PESTICIDES

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PESTICIDES
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FAO( 1986 ) defines Pesticides

• Any substances or mixture of substances intended
  for preventing, destroying, or controlling any
  pest, including vectors of human or animal
  diseases, unwanted species of plant or animals
  causing harm during or otherwise interfering with
  the production,processing,storage,transport or
  marketing of food, agricultural commodities, wood
  and wood products, or animal feedstuffs, or which
  may be administered to animals for the control of
  insects, arachnids, or other pests in or on the
  bodies.

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WHY USE PESTICIDES ?

• Prevent damages pre post-harvest
• To improve quantity and quality of food fibre
• Prevent or control communicable diseases.
• Good business .in underdevelop developing
  countries

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PESTICIDES

• DEFINITION
• Group of chemicals intended to destroy or control
  pests of all kinds
• INSECTICIDES Destroy insects
• HERBICIDES Destroy plants
• FUNGICIDES Destroy fungi
• LARVICIDES Destroy larvae
• NEMATICIDES Destroy nematodes

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PESTICIDES COMMON CHEMICAL GROUPS

• Organo chlorines DDT, dieldrin, heptachlor
• Organo phosphate Malathion
• Carbamates propoxur, methiocarb
• Synth. pyrethroids permethrin,
  cypermethrin
• Bipyridilium Paraquat, diquat
• Phenoxyacetates 2,4-D 2,4,5-T
• Triazine simazine
• Organic mercuric compound

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Routes of exposure

• Oral
• uncommon
• mostly accidental
• Dermal
• Liquids, some powders gases
• leads to systemic poisoning
• Inhalation
• gases, vapours, droplets dusts
• reaches tissues via bloodstream

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Hazards to health

• Toxicity
• Physico-chemical properties
• Formulations ( liquid vs granules,solvents)
• Concentrations

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Risk to health

• Method of application
• Exposure ( concentration, time )
• Route of exposure
• Environmental conditions

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HEALTH EFFECTS

• Acute exposure
• Varies among the pesticides families
• Vast majority of acute poisoning -
  Organophosphate - Carbamates
• Diagnosis of acute poisoning
• Sign Symptoms
• Temporal relationship to known exposure
• Evidence of poisoning in other workers / family

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Chronic effects
HEALTH EFFECTS

• Dermatologic
• 1/3 of pesticides reported diseases
• Skin irritant to skin sensitizer
• Cancer
• Human carcinogen- controversies
• Epidermiology studies animal experiment
• Reproductive
• Not recognised as human teratogen
• Reported cases are available and animal studies

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HEALTH EFFECTSOrganochlorines eg DDT

• Exposure all three routes
• Slowly excreted
• Accumulate in body
• Affect nervous system
• Symptoms
• Excitement,anxiety,twitching,convulsion death.
• Most now controlled or banned

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HEALTH EFFECTSOrganophosphate eg Malathion

• Widely used- WW II
• Individually vary widely in toxicity
• Do not accumulate in body
• Affects nervous system ( cholinesterase )
• Symptoms
• Weakness, vomiting, cold sweating, abdominal
  cramps, twitching, convulsions death

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HEALTH EFFECTSCarbamates

• Similar to organo-phosphates
• Effects wear off quicker

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HEALTH EFFECTSPyrethrin Synthetic Pyrethroids

• Increasingly popular
• Pyrethrum - partially refine extract of
  Chrysanthemum
• Seldom causes serious harm
• Symptoms
• Acute Not known
• Chronic Allergic contact dermatitis Facial
  pains, skin rash, reddening, some cause
  convulsions.

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HEALTH EFFECTSBipyrilidium Compound

• Important members, Paraquat, diquat
• Paraquat medically most important
• Contact to skin,eyes respiratory tract
• Irritations of skin, crack discoloration of
  fingernails, conjunctivitis, sorethroat
• Ingestion
• Early Oral abdo pain, nausea, vomiting
  diarrhea
• Later Liver injury, renal injury
• Late Pulmonary fibrosis
• Lethal if relatively small quantity swallowed -
  addition of emetic

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CONTROL MEASURES

• ELIMINATE
• Physical alternatives
• SUBSTITUTE
• Less toxic
• Safer physical form
• ISOLATE
• Enclose operator ( eg Cabs )
• ENCLOSE
• Use chambers ( fumigants )

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CONTROL MEASURES

• ENGINEERING CONTROLS
• Increase droplet size of spray
• Low pressure applications
• Ventilations, bunding ,impervious floor secure
  - storage areas
• PROTECTIVE EQUIPMENTS
• Skin Protection
• Respiratory Protection
• Eye Protection

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CONTROL MEASURES

• HYGIENE FACILITIES
• Washing / Shower
• Clean clothing
• Laundry
• MEDICAL SURVEILLANCE
• Medical examination
• Biological monitoring ( eg Cholinesterase )

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DISPOSAL

• More critical
• Container still harbouring trace of pesticides
• To prevent harm to animal,human environment

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DISPOSAL GUIDELINES

• Return left-over concentrates to the supplier
• Rinse container should be rinsed 2-3 times but
  avoid polluting the public sewers, water courses,
  wells, springs etc.
• Best methods of disposal- supplier to collect
  empty containers
• Buried in isolated and identifiable site at least
  450mm deep or burned if combustible.
• If in doubt seek advice from manufacturer or the
  relevant authorities.

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THE END

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