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PRACTICAL WORK №6

RISK ASSESSMENT OF CHEMICAL HAZARDS

1 OUTCOMES
Become familiar with risk assessment of chemical hazards, terms, and
carrying out the necessary calculations of long-term and emergency forecasts.

2 DURATION OF CLASS
The class duration is four academic hours.

3 BASIC THEORY
Thousands of people are exposed to hazardous chemical agents at work. If
the exposure is not prevented or properly controlled, it can cause serious illness,
sometimes even death. The effects of hazardous chemicals may be immediate or
long-term and range from mild eye irritation to chronic lung disease.
Hazardous chemical agents include:

• Substances brought into the workplace and handled, stored and used for
processing (e.g. raw materials, solvents, cleaning agents, glues, resins, paints);
• Substances generated by a process or work activity (e.g.fumes from
welding/soldering, dust from machining of wood, solvent vapours from painting,
dust from quarrying);
• Substances or mixtures produced by the work process including by-
products, residues or waste.
Chemical agents can be considered hazardous not only because of what they
contain, i.e. as a constituent or chemical ingredient, but because of the form or way
in which they are used at the workplace e.g. hot water used as steam can cause
very severe burns and control measures need to be specified to prevent harm.
Some examples of the effects of hazardous chemicals include:
• Skin burns or irritation caused by contact with a corrosive liquid;
• Being overcome or losing consciousness following inhalation of toxic
fumes;
• Suffering acute symptoms such as headache or nausea within hours of
inhalation;
• Poisoning by absorption through the skin of a toxic substance;
• Asthma;
• Dermatitis;
• Cancer occurring years after exposure to a carcinogenic substance;
• Genetic damage to offspring occurring years after exposure to a mutagenic
substance.
MAC (Maximum Allowable Concentration) values are set to ensure health
and safety at the workplace.
The MAC value of a substance is the highest concentration in which a
substance may be present in the laboratory atmosphere in gaseous, vapour or

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