%0 Journal Article
%T Toxicity of repeated oral intake of organic selenium, inorganic selenium, and selenium nanoparticles: A review.
%A Hadrup N
%A Ravn-Haren G
%J J Trace Elem Med Biol
%V 79
%N 0
%D 2023 Sep 2
%M 37285631
%F 3.995
%R 10.1016/j.jtemb.2023.127235
%X BACKGROUND: To protect from toxicity at supra-essential doses of selenium, it is important to determine dose levels at which adverse effects occur.
METHODS: We identified relevant literature on the repeated dosage of selenium and extracted dose descriptors on reported endpoints, except on genotoxicity/carcinogenicity.
RESULTS: Selenium forms with toxicological data were organic ones: selenomethionine, selenocystine/selenocysteine; and inorganic ones, including selenite (SeO32-), selenate (SeO42-), selenium sulphide (SeS2), selenide (Se2-) and selenium nanoparticles. Clinical signs of selenium toxicity in humans include a garlicky-smelling breath, hair loss, and nail changes. One human study showed increased mortality following daily ingestion of 300 µg Se per day for 5 years, equal to a lowest-observed-adverse-effect level (LOAEL) of ∼4.3 µg/kg bw/days. The corresponding no-observed-adverse-effect level (NOAEL) was ∼2.9 µg Se/kg bw/day. One study reported an increased risk of type 2 diabetes after ∼2.9 µg Se/kg bw/day, but other studies with similar doses found no increases in mortality or incidence of type 2 diabetes. NOAELs on affected body weight in animal studies were 0.24-1.2 mg Se/kg bw/day. Other endpoints of selenium toxicity in animals include hepatotoxicity with a NOAEL as low as 2 µg/kg bw/day in rats, as well as gastrointestinal, cardiovascular, and reproductive toxicities with NOAELs of 0.6 (gastrointestinal), 0.08, and 0.4 (cardiovascular) and ≥ 0.04 mg Se/kg bw/day (reproductive), respectively.
CONCLUSIONS: Dose descriptors describing selenium toxicity were as low as 2-3 µg Se/kg bw/day.