Reduced Arsenic in Drinking Water Tied to Large Drops in Cancer and Cardiovascular Mortality

Highlight

– A prospective cohort of 10,977 adults in Araihazar, Bangladesh, showed that declines in urinary arsenic between 2000 and 2018 were associated with lower mortality from chronic diseases, cancer, and cardiovascular disease (CVD).

– Each interquartile-range (197 µg/g creatinine) decrease in urinary arsenic was associated with a 22% lower chronic-disease mortality (adjusted hazard ratio [aHR], 0.78; 95% CI, 0.75–0.82); cancer mortality fell by 20% (aHR, 0.80; 95% CI, 0.73–0.87) and CVD mortality by 23% (aHR, 0.77; 95% CI, 0.73–0.81).

– Participants whose urinary arsenic declined from above to below the baseline median had roughly half the chronic-disease mortality seen in those with consistently high exposure.

Background and disease burden

Arsenic contamination of groundwater is a major environmental health problem in many regions worldwide, particularly in parts of South Asia. Chronic ingestion of inorganic arsenic via contaminated drinking water is an established cause of skin, bladder, and lung cancers and has been linked to cardiovascular disease, diabetes, and other adverse outcomes. The global burden is large because many populations depend on shallow groundwater that can contain high arsenic concentrations. Despite decades of observational evidence linking arsenic exposure to disease, there has been limited longitudinal evidence testing whether reductions in exposure translate into measurable decreases in mortality.

Study design

The study by Wu et al. (JAMA, 2025) reports long-term mortality outcomes in a prospective cohort established in Araihazar, Bangladesh. Key design elements:

• Population: 11,746 adults enrolled 2000–2002 from an area with a wide range of well-water arsenic ( <1 to 864 µg/L; mean 102 µg/L), exceeding Bangladesh’s then-standard of 50 µg/L.
• Exposure measurement: Urinary arsenic, adjusted for creatinine, measured up to five times per participant through 2018; urinary arsenic served as the integrated exposure biomarker reflecting recent intake from water and diet.
• Follow-up: Mortality surveillance through 2022. Analyses included 10,977 participants with calculable changes in urinary arsenic.
• Analytic approach: Time-varying Cox proportional hazards models, restricted cubic spline analyses, and propensity score–matched analyses to evaluate associations between changes in urinary arsenic and mortality from chronic diseases, cancer, and cardiovascular causes.
• Comparative groups: Participants categorized by patterns of urinary arsenic change (e.g., consistently high, declined from above to below the baseline median, consistently low).

Key findings

The study’s principal results demonstrate a clear, quantitatively meaningful, and consistent association between reductions in arsenic exposure and lower mortality:

• Population trends: Mean urinary arsenic declined from 283 µg/g creatinine (SD 314) in 2000 to 132 µg/g creatinine (SD 161) in 2018, reflecting successful community mitigation efforts.
• Dose–response findings: For each interquartile-range decrease in urinary arsenic (197 µg/g creatinine), hazard ratios were: chronic-disease mortality aHR 0.78 (95% CI, 0.75–0.82); cancer mortality aHR 0.80 (95% CI, 0.73–0.87); CVD mortality aHR 0.77 (95% CI, 0.73–0.81). These indicate roughly 20–23% lower relative risk per IQR decrease.
• Pattern-based comparisons: Compared with participants with consistently high urinary arsenic (above baseline median 199 µg/g creatinine), participants who fell below the median had substantially lower risk: chronic-disease mortality aHR 0.46 (95% CI, 0.39–0.53); cancer aHR 0.51 (95% CI, 0.35–0.73); CVD aHR 0.43 (95% CI, 0.34–0.53).
• Consistency: Results were similar in propensity score–matched analyses and when examined with time-varying exposure models and restricted cubic splines, which supported a graded association: larger declines associated with larger mortality reductions, and increases in urinary arsenic associated with higher mortality.

Collectively, these findings suggest that reductions in pervasive environmental exposure to inorganic arsenic can yield measurable benefits in population-level mortality from both cancer and cardiovascular causes.

Interpretation and biological plausibility

The observed associations are biologically plausible. Arsenic promotes carcinogenesis through genotoxic effects, interference with DNA repair, oxidative stress, and epigenetic changes. For cardiovascular disease, arsenic is linked to endothelial dysfunction, increased oxidative stress, inflammation, hypercoagulability, and dysregulation of vascular tone — mechanisms that can plausibly accelerate atherosclerosis, ischemic heart disease, and stroke. Reducing arsenic exposure should therefore diminish ongoing toxic insults and, over time, reduce incident and fatal outcomes.

