Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2010 May;21(3):389-95.
doi: 10.1097/EDE.0b013e3181d6201d.

Nitrate intake and the risk of thyroid cancer and thyroid disease

Mary H Ward  1 , Briseis A Kilfoy, Peter J Weyer, Kristin E Anderson, Aaron R Folsom, James R Cerhan
Affiliations

Nitrate intake and the risk of thyroid cancer and thyroid disease

Mary H Ward et al. Epidemiology. 2010 May.

Abstract

Background: Nitrate is a contaminant of drinking water in agricultural areas and is found at high levels in some vegetables. Nitrate competes with uptake of iodide by the thyroid, thus potentially affecting thyroid function.

Methods: We investigated the association of nitrate intake from public water supplies and diet with the risk of thyroid cancer and self-reported hypothyroidism and hyperthyroidism in a cohort of 21,977 older women in Iowa who were enrolled in 1986 and who had used the same water supply for >10 years. We estimated nitrate ingestion from drinking water using a public database of nitrate measurements (1955-1988). Dietary nitrate intake was estimated using a food frequency questionnaire and levels from the published literature. Cancer incidence was determined through 2004.

Results: We found an increased risk of thyroid cancer with higher average nitrate levels in public water supplies and with longer consumption of water exceeding 5 mg/L nitrate-N (for >or=5 years at >5 mg/L, relative risk [RR] = 2.6 [95% confidence interval (CI) = 1.1-6.2]). We observed no association with prevalence of hypothyroidism or hyperthyroidism. Increasing intake of dietary nitrate was associated with an increased risk of thyroid cancer (highest vs. lowest quartile, RR = 2.9 [1.0-8.1]; P for trend = 0.046) and with the prevalence of hypothyroidism (odds ratio = 1.2 [95% CI = 1.1-1.4]), but not hyperthyroidism.

Conclusions: Nitrate may play a role in the etiology of thyroid cancer and warrants further study.

PubMed Disclaimer

References

    1. Ron E, Schneider A. Thyroid cancer. In: Schottenfeld D, Fraumeni JF Jr, editors. Cancer Epidemiology and Prevention. 3. New York: Oxford University Press; 2006. pp. 975–994.
    1. Ries LAG, Melbert D, Krapcho M, et al. SEER Cancer Statistics Review: 1975–2004. Bethesda, MD: National Cancer Institute; 2004.
    1. Davies L, Welch HG. Increasing incidence of thyroid cancer in the United States, 1973–2002. JAMA. 2006;295:2164–2167. - PubMed
    1. Enewold L, Zhu K, Ron E, et al. Rising thyroid cancer incidence in the United States by demographic and tumor characteristics, 1980–2005. Cancer Epidemiol Biomarkers Prev. 2009;18:784–791. - PMC - PubMed
    1. Kilfoy BA, Devesa SS, Ward MH, et al. Gender is an age-specific effect modifier for papillary cancers of the thyroid gland. Cancer Epidemiol Biomarkers Prev. 2009;18:1092–1100. - PMC - PubMed

Publication types