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Metal phosphides as arodenticides

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toxicology

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Metal phosphides as arodenticides

  1. 1. ‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬
  2. 2. Prepared by Dr / Hend Gamal
  3. 3. Introduction  Rodenticides are a heterogeneous group of compounds that exhibit markedly different toxicities to humans and rodents. They are among the most toxic substances regularly found in homes.
  4. 4. Types of Rodenticides  Carbamates  Metal phosphides : • Zinc phosphide • Aluminum phosphide  Anticoagulants  Strychnine  Others as thallium,yellow phosphorus and arsenic.
  5. 5. Case presentation  25 years old male patient came to Ain shams poison control Centre with history of black fine powdered rodenticide ingestion from 2hrs , he was vitally stable and clinically free and emesis was done to him by using sodium bicarbonate and the patient admitted in the hospital.  1hr later the patient complained from vomiting and epigastric pain , investigations were done (ECG , ABG and liver functions) alls are normal except pH was 7.20 and bicarbonate was 11 mmol/l .
  6. 6.  Then the patient transferred to ICU for correction of metabolic acidosis .  6 hrs later the patient became very irritable and the liver functions test show elevated liver enzymes .  4 hrs later the patient suffered from flapping tremors and disturbed conscious level .  What was this rodenticide ?
  7. 7. zinc phosphide Zinc phosphide is an inorganic compound that combines phosphorus with zinc. It is a black powder used in rodenticide baits. with a characteristic fishy odour. 3 Zn + 2 P → Zn3P2
  8. 8. How does zinc phosphide work?  When zinc phosphide is eaten by either an animal or a person, stomach acid causes it to release the toxic gas phosphine.  The phosphine in the stomach then crosses into the body's cells, and stops the cells from producing energy by Inhibition of cytochrome oxidase enzyme leading to inhibition of aerobic metabolism that leads to lactic acidosis and cell death.  Zinc phosphide affects all cells, but targets cells in the heart, lungs, and liver.
  9. 9.  Its main effect is metabolic acidosis, hepatotoxicity and cardio toxicity. Fatal dose  There are documented cases of adults dying from massive doses of the Zinc Phosphide (4 g to 5 g) although others have survived acute exposure of as high as 25 g of zinc phosphide if vomiting occurred early and pre exposure to moisture.
  10. 10. Clinical picture  Irritability and restlessness are the earliest symptoms to appear  Vomiting ,diarrhea and dehydration.  hypotension , chest tightness, coldness, unconsciousness and coma .  Toxic cardiomyopathy with dysrhythmia.  Sever toxic hepatitis .  Death can occur from pulmonary oedema and liver damage.
  11. 11. Management Diagnosis:  History and clinical picture  investigations: ECG , ABG and liver functions. Treatment:  ABC  Elimination: emesis or GL is done using NaHCO3.  symptomatic treatment:
  12. 12.  IV fluids and electrolytes to correct electrolyte imbalance  inotropics and antiarrhythmic for toxic myocarditis .  Liver support
  13. 13.  In 2008"After fully assessing human health and ecological effects, as well as benefits The US Environmental Protection Agency made restriction to the use of zinc phosphide.  It is classified as a federally restricted use pesticide because of its hazard to non target species and its acute toxicity to humans.  But in Egypt it is still used with easy availability in homes !!!!!!
