A US expert panel that reviews risks to human reproduction and growth posed by potential toxins has expressed some concern about the chemical bisphenol A which is present in plastic containers such as baby bottles. The panel recommended more research is needed to plug some of the gaps in the current scientific evidence.

The National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction (CERHR) convened an expert panel to evaluate bisphenol A. This was the second meeting of the panel of 12 independent scientists who met from 6th to 8th August in Alexandria, Virginia to assess evidence on the potential reproductive and developmental hazards of Bisphenol A.

Bisphenol A is a chemical ingredient of polycarbonate plastics, used in many consumer products from sunglasses and CDs to shatter resistant baby bottles and other food containers. It is also an ingredient of epoxy resins used to coat metal in food cans, bottle tops and water pipes.

In the human body, bisphenol A acts like estrogen, and when it was first discovered around 70 or so years ago it was considered as a synthetic estrogen but scientists took it no further because other more suitable compounds came along.

Humans come into contact with bisphenol A either by direct contact, or by exposure to food and drink that has been in contact with it, for instance through storage in a plastic container or can coated with it. Fetuses come into contact with it through the uterus as a result of the mother’s exposure.

The CERHR chose to evaluate bisphenol A because of its high production volume, widespread potential for human exposure, and some evidence of reproductive toxicity in animal studies. Another reason is the level of public concern; the chemical has been a topic of interest to various health and environmental groups.

The NTP expert panel reviewed the evidence about possible harm of exposure to bisphenol A across three groups: pregnant women and the unborn; infants and children; and adults. Their concern focused on human exposure, reproductive toxicity, and developmental toxicity.

Their conclusions covered four areas of human reproduction and development: neural and behavioural defects, prostate, accelerated puberty, and birth defects and malformations.

They reported their findings in terms of levels of concern: “negligible”, “minimal”, and “some concern”.

The expert panel expressed “some concern” that exposure to bisphenol A by the fetus and infants and children causes neural and behavioural defects.

They expressed “minimal concern” that exposure to bisphenol A affects the prostate of the unborn, or that it causes accelerations in puberty by being exposed to it in the uterus or in infancy and childhood.

The expert panel said it had “negligible concern” that fetal exposure to bisphenol A produced birth defects and malformations, or that it caused “adverse reproductive effects” in general population adults who are exposed to it in adulthood.

However, the panel said that in the case of adults who have above average exposure to bisphenol A, for instance because of their jobs, they would elevate their concern to “minimal”.

The NTP and the National Institute of Environmental Health Sciences established the NTP Center for the Evaluation of Risks to Human Reproduction (CERHR) in 1998 to be an environmental health resource for the public and to the regulatory and health agencies.

The CERHR was set up partly in response to health profession and public concern that exposure to chemicals in our environment may be causing or indirectly contributing to disorders in human reproduction and development.

According to the CERHR, between 5 and 10 per cent of couples trying to have children have problems getting pregnant, 35 to 50 per cent of pregnancies fail, and 3 to 5 per cent of newborns have significant birth defects. The cause and development of these problems is largely a mystery.

Click here for more information on the Bisphenol A – Second Expert Panel Meeting (NTP-CERHR page).

Written by: Catharine Paddock