Bengal, Bihar most impacted by arsenic contamination: Centre to NGT

West Bengal and Bihar are impacted the most by arsenic contamination of groundwater, the Centre has informed the National Green Tribunal (NGT).

The tribunal is hearing the issue of rice being susceptible to arsenic contamination because it absorbs more of the toxic semi-metallic element from water and soil. Earlier, it sought a reply from the Centre on it.

In an order dated December 16, a bench of NGT Chairperson Justice Prakash Shrivastava and expert member A Senthil Vel noted that the Union Ministry of Agriculture and Farmers Welfare had filed its reply after seeking inputs from the Indian Council of Agricultural Research (ICAR).

"States of West Bengal and Bihar are reported to be most affected by arsenic contamination of groundwater irrigation by contaminated groundwater is the major route for arsenic entry into agricultural soil which ultimately leads to its entry into the food chain," the Centre said in its reply.

There can be a "significant build-up" of the toxic element in rice as it is a water-intensive crop, the reply stated.

"Transport of arsenic-contaminated rice grain grown in arsenic-endemic areas to non-endemic sites and consequent dietary intakes will also spread arsenic exposure in the non-endemic population," it noted.

The tribunal noted that, according to the reply, the distribution of arsenic content in plant parts generally followed the order of roots, stems and leaves.

"The edible parts of leafy (spinach, fenugreek etc.) and underground vegetables (beet, radish etc.) contained much higher arsenic as compared to vegetables with fruit as edible part (brinjal, beans, ladies' finger, tomato etc.). In general, fruit/grain of plants showed less accumulation of arsenic compared to root, stem and leaf," it noted.

The reply also suggested various remedial measures to minimise the effect of arsenic in the soil-plant system.

These include replacing water-intensive rice varieties with other less water-intensive crops and relatively arsenic-tolerant rice varieties, growing non-edible and leguminous crops during the dry season in the hotspot areas, application of biochar (modified charcoal produced from burning biomass sources), and increased use of green manures and application of silicate fertilizers.

The reply also suggested other remedial measures, such as storing arsenic-contaminated groundwater in ponds and subsequent dilution with rainwater along with conjunctive use of ground and surface water to dilute the arsenic content.

The tribunal then impleaded the ICAR as a respondent and sought its response. It will hear the matter next on April 15.