Mutagenicity of Monocrotophos: A hazardous tea insecticide

Rishi Das

(rishidas66@gmail.com)

Though the Health Department is too concerned about the gradual surge of cancer cases in North East India, Assam in particular, and pinning on only the consumption of tobacco products as the main cause, extensive and prolonged use of banned pesticides for several decades in tea gardens with’ mutagenic effects’ may be a potential source of carcinogenicity. The ongoing impasse between the Assam Bought Leaf Tea Manufacturers’ Association (ABLTMA) and the Tea Board of India vis-à-vis the Food Safety Act and Rules (FSSAI) over the usage of banned pesticides is the major bone of contention.

Among the several organophosphate insecticides applied to tea bushes, monocrotophos is the most hazardous chemical. Monocrotophos is a fast-acting, cheap, and highly toxic cholinesterase-inhibiting organophosphorus insecticide that is readily water-soluble, quickly contaminates groundwater, and penetrates into plant tissues, making its removal impossible. Though monocrotophos sold under the trade names Azodrin, Apadrin, Pillardrin, Plantdrin, Crisodrin, Nuvacron, Monocron, and Bilobran are withdrawn by the EU, USA, and many other countries following warnings by the US Environmental Protection Agency (EPA) and WHO in 1985–1986,  in India, following the infamous monocrotophos poisoning and death at Vavatmal (Maharashtra) in 2017 and Gandaman (Bihar) in 2013, the government initiated steps to ban the hazardous pesticides after much dilly dallying.

The tea-growing zones of eastern India, including Assam and Arunachal Pradesh, and the Dooars region of North Bengal extensively use monocrotophos to control helopeltistheivora (the tea mosquito bug). The damage is widely spread in humid conditions, causing an estimated loss of 11 to 15 percent of the crop, especially after the monsoon during peak season, which became a concern for tea growers.

Global research, including in India, on monocrotophos established that accumulation of monocrotophos in living tissues poses a harmful threat to humans and adverse effects on non-target living systems present in the environment. It causes histopathological, acute genotoxic, cardiotoxic, hyperglycemic, and stressogenic effects in different living organisms. Though data is inadequate to establish oncogenic properties of Monocrotophos, it is a potential mutagen that caused DNA damage and chromosomal aberration in both bacterial and mammalian cells in in vitro studies. However, whether Monocrotophos inducing gene (point) mutation is equivocal besides predictive values for carcinogenesis can be assayed on the degree of mutagenicity as some mutations are precursors to carcinogens. The chromosomal aberration and DNA alteration could be useful sensitive biomarkers of Monocrotophos in determining its effects on humans with reference to cytotoxicity and genotoxicity. 

 India has finally banned its use via notification on September 29, 2023, published on October 10, 2023, albeit with a one-year transition period allowing use of monocrotophos until these stocks are exhausted, while the Department of Agriculture Government of Assam issued notification on 5.4.2023 restricting the use of four organophosphorus groups of insecticides, namely monocrotophos, quinolphos, profenophos, and navigphos, for two months. The local agricultural department reportedly pounced on a few selected wholesale dealers, sealing their warehouses allegedly unethically only recently, almost a year later; however, keeping the retailers untouched, the supply line remained functional. According to a source, a huge quantity of Monocrotophos has been procured by small tea growers, privately owned tea garden owners, and company gardens and is being hoarded for future use. 

Despite its ban, Monocrotophos was categorised as highly hazardous by FAO and WHO in 2005 and, among the mutagenic pesticides, continued to flourish in the market as its enforcement was limited. Over the years, India has allowed Monocrotophos to be used on a large variety of crops and vegetables, including tea, due to its cost-effectiveness and pest control efficacy. The government was influenced more by political, socio-economic, and agricultural yields than environmental safety in cotton and sugarcane-growing areas, where discounted loans from pesticide traders and money lenders attracted extensive borrowing by poor farmers, while the tea sector was almost ignored as it was under the control of corporate giants.

The ban did not deter the manufacturers from supplying the pesticide online. According to major pesticide dealers in Tinsukia, all tea gardens belonging to small tea growers (STG), private big estates, and corporate ownerships desperately used Monocrotophos till a ban was imposed to combat the Tea Mosquito Bug (Helopeltis theivora) that caused devastation in tea bushes, resulting in losses of 11–15 percent in production during peak season, especially after heavy rain. Tinsukia district, along with the tea-growing districts of Arunachal Pradesh, particularly Changlang and Lohit district, experience heavy rainfall, and breeding of the bug increases manifold; thus, these areas are fully dependent on Monocrotophos application without any alternative replacement. This is evident from FSSAI reports that failed to maintain the maximum residue limit (MRL).

Taking the lacuna in the government notification pertaining to the ban subjecting a one-year transition period ending October 2024 with no bar in marketing, a huge quantity of monocrotophos had been procured by garden owners in Tinsukia district and Arunachal Pradesh online irrespective of garden status, according to a source informing further that the huge monocrotophos consignments that were in stock with the dealers in Tinsukia and supposed to be returned to the manufacturers were despatched to the gardens of North Bengal by the manufactures’ representatives where the banning order of the Assam Government is not in force.

The Tinsukia Agriculture Department launched an extensive awareness campaign among the small tea growers in the district on the manifestation of the Monocrotophos application but expressed concern that the tea leaves of Arunachal Pradesh, supposedly contaminated with banned pesticides, are processed in the Bought Leaf Factories (BLFs) in Tinsukia district and blended with Assam tea leaves in the absence of any BLF in tea growing areas of Arunachal Pradesh.