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Environmental science and policy professor Dale Hattis studies the level of cancer risk associated with exposure to a wide variety of chemical substances. He and student Jennifer Ericson worked to compile a related database bringing together research on age-related differences in cancer susceptibility. |
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Do you want fries with that?
Professor Dale Hattis's research
What do french fries and tuna fish have in common? They both contain chemicals that might jeopardize your health if consumed in high enough quantities. New research suggests that some fried foods contain a substance called acrylamide, a by-product of the frying process. As a result of toxic waste dumped into the ocean, tuna fish can be contaminated with mercury. But what if you only eat tuna occasionally? How great a risk of mercury poisoning would that really pose? How many acrylamide-containing french fries can you consume before you're at risk for cancer?
That's where risk assessment expert Dr. Dale Hattis comes in. Hattis, a geneticist by training, specializes in assessing the level of risk we assume when exposed to a wide variety of chemical substances. A former "Nader's Raider" and current advisor to the U.S. Environmental Protection Agency, Hattis has recently recommended that EPA-determined "safe" levels of chemical exposure be reevaluated. To find out more
- Read an online interview with Dr. Hattis and student researcher Jennifer Ericson
- Listen to a recent 30 minute radio interview with Hattis about the cancer-causing substance acrylamide found in many fried foods (courtesy of "The Public Eye" WICN radio). Note: you will need RealPlayer (free).
- Visit Dr. Hattis's web site
- Read below about Dr. Hattis's recommendation to the EPA.
Our skins, respiratory systems and digestive tracts are ports of entry for a wide variety of potentially dangerous chemicals. Toxic substances, in amounts ranging from insignificant to significant, are present in our home and work environments, the food we eat, the water we drink and the air we breathe. In an effort to insure that our exposure to these substances stays within the insignificant range, the Environmental Protection Agency sets acceptable levels of exposure to hundreds of potentially toxic substances. The EPA calls these acceptable levels "Reference Doses" (RfDs) or "Reference Concentrations" (RfCs). Many public and private agencies rely on these numbers when monitoring the levels of toxic substances in a wide variety of settings.
Over the last four years, Dr. Hattis, along with colleagues Robert Goble (also of Clark), and Sandra Baird (environmental consultant), created and tested what they think is a significant improvement on the present RfD/RfC approach. They concluded that the RfD/RfC approach currently used by the EPA does not provide a desirable level of protection. To reach this conclusion, they first compiled an extensive database summarizing research on differences in human sensitivity to a wide range of chemicals. Then, for 18 randomly selected environmental agents from EPA's central list of evaluated chemicals, they calculated new levels of acceptable exposure and compared these with the RfDs and RfCs for the same chemicals. The levels of acceptable exposure calculated by Hattis and his colleagues were based on
- research on variability in human sensitivity
- a more refined approach for estimating uncertainty than used in the EPA approach.
Dr. Hattis has proposed a reexamination of the "Reference Dose" and "Reference Concentration" approach, citing the following reasons:
- It's unclear how much protection the current RfDs and RfCs actually offer and the degree of risk that is incurred when those levels are exceeded.
- RfDs and RfCs are essentially "one size fits all" recommendations. In fact, the degree to which chemical exposure can be tolerated with no adverse effect varies from person to person. Body weight, age, genetic makeup, and pre-existing health problems are just some of the factors that influence a person's level of sensitivity. More data is now available about the effect of chemical exposure on population subgroups such as children and persons with preexisting health problems. The need for additional research in this regard would be made obvious with the adoption of new methods for determining risk.
- Sophisticated computers are now available that can create, compare, and analyze very large data sets, thereby making it easier to assimilate the many research studies available.
- Improved methods of uncertainty analysis are now available to study more accurately potential risk. When setting an acceptable level of chemical exposure, uncertainty analysis helps scientists take into account the reliability and relevance of different research findings. For example, standards based on an animals-only study would have a higher uncertainty rating than standards based on a study using human subjects. Current RfDs and RfCs incorporate only a crude estimate of uncertainty.
- RfDs and RfCs only address non-cancer health risks qualitatively. It would make more sense to have a consistent and comparable quantitative method for evaluating both cancer and non-cancer risks.
Perhaps future research will help us decide whether to risk that second helping of french fries or tuna salad.
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