An Ignored Risk Factor in Toxicology: The Total Imprecision of Exposure Assessment (Report‪)‬

INTRODUCTION Exposure assessment is a key aspect of observational studies in human toxicology and epidemiology, where individual dosages are not part of the study design. In commonly used statistical analysis, the exposure variable is treated as an independent variable without error. Unfortunately, the frequently occurring non-differential errors in the exposure parameter tend to bias the dose-response relationship toward null [1]. Residence, occupation, and dietary questionnaire responses may be used as proxy variables that reflect an exposure. A better measure of individual exposure can be obtained from exposure biomarkers, i.e., contaminant concentrations in samples of human tissue or body fluids [2].