‘ toxicology ’

Toxicology is the scientific study of the adverse effects of chemical, biological, and physical agents on living organisms and the environment. It encompasses the detection, assessment, understanding, and prevention of harmful exposures, drawing on disciplines such as biology, chemistry, pharmacology, and medicine. The field plays a critical role in public health, environmental protection, regulatory science, and risk assessment.

Toxicologists examine how substances cause harm, the mechanisms behind these effects, and the conditions under which such effects occur. Key concepts include:

• Dose-response relationship: A fundamental principle that the severity of an effect depends on the dose; “the dose makes the poison” is a guiding maxim.
• Exposure routes: Includes ingestion, inhalation, dermal contact, and injection, each influencing the absorption and toxicity of a substance.
• Toxicokinetics and toxicodynamics: Study how substances move through and interact with the body (absorption, distribution, metabolism, and excretion) and how they exert their biological effects.

Toxicology is essential for evaluating the safety of pharmaceuticals, chemicals, food additives, industrial materials, and environmental contaminants. Regulatory agencies such as Health Canada, the U.S. Environmental Protection Agency (EPA), and the European Chemicals Agency (ECHA) rely on toxicological data to set exposure limits and guide risk management decisions.

Applications in Risk Assessment:

• Identifying hazardous properties of substances
• Estimating exposure levels in populations
• Informing quantitative risk assessments and the establishment of reference doses or thresholds

Through its integration into risk science, toxicology supports evidence-based decision-making to protect human health and ecosystems.