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11.10.2 Toxic Hazards


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Toxic Materials

All pilots will be exposed to a variety of chemical agents that are toxic. A general knowledge of the effects of these materials is required.


Toxicology is defined as: The study of the nature and mechanism of toxic effects of substances on living organisms and other biological systems.

Toxicity depends on:

  • The amount of exposure.
  • The dose.
  • The duration of exposure.

Toxic materials can affect any organ of the body. The major organs that can be affected are the lungs, liver, kidney, skin, eyes, nervous system, reproductive system, heart and immune systems.

Aviation Gasoline (AVGAS)

Exposure may occur during handling, storage, or engine maintenance. It may be inhaled or absorbed. AVGAS fumes are an upper respiratory irritant. Rapid vaporisation of AVGAS can cause chemical skin burns if next to the body.


JP4 and JP5 are jet engine fuels; JP4 is 65% kerosene and 35% gasoline, while JP5 is kerosene. They may cause headache, nausea, confusion, drowsiness. Prolonged skin exposure can lead to second degree burns.

Ethylene Glycol

Used in antifreeze, hydraulic fluids, condensers and heat exchangers. Ingestion can be fatal.

Methyl Alcohol

Methyl alcohol causes disturbances of vision, headache, vertigo, nausea and vomiting. Methyl alcohol is found in de-icing fluid. If drunk in large amounts then blindness can occur.

Chlorobromo Methane (CBM)

A constituent chemical used fire extinguishers. Absorb by inhalation and skin absorption. CBM is considered safe for flight crew.


Halon is a generic term meaning halogenated hydrocarbon. The gas is a CNS depressant. Used as a flooding agent to extinguish fires in simulator buildings.

Hydraulic Fluid

Hydraulic fluid is petroleum based and inflammable. When burned, phosgene is formed. This toxic gas affects the respiratory system. Inhalation is possible when a hydraulic line breaks under pressure.


Plastic burns to CO and other toxic gases. Absorption is through inhalation. Burning plastic creates a black, choking, toxic smoke that quickly incapacitates.


Mercury is a metal liquid at room temperature. The vapour can be absorbed by inhalation.


In-flight pilot incapacitation is known to have caused accidents and occurs frequently enough for flight crew to train for the possible consequences.

Despite strict medical standards incapacitation still continues to occur. Temporary incapacitation may be less dramatic than a total collapse but is just as much of a problem. Most temporary collapses are caused by gastrointestinal upsets.

Incapacitation can be divided, "obvious" and "subtle" incapacitation.

Obvious Incapacitation

Obvious incapacitation is immediately apparent to other flight crew members. Occurring suddenly, attacks are usually prolonged and normally result in that flight crew member being useless for the rest of the sortie. Sudden incapacitation may not be preceded by any warning.

Subtle Incapacitation

Subtle or insidious incapacitation is harder to identify because it is not obvious. Subtle in its onset it is hard to predict or notice. This form of incapacitation can be dangerous because of the time it takes for a crewmember to notice the effects.