Back to Basics, 2012 POPULATION HEALTH: Environmental

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Back to Basics, 2012 POPULATION HEALTH
Environmental Occupational Health

• B. Pinard, MD (PGY5)
• G. Dunkley, MD
• Epidemiology Community Medicine
• Based on slides prepared by Dr. R. Spasoff and
  Dr. N. Birkett

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MCC Objectives Population health 78-6 Environment

• Rationale
• Environmental issues are important in medical
  practice because exposures may be causally linked
  to a patient's clinical presentation and the
  health of the exposed population. A physician is
  expected to work with regulatory agencies to help
  implement the necessary interventions to prevent
  future illness. Physician involvement is
  important in the promotion of global
  environmental health.
• Terminal Objectives
• Recognize the implications of environmental
  hazards at both the individual and population
  level.
• Respond to the patients concerns through
  appropriate information gathering and treatment.
• Work collaboratively with local, provincial and
  national agencies/governments as appropriate to
  address the concerns at a population level.
• Make appropriate recommendations for patients and
  exposed populations so as to minimize their
  health risks and maximize their overall function.
  
• Enabling objectives
• Identify common environmental hazards and be able
  to classify them into the appropriate category of
  chemical, biological, physical and radiation.
• Identify the common hazards that are found in
  air, water, soil and foods.
• Describe the steps in an environmental risk
  assessment and be able to critically review a
  simple risk assessment for a community.
• Conduct a focussed clinical assessment of exposed
  persons in order to determine the causal linkage
  between exposure and the clinical condition.
• Be aware of local, regional, provincial and
  national regulatory agencies that can assist in
  the investigation of environmental concerns.
• Describe simple interventions that will be
  effective in reducing environmental exposures and
  risk of disease (e.g. sunscreen for sunburns, bug
  spray for prevention of West Nile Virus
  infection).
• Communicate simple environmental risk assessment
  information to both patients and the community.

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78-6 ENVIRONMENT (1)

• Objectives
• - Identify common environmental hazards and be
  able to classify them into the appropriate
  category of chemical, biological, physical and
  radiation.
• - Identify the common hazards that are found in
  air, water, soil and foods.

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78-6 ENVIRONMENT (2)

• Environmental exposure
• Natural and human-made environment
• Reservoirs air, water, soil, food
• Route inhalation, ingestion, absorption
• Exposure setting
• Workplace occupational health (high level
  exposure, acute or chronic)
• Outside workplace environmental health (low
  level exposure, chronic)

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78-6 ENVIRONMENT (3)

• AIR
• Physical contaminants
• Radiation Radon (lung cancer), UV (skin cancer)
• Sound waves (hearing loss)
• Chemical contaminants
• Ozone at ground level (worsens asthma)
• Carbon monoxide (asphyxiation)
• Sulphur dioxide nitrogen oxides (exacerbation of
  breathing problems)
• Organic compounds Benzene (carcinogen
  leukemia)
• Second hand tobacco smoke (lung cancer)
• Heavy metals industrial emissions (specific
  syndromes)

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78-6 ENVIRONMENT (4)

• AIR
• Biological contaminants
• Bacteria Legionella (pneumonia)
• Dust mites (upper and lower-airway sx)
• Pollen (upper and lower-airway sx)
• Moulds (allergies)
• Particulates (pollen, spores, aerosols) (asthma)
• Global warming
• Extreme weather (heat waves), change in
  distribution of vectors of disease, crop
  failures, etc.

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78-6 ENVIRONMENT (5)

• WATER
• Biological agents
• Bacteria E. coli, Salmonella, Pseudomonas
• Protozoa (cysts) Giardia, Cryptosporidium (GI
  symtoms mainly)
• Blue green algae (skin irritation, GI symptoms)
• Higher risk aboriginal Canadians, rural
  population
• Chemical agents
• Volatile organic compounds (VOC), pesticides,
  heavy metals, other waste from industries
  (effects depend on contaminant)
• Chlorination by-products - trihalomethanes (THM)
  (cancer)
• SOIL
• Chemical agents
• Pesticides, petroleum hydrocarbons, solvents,
  motor oil, lead (effects depend on contaminant)
• Higher risk infants/toddlers
• Biological agents
• Bacteria (tetanus)

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78-6 ENVIRONMENT (6)

• FOOD
• Biological Contaminants
• Salmonella- raw eggs, poultry, meat (GI sx)
• Campylobacter - raw poultry and milk (GI sx,
  joint pain)
• E. Coli - hamburger meat (diarrhea, HUS)
• Listeria monocytogenes (listeriosis)
• Clostridium botulinum (botulism)
• Mould toxin (aflatoxin), BSE, virus, parasites
• Chemical Contaminants
• PCBs, dioxins/furans, pesticide residues (DDT),
  mercury
• Food additives nitrites, sulfites (allergy)
• Drugs given to livestock antibiotics, hormones

