Communities can be polluted in several ways. Some communities undergo catastrophic exposures such as nuclear accidents; others may experiencea regular release of toxic chemicals from nearby industrial areas; and still others may receive pollution that has migrated through air and water.
Some communities experience high-level catastrophic exposures to carcinogens: Hiroshima and Nagasaki after the U.S.-detonated atomic bombs; Chernobyl and Three Mile Island after nuclear reactor accidents; Seveso, Italy, after the accidental release of dioxin from a chemical plant. In each of these cases, the mass exposures of young women and girls led to increased breast cancer rates two to three decades later (Pesatori, 2009; Pukkala, 2006; Land, 1997).
Most polluted communities, however, are not victims of single catastrophic events. Instead, they are situated near factories, waste disposal sites, agricultural areas or other pollution sources that regularly release toxic chemicals or radiation into the environment. Some, but not all, of these sources are recorded by the Environmental Protection Agency’s Toxic Release Inventory (TRI) database. TRI facilities are more likely to be located near communities with higher proportions of people of color and people with lower socioeconomic status (Perlin, 2001; Mohai, 2009). In many cases, sources of pollution are clustered in a small area, meaning that communities near one toxic release site are often near several others (Perlin, 2001). Research suggests that exposures to mixtures of chemicals may magnify risk. The disparities in proximity to pollution sources motivated the emergence of the environmental justice movement, which seeks to establish fair and equal access to environments free of pollutants and fair and equal participation in environmental decision-making (IBCERCC, 2013; Cole and Foster, 2001).
Since many pollutants make their way into water or air, which allows them to travel long distances, contamination is not limited to the immediate source of the problem although exposure levels are higher closer to factories and waste disposal sites. Nevertheless, pollutants may accumulate at significant levels in areas far from where they are used. For instance, some chemicals tend to move more easily into colder climates (Wania, 1993). As a result, animals and humans in colder parts of the world — often in areas of the world that are less industrialized — can experience very high levels of exposure to chemicals from thousands of miles away.