Final answer:
A toxicologist is an expert in toxicology, the study of harmful effects of substances on organisms and the environment, focusing on preventing and reducing these adverse effects.
Step-by-step explanation:
A toxicologist is a specialist in the field of toxicology, which is the scientific study of the adverse effects of chemical, physical, or biological agents on living organisms and the ecosystem. This discipline involves examining how environmental toxins affect health, and the development of measures to prevent or minimize damage caused by these substances. Toxicologists conduct research to understand how substances exert their harmful effects, establish safe exposure levels, and design strategies to mitigate toxic risks to individuals and the environment. One key concept in toxicology is the dose-response relationship, illustrating how the dose determines the toxic effect on an organism. For example, while a small amount of selenium is necessary for bodily functions, an overdose may lead to severe health issues, such as cancer.