The report, titled ‘Living in a cleaner environment in India: A strategic analysis and assessment’, says that levels of nickel, manganese and lead in Yamuna’s water were found to be higher than the international aquatic water quality criteria for fresh water. Meena Sehgal, a consultant with TERI who worked extensively on the report, says that their focus was on heavy metals found in the environment and through what means they enter the human body. “Our findings made it clear that it is essentially green leafy vegetables that contain the highest amount of metals. This is because such vegetables have a high tendency to accumulate metals. Levels were significantly lower in other vegetables and practically negligible in drinking water samples,” she said.
The study took 13 samples at a 2km distance along the 22km stretch of Yamuna that flows through Delhi. Samples were also collected from Dayalpur and Chandawali villages in Ballabhgarh district of Haryana, about 25km away from Delhi, to compare with those collected from the urban sector. “Levels of nickel, manganese, lead and mercury were above the permissible international standards in agricultural soil along the river. While moderately high levels of contamination were recorded in urban areas, the rural areas showed negligible levels. High levels of these pollutants in the floodplains can be associated with treated and untreated effluents or with sewage flowing into the river,” says the report.
The study identified Wazirabad and Okhla barrage as the hotspots for soil contamination. This, says the team, is possibly due to the discharge of huge amounts of industrial effluents at the two locations from the Najafgarh and Shahdara drains.
“Vegetables grown in the floodplain of the Yamuna area show higher levels of heavy metal contamination than those cultivated in rural areas, thus, acting as the point of entry for toxic metals into human food chain. Bio-monitoring of women and children in the study area showed significantly higher levels of heavy metals in urine and blood samples taken in urban areas compared to rural areas,” said Sehgal.
The report says that soil samples exceed the limit for nickel and copper at most sites, and less often for zinc, manganese and lead. The quantity of lead varied from below-detection levels to 114.6 mg/kg, with some locations recording a prevalence more than 40 times the lowest level along the 22km stretch. The hexavalent chromium levels in soil samples at different locations ranged from 4.52 mg/kg to 35.29 mg/kg. Levels of more than 25 mg/kg have been found to be have adverse effects on health. Soil concentrations of mercury largely ranged between 0.43 mg/kg and 82.06 mg/kg. These levels were much higher than the 1 mg/kg stipulation at all the locations.
Lead has been known to impair motor skills and result in hypertension. Cadmium leads to renal damage, osteomalacia and loss in sense of smell. International Agency for Research on Cancer has classified cadmium as a human carcinogen.
