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Environmental and public health outcomes following the Fundao dam collapse (Mariana, Brazil): a retrospective ecological study of drinking water quality and cancer mortality

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This retrospective ecological study analyzed the long-term public health consequences of the 2015 Fundao tailings dam collapse in Mariana, Brazil (the largest tailings dam failure in history, releasing 60 million tons of mining waste into the Doce River Basin). The study used SISAGUA drinking water quality data (2014-2023) and SIM/DATASUS mortality data (2011-2023) for 203 municipalities in the Doce River Basin, compared with 17 comparison municipalities from other basins.

Key numbers

  • 874,879 water quality records covering 144 monitored micropollutants were extracted.
  • 65 contaminants identified at or above Brazilian Maximum Residual Limits (MRLs) in at least one Doce Basin municipality.
  • 41 substances selected for cancer risk estimation, including 10 metals/metalloids (arsenic, cadmium, lead, and others), 6 inorganic substances, 21 pesticides, and 4 organic compounds.
  • Primary metals detected exceeding Brazilian MRLs: arsenic, cadmium, lead, and antimony, together with aluminum, copper, chromium, iron, manganese, nickel, and vanadium.
  • All-cause mortality in Doce River Basin increased between pre-disaster period (2011-2014) and post-disaster period (2015-2023): +0.005 deaths per population (95% CI: 0.0022-0.0078, p = 0.028).
  • Approximately 300 total cancer cases attributable to drinking water contamination were estimated in the affected basin.
  • Cancer-specific mortality rates for ovarian, rectal, oropharyngeal, and central nervous system cancers were higher in affected municipalities than in comparison basins.
  • Formal difference-in-differences test was positive but non-significant (DID test), indicating caution in interpreting causality.

Methods (brief)

Retrospective ecological study; secondary municipal-level data from SISAGUA water quality surveillance database and SIM/DATASUS mortality registry. Cancer risk estimation using WHO/IARC benchmark drinking water guideline values (average pollutant concentration x population exposed x risk index). Comparative analysis with 17 municipalities from Grande and Jequitinhonha River Basins. Statistical R code provided; descriptive and comparative analyses. Ethical approval waived (secondary public data).

Evidence fitness

Supports: demonstrating that large-scale mining tailings dam failures cause sustained, multi-metal contamination of drinking water and may increase cancer mortality in affected populations. Arsenic is one of the primary metals identified. This paper is relevant to the inhalation and water exposure context for arsenic, not dietary food arsenic. The cancer outcomes include but are not limited to respiratory cancers.

Limitations

Ecological study design prevents causal attribution at individual level; no pre-disaster longitudinal water quality baseline; contamination characterized cumulatively across all SISAGUA measurements (not temporal trend); formal DID test non-significant; confounding by socioeconomic factors; small cancer sub-group sample sizes; focus on water exposure, not dietary food intake.

Update history

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