by mtoom


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Is environmental and occupational disease common or uncommon?
Common
Can you usually distinguish the clinical and pathologic expression of occupational versus non-occupational disease? Are occupational and non-occupational mutually exclusive?
No, you generally cannot distinguish occupational and non-occupational disease based on pathologic characteristics.

And, they are often not mutually exclusive either. Disease is multifactorial, so it can be both occupational and due to smoking, for example.

For example, asbestos exposure and smoking together are substantially worse than either condition alone.
Describe when you would see the effects of occupational exposures, relative to when they occur.
Generally, they occur after a biologically predictable interval (ie. "latency period").
In occupational disease, what is the strongest predictor of the likelihood and type of effect on health outcome?
Dose of exposure
Do people react in a similar fashion to noxious exposures?
No, they differ in responses
Describe 7 types of exposures and give examples
  • Natural (e.g. sand)
  • Combustion (e.g. vehicle exhaust; cigarette smoke)
  • Synthetic (e.g. consumer products, such as phthalates)
  • Agriculture (e.g. grain dust)
  • Chemical reactions (anticipated and unanticipated)
  • Unknown (suspected in sarcoidosis)
  • Indoor (cleaning products) versus outdoor (ozone)
Describe 6 types of exposure patterns (use examples)
  • Magnitude (large vs small; insidious vs accidental)
  • Context (occupational vs environmental)
  • Persistence (acute vs chronic)
  • Duration (steady vs intermittent; seasonal, ozone in summer; diurnal, traffic-related)
  • Geography (large vs small, valleys vs flats)
  • Conditions (exertion, personal protection)
  • How much time do Canadians spend indoors?
  • Contaminants of indoor air originates where?
  • 80%
  • Outdoors
Are effects different in acute vs chronic exposures?
Yes
  • Acute exposureacute effects (but also sometimes chronic)
  • Chronic exposurechronic effects (but also sometimes acute)
What are the 3 major factors determining the lung's response to pollutants?
  • Deposition
  • Clearance/detoxification
  • Biologic activity of substance
What affects the deposition of a Gas versus a Particle? Relate how these things determine how far into the airways these pollutants will go.
  • Gas: Governed by Solubility (↑Henry's constant → Further into airway, ie. small airways)
  • Particle: Governed by Aerodynamic diameter rather than weight (↓Diameter → Further into airways)
What clearance of contaminants from the lungs depend on what 2 mechanisms?
  • Site of deposition
  • Health of lung defenses
    -- nasal filtering
    -- cough/sneeze
    -- mucous/mucociliary
    -- alveolar macrophages, lymphocytes
    -- bactericidal enzymes, antibodies
    --lymphatic system
What 8 other factors have an impact on toxicity of pollutants?
  • Nature of activity (eg. exercising away from highway)
  • Ventilation (key in acute context)
  • Location (work, home, outdoors)
  • Use of antioxidants and medications (to prevent further damage after exposure)
  • User of air cleaners
  • Use of masks
  • Reduction of cardiovascular risk factors
  • Genetics
How are inhaled substances (i.e. pollutants) biologically active? Describe 2 classes.
Non-specific chemical reactivity
  • Reactive oxygen species
  • Strong acids/bases
Specific toxic effects
  • Displace oxygen, simply by gradient (CO2, methane, N2)
  • Disrupt blood's O2-carrying capacity (HCN, CO, HS)
  • DNA strand breaks (polycyclic aromatics)
  • Invoke allergic responses (isocyanates)
Name 4 general mechanisms of how pollutants damage health
  • Mutation
  • Inflammation (→ Necrosis → Fibrosis)
  • Allergic reaction (sensitization)
  • Oxidative stress
Provide 8 disease states in the respiratory tract that are caused by or exacerbated by pollutants.
Includes most of the obstructive and restrictive diseases we discussed:
  • Rhinitis
  • Laryngitis
  • Bronchitis
  • Bronchiolitis
  • Asthma
  • COPD
  • Cancer
  • Interstitial disease

He mentions sarcoidosis as well, so you can throw that in.
What are 4 areas of industrial hygiene that help to prevent/minimize occupational harm
  • Engineering (Replace/redesign unsafe equipment/processes)
  • Administrative controls (Retraining, surveillance)
  • Work practice controls (Locks, ventilation)
  • Personal protective equipment (masks, barriers)
What condition does asbestos exposure cause? How long is the latency?
Mesothelioma (cancer of mesothelium in lung)

30 years latency
What condition does silica exposure cause? How long is the latency? What type of disease is it?
Silicosis

Latency is 10 years, it is a restrictive disease, a type of pneumoconiosis
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