The US Environmental Protection Agency's (EPA) Office of Water requested that the National Research Council (NRC) review the arsenic toxicity database and evaluate the scientific validity of EPA's 1988 risk assessment for arsenic in drinking water. In 1975, EPA set the initial arsenic drinking water standard for community water supplies at 50 ug/L, (ppb) arsenic. EPA did not request nor did the committee endeavor to provide a formal risk assessment but provided an up-to-date summary appraisal of key elements in the risk assessment process, hazard identification and dose response that qualitatively if not quantitatively address the protective nature of the current MCL. This paper presents a summary of that report.