An exposure pathway refers to the way in which a person may
come into contact with a hazardous substance, whether it is a
chemical, biological, or some other harmful substance. There are
three basic exposure pathways: inhalation, ingestion, or direct
contact. The degree or extent of exposure is determined by
measuring the amount of the hazardous substance at the point of
contact, whether that contact occurs in the lungs of someone who
has breathed in the hazard, the stomach lining of someone who has
eaten it, or the skin of someone who has touched it.
Health and ecological hazards
can result from such exposures.
Some common ways in which people may become exposed to
hazardous substances include the following:
-
Groundwater and Surface Water. Exposure will
occur if people drink contaminated groundwater or
surface water, accidentally ingest it while
swimming, or if it comes into contact with their skin
(e.g., in the shower, while swimming, etc.).
-
Soil, Sediment, Dust. People will be exposed to
hazardous substances in soil, sediment, or dust if
they accidentally ingest it (e.g., the contaminants
land on their food), if they breathe it in (especially
dust), or if their skin comes into direct contact with
the contaminated materials. Because of their play
habits, children are highly susceptible to exposure
through these pathways.
-
Air. When the hazardous substance takes the form
of vapors or is absorbed by particulate matter (e.g.,
dust), the simple act of breathing can expose people
to contamination. In some cases, a person's skin
can absorb a hazardous substance in vapor form,
although inhalation is considered the greater threat.
-
Food. Eating food that has been contaminated is
another common exposure route. In some cases,
food found on people's plates may be contaminated
as a result of direct exposure to the hazardous
substance. In other cases, food contamination may
occur further down the food chain. For example,
hazardous substances can collect in the fatty tissues
of animals that ingest contaminated plants. The
contamination can then be transferred to the
animals' natural predators, and eventually, to
people.
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