1. Trinidad and Tobago National Safety Week
April 28 – May 4, 2013
Recognition and Prevention of
Occupational Diseases
Industrial Hygiene Perspective
Eva Karpinski, M.Sc., P.Eng.
Industrial Hygiene Engineer
Occupational Health and Safety Division
Workplace Directorate

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Definition of Occupational Disease
 Occupational disease – a disease associated with
exposure to a chemical, physical, biological, ergonomic, or
psychosocial hazard in a workplace.
Canadian Standard Association (CSA):
CSA Z795-03 Coding of Work Injury or Disease Information (not
referenced in the COHSR)

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Workplace hazards which may cause occupational
disease
 Chemical hazards – dusts, fumes, smoke, aerosols, mists, gases and
vapours
 Physical hazards – noise, vibration, ionizing and non-ionizing radiation,
thermal stresses
 Biological hazards – bacteria, viruses, fungi, moulds, insects
 Ergonomic hazards – improperly designed tools/work areas, improper
lifting/reaching, repeated motions, mechanical vibrations
 Nanomaterials – materials with any external dimention in the nanoscale or
having internal structure or surface structure in the nanoscale (1 nm to 100
nm)
 Psychosocial hazards – violence, bullying, harassment, other chronic
stressors identified by workers

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Effects of exposure to hazardous substances
 Acute effects – the ill-health effects caused by sudden one-time exposure to
relatively high concentrations of hazardous substances. Most acute effects
are over in a few minutes, hours, days or at most, in a few weeks. Recovery is
complete (e.g. pulmonary edema) or there is a permanent disability or death
(e.g. exposure to IDLH condition).
 Chronic effects – the ill-health effects caused by repeated exposure to
relatively low concentrations of hazardous substances or as long term effect of
a short but severe exposure to a hazardous substance. Recovery is complete
(e.g. tendonitis) or there is a permanent disability or death (e.g. pleural
thickening, mesothelioma).
Latent period – the time from the first exposure to the disease development

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Routes of entry
 Inhalation
 Skin absorption
 Ingestion
 Eyes

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Examples of occupational diseases
 Asthma, e.g., caused or triggered by exposure to isocyanates
 Silicosis, caused by exposure to silica
 Hearing impairment caused by noise
 Tuberculosis, caused by mycobacterium tuberculosis
 Carpal tunnel syndrome, caused by repetitive motions combined
with extreme postures of the wrist and forceful exertions
 Mesothelioma, caused by exposure to asbestos

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Occupational diseases in Canada
Injuries
 Musculoskeletal system disorders continue to rank the highest but are
showing a sharp decline over the 11 year period. (It may be related to
increased knowledge of the importance of ergonomics.)
Note: Musculoskeletal system disorders have made up at least half of
occupational injuries every year in the 11 year period.
 Infectious diseases peculiar to the intestines over the 11 year period
(15% increase from 2001 to 2011, peaking in 2010).
 Other diseases seem to be trending downward.

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Fatalities
• Malignant neoplasms and tumors continue to rank the highest and are
showing an upward trend.
Note1: This disturbing trend is likely due to:
– work practices in the past
– long latency periods
– increased association of adverse health outcomes with work history
– advances in occupational medicine
Note2: This trend is expected to peak within the next few years and then
trend downwards

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Prevention of occupational disease
 Primary prevention – preventing development of disease by taking
necessary measures to eliminate or control worker exposure
 Secondary prevention – early detection of disease, intervention and
treatment to prevent from further development, e.g. medical
surveillance
 Tertiary prevention – medical management of established disease

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Primary prevention of occupational disease
Industrial hygiene elements include:
 anticipation
 recognition
 evaluation
 control
of hazards which may cause illness, impaired health, or significant
discomfort among workers.

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Recognition
In order to recognize a hazard it is necessary to:
 study the process
 identify all the ingredients used and their quantities
 obtain their safety data sheets
 understand the chemistry involved
 identify and quantify all the products and by-products of the
process
 identify sources of contaminant generation

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• establish the toxicity of the hazardous substances and
their limits of exposure
• study their physical properties
• determine the effectiveness of control measures already in place

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Evaluation
If a potential hazard to the health of a worker is identified, the next step
is to evaluate the hazard.
At the evaluation stage, the following factors must be determined:
 the number of employees exposed and the duration of exposure
 the number of samples
 the type of samples and period of activity to be sampled

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• the concentration or level of the hazardous substance to
which a worker is exposed
• whether this concentration or level of the hazardous
substance is in excess of the occupational exposure limit
for that hazardous substance, e.g., TLV

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Types of control measures
Source
 Elimination
 Substitution
 Source or process modification
 Automation
 Isolation/containment/enclosure
 Local exhaust ventilation

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Path
• General ventilation
• Increased distance
Worker
• Good work practices
• Operating procedures
• Job rotation/work scheduling
• Personal protective equipment

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Secondary prevention of occupational diseases
Employers may establish a medical surveillance program for the benefit of
workers that includes:
 medical examination (pre-employment, pre-placement, periodic)
– history, e.g., previous exposure, smoking, signs and symptoms
– physical examination
 clinical tests, e.g., pulmonary function tests, chest x-ray, blood and urine tests
 action levels
 health education, e.g., personal cleanliness, hazards, discussion of examination
results
 record keeping

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Tertiary prevention of occupational diseases
Medical management of established disease

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Questions?
Thank you!