NITRITE (as N)
Update: March 1996
Current Massachusetts Regulatory Limit
MMCL = 1 mg/L (56 FR 3526: 1-30-91). ORS has adopted the MCL promulgated by the U.S. EPA.
Federal Regulatory Limit
Final. The MCL for nitrite is equal to the MCLG of 1 mg/L.
Basis for Criteria
Infants and small children are most susceptible to the effects of nitrate and nitrite. The MCLG is protective of infants and small children. The MCLG was derived based on the RfD developed for nitrate presented below and assumes that a 4 kg infant ingests 0.64 L of formula per day. Because the toxicity database for nitrite is much smaller than the toxicity database for nitrate and due to the demonstrated direct toxicity of this chemical, U.S. EPA is applying an uncertainty factor of 10 to derive an MCLG for nitrite of 1 mg/L (54 FR 22062).
RfD(for nitrate) : 1.6 mg/kg/day
UF: 1 MF: 1
Chronic toxicity, developmental and reproductive toxicity were considered.
Methemoglobinemia in infants.
Nitrate in the human body is reduced to nitrite. Nitrite binds to hemoglobin and is responsible for the formation of methemoglobin which decreases the oxygen carrying capacity of the blood.
The RfD is based on information described by Walton (1951) from a survey conducted by the American Public Health Association (APHA) to identify clinical cases of infantile methemoglobinemia that were associated with ingestion of nitrate-contaminated water. Of a total of 214 cases of methemoglobinemia for which data were available on nitrate levels in water, none occurred in infants consuming water containing <10 mg nitrate-nitrogen/L (1.6 mg nitrate-nitrogen/kg/day).
Cancer Assessment: U.S. EPA has classified nitrite as a Group D carcinogen based upon inadequate data in animals and humans. A risk assessment is underway for nitrate by the U.S. EPA.
PQL: 0.4 mg/l
U.S. EPA 300 Ion chromatography
U.S. EPA 359.1 Spectrophotometric
PQLs and analytical methods may have been updated since this guidance value was last revised. Updated analytical methods for drinking water and their associated PQLs may be found at http://www.epa.gov/safewater/methods/methods.html.
Other Regulatory Data
Any Health Advisories, Reference Doses (RfDs), cancer assessments or Cancer Potency Factors (CPFs) referenced in this document pertain to the derivation of the current guidance value. Updated information may be obtained from the following sources:
Health Advisories - The U.S. EPA provides guidance for shorter-term exposures for chemicals based on their non-cancer effects. Current health advisories may be more current than those used to derive MCLs and may be found at http://www.epa.gov/waterscience/drinking/standards/dwstandards.pdf.
RfDs, cancer assessments and CPFs - For specific information pertaining to derivation of drinking water criteria, consult the Federal Register notice that announces the availability of the most current guidance for that chemical. In addition, information on other current RfDs and CPFs as well as cancer assessments for specific chemicals may be found in the U.S. EPA Integrated Risk Information System (IRIS) at http://www.epa.gov/iris/. Please note that the information in IRIS may differ from that used in the derivation process as published in the Federal Register notice.
Federal Register. November 13, 1985. Part IV. Environmental Protection Agency. 40 CFR Part 141. National Primary Drinking Water Regulations: Synthetic Organic Chemicals, Inorganic Chemicals and Microorganisms; Proposed Rule. (50 FR 46936).
Federal Register. May 22, 1989. Part II. Environmental Protection Agency. 40 CFR Parts 141, 142, and 143. National Primary and Secondary Drinking Water Regulations; Proposed Rule. (54 FR 22062).
Federal Register. January 30, 1991. Part II. Environmental Protection Agency. 40 CFR Parts 141, 142, and 143. National Primary Drinking Water Regulations; Final Rule. (56 FR 3526).
Walton, G. 1951. Survey of literature relating to infant methemoglobinemia due to nitrate contaminated water. Am. J. Public Health. 41:986-996.