Safe agrochemical use


It is gratifying that several writers have taken up the vital topic of pesticide use in agriculture (6thof February, Island). Dr. Ranil Senanayake (RS) has claimed to "rebut" what I wrote – i.e., that our soils are NOT laden with toxic agrochemicals, and that they support a thriving ecosystem full of bugs and worms. They attract egrets and other birds when the soil is tilled. I claimed that the crops from our soils are safe to eat. RS seems to hold that our soils are full of toxic agrochemical residues that have harmed biodiversity. Dr. Anura Widanapathirana (AW) has called for 'proper controls on pesticide use' and I agree with his views.

RS says "There are only Egrets left (and sometime a few Ibis), these are the most resistant to toxins in the chemically changed paddy fields we have today....The earthworms and bugs ... are again only those species with a high degree of tolerance, the rest have disappeared". He proceeds to a personal categorization of me as carrying on "some narrow minded personal vendetta against, other Sri Lankans (misguided or not) to bolster ... the economically utilitarian view of the world .... In this, he shares the stage with ... politicians and bureaucrats who believe that development is only measured by the GDP. Public health ... is of little consequence". Surely, Dr. RS is unaware that our politicians believe only in aggrandizing their own pockets and not the GDP! He accuses me "of colossal ignorance ... in ornithological history and confusion with the soil ecosystem highly fertilized (HF) and traditionally farmed (TF) fields".

I had nowhere claimed that development is only measured by the GDP, or ever given one-parameter explanations of complex entities like an economic system. I was NOT comparing HF systems and TF fields. The main concern was whether the HF soil is full of harmful agrochemical toxins or not, and my answer has been that field studies have shown that the toxin levels, even after several decades of agrochemical use and indeed MISUSE, is well below the maximum tolerable levels (MTL) set by the WHO and the FAO.

In answering Mr. Siri Pathirana, who identifies himself as a simple farmer, it seemed better to use the flocking of birds to paddy fields rather than technical data. Dr. Sarath Amarasiri, an ex-Director General of Agriculture, has also used this very apt indicator of a healthy soil in popular discussions.

Dr. RS, after accusing me of "colossal ignorance of ornithological history", proceeds to show his colossal knowledge of the subject by essentially claiming that the loss of biodiversity is caused by the use of "toxic" agrochemicals in highly fertilized agriculture. Of course, only the colossally knowledgeable would dare to present such one-cause explanations of complex issues like ornithological or other biodiversity. However, just as the simplified five-lesson political analysis of the early JVP was very attractive to many members of the public, the simplistic theory that agrochemicals are THE cause of loss of biodiversity and most health problems finds easy credence with the populace. Hence the rise of the likes of Ven. Ratana, Vandana Shiva in India, and "Green champions" in many countries, claiming that we must return to "natural" agriculture; some even reject vaccinations, immunizations, fluoridation of water, and other public health initiatives.

How can Dr. RS say that earthworms and egrets are hardy against agro-toxins? He should give a quantitative criterion (e.g., the LP50 values/weight) before he rushes to print. Only the Pope can make unsubstantiated ex-cathedra statements.

The earthworm is a most sensitive creature widely used by scientists as a barometer of soil health. At a more microscopic level, the total micro-organism biomass, as well as, say, the distribution of the mass spectrum of the micro-organisms can be used as measures of the health of the soil. If we consider a widely used agrochemical like glyphosate, numerous studies show how earthworms become healthier when the naturally or industrially occurring soil cadmium and other trace heavy metals are made insoluble by the glyphosate residues that reach the soil during spraying. For a recent study, see: Zhou et al, Environmental Toxicology and Chemistry, vol. 33, p 2351-2357 (2014). Similarly, regarding the effect of glyphosate formulations on soil microbes and microbial community structure, see: Lane et al, Pedobiologia, vol. 55, pages 325-342 (2012).

