The determination of safe levels of exposure to potentially poisonous substances for humans and the environment is a fundamental goal of toxicology. Adverse effects result from interactions of the chemical with critical receptors in the organism, the extent of which depends on the exposure level but often on exposure time as well. Time-dependent toxicity occurs when the receptor binding is either slowly reversible or irreversible, and cumulative effects may also occur under such conditions. However, dose-time-response studies to demonstrate time-cumulative toxicity are rarely conducted.
Tennekes HA. Novel approaches to chemical risk assessment. Environ Risk Assess Remediat. 2017;1(3):1-2