New Delhi, Sep 23 A study by University of Delhi (DU) researchers indicates significant heavy metal contamination in agricultural soil and vegetables cultivated along a stretch of the Yamuna in the capital, raising concerns over potential health risks to consumers of crops irrigated with untreated wastewater.
The study, published in the Energy Nexus journal, examined accumulation of heavy metals in commonly consumed vegetables and assessed their potential non-carcinogenic and carcinogenic risks.
The research team, led by Dinabandhu Sahoo, senior professor and head of the botany department in DU, analysed the presence of molybdenum, aluminium, zinc, nickel, chromium, cadmium and lead in the agricultural soil and vegetables grown along the Yamuna.
The study noted that Delhi accounts for around one per cent of the Yamuna’s catchment area but contributes approximately 70-80 per cent of the river’s pollution load. Farmers in peri-urban areas depend on the polluted river-water for irrigation, resulting in transfer of contaminants into agricultural soil and crops.
The researchers found that the absorption of heavy metals varied across plant species.
Nickel accumulation was particularly high in onions and spinach, while elevated chromium levels were recorded in white radish, spinach and mustard, according to the study.
Red radish recorded molybdenum levels of up to 340.06 milligram (mg) per kg and chromium levels of 36.58 mg per kg, which are extremely high. Fenugreek showed dangerous zinc levels, with accumulation of up to 177.72 mg per kg.
Coriander recorded nickel levels of 19.91 mg per kg and cadmium levels of 1.59 mg per kg, while mustard showed lead accumulation of up to 5.86 mg per kg.
The study also assessed potential health risks associated with consuming the contaminated vegetables.
Hazard Index (HI), which measures combined non-carcinogenic risks arising from exposure to multiple contaminants, exceeded safe limits in the assessment. Researchers attributed the findings primarily to dietary exposure to molybdenum across several vegetable varieties.
“Further, the study identified unacceptable cancer risks tied to the consumption of these vegetables, largely due to high levels of nickel and chromium,” researchers said.
Total Carcinogenic Risk (TCR) values were reported to be highest for red radish at 0.17, followed by coriander at 0.16, and spinach and white radish at 0.14 each.
Researchers said heavy metal concentrations recorded in the vegetables were several times higher than the prescribed limits of the Food and Agriculture Organization (FAO).
Sahoo said farmers in identified contamination hotspots should consider cultivating crops that accumulate lower levels of heavy metals to reduce dietary exposure.
“Continuous governmental monitoring of soil and crop quality and strict enforcement of pollution controls at the river source is need of the hour,” he said.
The study called for coordinated interventions, including regular monitoring of agricultural soil and vegetables, safer irrigation practices and stronger pollution control measures.
The research team included Sahoo, Dharmendra Kumar, Sanjukta Sahoo and Shivankar Agrawal, bringing together experts in botany, environmental engineering and microbiome research.
The study examined only a limited stretch of the Yamuna — a 1,379-km river flowing through seven states — and its findings do not necessarily represent contamination levels across the entire river basin.
(PTI News)
