Drinking Water Nitrate and Health – Recent Findings and Research Needs

Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA.
Environmental Health Perspectives (Impact Factor: 7.98). 12/2005; 113(11):1607-14. DOI: 10.1289/ehp.8043
Source: PubMed


Human alteration of the nitrogen cycle has resulted in steadily accumulating nitrate in our water resources. The U.S. maximum contaminant level and World Health Organization guidelines for nitrate in drinking water were promulgated to protect infants from developing methemoglobinemia, an acute condition. Some scientists have recently suggested that the regulatory limit for nitrate is overly conservative; however, they have not thoroughly considered chronic health outcomes. In August 2004, a symposium on drinking-water nitrate and health was held at the International Society for Environmental Epidemiology meeting to evaluate nitrate exposures and associated health effects in relation to the current regulatory limit. The contribution of drinking-water nitrate toward endogenous formation of N-nitroso compounds was evaluated with a focus toward identifying subpopulations with increased rates of nitrosation. Adverse health effects may be the result of a complex interaction of the amount of nitrate ingested, the concomitant ingestion of nitrosation cofactors and precursors, and specific medical conditions that increase nitrosation. Workshop participants concluded that more experimental studies are needed and that a particularly fruitful approach may be to conduct epidemiologic studies among susceptible subgroups with increased endogenous nitrosation. The few epidemiologic studies that have evaluated intake of nitrosation precursors and/or nitrosation inhibitors have observed elevated risks for colon cancer and neural tube defects associated with drinking-water nitrate concentrations below the regulatory limit. The role of drinking-water nitrate exposure as a risk factor for specific cancers, reproductive outcomes, and other chronic health effects must be studied more thoroughly before changes to the regulatory level for nitrate in drinking water can be considered.