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78-6 ENVIRONMENT (7)

• Objective
• Describe the steps in an environmental risk
  assessment and be able to critically review a
  simple risk assessment for a community.
• Risk assessment
• Process of evaluating the likelihood of
  occurrence and probable severity of health
  effects due to a hazard
• Done by Occupational health agencies,
  Environmental protection agencies , Public health
  authorities, Clinicians

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78-6 ENVIRONMENT (8)

• Steps in risk assessment
• 1. Hazard identification Is an environmental
  hazard involved? What is it?
• 2. Risk characterization Is the hazard likely to
  cause these types of symptoms in this type of
  patient?
• 3. Exposure assessment Is the patients exposure
  enough to cause these symptoms?
• 4. Risk estimation How much has the hazard
  contributed to the patients condition?
• Source Primer in Population Health

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78-6 ENVIRONMENT (9)

• Hazard Identification
• Agent (based on clinical history see later on)
• Adverse effect
• Target population
• Condition of exposure
• Risk characterisation
• Describe the potential health effects of hazard
• Sources of info scientific literature,
  toxicology or poison center, public health
  department

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78-6 ENVIRONMENT (10)

• Workplace Hazardous Material Information System
  (WHMIS)
• Labeling requirements for hazards
• Indicates availability of Materials Safety Data
  Sheets (MSDS) more details on hazard, how to
  handle it, what to do if emergency
• MSDS are available on the web should find one
  site and bookmark it (Health Canada
  http//www.hc-sc.gc.ca/ewh-semt/occup-travail/whmi
  s-simdut/index-eng.php)

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78-6 ENVIRONMENT (11)

• Exposure assessment
• Characterize exposure of individual or population
• Can be measured directly at times in people (ex
  blood lead level) or in environment
• Estimated most of the time (from history or
  inspection of environment)
• Consultants environmental medicine specialists,
  toxicologists, industrial/occupational hygienists
• Risk estimation
• Probability of being affected and severity of
  effect

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78-6 ENVIRONMENT (12)

• Objective
• - Conduct a focussed clinical assessment of
  exposed persons in order to determine the causal
  linkage between exposure and the clinical
  condition.
• Clues to environmental causes
• Detailed environmental history

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78-6 ENVIRONMENT (13)

• Clues that illness is caused by environmental
  factors
• Patient suspects it
• Pattern of illness atypical (absence of usual
  risk factors, unusual age group, course of
  illness unusual, no response to tx)
• Temporal pattern of illness (weekends/weekdays,
  holidays/home)
• No obvious other cause
• Signs/symptoms suggest specific toxins

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78-6 ENVIRONMENT (14)

• Environmental history - CH20PD2
• Community neighborhood sources of hazard
  industry, waste storage
• Home year of construction, renovations
  materials used in construction and decoration
  moulds garden and house plants use of cleaning
  products, pesticides, herbicides
• Hobbies and leisure exposure to chemicals,
  dusts, or micro-organisms
• Occupation current and previous occupations
  work with known hazards air quality
• Personal habits hygiene products smoking
• Diet sources of food and water cooking methods
  food fads
• Drugs prescription, non-prescription, and
  alternative medications health practices

Source Primer in Population Health
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78-6 ENVIRONMENT (15)

• If a scanning question reveals a possible hazard,
  ask detailed questions to find out as much as
  possible about the nature and level of the hazard
  and then check Time, Place and Person
• Time When did symptoms begin? When did exposure
  begin? When do symptoms get worse? When do they
  improve?
• Place Where is the patient when symptoms get
  worse? Where is the likely hazard? What is the
  channel through which the hazard reaches the
  patient?
• Person Does anyone else have similar symptoms?
  Who? When? Where?

Source Primer in Population Health
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78-6 ENVIRONMENT (16)

• Objective
• Be aware of local, regional, provincial and
  national regulatory agencies that can assist in
  the investigation of environmental concerns
• If evidence supports, or a strong suspicion
  exists for, a causal connection between exposure
  and the clinical presentation, notify the
  appropriate authorities to inspect the site and
  thereafter to decrease and eliminate exposure.

