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Background: The National Research Council (NRC) Committee on Improving Risk Analysis Approaches Used by the U.S. EPA (Environmental Protection Agency) recommended that low-dose risks be estimated in some situations using human variability distributions (HVDs). HVD modeling estimates log-normal distributions from data on pharmacokinetic and pharmacodynamic variables that affect individual sensitivities to the toxic response. These distributions are combined into an overall log-normal distribution for the threshold dose (dose below which there is no contribution to a toxic response) by assuming the variables act independently and multiplicatively. This distribution is centered at a point-of-departure dose that is usually estimated from animal data. The resulting log-normal distribution is used to quantify low-dose risk. Objective: We examined the implications of various assumptions in HVD modeling for estimating low-dose risk. Methods: The assumptions and data used in HVD modeling were subjected to rigorous scrutiny. Results: We found that the assumption that the variables affecting human sensitivity vary log normally is not scientifically defensible. Other distributions that are equally consistent with the data provide very different estimates of low-dose risk. HVD modeling can also involve an assumption that a threshold dose defined by dichotomizing a continuous apical response has a log-normal distribution. This assumption is shown to be incompatible (except under highly specialized conditions) with assuming that the continuous apical response itself is log normal. However, the two assumptions can lead to very different estimates of low-dose risk. The assumption in HVD modeling that the threshold dose can be expressed as a function of a product of independent variables lacks phenomenological support. We provide an example that shows that this assumption is generally invalid. Conclusion: In view of these problems, we recommend caution in the use of HVD modeling as a general approach to estimating low-dose risks from human exposures to toxic chemicals. [ABSTRACT FROM AUTHOR]

The Supreme Court's split decision in Rapanos v. United States left the lower courts with the question of whether to apply the plurality's restrictive test for determining which waters are protected under the Clean Water Act (CWA), or whether to use Justice Kennedy's more flexible, policy-based test. For those courts intending to follow Kennedy's concurrence, the parameters of his "significant nexus" test were far from explicit. In Baykeeper v. Cargill Salt Division the Ninth Circuit relinquished its first opportunity to apply the significant nexus test expansively in order to keep the CWA potent as a tool for environmental protection. The best remaining approach for litigants seeking to establish CWA coverage of non-navigable-in-fact waters that are not wetlands is to proceed under the theory that such waters are tributaries with a significant nexus to navigable waterways, pressing this language into service in the broadest array of hydrological scenarios possible. [ABSTRACT FROM AUTHOR]

During the 1990s, American Indian Nations assumed regulatory primacy over certain portions of federal environmental laws in the United States. For tribes that have not developed their own standards, the U.S. Environmental Protection Agency (EPA) issued policy statements aimed at incorporating tribal health and natural resources. While many communities of color have to fight to get heard in state and federal permitting processes, the U.S. EPA has made it an explicit mission to always include Indian Nations. Thus, "getting to the decision-making table" - a key goal of environmental justice groups - is presumably serving the interests of tribes seeking environmental justice. However, being involved in regulatory processes, as tribes are, may not be enough for Indian Nations or other communities of color. It is to this end that I write this article - should "getting to the table" be the ultimate goal for environmental justice groups, and how should this table be structured? [ABSTRACT FROM AUTHOR]

This article focuses on the U.S. Environmental Defense Fund, an action-oriented environmental organization created in 1967. The organization has four major programs that focus on energy, land and water, toxics, and wildlife, although individual projects may bridge these areas. The programs are supported by income arising in roughly equal parts from national membership fees, grants from foundations, and gifts from individual donors. The Environmental Defense Fund developed out of the 1967 effort by several scientists on Long Island to reduce the indiscriminant spraying of DDT, an activity that was rapidly destroying populations of ospreys and other birds high on the food chain. By 1979, the Environmental Defense Fund had a staff well versed in the paths by which toxics move through the environment and skilled in legal tools an risk-benefit arguments needed to reduce the dispersal of toxic substances and to force the cleanup of earlier depositions. The toxics program at the Environmental Defense Fund covers a wide range of topics, including lead in gasoline, chlorine in sewage treatment plant discharges, mercury and uranium in streams, and carbon monoxide and sulfur dioxide in the air.

The author reflects on the role of the U.S. Environmental Protection Agency in supporting, stimulating, and encouraging the higher education and training of professional environmental pollution control practitioners. The author has stressed that the role of the agency was a broader and more complex question, involving a variety of federal agencies, policies, and programs, deserving of very serious consideration by those primarily responsible and knowledgeable about it.

The article discusses the fundamental change needed for chemical toxicity testing in the U.S. The National Academies' National Research Council urges in its "Toxicity Testing in the Twenty-First Century: A Vision and a Strategy," that a rapid shift is needed to shift away from the entrenched reliance on animal testing, as requested by the U.S. Environmental Protection Agency (EPA). The committee says this information, combined with multidisciplinary research on human populations and the fate of chemicals in the environment, could lead to better models for predicting chemical effects on critical pathways in the human body.