Are Ministry of Environment holding times for nitrate and nitrite tests in drinking water justified?

Abstract

Background: Exposure to nitrate and nitrite in high concentration is associated with various health issues in humans such as methemoglobinemia, gastric and bladder cancers. Surface and ground water is vulnerable to nitrate and nitrite contamination which can have a significant impact to communities that use the water for consumption. Methods: Ion chromatography analysis of nitrate and nitrite degradation over time in well water from Abbotsford-Sumas Aquifer was performed in an analytical chemistry study. Nitrate and nitrite test strips marketed for testing drinking water were also used and results were compared to ion chromatography results. Results: Test strips used were unable to detect the level of nitrate/nitrite in the well water sample drawn from the Abbotsford-Sumas aquifer. Ion chromatography, IC, methods were able to detect measurable amounts of nitrates which resulted from concentrations of 1.17 mg/L NO3 as N to 1.13 mg/L NO3 as N from day 0 to 31 of the sampling date. The concentration decreased 0.04 mg/L NO3 as N over 31 days. Nitrites tested by IC were below the detection limit. Conclusion: In regards to nitrates, the MOE holding times are justified in that the concentrations were statistically different (p = 0.0001) from day 0 to day 31 from the sampling date indicating a change of concentration of the chemical due to time. However, the difference was not of a magnitude that may impact public health practices/policies. Test strips comparisons with EPA IC methods were non-conclusive since test strips were unable to detect measurable amounts of nitrate/nitrites. Future studies of nitrate concentrations with respect to chemical and biological components in water may lead to a greater understanding of its change in the environment and thus its association with other potential health hazards.