Prenatal Exposure to Common Chemicals Linked to Lower IQs in Study
Children's IQs were about 7 points lower among mothers with the highest exposures
WEDNESDAY, Dec. 10, 2014 (HealthDay News) -- Children exposed in the womb to higher amounts of two chemicals commonly found in plastics may be at higher risk for lower IQ, a new study suggests.
The two compounds, di-n-butyl phthalate (DnBP) and di-isobutyl phthalate (DiBP), are part of a class of chemicals called phthalates and are found in a variety of household goods.
"This study adds to the small but growing body of research linking children's prenatal exposure to phthalates and later development," said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Cohen Children's Medical Center of New York, who was not involved with the study. "This is the first prospective study to identify an association between prenatal phthalate exposure and IQ in school-age children."
Phthalates are added to plastics to make them more flexible and harder to break, according to the U.S. Centers for Disease Control and Prevention. But they serve other purposes as well, said study author Pam Factor-Litvak, an associate professor of epidemiology at the Columbia University Medical Center in New York City.
"Depending on the specific phthalate, they are used to make plastic flexible, as adhesive and as additives to cosmetics, air fresheners and cleaning products, as several 'hold' scents," Factor-Litvak said.
Factor-Litvak and her colleagues gave IQ tests to 7-year-old children of 328 inner-city mothers whose urine had been tested for phthalates exposure during late pregnancy.
The children of women in the highest quarter of exposure to DnBP and DiBP had IQs an average seven points lower than children of mothers in the lowest quarter of exposure, the investigators found.
The children also had poorer processing speed, perceptual reasoning and working memory if they were exposed to higher levels of these two chemicals, the findings showed. Perceptual reasoning refers to a person's ability to visualize and understand non-verbal information. In addition, verbal comprehension was lower among children with the greatest exposure to DiBP.
The researchers had also looked at exposure to three other phthalates -- butylbenzyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP) and diethyl phthalate (DEP) -- but did not see any differences among the children, with the exception of lower perceptual reasoning linked to BBP exposure. The findings were published Dec. 10 in the journal PLOS ONE.
"Although we cannot conclusively deduce that phthalates are responsible for the adverse effects on children's development, the growing body of research certainly suggests that phthalates may not be as safe as previously thought and that steps should be taken at a national level to reduce exposure to these chemicals," Adesman said.
Congress has already banned three phthalate types when they occur in concentrations greater than 0.1 percent in children's toys and specific child care articles, according to Factor-Litvak. Those include BBP, DEHP and dibutyl phthalate (which includes DiBP and DnBP), all of which were studied in this paper.
"While these regulatory actions were taken to protect young children, there have been no regulatory actions to protect the developing fetus in utero, which is often the time of greatest susceptibility," Factor-Litvak noted. "There are some replacement compounds on the market, but to our knowledge, they have not been studied extensively."
Factor-Litvak said it's difficult for individuals to completely avoid exposure to phthalates since the compounds are so widely used in consumer products, but there are steps people can take to reduce their exposures.
"Avoid microwaving food in plastic and avoid scented products, such as cleaning supplies, air fresheners and personal care products as much as possible," Factor-Litvak said. "Avoid use of plastics labeled as #3, #6 and #7 as these contain phthalates as well as BPA (bisphenol A), and store food in glass rather than plastic containers as much as possible."
Adesman pointed out that the 2013 CDC fact sheet on phthalates states that human health effects from exposure to low levels of phthalates are unknown.
"Several studies now suggest that there may be adverse effects on children from prenatal phthalate exposure," Adesman said. "The CDC needs to encourage more research in this area and consider revising these fact sheets to reflect recent research. Likewise, the government should consider mandating changes to product labels to indicate which products have phthalates and/or consider restrictions on which types of products can include phthalates."
Visit the U.S. Centers for Disease Control and Prevention for more on phthalates.