US EPA

In November 2023, EPA released the Protocol for the Nitrate and Nitrite IRIS Assessment (Oral) (Preliminary Assessment Materials) for a 30-day public review and comment period. As part of developing a draft IRIS assessment, EPA presents a protocol that describes the methodology for how the assessment will be conducted, including systematic review and dose-response. These could include strategies for literature searches, criteria for study inclusion or exclusion, considerations for evaluating study methods, information management for extracting data, approaches for synthesis within and across lines of evidence, and methods for derivation of toxicity values.

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 document presents a draft protocol for nitrate and nitrite that will be the subject of an SAB/Chemical Assessment Advisory Committee meeting in early 2024 and that will define the development of the draft IRIS assessment for nitrate and nitrite.

The IRIS Program will use the protocol to develop the draft assessment.

U.S. EPA. Protocol for the Nitrate and Nitrite IRIS Assessment (Oral) (Preliminary Assessment Materials). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-23/337, 2023.