US EPA

An IRIS Assessment Plan (IAP) communicates to the public the plan for assessing each individual chemical and includes summary information on the IRIS Program’s scoping and initial problem formulation; objectives and specific aims for the assessment; the PECO (Populations, Exposures, Comparators, and Outcomes) criteria that outlines the evidence considered most pertinent to the assessment; and identification of key areas of scientific complexity. The PECO provides the framework for developing literature search strategies and inclusion/exclusion criteria, particularly with respect to evidence stream (i.e., human, animal, mechanistic), exposure measures and outcome measures.

Nitrate (NO3−) and nitrite (NO2−), naturally occurring anions in the environment, play an essential role in Earth’s nitrogen cycle. Since 1950, human sources of nitrogen have increased substantially, creating a global surplus of nitrate/nitrite that supersedes natural sources by about 30%. Nitrate salts are mainly used as nitrogen fertilizers and in industrial explosives, fireworks, and glass making, whereas nitrites are largely used as preservatives for meat and fish curing and as color fixatives.

This outcome from the release of this document of the draft assessment plan for nitrate and nitrite that will be the subject of an SAB/Chemical Assessment Advisory Committee meeting that will was held September 2017 in order to define the scope and approach for the development of the IRIS assessment for nitrate and nitrite.

U.S. EPA. IRIS Assessment Plan for Nitrate and Nitrite (Scoping and Problem Formulation Materials, 2017). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-17/331, 2017.