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Chapter # 6
Chemical Hazards
PG
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◦ Has specific volume
◦ Compressed only a negligible even at moderately high pressures
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◦ Has no fixed volume but is compressed or expanded as its container changes in size

Vapour:
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Gaseous state of substance that is liquid or solid at room temperature
Evaporation produces vapor and is significantly effected by room temperature and pressure
Many chemicals evaporate at room temperature
Solvents in paints, glue and cleaners
Volatile: Liquids that evaporate easily
Benzene, methyl ethyl ketone, perchloroethylene are examples of hazardous liquids
Dry ice: solid CO2
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5C carbon dioxide becomes solid
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◦ Paint spraying is another workplace activity that generates mists

Dust
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Consists of very small particles that can become airborne
Created when solid materials are crushed, ground or sanded
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• Some of the solid evaporates and vapor enters the air
• The vapor cools and the tiny solid particles remain in the air as fumes
• Fume particles are usually less than 1 micrometer in diameter
• Welding produces fumes
•Smoke
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Made up of carbon particles called soot which I result of incomplete combustion
Produced when fossil fuels such as wood, coal, oil or other substances are burned (contain carbon)
Incomplete combustion some material is not consumed by burning process
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◦ Soluble substances enter dissolve in mucous lining causing inflammations in lungs
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◦ Some substances will remain in lungs following inhalation and produce disease there e
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◦ Some substances can pass into the bloodstream and cause diseases in other parts of body e
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◦ Routes to ingestion are:
◦ Poor personal hygiene
◦ Eating and drinking in the work areas
◦ Smoking in contaminated work place area
◦ Highly caustic materials like sodium hydroxide has been shown to be capable of causing
serious damage to lining of GI tract when accidentally ingested
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Absorption:
◦ Entry through skin or eyes but mostly through hands
◦ Hexane, carbon tetrachloride and insecticides are examples of such substances
which are absorbed by skin, carried through the bloodstream and cause harm in different
part of body

◦ Healthy skin is a good barrier to absorption
◦ Wet skin, cuts, scratches, lesions or abrasions can all increase the transfer of contaminants
through skin
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◦ Oil rags placed in pockets can transfer oil to clothing which then remains in contacts with skin for long
time and increases absorption
◦ Gloves can become contaminated on the inside where the contaminant stays in a warm, most area n
close contact with skin and is in perfect environment to increase absorption
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o Delay period can range from a few weeks upto 40 to 50 years or more
o Lung cancer from smoking
o Depending on how heavy the exposure to silica it is possible to develop silicosis in a few months to a year but
likely in 40 to 50 years
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◦ A block of metallic lead on the ground is not hazardous but a metal if heated becomes a fume then it is hazardous
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◦ Effects are usually seen immediately

Local vs systemic poisons
◦ Local poison are those that produce an effect at the application site
◦ Concentrate nitric acid on skin burns it and turns it orange
◦ Carbon tetrachloride is absorbed through the skin and produces effects elsewhere like on the liver

Allergens:
◦ These substance react with the body’s immune system to produce a delayed type of irritation known as an
allergic reaction
◦ Result may be a skin rash or a wheezing/ panting condition
◦ Once sensitized people need only be exposed to very small quantities to be affected
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◦ Arsenic, beryllium, ether, chromium(VI) compounds are few examples of human carcinogens
◦ Animal carcinogens : tests on animals may produce a cancer which is not observed when humans are exposed
to same substance

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