Final answer:
A person's genetic characteristics are not typically included in standard toxicity assessments such as lethal dose measurements, which focus on the dose and its effects as demonstrated by the dose-response curve.
Step-by-step explanation:
When considering the degree of toxicity of a substance, a person's genetic characteristics is not typically one of the variables considered. Toxicity assessments focus on factors such as the dose, exposure route, animal species tested, and environmental conditions rather than individual genetic traits. However, it is recognized that genetics can influence how an individual responds to a toxic substance, but these differences are generally not accounted for in standard toxicity measurements like the lethal dose (LD50).
The concept of lethal dose is an indicator of a substance's toxicity. As exemplified by the dose-response curve, this measures the relationship between the dose of a substance and the severity of the response in the individual. Small amounts of certain elements like selenium are necessary for health, but in larger doses, they can be toxic or even carcinogenic.