back to basics, 2015 population health: environmental & occupational health marina afanasyeva,...

Back to Basics, 2015

POPULATION HEALTH:

Environmental & Occupational Health

Marina Afanasyeva, MD, MPH, PhD (PGY3)Public Health & Preventive Medicine

Residency Program

1Based on the previous lectures by Drs. M. Maher, B. Pinard, G. Dunkley, R. Spasoff, and N. Birkett

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 and allied health professionals (e.g., occupational hygienists), where appropriate, to help implement the necessary interventions to prevent future illness. Physician involvement is important in the promotion of global environmental health.

2© The Medical Council of Canada, 2015


Key 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.

•Communicate with patients, communities, and employers, where appropriate, concerning environmental risk assessment



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.


Environmental Hazards

• 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)

5March 2015

Hazards in AirPhysical contaminants

• Radiation: Radon (lung cancer), UV (skin cancer)• Sound waves (hearing loss)

Chemical contaminants• Ozone at ground level (worsens asthma)• Sulphur dioxide (SO2); nitrogen dioxide (NO2)

(respiratory irritants)• Carbon monoxide (CO) (asphyxiation, headache)• Organic compounds: benzene (carcinogen – leukemia)• Second-hand tobacco smoke (lung cancer)• Heavy metals; industrial emissions

6

Hazards in AirBiological contaminants:

• Bacteria: Legionella pneumophila (Legionnaires’ pneumonia, Pontiac fever)

• Dust mites (upper and lower-airway Sx)• Moulds (allergies)• Particulates (pollen, spores, aerosols) (allergies,

asthma)

Global warming-related: • Extreme weather (heat waves), change in distribution

of vectors of disease, crop failures, etc.

7

Hazards in WaterBiological agents:

• Bacteria: E. coli, Salmonella, Pseudomonas• Protozoa (cysts): Giardia, Cryptosporidium (GI

symptoms 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)

8

Hazards in SoilChemical agents:

• Pesticides, petroleum hydrocarbons, solvents, motor oil, lead (effects depend on contaminant)

• Higher risk: infants/toddlers

Biological agents: • Bacteria (tetanus)

9

Hazards in FoodBiological Contaminants

• Norovirus (gastroenteritis)• Campylobacter - raw poultry (diarrhea, maybe bloody)• Salmonella - raw eggs, poultry, meat (diarrhea, maybe

bloody)• E. coli - hamburger meat (diarrhea, HUS)• Listeria monocytogenes (listeriosis)• Clostridium botulinum (botulism)• Parasites; aflatoxin; prions (BSE)

Chemical Contaminants• PCBs, dioxins/furans, pesticide residues (DDT), mercury• Food additives: nitrites, sulfites (allergy) • Drugs given to livestock: antibiotics, hormones

10

Environmental 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

11

Hazard Exposure

Risk

SusceptibilityIndividual characteristics

Health Risk: The interaction of Hazard, Exposure, and Susceptibility (3 necessary components)

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?

13

Steps in Risk Assessment (II)• Hazard Identification:

Is an environmental hazard involved? What is it?–Identified the agent capable of causing –Adverse effects–in the susceptible target population –Under certain condition of exposure–Involves a thorough environmental Hx (to be discussed)

• Risk characterisation: Can this hazard cause these symptoms?–Describe the potential health effects of hazard –Sources of info: scientific literature, toxicology or poison center, public health department

14

Risk Characterisation• 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)

15

Exposure Assessment (of individual or population)

Estimated from history (most of the time) and/or inspection of environment

Measured directly (sometimes)– in environment– In human samples (blood lead level)

Affected by route, site, duration, frequency

Consultants: environmental medicine specialists (eg. at Public Health Ontario), toxicologists, industrial/occupational hygienists (eg. at the Ministry of Labor, see http://www.crboh.ca)

17

Final Step in Risk Assessment: Risk Estimation

Probability of a health effect and its severity

18

Dosis facit venenum• What is there that is

not poison? All things are poison and nothing without poison. Solely, the dose determines that a thing is not a poison.

– Paracelsus (1493-1541)

19Adopted from the lecture by Michael A. Trush.

Toxicokinetics

• What happens to the toxin!• Time course of toxicants in the body during the

processes of absorption, distribution, biotransformation, and excretion (or storage) or clearance.

• The end result of these toxicokinetic processes is a biologically effective dose of the toxicant.

• It is a part of the exposure assessment

20

Toxicodynamics

• What happens to the human body!• The molecular, biochemical, and physiological

effects of toxicants or their metabolites in biological systems

• It is a part of the risk estimation

21

Focused Environmental History

Clues to environmental causes Detailed environmental history

A part of hazard identification and exposure assessment

22

Clues to Environmental Causes

• 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

23

CH20PD2

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; longest occupation; 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

24

• If a scanning question reveals a possible hazard, ask detailed questions about the nature and level of the hazard and then check:

• 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?

