Nitrate ingestion from drinking water and dietary sources and risk of brain cancer in the Agricultural Health Study
Year: 2023
Type: conference-abstract
Abstract: BACKGROUND AND AIM: N-nitroso compounds (NOC) formed from ingested nitrate/nitrite cause brain tumors in animals. Nitrate and nitrite intakes from drinking water and diet are associated with brain cancer in limited epidemiologic studies. We evaluated these exposures and brain cancer risk in the Agricultural Health Study (AHS). METHOD: The AHS is a prospective cohort of licensed pesticide applicators and their spouses in Iowa (IA) and North Carolina (NC). Drinking water source was ascertained at enrollment (1993-1997; N=74,919). For users of public water supplies (PWS, 25%), we linked participants’ addresses to monitoring data for nitrate-nitrogen (NO3-N) and computed duration-specific averages. For private well users (71%), we estimated NO3-N using random forest models based on well depth, nitrogen inputs, soil characteristics, and other factors. Among 30,177 participants who completed the NCI Dietary History Questionnaire (1999-2003), we assessed dietary nitrate and nitrite intakes using a database of nitrate/nitrite in foods. Incident brain cancers were assessed from enrollment (drinking water analyses, N=137) or first follow-up (diet analyses, N=61) through 2019 (IA) and 2014 (NC). Adjusted hazard ratios (HRs) and 95%CI were computed using Cox regression for average drinking water nitrate concentrations (quartiles [Q], Q4 split at 90th percentile) and tertiles (T) of dietary intakes. We stratified by median intakes of red meat and vitamin C, factors that increase and decrease NOC, respectively. RESULTS: Nitrate concentrations in private wells exceeded 10mg/L NO3-N (regulatory limit, PWS) for 12% of IA and 1% of NC participants. Drinking water nitrate concentrations 7.1 mg/L NO3-N (90th percentile) were associated with increased risk (HR=1.7, 95% CI=1.0-3.0; p-trend=0.08). We observed some evidence of effect modification by red meat and vitamin C. There were no significant associations with dietary nitrate and nitrite. CONCLUSIONS: Drinking water nitrate concentrations were associated with increased risk of brain cancer, supporting endogenously formed NOC as potential risk factors.
Source: ISEE Conference Abstracts
Authors: Mary H. Ward, Jessica M Madrigal, Rashmi Sinha, Jonathan N Hofmann, Dale Sandler, Laura Beane Freeman, Rena R Jones
Language: English
Subfield: Health, Toxicology and Mutagenesis
Field: Environmental Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4390965312