Fears Grow with Polycarbonate Chemical Bisphenol-A
Bisphenol-A (BPA), a chemical used to make polycarbonate and epoxy plastics, has come under fire recently for its status as an endocrine disruptor. The chemical is commonly used as an ingredient in consumer products, particularly reusable water bottles, baby bottles, plastic dishware, tooth fillings, and canned-food liners. It also appears in building products, including translucent panels, adhesives, and coatings. Although research about the chemical’s effects on the environment and human health is not conclusive, both the Canadian and U.S. governments have
expressed concerns over its safety.
In April 2008, Canada announced a proposal to list the chemical as toxic as well as to ban polycarbonate baby bottles containing BPA, set stringent targets for minimizing leaching of BPA into infant formula from can liners, and develop alternative food packaging. The move resulted from the government examining BPA as part of its Chemicals Management Plan, an ongoing assessment of several thousand chemicals feared to have negative environmental and human health impacts (see EBN Vol. 16, No. 1).
The Canadian report on bisphenol-A represents a thorough review of the scientific studies of the chemical and presents the government’s interpretation of the studies’ findings. It expresses concern that the chemical could interfere with reproductive functioning and neurological development in fetuses and infants. Although studies suggest that allowable thresholds for toxic exposure would be up to twice what current exposures are believed to be, the Canadian government chose to take a precautionary approach to the chemical.
Also in April, the National Toxicology Program (NTP) in the U.S. released a draft brief on BPA, following recommendations from the Center for Evaluation of Risks to Human Reproduction in 2007 (see EBN Vol. 16, No. 9). Reviewing much of the same research as the Canadians, NTP found that there was “some concern”¯ about BPA exposure for fetuses, infants, and children due to the developmental effects of the chemical. On the other hand, NTP found “negligible”¯ concern about birth defects caused by exposures in pregnant women as well as reproductive damage in adults; the brief also notes that there is “minimal”¯ concern about exposure rates in manufacturing workers.
Ninety percent of BPA exposure for the general public is through dietary sources, according to Michael Shelby, Ph.D., director of the Center for the Evaluation of Risks to Human Reproduction at NTP, since BPA leaches from can liners, polycarbonate bottles, and other containers into food. “At present,”¯ Shelby said, “it doesn’t look like there are other significant sources of exposure.”¯
The risk may be significant at the manufacturing phase, however. According to the NTP report, exposure levels in manufacturing workers are higher than those in the general population. BPA is water soluble, so a likely source for environmental release of the chemical is wastewater from polycarbonate and epoxy manufacturing plants. The Canadian report notes that BPA has been found in surface and groundwater in the U.S. and Canada, and suggests that it is likely being released into the air as well. Although not bioaccumulative—it does not work its way up the food chain—the chemical is toxic to aquatic organisms and is considered by the Canadian government to be “highly hazardous”¯ to the aquatic environment.