In light of Ontario’s forthcoming Toxic Reduction Law, Jackie Campbell has taken a detailed look at one of the latest chemical health scares: how dangerous is bisphenol A (“BPA”)?
A recent, preliminary study has found high levels of urinary BPA in association with heart disease and diabetes in adults. This is the first good evidence that BPA may be toxic to adults, in addition to the threats to infants that Health Canada cited when proposing to name BPA a “toxic chemical”. Health Canada’s final screening assessment report on BPA under the Canadian Environmental Protection Act, 1999, is scheduled to be published on October 18, 2008, for public comment.
The JAMA study measured urinary levels of BPA in 1455 adults aged 18-74 years, in relation to 8 conditions: arthritis, cancer, heart disease, diabetes, liver disease, respiratory disease (eg asthma, bronchitis, emphysema), stroke, thyroid disease. Higher BPA concentrations were found only in association with heart disease, diabetes and liver damage. This is a preliminary study, and “association” is not proof of causation but it does give grounds for concern. Bottom line: The significance, if any, of high urinary levels of BPA is not yet known, but long-term studies are certainly needed. In the meantime, we are among the thousands who have switched from plastic to metal water bottles. And it’s another good reason to never have hot food or drink in contact with plastic.
What is our BPA exposure?
Most humans are exposed to BPA through food and water. Current rough estimates are:
· General population: 0.08 – 4.3 mcg/kg body weight per day.
· Infants 0-1 month of age: 0.50-4.3 mcg/kg body weight per day
· Infants 12-18 months: an average of 0.27 mcg/kg body weight per day
Typically, this BPA comes from:
· polycarbonate plastics (e.g., hard plastics, such as baby bottles, reusable water bottles; not soft, squeezable bottles)
· epoxy resins, used in protective linings of metal food and drink cans (including infant formula cans)
· hard plastic plates and cutlery
· some food storage containers.
Although an entirely artificial chemical, BPA is now found in Canadian surface waters, groundwater and municipal wastewater; concentrations as high as 40,000 mcg/kg dry weight have been reported in Canadian sewage sludge.
What pieces of the puzzle are missing?
Like most man-made chemicals, there is lots we don’t know about BPA even though we used 3,000,000,000 kg of it every year:
· The actual levels of BPA in consumer products
· How much of that leaches into our food and water
· The total amount of BPA we actually ingest from food, packaging etc. and who is most at risk
· The impact of chronic, low concentrations of BPA on human health, especially in children, given its known effect in animals on reproductive and nervous systems, and estrogen and thyroid hormone homeostasis
What is Canada doing about BPA?
BPA was identified as one of approximately 200 high-priority chemicals under Canada’s Chemicals Management Plan, because it may affect reproduction. The European Commission has already classified BPA as a category 3 reproductive toxicant. The Canadian government’s review of animal studies suggests that BPA exposure very early in life could have neurodevelopmental and behavioural effects.
The draft screening assessment prepared by the Environment and Health Ministers concludes that BPA may be entering the environment in a quantity or concentration or under conditions that may pose a danger to human life or health. Accordingly, the Ministers have recommended that BPA be classified as “toxic” to human health and the environment, and that it be added to the List of Toxic Substances in Schedule 1 of CEPA, as it meets toxicity criteria under ss. 64(a) and (c) of CEPA as set out under the Canadian Environmental Protection Act, 1999. The final decision should be made next year.
The US
The US FDA’s recently released “Draft assessment of BPA for use in food contact applications” concluded that there was an adequate margin of safety for BPA at current exposure levels. The JAMA study was released to coincide with a meeting of the US Food and Drug Administration’s Science Board Subcommittee, which is charged with peer-reviewing the FDA draft assessment of BPA. The final assessment should be published by late 2008. It will be interesting to see if the JAMA study has any impact on their conclusion.
REFERENCES:
JAMA articles (available for free download):
Lang IA et al. Association of urinary bisphenol A concentration with medical disorders and laboratory abnormalities in adults. JAMA 2008 Sept 17;300(11):1303-10
http://jama.ama-assn.org/cgi/reprint/300/11/1303
vom Saal FS & Myers JP. Bisphenol A and risk of metabolic disorders. JAMA 2008 Sept 17;300(11):1353-55
http://jama.ama-assn.org/cgi/reprint/300/11/1353
Additional Resources about BPA:
CANADA
Government of Canada. Chemical substances in batch 2 of the challenge. Last updated June 27, 2008. http://www.chemicalsubstanceschimiques.gc.ca/challenge-defi/batch-lot_2_e.html#ReleaseofDraft (includes timelines and links to
· Canada Gazette Notice (April 19, 2008)
· Draft Screening Assessment (fulltext)
· Risk Management Scope document
Health Canada. Health Canada responds to concerns raised about bisphenol A in canned food. May 29, 2008 (http://www.hc-sc.gc.ca/ahc-asc/media/nr-cp/_2008/2008_84-eng.php )
UNITED STATES
US Food and Drug Administration. Draft assessement of bisphenol-A for use in food contact applications. August 14, 2008:1-105 http://www.fda.gov/ohrms/dockets/AC/08/briefing/2008-0038b1_01_02_FDA%20BPA%20Draft%20Assessment.pdf
Briefing Information: US Food and Drug Administration Science Board Subcommittee, September 16, 2008. http://www.fda.gov/ohrms/dockets/AC/08/briefing/2008-0038b1_01_00_index.htm
US Department of Health and Human Services, National Toxicology Program, Center for the Evaluation of Risks to Human Reproduction. Bisphenol A evaluation. Provides links to several government and public documents. http://cerhr.niehs.nih.gov/evals/bisphenol/bisphenol.html