Exposure Pathways and Routes

Exposure Routes

Once a chemical, physical or biological agent reaches us, the exposure route is the way it enters our body. The three major exposure routes to humans are:

Other exposure routes are placental exposure of a fetus, exposure to noise, and eye exposure to ultraviolet (UV) radiation.

Exposure Pathways

The exposure pathway is the physical course an environmental agent takes from its source to those who eventually receive it. For example, agricultural use of pesticides may contaminate crops, the soil, and the air. Some pesticide remains on crops when they are harvested and distributed. Eventually, the food (and the pesticide) are ingested by a human.

An exposure pathway: Agricultural use of a pesticide contaminates crops, which are harvested and sold as food which is eventually ingested.  

The illustration below summarizes a variety of possible exposure pathways.

Various exposure pathways: gaseous agents can be deposited on crops and in soil and then ingested by cattle or humans, or they can enter the water supply or by inhaled

Image source: http://www.atsdr.cdc.gov/hac/pha/PHA.asp?docid=78&pg=2 

A key aspect of an exposure pathway investigation is a determination of how people in a community might come into contact with a chemical. In an exposure pathways evaluation, five main elements are considered:

  1. Contaminant source: Place where the chemicals originated or were released
  2. Environmental fate and transport
  3. Specific location(s) where people may come in contact with a chemical in the environment
  4. Exposure route: How the contaminants enter one's body (inhalation, ingestion, dermal absorption)
  5. Estimate of the number of potentially exposed people

return to top | previous page | next page