Prenatal Pollutant Exposure Adversely Affects Child Behavior

Deborah Brauser

March 30, 2012

March 30, 2012 — Prenatal exposure to common urban air pollutants known as polycyclic aromatic hydrocarbons (PAHs) may lead to behavioral problems, including poor attention, anxiety, and depression, in young children, new research suggests.

In a follow-up study of children from the Columbia Center for Children's Environmental Health (CCCEH) cohort study, those who had prenatal exposure to PAHs were significantly more likely to have attention problems and symptoms of anxiety and depression by the age of 6 to 7 years than children who were not exposed to high levels of the pollutants.

Exposure levels were measured in both monitored air concentrations of PAH and a PAH biomarker assessed in maternal and umbilical cord blood.

"This study provides new evidence that prenatal exposure to air pollution at levels encountered in New York City adversely affects child behavior," principal investigator Frederica Perera, DrPH, professor at the Mailman School of Public Health at Columbia University in New York City and director of the CCCEH, told Medscape Medical News.

Dr. Frederica Perera

"The results are of concern because attention problems and anxiety and depression have been shown to affect children's academic performance and their relationships with peers," said Dr. Perera.

The study was published online March 22 in Environmental Health Perspectives.

Crosses the Placenta

PAHs are a common urban air pollutant that result from the incomplete combustion of fossil fuels, including diesel fuel, gasoline, oil used for heating purposes, and coal.

When inhaled by the mother during pregnancy, PAHs can be "transferred across the placenta" and bind to a fetus' DNA, forming adducts in blood and other tissues, according to the investigators in a release.

The ongoing CCCEH study originally enrolled 536 nonsmoking inner-city pregnant women who were between the ages of 18 and 35 years. All were black or Dominican-American.

"When we started this study over 12 years ago, there was little information on the role of prenatal exposures on later child health and developmental outcomes. So we decided to mount a study that was quite detailed in attempting to measure and record as many environmental exposures as we could," explained Dr. Perera.

"We included women who were nonsmokers because we did not want to be influenced by active smoking, which is a known risk factor for the outcomes of concern. Many were exposed to second-hand smoke, but we adjusted and controlled for that, as well as for lead and pesticides."

She noted that all of the participants were from the Northern Manhattan area of Washington Heights in New York City, where black and Dominican-American individuals make up the majority of the population.

Small backpack monitors measured the air to which the women were personally exposed during pregnancy. High levels of prenatal PAH exposure were defined as levels greater than 2.27 ng/m3.

DNA adducts specific to benzo[a]pyrene, a representative PAH, were also measured in both maternal and cord blood.

The children, who were born between 1999 and 2006, have been periodically assessed since birth.

Previously, the investigators published findings showing that prenatal exposure to PAH was associated with developmental delays by the time these children were 3 years of age. The researchers also found, as reported in Pediatrics, that the cohort was more likely to have reduced IQ by the age of 5 years.

Behavioral Symptoms

For this analysis, the researchers sought to examine 253 of the offspring when they were between the ages of 6 and 7 years.

The Child Behavior Checklist (CBCL) was administered to the mothers to assess behavioral symptoms of anxiety/depression and attention problems in their children. CBCL scales derived from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) were also used to measure anxiety and to assess for problems associated with attention-deficit/hyperactivity disorder (ADHD).

An investigator-administered questionnaire was also given to the mothers during the last trimester of pregnancy, at 6 months after giving birth, and annually after that. The questionnaire collected information on demographics, health, environment, and dietary PAH (which can include broiled, grilled, smoked, or fried meat).

Results showed that all of the mothers had detectable levels of PAH in their personal air samples.

However, children who were exposed to high levels of prenatal PAH, as shown on maternal personal air monitoring, had significantly higher adjusted scores for anxiety/depression (P < .0001) and for attention problems (P = .001) than children exposed to lower levels.

They also had significantly more DSM-IV-oriented anxiety problems (P = .009). There were no significant between-group differences in DSM-IV-oriented ADHD problems.

After adjusting for the summary scores of other environmental exposures measured (including bisphenol A, chlorpyrifos, and phthalates), the link remained significant between PAH and increased CBCL scores for anxiety/depression and attentional problems.

This link was also significant with regard to high vs low levels of PAH adducts in maternal blood (P = .019 for increased anxiety/depression scores; P = .003 for increased attention problems), as well as in cord blood (P < .001 for anxiety/depression scores; P = .002 for attention problems).

Need for Awareness

Dr. Perera reported that the investigators will continue following these children until they reach the age of 12 years.

"We hope to follow them right up through adolescence in order to get a full understanding of what the potential effects of these exposures might be, what emerges over time, and possible reversibility."

She suggested that parents living in urban settings should also be aware of their indoor environment. Steps could include not allowing people to smoke in the home, ventilating with a fan when cooking, avoiding exposure to other chemicals such as pesticides, and incorporating a healthy diet rich with fruits and vegetables. Other tips are available on the CCCEH Web site.

"I think clinicians should be aware of the information about these environmental pollutants and should provide helpful tips to their patients," concluded Dr. Perera.

The study was supported by the Educational Foundation of America, the John and Wendy Neu Family Foundation, the New York Community Trust, and Trustees of the Blanchette Hooker Rockefeller Fund, and by grants from the National Institute of Environmental Health Sciences and the US Environmental Protection Agency.

Environ Health Perspect. Published online March 22, 2012. Abstract



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