Decreased sperm concentration, decreased total sperm count, decreased sperm vitality and decreased sperm motility result from contact with the common plastics chemical Bisphenol-A (BPA), according to a study appearing in the journal Fertility and Sterility. The new study adds to emerging human evidence questioning the safety of BPA, a chemical used in the production of the plastics and epoxy resins found in baby bottles, plastic containers, the linings of cans used for food and beverages, and in dental sealants.
The five-year research project involved more than 500 workers from factories in China and compared the workers who had high urine BPA levels with those with low urine BPA. Men with higher urine BPA levels had 2-4 times the risk of having poor semen quality, including low sperm concentration, low sperm vitality and motility.
This new study follows on from 2009 research that found that exposure to high levels of BPA in the workplace increases the risk of reduced sexual function in men.
"Compared with men without detectable urine BPA, those with detectable urine BPA had more than three times the risk of lowered sperm concentration and lower sperm vitality, more than four times the risk of a lower sperm count, and more than twice the risk of lower sperm motility," said the study's lead author, De-Kun Li, a reproductive epidemiologist at Kaiser Permanente's Division of Research in Oakland, California.
Li noted that urine BPA was not associated with semen volume or abnormal sperm morphology. "Similar dose-response associations were observed among participants with only environmental BPA exposure at levels comparable to men in the general United States population."
The study notes that despite a markedly reduced sample size in the group of men exposed only to low environmental BPA sources, the inverse correlation between increased urine BPA level and decreased sperm concentration and total sperm count remained statistically significant.
"The finding of the adverse BPA effect on semen quality illustrates two points: first, exposure to BPA now has been linked to changes in semen quality, an objective physiological measure. Second, this association shows BPA potential potency: it could lead to pathological changes of the male reproductive system in addition to the changes of sexual function," Li explained.
Worryingly, Li points out that semen quality and male sexual dysfunction could be more sensitive early indicators for adverse BPA effects than other disease endpoints that are more difficult to study, such as cancer or metabolic diseases.
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Source: Fertility and Sterility