he current 50-μg/L maximum contaminant level (MCL) for arsenic in drinking water was first set by the US Public Health Service in 1942 and was adopted by the US Environmental Protection Agency (USEPA) in 1975.1 The standard was based primarily on toxic effects resulting from short-term or acute exposure to arsenic.2 Subsequent investigations have linked arsenic in drinking water with skin cance...

The US Army's need for a reliable and field-portable drinking water toxicity sensor was the catalyst for the development and evaluation of an electric cell-substrate impedance sensing (ECIS) device. Water testing technologies currently available to soldiers in the field are analyte-specific and have limited capabilities to detect broad-based water toxicity. The ECIS sensor described here uses r...

Nitrogenous disinfection by-products (N-DBPs) are far more cytotoxic and genotoxic than carbonaceous DBPs (Plewa & Wagner 2009). Among the N-DBPs, nitrosamines have been shown to be probable human carcinogens associated with 10–6 lifetime cancer risk at ng/L levels (USEPA 2002). An increasing number of water treatment plants (WTPs) in the United States have been using or considering chloraminat...

Discussions and applications of the policies and practices of the U.S. Environmental Protection Agency (USEPA) in ecological risk assessment will benefit from continued clarification of the concepts of assessment endpoints and of levels of biological organization. First, assessment endpoint entities and attributes can be defined at different levels of organization. Hence, an organism-level attr...

Toxicologically-based quantitative risk assessment is concerned with estimating human risks based upon experimental data linking an environmental agent to a known outcome (tumor incidence, acute toxicity, etc.). For dichotomous outcomes dose-response curves are modeled as complex functions of dose which often require specialized software to estimate. The SAS procedure NLMIXED readily allows for...