"Tell people that a person up there created the universe and they'll believe you but tell them that it is 'wet paint' and they'll want to touch it to believe you"
The term 'agro-chemical' refers to a variety of chemical substances, and includes fertilizers, and pesticides (insecticides, herbicides (weedicides), fungicides, nematicides) etc. They came into widespread use and prominence with the advent of modern ('green revolution') agriculture.
The media in Sri Lanka (print and electronic) has been agog recently with calls to ban various agro-chemicals. Sadly, those making the biggest noise, appear to be the least informed on the subject, and this country is rapidly acquiring the dubious reputation of a land where demagogues rule the roost.
To ban or not to ban
The decision of what should be banned and not banned must be entrusted to competent professionals having the capacity to make logical and dispassionate assessments based on sound scientific evidence. It is also essential to ensure that such persons must be men and women of high integrity, firmly committed to the national interest.
The Pesticides Technical Advisory Committee (comprising 15 members drawn from institutions such as the Department of Agriculture, Ministry of Health, Govt. Analyst's Department, Tea, Rubber and Coconut Research Institutes, Sri Lanka Standards Institute, Environmental Ministry, Commissioner of Labour and Five nominees of the Ministry of Agriculture) is the duly authorized body for recommending the import or banning the use of any pesticide within the country. Sadly, its authority has been usurped by politically powerful elements with vested interests (during the previous government). The new government (committed to 'Yahapalanaya') needs to ensure that such institutions are permitted to perform their legitimate functions without fear or favor.
Foremost among the list of agro-chemicals facing the threat of banning, is the herbicide Glyphosate. Those who advocate the banning of Glyphosate do so on the assumption that it causes Chronic Kidney Disease of Uncertain Etiology (CKDu). More recently, it has also been purported to "probably cause" cancer. Let's consider these assumptions objectively.
What is Glyphosate?
Glyphosate is a broad-spectrum(indiscriminately affecting all plants coming in contact with it), systemic herbicide (extensively translocated throughout a plant). It was invented in 1970 by John E. Franz, a Chemist working for the MONSANTO Company in the USA. (Franz received the National medal of technology in 1987 and the Perkin Medal for Applied Chemistry in 1990 for his discoveries. He was inducted into the National Inventor's Hall of Fame in 2007). Monsanto brought Glyphosate to market in the 1970s under the trade name "Roundup", and Monsanto's last commercially relevant United States patent expired in 2000.
Experts in herbicides considered Glyphosate to be "virtually ideal" due to its broad spectrum action and low toxicity to animal life compared with other herbicides. Glyphosate was quickly adopted by farmers worldwide, and global sales of the product amounted to 650,000 tonnes in the year 2011, and these sales were worth around US$6.5 billion (more than the value of all other herbicides combined.) Glyphosate use keeps increasing, and one industry analyst predicts global glyphosate use could double by 2017. China leads the world in production of Glyphosate at present. Environmental fate
Glyphosate is strongly adsorbed (held onto) by soil and is not believed to move vertically below the six-inch soil layer; residues are expected to be immobile in soil. It is readily degraded by soil microbes and breaks down in about 50 days.
Glyphosate is not likely to move to ground water due to their strong adsorptive characteristics. However, it may reach surface water bodies through soil erosion as it adsorbs to soil particles suspended in runoff. If glyphosate reaches surface water, it would be broken down in about 90 days. Its permissible limits in the drinking water are 0.7 ppm (parts per million, or 700 parts per billion (ppb) in the US and 200 ppb in the EU).
Glyphosate has a United States Environmental Protection Agency (EPA) Toxicity Class of III (on a I to IV scale, where IV is least dangerous) for oral and inhalation exposure. Glyphosate does not bioaccumulate in mammals; it is excreted in urine and feces.
L.D. 50 (i.e. the amount needed to kill 50 % of the population of test rats) for Glyphosate is 5. 6 gm. per Kg. Alcohol has an LD 50 of 5. This makes Glyphosate less toxic than alcohol.
