Exposure is the state of being unprotected. It is a set of conditions that allows a pollutant or contaminant to enter the human body. The presence of pollution, the medium that the pollutant is in and the human subject or host that will be affected by the pollutant are the set of conditions used to describe the exposure. In the Minamata example, the source was the Chisso factory, the medium was the water and the subjects were the people who consumed contaminated fish.

There are three main routes by which people are exposed to pollution. These are:

• Ingestion: in the Minamata example people ingested contaminated fish.
• Inhalation: repeatedly breathing in air pollutants can cause respiratory diseases.
• Skin contact (also called dermal exposure): direct contact, usually with the hand, in which chemicals penetrate the skin and enter the circulatory system.

Figure 8.8 indicates the possible exposure routes for pollutants and links from source to recipient.

Figure 8.8 Exposure routes of pollutants.