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USGS News Release: Man-Made Chemicals Found in Drinking Water at Low Levels

News Release

U.S. Department of the Interior
U.S. Geological Survey

For release:  December 5, 2008

Greg Delzer, 605-394-3230, gcdelzer@xxxxxxxx
Jennifer LaVista, 202-380-6052, jlavista@xxxxxxxx

Man-Made Chemicals Found in Drinking Water at Low Levels

Low levels of certain man-made chemicals remain in public water supplies
after being treated in selected community water facilities.

Water from nine selected rivers, used as a source for public water systems,
was analyzed in a study by the U.S. Geological Survey (USGS).

“Most of the man-made chemicals assessed in the USGS study are unregulated
in drinking water and not required to be monitored or removed,” says Tom
Jacobus, General Manager of the Washington Aqueduct. “These findings are
not surprising and they will be important in helping regulators and
assisting water utility managers arrive at decisions about future water
treatment processes.”

Scientists tested water samples for about 260 commonly used chemicals,
including pesticides, solvents, gasoline hydrocarbons, personal care and
household-use products, disinfection by-products, and manufacturing
additives. This study did not look at pharmaceuticals or hormones.

Low levels of about 130 of the man-made chemicals were detected in streams
and rivers before treatment at the public water facilities (source water).
Nearly two-thirds of those chemicals were also detected after treatment.
Most of the chemicals found were at levels equivalent to one thimble of
water in an Olympic-sized pool.

“Low level detection does not necessarily indicate a concern to human
health, but rather indicates what types of chemicals we can expect to find
in different areas of the country,” said USGS lead scientist, Gregory
Delzer. “Recent scientific advances have given USGS scientists the
analytical tools to detect a variety of contaminants in the environment at
low concentrations; often 100 to 1,000 times lower than drinking-water
standards and other human-health benchmarks.”

Testing sites include the White River in Indiana; Elm Fork Trinity River in
Texas; Potomac River in Maryland; Neuse River in North Carolina;
Chattahoochee River in Georgia; Running Gutter Brook in Massachusetts;
Clackamas River in Oregon; Truckee River in Nevada; and Cache La Poudre in
Colorado. The populations in communities served by these water treatment
plants vary from 3,000 to over a million.

This study is among the first by the USGS to report on a wide range of
chemicals found before and after treatment. The full source-water quality
assessment ( http://water.usgs.gov/nawqa/swqa ) and listing of chemicals
are available online.

Chemicals included in this study serve as indicators of the possible
presence of a larger number of commonly used chemicals in rivers, streams,
and drinking water. The most commonly detected chemicals in the source
water were herbicides, disinfection by-products, and fragrances. Many of
these chemicals are among those often found in ambient waters of 186 rivers
and streams sampled by USGS since the early 1990s, and are highly
correlated with the presence of upstream wastewater sources or upstream
agricultural and urban land use. About 120 chemicals were not detected at

Measured concentrations of chemicals detected in both source and treated
water were generally less than 0.1 part per billion. Although potential
human-health effects and risk were not assessed in this study, adverse
effects to human health are expected to be negligible based on comparisons
of measured concentrations and available human-health benchmarks.

More than 75 percent of source- and treated-water samples in this study
contained 5 or more chemicals. The common occurrence of chemical mixtures
means that the total combined toxicity may be greater than that of any
single contaminant present. The USGS report identifies the need for
continued research because the additive or synergistic effects on human
health of mixtures of man-made chemicals at low levels are not well
understood. The study also did not look at implications to ecosystems or
aquatic health.

USGS findings are used by the U.S. Environmental Protection Agency, the
States, utilities and many nongovernmental agencies to help protect streams
and watersheds that serve as water supplies and to guide those involved in
decisions on treatment processes in the future.

The USGS is a non-regulatory agency which often monitors the quality of
available, untreated water resources. These studies begin to relate the
quality of these resources to drinking water. USGS studies are intended to
complement drinking-water monitoring required by Federal, State, and local
programs, which focus primarily on post-treatment compliance monitoring.

The USGS National Water-Quality Assessment Program is planning to complete
as many as 21 additional surface-water assessments through 2013 (
http://pubs.usgs.gov/fs/2007/3069/ ). A companion study is scheduled for
release in 2009 that summarizes the occurrence of the same chemicals in
high-production wells and the associated treated water in 13 states.

USGS provides science for a changing world. For more information, visit

Subscribe to USGS News Releases via our electronic mailing list at
http://www.usgs.gov/newsroom/list_server.asp or our RSS feed at

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