Strengths of the study

• Repeated, individual-level biomarker measurements (urinary arsenic) over nearly two decades allowed direct assessment of temporal exposure changes rather than relying on baseline measurements alone.
• Large cohort with long follow-up and complete mortality surveillance through 2022.
• Natural experiment: community mitigation efforts reduced exposure for many participants, improving causal inference relative to a static-exposure observational design.
• Robust analytic approaches including time-varying Cox models, spline modeling, and propensity-score matching increased confidence that findings are not artifacts of modeling choices.

Limitations and cautions

• Observational design: Residual confounding is always possible. Although authors adjusted for important covariates and used propensity matching, unmeasured factors tied to both mitigation uptake and health (socioeconomic change, access to care, nutritional changes) could influence results.
• Measurement considerations: Urinary arsenic reflects recent exposure and metabolism; although repeated measures mitigate misclassification, short-term variability and reliance on creatinine correction can introduce bias, especially in populations with variable muscle mass or hydration.
• Latency and temporal dynamics: Cancer development often has long latency. The observed reductions in cancer mortality within the study period may reflect reductions in progression or mortality among people with preclinical disease as well as fewer new cases; longer follow-up would help clarify timing of benefits by disease type.
• Generalizability: The cohort had relatively high baseline exposures. Effect sizes in populations with lower baseline arsenic exposure might differ.
• Cause-of-death attribution: While mortality surveillance was robust, misclassification of cause of death is possible in community settings and could bias cause-specific estimates.

Implications for clinicians and public health policy

This study provides strong, actionable evidence that efforts to reduce arsenic exposure from drinking water can produce substantial reductions in mortality from major chronic diseases. Implications include:

• Public-health prioritization: Strengthen policies and programs to identify contaminated wells, provide safe alternative water sources, and sustain community-level mitigation to achieve reductions to guideline levels (for example, the World Health Organization guideline of 10 µg/L where feasible).
• Screening and surveillance: In high-exposure regions, implement population-level testing and mapping of wells, targeted remediation, and longitudinal health surveillance to track outcomes after mitigation.
• Clinical awareness: Clinicians in affected regions should be aware of arsenic as a modifiable environmental risk factor for cancer and CVD. Counseling patients on water choices and connecting them with mitigation programs can be part of preventive care.
• Equity and implementation: Many high-exposure communities are socioeconomically disadvantaged. Programs must prioritize equitable access to safe water and fund infrastructure and maintenance to ensure sustained exposure reductions.

Research gaps and next steps

• Mechanistic studies: Further research on the reversibility of molecular and subclinical cardiovascular and carcinogenic processes after exposure reduction will clarify the biology underpinning observed mortality declines.
• Intervention trials and implementation science: While randomized water-intervention trials face logistical and ethical constraints, pragmatic trials of mitigation strategies and implementation research to optimize uptake and sustainability are warranted.
• Longer-term follow-up: Additional follow-up will clarify the time course of benefits for specific cancers and for other chronic outcomes (e.g., diabetes, chronic lung disease).
• Exposure thresholds: Studies across exposure ranges are needed to refine safe-level targets and to assess whether health gains persist at lower absolute exposure differences.

Conclusion

Wu et al. provide compelling longitudinal evidence that reductions in arsenic exposure, as measured by urinary arsenic, are associated with substantial decreases in mortality from chronic diseases, including cancer and cardiovascular disease. The study strengthens the rationale for urgent, sustained public-health action to eliminate arsenic-contaminated drinking water sources and to monitor health benefits following mitigation. For clinicians, public-health practitioners, and policymakers, the findings underscore that reducing environmental toxicant exposure can translate into meaningful population-level health gains.

Funding and clinicaltrials.gov

Funding: Detailed funding sources and disclosures are reported in the original article (Wu F et al., JAMA 2025). Readers should consult the published paper for complete funding and conflict-of-interest statements.

ClinicalTrials.gov: This prospective cohort study is observational; any registration details or ancillary trial identifiers are available in the original publication.

References

1. Wu F, van Geen A, Graziano J, Ahmed KM, Liu M, Argos M, Parvez F, Choudhury I, Slavkovich VN, Ellis T, Islam T, Ahmed A, Kibriya MG, Jasmine F, Shahriar MH, Hasan R, Shima SA, Sarwar G, Navas-Acien A, Ahsan H, Chen Y. Arsenic Exposure Reduction and Chronic Disease Mortality. JAMA. 2025 Nov 17. doi: 10.1001/jama.2025.19161. Epub ahead of print.

2. World Health Organization. Arsenic. WHO Fact sheet. Accessible at: https://www.who.int/news-room/fact-sheets/detail/arsenic (accessed 2025).

3. National Research Council. Arsenic in Drinking Water. National Academies Press. (Foundational review on health effects and regulatory considerations.)

Readers interested in programmatic or clinical implementation details should review the primary JAMA article for full methods, supplementary analyses, and author disclosures.