Cyanides

1. Cyanides

2. Cyanides • Discoverer Karl Wilhelm Sheele died from its vapors • Commercial and home use • Found in some fruit seeds • Accidental poisonings from apricot kernels

3. Cyanides-Overview • HCN and CK • Highly volatile • Easily dispersed as aerosols • Readily soluble and stable in water • Major route of toxicity is inhalation • Aroma of bitter almonds or marzipan • CK has cumulative effect on victims

4. Cyanides-Toxicity • Inhibits oxidizing enzymes containing ferric iron, mainly cytochrome oxidase • Interferes with aerobic respiration • Lactic acid accumulates and cells die from a histotoxic anoxia • Alters calcium metabolism

5. Cyanides-Toxicity • Hydrogen Cyanide (HCN) • 60 mg•min/m3 - No serious symptoms • 200 mg•min/m3 - Fatal after 10 minutes • Above 2,500 mg•min/m3 - death within a minute

6. Cyanides-Toxicity • Cyanogen Chloride (CK) • Pulmonary irritant like phosgene • 2.5 mg•min/m3 - irritation after 10 minutes • 5 mg•min/m3 - intolerable at 10 minutes • 400 mg•min/m3 - fatal after 10 minutes

7. Protective Equipment • Chemical protective clothing required • Respirator filters containing silver oxide offer effective protection • Change filter immediately after exposure

8. Detection • Several analytical detecting methods are available • Main method of laboratory detection is gas chromatography/mass-spectrometry

9. Decontamination • First priority: remove victims from area • Skin: wash well with soap and water • Eyes: flush well with water or saline • Decontamination of clothing or equipment is unnecessary

10. Signs and Symptoms • Diagnosis • History • Abrupt onset of symptoms • Bitter almond odor on the breath • Mild HCN cases • Headache • Vertigo • Nausea

11. Signs and Symptoms • Low HCN concentrations • Apprehension, dyspnea, headache, vertigo and a metallic taste are seen initially • Convulsions and coma may follow and can last for hours or days

12. Signs and Symptoms • Low HCN concentrations • Prolonged coma, residual CNS damage may be seen • Irrationality, altered reflexes, unsteady gait • Nerve deafness also possible

13. Signs and Symptoms • High concentrations • Throat constriction, giddiness, confusion, decreased vision, vice-like gripping of the temples, and pain in the back of neck and chest • If unconsciousness follows, further exposure can be fatal within 2-3 minutes

14. Signs and Symptoms • Lower but still lethal concentrations • Immediate, progressive sense of warmth, visible flushing • Prostration ensues • Nausea, vomiting, headache, dyspnea and chest tightness • Unconsciousness & asphyxia will follow

15. Signs and Symptoms • Very high concentrations • Main initial symptom: hyperventilation • Loss of consciousness, convulsions, and loss of corneal reflex • Death by cardiac and/or respiratory arrest

16. Signs and Symptoms • Effects are slower to develop to lethal amounts via ingestion or skin exposure • Victim can survive 15-30 minutes • Antidote could be given

17. Signs and Symptoms • CK exposure produces symptoms of cyanide poisoning and lung irritants • Eye exposure • Lacrimation and blepharospasm • Respiratory exposure • Irritation of the nose and throat, cough, dyspnea, and chest tightness

18. Signs and Symptoms • Exposures>50 mg•min/m3 produce pulmonary edema, followed by collapse, coma and death • Liquid CK can cause 2º and 3º skin burns

19. Laboratory/Diagnostics • Useful lab findings include: • High anion gap metabolic acidosis • Elevated lactate, methemoglobin, and urinary thiocyanate levels

20. Laboratory/Diagnostics • EKG • Atrial fibrillation • Ectopic ventricular beats • Abnormal QRS waves with the T wave originating high on the R wave

21. Treatment • Victims asymptomatic after several minutes require no oxygen or antidotes • Administer supportive care, oxygen and antidotes • Acute effects (convulsions, dyspnea) • Acute exposure (unconscious but breathing)

22. Treatment • Treat irritation effects of CK • Wash eyes with a weak boric acid solution • Apply soothing lotions/compresses • Assess and treat burns as you would thermal burns • Control hypoxia with O2 supplementation • Consider early use of IPPB, PEEP or intubation

23. Treatment • For ingestions • Initiate gastric lavage with water • 1:5000 solution of potassium permanganate if available • Antidotes dissociate the cyanide ion from cytochrome oxidase

24. Treatment • Goal: create methemoglobin, which binds to cyanide to form cyanmethemoglobin • Sodium nitrite • Amyl nitrite • 4-dimethylaminophenol-hydrochloride (DMAP)

25. Treatment • Other antidotes • Cobalt in the forms of dicobalt edetate or hydroxocobalamin also combines with cyanide ions • Hydroxocobalamin • Dicobalt edetate

26. Treatment • Therapies are life saving: not curative • Follow these antidotes with sodium thiosulfate to aid the clearance of cyanide as non-toxic thiocyanate

27. Long-Term Medical Sequelae • Low doses: no long-term problems • At near lethal doses: lower intellect, confusion, loss of concentration and Parkinsonism

28. Long-Term Medical Sequelae • Chronic poisoning: ataxic neuropathy • No specific data on developmental and reproductive effects, mutagenicity or carcinogenicity

29. Environmental Sequelae • HCN is highly volatile, removed from the environment in less than an hour • CK is less persistent

30. Summary • Hydrogen cyanide (HCN) and cyanogen chloride (CK) • Cyanide gases • Military and terrorist potential • Inhalation main route of exposure • Decontamination is possible with soap and water but must be done immediately

31. Summary • Cyanide inhibits aerobic respiration at the cellular level • Symptoms are immediate • Supportive care and antidotes are required