Scientific efforts to prove or disprove harmful effects of bisphenol A, a chemical that is mainly used in combination with other chemicals to manufacture plastics and resins used as food contact materials, are gathering momentum. But have we reached the critical mass yet to draw the right conclusions. Let me explain.
Science is all about the exciting exploration of new findings or the more mundane task of other scientists trying to verify the new findings so that they can become established truths, or is it? To be honest, scientists can be a very conservative lot sticking to what they already believe they know. The more revolutionary the findings, the less is the likelihood that they will be accepted. Deviating from accepted thinking can be a dangerous thing and risk your career.
Here are three examples of how the scientific community initially refused to listen.
Environment influencing the genetic make-up
In a previous blog, the importance of epigenetics in understanding gene expression was covered. It was the heretic proposal that environmental factors could influence your genetic make-up and become hereditary. This was revolution and not easily accepted by the scientific community. During the 1940s and 1950s, Barbara McClintock discovered transposition and used it to show how genes are responsible for turning physical characteristics on or off. She developed theories to explain the repression or expression of genetic information from one generation of maize plants to the next. Encountering skepticism of her research and its implications, she stopped publishing her data in 1953.
Barbara McClintock was a dogged scientist believing that her findings were true despite ridicule from other scientists. It took her close to 40 years to prove the concept under constant threat to her position. It is now the hottest topic in biology and will have a major impact on future toxicological research. Barbara McClintock finally got full vindication by being awarded the Nobel Prize in Physiology or Medicine in 1983.
The low-dose theory
Equally important is the low-dose theory of chemical interaction with our bodily processes. According to conventional thinking the dose makes the poison and this is the basis for current chemical risk assessments. The higher the dose the more severe the effect is the accepted mantra, which makes sense to most of us. And here some scientists proposed that low doses of certain chemicals can have different and more pronounced effects than high doses, can that really be trusted?
Actually, there is an extensive body of research that purports to demonstrate such a phenomenon. Recently Edward Calabrese revived the theory through his research on peppermint plants giving rise to a scientific debate that has been gaining prominence over the last 20 years. Much research has focused on endocrine active substances or endocrine disruptors where the conventional relationship (more exposure equals higher risk) has been particularly challenged. Such substances have been shown to have fundamentally different (and harmful) effects on the body at low doses than at high doses. As seems to be the case for most scientific findings that challenge conventional thinking it took a long time for the scientific community to accept the low-dose theory and still there are some lingering doubts. In 2009, Calabrese was awarded the Marie Curie Prize for “outstanding achievements in research on the effects of low and very low doses of ionizing radiation on human health and biotopes”.
The contagious protein
Who has not heard about mad cow disease? It is the animal equivalent of Creutzfeldt-Jakobs Disease in humans, a debilitating brain disorder, the cause of which long was a mystery. And along came scientists proposing that the culprit was a misfolding protein that was contagious and thus could spread between individuals. Stanley Prusiner called it a prion, just a simple protein without any genetic material. The scientific community was astonished. This was just not possible.
It took years of experimentation to prove the theory. Now, of course, with the publicity of the mad cow disease many of us have heard about the prion. Whether prions are the agent which causes disease or merely a symptom caused by a different agent is still debated by a minority of researchers. However, the matter should be considered settled when Prusiner won the Nobel Prize in Physiology or Medicine in 1997 for his research into prions.
And what about new findings for bisphenol A?
The lesson from all of this? It is simply that it takes a lot of time and convincing arguments for scientists to change their mind. And now we have 21 scientists in the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids pondering about the fate of bisphenol A for the sixth time. Will the judgement be different on this occasion? One panel member already previously expressed a dissenting view, an unusual event in the short history of EFSA. But the peer pressure from the scientific community is high for status quo.
Yes, there are indications that bisphenol A might be an endocrine disruptor effective at very low doses. The effect might even be one explanation of many to the obesity epidemic. According to this theory exposure to bisphenol A might induce epigenetic changes turning on obesity genes. Changes that will be inherited by your off-spring. We will see in May 2013 when the new opinion is published if the new scientific findings are convincing enough. French scientists already believe they are and politicians in several countries have bowed for public pressure and as a precautionary measure banned bisphenol A from baby bottles. Endocrine disruptors are particularly dangerous during early life with rapid development easily influenced.
EFSA has been doing the groundwork by organising a scientific meeting to discuss low-dose effects. It met with French scientists in 2011 to discuss their conclusions. It further organised a Member State meeting in 2012 to air the views of European scientists. Finally, in co-operation with other European scientific advisory bodies, EFSA’s Scientific Committee is undertaking a review of all the current scientific information on endocrine active substances with the view of publishing an opinion in March 2013.
The pot is being stirred.
- The (Dual) Origin of Epigenetics (Harvard University, Cambridge, Massachusetts)
- Epigenetics in health and disease: A historical perspective (FT Press)
- Effects of Developmental Bisphenol A Exposure on Reproductive-Related Behaviors in California Mice (Peromyscus californicus): A Monogamous Animal Model (plosone.org)
- Upsetting the Balance: Endocrine Disrupters and Your Health (livingwellinkw.com)
- Study: Harmful effects of bisphenol A proven (rdmag.com)
- Pregnancy & Chemical Exposure (ellicecampbell.wordpress.com)
- BPA substitute could spell trouble: Experiments show bisphenol S also disrupts hormone activity (medicalxpress.com)
- Getting Endocrine Disruptors Out of New Chemicals (hefn.org)
- First Experimental Proof That Weak Concentrations Of Bisphenol A Produce A Negative Reaction On The Human Testicle (medicalnewstoday.com)
- Bisphenol A (BPA) Harms Human Fertility Harvard Study Concludes (activistpost.com)
- Why You Should Ditch Canned Foods (prn.fm)
- California plans to list bisphenol A as harmful chemical (mercurynews.com)