The maligned bisphenol A
August 29, 2012 1 Comment
Bisphenol A (BPA) is an industrial chemical used since the 1960’s as an ingredient in making a clear plastic known as polycarbonate. Polycarbonate is used to make a variety of common products including baby and water bottles, sports equipment, medical and dental devices, dental fillings and sealants, CDs and DVDs, household electronics, and eyeglass lenses. BPA is also found in epoxy resins, which act as a protective lining on the inside of metal-based food and beverage cans. It can leach into food, and a study of over 2,000 people found that more than 90 percent of them had BPA in their urine. Traces have also been found in breast milk, the blood of pregnant women and umbilical cord blood.
BPA is permitted for use in food contact materials in the European Union (EU) and in most other countries. In the past, the European’s Scientific Committee on Food, the European Chemicals Bureau, the European Food Safety Authority, and the US Food and Drug Administration all concluded that current levels of BPA present no risk to the general population. However, recently it was found to exert detectable hormone-like properties, raising concerns about its presence in consumer products and foods contained in such products. Starting in 2008, several governments questioned its safety, prompting some retailers to voluntarily withdraw polycarbonate products. Canada was the first country to ban the use of BPA in baby bottles from 2010 followed by the European Commission in January 2011. In 2012, also the United States banned the use of BPA in baby bottles including in infant feeding cups.
Bisphenol A toxicity
There is a great diversity of opinion about the health effects of BPA. Overall, empirical evidence in support of negative health effects of BPA varies significantly across studies. Standardised toxicity tests used globally for regulatory decision-making long supported the safety of current low levels of human exposure to BPA. However, results of recent studies using novel approaches and different endpoints found detrimental effects in laboratory animals at very low doses similar to estimated human exposure.
Several new studies evaluated developmental or behavioural effects that are not typically assessed in standardised tests. For example, perinatal exposure to BPA in rodents modified sex differences in the brain. In mice, prenatal exposure to BPA was associated with increased anxiety, aggression and cognitive impairment. In the offspring of BPA-exposed monkeys, males displayed less social behaviours and were more exploratory. In humans, BPA exposure during gestation has been associated with hyperactivity and aggression in young children and with anxiety and depression in older children. Together, these reports and many others demonstrate that BPA exposure during gestation affects several types of behaviours in a number of species.
It is clear that bisphenol A is a weak endocrine disruptor, which can mimic oestrogen and may lead to negative health effects. Early developmental stages seem to be the period of greatest sensitivity to its effects. Regulatory bodies have determined safety levels for humans, but those safety levels are being questioned or are under review as a result of the new findings. Experts in the field of endocrine disruptors have stated that the entire population may suffer adverse health effects from current BPA levels. In 2009, the Endocrine Society released a statement citing the adverse effects of endocrine-disrupting chemicals, and the controversy surrounding BPA.
In 2010, the WHO organised an expert meeting to review toxicological and health aspects of BPA supported by Health Canada, the European Food Safety Authority, the U.S. National Institute of Environmental Health Sciences and the US Food and Drug Administration. Although the meeting concluded that doses much higher than estimated human exposure were necessary for most toxicological effects, it did agree that for some emerging effects, like sex-specific neurodevelopment, anxiety, preneoplastic changes in mammary glands and prostate in rats, and impaired sperm parameters, a few studies showed associations at levels close to estimated human exposure. Because of the considerable uncertainty of the validity and relevance of these observations it was recommended that further research should be undertaken to reduce the uncertainty.
Re-evaluation of human risks
EFSA completed a full risk assessment of BPA in 2006 and set a limit of 0.05 mg/kg body weight per day that could be ingested daily over a lifetime without appreciable risk (Tolerable Daily Intake – TDI). It evaluated intakes of BPA through food and drink, for adults, infants and children and found that they were all well below the TDI.
EFSA has updated its scientific advice on BPA several times since 2006, most recently updating its risk assessment in 2011, reaching similar conclusions.
In February 2012, following further consideration of new scientific studies, EFSA decided to undertake a full re-evaluation of the human risks associated with exposure to BPA through the diet, also taking into consideration the contribution of non-dietary sources to the overall exposure to BPA. The new opinion will review all the available data and scientific studies on dietary exposure published since EFSA’s 2006 Opinion. The Panel will further evaluate uncertainties about the possible relevance to human health of some BPA-related effects observed in rodents at low dose levels.
FDA is also continuing to consider the low dose toxicity studies of BPA as well as other recent peer-reviewed studies related to BPA. At this stage, FDA has stated its current perspective on BPA, its support for further studies, its establishment of a public docket for its assessment of BPA use in food contact applications. FDA has issued interim public health recommendations, including its view of the appropriate regulatory framework for BPA use in food contact applications. It is expressing the wish to pursue the issue in collaboration with international partners.
- Update on bisphenol A (EFSA)
- Comments on the use of bisphenol A (FDA)
- Views on bisphenol A (Health Canada)
- Joint FAO/WHO expert meeting to review toxicological and health aspects of bisphenol A (WHO)
- Scientific publication on the gestational effects of BPA (Endocrinology)
- Big chem, big harm (New York Times)
- Keeping it in the family: BPA might last in our bodies for generations (grist.org)
- BPA: More Unanswered Questions? (foodworksblog.wordpress.com)
- Think Twice Next Time About Touching a Receipt with Your Bare Hands — Your Unborn Child May Thank You for It (alternet.org)
- BPA is safe in food contact materials (bangordailynews.com)
- Negative effects of plastic’s additive blocked by nutrient supplements ( folic acid, genistein ) – bisphenol A (BPA) (engineeringevil.com)
- Bisphenol A exposure linked to brain tumor diagnosis. (elephantjournal.com)
- What is BPA and why is it bad? (evolveism.com)