Nomination Summary for Thallium and thallium salts (N21607)
Nominated Substances: Metallic Thallium (Tl), Thallium & Salts, Thallium (I) acetate, Thallium (I) carbonate, Thallium chlorate, Thallium (I) chloride, Thallium (I) nitrate, Thallium (I) oxide, Thallium (III) oxide, Thallium selenide, Thallium (I) selenite, Thallium sulfate, Thallium (I) sulfate
Nomination Date: 06/03/2015
Nominator: U.S. EPA
Rationale: Uses, Exposures, and/or Effects: Uses: electronics/semiconductors, fireworks, former use in US as rodent poison. Exposures: water and dietary (hazardous waste sites) inhalation (fireworks emissions) and poisoning. Effects: clearly fatal to humans at high doses. As outlined in the IRIS Toxicological Review (2009), no adequate studies of chronic or subchronic mammalian toxicity. Regulatory or Public Health Need: Data are needed to better understand health effects. Thallium salts may cause a wide spectrum of adverse effects in humans, including alopecia, cardio-, neuro- and reproductive toxicity. Currently there are inadequate data for developing an oral reference dose and inhalation reference concentration. EPA Need/Timeline: In general, a subchronic rodent study is the minimum database that would support development of a reference dose for estimating human health risks from oral exposures. Timeline for EPA’s regulatory determinations is ongoing, because thallium is a frequent contaminant at hazardous waste sites. Key Questions/ Data Gaps: Data gaps include data to support hazard identification and dose response assessment of thallium. Toxicity endpoints other than lethality in a standard 90-day study with additional neuro- and repro-toxicity endpoints.
NTP Principles: not specified