Nitrate (NO3) and Nitrite (NO2) are nitrogen-containing compounds that can be found in water and soils.  The presence of nitrate and nitrite generally indicates contamination from a pasture, manure pile, decomposed vegetation or agricultural fertilizers, or sewage, though it may come from erosion of natural deposits.

Nitrates change to nitrites in the body, which reduces oxygen uptake by the hemoglobin and could result in methaemoglobinaemia (blue baby syndrome), which is potentially fatal in infants.

 

Health Limits - Nitrate:

Maine Maximum Exposure Guideline limit: 10 mg/L
USA Primary Drinking Water Standard limit: 10 mg/L

Health Limits - Nitrite:

Maine Maximum Exposure Guideline limit: 1.0 mg/L
USA Primary Drinking Water Standard limit:  1.0 mg/L

Additional Resources:

Maine Division of Environmental Health, "Nitrate/Nitrite" (webpage)

USA CDC "ToxFAQ for Nitrate and Nitrite" (webpage)

Water Quality Association Fact Sheet: "Nitrate/Nitrite" (2014, 6 pg. .pdf):

MEL Test Methods for Nitrate, Nitrite

Drinking Water – EPA Method 300.0 Rev. 2.1 (SDWA Compliant)
Wastewater –EPA Method 300.0 Rev. 2.1 (NPDES Compliant)
Solids & NPW –SW846 Method 9056A (SW846/RCRA Compliant)

Sample Requirements

Aqueous:

Container: plastic, glass
Volume: 60 mL
Hold Time: 48 HOURS
Preservation: Cold, ≤6ºC

Solids:

Container: plastic, glass
Volume: n/a
Hold Time: 14 days
Preservation: Cold, ≤6ºC