title: Triggers for higher-order toxicity testing.
abstract: Strategies for selecting chemicals for definitive, higher-order toxicology tests are important because physical and personnel resources are limited and chemicals vary widely in the need for testing. The National Toxicology Program has developed strategies for selection of chemicals for definitive tests in several areas of toxicology. In addition to the number of people, the extent of human exposure, structure-activity considerations, and reports of observations in humans, specific triggers are sought from animal studies and short-term tests or in vitro screens which impact the chemical selection process and the design of definitive studies. Specific triggers in reproductive toxicology, for example, include observations in prechronic toxicology studies in rats and mice--weights and histopathologic examinations of reproductive organs, measurements of sperm production and function in males, and estrus cyclicity in females. Comparable tissue-specific triggers do not exist for developmental toxicity studies, and screening tests are not widely used for setting priorities for the conduct of definitive developmental toxicology studies.
authors.affiliation: Systemic Toxicology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC.
authors.forename: B A
authors.initials: BA
authors.lastname: Schwetz
authors.forename: R E
authors.initials: RE
authors.lastname: Morrissey
mesh_terms: D000818:Animals; D015197:Carcinogenicity Tests; D004353:Drug Evaluation, Preclinical; D005260:Female; D008297:Male; D051379:Mice; D009152:Mutagenicity Tests; D051381:Rats; D014116:Toxicology