Environmental Protection Agency risk assessment approach

Anderson, E. L., and the Carcinogen Assessment Group of the US Environmental Protection Agency. (1983). Quantitative approaches in use to assess cancer risk. Risk Anal 3(4), 277-295. 

US-EPA. 1995. The use of the benchmark dose approach in health risk assessment. US Environmental Protection Agency (EPA), Office of Research and Development, Doc. EPA/630/R-94/007, Washington, DC. 

Uncertainty analysis is increasingly used in ecological risk assessment and was the subject of an earlier Pellston workshop (Warren-Hicks and Moore 1998). The US Environmental Protection Agency (USEPA) has developed general principles for the use of Monte Carlo methods (USEPA 1997), which provide one of several approaches to incorporating variability and uncertainty in risk assessment. 

Norton (1998) offers one approach from an ecological risk assessor s perspective. Various experts in statistics and risk assessment at the workshop preferred specific terms over others. The majority of the workshop participants were comfortable with distinguishing between uncertainty and variability in a manner that is consistent with US Environmental Protection Agency (USEPA) guidance. Other experts, particularly those associated with bounding analyses (see Chapter 6 of this book), preferred the word incertitude instead of uncertainty based on theoretical considerations associated with the bounding methods discussed in the chapter. 

EPA (1995a). U.S. Environmental Protection Agency. Use of the Benchmark Dose Approach in Health Risk Assessment, EPA/630/R-94/007 (National Technical Information Service, Springfield, Virginia). 

For classes of pesticides that cause their toxic effects through a common mechanism of toxicity, the non-occupational exposures to all members of the class have to be aggregated and used in a cumulative risk assessment. In 2003, the United States Environmental Protection Agency (USEPA) published a framework outlining how cumulative risk assessments should be conducted. There is no question that this approach has provided significant challenges to toxicologists, exposure assessors and risk assessors. Much of the developmental work on how to conduct... 

USEPA. Approaches for the application of physiologically based pharmacokinetic (PBPK) models and supporting data in risk assessment. Report number EPA/600/ R-05/043A. Washington, DC US Environmental Protection Agency, 2005. 

The objective of the work described here was to examine whether a similar approach can be used to assess chemical uptake into the skin in vivo from contaminated soil. It is now well recognized that human skin contact with contaminated soil can represent an important route of exposure to toxic compounds in occupational, environmental, and recreational settings. Data on the dermal uptake of chemicals from soil, especially in vivo, are limited, however, and those that do exist may underrepresent the true risk. This is because the amount of soil applied to skin in these experiments (1) greatly exceeds the mass of soil adhering to skin during a typical exposure (U.S. Environmental Protection Agency, 2001) and (2) may have provided multiple soil layers that do not contribute equally to dermal absorption (Bunge and Parks, 1998). 

Risk assessments are conducted under a far different set of guidelines. One of the first efforts to establish an upper limit for zinc intake was proposed by the Environmental Protection Agency (EPA) in the United States during their development of a reference dose for zinc. The reference dose, or RfD, is the level of substance intake that can be sustained for a lifetime without ill-effect. In setting an RfD the toxicologist tends to take a cautious approach. Copper and iron deficiency are known to be induced by high levels of zinc administration for example, a daily intake of 50 mg/day of supplemental zinc has been reported to produce modest inhibition of a red blood cell enzyme called superoxide dismutase. Whether or not this is a toxic effect remains a matter of conjecture to this day (8, 9). However, toxicologists, in the interest of public health, have tended to interpret this as a potentially adverse effect and 50 mg per day of supplemental zinc intake has become a point of reference for toxicity . 

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