Vegetables Across Bengaluru Contaminated With Heavy Metals, Warns Study

In Bengaluru, the utilisation of wastewater for cultivating vegetables has resulted in a concerning surge in heavy metal concentrations within these crops. Researchers from the Environment Management and Policy Research Institute (EMPRI), who analysed 400 samples of 10 different vegetables, found out the levels of contamination exceeding the permissible limits set by the Food and Agriculture Organisation (FAO).

Bengaluru, which houses over one-fifth of the state's population, sources its vegetables from farmer networks situated in the peripheral regions of Bengaluru Urban, Kolar, Chikkaballapur, Ramanagara, and Bengaluru Rural. The primary supplier, Hopcoms, alone delivers 70 tonnes of vegetables. A substantial portion of the population relies on private retailers, ranging from pushcart vendors to supermarkets.

For their research, EMPRI scientists collected 400 vegetable samples from 20 locations across Bengaluru, encompassing five upscale supermarkets, five local markets, "organic stores," and Hopcoms. They meticulously examined 10 varieties of vegetables, including brinjal, tomato, capsicum, bean, carrot, green chili, onion, potato, spinach, and coriander, to gauge the presence of heavy metals.

Notably, the permissible limit for iron is set at 425.5 mg/kg, yet beans purchased from reputable organic stores registered an iron concentration of 810.20 mg/kg. Similarly, coriander recorded 945.70 mg/kg, and spinach exhibited 554.58 mg/kg. Among vegetables procured from Hopcoms, onions contained 592.18 mg/kg of iron. The presence of heavy metals exceeding permissible limits was observed in most of the sampled vegetables, irrespective of whether they were obtained from supermarkets or smaller retail outlets.

The FAO has established 0.2 mg/kg as the maximum allowable limit for cadmium. However, brinjal purchased from a supermarket in BTM Layout contained a staggering 52.30 mg/kg of cadmium. Coriander, spinach, and carrots also surpassed the permissible limits with readings of 53.30/kg, 53.50 mg/kg, and 54.60 mg/kg, respectively. Cadmium is a hazardous element that can lead to liver and lung toxicity, along with impairing the immune system.

Lead, described as "purely toxic," should not exceed 0.3 mg/kg. While it remained undetectable in several vegetables, beans from a supermarket exhibited a worrying 12.20 mg/kg concentration, raising health concerns for those who consume this vegetable regularly.

The concentration of nickel exceeded the recommended limit of 67.9 mg/kg in green chili, carrots, potatoes, tomatoes, and beans. The study highlighted that the edible portions of vegetables are prone to accumulating heavy metals, especially leafy greens. This phenomenon is attributed to the higher transpiration rate of these plants, which is required to support growth and moisture retention.

N Hema, the research scientist who led the one-year study, told DH that there is an urgent need for a broader investigation into three major aspects. Firstly, tracing the sources of these vegetables is crucial to ensure an evidence-based approach. Secondly, specific maximum limits for each vegetable and exposure duration should be established. Thirdly, the impact of vegetable consumption on children, adults, and the elderly needs to be thoroughly examined. Finally, a comprehensive study must be conducted to isolate the health implications of consuming such vegetables. The findings underscore the necessity to discourage the use of wastewater for irrigation and urge farmers to adopt ethical and safe farming practices. This warning holds particularly true for leafy vegetables, which are more susceptible to heavy metal accumulation due to their higher transpiration rates.