Title: Nitrates and Groundwater, Brochure
Full Citation
Permanent Link: http://ufdc.ufl.edu/WL00002204/00001
 Material Information
Title: Nitrates and Groundwater, Brochure
Physical Description: Book
Language: English
Publisher: Freshwater Foundation
Spatial Coverage: North America -- United States of America -- Florida
Abstract: Nitrates and Groundwater, Brochure
General Note: Box 10, Folder 9 ( SF Water Quality-Significant Numbers - 1990's ), Item 1
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: WL00002204
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text



A Public Health

Developed by
the Freshwater Foundation's
Health and Environment Network a


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Copyright, 1988 Freshwater Foundation
Funding for this brochure was provided by a grant from the Patrick and
Aimee Butler Family Foundation.
Published and edited by the Freshwater Foundation for its Health and
Environment Network.
The Freshwater Foundation is a nonprofit, nonadvocacy organization
which supports research and.lublic information programs on all
aspects of freshwater issues.'.
The Health and Environmet# Network is a national information
exchange among medical ad other health professionals on new pro-
grams, rerts, research andissues of a" environmental health nature.
The Network provides information though a monthly newsletter,
conferences and related publications. For more information on the
Network, contact the Freshwater Foundation.

Freshwater Foundation, 2500 Shadywood Road, Box 90, Navarre, Minnesota 55392.

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Nitrates and Groundwater:
A Public Health Concern

A clean, safe supply of drinking water is one of the cornerstones of
good public health. In this country we are so accustomed to a safe,
plentiful supply of water that we sometimes ignore possible threats to
that supply until they become public health problems.
One such threat to public health comes from nitrates. When drinking
water from private wells is contaminated with nitrates, formula prepared
with that water can cause a life-threatening condition called
methemoglobinemia in infants. There is also concern that long-term
exposure to nitrates in drinking water may cause the development of
cancer in adults as well.

What Are Nitrates and How Do
They Get into the Groundwater?

N itrogen is an element essential to living matter. It occurs naturally
in the environment in soil, in air, in water and even in rain.
Nitrogen occurs in many forms, including ammonia and nitrate.
Ammonia is present in the waste of both humans and animals. It can
enter the soil from inadequate or poorly managed septic systems, animal
feedlots or manure storage facilities. Microorganisms then convert it to
nitrate. To improve crop yields, farmers apply fertilizers that contain
nitrogen. This nitrogen is also converted to nitrate in the soil.
When more nitrate accumulates than the plants growing in the soil can
use, water from irrigation, rain and snowmelt can carry it down through
the soil into the groundwater. This process is called leaching. How fast
leaching occurs depends on the type of soil. Water moves rapidly
through sand or gravel or where porous limestone bedrock underlies
shallow soil.

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How Much Nitrate
Is Too Much Nitrate?
T he United States Environmental Protection Agency and the United
States Public Health Service have recommended a maximum level
of nitrate concentration in drinking water that they regard as safe for
human consumption. That level or "standard" is 10 milligrams per
liter of nitrate-nitrogen (N03-N) or its equivalent of 45 milligrams per
liter of nitrate (NO3).
More frequent reports of high nitrate concentrations in drinking water
supplies have triggered mounting concern among health professionals.
Health officials must be aware of the health implications of excessive
nitrate exposure and they must.be prepared to identify potential prob-
lems and take appropriate action when nitrate levels create a health risk.

