What it is:

• Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids.
• VOCs have inherent physical and chemical properties that allow these compounds to move between water and air.
• VOCs have been used extensively in the U.S. since the 1940s. Some VOCs, such as chlorinated solvents, have been used in commerce and industry for almost 100 years.

Occurrence:

• Some VOCs may occur naturally in the environment, other compounds occur only as a result of manmade activities and some compounds have both origins.
• VOCs are emitted from a number of products, including paints, paint strippers, cleaning supplies, pesticides, air fresheners, hobby supplies and permanent markers.
• In 2010, the U.S. Geological Survey announced the results of its "National assessment of volatile organic compounds." Samples from 3,498 wells in 98 aquifer studies that were collected during 1985-2002 were analyzed for 55 VOCs. About 19 percent of the samples contained one or more VOCs at an assessment level of 0.2 µg/L.

Health effects:

• VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects, such as: Eye, nose and throat irritation; headaches and loss of coordination; and damage to the liver, kidney and central nervous system.
• The presence of elevated VOC concentrations in drinking water may be a concern to human health because of their potential carcinogenicity.

Regulation:

• The U.S. Environmental Protection Agency (EPA) has established Maximum Contaminant Levels (MCLs) that apply to 29 VOCs in drinking water supplied by public water systems.
• Some states have set MCLs for additional VOCs and in some cases have established more stringent standards than EPA.

Water treatment:

• Activated carbon and aeration are effective at reducing VOCs.

Sources: U.S. Environmental Protection Agency, U.S. Geological Survey.