Selasa, 12 Jun 2012
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High BPA levels linked to male sexual problems Study in
is likely to bring further scrutiny of the common chemical : China
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
population. Researchers focused on 634 male workers at four factories in U.S. 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. China
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. 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
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." U.S.
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 G. 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. Meanwhile, the federal government announced last month that it is giving $30 million to researchers across the country over the next two years in an aggressive push to advance knowledge about BPA and end the debate about its safety.
NEW YORK _ Male factory workers in
who got very high doses of a chemical that's been widely used in hard plastic bottles had high rates of sexual problems, researchers reported Wednesday. China
Heavy exposure to BPA, or bisphenol A, on the job was linked to impotence and lower sexual desire and satisfaction, according to the study, which adds to concerns about BPA's effects on most consumers.
The men in the study experienced BPA levels about 50 times higher than those faced by typical American men, said researcher Dr. De-Kun Li. "We don't know" whether more typical doses have similar effects, he said. People shouldn't be alarmed by the finding, said Li, a reproductive and perinatal epidemiologist at Kaiser Permanente's research division in
. But he said it would be prudent to limit exposure to BPA while scientists look for any effects from lower doses. The Oakland, California government recently announced new funding for research into BPA's effects. U.S.
Li is lead author of the latest study, published online Wednesday by the journal Human Reproduction. The work was financed by the National Institute of Occupational Safety and Health.
BPA is used in a wide variety of consumer products, including some hard plastic bottles and metal food or beverage cans. Several makers of baby bottles recently said they had stopped using the chemical. Some 90 per cent of the
population carries detectable levels in the urine. U.S.
Scientists are concerned that BPA exposure might harm the reproductive and nervous systems, and possibly promote prostate and breast cancers. Last year, a preliminary study linked BPA to possible risks for heart disease and diabetes.
The Food and Drug Administration concluded last year that trace amounts of BPA that leach out of bottles and food containers are not dangerous. But the FDA is now reviewing that stance after criticism from its scientific advisers. For the new research, Li and colleagues studied 164 factory workers in
who were exposed to high levels of BPA on the job. They were compared to 386 other men in the same town who either worked at other factories or were married to factory workers. The scientists measured BPA exposure through air sampling, and interviewed the workers about their sexual functioning. China
Compared to the other workers, men with high BPA exposure were about four times as likely to report trouble achieving erections, about seven times as likely to say they had difficulty ejaculating, and about four times as likely to report low sex drive or low satisfaction with their sex lives.
The effects are dramatic and "pretty clearly related to the exposure," said Linda Birnbaum, director of the National Institute of Environmental Health Sciences, who was not involved in the research.
The finding fits in with animal studies and should be followed up by research in the general population, she said. Her institute said last month it will spend more money on BPA-related research, bringing the total to US$30 million over two years.
Steven Hentges, a BPA expert and official with the American Chemistry Council, an industry group, said the work is "probably not very relevant for consumers."
For one thing, the reported 50-fold difference in exposure seems to be an underestimate because of how it was calculated, he said. In addition, he said, the workers inhaled BPA or got it on their skin. Consumers get it through diet instead, which lets the body detoxify it, Hentges said.
Li said the workers probably were exposed not only through inhalation and skin contamination but also by swallowing BPA powder that contaminated their food. He said he didn't know which route was most prominent in the Chinese factories.
Human Reproduction: http://humrep.oxfordjournals.org/
FDA statement on BPA: http://www.fda.gov/NewsEvents/PublicHealthFocus/ucm064437.htm 16:31ET 11-11-09
2009, The Canadian Press.