Glyphosate use in Sri Lanka
In 1977, the Department of Agriculture permitted use of Glyphosate for controlling weeds in non-cropped lands in the hill country and this was extended to all of Sri Lanka in 1994, again for only non-cropped lands. Use in paddy fields was permitted only in 1998.
Glyphosate began to be used by some paddy (rice) farmers as a pre plant spray applied 10-14 days before ploughing their fields because it hastened the decomposition of weeds. However, its use by paddy farmers became popular only after the banning of the much cheaper herbicide Paraquat in 2010. Paddy farmers who chose to apply Glyphosate prior to ploughing their fields, do so only once every six months. Price of Glyphosate was more than ten times that of Paraquat in the early days, and 'poor' paddy farmers could not have afforded it even if they wanted to. It was mainly used in the 'plantation sector' (Tea, Rubber and Coconut estates) to control weeds because it was cheaper than using manual labour, and labour is becoming increasingly scarce in these areas. It has a special significance for Tea Estates in the hill country since it helps in controlling soil erosion (the dead weeds acting as a protective soil cover during the rainy season). Price of Glyphosate plummeted after 2000 (when MONSANTO's patent on GLyphosate-"ROUNDUP"expired, and China began to take over as the World's largest manufacturer of Glyphosate). Tea Estates and Coconut plantations are major users of Glyphosate for weed control to this day.
CKDu and Glyphosate
The first cases of CKDu (Chronic Kidney Disease of Uncertain Etiology) were diagnosed in the North Central Province (NCP) in the mid 1990s- long before the widespread use of the herbicide Glyphosate by paddy farmers. CKDu has NOT been diagnosed in many other parts of the country (Batticaloa, Hambantota, Kalpitiya, Ampara etc) where Glyphosate is widely used, and farming practices are similar to the NCP. CKDu has NOT surfaced in the plantation sector where Glyphosate is widely used.
Jayasumana et.al ( J. Environ. Res. Public Health, 2014, 11 2125-2147) were probably the first to hypothesize that Glyphosate may be a possible factor contributing to CKDu. In a more recent article (Environ.Health 2015, 14:6) these authors conclude that, "CKDu epidemic among farmers in dry zone of Sri Lanka is associated with a history of drinking water from a well that was abandoned, and the spraying of Glyphosate and other pesticides in paddy fields".
The association of CKDu with drinking ground water from shallow dug wells is nothing new. As such, providing clean drinking water has been widely advocated by many researchers as a means of mitigating this kidney disease. However, what is it in the ground water that specifically contributes to CKDu, is still NOT known. High levels of Fluoride, Calcium and Magnesium (contributing to "hard water"), and high salt concentrations have all been found to be associated with well water, and may play some role in the development of CKDu.
The concentrations of Glyphosate in well water (().7 - 3.5 ppb) reported by Jayasumana et.al. is 200 times less than the maximum permissible contaminant level specified by the U.S. EPA ( 700 ppb.)
Considering the facts stated above, Glyphosate as a causative factor of CKDu is unlikely and highly speculative, and there is no Justification for banning Glyphosate on this score.
Glyphosate and cancer
The World Health Organisation (WHO) has recently classified Glyphosate as "probably carcinogenic to humans" based on the results of experiments conducted with rats.
The insecticides Malathion (used in Malaria mosquito control) and Diazinon fall into the same category.
Even cellular phones are classified as potentially carcinogenic, but virtually every Sri Lankan uses a cellular phone. We have over 20 million cellular phones in Sri Lanka at present, and still more are being imported into the country. Do we call for a ban on cellular phones as well? Do we risk an outbreak of Malaria by banning the import of Malathion? Even DDT - proven to be carcinogenic, and having serious environmental consequences, is now permitted for use in Malaria control in some African countries by WHO. This is because the risk of dying from Malaria far outweighs the threats to the environment, and risk of cancer. Rational decision making requires risk -benefit assessment.