How Common Is Nitrate
Contamination of Drinking Water?
A number of recent studies have found increasing problems with
nitrates in drinking water. In the early 1980s, a survey by the United
States Environmental Protection Agency reported that 2.7 percent of the
nation's rural water supplies, serving 603,000 households, had nitrate
levels above the standard. A 1985 U.S. Geological Survey study found
that 6 percent of the nation's rural wells exceeded the standard.
In the spring of 1984, more than 40 public water supplies in Iowa
exceeded the drinking water standard for nitrates. Washington County,
Illinois, had a nitrate concentration (NO3-N) of more than 10 mg/liter
in 81 percent of 221 dug wells and 34 percent of drilled wells. About 25
percent of private water supplies in Iowa, Kansas and South Dakota
exceed the current nitrate standard.
* mE mm:iu. m u m iu n uu m

How Does Nitrate Affect
Human Health?
N itrate itself is relatively nontoxic to humans. Health problems
associated with nitrate result primarily after nitrates enter the body,
where bacteria convert nitrate to nitrite. Nitrite can cause a condition
called methemoglobinemia.

What Is Methemoglobinemia?
M ethemoglobinemia is caused by nitrite, the chemically active
form ofnitrogen. Relatively low acidity (high pH) makes an
infant's stomach an excellent environment for the bacteria that convert
nitrate to nitrite. When an infant consumes formula made with nitrate-
contaminated water, the bacteria in its stomach convert the nitrate into
potentially dangerous nitrite. This nitrite is then absorbed from the
infant's intestine and enters into a complex chemical reaction with the
hemoglobin in the infant's blood, changing it to methemoglobin.
(Chemically, the heme iron is oxidized from the ferrous to the ferric
form.) Once this reaction has taken place, a return to normal hemoglobin
in newborns is unusually slow.
Hemoglobin is the oxygen carrier in the blood; methemoglobin cannot
carry oxygen. (It is unable to reversibly bind the oxygen molecule.) As
more and more of the blood hemoglobin is converted to methemoglobin.
the capacity of the blood to carry essential oxygen is reduced, and
symptoms of oxygen starvation begin to occur. In extreme cases, the
infant suffocates.
Because oxygen starvation results in a bluish discoloration of the body,
methemoglobinemia has been referred to as the "blue baby" syndrome.
The correct term for this condition is acquired methemoglobinemia. Once
a baby's intestinal tract is fully developed usually after six months -
methemoglobinemia is seldom a problem.
While methemoglobinemia has other possible causes, including exposure
to aniline dyes and Vitamin K, nitrate-contaminated well water is the
most common cause. I

Why Are Infants at High Risk
of Methemoglobinemia
* The relatively low acidity (high pH) of an infant's stomach is an
excellent environment for bacteria that convert nitrate to nitrite.
* An infants' intake of fluids is very high in relation to its body weight.
* Fetal hemoglobin, the predominant form of hemoglobin in an infant's
blood up to about three months of age, is more rapidly oxidized by
nitrite than adult hemoglobin.
* The reducing enzyme systems that change methemoglobin back into
hemoglobin are not completely developed in infants.

How Common Is
Methemoglobinemia in Infants?
N itrate-contaminated well water may be an increasingly important
cause of infant illness in rural areas. The incidence of methemo-
globinemia, however, is unknown. It is not one of the diseases which
has been routinely reported to departments of health. A literature review
covering the years 1945 to 1972 described about 2000 cases worldwide,
including many infant deaths. The actual number is probably much
higher. The mortality rate among affected infants is about 8 to 10 percent
Methemoglobinemia is quite rare when nitrate levels in the water supply
are below the recommended government standards. Although the
available data do not fit an exact dose-response curve (the relationship
of the amount consumed to the symptoms produced), it is evident that
the risk of methemoglobinemia increases measurably as nitrogen
concentrations increase above the recommended maximum level. No
one knows whether subtle or chronic toxic effects might occur at lower
levels of exposure, especially at levels below those that produce clinical
Because there has been relatively little study of subclinical levels of
methemoglobinemia (levels so low that they probably are not reported
or diagnosed), little is known about how chronic methemoglobinemia
affects growth, development and general health.

