BTA Admin 
A review of 45 scientific studies has found that vegetables grown in mining-affected communities across Ghana may contain dangerous levels of toxic metals linked to contaminated soil and irrigation water, raising concerns about food safety and the health of consumers.
The study, published in the journal Environmental Monitoring and Assessment, examined how five potentially toxic metals — lead, cadmium, chromium, mercury and arsenic — move from polluted soil and water into commonly eaten vegetables, including tomatoes, peppers, garden eggs and onions.
The findings add another dimension to Ghana’s illegal small-scale mining crisis, popularly known as galamsey. Beyond its widely reported impact on rivers and forests, mining-related pollution may also be affecting food produced for local consumption.
The research was conducted by Eric Osei Bonsu, a research assistant and scientist at the CSIR-Crops Research Institute in Kumasi, alongside co-authors Michael Kwabena Osei, Harry Okyere and James Korang.
Cadmium poses a major concern for consumers
The review found that cadmium recorded the highest soil-to-plant transfer in tomatoes and garden eggs, with transfer factors exceeding 1.0.
In simple terms, this means the concentration of cadmium in these vegetables could be equal to or higher than the concentration in the soil in which they were grown.
Cadmium is a toxic metal that can accumulate in the body over time. Prolonged exposure can damage the kidneys and contribute to other health problems.
The researchers also found that lead, arsenic and mercury exceeded World Health Organization (WHO) and FAO Codex limits for vegetables at several locations, particularly in parts of the Ashanti and Western Regions.
At the most contaminated sites reported in the reviewed studies, arsenic levels reached up to 200 times the applicable limit, while mercury levels reached up to 400 times the limit.
These figures relate to the most contaminated sites identified in the reviewed research and should not be interpreted as representing all vegetables or every mining community in Ghana.
Regular consumption could increase health risks
The researchers assessed the combined potential health risks associated with exposure to multiple metals through vegetables grown near mining activities.
In every mining-adjacent community where a cumulative hazard index could be calculated, the index exceeded 1.0. According to the study, this indicates an elevated potential for non-cancer health effects among people regularly consuming vegetables from those locations.
The finding is particularly relevant for communities where households depend on locally grown food and where farmers may use water from rivers, streams or other sources affected by mining-related pollution.
However, the review assessed potential health risks based on the available environmental and food-contamination studies. It does not establish that every person who eats vegetables from a mining district will develop an illness, nor does it independently confirm the extent of exposure among individual residents.
Chromium findings leave unanswered questions
The review found that the transfer of chromium from soil into plants was generally low, even at sites where soil concentrations exceeded 300 milligrams per kilogramme.
But the researchers cautioned that this result may not tell the full story.
Most of the studies reviewed did not distinguish between trivalent chromium and hexavalent chromium, two different chemical forms with substantially different toxicity profiles. Hexavalent chromium is considerably more toxic and is a known human carcinogen.
Without identifying which chemical forms are present, measuring total chromium alone may fail to provide a complete picture of the potential health risk.
The researchers therefore called for more detailed testing to establish the forms of chromium and arsenic present in contaminated environments and food crops.
What should Ghana do about contaminated vegetables?
The study recommended targeted monitoring and stronger measures to reduce the risk of contaminated food reaching consumers.
- Test vegetables, soil and irrigation water in mining districts
The researchers argued that monitoring should focus on areas affected by mining rather than distributing testing resources evenly across the country. This could help authorities identify high-risk locations and determine which crops and water sources require closer attention.
- Improve washing and handling of vegetables
Proper washing and post-harvest handling may reduce contamination on the surfaces of vegetables before they reach markets and consumers.
However, washing cannot reliably remove metals that have already been absorbed into the internal tissues of a plant. This means contaminated soil and irrigation water must also be addressed.
- Establish agricultural buffer zones using local evidence
The researchers recommended setting buffer zones around mining sites based on actual contamination measurements rather than applying one fixed distance to every location.
This approach would allow authorities to account for differences in soil conditions, water contamination and the spread of pollution from one mining area to another.
Researchers call for further investigation
The review also identified important gaps in existing research.
These include the need to identify the chemical forms of chromium and arsenic, improve assessments of how several toxic metals may affect people when exposure occurs simultaneously, and conduct long-term human biomonitoring in affected communities.
Human biomonitoring involves measuring substances or their indicators in people, helping researchers establish whether environmental contamination is translating into actual exposure.
Such studies could provide a clearer link between the metals found in food and soil and the levels detected in people living in mining-affected communities.
Galamsey debate must include the food on Ghanaian plates
Illegal mining is frequently discussed in terms of destroyed forests, polluted rivers and the cost of restoring damaged land. The new review suggests that food safety also deserves greater attention.
If soil and irrigation water become contaminated, the effects may extend beyond the mining site to farms, markets and households that depend on locally produced vegetables.
The researchers’ findings do not mean that all vegetables grown in Ghana’s mining districts are unsafe. They do, however, highlight the need for targeted testing, better environmental monitoring and stronger evidence about the risks facing affected communities.
Mr Bonsu said the research was a team effort and thanked his co-authors and colleagues at the CSIR-Crops Research Institute and the CSIR College of Science and Technology.
“Galamsey is usually discussed in terms of rivers and forests. Our hope is that this review places the food on Ghanaian plates firmly within that conversation,” he said.
