By Sarah Vogel
On Wednesday, May 14 the Senate Commerce, Science and Transportation Committee held a hearing on Plastics Additives in Consumer ProductsÂ to discuss the safety of two chemical compounds, bisphenol A (BPA) and phthalates, in consideration of new legislation and calls for regulatory reform. Both of these chemicals are used in plastics production and have long been known to be endocrine disruptors.Â In response to mounting evidence of the harmful health effects of BPA at very low doses of exposure, some manufacturers, the Canadian government, the State of California, and now members of Congress are taking action to restrict the use of this chemical.Â But the FDAâs position remains unchanged. The agency persists in considering BPA as a safe indirect food additive, despite the conclusion by the National Toxicology Program that there is some concern about neurological and reproductive effects of low doses of BPA in fetuses, infants and children.
In stark contrast to the position of the regulatory agency, members of Congress have taken the lead in pushing for greater protective health measures for children.
Senators Schumer (NY), Kerry (MA), Clinton (NY), Feinstein (CA), Durbin (IL) and Menendez (NJ) recently introduced the BPA-Free Kids Act of 2008 (S.2928 ), which would ban bisphenol A from all childrenâs products and also mandate the CDC to study the effects of exposure in ALL age groups, including pregnant women.Â Erring on the side of caution, Schumer emphatically declared to the Committee that Congress must act, âright here, right now. We cannot wait any longer.â
But the FDA chooses to wait.Â The agency declares that scientific uncertainty constitutes a justifiable reason to maintain the decades-old safety standard for BPA. Just what interests do the FDA seek to protect: the long-term health of people or the economic growth of the plastics industry? Senator Kerry asked Dr. Alderson of the FDA this very question.Â Doesnât the FDAâs exclusive reliance on industry data to set safety standards meant to protect the publicâs health bother him, Kerry asked.Â Alderson had no answer for the Senator. But in his written testimony Dr. Alderson parroted the plastics and chemical industriesâ argument for the safety of BPA.Â He remarked that the recent draft report of the National Toxicology Program (NTP) that raised some concern about the reproductive effects of low doses of BPA was based on new data and âdifficult-to-interpretâ findings.Â What is so difficult about research by Retha Newbold of the National Institutes of Environmental Health Sciences (NIEHS) that demonstrates low doses of BPA given early in development result in polycystic ovarian disease, or Ana Soto of Tufts Universityâs research that found an increase in mammary gland tumors in mice exposed during pregnancy to bisphenol A?Â
Whatâs âdifficultâ is that these endpoints donât fit the traditional toxicological model.Â The data from these studies may seem âdifficultâ because they incorporate elements of time, recognizing that the timing of exposure is inextricably tied to the endpoint.Â Even the slightest change in the timing of exposure may result in a different development outcome as the animal matures and develops.Â Because it draws careful attention to the dynamic of timing and the environmental relevancy of dose, this body of research on bisphenol A improves our understanding of real world human exposures and disease experience.Â The findings may also seem âdifficult to interpretâ because the relationship between the dose and the effect does not follow a monotonic dose-response curve (effects increase with dose), the preferable model used in risk assessment.
Why does the FDA presume that the effects of low dose exposure to BPA should be discrete or simple or follow a monotonic dose-response? Human disease and development are complex and dynamic.Â By insisting on the sufficiency of two industry funded multigenerational studies to support the FDAâs determination that bisphenol A as a food additive is safe, the agency sweeps aside hundreds of independent studies.Â Even further, the FDA ignores the rapid development in scientific research on endocrine disruptors that is grappling with the complexity of disease development and chemical exposure.Â The FDAâs safety standard assumes that the high doses used in these studies can be used to predict the health effects of the low levels found in humans.Â After all, shouldnât higher dose studies reveal these low dose effects?
Industry officials and Dr. Alderson would say âyes.â It would definitely make it easier for developing a risk assessment for bisphenol A.Â Yet, the evidence suggests otherwise.Â Data from dozens of independent low-dose studies are not simply anomalies with no theoretical support.Â There is a long history of theoretical development in the understanding of hormone receptor activity, epigenetics and fetal origins of disease that makes low dose data scientifically credible.Â John Peterson Myers, CEO of Environmental Health Sciences, in his oral and written testimony before the Senate Committee explained some of scientific theory supporting low dose research.Â Chemicals like BPA and phthalates act like hormones, and hormones, whether synthetic or natural, have long been known to function in complex feedback systems. As a result, as Myers argued, high dose studies can miss important adverse low dose effects, particularly when exposure occurs early in development.Â For this reason, regulatory toxicology used in the setting of safety standards has failed to protect the publicâs health.
The political stakes involved in this complex scientific debate must not be overlooked.Â For decades chemical safety has been based on the assumption that some exposure to chemicals is necessary and some risk inevitable.Â To balance this economic necessity, the assumption followed that at some low level a chemical could be safeârisk in this equation was determined by regulatory toxicology and benefit by industry.Â But science has changed and evolved.
Senator Pryor (AR), Chairman of the Committee, spoke to these broader concerns when he opened the hearingsâhe called attention to the larger implications this debate might have for regulatory reform and the future of chemical production.Â Members of this Senate Committee appear to understand that this debate about the safety of BPA and phthalates has far broader implications than the future of these two compounds.Â At stake is the means by which society determines chemical risks and benefits.Â Senator Kerry struck at the heart of the problem when he emphatically called the chemical regulatory system and agencies deficient, and urged reform of the Toxic Substances Control Act.Â
There are two sides to determining chemical safety â risk and benefit.Â For too long representatives of the petrochemical industry have had a dominant voice in defining both.Â If we want to begin to move towards a healthier and more sustainable world, the risks of chemicals must be based on cutting edge, independent scientific research â and the benefits of chemical production and use must not be determined solely by industry, loosely disguised as âconsumer choice.â Instead, future chemical production and use must be guided by independent research that is leading the way towards a greater understanding the complex relationship among genes, synthetic chemicals and disease development.Â
Sarah Vogel will receive her PhD fromÂ Columbia University in the Department of Sociomedical Sciencesâ Center for the History and Ethics of Public Health and Medicine in June. She holds masterâs degrees in public health and environmental management from Yale University. Her dissertation, âPolitics of Plastic: the economic, political and scientific history of bisphenol A,â was successfully defended in May 2008. She authored the case study âBattles Over Bisphenol Aâ at DefendingScience.org.