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Nitrate in public water supplies and the risk of colon and rectum cancers.
Epidemiology. 2003 Nov; 14(6):640-9.E

Abstract

BACKGROUND

Nitrate is a widespread contaminant of drinking water, but its potential health effects are unclear. In the body, nitrate is reduced to nitrite, which can react with amines and amides by nitrosation to form N-nitroso compounds, known animal carcinogens. N-nitroso compound formation is inhibited by certain nutrients, such as vitamin C, and increased by meat intake.

METHODS

We investigated the association of nitrate in public water supplies with incident colon and rectum cancers in a case-control study conducted in Iowa from 1986 to 1989. Nitrate levels in Iowa towns were linked to the participants' water source histories. We focused our analyses on the period from 1960 onward, during which nitrate measurements were more frequent, and we restricted analyses to those persons with public water supplies that had nitrate data (actual or imputed) for greater than 70% of this time period (376 colon cancer cases, 338 rectum cancer cases, and 1244 controls).

RESULTS

There were negligible overall associations of colon or rectum cancers with measures of nitrate in public water supplies, including average nitrate and the number of years with elevated average nitrate levels. For more than 10 years with average nitrate greater than 5 mg/L, the odds ratio (OR) for colon cancer was 1.2 (95% confidence interval [CI] = 0.9-1.6) and for rectum the OR was 1.1 (CI = 0.7-1.5). However, nitrate exposure (>10 years with average nitrate >5 mg/L) was associated with increased colon cancer risk among subgroups with low vitamin C intake (OR = 2.0; CI = 1.2-3.3) and high meat intake (OR = 2.2; CI = 1.4-3.6). These patterns were not observed for rectum cancer.

CONCLUSIONS

Our analyses suggest that any increased risk of colon cancer associated with nitrate in public water supplies might occur only among susceptible subpopulations.

Authors+Show Affiliations

Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, USA. aderoos@fhcrc.orgNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

14569178

Citation

De Roos, Anneclaire J., et al. "Nitrate in Public Water Supplies and the Risk of Colon and Rectum Cancers." Epidemiology (Cambridge, Mass.), vol. 14, no. 6, 2003, pp. 640-9.
De Roos AJ, Ward MH, Lynch CF, et al. Nitrate in public water supplies and the risk of colon and rectum cancers. Epidemiology. 2003;14(6):640-9.
De Roos, A. J., Ward, M. H., Lynch, C. F., & Cantor, K. P. (2003). Nitrate in public water supplies and the risk of colon and rectum cancers. Epidemiology (Cambridge, Mass.), 14(6), 640-9.
De Roos AJ, et al. Nitrate in Public Water Supplies and the Risk of Colon and Rectum Cancers. Epidemiology. 2003;14(6):640-9. PubMed PMID: 14569178.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Nitrate in public water supplies and the risk of colon and rectum cancers. AU - De Roos,Anneclaire J, AU - Ward,Mary H, AU - Lynch,Charles F, AU - Cantor,Kenneth P, PY - 2003/10/22/pubmed PY - 2004/2/5/medline PY - 2003/10/22/entrez SP - 640 EP - 9 JF - Epidemiology (Cambridge, Mass.) JO - Epidemiology VL - 14 IS - 6 N2 - BACKGROUND: Nitrate is a widespread contaminant of drinking water, but its potential health effects are unclear. In the body, nitrate is reduced to nitrite, which can react with amines and amides by nitrosation to form N-nitroso compounds, known animal carcinogens. N-nitroso compound formation is inhibited by certain nutrients, such as vitamin C, and increased by meat intake. METHODS: We investigated the association of nitrate in public water supplies with incident colon and rectum cancers in a case-control study conducted in Iowa from 1986 to 1989. Nitrate levels in Iowa towns were linked to the participants' water source histories. We focused our analyses on the period from 1960 onward, during which nitrate measurements were more frequent, and we restricted analyses to those persons with public water supplies that had nitrate data (actual or imputed) for greater than 70% of this time period (376 colon cancer cases, 338 rectum cancer cases, and 1244 controls). RESULTS: There were negligible overall associations of colon or rectum cancers with measures of nitrate in public water supplies, including average nitrate and the number of years with elevated average nitrate levels. For more than 10 years with average nitrate greater than 5 mg/L, the odds ratio (OR) for colon cancer was 1.2 (95% confidence interval [CI] = 0.9-1.6) and for rectum the OR was 1.1 (CI = 0.7-1.5). However, nitrate exposure (>10 years with average nitrate >5 mg/L) was associated with increased colon cancer risk among subgroups with low vitamin C intake (OR = 2.0; CI = 1.2-3.3) and high meat intake (OR = 2.2; CI = 1.4-3.6). These patterns were not observed for rectum cancer. CONCLUSIONS: Our analyses suggest that any increased risk of colon cancer associated with nitrate in public water supplies might occur only among susceptible subpopulations. SN - 1044-3983 UR - https://www.unboundmedicine.com/medline/citation/14569178/Nitrate_in_public_water_supplies_and_the_risk_of_colon_and_rectum_cancers_ L2 - http://dx.doi.org/10.1097/01.ede.0000091605.01334.d3 DB - PRIME DP - Unbound Medicine ER -