The US Environmental Protection Agency’s (EPA’s) Integrated Risk Information System (IRIS) program published for public comment a draft protocol for reassessing the noncancer health effects of natural and depleted uranium via oral ingestion on February 14, 2024. The reassessment will examine whether newly available literature review or scientific analysis data could be considered for updating current hazards or whether there are additional health hazards related to uranium exposure.
The draft protocol presents the proposed methods for conducting the systematic review and radiological dose-response analysis. Results will be compiled in the Agency for Toxic Substances and Disease Registry’s Toxicology Profile. The purpose of the IRIS is to provide publicly available information on the toxicity of chemicals.
These assessments are not regulation and do not constitute EPA policy. Rather, they are used by EPA regional offices, states, local health agencies, Tribes, other federal agencies, and other external stakeholders as a scientific foundation for risk management decisions. The last natural and depleted uranium reassessment was issued in February 2013. Interested parties may submit comments on the draft protocol through March 15, 2024.
Natural and Depleted Uranium
The reassessment only covers the noncancer health effects of natural and depleted uranium. “Natural uranium” refers to uranium that is naturally found in nature, primarily in rocks and ores. As uranium-rich rocks and ores break down, the uranium can disperse into soils and waters.
Depleted uranium is the byproduct of the uranium enrichment process, and its high density makes it ideal for armor-piercing shells and as weights to balance aircraft. Depleted uranium often enters the environment because of its use in military conflicts. This reassessment does not include enriched uranium.
Oral Ingestion Pathway
The reassessment will only cover uranium health effects via oral exposure. The public’s primary exposure to uranium—albeit small—is through the ingestion of food and drinking water. Higher levels of uranium are seen in water from wells in uranium-rich rock. Uranium that is naturally present in soils can be absorbed into the roots of certain plants such as root crops. These routes of exposures may be amplified at Superfund sites with elevated uranium concentrations, such as at older uranium mines.
Scope
The primary health effects that this reassessment will focus on include urinary, hepatic, neurological, reproductive, and developmental concerns. Further, an increased evaluation of the susceptibility of uranium-induced musculoskeletal effects in the earlier life stages will be conducted due to the results of a preliminary literature survey. This evaluation will include the examination of potentially susceptible populations including women of childbearing age, pregnant women, infants, and children.