Exposure assessment of laboratory workers to hazardous waste from mice treated with tamoxifen and bromodeoxyuridine

Animal research frequently involves the use of hazardous chemicals such as carcinogens, reproductive toxins or other highly toxic substances. Animal facility workers and researchers may be exposed to these chemicals when treating animals, or handling cages or bedding of animals excreting these chemicals or their toxic intermediates. Handling of hazardous chemicals in animal facilities follows the chemical hygiene plan conventionalized for research laboratories but not animal facilities. Exposure to these chemicals in animal excretions (urine and feces) has not been fully evaluated. The goal of this case study was to understand how much and for how long hazardous select chemicals are excreted by male and female laboratory mice. We examined the metabolic fate of two hazardous chemicals commonly used in animal research: tamoxifen and bromodeoxyuridine (BrdU). In this study, excretion rates of tamoxifen and its two bioactive metabolites (hydroxytamoxifen and endoxifen) showed a dose-sex interaction; but, excreted concentrations reached very low to undetectable levels by 72 hour post treatment no matter the dose or sex of the animal. BrdU excretion rates showed little to no sex difference, and excreted concentrations reached low levels by 48 hour post treatment in both males and females. The outcomes of this study can be used by health u0026 safety experts to develop evidence-based policies for risk management of handling cages and bedding of animals treated with tamoxifen and BrdU.