contaminated

Contaminated is an adjective describing something that has been made impure, polluted, or unsafe by the introduction of an unwanted substance. The substance causing contamination is called a contaminant. Contamination can be chemical, biological, radiological, or physical, and it may affect air, water, soil, food, or surfaces. The term is used across many fields, including environmental science, food safety, healthcare, and industrial quality control.

Common forms include environmental contamination (pollution of air by particulates, water by chemicals or pathogens, soil by metals or solvents), food contamination (pathogens, toxins, foreign materials), and laboratory or medical contamination (microbial or chemical intrusion that compromises samples or procedures). Contamination can occur accidentally through spills, leaks, or improper handling, and in some cases intentionally as contamination or adulteration.

Assessment typically involves sampling and laboratory analysis to determine contaminant type and concentration, followed by risk assessment and regulatory thresholds. Control measures include containment, decontamination, cleaning, proper sanitation, and preventive practices. The related terms include contaminant (the substance causing contamination), decontamination (removal of contamination), and contamination control (systems and procedures to minimize risks).