A study released today claims pregnant women exposed to higher levels of two types of phthalates had sons with "less masculine" play behaviors.
Phthalates are colorless chemicals primarily used in many consumer products. Research evidence has indicated the chemicals may lower testosterone levels in humans and animals.
The study, published in the International Journal of Andrology, examined what researchers called the "two phthalates of most concern" -- diethylhexyl phthalate (DEHP) and dibutyl phthalate (DBP) -- that are used in food processing, soaps, cosmetics, air fresheners, and medical tubing.
Researchers found women exposed to higher levels of DEHP and DBP during their pregnancies had preschool aged sons who were less likely to play with "male typical" toys and games. Those "male typical" toys and games include trucks and play fighting.
The study's lead researcher, Dr. Shanna Swan, professor in Obstetrics and Gynecology at the University of Rochester School of Medicine and Dentistry, and director of the university's Center for Reproductive Epidemiology, said the findings are important for two reasons:
• They suggest that early exposure to phthalates can influence brain development.
• They are consistent with previous studies that have found DEHP and DBP can lower testosterone in humans, and are associated with genital changes in boys, including smaller genitals and incomplete descent of the testicles.
"There are definitely more studies needed on this (issue)," Swan said. "But the implications (of the study) are potentially profound and far-reaching. And what strengthens our findings is they are consistent with rodent studies and with earlier studies...that found these phthalates lower testosterone."
But The American Chemistry Council (ACC) downplayed the study, saying Swan used "unproven methods" to reach conclusions that are "not based on the weight of the scientific evidence surrounding the safety of phthalates."
"People need to pay attention"
In Swan's study, researchers asked a group of mothers who previously had provided urine samples during their pregnancies, and whose children were in preschool, to answer questions about the play behaviors in their kids.
Researchers then examined the scores of the Pre-School Activities Inventory (PSAI) and other questions about the parents, their education, and their attitudes about their children's play.
"In these 145 preschoolers, born to mothers we had recruited when they were pregnant, we found that prenatal exposure to two phthalates -- DEHP and DBP -- was significantly associated with less masculine play behavior in boys," Swan said. "No other phthalate metabolites showed associations with boys' play behavior scores and no strong association was seen in girls for any phthalates."
Swan said examining the play behaviors in these boys was a natural follow-up to her previous study with this same group of moms.
In that 2005 study -- which many considered controversial at the time -- Swan found that pregnant women with higher levels of phthalates in their urine had sons with genital birth defects.
The boys, for example, were more likely to have "less fully" descended testicles, shorter or smaller penis size as measured by the volume, scrotums that were smaller and less distinct, and short anal-genital distances (AGD). Researchers say that measurement is an indicator of testosterone levels.
Prior to the 2005 study, scientists had linked phthalate exposure to malformed sex organs in male lab animals -- a condition known as "The phthalate syndrome" in rodents.
Neither of these studies, however, suggests a link between phthalates exposure in pregnant women and homosexuality, Swan pointed out.
"The question of homosexuality always comes up in connection with these studies," she told ConsumerAffairs.com. "And there is no data linking play toys (which ones a child chooses) or early behavior to later sexual preferences or sexual identity."
Asked why consumers should care about these latest findings, Dr. Swan said, "It's hard to say on an individual basis, but if you ask people if they care about ingesting a chemical that might make moms have sons with less masculine behaviors, they do care. This does matter to people because they call and ask me what they can do to avoid phthalate exposure."
Swan hopes consumers -- especially pregnant women or women thinking about get pregnant -- will walk away with two key messages from this new study.
"I want them to be aware that the fetus is not protected by placenta...that everything they do while they are pregnant has the potential to affect the fetus," said Swan. "Most women already know that, but what they may not know is the major source of phthalates is in processed foods. And people need to pay attention to how and what foods they buy, where they store them, and how they cook them to make them as phthalate-free as possible."
