GSI team finds dangerous levels of lead in raw food items in Kolkata markets
The team of scientists pinpointed exhausts from vehicles running on diesel as the principal source of lead.kolkata Updated: Oct 25, 2017 14:19 IST
Raw food items such as rice, red lentil, chicken, fish, biscuits, spice sold in roadside markets of Kolkata contain high levels of lead, prolonged consumption of which can permanently damage kidneys, liver and the blood system, a recent study by Geological Survey of India (GSI) has found.
Lead is a highly toxic element that is especially harmful to children, who can even suffer reverses in brain growth on regular exposure to lead.
The findings of this rare study are alarming. While the acceptable levels of lead in blood are pegged at less than 0.05 mg/litre for children and less than 0.25 mg/litre for adults, the presence of the element varied from a minimum of 5 times (in fish) to 2,911 times (in vegetable) of that limit.
The GSI team identified diesel exhausts of the city traffic and soil in the nearby areas where vegetable is grown as the major sources of excessive lead. “The lead has come from diesel exhausts. This type of study is rare in the world. A few have been conducted in the US and France. A new machine has helped us to pinpoint diesel as the chief source of lead and there is no ambiguity in the findings,” Dipayan Guha, director of geochronology and isotope geology division of GSI told HT.
The outcome of the study, conducted by project director Dipayan Guha and a team of six scientists, was published in Environmental Science and Technology and Environmental Science and Pollution Research. The studies began in 2014 and continued till March 2016.
In rice the presence of lead was a minimum of seven times (of the limits for adults) to a maximum of 30 times. It implied a level that is 36 times to 149 times of the safe limits for children. The presence of the element in chicken is as high as 38 times the permissible limit for adults and 191 times of that for kids.
“The maximum Pb concentration in rice was 14.39 mg/kg in the Khidirpur sample from west Kolkata…. Vegetables sold in the sampled markets had a Pb concentration ranged from a low of 3.28 mg/kg to a very high value of 145.47 mg/kg…,” read a GSI statement.
The GSI team collected samples of polished rice, red lentil (masoor dal), chicken, fish (without scales), spinach, biscuits, spices (cumin seeds) and tulsi from 12 roadside markets from north, south, east and west of Kolkata.
“Even if one washes the items in water, one can get rid of 50% of the lead,” said Guha.
The maximum concentration of lead was found in the soil at and near Dhapa, the city’s principal dumping ground.
The GSI team also found the lead content in the street dust alarming. “The mean concentration of Pb found in the 29 sites was 383.2 mg/kg with a range from 23.82 mg/kg to a very high value of 2,697.24 mg/kg at Amherst Street in north Kolkata,” a GSI release said.
The GSI spokesperson told HT that they chose samples from the roadside markets since common people buy from these.
“Since much of the contamination is caused by exposure to air, one can expect that packaged items sold in closed conditions will have less lead,” said the spokesperson.
Kalyan Rudra, chairman of the state Pollution Control Board, told HT there was no immediate relief in sight. “CNG is not available in Kolkata and is only expected to reach here in 2020. Even after it reached the city, it will take a lot of time for the commercial vehicles to switch from diesel to CNG. The autorickshaws, however, have already to LPG,” said Rudra.