The scientific discussion about the food contact substance bisphenol A (BPA) has lately been shaped by opposing positions on whether free, active BPA is present in human blood. On one hand, BPA is thought to be rapidly metabolized from the human body with no free BPA circulating in the blood system. Such rapid clearance of BPA has been shown in scientific publications. Yet, several studies have reported free BPA in human serum samples from biomonitoring studies. Subsequently, these findings have been questioned by experts and criticized as systematic errors or artifacts.

A blinded “round robin” study funded by the U.S. National Institutes of Environmental Health Sciences (NIEHS) aimed to shed light on these conflicting scientific points of view. The study was carried out by 5 U.S. labs with analytical chemistry competence for detecting both the free BPA (aglycone BPA) as well as the inactive metabolism-product BPA-glucuronide (glycone BPA). All materials coming into contact with human blood samples were first tested for their BPA leaching. Indeed, some materials were found to release the chemical, and were subsequently excluded from the sampling protocol. Blood samples were then collected and analyzed by all participating laboratories using verified BPA-free sampling materials. Irrespective of the careful selection of BPA free sampling materials, free BPA was detected in some samples at low levels.

The study will be published later this year, together with other findings from the NIEHS/FDA joint BPA study that has been on-going since 2009 (FPF reported previously). Results were presented by Laura Vandenberg of Tufts University at the recently held Copenhagen workshop on endocrine disrupters, 28-31 May 2013, Denmark.