(There are some toxicology topics of which we should be aware. One of them is the debate regarding the toxicity of BPA which has now resulted in BPA analogs (of which we know even less than we do about BPA) replacing BPA.)
Bisphenol A (BPA) is a chemical used in the manufacture of polycarbonate plastics ( plastic dinnerware, microwave ovenware, eyeglass lenses, toys, pacifiers etc), epoxy resins (protective linings of canned food and beverage containers, wine vat linings, some dental composites etc), as a dye developer in thermal paper (cash register receipts, medical technical paper), and as a polymerization inhibitor in the formation of some polyvinyl chloride plastics.
BPA leeches out of the containers and into the contents of the container. Consequently, human exposure is widespread. BPA has been detected in the urine of 92% of participants surveyed in the United States National Health and Nutrition Examination Survey (NHANES) in 2003–2004 (Calafat et al., 2008). The toxicity of BPA is unknown. BPA has been reported to cause a wide range of adverse health outcomes in experimental animal studies; similar findings in humans have also been linked to BPA exposure in observational epidemiology studies (not good data on which to determine cause and effect).
BPA is an estrogenic compound with a similar structure to the estrogen receptor (ER) agonist, diethylstilbestrol (DES). BPA is considered an endocrine disrupter. The Environmental Protection Agency (U.S. EPA) defines an endocrine disrupter as” an exogenous agent that interferes with the synthesis, secretion, transport ,binding, action, or elimination of natural hormones in the body which are responsible for the maintenance or homeostasis, reproduction, development and/or behavior”.
The ubiquitous presence of BPA in the environment has raised concerns that BPA plays a role in carcinogenesis. But without xenobiotic disposition data, human health risk assessments cannot be determined.
Today at least 12 US states and the District of Columbia have placed restrictions on BPA.
Scientists and regulatory agents continue to debate the hazards of BPA. Regulatory and legislative actions have eliminated some of the uses of BPA. To replace BPA, numerous structural analogs have been introduced in commerce. These analogues (now also found in the environment) are also endocrine disruptors. We have very little information about their toxicity.
The question of the week was prepared by Donna Seger, MD