This case study is available in English, and is intended for advanced level primary care providers with the purpose to increase their knowledge of hazardous substances in the environment and to aid in the evaluation of potentially exposed patients. This case study covers at risk populations, exposure pathways, physiologic effects, clinical evaluation, treatment and management, standards and regulations, as well as workplace and environmental exposures related to arsenic toxicity. Upon completion of this case study the participant should be able to discuss the major exposure route for arsenic, describe two potential environmental and occupational sources of arsenic exposure, give two reasons why arsenic is a health hazard, describe three factors contributing to arsenic toxicity, identify evaluation and treatment protocols for persons exposed to arsenic, and list two sources of information on arsenic. The CDC designates this educational activity for a maximum of 1.5 hours in category 1 credit toward the American Medical Association (AMA) Physician's Recognition Award. 1.7 contact hours is provided by the CDC, which is accredited as a provider of continuing education in nursing by the American Nurses Credentialing Center's Commission on Accreditation. The CDC has also been approved as an Authorized Provider of continuing education and training programs by the International Association for Continuing Education and Training and awards 0.1 Continuing Education Units (CEUs).