No, BPA Levels in Humans Have Not Been Dramatically Underestimated

Steven Hentges, Ph.D
Wednesday, December 11, 2019

SAFETY

Well over 100 biomonitoring studies conducted worldwide have consistently demonstrated
that human exposure to BPA is extremely low and well within safe exposure limits. Now
a new, small-scale study suggests that human exposure to BPA has been “dramaticallyunderestimated.” Regrettably, the study has been misinterpreted in the media, turning it into
the “scare story” du jour.
This might be news if it was true, but is it, and how do we know? It has been well-known formany years that BPA is efficiently converted in the body after exposure to a biologicallyinactive metabolite, which is then rapidly eliminated from the body in urine. Biomonitoringstudies rely on these physiological processes to measure exposure to BPA using wellestablished analytical methodology.
More specifically, the metabolite of BPA that is eliminated in urine is converted in thelaboratory with the aid of an enzyme back to BPA itself, which is then easily measured withsensitive analytical instruments. Exposure to BPA (i.e., how much BPA goes into the body)is readily determined by how much BPA comes out of the body in urine.
In the new study, the authors were unsuccessful in implementing this well-establishedmethodology in their laboratory. They claim that the enzymatic reaction doesn’t actuallywork that well, with the result that much of the BPA metabolite in urine is overlooked. If thisis true, exposure to BPA would be underestimated.
The authors then suggest that the U.S. Food and Drug Administration (FDA) and the U.S.
Centers for Disease Control and Prevention (CDC) failed to properly validate the analytical
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method. Surprisingly though, after pinning the blame on FDA, the authors make no mentionof the extensive research published by FDA and others that conclusively demonstrates theanalytical method is, in fact, valid and reliable.
Of particular note are two studies conducted jointly by FDA with the U.S. National
Toxicology Program and with the Pacific Northwest National Laboratory. In each study,
human volunteers were dosed with a measured amount of BPA. Urine from the volunteers
was collected after exposure and analyzed in FDA’s laboratory with the well-establishedanalytical method.
In both of these studies, the dose of BPA administered to the volunteers was quantitatively
recovered in urine, demonstrating conclusively that the analytical method is valid and does
not underestimate BPA. Similar results were published more recently in a study fromresearchers at the University of Alberta and Stockholm University, and earlier in two studies
from researchers at the University of Würzburg and in a study from researchers at
the Bavarian Health and Food Safety Authority.
In each of these studies, any discrepancy in the analytical method would have been
obvious since the human volunteers were dosed with known amounts of BPA. In eachcase, the known dose was quantitatively found in urine, which demonstrates that theanalytical method accurately measures exposure to BPA. These studies provide strong
reassurance that the results of biomonitoring studies that rely on this methodology
accurately measure human exposure to BPA.
In spite of the scary headlines generated by the new study, there is no cause for alarm. As
demonstrated by more than 100 biomonitoring studies worldwide, using a valid analyticalmethod, human exposure to BPA is extremely low and well within safe limits.

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