focused on 634 male workers at four factories in China who were exposed to elevated levels of BPA. They followed the men over five years and compared their sexual health with that of male workers in other Chinese factories where BPA was not present.
The men handling BPA were four times as likely to suffer from erectile dysfunction and seven times as likely to have difficulty with ejaculation, said De-Kun Li, a scientist at the Kaiser Foundation Research Institute, which conducted the study with funds from the National Institute for Occupational Safety and Health.
BPA, which was developed in the 1930s as a synthetic version of estrogen, appears to throw off the hormonal balance in the human body, Li said.
The workers studied did not have to spend years in the factory to develop problems – sexual dysfunction began in new workers after just months on the job, Li said.
The workers had levels of exposure to BPA that were 50 times what an average U.S. man faces. But the findings raise questions about whether exposure at lesser levels can affect sexual function, Li said. “This was a highly exposed group, and we see the effect,” he said. “Now, we have to worry about lower-level exposure.”
Li said the study is significant because chemical manufacturers and other defenders of BPA have long complained that research raising questions about its health effects was conducted on laboratory animals.
“Critics dismissed all the animal studies, saying, `Show us the human studies,’ ” Li said. “Now we have a human study, and this can’t just be dismissed.”
Since BPA is most readily absorbed through food and drink containers, health advocates have been particularly focused on how the Food and Drug Administration is regulating the chemical. The agency has maintained that BPA is safe. But a growing body of research over the past decade has linked BPA to a range of health effects in laboratory animals, including infertility, weight gain, behavioral changes, early onset puberty, cancer and diabetes.
Steven Hentges of the American Chemistry Council, which represents the chemical industry, said the new study has little meaning for consumers. “Although this study presents interesting information, it has little relevance to average consumers who are exposed to trace levels of BPA,” he said.
Still, concern about the chemical among consumers has created pressure in the marketplace. Manufacturers have pledged to take BPA out of baby bottles and water bottles. A handful of jurisdictions around the country have banned BPA from baby products, and similar measures are pending in state legislatures.
Last year, the FDA’s scientific advisory board criticized the agency for ignoring more than 100 academic and government studies that linked BPA with health effects. The Obama administration has pledged a “fresh look” at the issue, and the FDA is expected to complete that review by the end of this month.