15 Environmental biometry: Assessing impacts of environmental stimuli via animal and microbial laboratory studies

Environmental bioimetry is the study and application of statistical methods in environmental studies on biological systems. In the areas of toxicology and environmental health, the damaging effects of environmental chemicals or other stimuli are often studied in animal and microbial systems. Data from such experiments are analyzed via various statistical approaches, each depending on the nature of the endpoint and aspects of the particular assay under study. Among major endpoints of interest, those of carcinogenicity, mutagenicity, and teratogenicity often garner greatest attention, and analyses for these three endpoints are discussed in this chapter. Statistical issues of interest include dose-response estimation and testing, including settings where variance heterogeneity and overdispersion are present. Similarities among the various endpoints and their biometric analyses are illustrated with data on toxicological response to 1,3-butadiene, a gaseous toxin found in cigarette smoke and automobile exhaust.