25

Focused Environmental History

Regulatory Agencies

• If evidence or a strong suspicion exist 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.

26

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• Ontario Ministry of the Environment (monitors air quality across ON)

– Federal• Food regulations (Health Canada), designating and regulating toxic substances• The Asbestos Mines and Mills Release Regulations (Environment Canada)

– International• Multilateral agreement (Kyoto Protocol)

• When in doubt who to ask, contact your local public health unit. • Ottawa Public Health (613) 580-6744

27

Risk management• Interventions to reduce environmental exposures:

– 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, hat, long sleeves– Radon: ventilation, air exchanger, radon test kits

28

Risk Communication

•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)

29

Risk Communication

• 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

30

UV Index

31

WHO, 2002, Global Solar UV Index

UV Index Specifics• The UV Index that is reported as part of the weather forecast is the highest

expected value for the day• UV rays can cause sunburns, eye cataracts, skin aging, and skin cancer (SCC; BCC;

melanoma)• Highest in the early afternoon (about 1:30 PM Eastern Daylight Saving Time in

Southern Ontario) and during the months of June and July• Avoid the mid-day sun (between 11 AM and 4 PM)• If you must be outside, seek shade, wear sunglasses, use sunscreen, if possible

cover up with lightweight clothing and wear a hat• Sunscreen products with SPF 15 are recommended for daily use • Broad spectrum products (protective against UVA and UVB) with SPF30 or higher

are recommended for individuals performing outdoor work, sports, or recreational activities

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)34

March 2013 35

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.

Occupational Medicine

36

MCC Objectives: 78-8 Work-Related Health Issues• Key Objective: • Given a patient with a health problem, the candidate

will evaluate the possible workplace etiological factors, to assess the contribution of occupational exposures for the most common pathologies, to assess the impact of the condition on the ability to work, and develop an appropriate management plan. Particular attention should be paid to the identification of occupational risks for the patient and his/her co-workers.


MCC Objectives

Causal Conditions (list not exhaustive)•Ergonomic hazards

– e.g. awkward postures and movements, poor lighting

•Chemical hazards – e.g. organic solvents, metals, asbestos, toxic gases

•Physical hazards – e.g. noise, vibration, radiation

•Biological hazards – e.g. blood or other body fluids, animal and bird droppings

•Psychological and work organization hazards – e.g. workplace stressors, workplace bullying


Occupational Medicine (OM) in MCCQE Part 1

• As a primary question

• Integrated into options for other questions

• Think about classic occupational skin and lung issues

• Also think about other domains in which OM can play a role, such as psychiatry, and also specific conditions which have occupational causality such as abnormal liver function tests, fatigue, hypertension etc.

• For a sampling of “hot topics” in OM, go to the Scientific American website and type Occupational Medicine in the search box

Types of clinical scenarios that may involve occupational exposure

• Cough• Hand and wrist injuries• Numbness / tingling / altered sensation• Fatigue• Allergic reactions and atopy• Altered hemoglobin levels• Syncope and pre-syncopy• Dysmenorrhea• Proteinuria• Sleep disorders• Bone or joint injury• Back pain• Neck pain • Poisoning• Prenatal Care

40

Occupational Health as a Public Health Concern

•Most of the world’s population (58%) spend 1/3 of their adult life at work (WHO 1994)

•In Canada• 920 work place deaths in 2001• 373,216 lost-time injuries in 2001• 1 of 68 employed workers in 2010 was injured or harmed on the job

and received workers compensation as a result.

41

Categories of occupational hazards1. Physical: heat, cold, vibration, noise, air

pressure, radiation2. Chemical: organic solvents (carbon

tetrachloride), mineral dusts (silica, asbestos), heavy metals, gases,

pesticides, second-hand smoke3. Biological: bacteria, viruses (exposure to blood),

mold4. Ergonomic (mechanical):

force, posture, repetitive strain5. Psychosocial: psychotraumatic events, high demand

low control, lack of supportAll impact upon the well-being, working capacity and even the life span of working individuals

42

Occupational Health Outcomes

•The most significant chemical exposures tend to be solvents and heavy metals:

– Most solvents cause CNS depression, irritation and dermatitis

– Some solvents causes PNS, hepatic and/or renal toxicity

– Heavy metals primarily cause CNS, PNS, haem, and renal toxicity

43This material is courtesy of Aaron Thompson, MD, MPH, FRCPC


•Many chemical and biological exposures can cause allergy resulting in:

– Asthma

– Allergic Contact Dermatitis



•Approximately 10% of all cancers are occupational

– Common occupational cancers are lung, bladder, and mesothelioma

– Common occupational carcinogens are asbestos, polyaromatic hydrocarbons (PAHs), and aromatic amines


