pesticides and organophosphate poisoining.

PESTICIDAL POISONING

BYCH.SAMPATH KUMAR

PHARM D 4TH YEAR

PESTICIDES

A pesticide is a substance or mixture of substance intended for preventing, destroying, repelling or lessening the damage caused by the pest.

A pesticide can be a insect, plant pathogen, weed, bacteria, bird etc. That compete with the

human for food, destroy property, spread disease. A pesticide can be a chemical, biological agent, antimicrobial,

disinfectant etc. Many chemical pesticides are poisonous to

human and animals.

PESTICIDES

Classification of pesticides1. Herbicide-These are the chemicals used to kill weeds

(i.e., unwanted plants) e.g. paraquat,diquat2. Insecticide-These are used to kill insects. E.g.

orghanophosphates,carbamates,pyrethroids.3. Rodenticide-These are used to kill rodents. e.g.

anticoagulants,zinc,phosphorous4. Nematicide-These are used to kill nematodes(worms)

e.g. ethylene dibromide5. Molluscicide-These ar used to kill molluscs such as

snails &slugs e.g metaldehyde

6.Fungicides-These are used to kill fungus e.g. captan,sodium azide

7.Acaricides :compounds which kill mites,ticks &spiders

e.g. Azobenzene,chlorbenzilate

8.Miscellaneous pesticides: Hydrogen cyanide

Possible Health Effects

• Endocrine Damage- thyroid, hormonal, reproductive, and metabolism

• Cancers• Nervous System Damage• Liver Damage• Irritation to Skin and Eyes• Vomiting, diarrhea, slow heart rate• Birth DefectsMost health risks are associated with farm workers or improper use although many studies have been done that support endocrine damage to children from exposure to pesticides in food.

How do Pesticides Affect the Environment?

• Approx. 67 million birds die each year from pesticides in the air

• Hundreds of fish die each year due to pesticide run-offs in the water

• Pesticides can……..• Kill wildlife due to posing• Cause reproductive, developmental, and

behavioral problems

Facts About Pesticides

• At least three million people are poisoned by pesticides every year.

• 25 million agricultural workers are poisoned every year.

• More than 200,000 people die each year from pesticides

• Half of all pesticides are used on the five main crops- cereals, corn/maize, rice, cotton and soya.

ORGANOPHOSPHATE POISONING

Introduction:• Organophosphate (OP) compounds are a diverse group of

chemicals used in both domestic and industrial settings. • Examples of organophosphates include insecticides

(malathion, parathion, dichlorvos, and diazinon)• Worldwide mortality studies report mortality rates from 3-

25 %• Mortality rates depend on the type of compound used,

amount ingested, general health of the patient, delay in discovery and transport, insufficient respiratory management, delay in intubation, and failure in weaning off ventilatory support.

Organophosphate(insecticide) organophosphate poisoning accounts for nearly one third of hospital admissions from poisoning in Sri Lanka.Commonly using trades are follows.Malathion, parathion, diazinon, fenthione, chlorpyrifos.

Actioninhibit acetylcholine esterase enzymeat nerve endings by phosphorylation acetylcholine at receptor sites

clinical features depends on route of entry

ingestion inhalation eye contact

Route of entry:

Inhalation

• Cough• Difficulty in breathing• Bronchitis• Pneumonia

Eye contact

• Irritation• Pain• Lacrimation• Miosis• Blurring vision• Photophobia

Mnemonic for muscarinic signs & symptoms:

• S – Salivation D – Diaphoresis & diarrhoea

• L- Lacrimation U - Urination• U – Urinary incontinence M - Miosis• D – Diarrhoea + diaphoresis B – Bradycardia,

bronchospasm• G – GI upset E – Excess • E –Emesis L – Lacrimation & S - Salivation

CLINICAL FEATURES-Muscarinic Nicotinic Central receptors

Cardiovascular Bradycardia Hypotension Respiratory Rhinorrhea Bronchorrhea/spasm Cough Gastrointestinal Increased salivation Nausea/vomiting Abdominal pain Diarrhoea Fecal incontinence Genitourinary Urinary incontinence Ocular Blurred vision/miosis Increased lacrimation

Cardiovascular Tachycardia Hypertension Musculoskeletal Weakness Fasciculations Cramps Paralysis

Anxiety Restlessness Ataxia Convulsions Insomnia Dysarthria Tremors Coma Absent reflexes CS respiration Resp. depression Circulatory collapse

GASTRIC LAVAGE ACTIVATED CHARCOAL

OROPHARYNGEAL AIRWAY USED AMBU VENTILATION & ET TUBE

Investigations

ECGOxygen saturationBlood gas analysisRenal and hepatic functionElectrolytesGlucoseAmylaseUrine toxicology

Grading of severity of poisoning

Biochemical Grading:Red cell cholinesterase activity (% normal)

Grade• 20-50% Mild• 10-20%

Moderate• <10%

Severe

Management of OP Poisoning

Hospitalization/ ICU1. Initial stabilization2. Reduction of exposure3. Administration of specific

antidote4. Supportive treatment

Management-ABCD

• Airway - ensure clear airway, clear secretions, check for cough/gag

• Breathing - check oxygenation, supplemental O2, breathing pattern & adequacy

• Circulation - heart rate, rhythm, blood pressure

• Decontamination – gut and skin

Initial Stabilization of the patient

• Clear airway and • Adequate ventilation because the

patient with acute organophosphate poisoning (ACC) commonly presents with respiratory distress.

• Oxygen- Circulation- iv access

Decontamination• Dermal spills—wash pesticide spills from the

patientwith soap and water and remove and discard contaminated clothes, shoes and any other material made from leather

• Gastric lavage—consider for presentations within 1 or 2 hours, when the airway is protected. A single aspiration of the gastric contents may be as useful as lavage

• Activated charcoal —50 g may be given orally or nasogastrically to patients who are cooperative or intubated, particularly if they are admitted within one or two hours or have severe toxicity

Antidotes in the treatment of OP poisoning

• Atropine- Reverses the muscarinic features.

• Oxime- Reactivate cholinesterase and reverses the nicotinic features.

Atropine

• Initial dose: 0.5-2 mg IV every 5-10min until atropinization

• Continuous infusion (8mg atropine in 100ml NS) at rate of 0.02-0.08mg/kg/hr (0.25-1.0 ml/kg/hr) with additional 1-5mg bolus

• May require about 40-1500mg/day• For at least 5-7days• Watch out for OVER ATROPINIZATION

Pralidoxime• An oxime that reactivates phosphorylated cholinesterase• Effects: skeletal-neuromuscular junctions (counteracts

weakness, fasciculation and respiratory depression)• Administration within 48 hours of poison ingestion• IV 1-2gm in 100cc of NS over 30min (at a rate not exceeding

200mg/min), repeat in 1 hour if muscle weakness persist, then at 8-12 hours interval if cholinergic signs recur

• Severe case: IV infusion 500mg/hr (max 12gm in 24hours)• Started after maximal atropinization

OXIMES IN OP POISONING

Other Treatments under investigation• Magnesium

• Reduces acetylcholine release• Blockage pre-synaptic calcium channels• Limited human studies

• Clonidine• Decrease the presynaptic synthesis and release of

acetylcholine. • Central nervous system > peripheral cholinergic synapses

• Diazepam• Diazepam reduces respiratory failure and cognitive deficit • Postulate “uncoordinated stimulation of the respiratory

centres decreases phrenic nerve output”.

Thank you