March 1 2013
Yet another study has come out on the alleged adverse health effects of the chemical Bisphenol A (BPA)—which is used to make clear, hard plastics and resins that line food containers. This one suggests that BPA impacts babies’ neurological development in the womb. But like so many of the studies on the topic, this paper suffers from some serious flaws that make its conclusions highly questionable.
A recent article published on an Australian news site, The Conversation, highlights some the study’s serious flaws, as noted by scientists on the Australian Science Media Center. Here are some highlights:
Emeritus Professor Michael Moore: “Short-term ‘in vitro’ experiments of the type seen in this study of provide valuable pointers towards probable mechanisms that might be observed in humans but are two steps removed from proof of causation of disease.”
Dr Ian Musgrave: “This is a very interesting study. Unfortunately, it’s linkage to environmental exposure to Bisphenol A is misleading, in that the concentrations used in this study are hundreds to thousands of times higher than humans would be exposed to through the maximal permissible level of BPA in food.”
Professor Andrew Bartholomaeus: “This study seeks to identify a mechanism for effects that have not been demonstrated to occur, using a method that is not relevant to the normal route of exposure. More specifically, the study uses techniques that bathe excised tissues in BPA, in a form not found in the body from BPA consumed in food, in a non-physiologically meaningful environment. BPA consumed in food or drink is rapidly and essentially completely metabolised before it enters the blood stream so cells within the body are not exposed to free BPA. ….These types of studies are the weakest form of epidemiological study and routinely throw up associations that cannot be confirmed as real by better designed and more robust approaches. That is, they are more likely to be irreproducible than real. Claimed associations between BPA metabolites in urine and developmental outcomes in humans are of this type.”
Professor Ian Rae: “The clinical results show that sensitive tissues exposed to very low concentrations of BPA experience adverse effects. It is not clear whether these tissues would ever be exposed in this way given normal ingestion patterns and known elimination pathways for BPA.
Prof Richard Sharpe: Interesting though the effects are from a mechanistic point of view, they have no relevance to human health because the concentration of bisphenol A used, exceeds human exposure by ~100,000 times (and this is probably a conservative estimate). …This study is reminiscent of many similar … but they always involve doses that are in a different ballpark to human exposure. When realistic doses are applied … no effects are found – although I hasten to add that most such studies never explore human-relevant doses.”