Millions in Bengal exposed to pesticide-laden river water and groundwater: Report
The IIT team found in some of the water samples the levels of pesticides such as atrazine and malathion were at least 46 times higher than the permissible limits prescribed by the World Health Organisation (WHO), which is 0.9 mg per litre of water.Updated: Feb 15, 2020 13:58 IST
At least 20 million people in south Bengal, including those living in Kolkata, are potentially exposed to high doses of pesticides, insecticides and other pollutants present in the groundwater and in river Hooghly, says a new study published by Indian Institute of Technology, Kharagpur.
The IIT team found in some of the water samples the levels of pesticides such as atrazine and malathion were at least 46 times higher than the permissible limits prescribed by the World Health Organisation (WHO), which is 0.9 mg per litre of water.
These pesticides are commonly used to control mosquitoes and insects that attack fruits and vegetables.
“Though groundwater pollution has long been suspected it has been only sporadically reported so far. This study provides one of the first documentation of widespread existence and distribution of persistent organic pollutants (PoP) in the River Hooghly (a distributary of River Ganges in West Bengal) and ground water of the West Bengal basin. At least 20 million people are potentially exposed to this extremely high level of water pollution,” said Abhijit Mukherjee, associate professor at school environmental science and engineering at IIT Kharagpur and the principal investigator of the study.
The four-member research team collected river water samples from 32 locations and groundwater samples from at least 235 locations between 2014 and 2016 from various districts including Murshidabad, Nadia, North 24 Parganas, South 24 Parganas and Kolkata located across the lower Gangetic river basin that spreads over 21,000 sq km in south Bengal.
“An estimated 53% of urban and 44% of rural residents (approximately 20 million population), including those in cosmopolitan areas of Kolkata are potentially exposed to PoPs pollution in water, in addition to groundwater arsenic pollution exposure known from this area,” he added.
These districts are already known to be exposed to arsenic in drinking water.
“Groundwater samples were highly contaminated by insecticides such as malathion in urban and peri-urban areas. Herbicides such as alachlor and atrazine and insecticides such as malathion were found to be higher in agricultural areas. In contrast fluoranthene, one of the most common polyaromatic hydrocarbons (PAHs), was found abundantly in the urban areas. Pesticide concentrations were higher in the river water samples than that of the groundwater. Pesticide pollution in river water was higher in rural areas compared to urban areas,” said Srimanti Duttagupta, first author of the study.
“While malathion was the predominantly detected pesticide with concentration up to 46 times higher than the (WHO) permissible limit, PAHs such as naphthalene and phenanthrene were mostly found in urban and peri-urban areas,” Mukherjee added.
The researchers said myriad sources including vehicular pollution, biomass burning, domestic and industrial coal combustion apart from agricultural activities could be the reason for this pollution. These eventually affect the river and groundwater. Surface-runoff is attributed to be the primary reason for pesticides and PAHs contamination in rivers.
The alluvial plains of the lower reaches of the Ganges River in West Bengal are one of the most agriculturally fertile regions of South Asia. South Bengal is one of the most densely populated places in south Asia.
“Agriculture, industries and infrastructure development are bound to trigger some amount of pollution. We cannot stop that. The issue is how do we mitigate and find a balance. The water that reaches the consumer should be pollution free and for that even the World Health Organisation has suggested water safety plan which tends to identify the sources of pollution and mitigate them,” said Arunabha Majumder, former director and professor of All India Institute of Hygiene and Public Health (AIIHPH).
The study has been published this month in Science of the Total Environment, an international peer-reviewed journal of Elsevier.