WASHINGTON - Exposure to high levels of a chemical found in thousands of everyday plastic products appears to cause erectile dysfunction and other sexual problems in men, according to a study published yesterday.
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 found in thousands of consumer products ranging from dental sealants to canned-food linings. It is so ubiquitous that 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 body's hormonal balance, 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 lower exposure can affect sexual function, Li said.
Li said the study was significant because chemical manufacturers and other defenders of BPA had long complained that research questioning its health effects was done 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 said BPA is safe but is conducting a review due this month. A growing body of research over the last decade has linked BPA to a range of health effects in lab animals, such as infertility, weight gain, behavioral changes, early-onset puberty, and cancer.
Steven Hentges of the American Chemistry Council, which represents the chemical industry, said the new study had little meaning for consumers because "they are exposed to trace levels of BPA." Still, manufacturers have pledged to take BPA out of baby bottles and water bottles.