Metabolism in Humans - 24-Hour Human Urine and Serum Profiles of Bisphenol A During High Dietary Exposure

Author: Teeguarden et al. (2011)

Publication: Toxicological Sciences

Date: June 24, 2011

exposure metabolism

This EPA-funded study, conducted by scientists at the Pacific Northwest National Laboratory, FDA and CDC, assessed blood and urine concentrations of BPA in healthy adults who had consumed a controlled diet including high levels of canned foods likely to be significant sources of BPA. Consistent with previous human and animal studies, the results of this study confirmed that BPA is efficiently converted to a biologically inactive metabolite and rapidly excreted in urine.

Illustrating the efficiency of this metabolic process, no un-metabolized or biologically active BPA was detected in the bloodstream of any participant at any time point in the study even when the volunteers ingested much higher amounts of BPA than a typical person in daily life. Only the inactive metabolite of BPA was transiently found at low levels before it was eliminated from the body.

Importantly, results indicated that, because of the efficient way BPA is processed in the body, it is very unlikely that BPA could cause health effects as the estimated maximum levels of BPA in blood in this study are 1 to 3 orders of magnitude below levels that have been linked to potentially adverse effects in the most sensitive of animal tests. For more information, please click here.

In addition, based on their results, the authors note that reported high levels of BPA in blood found in other studies are unlikely to be valid, and that contamination of the test samples has likely been the cause of high levels of free BPA reported by smaller-scale studies.

At a Glance

What was tested?
This EPA-funded study, conducted by scientists at the Pacific Northwest National Laboratory, FDA and CDC, assessed blood and urine concentrations of BPA in healthy adults who had consumed a controlled diet including high levels of canned food likely to be significant sources of BPA.
Findings
Illustrating the efficiency of the normal metabolism of BPA, no un-metabolized or biologically active BPA was detected in the bloodstream of any participant at any time point in the study even when the volunteers ingested much higher amounts of BPA than a typical person in daily life. Only the inactive metabolite of BPA was transiently found at low levels before it was eliminated from the body.
Study Limitations
Authors note that "The volunteers in the current study ingested large volumes of water to ensure the feasibility of regular urine collections, raising the possibility that high urine volumes could shift [BPA] concentrations toward undetectable levels in urine. However, [BPA] was detected in 74% of urine samples, providing more than sufficient information" to estimate total daily exposure.
Importance
Results indicated that, because of the efficient way BPA is processed in the body, it is very unlikely that BPA could cause health effects as the estimated maximum levels of BPA in blood in this study are 1 to 3 orders of magnitude below levels that have been linked to potentially adverse effects in the most sensitive of animal tests. In addition, based on their results, the authors note that reported high levels of BPA in blood found in other studies are unlikely to be valid, and that contamination of the test samples has likely been the cause of high levels of free BPA reported by smaller-scale studies.