Selenium is an essential nutrient, and various selenium compounds have industrial and medical uses.
The possible carcinogenicity of selenium sulfide (a component in shampoos) was investigated by applying a suspension of this substance to the skin of ICR Swiss mice. Groups of 50 mice of each sex were treated by applying 0.5 mg or 1.0 mg selenium sulfide three times a week for 86 weeks to a clipped 2-x 3-cm dorsal surface. The selenium sulfide was suspended in 0.05 ml saline solution containing 0.5% carboxymethylcellulose.
Mean body weights of all dosed and control groups were comparable throughout the study. Amyloidosis, previously reported as a cause of death in Swiss mice, was a factor in the deaths of most treated and control mice after 1 year, andthe study was terminated after 88 weeks when the majority of animals in all dosed and control groups had died.
Under the conditions of this bioassay, dermal application of selenium sulfide did not produce a carcinogenic effect in ICR Swiss mice, but the study was limited by the relatively short lifespan of this strain of mouse.
Note: Selenium Sulfide was previously tested in F344 and B6C3F1 mice administered by gavage (See TR-194, reported 1980).