title: Phototoxicity testing in guinea-pigs.
abstract: The photoirritant potential of topically applied chemicals was studied using guinea-pigs. Solutions of test chemicals were applied to the skin, and after 30 min the animals were irradiated with near-ultraviolet radiation. Skin reactions were assessed subjectively between 3 and 72 hr after the start of treatment. Acridine and anthracene caused immediate photoirritation, whereas reaction to 8-methoxy-psoralen (8-MOP) was delayed; acridine was weakly active compared with the strong photoirritancy of anthracene and 8-MOP. Ethanol and a mixture of dimethylacetamide-acetone-ethanol (DAE) were satisfactory solvents, and a time interval of 15 to 30 min between application and irradiation was optimal. It is concluded that animal tests should not be recommended if ingredients have negligible absorption of sunlight. The safety hazard of ingredients absorbing near-ultraviolet and visible radiation may be assessed by laboratory animal procedures to satisfy governmental regulations. The use of guinea-pigs allows the study to act as a preliminary test for the selection of non-photoirritant concentrations for photoallergy testing and reduction of animal numbers. The risk to consumers of photoactive products may be properly assessed by human studies.
authors.affiliation: Environmental Safety Laboratory, Unilever Research, Colworth House, Sharnbrook, Bedford, UK.
authors.forename: W W
authors.initials: WW
authors.lastname: Lovell
authors.forename: D J
authors.initials: DJ
authors.lastname: Sanders
mesh_terms: D000166:Acridines / Q000008:administration & dosage / Q000633:toxicity*; D000287:Administration, Topical; D000818:Animals; D000873:Anthracenes / Q000008:administration & dosage / Q000633:toxicity*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006168:Guinea Pigs; D007700:Kinetics; D008730:Methoxsalen / Q000008:administration & dosage / Q000633:toxicity*; D010787:Photosensitivity Disorders / Q000139:chemically induced*; D012997:Solvents; D014466:Ultraviolet Rays
chemical_list: D000166:Acridines; D000873:Anthracenes; D012997:Solvents; C034020:anthracene; D008730:Methoxsalen