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Should Bisphenol A be banned?
Should Bisphenol A be banned?
This week Breast Cancer UK
called for a Government ban on use of Bisphenol A in the
production of baby bottles.
Breast Cancer UK says
there is "clear and compelling scientific evidence" that
links BPA, an organic chemical compound used for the last 50
years in the production of a wide range of plastic products,
with "increased risk of breast cancer and other chronic
conditions".
The Science Media Centres in the UK and New Zealand asked scientists for their views on the safety of BPA.
See below for a Science Media Centre UK fact sheet on Bisphenol A.
Ian Shaw, Professor of Toxicology in the Department of Chemistry at the University of Canterbury comments:
"I don't think we should ban BPA, but I think we should control its use much more carefully. BPA is the chemical used to manufacture polycarbonate plastics, is a component of lacquers used to line food cans, and is used in some dental fillings - the problem is that it mimics the female hormone. Small doses over a long time can initiate female hormone responses.
"In males this might result in undescended testes or other sex organ deformities, but in females it is possible that some breast cancers might be stimulated. A specific type of breast cancer (estrogen receptor positive breast cancer) grows when the female hormone, estrogen, binds to a specific receptor in the cell; when the receptor is occupied the cancer cell divides and the cancer grows. An estrogen mimic such as BPA can bind to the receptor and stimulate the breast cancer cell to divide. Controlling its use while allowing it to be used for the benefit of society (e.g. in some medical devices) will reduce exposure and so reduce the risk."
From the SMC UK:
Professor Richard Sharpe, Medical Research Council Human Reproductive Sciences Unit based at University of Edinburgh, said:
"There is no direct evidence that links bisphenol A exposure in women, or in animal studies, to the development of breast cancer. Bisphenol A is an extremely weak oestrogen and is therefore unlikely to contribute significantly to a woman's lifetime oestrogen exposure (and thus to her risk of breast cancer). Much of the data on low dose effects of bisphenol A have proved to be unrepeatable in more detailed, follow-up studies that have used the route of exposure (oral) relevant to humans, meaning that they do not satisfy one of the fundamental criteria for good science. In my opinion, any call for action on bisphenol A first requires direct evidence that, at human oral exposure levels, it can be shown capable of inducing breast cancer in animal models."
Dr Warren Foster, Director and Professor of CIHR/Ontario Women's Health Council and Director of the Reproductive Biology Division in the Department of Obstetrics & Gynecology at McMaster University, Ontario, said:
"BPA is a very weak estrogen relative to the body's
own estrogen called estradiol. Indeed some standard tests
for estrogenicity fail to detect any estrogenic action of
this chemical. It is estimated to be approximately
1/10,000th the potency of estradiol or in simple terms if
one person makes 10,000 dollars/year someone else making
1/10,000th as much would receive 10.00
dollars/year.
"BPA, although ubiquitous in our
environment, is poorly absorbed by the body. It is estimated
that between 95 and 99% of BPA is metabolized by the body or
the gut microflora and excreted from the body in either the
feces or urine.
"The concentration of BPA measured
in tissues is usually in the ppt (parts per trillion) range
which is roughly equivalent to being able to measure one
specific second in 31.7 thousand years. Our ability to
measure BPA in tissues represents great improvements in
analytical chemistry rather than evidence of increased
exposure to chemicals or increased risk.
"Breast
cancer is a complex disease with many different types of
cancer. While estrogens are known to be cancer promoters
there is no evidence that BPA is a cancer inducer and there
is sparse evidence that BPA can act as a cancer promoter
especially at the concentrations present in
humans.
"People are exposed daily to a vast number
of chemicals with mixed actions including estrogenic,
anti-estrogenic and anti-androgenic as well as no known
hormone like activity. At present there is no credible
evidence to suggest that contemporary exposures are linked
with increased risk of breast cancer.
"The greatest
potential for environmental chemicals to impact on disease
is in the area of disease progression. In this regard there
is weak evidence that BPA could enhance breast cancer
aggressiveness and promote progression of this
disease.
"Relative to other chemicals to which
people are exposed such as the phthalates, BPA presents
minimal health
concern."
ends
Science Media Centre NZ
Our aim is to promote accurate, evidence-based reporting on science and technology by helping the media work more closely with the scientific community.
The Science Media Centre is New Zealand's only trusted, independent source of information for the media on all issues related to science. Thousands of news stories providing context from and quoting New Zealand researchers have been published as a direct result of our work.
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