Key Update

Vegetables grown along a stretch of the Yamuna near Delhi contain multiple heavy metals at concentrations far above food safety limits, potentially exposing consumers to health risks, researchers from the University of Delhi have warned. The study focused on a small stretch of the Yamuna, a 1,379-km river that flows through seven states. However, the researchers said the findings raise concerns about similar contamination in other areas where farmers use polluted water to irrigate crops.

Heavy Metals Found Above Safety Limits

The researchers compared metal concentrations in vegetables grown along the Yamuna with limits set by the Food and Agriculture Organisation (FAO). They found nickel levels in potatoes at 181 times the prescribed limit, while red radish contained molybdenum at 68 times the limit. Nickel levels also exceeded the limit by 97 times in spinach and 65 times in onions. Chromium levels were 22 times the limit in mustard, 12 times in spinach and 11 times in white radish. Lead levels exceeded the limit by 10 times in potatoes and onions and seven times in spinach.

Polluted Irrigation Water Can Contaminate Crops

According to Dinabandhu Sahoo, professor in the botany department at the University of Delhi and supervisor of the study, metals from river water or wastewater used for irrigation can accumulate in the edible parts of vegetables. Sahoo said regular consumption of such vegetables could expose people to potentially toxic metals through their diet.

Sahoo said regular consumption of such vegetables could expose people to potentially toxic metals through their diet. He called for wastewater treatment, regular monitoring of irrigation water and crops, and guidance on growing safer crops in contaminated areas. The researchers also assessed potential health risks using earlier estimates of daily vegetable consumption and the possible effects of exposure to individual metals.

Their analysis identified molybdenum as the largest contributor to non-cancer health risks across most of the vegetables studied. It contributed more to the estimated risk than metals such as lead and cadmium. The researchers found the highest estimated cancer risk through red radish, with nickel and chromium emerging as the main contributors across most vegetables.

Study Focuses on a Polluted Yamuna Stretch

The study, published in Energy Nexus, examined vegetables grown along the Kalindi Kunj stretch in southeast Delhi, one of the Yamuna’s most heavily polluted sections. Industrial wastewater, inadequately treated domestic sewage, and urban runoff contribute to pollution in the area. The researchers found metal contamination in several commonly consumed vegetables, including spinach, mustard, radish, potatoes and cauliflower. They noted that different plants absorb and store metals differently, depending on their metabolism. According to Sahoo, understanding how different vegetables absorb metals could help authorities identify safer crops to grow in areas affected by metal contamination.

Researchers Flag Uncertainty Over Chromium Risk

The researchers also cautioned that their estimates of cancer risk from chromium carry some uncertainty. The study measured total chromium but did not distinguish between hexavalent chromium (chromium VI), which is more toxic, and trivalent chromium (chromium III), which is less toxic. Sahoo stressed the need for periodic monitoring of irrigation water and called for scientific measures to improve the quality of the Yamuna. The findings highlight how polluted irrigation water can transfer contaminants into crops, creating a potential food-safety concern beyond the river itself.

Source: The Telegraph Online