Monday, May 11, 2009

Great Lakes Initiative GLI Human Health Based Criteria

What is a Human Health-based Water Quality Criterion?

The Water Quality Guidance for the Great Lakes System, also known as the Great Lake Initiative or GLI (40 CFR 132), created a few new types of water quality standards intended to be applied to waters in the Great Lakes basin.

A Great Lakes Water Quality Human Health-based Criterion (HHC) is intended to protect humans from unacceptable exposure to toxicants via consumption of contaminated fish and drinking water and from ingesting water as a result of participation in water-oriented recreational activities. The criteria were developed to provide a level of protection likely to be "without appreciable risk" of carcinogenic and/or noncarcinogenic effects.

Chemical concentration levels protective of human health are derived based on either a Tier I (“Tier I Criterion”) or Tier II (“Tier II Value”) classification. The two Tiers are primarily distinguished by the amount of toxicity data available for deriving the concentration levels and the quantity and quality of data on bioaccumulation.

For known or suspected carcinogenic chemicals, the criterion are derived at a level corresponding to an incremental cancer risk of 1 in 100,000. Noncarcinogens are generally assumed to have a threshold dose or concentration below which no adverse effects should be observed. The Tier I criterion or Tier II value is the maximum water concentration of a substance at or below which a lifetime exposure from drinking the water, consuming fish caught in the water, and ingesting water as a result of participating in water-related recreation activities is likely to be without appreciable adverse effects.

Human-health based water quality criteria were derived for 17 compounds (see below); however, the GLI detailed the methodology to derive human health-based criteria for other compounds.

Methylene chloride

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address water quality standards, wastewater permitting and assessing potential impacts of chemicals in the aquatic environment.

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