Photocarcinogenesis and Consumer Product Testing: Technical Aspects

Abstract

Summary: Photocarcinogenesis is the production of tumors by sunlight. Since consumer products have been found to modify the course of cutaneous photocarcinogenesis in animal models, and since this modification is thought to be clinically relevant, we have developed and implemented procedures to evaluate a test article/substance as a potential modifier of photocarcinogenesis. Prior to beginning a photocarcinogenesis study, range-finding studies are conducted to determine certain characteristics of the test article/substance and its vehicle (e.g., primary irritancy, photosensitivity, and photoprotection). Additionally, the doses of test article/substance, the doses of sunlight exposure, and the most appropriate sequence for administering these two variables are determined from the range-finding studies and the intended use of the test article/substance. The test system is the Crl:SKH1 (hr/hr)BR, albino, hairless mouse. The source of “sunlight” is a 6.5 kW xenon arc lamp modified to emit radiation that simulates sunlight at the earth's surface. Methods for gathering and analyzing tumor data are discussed, and a theoretical study is used to facilitate the presentation. Three possible outcomes of this theoretical study are presented, and some unique features of the study are given. Any agent that can modify the carcinogenic effect of sunlight should be carefully considered with respect to its benefits and risks.

Key Words:

• Photocarcinogenesis
• Hairless mice
• Ultraviolet radiation
• Product testing
• Skin cancer
• Carcinogenesis