Asbestos• Pulmonary fibrosis (asbestosis) – exertional dyspnea and

bibasilar end-inspiratory rales • Pleural abnormalities (localized and diffuse pleural

thickening, rounded atelectasis), mesothelioma, and lung cancer, and it may be associated with cancer at some extra-thoracic sites

• Most important route of exposure is inhalation • Miners, shipbuilding facility workers, demolition worker• 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

46

Work-related health issues: prevention• Primary prevention

– Preventing the onset of disease by altering behaviours or exposures that can lead to disease, or by protection against the effect of exposure to a disease agent

– Achieved using hierarchy of controls• Elimination• Substitution• Engineering• Administrative• Personal Protective Equipment


48

Source Path Receiver

ModifyRedesign

SubstituteRelocateEnclose

AbsorbBlockDilute

Ventilate

EncloseProtect

Relocate

Potential approaches to risk control

Controlling Occupational Risks

Work-related health issues: prevention

• Secondary prevention– Preventing the establishment or progression of a

disease once a person has been exposed to it. Examples: early detection via screening procedures that detect disease at an early stage when intervention may be more cost-effective

– Examples• Medical Surveillance• Screening


Work-related health issues: prevention

• Tertiary prevention– Preventing the return of a disease that has been

treated in its acute phase. It seeks to limit or delay the impact caused by the disease on the patient’s function, longevity, and quality of life.

– Examples• Disability management• Return to work


Work-related health issues: prevention• 1o prevention

– Minimize Exposure, prevent Outcome– Approach using hierarchy of controls

• 2o prevention– Early detection of Outcome– Screening, surveillance

• 3o prevention– Mitigate effects of Outcome– RTW +/- accomodation once effectively treated and controls

have been put into place to prevent recurrence


1o, 2o, and 3o PreventionExample: Lead Exposed Worker

• 1o prevention– Substitute tin for lead– Enclose process, increase ventilation– Optimize hygiene – no eating/drinking/smoking, separate clothes,

shower post shift, housekeeping– Fit tested lead cartridge respirator

• 2o prevention– Surveillance: annual Hx, physical, CBC, BLL, zinc protoporphyrin (ZPP)

• 3o prevention– Chelation if indicated– RTW when BLL acceptable and control measures in place

52

Occupational Health Conditions:

Clinical Assessment and Management

• Confirm diagnosis, then address work relatedness– Work description and occupational profile– Prior and current exposure to hazards– Review of relevant workplace materials safety data sheets

(MSDSs)– Depending on the condition, there are various objective

means to determine work relatedness• Prescribing return to work (with restrictions if necessary) is

part of the treatment plan• If unsure, refer! (Occupational Medicine Specialist)

53Based on the material from the lecture by Aaron Thompson, MD, MPH, FRCPC

Medico-Legal Aspects• 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– Enforced by Ministry of Labour (inspectors)– Employers

• must protect health and safety • report workplace illnesses and injuries• accommodate injured/ill workers • pay cost of injury, illness

54

Workplace Safety and Insurance Act (Ontario)

– 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

55

“Duties” of the treating physician– Treat worker and assist in RTW process

– File Worker’s Compensation claims

– Report to Ministry of Labour if designated substance has resulted in disability

– CMA Policy 2000• Be knowledgeable of workplace• Draft clear recommendations• Make use of available occupational health resources

– Occupational Health Physician assumes lead in advising on RTW/accommodation


58Parts of the slide are courtesy of Aaron Thompson, MD, MPH, FRCPC and Richard Wells, Ph.D. CRE-MSD, IWH

Environmental and Occupational Health

Multiple Choice Questionsfor discussion

59

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

60

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

61

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

62

Lead exposure typically results in:

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

63

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

64

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

65

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

66

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

67

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

68

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)

69

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

70

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.

71

Resources for your practice• 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)

• List of disease reportable to the medical officer of health https://app06.ottawa.ca/online_services/forms/health/support/professionals/communicable_disease/form_en.pdf

• Ottawa Public Health 613 580-6744

• List of regulation by Environment Canada http://ec.gc.ca/lcpe-cepa/eng/regulations/detailReg.cfm?intReg=56

• Check your local AQI and refer your patients to this sitehttp://www.airqualityontario.com/reports/summary.php

• Occupational Medicine Specialists of Canada http://www.omsoc.org

• Case studies in Evironmental Medicine http://www.atsdr.cdc.gov/csem/csem.html

• Lange CURRENT Occupational & Environmental Medicine: Fourth Edition Joseph LaDou McGraw Hill Professional, Oct 23, 2006

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back to basics, 2015 population health: environmental & occupational health marina afanasyeva,...

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