Dr. Saeid Akbari IRANIAN CIVIL AVIATION ORGANIZATION Aviation Toxicology

The pathological investigation of fatal aircraft accident victims relies on analytical toxicology to establish the nature and concentration of substances such as alcohol, drugs and products of combustion that may have impaired the aircrew and so contributed to the accident, or impaired the passengers in their attempts to escape the crashed aircraft.

LD 50 LD 50 : The dose expected to be lethal in 50% of the animals. The LD 50 is expressed in mg/kg of body weight ( milligrams/kilogram )

LC 50 LC 50 : The concentration expected to be lethal in 50% of the animals. The LC 50 is expressed in part per million ( ppm )

The LD 50 and LC 20 allow a ranking of chemicals from extremely toxic ( LD 50 less than 1mg/kg or LC 50 less than 50 ppm ) to relatively harmless ( LD 50 more than 15 g/kg or LC 50 more than ppm )

Particles greater than 10 micrometer are filtered out by the nose, particles between 10 micrometer and 5 micrometer are trapped in the bronchi and are removed by the cilia. Particles smaller than 5 micrometer reach the alveoli and may cause disease.

Sources of toxic hazards in flight 1. Products of combustion: engine exhaust gases; products of overheating or fire. 2. Aviation fuels, lubricants and hydraulic fluids. 3. Anti-icing, anti-detonant and coolant fluids. 4. Fire extinguishing agents. 5. Refrigrants. 6. Ozone. 7. Insecticides, herbicides and agricultural chemicals.

Chemical hazards to ground crew are provided mainly by aircraft fuels, lubricating oils, hydraulic oils, anti-icing fluids and coolants. These substances may be hazardous because they are potentially explosive, flammable, toxic, corrosive or irritant, or they may present a hazard to the environment when spilled.

Fuels, composed essentially of hydrocarbons, present the greatest risk since they are present in very large volumes and are extremely flammable. There is therefore a risk of explosion and fire. Spillage of fuel onto the skin or clothing may cause chemical burns and inhalation of high concentration in poorly ventilated area may cause headache and ultimately narcosis. FUELS

These fluids are not volatile and are less flammable than fuel. They may cause sensitization if they come into contact with the skin or eyes. Lubricating oil and hydraulic fluids :

In aqueous solutions these substances do not present a particular hazard, however skin contact is best avoided. Accidental ingestion of moderate quantities of ethanediol can be fatal and medical assistance must be sought in this case. Anti-icing fluids: