UPI | Nitrates in U.S. wells worrisome
WASHINGTON, March 21 (UPI) — A federal government report on nitrate contamination of the nation’s ground-water supplies shows about 7 percent of U.S. wells contain potentially hazardous levels of the substance — although the data used to compile
the report are far from comprehensive.
The report, compiled by the U.S. Geological Survey’s National Water-Quality
Assessment Program, attempted to determine nitrate and pesticide levels in select wells
across the country.
About 40 million Americans rely on wells for their household water.
Nitrates, the product of fertilizers and livestock manure, seep into the ground and mix
with water in aquifers, contaminating them. Though nitrates also occur naturally, human
agricultural activities have thrown off the natural balance, causing large volumes to
permeate the soil and waterways.
Nitrate contamination may be linked to health problems such as methemoglohinemia —
also known as blue-baby syndrome — as well as type-1 diabetes, neural-tube defects, and
bladder, stomach and colon cancer, according to Mary Ward, an epidemiologist at the
National Cancer Institute in Bethesda, Md.
“We really need more studies to see if the results are consistent,” Ward said of the
NWQAP document. “Many of these studies simply weren’t large enough or were directed
at very specific groups of people.”
One obstacle to nationwide ground-water monitoring has been that the Environmental
Protection Agency lacks the authority to study domestic wells, which are not covered by
the Safe Drinking Water Act. So Congress funded NWQAP in 1991 — under USGS
auspices — to investigate water-quality issues throughout the United States.
“We see nitrates more often than any other contaminant, and that has us concerned,” said
Donna Myers, NWQAP’s director.
In recent years, many local governments and citizen organizations have organized nitrate-
monitoring and public-education programs that specifically target ground-water
contamination, said Roy Simon, chief of the prevention branch of EPA’s Ground Water
and Drinking Water office.
“In agricultural areas or areas with shallow water, people intuitively know about it,”
Simon said. “There’s a lot coming out of Nebraska and we work with these groups and
they work with the farmers.”
The USGS effort began as a low-cost way of finding and measuring ground-water
contamination, Myers said. It used data collected from about 1,200 of the agency’s own
wells nationwide and combined that information in a computer model with statistics
collected elsewhere on sources of nitrogen and known factors that affect the spread of
Local USGS offices provided data from their wells and agency officials conducted the
modeling at the agency’s headquarters in Reston, Va.
The USGS model has helped to target areas of nitrate contamination and help discover
the contamination’s sources, said Bernard T. Nolan, a hydrologist with the agency.
So far, the model has identified the highest-nitrate areas as the High Plains of
northeastern Nebraska, the upper Midwest, northwestern Texas and parts of the Mid-
The agency also has worked with state water-quality offices and local groups that
monitor nitrate levels to help improve the accuracy of its predictions, Myers said. The
result: the USGS data are correct in about three out of four cases.
“Models are only successful if they are verified with ‘on the ground’ measurements,”
Such measurements include the depth of and soil conditions around wells. The deeper the
well, the less likely nitrates have seeped into the ground water. Soils and loose rocks that
drain often will help to reduce contamination as well, because the nitrates will wash away
on the surface instead of seeping into the ground, he said.
“Southern Indiana is highly fertilized, but doesn’t have high nitrate levels,” Nolan said.
As urban sprawl spreads farther into rural communities, the number of people using
ground water is increasing, Myers said. These wells are often shallow, leaving them at
higher risks for contamination, she added.
Regional USGS scientists are working with state groups to make predictive models using
the same techniques as NWQAP to predict nitrate, arsenic and specific fertilizer
In New England, the National Cancer Institute, Dartmouth University and several state
departments of health are working to measure arsenic in ground water and its possible
connection to rates of bladder, kidney, lung and skin cancer. Some research has found
that new communities built on certain types of bedrock are more likely to be drinking
water with elevated arsenic levels.
NCI epidemiologist Debra Silverman noted, however, that it generally takes high levels
of arsenic to harm people.
“We see the effects of large levels in Taiwan, Argentina and Chile, but the effects of low
levels are really not established,” Silverman said. “Levels in the United States are still
Next year, Myers said, NWQAP plans to release a next-generation study with a larger
sample of wells — perhaps as many as 4,000 — with additional information on how to test
wells in arid areas where water evaporates quickly. Such areas are more likely to be
absent from ground-water studies, she added.
Myers said the current NWQAP study has been submitted for peer review.
Lisa Pickoff-White is an intern for UPI Science News. E-mail: firstname.lastname@example.org
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