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78-6 ENVIRONMENT (17)

• Environmental Health Jurisdiction
• Public Health Unit
• Enforcement of water and food safety regulations,
  sanitation, local hazard assessment, reportable
  diseases
• Municipal
• Garbage disposal, recycling
• Province/territory
• Toxic waste disposal, air/water standards
• Federal
• Food regulations (Health Canada), designating and
  regulating toxic substances
• International
• Multilateral agreement (Kyoto Protocol)

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78-6 ENVIRONMENT (18)

• Objective
• Describe simple interventions that will be
  effective in reducing environmental exposures and
  risk of disease.
• Examples
• Carbon monoxide CO home detector
• Salmonella well cooked poultry and eggs, safe
  food handling
• Listeria avoidance of unpasteurized cheese for
  pregnant women
• West Nile Virus bug spray
• UV light sunscreen, sunglasses, shade
• Radon ventilation, air exchanger

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78-6 ENVIRONMENT (20)

• Objective
• Communicate simple environmental risk assessment
  information to both patients and the community.
• Important to allow people to understand the risk
  and take action to avoid it
• Elements of communication message, messenger
  (meaning), encoding, channel, decoding, recipient
  (understanding)

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78-6 ENVIRONMENT (19)
WHO, 2002, Global Solar UV Index
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Air Quality Health Index

• New public health information tool developed by
  Health Canada and Environment Canada
• Support decision-making about activity levels
  during increased levels of air pollution.
• Calculated based on
• Ozone (O3) at ground level,
• Particulate Matter (PM2.5/PM10)
• Nitrogen Dioxide (NO2)

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Health Risk Air Quality Health Index At Risk Population General Population
Low Risk 1-3 Enjoy your usual outdoor activities. Ideal air quality for outdoor activities.
Moderate Risk 4-6 Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms. No need to modify your usual outdoor activities unless you experience symptoms such as coughing and throat irritation.
High Risk 7-10 Reduce or reschedule strenuous activities outdoors. Children and the elderly should also take it easy. Consider reducing or rescheduling strenuous activities outdoors if you experience symptoms such as coughing and throat irritation.
Very High Risk Above 10 Avoid strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion. Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation.
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78-6 ENVIRONMENT (21)

• Factors increasing perception of danger
• Characteristics of exposure
• Involuntary not under personal control
• Unnatural unfamiliar
• No trust in institution involved media attention
• Characteristics of outcome
• Catastrophic (not chronic) immediate
  irreversible
• Unknown, uncertain outcome, dreaded outcome
• Affect children or identifiable people
• Source Primer in Population Health

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74-4 WORK-RELATED HEALTH ISSUES

• Key Objective
• Determine whether the work place or environmental
  conditions are potentially hazardous, the impact
  on the health of the workers, and recommend
  preventive strategies.
• Importance in Canada
• 920 work place deaths in 2001
• 373,216 lost-time injuries in 2001

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Work-related Health Issues (2)

• Selected Specific Objectives
• Elicit history of occupation, list of current and
  longest held jobs, exposure to toxic/hazardous
  environments and identify potential relationship
  to patient presentation (temporal relationship to
  work or home activities)
• - Counsel patients about safety issues and report
  findings to affected patients as well as
  employers (considering medical confidentiality
  issues)
• Consider underlying medical conditions and work
  risk

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Work-related Health Issues (3)

• Categories of occupational hazards
• Chemical organic solvents (carbon
  tetrachloride), mineral dusts (silica, asbestos),
  heavy metals, gases, second-hand smoke
• Physical noise, temperature, air pressure,
  radiation
• Biological bacteria, blood
• Mechanical repetitive strain, trauma
• Psychosocial stress

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Work-related Health Issues (4)

• Occupational health history
• Work description and occupational profile
• Prior and current exposure to hazards
• Review of relevant workplace materials safety
  data sheets
• Look for sx of disease job-related injuries
• Temporal relationship between sx and exposure
• Other environments, hobbies, occupation of family
  members (Toronto Notes, 2011)

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Work-related Health Issues (5)

• Under provincial jurisdiction except for 16
  federally regulated industries (e.g. banks,
  airports, highway transport) Canada Labour Code
• 90 of workers are under provincial jurisdiction
• Ontario Occupational Health and Safety Act
• Defines rights of workers
• participate, know, refuse and stop
• Employers have duties to protect health and
  safety
• Enforced by Ministry of Labour (inspectors)

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Work-related Health Issues (6)

• Ontario Workplace Safety and Insurance Act
• Establishes WSIB to oversee work-site
  injuries/disease
• Funded by employers only
• Non-fault protection but no right to sue
• MD must submit medical report to WSIB no need
  for patient waiver.
• MD must report exposure to designated substances
• Asbestos, arsenic, benzene, lead, mercury, vinyl
  chloride, etc.

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Work-related Health Issues (7)

• Occupational Health Program Essential
  responsibilities
• Health evaluation of employees
• Diagnosis/treatment of occup. injuries/illnesses
• Emergency treatment of other injury/illness
• Education of employees re occupational hazards
• Evaluation of programs for the use of indicated
  personal protective devices
• Assist management in providing a safe and
  healthful work environment. Inspect workplace.

