Proceedings of the Asia regional workshop on the

edible part <strong>of</strong> crops and <strong>the</strong> daily consumption <strong>of</strong> crops. Although, persistent products are screened
out during registration and pre-harvest intervals are given accordingly for <strong>the</strong> recommended crops in
<strong>the</strong> label, <strong>the</strong> common farmer practice <strong>of</strong> applying pesticides close to harvest and sometimes even
after harvesting for protection during transport and marketing do raise concerns <strong>of</strong> high levels <strong>of</strong>
residues in foods.
There are no comprehensive studies done in <strong>the</strong> recent past to assess <strong>the</strong> residue levels in
vegetables and fruits. Although, organochlorine insecticides such as aldrin, DDT, dieldrin, endrin,
HCH, heptachlor, and lindane have been phased-out from use in Sri Lanka, at least since two decades
ago, <strong>the</strong>ir residues may still remain in <strong>the</strong> environment. A survey <strong>of</strong> organochlorine insecticide
residues conducted in 1979 has revealed traces <strong>of</strong> residues in vegetables as well as in soil and water.
As some <strong>of</strong> those chemicals are potential carcinogens, presence <strong>of</strong> traces in <strong>the</strong> environment poses
serious threat to human health. However, a limited study conducted by <strong>the</strong> Office <strong>of</strong> <strong>the</strong> Registrar <strong>of</strong>
Pesticides in 2000 for few vegetable and fruit samples collected from <strong>the</strong> market (imported fruits
such as grapes and pear samples with known origin obtained at <strong>the</strong> entry <strong>of</strong> point were also included)
confirmed that <strong>the</strong> residues in tested samples contained within <strong>the</strong> acceptable levels for pesticides
which included organophosphates, carbamates, organochlorines and carcinogens.
Unfortunately, <strong>the</strong>re is no program currently in place in <strong>the</strong> country to conduct continuous
monitoring <strong>of</strong> residues, due to lack <strong>of</strong> required laboratory facilities. Regulatory authorities have <strong>the</strong>
necessary mandates for establishment <strong>of</strong> Maximum Residue Limits (MRL) for crops with respect to
pesticides registered in <strong>the</strong> country. It enables to determine <strong>the</strong> Pre-Harvest Intervals (PHI) for
pesticides given in <strong>the</strong> label for <strong>the</strong> farmers to follow, thus maintaining residue in acceptable levels.
These vital parameters have to be developed under local conditions as <strong>the</strong> behavior <strong>of</strong> pesticides in
<strong>the</strong> environment is greatly dependent on local environmental conditions and human intake <strong>of</strong> such
residues fur<strong>the</strong>r depended upon <strong>the</strong> cooking and eating habits <strong>of</strong> <strong>the</strong> society.
Toxic by-products and impurities
Apart from <strong>the</strong> inherent toxicity <strong>of</strong> pesticidal substances, <strong>the</strong> hazard <strong>of</strong> <strong>the</strong> final marketed
product is greatly dependent upon <strong>the</strong> impurities as well as nature and quality <strong>of</strong> <strong>the</strong> o<strong>the</strong>r ingredients
incorporated in <strong>the</strong> preparation. In spite <strong>of</strong> assurance <strong>of</strong> quality through registration procedure,
which mainly focuses on <strong>the</strong> literature <strong>of</strong> <strong>the</strong> product, <strong>the</strong>re were number <strong>of</strong> occasions where inferior
quality has been reported in products <strong>of</strong>fered to <strong>the</strong> farmer. It is believed that a large number <strong>of</strong> such
incidents are not reported due to lack <strong>of</strong> proper investigation and recording system in every related
discipline. Ethylene thiourea (ETU), an impurity in one <strong>of</strong> <strong>the</strong> most extensively used class <strong>of</strong>
fungicides, is a potential carcinogen. Under careful controlled manufacturing procedures, <strong>the</strong> level
<strong>of</strong> this very dangerous substance can be maintained below <strong>the</strong> harmful level. Since this class <strong>of</strong>
fungicides has become a commodity in <strong>the</strong> international market, <strong>the</strong>re are number <strong>of</strong> manufacturers
and some may not be capable <strong>of</strong> always confirming to <strong>the</strong> required standards. There are several
similar situations exist in this field. Thus, it is vital that routing testing <strong>of</strong> quality standards is carried
out by <strong>the</strong> regulatory authorities for such products to ensure <strong>the</strong> safety.
Ano<strong>the</strong>r field survey conducted by <strong>the</strong> Office <strong>of</strong> <strong>the</strong> Registrar <strong>of</strong> Pesticides in collaboration
with <strong>the</strong> University <strong>of</strong> Pr<strong>of</strong>essional Education, Ne<strong>the</strong>rlands reports that a large extent <strong>of</strong> land has
been abandoned at Matale as vegetables are not grown any longer due to extensive use <strong>of</strong> pesticides
and fertilizer in <strong>the</strong> past. The real environmental impact has yet to be properly studied. A survey on
impact <strong>of</strong> agriculture on ground water quality carried out at Kalpitiya peninsula, where onion is
cultivated extensively has revealed significant levels <strong>of</strong> carb<strong>of</strong>uran and very high levels <strong>of</strong> nitrate
fertilizer in ground water.
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