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Current Affairs

Toxins in drinking water of Bengal basin

Date: 18 February 2020 Tags: Miscellaneous

Issue

Groundwater as well as river water in the western Bengal basin has high concentrations of pesticides and toxic polycyclic aromatic hydrocarbons (PAH), according to a study by Indian Institute of Technology (IIT), Kharagpur.

 

Background

The study assumes significance because, for the first time in the country, a whole region has recorded the presence of pesticides and PAH in its natural sources of water and surface sediments.

 

Details

  • The researchers tested hundreds of samples, both of groundwater and river water, which is used for drinking water supply from the Farraka Barrage to the Sunderbans, and found these chemicals in significantly higher amounts than permissible limits.

  • The results of this study suggest the existence of wide presence of POPs (persistent organic pollution pollutants), as pesticide residues and PAHs, detected both in groundwater and river water of areas, variable by land use, which are historically known to be at risk from groundwater arsenic pollution.

  • Samples from more than 230 locations for groundwater, 32 locations for river water and 20 locations for surface sediments across 350 km were recorded for three consecutive years and studied for the presence of pesticides and PAH.

  • In some samples, the pesticide content in drinking water was as high as 46 times of the permissible limits.

  • The groundwater and river water were tested only from locations at which water is sourced for drinking purposes.

  • Another important aspect of the study is that it shows spatio-temporal distribution of these chemicals detected predominantly in natural waters.

  • The study also points out that the pesticides and PAHs detected in agricultural and rural areas are distinct from urban settings.

  • While concentration of pesticides is higher in rural areas, particularly in agricultural areas in districts like Murshidabad and Nadia, as we go down, high concentration of PAH is found to rise in urban and semi-urban areas, particularly in North 24 Parganas and south Nadia.

  • This is one of the most populated regions of South Asia, and the presence of hazardous chemicals in groundwater raises concerns over anthropogenic pollution due to local vehicle combustion, biomass burning and industrial combustion, apart from agricultural activities.

  • while arsenic contamination is blamed for most of the deaths due to water contamination, the study provides another aspect for looking into how much pesticides and PAHs in drinking water contribute to the disease burden.