With the increasing popularity of horticulture and home gardening in particular, the use of pesticides has become common and widespread in Sri Lanka. This is especially so with the orchid growers and floriculturists whose numbers have increased greatly in the past couple of decades.
It is common practice, particularly among orchid growers, to use various combinations of insecticides, fungicides and different combinations of fertilizers in order to achieve successful results.
Unfortunately, however, not many users of these poisons are fully aware of the hazards involved in frequent exposure despite the efforts by many institutions such as the Ministry of Agriculture, environmental groups and sometimes by the media. Yet, there seem to be many users of these poisons who believe that ‘it cannot affect me’. But major injuries or deaths have been reported on exposure to some of these chemicals. In fact, 1242 deaths were recorded in 2006 in Sri Lanka due to pesticide poisoning. In the same year, 2787 deaths occurred due to suicide using pesticides.
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With the various insect vectors and disease pathogens becoming resistant to traditional pesticides, newer and more potent pesticides are being introduced to the market. Some of these are claimed to be of low mammalian toxicity but one cannot dismiss the fact that misuse can cause at least some harm to the user. It has been reported that about 70 per cent use more than the stipulated dosage and over 80 percent had symptoms of intense toxicity following spraying. It is possible that a bad headache, a spell of dizziness, an unaccountable incidence of fatigue or even a digestive upset could be as a result of exposure.
But, on the other hand, how is the average user to know about the relative safety or the toxicity of the sea of chemicals that he is being advised to use by the vendors? On the side of the regulators, the Control of Pesticides Act No. 33 of 1980 makes provisions to regulate the import, formulation, packing, labelling, storage, transport, sale and use of pesticides.
As far as the average user is concerned, the most important way of reckoning the relative toxicity is by studying the LD50 value of a product. LD means lethal dose (deadly amount) and the subscript 50 means that the dose was acutely lethal to 50% of the animals to whom the chemical was administered under controlled laboratory conditions.
Of the two commonly used LD50 values, the oral and the dermal, the latter provides more relevant information on hazards encountered by those occupationally exposed.
Oral exposure may occur because of an accident, but is more likely to occur as the result of carelessness, such as blowing out a plugged nozzle with your mouth, smoking or eating without washing your hands after using a pesticide, splashing concentrate while mixing, or eating produce that has been recently sprayed.
Dermal (skin) exposure accounts for about 90% of the exposure pesticide users receive from non fumigant pesticides. It may occur any time a pesticide is mixed, applied, or handled, and it often goes undetected. Dry materials, dust, wettable powders, and granules, as well as liquid pesticides can be absorbed through the skin.
It has been found out that the rate of dermal absorption by different areas of the human body varies greatly. In typical work situations, skin absorption is the most common route of poisoning from pesticides. Absorption will continue as long as the pesticide remains in contact with the skin. Certain areas of the body such as the genital area and eyes absorb pesticides easily and rapidly.
It is easy to transfer pesticide residues from one part of the body to another. For example, residues can be inadvertently moved from a hand to a sweaty forehead (4.2) or to the genital area (11.8).
Users must always be aware of the dangers they can be exposed to.
Things to remember when spraying
It is essential that one wears protective clothing, goggles, gloves and suitable masks when spraying any type of agrochemical. It is also important that the user takes a bath using soap and copious amounts of water immediately after a spray session. The clothes used should also be washed after each use as accumulation spray or dust can become quite toxic. Take special care when spraying in areas of low air movement such as centre courtyards, polytunnels or greenhouses where the dust or the spray mist has a tendency to “hang on” for longer periods than in open air.
- When spraying, do not work in a mist or drift of the spray. Be mindful of the air currents and always stay downwind.
- Do not suck or blow a clogged nozzle or tube or chew betel, or smoke while spraying or touch foodstuffs before washing your hands.
- If any sickness occurs as a result of spraying or exposure, immediately consult a doctor and do not fail to mention the name or take the bottle of pesticide along.
- Keep all chemicals out of reach children and securely locked up at all times. Always have the container labels intact and strictly adhere to the instructions in order to avoid danger to persons as well as plants.
- Dispose of the empty containers so as to avoid collection by “bottle collectors” and street urchins. The last few drops of chemical remaining in a bottle can be deadly in the hands of an unsuspecting child.
- Do not throw remains or empty containers of any poisonous substance into rivers, lakes or ponds. Make sure that these remains can be washed away by water running on the surface. Pour them to a hole in the ground away from wells, springs etc., if possible in a low lying area.
- Finally remember that pesticides are designed to control pests, but they can also be toxic (poisonous) to plants and animals, including humans. Always keep in mind “pesticides are dangerous and must be handled with care.”
(The writer is the Vice-President/Hony. Editor of the Horticultural & Flora Conservation Society-Sri Lanka) |
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