Updated Problem Formulation and Protocol for the Inorganic Arsenic (iAs) IRIS Assessment
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In May 2019, the U.S. Environmental Protection Agency (EPA) released the updated problem formulation and protocol for the iAs assessment. The updated problem formulation includes the refined scope that specifies which health outcomes are prioritized for dose-response analyses and toxicity value derivation. The protocol includes the methods and approaches proposed for use in developing the assessment. Epidemiology studies will be the focus of the assessment, consistent with prior National Research Council (NRC) of the National Academy of Science (NAS) input. EPA considered strength of the epidemiological evidence for hazard by relying on conclusions from assessments conducted by other health agencies or by conducting new systematic reviews of the existing literature. Based on qualitative hazard analyses of the iAs literature, the following health outcomes were identified for potential dose¿response analyses based on sufficient human evidence: cancers of the bladder, lung, kidney, liver, and skin; and noncancer effects of iAs on the circulatory system (ischemic heart disease, hypertension, and stroke), reproductive system (including pregnancy and birth outcomes), developmental outcomes (including neurodevelopmental toxicity), endocrine system (including diabetes), immune system, respiratory system, and skin. The NRC released their review of these materials, supporting EPA’s refined scope and methods, in October 2019.