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Controlling Occupational Risks
Source
Path
Receiver
Potential approaches to risk control
Modify Redesign Substitute Relocate Enclose
Absorb Block Dilute Ventilate
Enclose Protect Relocate
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Work-related Health Issues (9)

• Work place safety issues can affect family
  members as well as the workers.
• Asbestos
• Causes asbestosis and lung cancer in miners and
  other workers
• Asbestos in the air adheres to work clothing,
  even if the clothes are brushed
• Cleaning of clothes at home liberates asbestos
  fibers and has been shown to cause cancer in
  family members.

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Environmental and occupational health

• Multiple Choice Questionsfor discussion

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• 1) Which one of the following is not a typical
  feature of asbestosis?
• a) increased risk of cancer
• b) pleural thickening and calcification
• c) interstitial fibrosis
• d) obstructive pattern on pulmonary function
  tests
• e) none of the above

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• 3) The following statements regarding noise are
  true EXCEPT
• a) temporary threshold shift recovers following
  cessation of noise exposure
• b) permanent threshold shift is characterized by
  a progressive pattern of hearing loss
• c) most cases of permanent threshold shift are
  surgically treatable
• d) higher frequency noise is more damaging than
  low frequency noise
• e) none of the above

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• 4) The frequencies most necessary for the
  understanding of speech extend from about
• a) 20-20 000 Hz
• b) 400-4 000 Hz
• c) 250-8 000 Hz
• d) 100-5 000 Hz
• e) none of the above

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• 5) Lead exposure typically results in
• a) chronic dermatitis
• b) resting and intention tremor
• c) extensor muscle weakness
• d) arrhythmias
• e) cerebellar ataxia

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• 6) Which of the following statements concerning
  the Workers Compensation Act is true?
• a) the worker reserves the right to sue the
  employer for negligence
• b) funding is provided by the provincial
  government
• c) the worker is guaranteed payment from the
  first day of injury/illness if it is deemed to be
  work-related
• d) the Workers Compensation Board is an
  independent, private agency
• e) none of the above

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• 7) Which of following statements regarding
  radiation is false?
• a) natural background radiation accounts for
  about half of a typical persons exposure
• b) ionizing radiation causes intestinal villi to
  become denuded
• c) exposure to non-ionizing radiation may result
  in cataracts
• d) ionizing radiation results in an increased
  incidence of neoplasia such as lung and thyroid
• e) none of the above

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• 36) All of the following statements concerning
  occupational health are true EXCEPT
• a) disorders of reproduction are among the top 10
  work-related diseases and injuries
• b) most workers are covered by both federal and
  provincial legislation with respect to workplace
  health and safety
• c) skin problems and hearing problems together
  are responsible for half of WCB claims
• d) a complete occupational medical history
  includes investigation of the temporal
  relationship between symptoms and exposure

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• 37) Which of the following statements concerning
  exposure to solvents in the workplace is true?
• a) each solvent compound has a specific antidote
  that can be used to treat exposure
• b) a prominent symptom of solvent exposure is
  memory loss
• c) some solvents can cause skin dryness and loss
  of subcutaneous adipose tissue
• d) solvents do not affect the bone marrow
• e) all of the above

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• 39) All of the following statements about
  environmental health are true EXCEPT
• a) levels of toxic agents measured in the
  environment may not reflect internal organ levels
• b) the federal government monitors the quality
  and types of industrial emissions and toxic waste
  disposal
• c) sick building syndrome is associated with
  Pontiac fever and Legionnaires disease
• d) all humans have detectable levels of PCBs
• e) none of the above is true

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More MCQs

• Here are some more questions that students can
  use to test their own knowledge
• http//www.medicine.uottawa.ca/sim/data/Self-test_
  Qs_Environmental_e.htm
• (The questions contain comments on the answers,
  to illustrate why a given response is not correct)

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Self-test (1)

• Which one of the following gases is NOT
  irritating to the respiratory tract?
• a) ozone
• b) sulfur dioxide
• c) hydrogen chloride
• d) carbon monoxide
• e) chlorine

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Self-test (2)

• How much radiation is an "average Canadian adult
  woman" typically exposed to each year from the
  following sources background dose one screening
  mammography, and one abdominal CT scan?
• a) Background 0.1 Sv mammography 0.5 Sv CT
  1.0 Sv.
• b) Background 1.0 Sv mammography 0.5 Sv CT
  0.1 Sv.
• c) Background 1.0 mSv mammography 50.0 mSv CT
  5.0 mSv.
• d) Background 2.0 mSv mammography 3.0 mSv CT
  10.0 mSv.
• e) Background 1.0 mSv mammography 0.1 mSv CT
  0.1 mSv.

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Self-test (3)

• Toxicokinetics refers to
• a. The speed of distribution of a toxin.
• b. The biochemical and physiological effects of
  toxins.
• c. The diffusion gradient of a toxin.
• d. The activity or fate of toxins in the body
  over a period of time.
• e. The transport of toxins through cell
  membranes.

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