Scientists from Brazilian and Spanish universities examined whether staple crops grown close to the Doce River estuary remain safe to eat after the 2015 Fundão tailings dam collapse. The disaster left a thick layer of iron‑oxide waste on farmland in Linhares, Espírito Santo, raising concerns about hidden metal exposure.
What the researchers tested
The team focused on three widely consumed foods – bananas, cassava (manioc) and cocoa pulp – and measured five potentially toxic elements (PTEs): cadmium, chromium, copper, nickel and lead. These metals are typical constituents of the mining tailings that have seeped into the soil.
How the analysis was performed
Soil and plant samples were collected from fields bordering the river. After washing, the fresh material was weighed, dried, and ground into a fine powder. The powder was dissolved with a mixture of strong acids, and the resulting solution was analysed with atomic spectroscopy to quantify metal concentrations per kilogram of dry biomass.
Key findings
In bananas and cassava, most metals accumulated in the underground parts – roots and tubers – while cocoa showed higher loads in stems, leaves and the fruit pulp. Notably, copper and lead in cocoa pulp exceeded the limits established by the Food and Agriculture Organization. For bananas, lead and cadmium concentrations were also above the recommended thresholds.
Health risk assessment
The scientists calculated three risk metrics – risk quotient (RQ), risk index (RI) and total risk index (TRI) – for two population groups: children under six and adults over 18. Using local consumption data, body‑weight averages, and exposure duration, they compared estimated intakes with safe reference doses.
Most TRI values stayed below 1, indicating low non‑carcinogenic risk for adults. However, the TRI for bananas exceeded 1 in the children’s group, chiefly because of lead, with cadmium contributing as well. Chronic exposure to even low levels of lead can impair brain development, lower IQ, and trigger attention‑related disorders.
Potential long‑term consequences
Beyond immediate toxic effects, the researchers warned that lifelong consumption of contaminated produce could raise the probability of DNA damage, which in turn might increase the risk of cancers affecting the nervous system, digestive tract, and blood‑forming tissues.
This work, published in Environmental Geochemistry and Health, underscores the importance of continuous monitoring of food grown in post‑disaster landscapes and the need for remediation strategies that protect the most vulnerable members of the community.