January 27th, 2010 
Prenatal exposure to ambient levels of flame retardant compounds called polybrominated diphenyl ethers (PBDEs) is associated with adverse neurodevelopmental effects in young children, according to researchers at the Columbia Center for Children’s Environmental Health (CCCEH) at Columbia University’s Mailman School of Public Health.
The study is online in Environmental Health Perspectives and will be released in the April 2010 print issue.
PBDEs are endocrine-disrupting chemicals and widely used flame-retardant compounds that are applied to a broad array of textiles and consumer products, including mattresses, upholstery, building materials, and electronic equipment. Because the compounds are additives rather than chemically bound to consumer products, they can be released into the environment. Human exposure may occur through dietary ingestion or through inhalation of dust containing PBDEs.
The researchers found that children with higher concentrations of PBDEs in their umbilical cord blood at birth scored lower on tests of mental and physical development between the ages of one and six. Developmental effects were particularly evident at four years of age, when verbal and full IQ scores were reduced 5.5 to 8.0 points for those with the highest prenatal exposures.
“The neurodevelopmental effects of prenatal exposure to PBDEs have not previously been studied among children in North America, where levels are typically higher than in Europe or Asia,” said Julie Herbstman, PhD, first author on the paper and a research scientist in Environmental Health Sciences at the Mailman School of Public Health. “The findings are consistent with effects observed in animal studies and, if replicated in other North American populations, they could have important public health implications.”
Frederica Perera, DrPh, professor of Environmental Health Sciences at the Mailman School, CCCEH Director, and coauthor added, “These findings are of potential concern, because IQ is a predictor of future educational performance; and the observed reductions in IQ scores are in the range seen with low level lead exposure.” This research underscores the need for preventive policies to reduce toxic exposures occurring in utero.”
The investigators controlled for factors that have previously been linked to neurodevelopment in other studies, including ethnicity, mother’s IQ, child’s sex, gestational age at birth, maternal age, prenatal exposure to environmental tobacco smoke, maternal education, material hardship, and breast feeding.
The study is part of a broader project examining the effects of chemicals released by the World Trade Center’s destruction on pregnant women and their children. However, residential proximity to the World Trade Center site did not affect levels of PBDE exposure.
Related
- Exposure to Tobacco Smoke Before Birth Affects DNA
Women who smoke while pregnant increase their unborn child’s long-term risk for health problems, including childhood asthma, cardiovascular disease and lower pulmonary function, and a new study may help experts understand why.
Researchers at the Keck School of Medicine of the University of Southern California (USC) found that maternal smoking actually changes the unborn child’s DNA patterns.
The new study found that fetal exposure to maternal smoking was linked to differences in DNA methylation, an epigenetic mechanism.
Epigenetics is the study of how chemicals that attach to DNA can switch genes on and off, which leads to differences in gene expression without changing basic genetic information, according to background information in a USC news release about the study.
While epigenetics plays a role in cancer research, little is known about how epigenetic changes may be caused by environmental exposures.
In the new study, the researchers used data from the USC Children’s Health Study, which examined respiratory health among children in 13 Southern California communities, as well as information from a questionnaire on maternal smoking exposure. The findings are reported in the September issue of the American Journal of Respiratory and Critical Care Medicine.
“This study provides some of the first evidence that in-utero environmental exposures such as tobacco smoke may be associated with epigenetic changes,” said one of the lead authors, Carrie Breton, assistant professor in the Department of Occupational and Environmental Health at the Keck School of Medicine of USC. “This could open up a new way for researchers to investigate biological mechanisms that might explain known health effects associated with maternal smoking,” she stated in the news release.
“Moms should not be smoking during pregnancy,” Linda Birnbaum, director of the U.S. National Institute of Environmental Health Sciences, said in the news release. “Maternal smoking during pregnancy is not only detrimental to the health of the mom and the newborn child, but research such as this suggests that it may impact the child into adulthood and possibly even future generations as well.”
- Flame Retardant May Up Risk of Thyroid Problems in Pregnancy
Exposure to flame-retardant chemicals may reduce a pregnant woman’s levels of certain thyroid hormones that play a critical role in fetal brain development, a new study shows.
Polybrominated diphenyl ether (PBDE) flame retardants are used in a large number of consumer products, including cars, electronics and home furnishings. PBDEs are found in the blood of most Americans, according to data collected by the U.S. Centers for Disease Control and Prevention.
In the new study, published online June 21 and in an upcoming print issue of the journal Environmental Health Perspectives, researchers from the University of California, Berkeley, measured thyroid hormone levels in 270 women, most of them Mexican-American, and found that those with higher PBDE levels had lower levels of thyroid-stimulating hormone.
Women with the highest levels of the flame retardant in their blood were more likely to have subclinical hyperthyroidism, which is defined as below-normal levels of thyroid-stimulating hormone with normal levels of the thyroid hormone thyroxine (T4), the researchers found.
“Women with low [thyroid-stimulating hormone] may be above their natural set-point for the T4 thyroid hormone, which means that their thyroids may not be functioning normally,” study author Jonathan Chevrier, of the Center for Children’s Environmental Health Research at University of California, Berkeley, said in a news release from the journal’s publisher.
“Elevated T4 in pregnancy has been associated with increased risks of miscarriage, premature birth and intrauterine growth retardation,” study co-author Brenda Eskenazi added.
“A mother’s thyroid hormones affect her developing baby throughout her pregnancy, and they are essential for fetal brain development,” Eskenazi, director of the Center for Children’s Environmental Health Research, stated in the news release.
- Use of Acetaminophen in Pregnancy Associated With Increased Asthma Symptoms in Children
Children who were exposed to acetaminophen prenatally were more likely to have asthma symptoms at age five in a study of 300 African-American and Dominican Republic children living in New York City. Building on prior research showing an association between both prenatal and postnatal acetaminophen and asthma, this is the first study to demonstrate a direct link between asthma and an ability to detoxify foreign substances in the body. The findings were published this week in the journal Thorax.
The study, conducted by the Columbia Center for Children’s Environmental Health at Columbia University’s Mailman School of Public Health, found that the relationship was stronger in children with a variant of a gene, glutathione S transferase, involved in detoxification of foreign substances. The variant is common among African-American and Hispanic populations. The results suggest that less efficient detoxification is a mechanism in the association between acetaminophen and asthma.
The researchers assessed the use of analgesics during pregnancy and found that 34 percent of mothers reported acetaminophen use during pregnancy, and 27 percent of children had wheeze, an asthma-related symptom. The children whose mothers had taken acetaminophen were more likely to wheeze, visit the emergency room for respiratory problems, and develop allergy symptoms, compared to those children whose mothers did not take acetaminophen. The risk increased with increasing number of days of prenatal acetaminophen use. The children in this study live in neighborhoods of New York City that have been the hardest hit by the asthma epidemic: Northern Manhattan and the South Bronx.
Acetaminophen use among children in the U.S. has increased substantially since the early 1980s and has become increasingly common among women during pregnancy so that most women in the U.S. take acetaminophen during pregnancy. This increase coincided with a doubling of the prevalence of asthma among children in the country between 1980 and 1995.
“These findings might provide an explanation for some of the increased asthma risk in minority communities and suggest caution in the use of acetaminophen in pregnancy,” says Matthew S. Perzanowski, PhD, assistant professor of Environmental Health Sciences at the Mailman School of Public Health.
Reasons for prenatal acetaminophen use vary, but in this study population the observed associations with headaches suggest pain management as likely; however, other host factors that caused mothers to take acetaminophen and also cause asthma may explain their association. While infection is one such potential confounder, the Mailman School researchers found no association between the reported use of antibiotics and acetaminophen, and adjustment for antibiotic use during pregnancy did not affect the results.
According to the researchers, the prevalence of current wheeze diminished as the children aged, from 40 percent at age one year to 25 percent, 17 percent and 27 percent at ages two, three, and five, respectively. However, the association between prenatal acetaminophen exposure and current wheeze strengthened as the children aged.
The Columbia Center for Children’s Environmental Health study adjusted relative risks for sex, race/ethnicity, birth order, maternal asthma, maternal hardship, exposure to environmental tobacco smoke, antibiotic use and postnatal acetaminophen use.
In a similar study conducted in the UK, the frequency of acetaminophen use during pregnancy and the magnitude of association in the UK study were similar to that in New York City.
- ADHD Linked to Lead and Cigarette Exposure During Pregnancy
Children whose mothers smoked during pregnancy or who were exposed to lead have more than double the risk of having attention-deficit hyperactivity disorder (ADHD) as other children, new research shows.
And with exposure to both cigarettes and lead, the chances of having ADHD soared. Children whose mothers smoked during pregnancy and whose blood showed signs of lead exposure had eight times the risk of having ADHD.
“When you have both exposures, there is a synergistic effect,” said study author Dr. Tanya Froehlich, a developmental and behavioral pediatric specialist and an assistant professor of pediatrics at Cincinnati Children’s Hospital Medical Center.
The researchers concluded that about 38 percent of ADHD cases among children aged 8 to 15 in the United States may be caused by prenatal exposure to tobacco smoke, while 25 percent of ADHD cases are due to lead exposure, according to the study in the Nov. 23 online issue of Pediatrics.
Froehlich and her colleagues used data on 2,588 children aged 8 to 15 from around the nation who took part in the 2001-2004 National Health and Nutrition Examination Survey. Tobacco exposure was assessed by asking mothers if they smoked during pregnancy, while lead concentrations were measured by a blood test.
About 8.7 percent of children met the criteria for ADHD, which is marked by inattentiveness, difficulty focusing, impulsivity and hyperactivity, according to the study. The ADHD group included 16.8 percent of children whose mothers smoked during pregnancy, compared to 6.6 percent of children whose mothers did not smoke.
