New study finds toxic metals in some vegetables grown in galamsey areas

A review of 45 scientific studies has found toxic metals in tomatoes, pepper, garden eggs and onions grown in some communities affected by illegal mining, widely known as galamsey, in Ghana, raising concerns about the safety of vegetables consumed daily by many households.

The study published in the Environmental Monitoring and Assessment Journal on October 20, 2026, found that lead, arsenic and mercury levels in tomatoes, pepper, garden eggs and onions exceeded World Health Organization (WHO) and Food and Agriculture Organization (FAO) Codex limits at several sites, particularly in the Ashanti and Western Regions.

According to the review at the most contaminated sites, arsenic levels reached up to 200 times the applicable limit, while mercury levels were up to 400 times the limit.

The findings are contained in a study titled “Potentially toxic element contamination in Ghana’s vegetable value chain: a systematic review of mining-related soil-to-food transfer and human health risk.”

The study, led by researchers including Eric Osei Bonsu of the CSIR-Crops Research Institute in Kumasi, examined how mining activities could introduce toxic metals into vegetables through contaminated soil and irrigation water.

The researchers reviewed 45 peer-reviewed studies covering 11 mining districts, focusing on research published between January 2020 and January 2025.

They examined five metals: lead, cadmium, chromium, mercury and arsenic.

The study also raised concerns about farming in areas where galamsey and vegetable production take place side by side.

In some communities, farmers grow vegetables close to mining sites or use streams that may have been contaminated by mining waste Cadmium levels in tomatoes and garden eggs.

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Cadmium recorded the highest soil-to-plant transfer among the five metals in tomatoes and garden eggs, with transfer factors above 1.0.

This means the concentration of cadmium in the vegetables could be equal to or higher than that in the soil in which they were grown.

Chromium showed lower transfer into vegetables, with transfer factors below 0.50, even at some sites where soil concentrations exceeded 300 milligrams per kilogram.

The researchers want soil, irrigation water and vegetables to be tested more regularly in mining-affected farming communities.

They also recommend better handling and washing of harvested vegetables to remove contaminants on their surfaces.

However, they noted that washing cannot remove metals that have already been absorbed into the edible parts of a plant.

They further called for buffer zones between mining sites and farms to be determined by the level of contamination at each location rather than by applying the same distance everywhere.

JKB/VPO

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