A new environmental toxicity study from Harvard School of Public Health (HSPH) and the University of Copenhagen has found that exposure limits set by the U.S. Environmental Protection Agency (EPA) and other agencies for perfluorinated compounds (PFCs) found in drinking water appear to be 100 to 1,000 times too high. PFCs are chemicals widely used in manufactured products such as non-stick cookware, waterproof clothing, and fast-food packaging.
[[Philippe Grandjean]], adjunct professor of environmental health at HSPH, and Esben Budtz-Jørgensen of the University of Copenhagen, concluded that current exposure limits do not adequately protect children and other vulnerable groups against adverse effects on the human immune system. These same researchers showed in 2012 that routine childhood vaccines are less effective in children exposed to PFCs.
The new study, “Immunotoxicity of perfluorinated alkylates: Calculation of benchmark doses based on serum concentrations in children,” was published online April 18, 2013, in the BioMed Central open access journal Environmental Health.
The researchers compared blood concentration levels of PFCs for 431 five-year-olds in a birth cohort to serum antibody concentrations against tetanus and diphtheria toxoids in the same children at age 7. A doubling in PFC exposure was associated with a 50% decrease in the antibody concentration. As a threshold for this effect could not be identified, the researchers calculated a so-called benchmark dose to identify approximate exposure levels that would protect against the effect. The same method is used by EPA and other agencies.
“Most of the research on PFCs is fairly recent. So it’s no surprise that the EPA limits are already outdated. But if they are more 100 times too high, we need to discuss what went wrong and why the limits were so far off,” Grandjean said.
According to the authors, the discrepancy between the current safe levels and the tolerable exposure levels identified in the new study has occurred because PFCs have not been subjected to systematic toxicity testing, as they were ‘grandfathered’ in when the Toxic Substances Control Act (TSCA) was enacted in the U.S. in 1976. Although production of one of the compounds studied, PFOA (or C8), is currently being phased out in the U.S. and production of another (PFOS) has stopped, exposures continue due to the persistence of these compounds in the environment and in consumer products, and their continued production in other countries.
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