Abstract 2299: Toxic metals in private well water and bladder and kidney cancer incidence in North Carolina
Authors: Shrestha Deepika , Cronkrite Selin , Sanders Alison , Fry Rebecca , Applebaum Katie M. 
Published: July 2017

Introduction: There are a limited number of studies conducted in the US that have related metals in well water with kidney and bladder cancer. We investigated levels of arsenic (As), cadmium (Cd), manganese (Mn), and lead (Pb) in private well water and the association with incidence of bladder and kidney cancer in 100 counties in North Carolina, a state that has among the highest proportion of well water consumers in the country.

Methods: Between 1998-2010, private wells across 100 NC counties were analyzed for levels of As, Cd, Mn and Pb (n=63,836, n=22,915, n=70,675 and n=65,535 measurements, respectively) and geocoded. Bladder and kidney cancer incidence for each county between 1990 and 2011 were obtained from the North Carolina Department of Health and Human Services. County-level data on potential confounders were obtained from US Census Bureau data (2010) and the Behavioral risk factor surveillance study (2003, 2005). For each county, the mean concentration of each metal and the incidence rate of kidney and bladder cancer were calculated separately. Using counties as the unit of analysis, we used Poisson regression to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) between mean concentration of the four metals and kidney and bladder cancer incidence, adjusting for age, gender, race, education, physical activity, smoking, diabetes, hypertension and residential well water supply. County mean metal levels were analyzed in tertiles. Counties with less than 10 cases or fewer than 10 well measurements for any metal were excluded from the analysis.

Results: Ninety-eight counties were included in the final analysis. In the fully adjusted model, elevated IRRs for kidney cancer were observed in counties with the highest tertile of As (3rd tertile: 0.99-11.44 ppb, IRR=1.05 (95% CI 1.00, 1.11)). Similarly, elevated IRRs for kidney cancer were observed for both the 2nd and 3rd tertiles of Cd (3rd tertile 0.61-2.98 ppb: IRR=1.05 (95% CI 1.00, 1.10)) and the 2nd tertile of Pb (3.88-5.05 ppb, IRR=1.05 (95% CI 1.00, 1.10)). A dose response was observed for kidney cancer incidence and Mn (2nd tertile: 37.33-51.74 pbb; IRR =1.06 (95% CI 1.02, 1.11); 3rd tertile: 52.95-146.60 ppb: IRR=1.13 (95% CI 1.08, 1.19)). For bladder cancer, no relationship was observed with As but IRRs were elevated for the other metals including potential dose-response trend with Cd and Mn (Pb 2nd tertile 3.88-5.05 ppb: IRR=1.03 (95% CI 1.00, 1.07); Cd 3rd tertile 0.61-2.98 ppb: IRR=1.10 (95% CI 1.06, 1.15); Mn 3rd tertile 52.95-146.60 ppb: IRR=1.12 (95% CI 1.08, 1.16)).

Conclusion: In North Carolina, counties with higher mean private well metal levels had elevated kidney and bladder cancer incidence rates. The conclusions are limited by the ecological approach, but the consistency of the associations suggests that the influence of metals in private well water in North Carolina on health outcome deserves additional investigation.

Citation Format: Deepika Shrestha, Selin Cronkrite, Alison Sanders, Rebecca Fry, Katie M. Applebaum. Toxic metals in private well water and bladder and kidney cancer incidence in North Carolina [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2299. doi:10.1158/1538-7445.AM2017-2299