The report and data are
posted online.
PEMBROKE, N.H. –Nearly 40 percent of New Hampshire's bedrock groundwater likely
contains at least low levels of naturally occurring arsenic, according to a new
U.S. Geological Survey report.
Groundwater supplies likely to have
high arsenic levels can be found in scattered locations throughout the state,
but are more frequent in densely populated Merrimack, Rockingham, Stafford, and
Hillsborough counties in the southeast, the findings and accompanying maps
show.
"Arsenic is naturally occurring
in the bedrock of New Hampshire, and under certain conditions more or less of
it will leach from the rocks into the groundwater that people drink, making it
a human health hazard if left untreated," said USGS Director Marcia
McNutt. "The contribution from this new study is that it alerts people
across the state who may not previously have thought that they were at any risk
that it would be wise to get their water tested."
Arsenic levels are largely
controlled by bedrock type and by fractures, but are associated with other
factors including groundwater chemistry, hydrology, topography, land use and
demographics, according to the study done in cooperation with the New Hampshire
Departments of Health and Human Services, and Environmental
Services.
"We knew from previous studies
that arsenic is a regional problem in New Hampshire, but we were surprised that
low arsenic levels are widespread across the state," said USGS scientist
Joe Ayotte, who led the study. Previous USGS studies have shown private
groundwater wells in New Hampshire may have arsenic at concentrations close to
or above health-based safety standards for public water supplies.
"Arsenic in ground water used
for private or a public water supply is a public health concern in New
Hampshire," said the state’s public health director, Dr. Jose
Montero. "To protect families, the State of New Hampshire recommends
that private well owners test their drinking water for arsenic every
three-to-five years."
Arsenic in drinking water has been
linked to several types of cancer, reproductive problems, diabetes, a weakened
immune system, and developmental delays in children. Arsenic can be
reduced or eliminated in tap water through treatment. Private well owners
can find information on well testing
and treatment
online.
"The geology and fractures in
New Hampshire's bedrock are complex, so homeowners should not rely on the
results from neighboring wells to determine if their own well water is
safe," Ayotte explained. "The data are intended to inform
public health research and decision makers, and may be useful to medical
practitioners where patients rely on private wells for drinking water."
"This mapping project is
intended to help planners and health officials understand the widespread nature
of certain contaminants in New Hampshire's drinking water," said Matthew
Cahillane, Program Manager of the New Hampshire Environmental Public Health
Tracking Program. "It provides a very useful picture of where arsenic
levels might be higher or lower in groundwater. We hope the results also
encourage all well owners to test their individual water supplies."
The information will become part of
the collection of data assembled and housed by the Public Health Tracking
Program, which was initiated and funded by the Centers for Disease Control and
Prevention.
Private wells supply drinking water
for about 40 percent of the population of northern New England and bedrock
aquifer wells – often known as rock, deep, or artesian wells – are the most
common type of well installed for homes in the state. Bedrock groundwater
is the main source for the region's drinking water supplies.
Health Information Summaries on
arsenic can be found online: