Can food grown in areas affected by an environmental disaster be consumed?
A scientific team has investigated this pressing question for the inhabitants of the Brazilian region of the Rio Doce estuary, where a mining waste dam collapsed ten years ago. Their work focused on local crops like banana, cassava, and cocoa, to assess how plants absorb toxic elements from contaminated soils.
This team therefore analyzed these agricultural products to determine if they could pose a danger. Their research focuses on the transfer of potentially toxic elements, present in soils polluted by mining discharge, to the edible parts of the plants. This phase is necessary to understand the concrete dangers for populations who incorporate these foods into their regular diet.
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The soils in the region show high levels of cadmium, chromium, copper, nickel, and lead. These metals are strongly associated with iron oxides, which make up the majority of the spilled mining waste. According to the analyses, consuming bananas from these lands could pose a health problem, especially for young children under six years old. For adults, the threat seems more limited, but special attention is still necessary.
It should be noted that plants do not accumulate contaminants in the same way. In bananas and cassava, most metals are concentrated mainly in the underground parts, like roots and tubers. In contrast, cocoa shows notable accumulations in its aerial parts: stems, leaves, and even the fruit. The cocoa pulp examined thus exceeded the recommended limits for copper and lead.
Scientists established risk indices by considering the quantity of food ingested, the duration of exposure, and body mass. For children, the index related to bananas exceeds the safety level, mainly due to the lead content. Repeated exposure to this element, even at low concentration, is known to have negative impacts on the development of the nervous system.
Over an extended period, the regular ingestion of these foods could contribute to a progressive health danger. The researchers mention the possibility of DNA alterations that could increase the frequency of certain cancers. These consequences depend on each organism's ability to absorb and transform the elements present in its environment.
Published in
Environmental Geochemistry and Health, this study is part of doctoral work that led to several publications. It seeks to provide practical data to guide choices related to food safety and the management of lands impacted by this type of pollution.