PESTICIDE PESTICIDE POISONINGPOISONINGPESTICIDE PESTICIDE POISONINGPOISONINGShiromini NissankaShiromini Nissanka

Research OfficerResearch OfficerNational Poisons and Drug National Poisons and Drug

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WHAT IS A TOXIC SUBSTANCE ?

• Any substance which is harmful to the environment and humans. There are naturally occurring toxins and synthetic toxins.

Toxic SubstanceNatural Toxins Synthetic Toxins

Poisonous plants Pesticides Snakes Industrial chemicals Other poisonous animals Household products

WHAT IS A PESTICIDE ?

• A Pesticide is a chemical use to prevent, destroy or repel pests. Pests can be Insects, Mice, Weeds, Fungi or Microorganisms such as Bacteria and Viruses.

• Pesticides - Insecticides Weedicides

Rodenticides Fungicides

INSECTICIDES

• Organophosphates - Baytex EC 50,

Harcros Demro

• Carbamates - Baygon Fly Bait

• Organochlorine - Aldrin

• Pyrethroids - Baygon mosquito coil

WEEDICIDES

•Paraquat - Gramoxone•Propanil - 3 4 DPA•Glyphosate - Roundup•Chlorophenoxy - MCPA

RODENTICIDES & FUNGICIDES

• Zinc phosphide - Run rat• Coumarins - Racumin• Brodifacoum - Klerat

Pellets

Sulphur - Morisal WP, • Dithiocarbamate - Metaxil

TYPE & ROUTE OF POISONING

•Accidental Oral •Suicidal Inhalation•Homicidal Dermal•Occupational Eye contact

ORGANOPHOSPHATES AND CARBAMATES

• Group of chemicals share a common mechanism of cholinesterase inhibition and hence can cause similar symptoms.– Phosphorylation of the acetylcholinesterase (AChE)

at nerve endings.– Loss of available AChE results accumulation of

acetylcholine at receptor sites and effector organ to become over stimulated by the excess acetylcholine.

ORGANOPHOSPHATES AND CARBAMATES

Contd.•Clinical Features are based on

excessive cholinergic stimulation. Unlike organophosphate poisoning, carbamate poisoning tend to be of shorter duration because the inhibition of nerve tissue AChE is reversible.

CLINICAL FEATURES• Eye contact: Irritation or pain,

lacrymation, swelling, blurring of vision.• Inhalation: Cough, difficulty in

breathing, bronchitis, pneumonia.• Ingestion: Nausea, vomiting,

diarrhoea, sweating, salivation, small or pin point pupils, muscle twitching, fasciculation.

ORGANOCHLORINES• Very few organochlorines are used now as

pesticides. Organochlorines are very toxic if ingested or inhaled. Some are readily absorbed through the intact skin.

• Skin contact: Dermatitis• Inhalation: Inhalation can give rise to

irritation of eyes, nose, throat and cough.• Ingestion: Nausea, vomiting, diarrhoea,

abdominal pain, headache, dizziness, convulsions and coma.

PYRETHRINS & PYRETHROIDS

• Pyrethrum is an insecticide extracted from chrysanthemum flower. Active ingredients of pyrethrum are known as pyrethrins. Synthetic compounds structurally related to pyrethrins are known as pyrethroids.

• Inhalation: Allergic manifestations such as wheezing.

PYRETHRINS & PYRETHROIDS Contd…

• Ingestion: After ingestion pyrethrums have low toxicity, vomiting, epigastric pain and diarrhoea are the common features.

• Eye contact: Lacrymation, oedema of the eyelids.

• Skin contact: Allergic dermatitis.

PARAQUAT• Paraquat is a widely used herbicide in Sri Lanka.

It is a safe herbicide because it is inactivated by contact with soil. Paraquat is commonly used as suicidal poison in this country.

• Paraquat has life threatening effects on the gastrointestinal tract, kidney, liver and other organs. The lung is the primary target organ of paraquat poisoning.

PARAQUAT Contd…• Recently a new paraquat formulation with

INTEON technology (containing an alginate that converts to a gel under stomach acid conditions, increased levels of emetic and purgative) was developed in order to reduce oral toxicity. However ingestion of INTEON is still very likely to be lethal.

• Skin contact: prolonged contact will produce blistering, abrasion and ulceration. Although absorption across intact skin is slow, abraded or eroded skin allows efficient absorption.

PROPANIL & CHLOROPHENOXY

COMPOUNDS• Propanil is a selective herbicide of low

toxicity. However, in self poisoning with large doses methaemogloninaemia is cause, which can be fatal.

• Chlorophenoxy compounds are well absorbed from the gastrointestinal tract. They are less well absorbed from the lung. Cutaneous absorption appears to be minimal.

GLYPHOSATE• Glyphosate is a non-selective herbicide,

typically marketed as an aqueous solution of 41% isopropylamine glyphosate, 15% polyoxyethyleneamine surfactant and various minor components including anti-foaming and colour agents, biocides and inorganic ions to produce pH adjustment.

• Ingestion of concentrated formulations may cause epigastric pain, dysphagia, nausea, vomiting, oral ulceration, diarrhoea and haemetemesis in severe cases leading to hypovolaemic shock.

RODENTICIDES• Coumarins, indandiones and

brodifacoum are used as rodenticides. They are fairly safe for human beings due to the low concentration of the active ingredient. Their toxicity is due to depression of the synthesis of factors essential for coagulation of blood.

