Ames assays by McCoy and Rosenkranz in 1978 with silver sulfadiazine, on several strains of Salmonella typhimurium did not demonstrate any gene mutations. Bacillus subtilis subjected to silver chloride by Nishioka in 1975 showed no indications of mutagenicity. Beta-galactosidase and alkaline phosphatase activities in Escherichia coli did not change after treatment with silver nitrate (Olivier and Marzin 1987). These are all indications of no mutagenicity by silver.