How Can Methemoglobinemia
Be Prevented?
B because drinking well water with chemical or bacterial
Contamination can have serious consequences, especially for
infants and for pregnant women (because of potential risk to the fetus),
physicians and community health nurses should be alert to this
problem. Private wells should be tested to ensure their safety, especially
before using the water in preparing formula for infants. In areas where
nitrate contamination is a problem, wells should be tested regularly
because the quality of well water can deteriorate abruptly in response to
drought, heavy rainstorms, flash flooding and spring thaws. An applica-
tion of nitrogen-based fertilizer or nitrogen from any source in a nearby
field, followed by rain, can also result in a rapid change in water quality.
Special care should be taken to ensure the safety of infants who are in
poor health because methemoglobinemia can complicate existing
health problems. Cases of methemoglobinemia have been associated
with diarrhea. Public health nurses can make home visits to discuss
infant feeding with parents and help to determine whether it is safe to
use well water in preparing formula.
Boiling nitrate-codtaminated water will not make it safe. In fact, boiling will
increase the nitrate concetration in the water. When water from a private
well is contaminated with nitrates, alternative sources of safe water must
be found. Possible sources include water drawn from an existing well
that has tested safe, bottled water, water treatment, water from a new
and deeper well or water from a moniptred public water supply.

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Can Nitrates in Drinking Water
Cause Cancer?
Once nitrate has been converted to nitrite, there are many other
nitrogen compounds that can then interact with it to form com-
pounds called N-nitrosamines. Certain N-nitrosamines tested in animals
ave been found to be carcinogenic, or capable of causing cancer.
Though it is assumed that exposure to these compounds increases the
risk of cancer in humans, no one knows how much of that risk is caused
by nitrate-contaminated drinking water. There is no direct evidence that
these compounds are human carcinogens.
In agricultural settings there is concern about the relationship between
pesticide exposure and cancer. The chemical structures of many
pesticides contain nitrogen. These structures can react with nitrite in
acid conditions, such as those found in the stomach, to form highly
carcinogenic compounds. Several insecticides, herbicides and fungicides
react this way, including aldicarb, atrazine, carbaryl, carbofuran,
glyphosate and Aimazine. Wells that are highly vulnerable to surface
contamination may also be vulnerable to contamination with both
nitrates and pesticides.
The total health risk from increased exposure to nitrates is difficult to
determine, because of the two steps necessary for toxicity to develop: the
conversion of nitrate to nitrite and the subsequent reaction of nitrite
with other nitrogen-containing compounds.
Epidemiological studies scientific investigations of the elements con-
tributing to the occurrence of disease in the population have, suggested
that exposure to high levels of nitrate and nitnte may be associated with
a high incidence ofstqmach and esophageal cancer, butyslies are
Long-term, widespread exposure of the public to chemicals in drinking
water is a justifiable public health concern. However, the long-term
irtrJLaof the coexistence of nitrates, pesticides and other chemicals is
unclear. Some studies suggest patterns of risk, but clear epidemiologic
evidence is currently unavailable. Such evidence would require studying
an iatire generation of people who have been exposed to these
chemicals over a lifetime.
Without more information on the health hazards from nitrogen-
coutaining compounds, the best course of action is to take reasonable
steps thatt.ill limit human exposure. Health care professionals and
members bhe public must be concerned with both real and potential
threats to public health from nitrate exposure. They need to be aware of
the possible risk of nitrate contamination in private and community
water supplies and they must be prepared to take appropriate preventive
and corrective measures.

Can Nitrates Be Removed
from Water?
Though finding and correcting the source of nitrate contamination is
the best course of action, some reverse osmosis, ion exchange and
distillation units provide effective home treatment for removing nitrates
from the water. The'process, however, can be complicated and expensive.
Simple filters do not remove nitrates. Even those water treatment units
that can remove nitrates may require regular maintenance to operate
When high n~itelvels are found in well water, other contaminants,
especially coliform bacteria, are also often present. Most nitrate removal
equipment is pnota uate to remove these contaminants. In such cases,
constructing a aew well and correcting sources of contamination may be
better solutions.

