US EPA

EPA has finalized the Integrated Risk Information System (IRIS) Assessment of Ammonia (Noncancer Inhalation). This assessment addresses the potential noncancer human health effects from long-term inhalation exposure to ammonia. Now final, this assessment will update the current toxicological information on ammonia posted in 1991. EPA’s program and regional offices may use this assessment to inform decisions to protect human health.

Ammonia occurs naturally in air, soil, and water. Ammonia is also produced by humans and other animals as part of normal biological processes. Ammonia is used as an agricultural fertilizer and in many cleaning products. Exposure to ammonia occurs primarily through breathing air containing ammonia gas, and may also occur via diet, drinking water, or direct skin contact. Concentrations of ammonia measured in ambient outdoor air range from 0.28‒15 μg/m³ and in indoor air from 0.09–166 μg/m³.

Health effects of inhaled ammonia observed at levels exceeding naturally-occurring concentrations are generally limited to the respiratory tract, the site of direct contact with ammonia. Short-term inhalation exposure to high levels of ammonia in humans can cause irritation and serious burns in the mouth, lungs, and eyes. Chronic exposure to airborne ammonia can increase the risk of respiratory irritation, cough, wheezing, tightness in the chest, and reduction in the normal function of the lung in humans. Studies in experimental animals similarly indicate that breathing ammonia at sufficiently high concentrations can result in effects on the respiratory system. Animal studies also suggest that exposure to high levels of ammonia in air may adversely affect other organs, such as the liver, kidney, and spleen.

EPA completed the Integrated Risk Information System (IRIS) health assessment for ammonia. IRIS is an EPA database containing Agency scientific positions on potential adverse human health effects that may result from chronic (or lifetime) exposure to chemicals in the environment. IRIS contains chemical-specific summaries of qualitative and quantitative health information in support of two steps of the risk assessment paradigm, i.e., hazard identification and dose-response evaluation. IRIS assessments are used in combination with specific situational exposure assessment information to evaluate potential public health risk associated with environmental contaminants.

U.S. EPA. IRIS Toxicological Review of Ammonia Noncancer Inhalation (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-16/163F, 2016.