By Chandre Dharmawardana –

Dr. Chandre Dharmawardana

It is gratifying that several writers have taken up  the vital topic of pesticide use in agriculture (6^th  of February, Island). Dr. Ranil Sananayake (RS)  has claimed to  “rebut”  what I wrote. I stated  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 most of 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 ecosystems of highly fertilized (HF) and traditionally farmed (TF) fields”.

Photo credit Dr. Chamila Perera

I had nowhere claimed that development is only measured by the GDP, or ever given one-parameter explanations of complex entities like  an economy or a ecosystem. 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 MIS-USE, are 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 give technical data or references to the scientific literature. It was Dr. Sarath Amarasiri, an ex-Director General of Agriculture who initially used this very apt indicator of a healthy soil in popular discussions, and I concur with him. 

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  a single cause  –  the  use of “toxic” agrochemicals  in  highly fertilized agriculture. Of course, only the colossally knowledgeable would dare to present such single-cause explanations of complex issues like ornithological or other types of 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 – be it kidney disease or  alzheimer – finds easy credence with the  populace. Hence the rise of  the likes of Ven. Ratana, Vandana Shiva in India, and similar “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 the most 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, being allegedly infallible when he speaks on matters of the faith. 

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. It is true that hosphate levels in water rise above tolerable thresholds seasonally and produce algae blooms. But 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. There are many other studies that support the same conclusion. For instance, 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 Sr 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” and suggest that these countries use less agrochemicals. World bank data for agrochemical use taken as they are confirm what Dr. W says. However, their fertilizer inputs to paddy fields are similar to those of 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 residual 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. I n addition, garbage containing plastics are regularly burnt in urban and rural locations. The ambient amounts of  toxins in the air greatly exceed  WHO specifications by factors pf thousands. Toxins from fossil-fuel exhaust have a marked effect on biodiversity, especially 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 like Ven. Ratana, and the not-so Green ones import and sell their duty-free cars on the black market!  Furthermore, politicians are pushing for the installation of coal-fired power stations which are notorious for their polluting effects as well as their capacity to fill their bank accounts with commissions.  

Loss of bird biodiversity will be reflected at every level of an 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  27^th  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 and affect them, then why aren’t  the honey bees similarly affected?

While pesticides and other secondary causes like the emergence of new types of parasites play a secondary role, 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, roads 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.

Organic farming needs two to four times land and water to obtain the same yields as with hybrid seeds using methods of modern intense agriculture etc., that require no tilling (i.e., no erosion and   less agrochemical runoff). In contrast, organic agriculture causes grater 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 implicitly verify these negatives of organic farming.

Dr. Widanapathirana emphasizes the need for effective controls  and farmer education. I fully concur with him. In fact, it is not just farmers, but also the general public who must be made aware of the safe use of agrochemicals. During my tenure as a Professor of Chemistry and a Vice-Chancellor of a Sri Lankan University in the mid-1970s, I took pains to introduce mandatory course units in environmental science to our science graduates. We also introduced, for the first time, specialized courses in food science and technology to deliver healthy food to the public.  Unfortunately this does not seem to be true of current course content in Sri Lankan B.Sc courses.    

Agrochemicals should be controlled (not banned) within a precautionary principle, almost as with pharmaceuticals. Every substance becomes a toxin – be it vitamins or even salt and pepper  –  if the recommended dose is exceeded. The same is true for soil toxicity. It is the technical officers of the Department of Agriculture (DOA) who should issue permits for releasing  optimal amounts of fertilizer and pesticide needed by each customer, depending on the local conditions and the cultivation cycle. The DOA officials can advise the farmers on crop rotation techniques etc., that can be used to reduce the needed pesticide and fertilizer inputs. 

In fact, a rudimentary control system existed prior to 1977, but  it was axed on the alter of the free market when “Mudalalis – i.e., henchmen of the local politicians – began  to sell agrochemicals for as much profit as possible, 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. DS 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.