Transcript POPULATION HEALTH: CLINICAL PRESENTATIONS

Back to Basics, 2011
POPULATION HEALTH:
Environmental & Occupational Health
B. Pinard, MD (PGY4)
G. Dunkley, MD
Epidemiology & Community Medicine
Based on slides prepared by Dr. R. Spasoff and Dr. N. Birkett
April 2011
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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
• Ionizing 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:
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•
•
•
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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:
•
•
•
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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:
• SOIL
• Volatile organic compounds (VOC), pesticides, heavy metals, other
waste from industries (effects depend on contaminant)
• Chlorination by-products - trihalomethanes (THM) (cancer)
– 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 patient’s exposure
enough to cause these symptoms?
4. Risk estimation: How much has the hazard
contributed to the patient’s 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.hcsc.gc.ca/ewh-semt/occup-travail/whmis-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 microorganisms
• 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 (19)
WHO, 2002, Global Solar UV Index
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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 (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
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:
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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
April 2011
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 Questions
for 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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2) The following statements regarding contact
dermatitis are true EXCEPT:
a) phototoxic dermatitis following topical
application of creosote requires UV light
b) photoallergic contact dermatitis requires UV
light to be manifested
c) contact eczema involves a type IV delayed
hypersensitivity reaction
d) contact urticaria or hives is a common form of
dermatitis
e) chemical burns by HCl and KOH may result in an
irritant contact dermatitis
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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
Worker’s 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 workrelated
d) the Worker’s 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 person’s 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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8) Which statement concerning vibration
induced white finger disease is false?
a) early symptoms include tingling and numbness
of the fingers when at rest
b) swelling of the fingers over knuckles may be an
early feature
c) cold, damp conditions may precipitate symptoms
d) the affected area eventually spreads to involve
all fingers
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 Legionnaire’s 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/Selftest_Qs_Environmental_e.htm
• (The questions contain comments on the
answers, to illustrate why a given response is
not correct)
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