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Health Indicator Report of Community Water: Nitrate Concentration

Nitrate toxicity is a preventable cause of methemoglobinemia (blue baby syndrome), especially in infants. Infants younger than 4 months of age are at greatest risk of toxicity from nitrate-contaminated drinking water. These infants are more susceptible to developing methemoglobinemia because the pH of their gut is normally higher (less acidic) than in older children and adults. The higher pH enhances the conversion of ingested nitrate to the more toxic nitrite. The bacterial flora of a young infant's gut is also different from that found in older children and adults and might be more likely to convert ingested nitrate to nitrite. Gastroenteritis can increase body transformation of nitrate to nitrite and absorption into the bloodstream of nitrite from the large intestine. A large proportion of hemoglobin in young infants is in the form of fetal hemoglobin. Fetal hemoglobin is more readily oxidized to methemoglobin (MHg) by nitrites than is adult hemoglobin. In addition, in infants, the enzyme (NADH-dependent methemoglobin reductase) responsible for reduction of formed MHg back to normal hemoglobin has only about half the activity it has in adults. Symptoms such as shortness of breath and bluish skin coloring around the mouth, hands, or feet, can occur in infants rapidly over a period of days. If the condition is severe, it could lead to convulsions, coma, and even death, if untreated. Most older children and adults can take in larger amounts of nitrate without experiencing the same health effects as infants. However, pregnant women, nursing mothers, and people with low stomach acid conditions or those deficient in an enzyme that changes MHg back to normal hemoglobin are more susceptible to nitrate-induced methemoglobinemia and could be affected by water with nitrate levels above 10 mg/L. Adverse reproductive outcomes such as spontaneous abortions, intrauterine growth retardation, and various birth defects such as anencephaly have been reported in scientific literature from exposure to high nitrate levels in drinking water; however, the evidence is inconsistent. Little is known about possible health effects from high nitrate level exposure over a long period of time. However, some studies suggest that there might be a risk of stomach, esophageal or bladder cancers in people with prolonged ingestion of high levels of nitrate. This might be due to the formation of nitrosoamines in the body following ingestion exposure to high levels of nitrate. International Agency for Research on Cancer (IARC) classified ingested nitrate or nitrite as probably carcinogenic to humans (Group 2A) under conditions that result in formation of nitroso-compounds (e.g., nitrosoamines) in the body (endogenous nitrosation). People who use their private wells water for drinking are solely responsible for testing the water for nitrate (for information about laboratories certified to test drinking water and certified home treatment units visit https://nmtracking.org/environment/water/PrivateWells.html).

Notes

Data Source: New Mexico Environment Department Drinking Water Bureau, New Mexico Safe Drinking Water Information System (SDWIS). Measured nitrate concentrations in finished drinking can be used to understand the distribution of potential nitrate exposure level for populations served by community water supplies. Due to potential errors in estimating service population, the measures may overestimate or underestimate the number of potentially affected people. In addition, the older data (i.e., 1999 through 2004) may be of poor quality that could result in over- or underestimated nitrate concentration in CWS drinking water during 1999-2004. These measures allow for comparison of potential nitrate exposure between the populations served by different water systems over time.   Note: Values have been carried forward from 1999 when new values are not available.

Data Source

New Mexico Environment Department, Drinking Water Bureau

Data Interpretation Issues

Measures do not account for the variability in sampling, number or sampling repeats, etc. Furthermore, concentrations in drinking water cannot be directly converted to exposure because water consumption varies by climate, level of physical activity, and between people. Due to potential errors in estimating service population, the measures may overestimate or underestimate the number of potentially affected people. In addition, the older data (i.e., 1999 through 2004) may be of poor quality that could result in over- or underestimated nitrate concentration in CWS drinking water during 1999-2004.

Definition

Nitrate concentrations (in milligrams of nitrate-nitrogen per liter of water or mg/L) in community water systems (CWS) are used in conjunction with information about each CWS (such as service population) to generate the following measures shown in this report: 1) statewide nitrate concentration distribution in CWSs by mean and maximum over time, 2) annual distribution of mean and maximum nitrate concentration for persons served by CWS and 3) annual distribution of mean and maximum nitrate concentration by CWS. EPHT data queries -- https://nmtracking.org/dataportal/query/selection/water/WaterSelection.html -- provide detailed results by year for 1) mean nitrate concentration by CWS for a select year, 2) maximum nitrate concentration by CWS for a select year, 3) mean nitrate concentration and the number of CWS by year, 4) maximum nitrate concentration and the number of CWS by year, 5) mean nitrate concentration and the number of persons served by year, 6) maximum nitrate concentration and the number of persons served by year, 7) quarterly distribution of number of CWS by mean nitrate concentration or 8) quarterly distribution by number of people served by mean nitrate concentration. Additionally, users may query the number of persons served and the number of CWS in the state for a select year. A CWS is a public water system (PWS) that serves year-round residents of a community, subdivision, or mobile home park that has at least 15 service connections or an average of at least 25 residents. These CWSs are a subset of all New Mexico PWSs. To measure radium concentration in CWS, drinking water samples are usually taken at entry points to the distribution system or representative sampling points after water treatment has occurred.

Numerator

Concentration of nitrate.

Denominator

Not applicable.

Page Content Updated On 04/17/2018, Published on 04/18/2019
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Content updated: Thu, 18 Apr 2019 07:49:08 MDT