A new study claims that bisphenol A causes heritable changes in gene expression.
This study is classic low-dose junk science:
- An arbitrary dose is tested and claimed to be relevant to human exposure based on outdated research, namely the 2007 Vandenberg et al paper (ref. 24). In fact the dose tested, 2-4.6 ng/mL in blood are orders of magnitude higher than actual human exposure based on the latest research (Teeguarden et al., 2011).
- A small number of test animals are used in the control and test groups, to ensure high probability of variance between control and test groups. Only a single dose is tested and compared to controls; there are no historic (baseline) controls used to compare control values. A large number of potential variable are examined. Any difference between control and test is declared to be a biologically important result. Inconsistencies in patterns of test results are ignored.
Thus, the authors report:
- “Juveniles in the first generation exposed to BPA in utero displayed fewer social interaction as compared with control mice, whereas in later generations (F2 and F4), the effect of BPA was to increase these social interactions.” Note not only the opposite effects in first vs. second and fourth generation, but also that there were no difference in the third generation. I would call that a random pattern of comparisons if I ever saw one!
- The study also reports depressed levels of vasopressin and oxytocin (only in males) mRNA synthesis, without even bothering to try to explain the relevance of these effects (there isn’t any), especially in view of the fact that the behavior effects were claimed to occur in both males and females.
- Any differences between test and control animals are claimed to demonstrate the potential for adverse health effects in humans although no adverse effects were demonstrated in animals. Thus the paper claims that their study has “implications for complex neurological diseases and highlight the importance of considering gene-environment inactions in the etiology of complex disease.”
This is classic low dose hypothesis junk science.
The authors also suggest that BPA has transgenerational effects through 4 generations (“Because exposure to BPA changes social interactions at a dose within the reported human levels, it is possible that this compound has transgenerational actions on human behavior.”), which they further suggest must be caused by germline epigenetic effects. Absolutely no evidence for germline epigenetic effects is presented in the paper. For that matter, no epigenetic evidence of any kind, germline or otherwise, is provided in paper.
The media release is below.
BPA exposure effects may last for generations
New study shows gestational exposure to BPA leads to behavioral changes for 4 generations
Chevy Chase, MD—Exposure to low doses of Bisphenol A (BPA) during gestation had immediate and long-lasting, trans-generational effects on the brain and social behaviors in mice, according to a recent study accepted for publication in the journal Endocrinology, a publication of The Endocrine Society.
BPA is a man-made chemical present in a variety of products including food containers, receipt paper and dental sealants and is now widely detected in human urine and blood. Public health concerns have been fueled by findings that BPA exposure can influence brain development. In mice, prenatal exposure to BPA is associated with increased anxiety, aggression and cognitive impairments.
“We have demonstrated for the first time to our knowledge that BPA has trans-generational actions on social behavior and neural expression,” said Emilie Rissman, PhD, of the University of Virginia School of Medicine and lead author of the study. “Since exposure to BPA changes social interactions in mice at a dose within the reported human levels, it is possible that this compound has trans-generational actions on human behavior. If we banned BPA tomorrow, pulled all products with BPA in them, and cleaned up all landfills tomorrow it is possible, if the mice data generalize to humans, that we will still have effects of this compound for many generations.”
In this study, female mice received chow with or without BPA before mating and throughout gestation. Plasma levels of BPA in supplemented female mice were in a range similar to those measured in humans. Juveniles in the first generation exposed to BPA in utero displayed fewer social interactions as compared with control mice. The changes in genes were most dramatic in the first generation (the offspring of the mice that were exposed to BPA in utero), but some of these gene changes persisted into the fourth generation.
“BPA is a ubiquitous chemical, it is in the air, water, our food, and our bodies,” said Rissman. “It is a man-made chemical, and is not naturally occurring in any plant or animal. The fact that it can change gene expression in mice, and that these changes are heritable, is cause for us to be concerned about what this may mean for human health.”