Dr. Widanapathirana also makes anecdotal claims of loss of biodiversity, e.g., that there are fewer leeches, both on land and in water. However, is this predominantly caused by agrochemicals? Dr. W does not say that harmful levels of pesticides are found in the Sri Lankan environments. While phosphate levels in water rises above thresholds seasonally, there is ample evidence that the ambient pesticide-residue levels remain well below the tolerable maxima. The WHO-NSF study on Chronic Kidney disease examined the pesticide levels and metal toxins in the North Central Province (Jayatilleke et al 2014) and found amounts well below WHO specifications. The study reported by Aravinna et al. [Journal of Environmental Science and Health, Part B, vol. 52, p. 37–47. (2016)] confirms the lack of significant amounts of pesticide residues in Sri Lanka's environment. The WHO thresholds are set, mindful of bio-magnification of pesticide residues on plant uptake.

Dr. Widanapathirana says that "In contrast, the paddy fields in Myanmar, Laos and Cambodia are full of fish and other edible creatures". World Bank data for agrochemical use show that these countries use fertilizer inputs similar to Sri Lanka, when the very high usage in tea estates is factored out. But there is no doubt that, optimally, much less fertilizer would be used if the free market in agrochemicals is abolished.

So, while the pesticide load is low, Sri Lanka's environment, both rural and urban, is full of partially oxidized petroleum, kerosene and diesel residues, with vast amounts of highly toxic particulate matter. The ambient amounts greatly exceed WHO specifications. Toxins from fossil-fuel exhaust has a marked effect on biodiversity, and as they occur at levels above thresholds. But those who wish to ban agrochemicals and wax eloquent about traditional farming remain mum about adopting traditional transport. "Green" politicians import and sell their duty-free cars on the black market!

Loss of bird biodiversity will be reflected at every level of ecology, be it butterflies, bees, earthworms, earwigs or amoebas. It is common to find e-mail messages from the so-called "AVAAZ team" soliciting donations to fight agribusiness, claiming that bees all over the world are decimated by agrochemicals. This is similar to Dr. Senanayake directly equating the loss of bird biodiversity to toxic agrochemicals. Interestingly, contrary to the claim of the AVAAZ team, the populations of bees have increased by 40% according to Prof. David Goulson of Oxford University and collaborators (Science 27th Mar 2015: Vol. 347, page 1255957). What has been decreasing rather dramatically are the WILD BEES. If some whiffs of the spray of neonicotinoids are claimed to spread even to the wild bees, then why aren’t the honey bees affected?

The main reason for the decline of wild bees, butterflies, leeches etc., and indeed the decline of biodiversity in general is the LOSS OF WILDERNESS HABITAT. Human encroachment, be it for housing or organic farming, destroys habitat. The destruction of habitat for human use since independence in Sri Lanka has been truly extensive, given a population increase of a factor of four. Biodiversity has been the victim. However, adopting organic farming makes matters worse (see:

Organic farming needs two to four times land and water to obtain the same yields as with hybrid seeds, methods of modern intense agriculture etc., that require no tilling (i.e., no erosion and less agrochemical runoff). In contrast, organic agriculture causes greater habitat loss and erosion. The research report by high-priests of organic farming, headed by Dr. Adrian Mueller of the Swiss institute of Organic agriculture verify these negatives of organic farming (For further details, see:

Dr. Widanapathirana emphasizes the need for effective controls and farmer education. I fully concur with him. Agrochemicals should be controlled (not banned) within a precautionary principle, almost as with pharmaceuticals. It is the technical officers of the Department of Agriculture who should issue permits for releasing optimal amounts of fertilizer and pesticide needed by each customer, depending on the local conditions. In fact, a rudimentary control system existed prior to 1977, but axed on the altar of the free market when "Mudalalis – i.e., henchmen of the local politicians – began to sell agrochemicals together with other general merchandise.

Dr Ranil Senanayake quotes Hon. DS Senanayake, a great agriculturist and Prime Minister who pushed forward modern farming, modern irrigation, and unhesitatingly used DDT to combat malaria. Hon. D.S. Senanayake had said that ‘Development of our nation should be measured by the larder of the poorest of its homes’. Indeed, if RS expects the poorest of the land to stock their larders with organic rice at 5-10 times the price of normal rice, and with bottles of "spring" water (in a plastic bottle to boot !), then he does not realize that some 40% of our school children come to school hungry.




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