I I 'I i I II I I I I

Why Is Nitrate Contamination
Ofteti Problem in Rural Areas?
F armersave -apecial stake in preventing nitrate contamination in
A drinti lntost nitrate-contaminated wells and most reported
casesofe occur in agriculture areas. In fact, whether
or not to use itrogen fertilizer and how much fertilizer to use are two of
the important gaapg tment decisions that a farmer has to make.
Farmers use nitrogen fertilizer to produce larger crops of better quality.
These benefits repy the fertilizer investment many times over, so it is to
a farmer's advantage to use enough fertilizer to produce them. On the
other hand, it is not economically or environmentally desirable to pro-
vide more nitrogen fertilizer than crops can use.
When soil contains-more nitrate than crops can use, the excess nitrate
moves out of the soil around the plant roots and leaches into the
groundwater. Three related factors determine the amount of excess
nitrate in the soil: climate conditions, soil type and the amount of
nitrogen fertilizer used. A farmer can't do much about climate or soil
type. The amount of fertilizer used, however, can be controlled.



How Do Uvestock Operations
Cause Nitrate Contamination?

WT hed re numbers of cattle or other animals are kept in
confined areas, for feeding, fattening or other purposes, the
resulting accumulation of manure can be a source ofnitrate
contamination in nearby wells. Especially in areas where the soil is very
porous and therefore susceptible to leaching, special care must be taken
in manure storage areas to prevent runoff. Manure should not be
disposed of or piled near wells. When used properly on adjacent
cropland, manure can economically provide plant nutrients.

What Role Do On-Site Septic
Systems Play in Nitrate
n areas without swers, on-site septic systems are usually used to
treat and dispose of household wastes. However, the typical septic
system remes little, if any, nitrogen from the waste. Whether this will
cause a nitr pobem in nearby wells depends on the number of
household a.~i h nua er of on-site sewage systems in the area, the
depth.of the twel a t of treated wastewater entering the ground-
water, the 6 ted.cooV, the direction and rate of groundwater
movement and O. .ZteA concentrations already in the groundwater.
To deal with potential prdbleits, private septic systems can be upgraded
or moved. If nitrates fwir an on-site system are a concern, sewage
treatment moua,ln be installed. These mounds can reduce nitrate
levels by as mdiih ai'45 percent
If on-site a pS 3 qPit shallow, plants growing above the system will
take up some a jp Communities can also make changes in land use
and zoning tlatstio for proper septic system design or to limit
density of seplftteas in an area.

Can Ponstruction, Location
at Mittenance of Wells
Help Protect the Water Supply?
igh nitrate levels are often associated with poorly constructed or
LI located wells. Unlike other contaminants, nitrate is not diluted
and filtered out as water travels through soil, so water wells must be
isolated from possible sources of nitrate, including both leaching and
surface drainage such as barnyard runoff. Wells should never be sited
near septic systems.
Many states have established well codes which set construction require-
ments for wells. Wells constructured to code by licensed contractors help
to protect the water supply from nitrate contamination. State and local
departments of health can supply information about well construction
and regulations.

If you have an abandoned well on your property,, make sure that it is
properly capped or sealed. Open wels can act as funnels, providing direct
access to the groundwater for surface pollutants like nitrates, organic
material and pesticides.

3 .


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An increasing number of water wells tested for nitrates exceed the
Current nitrate standard. Exposure to excessive levels of nitrates
from drinking water may lead to increased incidence of methemoglo-
binemiain iinfaits, especially those under three months of age. It may
also contribute to methemoglobinemia in susceptible adults. Although
researchers need to conduct further studies to determine the relationship
between nitrate exposure and cancer, preliminary studies indicate that
long-term exposure to nitrates may increase the incidence of various
health risks m humans.

Where Can I Go for Further

Information and Assistance?

