A study in Cincinnati, Ohio has shown evidence that polybrominated diphenyl ether (PBDE), a flame retardant compound, may act as a developmental neurotoxicant in children whose mothers were exposed to the substance.
This finding is consistent with two other U.S. birth cohort studies conducted in New York and California. In all three studies, the children’s IQ scores were shown to be inversely influenced by the level of their mothers’ PBDE exposure.
Between the 1970s and 2004, polybrominated diphenyl ether was commonly used in the manufacture of furniture, carpeting, padding and electronic devices. Because of various and alarming human health concerns, the penta- and octa-BDE forms were banned by the European Union in August 2004. The deca-BDE form was also phased out in 2006.
In the U.S., production of penta- and octa-BDEs ceased in 2004 due to a voluntary phase-out by manufacturers, though as of this writing no federal ban on these chemicals exists. And today, “pretty much everyone still has penta- and octa-containing products in their home,” says Julie Herbstman of Columbia University, lead author of the New York study.
Studies have shown exposure to PBDEs carries the risk of liver, thyroid and neurodevelopmental toxicity. The prevalence of these chemicals makes it very easy for them to accumulate in the body over time through ingestion, inhalation and dermal absorption of house dust.
The Cincinnati research was conducted on 309 women who were pregnant between 2003 and 2006. At 16 weeks’ gestation, a blood sample was obtained from each. All mothers had detectable levels of BDE-47, a common congener, or ingredient, in PBDE.
The children in the study underwent yearly developmental and behavioral assessments through the age of five. After these tests, researchers report a 4.5 reduction in children’s IQ scores for mothers with a 10-fold increase in BDE-47 concentrations. Such exposure was also associated with a 3.3-point increase in hyperactivity.
“What’s really important is the consistency in the results across three very different populations, [which is] pretty amazing,” says Linda Birnbaum, director of the National Institute of Environmental Health Sciences, referencing the earlier California and New York studies.
A coauthor of the Cincinnati study, Bruce Lanphear, says a reduction in IQ scores could be disastrous for the U.S. economy. A 5-point decline in the average I.Q. of American children would result in an additional 3.4 million children born intellectually disabled or mentally challenged. The costs of treatment, special education and lost lifetime earnings would quickly add up.
“There isn’t a published estimate of the cost of PBDE toxicity,” says Lanphear, “but based on what we know about the impact and costs of lead toxicity, I would expect the cost of PBDEs to exceed $10 billion annually in the United States.”