Ask Carl Winter, PhD, Extension food toxicologist at the University of California, Davis, to name the event that brought bisphenol A (BPA) to the forefront of public awareness and he is quick to mention a feature article published in the December 2009 issue of Consumer Reports.
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Said article presented results of a limited monitoring program that detected BPA in several of the 19 name-brand foods tested. “While the findings were predictable, the article drew national headlines with its contention that consumers could be facing serious risks from exposure to BPA in their foods,” Dr. Winter points out.
Synthesized in 1891 by Russian chemist Aleksandr Dianin, BPA is a chemical now used primarily in the production of polycarbonate plastics and epoxy resins. Polycarbonate plastics are used in food and drink packaging, while resins are employed as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes.
According to Dr. Winter, the controversy in 2009 stemmed from the debate over what levels of consumer exposure to BPA should be of concern. “The U.S. Environmental Protection Agency (EPA) and the European Food Safety Authority (EFSA) then considered an acceptable level of BPA exposure to be 50 micrograms (μg) per kilogram (kg) of body weight per day (μg/kg/day),” he notes. “In contrast, the Consumer Reports article argued for an acceptable level of 0.0024 μg/kg/day, which was more than 20,000 times lower than the U.S. and European levels.”
Today much of the ongoing concern regarding BPA exposure to consumers is based upon the scientific process of “hazard identification,” as contrasted with “risk characterization,” Dr. Winter relates.
“Hazard identification expresses what is known about the chemical in question (BPA in this example) and what potentially hazardous properties it may have, such as estrogenic, carcinogenic, or neurotoxic properties that could be revealed from animal toxicology studies or human epidemiology,” he explains. “Hazard identification does not consider the amounts of actual exposure to the chemical in question. In contrast, risk characterization identifies the most significant and relevant toxicological endpoints (results of studies conducted to determine how dangerous substance are), identifies toxicologically-significant levels of concern, and compares predicted levels of exposure with the levels of concern to estimate how risky the chemical is.”
The FDA issued a memo in 2014 concluding that estimated exposures to BPA among a variety of population subgroups were more than 4,000 times lower than the 5 μg/kg/day level of toxicological concern for BPA.
Following that FDA memo, the regulatory limits have dropped from 50 μg/kg/day to 4 or 5 μg/kg/day since June 2014 “primarily because of the use of an additional 10-fold uncertainty factor conservatively applied to risk characterization process,” Dr. Winter says.
“Similar conclusions were reported in 2015 by the EFSA, which uses a slightly lower level of toxicological concern, 4 μg/kg/day, but still concludes that exposures, including dietary and non-dietary, for all population subgroups were below this level,” he adds.
In 2012, the U.S. National Toxicology Program, the National Institute of Environmental Health Sciences, and the FDA developed a research program called Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA). “CLARITY-BPA recently concluded a two-year BPA toxicological Core Study and the results, currently being peer reviewed and expected to be published in August 2018, could affect the level of toxicological concern for BPA,” Dr. Winter predicts. “It would take a significant reduction in the level of toxicological concern for authorities such as the EPA, FDA, or the EFSA to change their conclusions regarding the lack of risk posed by BPA to consumers based upon exposure characteristics.”
FDA’s current position on BPA is reflected in a recent statement by Stephen Ostroff, MD, Deputy Commissioner for Foods and Veterinary Medicine, in which he mentions that the CLARITY-BPA Core Study found “minimal effects” for the BPA-dosed groups of rodents when growth, weight, and tumor development were evaluated.