VOCs Turn Up in Well Water
Sensitive Measure Reveals Groundwater Contaminant
About 15% of the U.S. population get their drinking and household
water from a largely unmonitored source: private residential wells.
About 400,000 new wells are drilled every year. A new USGS study
suggests that the water in a small percentage of domestic wells could
contain unsafe levels of volatile organic compounds (VOCs)
[
EHP 115:1539–1546; Rowe et al.].
VOCs come from a wide variety of sources, including gasoline,
plastics, paints, dyes, solvents, adhesives, insecticides, and spot
removers, and have wide-ranging health effects. The chemical and
physical properties of VOCs allow the compounds to move between the
atmosphere, soil, surface water, and groundwater. Once in the
environment, some VOCs degrade quickly whereas others persist for
decades.
The USGS collected data on 55 VOCs primarily
between 1991 and 2002. The team analyzed water samples before
homeowners treated or filtered the water, which could help reduce VOCs.
Many—possibly half of all well users—don't filter their water. The
wells ranged in depth from 6 to 1,500 feet, with a median depth of
about 140 feet. Of the 2,401 wells studied, 65% had detectable levels
of VOCs, and 1% had levels above the EPA maximum contaminant level for
the compound(s) observed. The most common compounds found were
chloroform, toluene, 1,2,4-trimethylbenzene, and perchloroethene.
Factors associated with the presence of VOCs were
dissolved oxygen content, precipitation, the presence of a hazardous
waste site within 1 km of the well, aquifer type, and water
temperature. The authors note that identifying factors associated with
VOC occurrence may aid in understanding the sources, transport, and
fate of these compounds in groundwater.
Originally published on http://www.ehponline.org