BANNED PESTICIDES• 1970 – Endrin• 1976 – DDT• 1980 – Chlordimeform• 1980 – Dieldrin• 1980 – Phosphamidon• 1980 – Thallium sulpht.• 1984 – 2,4,5-T• 1984 – Ethyl parathion• 1984 – Methyl parathion• 1986 - Aldrin

• 1986 – Lindane• 1987 – HCH (mixed

Isomers)• 1987 – Mercury cpds.• 1988 – Arsenic (arsenites

and arsenates)• 1988 – Hepatachlor• 1989 – Leptophos

Captafol• 1990 –Dichloropropane

BANNED PESTICIDES Contd..

• 1990 – Aldicarb• 1990 – Quintozene (PCNB)• 1994 – Pentachlorophenol• 1995 – Methamidophos• 1995 – Monocrotophos (restricted to

coconut)• 1996 – Chlordane• 1998 - Endosulfan

FIRST AIDSkin contact: Remove contaminated clothes

carefully. Wash the skin with running water

for at least 15 minutes. Do not use any local application

without seeking medical advice.

FIRST AID Contd… Wash eyes with running water

for at least 15 minutes. Do not use any eye drops

without seeking medical advice. If there is visual impairment

seek medical advice from an Ophthalmologist.

FIRST AID Contd…• Inhalation:

Remove the patient away from the source and encourage deep breathing of fresh air.

• Ingestion:Do not induce emesis because some pesticides have corrosive effects and some may contain hydrocarbons as solvents.If patient is semiconscious or unconscious keep the patient in Neck extended position.

Management of Organophosphate and Carbamate poiosning

Contd…• Atropine:

The following features of cholinergic syndrome is an indication for atropine therapy.

• Poor air entry in to the lungs due to bronchorrhoea and bronchospasm.

• Excessive sweating• Bradycardia• Hypotension• Miosis

Management of Organophosphate and Carbamate poiosning

Contd…• Initial dose: 1.8 – 3 mg, 3-5 of 0.6

mg vials rapidly IV into a fast flowing IV drip depending on the condition.

• After 5 min. check the five parameters and if there is no improvement double the dose.

Management of Organophosphate and Carbamate poiosning

Contd…• Once atropinised clinical features:

– Clear lungs– Adequate heart rate ( > than 80 beats/m.)– Blood pressure (> 80 mmHg systolic)– Dry skin – Pupils no longer pinpoint– Set up an infusion with 10-20% of total

amount of atropine.

Management of Organophosphate and Carbamate poiosning

Contd…• Target end points for atropine therapy.• Clear chest on ausculatation with no

wheeze.• Heart rate between 80-100 beats/min.• Pupils no longer pinpoint.• Systolic blood pressure > 80 mmHg.• Dry axillae.

Management of Organophosphate and Carbamate poiosning

Contd…• Excess atropine causes confusion,

urinary retention, hyperthermia, bowel ileus and tachycardia.

• In this condition atropine should be ceased and the patient reviewed after 30 min. to see whether the features of toxicity have settled.

• When atropine toxicity settles 70-80% of the previous rate.

Management of Organophosphate and Carbamate poiosning

• Pralidoxime:Give 30 mg/kg loading dose of pralidoxime over 10-20 min. followed by a continuous infusion of 8-10 mg/kg per hour until clinical recovery (for example 12-24 hours after atropine is no longer required or the patient is extubated) or 7 days which is later. Less severely poisoned patients can be given intermittent doses (1 gram 6 hourly by slow IV bolus over 10 – 20 mins).

• Oximes are not required for carbamate poisoning.

Management of Organochlorine

poisoning• For convulsions give diazepam 5-10 mg

IV slowly (Paediatric dose 0.2 mg/kg). Repeat if necessary. Up to 40 mg/day can be given orally as maintenance dose.

• Continue diazepam for 3-4 days after convulsions have been controlled. 10 ml of 10% calcium gluconate IV can also be used to control convulsions.

Management of Paraquat poisoning

• An absorbent (Fuller’s earth or Activated charcoal) should be given orally or via a nasogastric tube as early as possible.

• The dose of Fuller’s earth is 1 litre of 15% aqueous suspension (Paediatric dose 15 ml/kg body weight).

• If Fuller’s earth is not available give activated charcoal 50-100g dissolved in 200 ml of water (Paediatric dose 15 ml/kg body weight).

Management of Propanil poisoning

• If symptoms of methaemoglobinaemia are present (tachycardia, tachopnoea or confusion) or if the levels are over 30%, give 1% methylene blue 0.1 ml/kg IV over 5 minutes. The same dose may be repeated within 1 hour if there is no improvement.

• If IV preparation is not available give methylene bluee 300 mg daily orally. If methylene blue is not available give ascorbic acid 1 g IV twice daily.

Management of Rodenticide poisoning

• If there has been no bleeding, but the PT is prolonged, give vitamin K1 10-50 mg orally two to four times a day (paediatric dose 0.4 mg/kg/dose).

• For prolonged PT with less severe bleeding, give vitamin K1 10 to 15 mg SC or IM (for a child 1 to 5 mg).

• In severe haemorrhage with prolonged prothrombin time (PT) give vitamin K1 (phytomenadione) 20 mg by slow IV injection (0.6 mg/kg for children under 12 years).

• In severe bleeding, it may be necessary to give fresh frozen plasma or fresh blood.

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