Contaminants

Contaminants are substances found in air, water, soil, food, or consumer products where they are not intentionally present and where their presence may degrade quality, safety, or function. They may originate from natural processes, human activities, or accidental releases and can differ in duration and concentration.

Chemical contaminants include heavy metals such as lead and mercury; pesticides; solvents; salts; and industrial byproducts. Biological contaminants include bacteria, viruses, fungi, and parasites. Physical contaminants include foreign materials such as glass, plastics, or inert particles like sand.

Common sources include industrial discharges, agricultural runoff, improper waste disposal, processing and manufacturing, and natural geological leaching. Exposure occurs mainly through ingestion, inhalation, or dermal contact and may pose acute or chronic health risks depending on dose and duration.

Regulators establish limits or guidelines for contaminants in drinking water, food, air, and workplaces. Measurement involves sampling and laboratory analysis; risk assessment informs permissible levels and remediation strategies.

Remediation includes treatment technologies such as filtration, coagulation, adsorption, chemical oxidation, and biodegradation, as well as source control and cleanup. Prevention emphasizes monitoring, compliance with standards, best practices in manufacturing and waste management, and substituting safer materials.

Some contaminants persist in the environment and may bioaccumulate, affecting ecosystems and wildlife. Contaminants pose challenges for public health, environmental protection, and product safety, prompting ongoing research, monitoring, and policy development to reduce exposure and mitigate harm.