Early life exposure to bisphenol A (BPA) may be linked to an increased risk for the development of several types of behavior problems, new research suggests.
A study of almost 292 participants showed that prenatal exposure to BPA, as measured in maternal urine tests, was associated with internalizing behaviors, such as anxiety and depression, in the boys at the age of 7 years — but not in the girls.
However, early childhood BPA concentrations were associated with increased externalizing behaviors, such as conduct problems, in the girls. Childhood urine measurements of BPA were also linked to the internalizing behaviors of inattention and hyperactivity in both sexes.
"I'd say the take-away is that exposure to BPA, such as in hard plastic containers or canned foods, should be avoided if possible," coinvestigator Robert B. Gunier, data analyst and PhD candidate at the Center for Environmental Research and Children's Health in the School of Public Health at the University of California, Berkeley, told Medscape Medical News.
"There have been a few studies now that have shown very similar results, as far as the internalizing behaviors in children. Although a single study can't prove any relationship like this between environmental exposures, there have now been a few that are fairly consistent," said Gunier.
The study was published online July 17 in Environmental Research.
BPA is "an endocrine disrupting chemical used in some food and beverage containers, receipts, and dental sealants, [and] has been associated with anxiety and hyperactivity in animal studies," write the researchers.
They add that although some human studies have shown that early life exposure to BPA may be linked to behavior problems in children, specific results have been mixed — including what role the different sexes may play.
The ongoing Center for the Health and Assessment of Mothers and Children of Salinas (CHAMACOS) study was started in 1999 to assess environmental exposures in 601 pregnant women who were living in an agricultural area of California.
"This study started off primarily to examine pesticide exposures in this farm-working community. Since then, the study has branched out to look at other chemicals, such as flame retardants and BPA," said Gunier.
For this analysis, the investigators evaluated data on the CHAMACOS study participants (98.6% Latina, 4% other), as well as on 292 of their children.
During pregnancy, maternal urine samples were collected and measured for BPA concentrations. Urine samples were also collected from the offspring at 5 years of age.
When the children were 7 years of age, their mothers and teachers filled out the Behavior Assessment System for Children 2 (BASC-2) and the Conners' ADHD/DSM-IV Scales (CADS).
When assessing prenatal exposure to BPA, the researchers found that the boys who had been exposed to higher concentrations had increased internalizing problems, according to scores on the BASC-2.
In fact, each doubling of concentration was linked to an increase in internalizing scores by 1.8 points (95% confidence interval [CI], 0.3 - 3.3; P < .05) and 2.5 points (95% CI, 0.7 - 4.4; P < .01) on the BASC-2 maternal and teachers' reports, respectively.
Higher concentrations were also associated with increased symptoms of depression and anxiety in the boys, according to both the mothers' (1.5 for both symptom types) and teachers' reports (3.2 and 1.9, respectively).
A link was also found with increased aggressive behavior, but only on the teachers' report. There were no associations found between prenatal exposure to BPA and scores on the CADS.
There were also no associations found between prenatal exposure levels and any types of behavior problems in girls, as measured on the BASC-2 and CADS.
BPA exposure during childhood, as measured by urine tests when the children were 5, was strongly linked to inattention and hyperactivity in both the boys and girls.
However, a link between BPA childhood exposure and conduct problems was only found in the girls.
"This study adds to the limited and somewhat conflicting data on the effects of prenatal and postnatal BPA exposure on children's neurobehavioral development," write the investigators.
They note that because of "considerable inconsistencies" in the literature, especially with regard to timing of the exposure and the effect of one sex over the other, other measures of BPA exposure are sorely needed.
Gunier reported that the investigators are also continuing to evaluate other possible environmental exposures in these children, including manganese and polybrominated diphenyl ethers (PBDEs).
"We'll continue to look at behavior and neurodevelopment in the children. The cohort is now averaging 12 years of age, so we're starting to look at the onset of puberty and whether the chemical exposures are altering this onset — making it earlier or later," he explained.
The study was funded by grants from the National Institute of Environmental Health Sciences and from the United States Environmental Protection Agency. The study authors have disclosed no relevant financial relationships.
Environ Res. Published online July 17, 2013. Abstract
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Cite this: Early BPA Exposure Linked to Depression, Inattention in Kids - Medscape - Aug 07, 2013.