男性體內塑化劑濃度過高 將降低伴侶懷孕勝算

Women whose male partners have high concentrations of three common forms of phthalates, chemicals found in hundreds of consumer products, take longer to become pregnant than women in couples in which the male does not have high concentrations of the chemicals, finds new research by scientists at the National Institutes of Health and other institutions.

The researchers assessed the concentrations of phthalates and bisphenol A (BPA) in couples trying to achieve pregnancy.

Pregnancy took the most time to achieve in couples in which the males had high concentrations of monomethyl phthalate, mono-butyl phthalate, and monobenzyl phthalate. Neither male nor female exposure to BPA was associated with pregnancy rates.

Phthalates, often called plasticizers, are a group of chemicals used to make plastics more flexible and harder to break. Some phthalates are used as solvents for other materials. They are used in hundreds of products, such as vinyl flooring, adhesives, detergents, lubricating oils, automotive plastics, wire coatings, plastic clothes, and personal care products, such as soaps, shampoos, hair sprays, and nail polishes.

Phthalates are used widely in polyvinyl chloride plastics, which are used to make products such as plastic packaging film and sheets, garden hoses, inflatable toys, blood-storage containers, medical tubing, and some children’s toys.

BPA is used to make some types of plastic containers, in the protective lining of food cans, and other products.

People are exposed to phthalates and BPA by eating and drinking foods that have been in contact with containers and by exposure to products containing the compounds, according to the U.S. Centers for Disease Control and Prevention.

The study authors measured urine concentrations of BPA and 14 phthalate compounds in couples trying to achieve pregnancy. The researchers enrolled 501 couples from Michigan and Texas from 2005 to 2009.

The researchers calculated the probability that a couple would achieve pregnancy by using a statistical measure called the fecundability odds ratio (FOR). The measure estimates couples’ probability of pregnancy each cycle, based on their urinary concentration of the compounds. A ratio less than one suggests a longer time to pregnancy, while a ratio greater than one suggests a shorter time to pregnancy.

BPA concentrations were not associated with a longer time to pregnancy However, male urinary concentrations of the three metabolites of phthalates were associated with approximately a 20 percent increase in the time it took for the couples to achieve pregnancy:

“The delays in pregnancy we saw were comparable to those seen for cigarette smoking or with obesity,” said the study’s first author, Germaine Buck Louis, PhD, director of the Division of Intramural Population Health Research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, or NICHD.

The American Chemistry Council maintains that phthalates are safe, saying, “Phthalates have been reviewed by numerous scientific panels and the conclusions have been essentially the same each time: that the phthalates used in commercial products do not pose a risk to human health at typical exposure levels.”