* State or local health departments

* State departments of agriculture

* County Extehsion offices

* Personal medical cae providers


Cantor K.P.. Blair A.. Zahm S.H. Agricultural chemicals, drinking water, and public
health: An epidemiologic overiew. Annual Meeting of the Great Plains Agricultural
Council, Fort Collins. Colorado, 1987.
Evans MA Health effects from groundwater pesticides. Conference proceedings -
Pesticides and Groundwater: A Health Concern for the Midwest. St Paul, MN, 1986.
Fraser P.. Chilvers C.. Beral V.. Hill M.J. Nitrate and human cancer: A review of the
evidence. International Journal of Epidemiology. 9:3-11.
Fraser P., Chilvers C. Health aspects of nitrate in drinking water. Science Total Environ.
Hallberg G.T. Nitrates in groundwater in Iowa. Proceedings of Nitrogen and Groundwater
Conferences. Iowa Fertilizer and Chemical Association. Ames. Iowa. 1986.
Health and Environment Network Nitrate: Rerun of an old horror. Health and
Environment Digest. Vol. 1. No. 12. Jan. 1988.
International Agency for Research on Cancer. IARC monographs on the evaluation of the
carcinogenic risk of chemicals to humans. Vol. 17. Some N-Nitroso Compounds. Lyon.
France. 1978f.
International Agency for Research on Cancer. IARC monographs on the evaluation of the
carcinogenic risk of chemicals to humans. Vol. 30. Miscellaneous Pesticides. Lyon, France.
Johnson CJ., Bonrud M.S.. Dosch T.L., Kilness A.W., et. at. Fatal outcome of
methemoglobinemia in an infant Journal of the American MedicalAssociation 257:2796-
Keetcy D., Daniel T.C., Shaw B. Nitrate in Wisconsin Groundwater: Sources and
Concerns, Univetsity of Wisconsin Extension. 1980.
Mancl IKM.. Nitrate in Drinking Water. The Ohio State University. Extension Service
Bulletin 744. 1987.
National Academy of Science. Drinking Water and Health. Vol. 1. National Academy
Press, Washington. DC. 1977.
National Academy of Sciences. Committee on Nitrate and Alternative Curing Agents in
Food. The Health Effects of Nitrate. Nitrite and N-Nitroso Compounds. National Academy
Press. Washington. DC. 1981.
Re'tig B.. Jacobs CA 1985 doemstic well water sampling in central Nebraska: Laboratory
findings, and their implications. Nebraska Department of Health, 1986.
Riddef W.E, Oehme F.W. Nitrates as an environmental, animal, and human hazard.
Clinical lxicology 7:145-159.
Shuval H.I.. Gruener N. Epidemiological and toxicological aspects of nitrates and nitrites
in the environment. American Journal of Public Health 62:1045-1052.
Sollmann T. Manual of Pharmacology. 5th Edition. W.B. Saunders Publishers, Pgs. 166,
167, 142. 1936. I

Written by:
Deborah Plumb, Health Consultant
Muriel Morrisette. Freshwater Foundation

Assistance provided by:
Jim Anderson, Ph.D.
University of Minnesota CenterforAgricultural Impacts on Water Quality
Buddy Ferguson
Minnesota Department of Health
Larry Gust
Minnesota Department of Health
George Hallberg, Ph.D.
Geological Survey Bureau, Iowa Department of Natural Resources
Carl Johnson, M.D.
South Dakota Department of Health
Tom Klaseus
Minnesota Department of Health
Carolyn McKay, M.D.
Minnesota Department of Health
Barbara Scott Murdock
Health and Environment Digest
Leonard Schuman, M.D.
University of Minnesota
Rex Singer
University of Minnesota
Raymond W. Thron, Ph.D.
Minnesota Department of Health
John Wood, Ph.D.
Gray Freshwater Biological Institute

For additional copies of this brochure or other related publications,
contact the Freshwater Foundation. For information on membership in
the Freshwater Foundation, call or write:
Freshwater Foundation
2500 Shadywood Road, Box 90
Navarre, Minnesota 55392
(612) 471-8407

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