Background: The association between trace elements and bladder cancer risk is not well understood. Individuals are typically exposed to a mixture of multiple elements simultaneously, such as through water pollution or diet. While previous studies have explored associations between individual elements and bladder cancer, there has been limited work in exploring the overall or joint effect of these elements. Methods: We leveraged the New England Bladder Cancer Study, a population-based matched case-control study, to estimate associations between a mixture of 12 trace elements and bladder cancer. Toenail clipping samples were collected and analyzed for 12 trace elements from 979 cases and 1232 controls. Using quantile-based g-computation, we assessed associations between the overall elements mixture and bladder cancer risk. Results: After adjustment for matching factors (i.e., age, sex, and state) and other potential confounders (e.g., smoking habits and high-risk occupation), we estimated an inverse association between the overall mixture of trace elements and bladder cancer (odds ratio: 0.78, 95% confidence interval: 0.66, 0.93). Results were relatively unchanged after adjustment for smoking, high-risk occupation, and diet. We examined indirect evidence for reverse causation in explaining this inverse relationship for arsenic and found evidence that bladder cancer diagnosis may lead to changes in short-term behavior, which affects concentrations of arsenic and possibly other elements in toenail samples.
Maria E. Kamenetsky, Stella Koutros, Maya Spaur et al.· Environmental Epidemiology· 0 citations
In the U.S., drinking water is an important source of exposure to inorganic arsenic, an established human carcinogen. Chronic exposure to low levels of inorganic arsenic (≤10 μg/L) has been linked to bladder and kidney cancers; however, the association with other cancers remains inconsistent. We investigated the association between arsenic from private wells and community water systems and breast cancer incidence in a large U.S.-wide prospective cohort. Among 33,864 Sister Study participants residing in states with available arsenic data and reporting eligible water source types at enrollment (2003-2009), geocoded residential addresses were linked to county-level water arsenic concentrations. For community water system (CWS) users (n=27,290), addresses were linked to county-level water arsenic concentrations using the EPA National Contaminant Occurrence database (2006-2008). For well water users (n =6,574), addresses were linked to county-level modeled probabilities that arsenic levels in private well water exceeded 10 μg/L. Cox proportional hazards regression was used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for the association between water arsenic and incident breast cancer, with subgroup analyses by tumor subtypes and menopausal status. Over 13.2 years (mean) of follow-up, 3,309 breast cancer cases (invasive and ductal carcinoma in situ) were diagnosed. We observed non-monotonic but elevated associations between increasing levels of water arsenic and invasive breast cancer risk (CWS HRQ5vsQ1=1.11, 95%CI 0.98-1.27, P-trend=0.16; Well HRQ5vsQ1=1.11, 95%CI 0.84-1.47, P-trend=0.88). When stratified by hormone receptor status and menopausal status, the associations did not meaningfully differ between subgroups. In a nationwide prospective cohort, we observed a suggestive positive association between relatively higher water arsenic levels and breast cancer incidence; however, the non-monotonic trends and exposure assessment limitations warrant further investigation. These results suggest that levels of arsenic in water in the U.S. may contribute to breast cancer risk.
Katherine Pullella, Maya Spaur, Jennifer L. Ish et al.· Environmental Pollution· 0 citations
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