Why has the Centre restricted use of a herbicide?
Source: By Harish Damodaran: The Indian Express
The Union Agriculture Ministry has restricted the use of glyphosate, a widely used herbicide. This comes even as the Supreme Court on 10 November 2022 is about to take up a plea seeking a ban on all herbicide-tolerant crops, including transgenic hybrid mustard and cotton.
What is glyphosate?
It is an herbicide used to kill weeds — undesirable plants that compete with crops for nutrients, water and sunlight. Since weeds basically grow at the expense of crops, farmers remove them manually or spray herbicides.
Glyphosate is a broad-spectrum herbicide that can control a wide range of weeds, whether broadleaf or grassy. It is also non-selective, killing most plants. When applied to their leaves, it inhibits the production of a protein ‘5-enolpyruvylshikimate-3-phosphate synthase (EPSPS)’. This enzyme, produced only by plants and microorganisms, synthesises aromatic amino acids that are necessary for their growth.
Use in India
There are nine glyphosate-based formulations containing different concentrations of the chemical registered for use under the Insecticides Act, 1968. These are approved largely for weed control in tea gardens and non-crop areas such as railway tracks or playgrounds. Farmers also apply glyphosate on irrigation channels and bunds to clear these of weeds, making it easier for water to flow and to walk through them. Weeds growing on bunds are, moreover, hosts for fungi, such as those causing sheath blight disease in rice.
In general, though, the scope for glyphosate use is limited for the very reason that it is non-selective. Designed to kill all plants coming into contact with it, the chemical cannot ordinarily distinguish between crop and weed. Hence, it can be used in tea or rubber plantations, but not in fields where the crops and weeds are at almost the same level.
What exactly has the government now done?
The Ministry of Agriculture and Farmers Welfare, on 21 October 2022, issued a notification stating that “the use of glyphosate involves health hazards and risk to human beings and animals”. It has, however, not banned and only “restricted” its use. The spraying of glyphosate and its derivatives shall henceforth only be permitted through “pest control operators”.
Why has this been done?
As earlier noted, the scope for glyphosate is already restricted in normal agricultural crops by virtue of it being a non-selective herbicide. Glyphosate application has increased only with the advent of genetic modification (GM) or transgenic technology.
In this case, it has involved incorporating a ‘cp4-epsps’ gene, isolated from a soil bacterium Agrobacterium tumefaciens, into crop plants such as cotton, maize and soyabean. This alien gene codes for a protein that does not allow glyphosate to bind with the EPSPS enzyme. The said GM crop can, therefore, “tolerate” the spraying of the herbicide, which then kills only the weeds.
In 2019 alone, some 81.5 million hectares were planted worldwide with herbicide-tolerant (HT) GM crops. The global glyphosate market is annually worth $9.3 billion, with over 45 per cent of use on account of GM crops.
As far as India goes, the only GM crop officially under commercial cultivation today is Bt cotton. This has two alien genes (‘cry1Ac’ and ‘cry2Ab’) from the soil bacterium Bacillus thuringiensis, that code for proteins toxic to the American bollworm, spotted bollworm and tobacco caterpillar insect pests. In the 2022 kharif planting season, about 39 million Bt cotton packets — each containing 450 gm of seeds — were sold at a notified maximum retail price of Rs 810/packet.
But industry estimates suggest sales of an additional 5 million packets of “illegal” GM cotton seeds at prices ranging from Rs 1,100 to Rs 1,350/packet. These seeds harbour both insect-resistance and HT traits, coming from the two Bt genes and the glyphosate-tolerant ‘cp4-epsps’ gene.
Neither the Centre nor state governments have succeeding in stopping the cultivation of illegal HT cotton. The fact that their seeds (1.5 to 2 packets are sown on every acre) are selling at a premium is proof of farmers themselves wanting them. Given the high cost of manual weeding and non-availability of labour when required, they clearly see the value in spraying glyphosate and planting HT cotton. Having failed to curb the illegal sales of seed, the Centre is trying to nip the problem in the bud — by cutting the access of farmers to glyphosate and allowing its use only through pest control operators.
How valid are the health concerns over glyphosate?
The World Health Organisation’s International Agency for Research on Cancer (IARC), in March 2015, classified glyphosate as “probably carcinogenic to humans”. But this was based on evidence for cancer in experimental animals from “pure” glyphosate, as opposed to that in humans from real-world exposures through diluted formulations (which is how the chemical is actually sold and used).
The US Environmental Protection Agency, on the other hand, has held that there are “no risks of concern to human health from current uses of glyphosate” and “no evidence” of it causing cancer. Its findings are based on “a significantly more extensive and relevant dataset [than the IARC’s]”.
The European Chemicals Agency, too, has concluded that “classifying glyphosate as a carcinogenic, mutagenic (causing DNA changes) or reprotoxic substance is not justified”. For now, what’s not in doubt is the demand for herbicides and crops that can withstand their application among Indian farmers.
The Union Environment Ministry’s Genetic Engineering Appraisal Committee (GEAC), on 18 October 2022, recommended the commercial release of Delhi University’s GM hybrid mustard. This crop can also tolerate the spraying of glufosinate ammonium, a non-selective herbicide similar to glyphosate. GEAC is further set to take a call on approving glyphosate-tolerant Bt cotton, whose illegal cultivation is an open secret.
All eyes are next on the Supreme Court, scheduled to hear a plea challenging the GEAC’s nod for the transgenic hybrid mustard and also seeking a ban on all HT crops.