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    • "Pollution of drinking water with nitrate presents a serious health hazard because at concentrations higher than 10 mg N/L, nitrite formed may lead to methemoglobinemia or blue baby syndrome in infants and gastrointestinal cancer in adults (Fonseca et al., 2000; Ward et al., 2005). Groundwater polluted by nitrates typically contains almost no organic matter, thus sulfur-based autotrophic denitrification as illustrated in Eq. (1) has been reported to be an alternative for the removal of nitrate in contaminated drinking water (Sierra-Alvarez et al., 2007; Sahinkaya et al., 2011; Sahinkaya and Kilic, 2014). "
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    ABSTRACT: Sulfur-based mixotrophic denitrifying anoxic fluidized bed membrane bioreactors (AnFB-MBR) were developed for the treatment of nitrate-contaminated groundwater with minimized sulfate production. The nitrate removal rates obtained in the methanol- and ethanol-fed mixotrophic denitrifying AnFB-MBRs reached 1.44-3.84 g [Formula: see text] -N/Lreactor d at a hydraulic retention time of 0.5 h, which were significantly superior to those reported in packed bed reactors. Compared to methanol, ethanol was found to be a more effective external carbon source for sulfur-based mixotrophic denitrification due to lower sulfate and total organic carbon concentrations in the effluent. Using pyrosequencing, the phylotypes of primary microbial groups in the reactor, including sulfur-oxidizing autotrophic denitrifiers, methanol- or ethanol-supported heterotrophic denitrifiers, were investigated in response to changes in electron donors. Principal component and heatmap analyses indicated that selection of electron donating substrates largely determined the microbial community structure. The abundance of Thiobacillus decreased from 45.1% in the sulfur-oxidizing autotrophic denitrifying reactor to 12.0% and 14.2% in sulfur-based methanol- and ethanol-fed mixotrophic denitrifying bioreactors, respectively. Heterotrophic Methyloversatilis and Thauera bacteria became more dominant in the mixotrophic denitrifying bioreactors, which were possibly responsible for the observed methanol- and ethanol-associated denitrification.
    Water Research 09/2015; 85:422-431. DOI:10.1016/j.watres.2015.08.055 · 5.53 Impact Factor
    • "Higher concentrations of NO 3 –N in groundwater are typically caused by anthropogenic activities including nitrogen compounds from synthetic fertilizers or manure used in agriculture, septic systems and other waste waters (McLay et al., 2001). In drinking water, concentration of NO 3 –N in excess of 10 mg L −1 may result in blue baby syndrome in infants (methemoglobinemia ) and may be a contributing factor for some types of cancer (Ward et al., 2005). In many agricultural regions, groundwater is often the major source of water both for drinking water and irrigation purposes. "
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    ABSTRACT: An integrated study based on hydrogeochemical, microbiological and dual isotopic approaches for nitrate and sulfate was conducted to elucidate sources and biogeochemical reactions governing groundwater contaminants in different seasons and under different land use in a basin of Korea. The land use in the study area is comprised of forests (58.0%), vegetable fields (27.6%), rice paddy fields (11.4%) and others (3.0%). The concentrations of NO3-N and SO4(2-) in groundwater in vegetable fields were highest with 4.2-15.2mgL(-1) and 1.6-19.7mgL(-1) respectively, whereas under paddy fields NO3-N concentrations ranged from 0 to 10.7mgL(-1) and sulfate concentrations were ~15mgL(-1). Groundwater with high NO3-N concentrations of >10mgL(-1) had δ(15)N-NO3(-) values ranging from 5.2 to 5.9‰ and δ(18)O values of nitrate between 2.7 and 4.6‰ suggesting that the nitrate was mineralized from soil organic matter that was amended by fertilizer additions. Elevated concentrations of SO4(2-) with δ(34)S-SO4(2-) values between 1 and 6‰ in aquifers in vegetable fields indicated that a mixture of sulfate from atmospheric deposition, mineralization of soil organic matter and from synthetic fertilizers is the source of groundwater sulfate. Elevated δ(18)O-NO3(-) and δ(18)O-SO4(2-) values in samples collected from the paddy fields indicated that denitrification and bacterial sulfate reduction are actively occurring removing sulfate and nitrate from the groundwater. This was supported by high occurrences of denitrifying and sulfate reducing bacteria in groundwater of the paddy fields as evidenced by 16S rRNA pyrosequencing analysis. This study shows that dual isotope techniques combined with microbial data can be a powerful tool for identification of sources and microbial processes affecting NO3(-) and SO4(2-) in groundwater in areas with intensive agricultural land use. Copyright © 2015 Elsevier B.V. All rights reserved.
    Science of The Total Environment 07/2015; 533:566-575. DOI:10.1016/j.scitotenv.2015.06.080 · 4.10 Impact Factor
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    • "The main factors are the demographic explosion with development of anthropogenic activities resulting in increases of waste volumes, deforestation for agricultural lands, increases of fertilizer use, intensification of animal production . . . . Scientists have pointed out the effect of such uncontrolled development on human health since 1945 regarding high concentration of nitrate in drinking water (Comly, 1945; Fewtrell, 2004; Greer and Shannon, 2005) and others pathologies like cancers and reproductive outcomes (Ward et al., 2005) or on the sustainability of ecosystems since the beginning of the 1970s (Ryther and Dunstan, 1971). Concerning factors affecting the export of nitrogen a lot of works have been published during the last decade (Drewry et al., 2006; Pellerin et al., 2006; Schindler et al., 2006; Alvarez-Cobelas et al., 2008; Howarth, 2008; Sutton et al., 2011; Pärn et al., 2012). "
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    ABSTRACT: In spite of several studies on factors affecting nitrogen (N) export in water, the spatio-temporal variability of N export is rarely addressed. This review aims at discussing the different factors involved in N export in water and the intra-annual variability of N occurrences in rivers at a watershed scale. From the analysis of the existing works some recommendations on future research work are proposed regarding i) other N forms than nitrate being systematically considered for routine analysis or experimental studies (at least Kjheldal nitrogen), ii) hydrologists and biogeochemists working together to better understanding of N dynamics according to water pathways, especially during “situations at risk”, iii) water quality monitoring being reinforced both spatially and temporally, especially thanks to high frequency instrumentation and iv) accurate data on watersheds needed to give better explanations of N variations. We argue that a better understanding of spatio-temporal variability could greatly enhance the remediation of N export impacts, which is crucial to anticipate the impacts of global changes.
    Critical Reviews in Environmental Science and Technology 02/2015; 45(20):00-00. DOI:10.1080/10643389.2015.1010432 · 3.47 Impact Factor
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