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How Can People be Exposed to Contaminants at Former MGP Sites?

In general, people can be exposed to MGP wastes through three major routes:

  • breathing (also called inhalation),
  • eating or drinking (also called ingestion), and
  • getting something on the skin (also called dermal contact).

Exposure refers to people contacting a chemical. For more information on what exposure means, you can read the NYS DOH fact sheet on exposure at their website

People can be exposed to MGP contamination including; tar, tar-contaminated soils, purifier waste, contaminated groundwater or surface water, contaminated dust and contaminated air. If there is no contact with wastes, there is no exposure.

Soil and Wastes

Most MGP sites have been inactive for several decades, and many have been redeveloped for other uses. MGP wastes that were present on the surface when the plants were operational have often been removed or covered by buildings, pavement, or soil. Consequently, MGP wastes are often not on the ground surface where people on the property will come into contact with them. However, if there are wastes on the surface, or if people dig into waste or contaminated soil and bring it to the surface, exposure through dermal contact and accidental ingestion can occur. Also, if vegetables are grown in contaminated soil, people may ingest contaminants when they eat the vegetables.

Contaminated Drinking Water and Surface Water

MGP waste can contaminate groundwater. The contamination can then migrate and affect public or private drinking water wells in the area. People can be exposed to contaminants in their water supply by drinking and showering with it (inhalation and dermal contact exposure). Public water supplies are monitored for contamination under NYS DOH regulations and, if contaminated, are removed from service or treated to comply with drinking water standards.

MGP wastes occasionally contaminate surface water, where they can float on the surface or sink to the bottom and contaminate sediment. If people play, swim or wade in these waters, they may be exposed to contaminants through accidental ingestion and dermal contact. Also, if fish living in contaminated waters are caught and eaten, people can ingest MGP contamination.


Both tar and purifier wastes contain volatile chemicals that can vaporize and be inhaled. People who dig into wastes may be exposed to vapors from the waste. Also, vapors from MGP wastes can migrate through soil into the air in buildings, where people could breathe them.

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