Risk assessment, remedial decisions and the challenge to protect public health: the perchlorate case study.

While scientists have a responsibility to defer judgment in the absence of conclusive data, public health and ecological protection require that government regulators make decisions based on available information. The risk assessment paradigm has evolved to help risk managers balance risks to public health with the cost of pollution control and remediation. Risk assessments are designed to be reasonably protective of public health, however the time and money required to develop and evaluate a robust scientific database can significantly delay regulatory action while exposures continue.

Estimates of exposures to perchlorate from consumption of human milk, dairy milk, and water, and comparison to current reference dose.

To develop an enforceable drinking water standard from a health-based reference dose, sources of exposure and relevant exposure factors across the U.S. population must be considered.

Suppression of superoxide production by chlorothalonil in striped bass (Morone saxatilus) macrophages: the role of cellular sulfhydryls and oxidative stress.

Chlorothalonil (TCIN) is the most commonly applied fungicide in the USA, with substantial use in the Chesapeake Bay area. Little is known about the sublethal toxicity of TCIN to fish, but since it is structurally similar to the immunotoxicant pentachlorophenol, the potential for immunomodulation exists. Previous studies have indicated that in vitro exposure of macrophages to TCIN modulates immunostimulated reactive oxygen species (H(2)O(2)/hypochlorous acid) and NADPH production in striped bass (Morone saxatilus).

The effects of chlorothalonil on oyster hemocyte activation: phagocytosis, reduced pyridine nucleotides, and reactive oxygen species production.

The production of reactive oxygen species (ROS) by a putative NADPH oxidase-like enzyme system is thought to contribute to antimicrobial activity in oyster hemocytes. NADPH oxidase in vertebrate phagocytes generates superoxide anion from molecular oxygen and NADPH, which is then converted to additional ROS, including H2O2 and HOCl. The fungicide chlorothalonil (TCIN) is a thiol-reactive compound that binds to protein sulfhydryl groups, which can result in enzyme inactivation.