Journal article
Nitrate exposure from drinking water and dietary sources among Iowa farmers using private wells
The Science of the total environment, Vol.919, pp.170922-170922
04/01/2024
DOI: 10.1016/j.scitotenv.2024.170922
PMCID: PMC11665930
PMID: 38350573
Abstract
Nitrate levels are increasing in water resources across the United States and nitrate ingestion from drinking water has been associated with adverse health risks in epidemiologic studies at levels below the maximum contaminant level (MCL). In contrast, dietary nitrate ingestion has generally been associated with beneficial health effects. Few studies have characterized the contribution of both drinking water and dietary sources to nitrate exposure. The Agricultural Health Study is a prospective cohort of farmers and their spouses in Iowa and North Carolina. In 2018–2019, we assessed nitrate exposure for 47 farmers who used private wells for their drinking water and lived in 8 eastern Iowa counties where groundwater is vulnerable to nitrate contamination. Drinking water and dietary intakes were estimated using the National Cancer Institute Automated Self-Administered 24-Hour Dietary Assessment tool. We measured nitrate in tap water and estimated dietary nitrate from a database of food concentrations. Urinary nitrate was measured in first morning void samples in 2018–19 and in archived samples from 2010 to 2017 (minimum time between samples: 2 years; median: 7 years). We used linear regression to evaluate urinary nitrate concentrations in relation to total nitrate, and drinking water and dietary intakes separately. Overall, dietary nitrate contributed the most to total intake (median: 97 %; interquartile range [IQR]: 57–99 %). Among 15 participants (32 %) whose drinking water nitrate concentrations were at/above the U.S. Environmental Protection Agency MCL (10 mg/L NO3-N), median intake from water was 44 % (IQR: 26–72 %). Total nitrate intake was the strongest predictor of urinary nitrate concentrations (R2 = 0.53). Drinking water explained a similar proportion of the variation in nitrate excretion (R2 = 0.52) as diet (R2 = 0.47). Our findings demonstrate the importance of both dietary and drinking water intakes as determinants of nitrate excretion.
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•Few studies of nitrate excretion evaluated exposures among users of unregulated private wells.•Water and dietary intakes were independent predictors of nitrate excretion.•Water and dietary nitrate intakes explained a similar amount of variation in excretion.•At levels at/above regulatory limit, water was a major contributor to exposure.
Details
- Title: Subtitle
- Nitrate exposure from drinking water and dietary sources among Iowa farmers using private wells
- Creators
- Timothy G. Skalaban - National Cancer InstituteDarrin A. Thompson - University of IowaJessica M. Madrigal - National Cancer InstituteBenjamin C. Blount - National Center for Environmental HealthMaria Morel Espinosa - National Center for Environmental HealthDana W. Kolpin - United States Geological SurveyNicole C. Deziel - Yale UniversityRena R. Jones - National Cancer InstituteLaura Beane Freeman - National Cancer InstituteJonathan N. Hofmann - National Cancer InstituteMary H. Ward - National Cancer Institute
- Resource Type
- Journal article
- Publication Details
- The Science of the total environment, Vol.919, pp.170922-170922
- DOI
- 10.1016/j.scitotenv.2024.170922
- PMID
- 38350573
- PMCID
- PMC11665930
- NLM abbreviation
- Sci Total Environ
- ISSN
- 0048-9697
- eISSN
- 1879-1026
- Publisher
- Elsevier B.V
- Language
- English
- Date published
- 04/01/2024
- Academic Unit
- Center for Health Effects of Environmental Contamination; Occupational and Environmental Health
- Record Identifier
- 9984622056202771
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