  14. 14. ‫هامة‬ ‫أحداث‬ ‫السوس؟؟‬ ‫أقراص‬ ‫هى‬ ‫ما‬
  15. 15. ”‫األخبار‬ ‫جريدة‬2012: ‫أصيب‬‫لمركز‬ ‫التابعة‬ ‫سرحان‬ ‫جرف‬ ‫بقرية‬ ‫طالب‬ ‫أقراص‬ ‫تناوله‬ ‫إثر‬ ،‫تسمم‬ ‫بحالة‬ ‫بأسيوط‬ ‫ديروط‬"‫سوس‬"‫بطري‬ ‫الغالل‬‫ق‬ ‫الخطأ‬. ‫بوصول‬ ‫يفيد‬ ‫ا‬ً‫إخطار‬ ‫تلقت‬ ‫قد‬ ،‫أسيوط‬ ‫أمن‬ ‫مديرية‬ ‫كانت‬‫طالب‬(19‫سنة‬) ,‫ب‬ ‫مصابا‬ ،‫المركزي‬ ‫ديروط‬ ‫مستشفي‬ ‫إلي‬ ،‫سرحان‬ ‫جرف‬ ‫بقرية‬ ‫ومقيم‬‫هبوط‬ ‫أقراص‬ ‫تناول‬ ‫بسبب‬ ،‫والتنفسية‬ ‫الدموية‬ ‫بالدورة‬"‫سوس‬"‫ال‬ ‫الغالل‬‫وتم‬ ،‫سامة‬ ‫الجامعى‬ ‫أسيوط‬ ‫مستشفى‬ ‫إلى‬ ‫نقله‬. ‫عمه‬ ‫وسؤال‬ ‫باالنتقال‬(53‫سنة‬)‫بتناول‬ ‫قرر‬ ،‫القرية‬ ‫بذات‬ ‫ومقيم‬ ،‫عامل‬ ‫ب‬ ‫ًا‬‫د‬‫أح‬ ‫يتهم‬ ‫ولم‬ ،‫الخطأ‬ ‫بطريق‬ ‫السوس‬ ‫أقراص‬ ‫المذكور‬ ‫شقيقه‬ ‫نجل‬‫التسبب‬ ‫ذلك‬ ‫فى‬.
  16. 16. ‫الوفد‬ ‫جريدة‬2012: ‫تلقت‬‫مدير‬‫ية‬‫وصول‬ ‫يفيد‬ ً‫ا‬‫إخطار‬ ‫أسيوط‬ ‫أمن‬‫العمر‬ ‫من‬ ‫تبلغ‬ ‫فتاه‬‫ـ‬19‫سنة؛‬ ‫مجهولة‬ ‫أقراص‬ ‫تناولها‬ ‫إثر‬ ‫هامدة‬ ‫جثة‬ ‫منفلوط‬ ‫شرطة‬ ‫ببندر‬ ‫ومقيمة‬.  ‫ـ‬ ‫المتوفية‬ ‫والد‬ ‫وسؤال‬ ‫باالنتقال‬51‫أن‬ ‫قرر‬ ‫؛‬ ‫عطارة‬ ‫محل‬ ‫صاحب‬ ‫ـ‬ ‫سنة‬ ‫سوس‬ ‫قرص‬ ‫تناولت‬ ‫كريمته‬‫الغالل‬ ‫لحفظ‬ ‫يستخدم‬‫الخط‬ ‫طريق‬ ‫عن‬‫مما‬ ‫أ‬ ‫في‬ ‫بالتسبب‬ ً‫ا‬‫جنائي‬ ‫أحد‬ ‫في‬ ‫يشتبه‬ ‫أو‬ ‫يتهم‬ ‫ولم‬ ‫وفاتها‬ ‫إلى‬ ‫أدى‬‫ذلك‬. ‫أن‬ ‫قرر‬ ‫؛‬ ‫الصحة‬ ‫مفتش‬ ‫بمعرفة‬ ‫الجثة‬ ‫على‬ ‫الطبي‬ ‫الكشف‬ ‫بتوقيع‬‫سبب‬ ‫الدموية‬ ‫بالدورة‬ ‫حاد‬ ‫هبوط‬ ‫الوفاة‬‫و‬‫التنفسية‬.
