MONDAY, Oct. 14, 2013 (HealthDay News) -- Two plastics chemicals -- bisphenol A (BPA) and phthalates -- may reduce the reproductive ability of both men and women, according to a new pair of small, early studies.
Women with high levels of BPA in their blood have an 80 percent increased risk of miscarriage when compared to women with little or no BPA, reported study co-author Dr. Ruth Lathi.
"BPA at time of conception was significantly higher in those who miscarried compared to those who had a live birth," said Lathi, an assistant professor of obstetrics and gynecology at the Stanford University Medical Center, in Palo Alto, Calif.
Meanwhile, couples can experience a 20 percent reduction in their reproductive capability if the male partner has high phthalate concentrations, according to a study funded by the U.S. National Institute of Child Health and Human Development.
Both studies were scheduled for presentation this week at the joint meeting of the International Federation of Fertility Societies and the American Society for Reproductive Medicine, held in Boston.
The pair of studies should add to growing concerns over the effect of environmental chemicals on reproduction, birth outcomes and early childhood development, said Dr. Linda Giudice, president of the American Society for Reproductive Medicine.
"It's important we don't scare people," Giudice said. "The aim is to inform people to minimize risk and maximize health."
However, a representative from the trade group American Chemistry Council (ACC) disputed the associations claimed by the researchers.
"These studies both appear to be small-scale studies that cannot establish any cause-and-effect relationship," said ACC spokeswoman Kathryn Murray St. John. "They are based on single samples to monitor exposure and so it is difficult to draw any meaningful conclusions."
BPA and phthalates are chemicals used in the production of plastics. Phthalates are no longer used to make baby products such as teething rings and pacifiers, and BPA has been banned for use in sippy cups, baby bottles and infant formula packaging.
Some doctors are concerned that the chemicals disrupt the function of hormones in the human body and could have harmful effects on unborn children.
The widespread exposure to these chemicals has further increased concern. For example, nearly all Americans have detectible levels of BPA in their urine, according to the U.S. Centers for Disease Control and Prevention.
The first study involved 114 women recruited during early pregnancy testing. Researchers took blood samples, then compared BPA levels in their blood to the outcome of their pregnancies.
BPA levels were higher among women who miscarried, Lathi said. Researchers could not say exactly why, however.
"Until further studies are performed, women with unexplained miscarriages may avoid BPA to reduce one potential risk factor," she said.
In the second study, doctors took urine samples from 501 couples who decided to attempt pregnancy between 2005 and 2009.
Researchers tested the urine for BPA and phthalates. Couples kept daily journals on their intercourse, lifestyle, menstruation and pregnancy test results. They were monitored until they either conceived or a year passed without conception.
Statistical analysis revealed that male -- but not female -- phthalate concentrations are associated with a roughly 20 percent reduction in reproductive success. It took longer for couples to conceive, if they conceived at all, when men carried high levels of phthalates.
Couples who are pregnant or attempting to become pregnant should avoid contact with potential sources of phthalates or BPA, Lathi and Giudice said.
That may be harder than it sounds. For example, BPA and phthalates can spread by touch as well as by ingestion, and cash register receipts and canned food linings often contain BPA resins, Lathi said.
People should avoid using plastic containers to microwave foods, as the chemicals from the plastic can leach into the edibles. "Don't leave your plastic water bottle in your car in the sun and have it heat up a lot," Giudice added. "The levels of BPA increase about a thousand-fold in a bottle that's been sitting in the sun."
Industry spokeswoman St. John said the studies should not cause any alarm.
"It is important to note that both of the studies rely on analysis of single-spot samples of blood or urine to measure BPA exposure," she said. "Studies of this type have essentially no capability to establish a cause-effect relationship since BPA has only a very short half-life in the body and, as a result, levels in blood or urine will have very high variability even within a day."
She added that public health officials continue to take a long, hard look at the safety of these chemicals and so far have not sounded any warning bells.
"The weight of scientific evidence on BPA has been extensively evaluated by government and scientific bodies around the world, which have declared the chemical safe as used in food contact," St. John said. "As recently as June of 2013, [the U.S. Food and Drug Administration] updated its perspective on BPA, stating that BPA is safe at the very low levels that occur in some foods and the use of BPA in food packaging and containers is safe."
Because they were presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
For more about bisphenol A, visit the U.S. Centers for Disease Control and Prevention.