toxicita

Toxicity, in Czech and Slovak, is a term used to describe the degree to which a substance can cause adverse biological effects in living organisms. Toxicity encompasses chemicals, drugs, and environmental agents and depends on dose, exposure duration, route of entry, species, and individual susceptibility.

Toxicity is categorized by duration (acute vs chronic) and by affected systems (systemic vs local). Acute toxicity refers to harmful effects following a short-term exposure; chronic toxicity results from long-term or repeated exposure. Other distinctions include hepatotoxicity, nephrotoxicity, neurotoxicity, and cardiotoxicity. Toxicity is assessed through dose–response relationships; LD50 is a traditional measure in animal studies, though modern assessments favor NOAEL/LOAEL and other endpoints. Toxicokinetics describe absorption, distribution, metabolism, and excretion; toxicodynamics describe the interaction of the substance with biological targets and the resulting effects.

Exposure pathways include inhalation, ingestion, and dermal contact. Toxic effects can be influenced by mixtures, with synergistic, antagonistic, or additive interactions. Bioaccumulation and biomagnification can extend effects in ecosystems. Ecotoxicology studies impacts on wildlife and the environment, complementing human toxicology.

Risk assessment combines hazard identification, dose–response assessment, exposure assessment, and risk characterization. Regulatory frameworks establish exposure limits and safety standards to protect health and the environment, guiding industrial, occupational, and consumer safety.

Common examples of toxic substances include lead, mercury, aflatoxins, cyanide, organophosphate pesticides, and certain mycotoxins. Some substances can be therapeutic at controlled doses but harmful at higher levels, illustrating the importance of dose in toxicity.