2013 BPA study has gone to the dogs: oral exposure doesn't increase BPA levels

Oral exposure to BPA does not lead to higher than expected levels of BPA in the blood, a new study has shown. This counters a 2013 study which found that placing concentrated BPA solutions under dogs’ tongues led to higher levels of an active form of BPA in the blood.

The authors of the dog study hypothesised that their results meant the amount of BPA in human blood could be higher than regulatory agencies assumed, leading to frequent and intense questioning of regulatory agencies’ BPA recommendations.

“Testing this hypothesis, in humans, became necessary,” said toxicologist Justin Teeguarden of the Department of Energy’s Pacific Northwest National Laboratory, author of the new study in humans.

Teeguarden and colleagues set out to determine if absorption of BPA from tissues of the mouth increased BPA blood levels in humans.

“Our goal was to mimic normal eating behaviour, assuring that the results of the study would apply to humans eating and drinking. This was something that was not possible in the dog study,” said Teeguarden.

To fully coat the oral cavity, 10 volunteers ate warmed tomato soup that contained a traceable form of BPA. Multiple blood and urine samples were taken over a 24-hour period.

The researchers found that this method of delivery did not lead to higher levels of the active form of BPA in the blood samples. The body inactivated 98 out of every 1000 BPA molecules by the time BPA entered the bloodstream. This has been reflected in all human studies to date.

“Just as important, we confirmed that there is no merit to hypotheses that BPA accumulates in humans. The entire dose of BPA was eliminated in urine within 24 hours, with no evidence of accumulation,” said Teeguarden.

“This latest study contributes new measurements in humans that confirm and extend the body of animal and human data and analyses establishing that BPA levels in human blood are even lower than those considered safe by regulatory agencies.

“Our study reinforces the accuracy of conclusions made by the European Food Safety Authority, the FDA, the World Health Organization and others about the extent and nature of BPA exposure, absorption and metabolism. It follows that if objective, evidence-based decisions are valued, regulatory agency determinations that BPA is safe as used for food contact applications are not challengeable on the basis of uncertainties in oral exposure.”

The study was published in the journal Toxicology and Applied Pharmacology.