What Are the Health Effects from Exposure to Nitrates and Nitrites?
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Environmental Research - July 2022
Background: Pollution of water sources, largely from wide-scale agricultural fertilizer
use has resulted in nitrate and nitrite contamination of drinking water.
The effects on human health of raised nitrate and nitrite levels in drinking
water are currently unclear.
Conclusions: We identified an association of nitrate in drinking water with gastric
cancer but with no other cancer site. There is currently a paucity of
robust studies from settings with high levels nitrate pollution in drinking
water. Research into this area will be valuable to ascertain the true
health burden of nitrate contamination of water and the need for public
policies to protect human health.
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GeoHelalth - May 2022
Abstract Nitrate ingested from drinking water has been linked to adverse health
outcomes (e.g., cancer, birth defects) at levels as low as 2 mg/L NO3-N,
far below the regulatory limits of 10 mg/L. In many areas, groundwater
is a common drinking water source and may contain elevated nitrate, but
limited data on the patterns and concentrations are available. Using an
extensive regulatory data set of over 100,000 nitrate drinking water well
samples, we developed new maps of groundwater nitrate concentrations from
76,724 wells in Michigan's Lower Peninsula, USA for the 2006-2015
period. Kriging, a geostatistical method, was used to interpolate concentrations
and quantify probability of exceeding relevant thresholds (>0.4 [common
detection limit], >2 mg/L NO3-N). We summarized this probability in
small watersheds (∼80 km2) to identify correlated
variables using the machine learning method classification and regression
trees (CARTs).
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PLOS One - March 2022
Objective: Food safety and nutrition during pregnancy are important concerns related
to fetal brain development. In the present study, we aimed to explore
the effects of omega-3 polyunsaturated fatty acids (PUFA ω-3)
on exogenous sodium nitrite intervention-induced fetal brain injury in
pregnant rats.
Conclusions: Sodium nitrite exposure during pregnancy could cause brain damage in
fetal rats. PUFA ω-3 might help alleviate brain inflammation,
oxidative stress, and mitochondrial damage, possibly through the NRF1/HMOX1
signaling pathway. In conclusion, appropriately reducing sodium nitrite
exposure and increasing PUFA omega-3 intake during pregnancy may benefit
fetal brain development. These findings could further our understanding
of nutrition and health during pregnancy.
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Environmental HealthPerspectives - May 2021
Background: Nitrate is a widespread groundwater contaminant and a leading cause of
drinking water quality violations in California. Associations between
nitrate exposure and select adverse birth outcomes have been suggested,
but few studies have examined gestational exposures to nitrate and risk
of preterm birth (before 37 wk gestation).
Discussion: The results suggest that nitrate in drinking water is associated with
increased odds of spontaneous preterm birth. Notably, we estimated modestly
increased odds associated with tap water nitrate concentrations of 5 to
<10mg/L<10mg/L (below the federal drinking water standard of 10mg/L10mg/L)
relative to <5mg/L<5mg/L. .
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Archives of Environmental & Occupational Health - November 2020
Background: Nitrate is an inorganic compound that occurs naturally in all surface
and groundwater, although higher concentrations tend to occur only where
fertilizers are used on the land. The regulatory limit for nitrate in
public drinking water supplies was set to protect against infant methemoglobinemia,
but other health effects were not considered. Risk of specific cancers
and congenital disabilities may be increased when the nitrate is ingested,
and nitrate is reduced to nitrite, which can react with amines and amides
by nitrosation to form N-nitroso compounds which are known animal carcinogens.
Conclusion: This study showed that there is an association between the intake of
nitrate from drinking water and a type of cancer in humans. The effective
way of controlling nitrate concentrations in drinking water is the prevention
of contamination (water pollution). Further research work on this topic
is needed.
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Wisconsin Department of Health Services (2019)
Protect yourself and your family by testing your well every year for nitrate
and finding a safe source of water if levels are high.
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Environmental Research - September 2019
Background: Nitrate is a common water contaminant that has been associated with birth
defects, although the evidence is limited. The purpose of this study was
to examine whether maternal consumption of nitrate through drinking water
is associated with an increased risk of congenital anomalies.
Conclusion: The positive associations found between nitrate exposure via drinking
water and congenital abnormalities are largely consistent with some previous
epidemiologic studies. The results of this study should be interpreted
with caution given limitations in our ability to estimate exposures and
the lack information on some risk factors for congenital abnormalities.
Our findings may have serious policy implications given that exposure
levels in our study were well below current EPA standards for nitrate
in drinking water.
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By: Mary H. Ward, Rena R. Jones, et al - May 17, 2018
International Journal of Environmental Research and Public Health
Abstract: Nitrate levels in our water resources have increased in many areas of
the world largely due to applications of inorganic fertilizer and animal
manure in agricultural areas. The regulatory limit for nitrate in public
drinking water supplies was set to protect against infant methemoglobinemia,
but other health effects were not considered.
Keywords: drinking water; nitrate; cancer; adverse reproductive outcomes; methemoglobinemia;
thyroid disease; endogenous nitrosation; N-nitroso compounds
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National Service Center for Environmental Publications (NSCEP) - 2014
- What are Nitrates/Nitrites and how are they used?
- Why are Nitrates/Nitrites being regulated?
- What are the health effects
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Journal of Environmental Quality - February 2008
Abstract Is nitrate harmful to humans? Are the current limits for nitrate concentration
in drinking water justified by science? There is substantial disagreement
among scientists over the interpretation of evidence on the issue. There
are two main health issues: the linkage between nitrate and (i) infant
methaemoglobinaemia, also known as blue baby syndrome, and (ii) cancers
of the digestive tract. The evidence for nitrate as a cause of these serious
diseases remains controversial.
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Teach Chemical Summary
- Last revised May 2007
Nitrates and nitrites are chemicals used in fertilizers, in rodenticides
(to kill rodents), and as food preservatives. Nitrates and nitrites come
in various forms, but when dried are typically a white or crystalline
powder. Nitrate (NO3 - ) and nitrite (NO2 - ) are also naturally-occurring
compounds that are a metabolic product of microbial digestion of wastes
containing nitrogen, for example, animal feces or nitrogen-based fertilizers.
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Environmental Health Perspectives - March 2006
Abstract In this review we present an update on maternal exposure to nitrates in
drinking water in relation to possible adverse reproductive and developmental
effects, and also discuss nitrates in drinking water in the United States.
The current standard for nitrates in drinking water is based on retrospective
studies and approximates a level that protects infants from methemoglobinemia,
but no safety factor is built into the standard. The current standard
applies only to public water systems. Drinking water source was related
to nitrate exposure (i.e., private systems water was more likely than
community system water to have nitrate levels above the maximum contaminant
limit). Animal studies have found adverse reproductive effects resulting
from higher doses of nitrate or nitrite.
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