ANALYSIS/ARSENIC
mination is our dependence on groundwater to cater to water needs. Modern groundwater-based irrigation techniques and a gradual shift from a rainfed crop to multiple irrigated crops has increased the crisis.
Regular extraction of groundwater using “shallow large diameter” tube wells for irrigation is increasing the deposits of arsenic in soil and consequently its uptake by the crops being grown on that soil. In 2005, a paper published in
based on a study conducted in Murshidabad district of West Bengal highlights the positive correlation between the level of arsenic in groundwater and in agricultural soil and in various plants grown on them. Further, the flow-irrigation techniques utilised for crops like paddy is a long-term irrigation process which allows the soil to be flooded with contaminated water.
It eventually causes photoaccumulation of arsenic in the food crops, say A K Ghosh and S Singh in their paper published in
in 2011. Bioaccumulation of arsenic in plants, especially in the leaves, can emanate from contaminated water sprayed on them, says T Roychowdhury in a paper published in
in 2008. Thus a chain for transfer of arsenic from water to food is facilitated when farmers use contaminated water for irrigation. The ramifications of this transfer of poison are multifold. Coincidentally, the GBM plains are conducive to agriculture which is why field crops such as rice, maize, lentils and wheat and horticultural crops are widely cultivated across these states.
But what is grown in these states is laced with hazardous arsenic. A study published in
in 2008 found rice—even in boiled rice— vegetables and pulses contaminated with arsenic. Arsenic content in boiled or cooked rice was approximately 2.1 times that of raw rice grains. The accumulation of arsenic begins from the time the rice is washed in contaminated water. A study conducted by A K Ghosh and S Singh in Bihar and published in in 2011 has revealed that wheat has the highest retention of arsenic. The retention levels reduce from rice husk, rice grains to lentils with minimum retention in maize.
DIFFUSED CONTAMINATION The entry of arsenic into the food chain, in addition to drinking water, presents an array of consequences, the most alarming of which is the shift of arsenic—from a point source contamination in terms of drinking water—to a more diffused source contamination in the case of food products, with possibilities of biomagnification, says S K Sanyal in a study published in
in 2018. Juxtaposing the presence of arsenic in food crops into the currently larger problem of arsenic contamination in drinking water show that the spread of arsenic is much wider and beyond the GBM basin. But there are no estimates of diffused arsenic contamination of our food chain through food products.
A deeper look into the food web reveals rice husk—containing high levels of arsenic—is being used as fodder for livestock, exposing them to the hazardous impacts of arsenic contamination. This is also leading to a potential risk for humans when they consume cattle based food products. While research in this domain is nascent, the potential risk of arsenic contamination is unsettling due to its implications.
This implies mitigation measures—that are currently focused on drinking water—must have a more comprehensive approach to ensure arsenic-free water for drinking and agricultural products. That means that the government must check for arsenic in water used for agricultural produce. Both the Union and state governments must work toward facilitating research that can investigate the accumulation of arsenic in crops and addressing the agricultural concerns of the affected regions. They must watch out for arsenic percolation in the food chain and the possibilities of biomagnification. The government needs to also conduct a larger study on the arsenic contamination of our food chain and its health impacts to understand its spatial spread through the agricultural supply chain. As the poison is spreading, the clock is ticking too.
THE GOVERNMENT NEEDS TO INITIATE A LARGER STUDY ON THE IMPACT OF ARSENIC CONTAMINATION THROUGH THE FOOD CHAIN TO UNDERSTAND ITS SPATIAL SPREAD