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. |