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Table 1 Examples of sources and pathways of human exposure to a few selected chemicals

From: Knowns and unknowns on burden of disease due to chemicals: a systematic review

Exposure media Example sources of exposure and exposure pathways Examples of chemicals
Outdoor air Inhalation of toxic gases and particles from vehicle and industrial emissions, or naturally occurring sources such as volcanic emission or forest fires. Sulfur dioxide, nitrogen oxides, ozone, suspended particulate matter, lead, benzene, dioxins and dioxins-like compounds
Indoor air Inhalation of pollutants released during indoor combustion of solid fuels, tobacco smoking, or from construction materials and furnishings, contaminants in indoor air and dust. Suspended particulate matter, nitrous oxide, sulfur oxides, carbon monoxide, formaldehyde, polyaromatic hydrocarbons (PAH), mercury, lead dust from lead-based paints, benzene, asbestos, mycotoxins, phtalates, polybrominated diphenyl ether fire retardants (PBDEs)
Drinking water Ingestion of drinking water contaminated with toxic chemicals from industrial effluents, human dwellings, agricultural runoff, oil and mining wastes, or from natural sources. Pesticides, herbicides, fertilisers, metals (copper, lead, mercury, selenium, chromium), arsenic, fluoride, nitrate, cyanide, industrial solvents, petroleum products, disinfection by-products.
Food Consumption of food contaminated with chemicals at toxic levels through agricultural practices, industrial processes, environmental contamination, and natural toxins. Pesticides, methylmercury, lead, cadmium, dioxins, aflatoxin.
Non-food consumer products Exposure by ingestion, inhalation or dermal exposure to toxic chemicals contained in toys, jewellery and decoration items, textiles, or food containers, consumer chemical products Lead, mercury, cadmium, phthalates, formaldehyde, dyes, fungicides or pesticides.
Soil Ingestion (particularly for children) or inhalation of soil contaminated through industrial processes, agricultural processes or inadequate household and industrial waste management. heavy metals, pesticides, and persistent organic pollutants.
Occupational exposure Chronic or acute exposures through inhalation, dermal absorption, or secondary ingestion of toxic chemicals or by-products of industrial processes such as agriculture, mining or manufacturing. Pesticides, benzene, heavy metals, solvents, suspended particulate matter.
Human to human Foetal exposure to toxic chemicals during pregnancy (through placental barrier) or through consumption of contaminated breast milk. Heavy metals, pesticides, benzene, etc.