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TOXICOLOGY OF AGROCHEMICALS
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Pesticides are one of the most widely used agrochemicals of toxicological importance.
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With the advent of green revolution, the use of pesticides has increased many folds.
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Some of the pesticides are also used extensively as acaricides / ectoparasiticides in veterinary medicine to control insect pests of both the animals and birds.
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In addition, pesticides are also widely used to control insect vectors of public health importance.
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The United States Environmental Protection Agency (USEPA) defines pesticide as “any substance or mixture of substance intended for preventing, destroying, repelling or mitigating any pest”.
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In other words, pesticides are any chemical, physical or biological agents that would kill or destroy unwanted plant or animal pests.
On the basis of their chemical nature, insecticides may be further categorized as:
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Organochlorine or chlorinated hydrocarbon insecticides : (e.g.) DDT, endrin, heptachlor etc.
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Organophosphorus insecticides : (e.g.) Parathion, Sumithion, Malathion etc.
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Carbamate insecticides : (e.g.) Carbaryl, aldicarb etc.
Herbicides or weedicides
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Herbicides/weedicides are agents which are used to destroy undesirable plants/weeds. (e.g) dinitro compounds, phenoxoyacetic acid (2,4-D, 2,4,5,-T), Dhloroalipathic acids (Dalapon), triazenes (Atrazine, simazine) bipyridinium compounds (paraquat, diquat), substituted ureas (monouron, diuron, isoprotuon) and substituted dinitroaniline compounds (pendimethalin).
Rodenticies
Common sources of pesticide poisoning
The major sources of pesticide – poisoning are :
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Accidental exposure
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Accidental exposure is the most common source of pesticide poisoning and can result from.
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Ingestion of pesticide sprayed crops, drinking of water from paddy fields treated with pesticide may cause death of livestock. Similarly, animals may get poisoned following ingestion of paddy straw or other fodders sprayed with insecticides. Such fatalities have been most frequently encountered with endrin.
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Ingestion of contaminated concentrates particularly when the pesticide sprayed grains unfit for human consumption are used in the formulation of livestock concentrate feeds.
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Feeding or watering of animals in insecticide contaminated containers.
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Contamination of fodder or concentrates due to improper disposal of empty insecticide containers.
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Spraying of walls and interior of animal house / stores with insecticides. There is danger of licking the walls and pillars by the animals.
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Improper storage (e.g.) keeping the insecticide in the animal house within the reach of the animals or in stores where animal feeds are also stored.
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Contamination of pastures during aerial spraying of insecticides on the field crops.
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Contamination of ponds, lakes, rivers etc. due to aerial spray of insecticides or discharges of effluents from the pesticide industries to nearby water reservoirs.
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Intentional exposure
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Residues of pesticides in agricultural produce (e.g.) grains, pulses, vegetables, fruits etc.
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Residues of insecticides in animal products like meat, milk and eggs.
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Consumption of insecticide for committing suicide in human beings.
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Occupational exposure
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