Toxicity of Repeated Oral Intake of Organic Selenium, Inorganic Selenium, and Selenium Nanoparticles: A Review

The review paper discusses the toxicity of repeated oral intake of different forms of selenium, including organic, inorganic, and selenium nanoparticles. Selenium toxicity in humans can lead to symptoms such as a garlicky-smelling breath, hair loss, and nail changes. A human study showed increased mortality following daily ingestion of 300 µg of selenium per day for 5 years, equal to a lowest-observed-adverse-effect level (LOAEL) of approximately 4.3 µg/kg body weight per day. The corresponding no-observed-adverse-effect level (NOAEL) was approximately 2.9 µg selenium/kg body weight per day. Some studies reported an increased risk of type 2 diabetes after approximately 2.9 µg selenium/kg body weight per day, but other studies with similar doses found no increases in mortality or incidence of type 2 diabetes. In animal studies, selenium toxicity affected body weight with NOAELs ranging from 0.24–1.2 mg selenium/kg body weight per day. Other endpoints of selenium toxicity in animals include hepatotoxicity, gastrointestinal, cardiovascular, and reproductive toxicities with varying NOAELs. The dose descriptors describing selenium toxicity were as low as 2–3 µg selenium/kg body weight per day.