Work

Water arsenic levels and breast cancer risk in a United States-wide prospective cohort

Year: 2026

Type: article

Abstract: 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 HR Q5vsQ1 =1.11, 95%CI 0.98–1.27, P-trend=0.16; Well HR Q5vsQ1 =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.

Source: Environmental Pollution

DOI: 10.1016/j.envpol.2026.128984

Authors: Katherine Pullella, Maya Spaur, Jennifer L. Ish, Rena R. Jones, Dale P. Sandler, Alexandra J. White

Institutions: National Institute of Environmental Health Sciences, National Cancer Institute

Language: English

Topic: Arsenic contamination and mitigation

Subfield: Environmental Chemistry

Field: Environmental Science

Domain: Physical Sciences

SDGs: Good health and well-being, Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $4,090