title: Light-induced genetic toxicity of thimerosal and benzalkonium chloride in commercial contact lens solutions.
abstract: Several commercial solutions used for daily care of contact lenses were tested for mutagenicity in 4 strains of Salmonella and for their ability to induce repairable DNA damage in the E. coli DNA polymerase A- assay. 5 of the 13 solutions tested were positive in the polymerase A- assay. These products demonstrated an increased level of genetic toxicity when the assay was conducted under conditions of illumination with visible light. Investigation of the genetic toxicity of some of their components, specifically the preservatives, indicated that thimerosal and benzalkonium chloride were capable of causing repairable DNA damage. Thimerosal was active only when the plates were incubated under conditions of illumination, and thus was light-induced. Benzalkonium chloride was active under conditions of dark incubation, and its genetic toxicity was enhanced when the plates were irradiated with visible light. These results were confirmed in a parallel experiment, in which cells were treated with the test agent and irradiated for a short period in liquid culture and viable cells then determined. None of the commercial products and none of the components tested, were mutagenic in the Salmonella assay.
mesh_terms: D001494:Baths; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D003261:Contact Lenses; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005035:Ethylmercury Compounds / Q000494:pharmacology*; D008027:Light; D009152:Mutagenicity Tests; D009153:Mutagens / Q000528:radiation effects; D013849:Thimerosal / Q000494:pharmacology*
chemical_list: D001548:Benzalkonium Compounds; D004269:DNA, Bacterial; D005035:Ethylmercury Compounds; D009153:Mutagens; D013849:Thimerosal