"More sensationalistic than scientific"
The ACC, however, said consumers shouldn't worry about phthalates, calling them "among the most thoroughly studied family of compounds in the world ... (with) a long history of safe use."
The organization also criticized Swan's findings and her research methods.
"This study shows once more that Swan uses unproven methods to compile questionable data to reach conclusions that are consistent with her well-publicized opinion, which is not based on the weight of the scientific evidence surrounding the safety of phthalates," said Steve Risotto, senior director of phthalate esters at the ACC.
"Dr. Swan's recognition that the study results are 'not straightforward' is an understatement," Risotto said. "The researchers biased the results by using mothers from their previous study. These mothers may have had much higher levels of concern about their young boys' behavior, because Swan has repeatedly declared that phthalate exposure is reason for alarm."
"It appears that the researchers selectively excluded data, eliminating certain subjects from the analysis, in order to strengthen their conclusion. Even the phraseology of the paper is more sensationalistic than scientific," he added.
"Doing the best science I can"
Swan isn't swayed by her critics.
"That is their job -- to protect their products," she told us. "I do the best science I can and I will keep doing the best science I can. And people will view it as they want."
Swan also said it's "unlikely" that her research is biased. The women in the group, she said, didn't know that phthalates were the focus of the study. They also didn't know their phthalate levels.
"We looked at a number of variables including parental age, education and their attitudes towards children's play," Swan explained. "In particular, we asked whether the mother would discourage a boy from playing with 'girl-typical' toys...all these were controlled for in our analysis.
"It is possible, however, that other uncontrolled factors could influence how the mother completed the questionnaire," she added, "but these are unlikely to be related to the mother's phthalate exposure."
Researchers at the Centers for Disease Control and Prevention, where phthalate metabolite levels were determined, also did not know the PSAI test results or any data about the women in the study, Swan said.
What about concerns that her findings are based on a small "focus group" of just 145 children?
"Sample size alone doesn't trump (a study's findings)," Swan said, adding federal officials have pulled drugs off the market based on the adverse reactions of just a few people.
Investigations into the developmental and neurological effects of prenatal phthalate exposure in humans are far from over, Swan said.
"We're funded to repeat the study from early pregnancy on," she said, adding that grants from the National Institute of Environmental Health Sciences and the US Environmental Protection Agency paid for her current study.
"We are going to recruit 800 women and follow those kids much better than with the first group. We'll be looking at neurological development and phthalate exposure and we'll also reconnect with our 145 children to see how they're doing at an older age."
"We're excited to be funded to do that and are glad the scientific community feels it's important."
Swan's next study will also measure other chemicals in the mothers' urine -- such as bisphenol-A -- to examine their effects on behaviors and development.
In the meantime, what advice does Swan offer consumers who are worried about their exposure to phthalates, which are now restricted from use in U.S. toys?
"Don't panic," she says. "When people ask me how they can reduce their risks from exposure to phthalates, which they often do, I tell them not to panic. If they want to take action, they can. That's an individual choice."
To reduce their exposure to these chemicals, Swan and other experts say consumers should:
• Avoid buying processed foods. According to U.S. News and World Report, one study found that prepared lunches had high levels of phthalates because food workers wore plastic gloves during the preparation.
• Avoid microwaving food in plastic containers.
• Look for cosmetics that are phthalate-free. Hair sprays, nail polish, deodorants, and other cosmetics contain phthalates, but the ingredients may only identify them as "fragrances."
• Limit children's exposure to soft plastic toys.
• Ventilate homes and offices. Many building materials and household items contain phthalates that experts say can get in the air and dust. Also keep vinyl tiles, imitation leather furniture, and other products that contain phthalate materials out of kids' rooms.
• Read labels. Many common household consumer products contain phthalates. Some companies, however, are advertising their phthlates-free stance, and have come out with toys and baby products that do not contain the chemicals.
Study Claims Phthalates Exposure In Pregnancy Diminishes Masculinity...