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  1. Occurrence, course of events, and causes of a chemical accident and the environmental and ecological consequences English Mira Arnold, Tashi Gurung, Joanna Lihs

  2. Phosgene Definition of phosgene Physical properties History of phosgene Effect on humans I Effect on humans II Protection measures Earlier use of phosgene Today‘s use of phosgene A phosgene accident in Uerdingen Directives

  3. Definition of Phosgene Phosgene may be created when ultraviolet light interacts with chlorinated hydrocarbons: CO + Cl2COCl2 phosgene

  4. Physical Properties • Colourless gas (at 20°C), smells of rotting hay and rotting apples. • Soluble in organic solvents (acetone, benzene, toluene), oils, fats, by-products, chloropicrine and arsine dichloride. • Hydrolysis takes place in cold water by quickly adding an alkali. Hydrogen chloride and carbon dioxide form. • Melting point: -127.9°C Boiling point: 7.48°C • Solubility in water: low

  5. Toxicity Overview of the effect of phosgene on humans when used as a chemical weapon: LD50= fatal dose for 50% of victims (in mg pro kg body weight) LCt50 = fatal concentration for 50% of the victims (in mg per liter air for the time span of one minute) LD50LCt50ICt50 12 3,2 1,6 ICt50= This is the concentration which renders 50% of victims incapable of action (in mg per liter air for the time span of one minute)

  6. Effect on Humans I • Reaction with water, e.g. in the lungs where it forms hydrochloric acid and carbon dioxide • Blocks metabolic enzymes • The first symptoms of poisoning: tears, coughing and breathing problems • Death follows some hours later due to a lung oedema or cardiac arrest

  7. History of the Discovery of Phosgene Phosgene was discovered in 1812 by the English chemist, Sir Humphrey Davy (1778-1829). Davy discovered it when he exposed chloro-carbon monoxide to intense light. This explains why the chemical is called phosgene (= luminous green).

  8. Effect on Humans II • Mild symptoms: • Running eyes (relatively fast) • Coughing • Irritation of the upper respiratory tract • Serious symptoms: • Breathlessness, sometimes resulting suffocation • Lung oedemas • Inner bleeding in the lungs • Cardiac arrest

  9. Protection Measures • Specialised staff or military personnel: • ABC-suits and ABC-gas masks (only to be worn for a limited time span) • Filters must be renewed frequently due to the high concentration of the poison • Population: • practically no protection possible against surprise attacks • Effective protection measures can only be carried out by stopping phosgene attacks.

  10. Early Use of Phosgene In the First World War phosgene was one of the first chemical weapons to be used and today it is one of the most poisonous industrial chemicals. When phosgene has contact with water it hydrolyses to hydrochloric acid and becomes poisonous for the lungs. CoCl2 + H2O  CO2 + 2HCl Next page

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  12. In addition, phosgene was used during the First World War in grenades, mines, incendiary devices and cylinders. back

  13. Today‘s Use of Phosgene • Phosgene is very reactive. • It is used for producing intermediate products for colourings, plastics and organic syntheses such as pharmaceutical products or pesticides • Phosgene can also emitted while welding if chlorated carbons are present

  14. Phosgene as a by-product in the manufacture of polyurethane Polyurethane is used for insulation, swimming costumes and for tights and stockings.

  15. Manufacture of polycarbonates using phosgene Polycarbonates (PC) are synthetic polymers and belong to the group of polyesters. PC is used for airplane windows, CDs, DVDs, electrical components and other kinds of apparatus.

  16. A Phosgene Accident in Uerdingen In December 2001 an accident occurred at the Bayer company in the department producing phosgene. An employee from an outside firm suffered poisoning during this incident. No information on the accident has been provided to the public due to secrecy requirement stipulated by occupational safety laws and the Trade Secrets Act. Why does Bayer produce phosgene ?

  17. Use of Polycarbonates in different industrial sectors:

  18. Directives Phosgene: CCl2O T+ Safety procedures during an accident Leave the room immediately! During uncontrolled emission wear a protective suit and use a gas mask that is not dependent on circulating air. If water is used hydrochloric acid will form.

  19. First Aid After skin contact: Wash immediately with water (better: with sodium carbonate). After eye contact: Rinse immediately for at least 15 minutes and keep the contaminated eye open during this time. After inhaling: Ensure fresh air, do not give the victim anything to drink. Auxiloson spray – 10 doses every five minutes. Call a doctor immediately. After contact with clothes: Remove contaminated clothing immediately. Soak clothing in ammoniac solution to clean. First Aid helpers: Refer to published safety procedures.