  17. 17. Aluminium phosphide ‫الغلة‬ ‫اص‬‫ر‬‫أق‬ –‫السوس‬ ‫سم‬  Powdered Aluminium (Al) and Red Phosphorus (P) reacts with each other and produces Alp. Present in the form of tablets each is about 3gm, grey in colour and has a smell that resembles that of garlic or rotting fish.  Aluminium Phosphide Applications It can be used as:  Fumigant  Rodenticide  Insecticide
  18. 18. Epidemiology  Aluminium phosphide poisoning is wide spread in various parts of the world especially in developing countries where it is extensively used as a highly toxic, low cost rodenticide and grain preservative .  Because of its easy availability in the household it has become an important means of self poisoning.  Trade names: Quickphos, cellphos and phostoxin.
  19. 19. Mechanism of action  Upon exposure to moisture, water and air it liberates phosphine gas, which is absorbed rapidly by inhalation and gastro intestinally.  The phosphine in the stomach then crosses into the body's cells, and stops the cells from producing energy by Inhibition of cytochrome oxidase enzyme, leads to lactic acidosis and cell death.  a fatal dose is between 150mg and 500mg.
  20. 20. Mortality rates  The mortality rates from ALP vary from 45–80%. The actual numbers of cases may be much larger, as less than 5% of those with ALP eventually reach a tertiary care centre  It has been reported to be the most common cause of suicidal death in India.  Other reported cases in Egypt , Nepal, new zeland, Saudi Arabia, Morocco and Tehran.
  21. 21. Clinical Manifestations  Aluminium phosphide poisoning is systemic and it affects various organ systems like the cardiovascular, gastrointestinal, renal ,respiratory and hepatobiliary system.  Gastrointestinal Manifestations: include epigastric discomfort, nausea, and vomiting and burning sensation in stomach.
  22. 22.  The cardiovascular involvement : take the form of myocarditis, peripheral circulatory failure, arrhythmias or cardiac failure. Electro-cardio graphic abnormalities include ST-T wave changes, supra ventricular tachycardia with conduction defect, atrial fibrillation, bundle branch block and ventricular tachycardia.  Nervous system involvement: occurs in the form of headache, paraesthesia, dizziness and tremors.
  23. 23.  majority of patients come in shock with impalpable pulse, cold extremities, restlessness, palpitation and tachypnea.  Occasionally cases may come with picture of adult respiratory distress syndrome (ARDS), pulmonary oedema, acute renal failure and peripheral circulatory failure often leading to death which is serious complications
  24. 24. Diagnosis   The diagnosis is based on reliable history and or the production of remaining tablets empty container by the attendants of the patient for identification. Patient’s breath has garlic like smell  Further confirmation can be made by subjecting the gastric lavage fluid to silver nitrate test,this test is based on the property of PH3 to reduce silver nitrate to metallic silver which appears black to the naked eye.
  25. 25. Management  There is no known antidote to aluminium phosphide and management of the patient is mainly supportive in order to sustain life till phosphine is excreted from the body by lungs and kidneys.  There is controversy about the use of magnesium sulphate but then magnesium sulfate is used because of its anti-arrhythmic action. Intravenous magnesium sulphate (a loading dose of 4 gm. over 4 hours followed by 1 gm. I/V 6 hourly) and Calcium gluconate is beneficial because of its cardio protective action.
  26. 26. Successful treatment of acute aluminium phosphide poisoning: In the Poison control Centre, Loghman-Hakim Hospital, University of Medical Sciences Tehran, Iran. A medical staff members said that they used the following protocol in a 28-years old man who had ingested a lethal amount (12 g) of aluminum phosphide with suicidal intent and was admitted to hospital approximately 6 hours post ingestion. The patient had signs and symptoms of severe toxicity, and his clinical course included metabolic acidosis and liver dysfunction.
  27. 27. Treatment consisted of gastric lavage with potassium permanganate solution, intravenous administration of sodium bicarbonate, magnesium sulphate and calcium gluconate, and oral administration of coconut oil as rapid prevention of absorption by coconut oil might be helpful. Conservative and supportive therapy in the Intensive Care Unit was also provided. The patient survived following rapid treatment and supportive care..
  28. 28. It is concluded that coconut oil has a positive clinical significance and can be added to the treatment protocol of acute aluminum phosphide poisoning .

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