back to basics, 2013 population health: environmental & occupational health m. maher, md, msc...

Back to Basics, 2013 POPULATION HEALTH:

Environmental & Occupational Health

M. Maher, MD, MSc (PGY5)Epidemiology and Community Medicine

Based on slides prepared by Dr. R. Spasoff and Dr. N. Birkett

1March 2013

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.

2March 2013

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.

3March 2013


• 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)

4March 2013

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)

5March 2013


• 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.

6March 2013

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)7March 2013

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

8March 2013

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

9March 2013


• 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

10March 2013


• 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

11March 2013


• 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/whmis-simdut/index-eng.php)

12March 2013


• 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

13March 2013


• 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

14March 2013


• 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

15March 2013


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

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Source: Primer in Population Health

March 2013


• 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?

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Source: Primer in Population Health

March 2013


• 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.

18March 2013

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)

19March 2013

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

20March 2013


• 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)

21March 2013


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WHO, 2002, Global Solar UV Index

March 2013

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)March 2013 23

March 2013 24

Health Risk Air Quality Health Index

At Risk Population General Population

Low Risk 1-3Enjoy 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 10Avoid 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.


• 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 25March 2013

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

26March 2013

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

27March 2013

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

28March 2013


• 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)

29March 2013


• 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)

30March 2013

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.

31March 2013


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.

32March 2013

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Source Path Receiver

ModifyRedesign

SubstituteRelocateEnclose

AbsorbBlockDilute

Ventilate

EncloseProtect

Relocate

Potential approaches to risk control

Controlling Occupational Risks

March 2013


• 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.

34March 2013

Environmental and occupational health

Multiple Choice Questionsfor discussion

35March 2013

1) Which one of the following is not a typical feature of asbestosis?

a) increased risk of cancerb) pleural thickening and calcificationc) interstitial fibrosisd) obstructive pattern on pulmonary function testse) none of the above

36March 2013

3) The following statements regarding noise are true EXCEPT:a) temporary threshold shift recovers following

cessation of noise exposureb) permanent threshold shift is characterized by a

progressive pattern of hearing lossc) most cases of permanent threshold shift are

surgically treatabled) higher frequency noise is more damaging than

low frequency noisee) none of the above

37March 2013

4) The frequencies most necessary for the understanding of speech extend from about:

a) 20-20 000 Hzb) 400-4 000 Hzc) 250-8 000 Hzd) 100-5 000 Hze) none of the above

38March 2013

5) Lead exposure typically results in:

a) chronic dermatitisb) resting and intention tremorc) extensor muscle weaknessd) arrhythmiase) cerebellar ataxia

39March 2013

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 negligenceb) funding is provided by the provincial governmentc) the worker is guaranteed payment from the first

day of injury/illness if it is deemed to be work-related

d) the Worker’s Compensation Board is an independent, private agency

e) none of the above

40March 2013

7) Which of following statements regarding radiation is false?a) natural background radiation accounts for about

half of a typical person’s exposureb) ionizing radiation causes intestinal villi to

become denudedc) exposure to non-ionizing radiation may result in

cataractsd) ionizing radiation results in an increased

incidence of neoplasia such as lung and thyroide) none of the above

41March 2013

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

42March 2013

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 marrowe) all of the above

43March 2013

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 PCBse) none of the above is true

44March 2013

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)

45March 2013

Self-test (1)

• Which one of the following gases is NOT irritating to the respiratory tract?a) ozoneb) sulfur dioxidec) hydrogen chlorided) carbon monoxidee) chlorine

46

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.

47

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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April 21 March 2013 49

back to basics, 2013 population health: environmental & occupational health m. maher, md, msc...

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