Lead exposure was divided into three groups: low, medium and high. About 5.2 percent of children who had the lowest lead blood levels had ADHD. About 9.1 percent of children in the middle range had ADHD, while 13.6 percent of children in the highest third had ADHD, the researchers found.
About 28.6 percent of children who were exposed to both prenatal smoking and who had higher blood lead concentrations had ADHD, Froehlich said.
Researchers did not find a strong link between exposure to secondhand cigarette smoke during childhood and ADHD.
Alarmingly, even children in the upper third had lead exposure levels lower than what the federal government considers “elevated.” The U.S. Centers for Disease Control and Prevention considers levels of 10 micrograms per deciliter “actionable,” Froehlich said. In the study, children in the upper third had blood lead levels that were 1.3 micrograms per deciliter or greater; children in the middle group had levels between 0.9 and 1.3 micrograms per deciliter.
About 250,000 U.S. children aged 1 to 5 have blood lead levels greater than 10 micrograms of lead per deciliter of blood, according to the CDC. Though blood lead levels have generally dropped in recent years, children, particularly those in poor, inner-city neighborhoods, may still be exposed to lead from peeling paint in old buildings. Leaded paint was banned for most residential uses in the United States in 1978.
Children may also ingest lead from old water pipes, soil and toys. In the last few years there have been multiple recalls, some by major toy manufacturers such as Mattel and Fisher-Price, of products manufactured in China that contained unsafe levels of lead.
“Lead is out there, and we need to take precautions, such as making sure we keep kids away from peeling paint and make sure they practice good hand washing before they eat if they are playing in the soil,” Froehlich said.
In addition, good nutrition, including making sure children have adequate levels of iron and calcium, can also protect from lead exposure. Children with iron and calcium deficiencies absorb more lead than children with better diets, Froehlich explained.
- ADHD Linked to Lead and Cigarette Exposure During Pregnancy
Children whose mothers smoked during pregnancy or who were exposed to lead have more than double the risk of having attention-deficit hyperactivity disorder (ADHD) as other children, new research shows.
And with exposure to both cigarettes and lead, the chances of having ADHD soared. Children whose mothers smoked during pregnancy and whose blood showed signs of lead exposure had eight times the risk of having ADHD.
“When you have both exposures, there is a synergistic effect,” said study author Dr. Tanya Froehlich, a developmental and behavioral pediatric specialist and an assistant professor of pediatrics at Cincinnati Children’s Hospital Medical Center.
The researchers concluded that about 38 percent of ADHD cases among children aged 8 to 15 in the United States may be caused by prenatal exposure to tobacco smoke, while 25 percent of ADHD cases are due to lead exposure, according to the study in the Nov. 23 online issue of Pediatrics.
Froehlich and her colleagues used data on 2,588 children aged 8 to 15 from around the nation who took part in the 2001-2004 National Health and Nutrition Examination Survey. Tobacco exposure was assessed by asking mothers if they smoked during pregnancy, while lead concentrations were measured by a blood test.
About 8.7 percent of children met the criteria for ADHD, which is marked by inattentiveness, difficulty focusing, impulsivity and hyperactivity, according to the study. The ADHD group included 16.8 percent of children whose mothers smoked during pregnancy, compared to 6.6 percent of children whose mothers did not smoke.
Lead exposure was divided into three groups: low, medium and high. About 5.2 percent of children who had the lowest lead blood levels had ADHD. About 9.1 percent of children in the middle range had ADHD, while 13.6 percent of children in the highest third had ADHD, the researchers found.
About 28.6 percent of children who were exposed to both prenatal smoking and who had higher blood lead concentrations had ADHD, Froehlich said.
Researchers did not find a strong link between exposure to secondhand cigarette smoke during childhood and ADHD.
Alarmingly, even children in the upper third had lead exposure levels lower than what the federal government considers “elevated.” The U.S. Centers for Disease Control and Prevention considers levels of 10 micrograms per deciliter “actionable,” Froehlich said. In the study, children in the upper third had blood lead levels that were 1.3 micrograms per deciliter or greater; children in the middle group had levels between 0.9 and 1.3 micrograms per deciliter.
About 250,000 U.S. children aged 1 to 5 have blood lead levels greater than 10 micrograms of lead per deciliter of blood, according to the CDC. Though blood lead levels have generally dropped in recent years, children, particularly those in poor, inner-city neighborhoods, may still be exposed to lead from peeling paint in old buildings. Leaded paint was banned for most residential uses in the United States in 1978.
Children may also ingest lead from old water pipes, soil and toys. In the last few years there have been multiple recalls, some by major toy manufacturers such as Mattel and Fisher-Price, of products manufactured in China that contained unsafe levels of lead.
“Lead is out there, and we need to take precautions, such as making sure we keep kids away from peeling paint and make sure they practice good hand washing before they eat if they are playing in the soil,” Froehlich said.
In addition, good nutrition, including making sure children have adequate levels of iron and calcium, can also protect from lead exposure. Children with iron and calcium deficiencies absorb more lead than children with better diets, Froehlich explained.
