Relationship between low-level arsenic exposure in drinking water and kidney cancer risk in Texas

Kidney cancer rates are increasing in the US and worldwide. Arsenic, a known human carcinogen, is a suspected contributor to this rise, particularly in areas with arsenic-rich groundwater. However, research on the connection between low-level arsenic in drinking water and kidney cancer is limited. In our ecological study, we assessed the association between county-level drinking water arsenic levels and kidney cancer incidences using data from 240 counties in Texas. The analysis included 28,896 cancer cases among adults aged >= 20 years and 101,776,294 person-years during the period 2016-2020. Spatial Poisson regression models estimated the risk ratio (RR) for incident kidney cancer based on drinking water arsenic levels, adjusting for demographic, socioeconomic, and other risk factors, as well as spatial factors. Population-weighted drinking water arsenic levels were calculated using data from water testing for both public water systems and private wells, adjusted for populations served from each source. After adjusting for spatial factors and covariates, we observed 6% and 22% higher incidence of cancer in the medium (1-5 ppb) (RR 1.06, 95% CI 1.01, 1.11) and high arsenic (>5 ppb) group counties (RR 1.22, 95% CI 1.12, 1.34) compared to the low arsenic level ones (<1 ppb), showing a dose-response relationship (p-trend <0.001). Additionally, when arsenic was treated as a continuous variable, the incidence increased by 4% for each doubling of drinking water arsenic level (RR 1.04, 95% CI 1.02, 1.07) when considering drinking water arsenic level as a continuous variable. Our study suggests that exposure to low-level drinking water arsenic may be associated with an increased risk of kidney cancer. Further prospective studies are required to confirm our findings.