Which factor is a key determinant of individual susceptibility to toxic substances?

Genetic predisposition is a fundamental factor that determines individual susceptibility to toxic substances. This aspect refers to the inherited characteristics that affect how a person's body metabolizes and responds to chemicals. Variations in genes can influence various biological processes, such as the efficacy of detoxification enzymes, the integrity of cellular membranes, and the repair mechanisms for damaged DNA.

For example, some individuals may have genetic variations that make them more efficient at breaking down toxins, while others may carry mutations that impair their ability to do so. This genetic variability can result in diverse responses to the same toxic exposure—some individuals may experience severe effects, while others might be relatively unaffected. Understanding the role of genetic predisposition is essential in toxicology, as it highlights why certain populations may be more at risk for adverse effects from specific substances.

The other factors listed, while they may influence exposure and risk levels, do not have the same direct impact on individual biological responses as genetic predisposition does.