Scientists from the University of Missouri found there was an increased absorption and accumulation of BPA in the blood of mice when they were given repeated doses of the chemical as a regular dietary supplement – compared to the more common lab method of a single larger exposure.
The study - Comparison of Serum Bisphenol A Concentrations in Mice Exposed to Bisphenol A through the Diet versus Oral Bolus Exposure by Cheryl Rosenfeld et al – said that the method it used more closely reflected the way in which humans were exposed to BPA and was more likely to mirror real absorption and accumulation patterns.
In the research, published in the journal Environmental Health Perspectives, mice were continuously exposed to the substance in their feed – the acknowledged primary route for human and animals to BPA – over a period of seven days.
Rosenfeld, an associate professor in biomedical sciences, said this resulted in a significant increase in the active form of BPA that was absorbed and accumulated in the body of mice. This active form is a greater threat as it can bind to sex steroid receptors and cause adverse side effect, said the study.
"People are primarily and unknowingly exposed to BPA through the diet because of the various plastic and paper containers used to store our food are formulated with BPA," said Rosenfeld. "We know that the active form of BPA binds to our steroid receptors, meaning it can affect oestrogen, thyroid and testosterone function. It might also cause genetic mutations. Thus, this chemical can hinder our ability to reproduce and possibly cause behavioural abnormalities that we are just beginning to understand."
Conversely, a single large dose “may not only underestimate exposure to bioactive BPA in serum but also lead to inaccurate conclusions concerning long term concentrations of active BPA in serum or plasma of animals and humans”, said the study.
Rosenfeld added: "When BPA is taken through the food, the active form may remain in the body for a longer period of time than when it is provided through a single treatment, which does not reflect the continuous exposure that occurs in animal and human populations.”
More research was necessary to determine where the ingested BPA becomes concentrated and subsequently released back into the bloodstream to be distributed throughout the body, said the associate professor.
Comparison of Serum Bisphenol A Concentrations in Mice Exposed to Bisphenol A through the Diet versus Oral Bolus Exposure by Paizlee T. Sieli, Eldin Jašarević, Denise A. Warzak, Jiude Mao, Mark R. Ellersieck, Chunyang Liao, Kurunthachalam Kannan, Séverine H. Collet, Pierre-Louis Toutain, Frederick S. vom Saal, Cheryl S. Rosenfeld