Possible Link Between ADHD and Common Chemicals, PFCs
Researchers are suggesting yet another link between chemicals in the environment and attention deficit hyperactivity disorder (ADHD). Boston University School of Public Health experts report that high levels of polyfluoroalkyl chemicals (PFCs) have been found in some children who have ADHD.
Previously, a study published in November 2009 in Biological Psychiatry reported a positive association between phthalate levels, a chemical found in common products such as toys, cleaning supplies, and personal care items, and ADHD. Another recent study named lead as a possible cause of ADHD. Yet another report, this one published in Pediatrics, has linked pesticides known as organophosphates to ADHD.
Now experts have found “increased odds of ADHD in children with higher serum PFC levels.” The study involved data from the National Health and Nutrition Examination Survey (NHANES) and compared the PFC levels in serum samples from 586 children age 12 to 15. Fifty-one of these children had a diagnosis of ADHD.
According to a study conducted by the Centers for Disease Control and Prevention (CDC), PFCs have been used since the 1950s, and exposure of the general public is widespread. Polyfluoroalkyl chemicals are used in industrial applications and can be found in products such as stain-resistance coatings, fire fighting foams, and food packaging.
The CDC study, which was published in 2007, found that more than 98 percent of the general population had detectable serum levels of PFCs. Once PFCs are absorbed by the body, they can take years to be partially eliminated. There are many different types of PFCs, including but not limited to perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PROA), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS), which are the four evaluated by the researchers in the Boston study.
According to Kate Hoffman, lead author of the Boston University team of investigators, “there’s a link between this exposure and outcome but we’re not really sure what way that goes.” At this point, experts can report that “children with this outcome tend to have higher levels of PFCs in their blood.”
One reason investigators looked at PFCs and ADHD is because animal studies have suggested that exposure to these chemicals can have neurotoxic effects. ADHD is a common neurodevelopmental disorder that is strongly suspected to be associated with environmental factors. Further research is needed to determine the effect of PFCs on ADHD and other neurodevelopmental conditions.
Calafat AM et al. Environmental Health Perspectives 2007 Nov; 115(11): 1596-602
Hoffman K et al. Environmental Health Perspectives 2010; DOI: 10.1289/ehp.1001898