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Back to Basics, 2016 POPULATION HEALTH Environmental & Occupational Health Marina Afanasyeva MD, MPH, PhD, Public Health & Preventive Medicine PGY4 Based on the previous lectures by Drs. M. Maher, B. Pinard, G. Dunkley, R. Spasoff, and N. Birkett 1 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. © The Medical Council of Canada, 2016 Version Dec 2012 2 MCC Objectives: Population Health 78-6 Environment 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 © The Medical Council of Canada, 2016 Version Dec 2012 3 MCC Objectives: Population Health 78-6 Environment 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. © The Medical Council of Canada, 2016 Version Dec 2012 4 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) March 2016 5 Hazards in Air Physical 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 Air Biological contaminants: • Bacteria: Legionella pneumophila (Legionnaires’ pneumonia, Pontiac fever) • Dust mites (allergies) • Moulds (allergies) • Particulates (pollen, spores) (allergies, asthma) Global warming-related: • Extreme weather (heat waves), change in distribution of vectors of disease, crop failures, etc. 7 Hazards in Water Biological agents: • Viral: Novovirus, hepatitis A virus • 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 Soil Chemical agents: • Pesticides, petroleum hydrocarbons, solvents, motor oil, lead (effects depend on contaminant) • Higher risk: infants/toddlers Biological agents: • Bacteria (tetanus) 9 Hazards in Food Biological Contaminants • Viruses: Norovirus (gastroenteritis; #1 cause), hep A virus • Bacteria: • Campylobacter - raw poultry (diarrhea, maybe bloody) • Salmonella - raw eggs, poultry, meat (diarrhea, maybe bloody) • E. coli - hamburger meat (diarrhea, HUS) • Listeria monocytogenes (listeriosis) • Toxins: Clostridium botulinum (botulism); B. cereus; aflatoxin • Parasites: Cyclospora cayetanesis (fresh fruits and vegetables) • Prions: BSE Chemical Contaminants • PCBs, dioxins/furans, pesticide residues (DDT), mercury • Food additives: nitrites, sulfites (allergy) • Drugs given to livestock: antibiotics, hormones Physical: foreign objects, such as stones, bone fragments, glass, staples 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 Health Risk is the result of the interaction of Hazard, Exposure, and Susceptibility (each component is necessary) Exposure Hazard Risk Susceptibility Individual characteristics Steps in Risk Assessment 1. Hazard identification: Is an environmental hazard involved? What is it? What health problem does it cause? 2. Hazard (risk) characterization: How does it cause these symptoms in this type of patient? – dose-response – toxicology 3. Exposure assessment: Is the patient’s exposure enough to cause these symptoms? Magnitude, frequency, duration, route, etc. 4. Risk estimation: Individual level: How much has the hazard contributed to the patient’s condition? Population level: How much extra risk of the condition in the population is attributable to the exposure? 13 Hazard Identification: Workplace Hazardous Material Information System (WHMIS) Canada's national hazard communication standard; the key elements of the system are • Hazard classification • Labelling of containers • Provision of (material) safety data sheets ((M)SDSs) • • • • • Identification: for the product and supplier Hazards: physical (fire and reactivity) and health Prevention: steps to reduce or prevent exposure, or in an emergency Response: appropriate responses in various situations (e.g., first-aid) http://www.ccohs.ca/oshanswers/chemicals/whmis_ghs/sds.html • Provision of worker education and training programs 14 WHMIS 2015 Uses 9 of These 10 Symbols Except for this 15 Hazard Identification: International Agency for Research on Cancer (IARC) Classification of Carcinogens • Group 1 Carcinogenic to humans (117 agents) – Arsenic, asbestos, benzene, diesel engine exhaust, radon • Group 2A Probably carcinogenic to humans (74 agents) • Group 2B Possibly carcinogenic to humans (287 agents) • Group 3 Not classifiable (503 agents) • Group 4 Probably not carcinogenic to humans (1 agent) Final Step in Risk Assessment: Risk Estimation Probability of harm and the estimate of the magnitude of harm given •this particular exposure •to this particular hazard •in this particular individual (or a group of individuals) 17 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) Adopted from the lecture by Michael A. Trush. 18 Toxicokinetics • What happens to the toxicant! • Time course of toxicants in the body during the processes of absorption, distribution, metabolism (biotransformation), and excretion (clearance) or storage (ADME) • The end result of these toxicokinetic processes is a biologically effective dose of the toxicant • It is a part of the exposure assessment 19 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 hazard characterization 20 Environmental History A part of hazard identification and exposure assessment 21 Clues to Environmental Causes • Clues that illness is caused by environmental factors: – Patient suspects it – Illness pattern is atypical (absent usual risk factors, unusual age group or course, no response to treatment) – Temporal pattern of illness (weekends/weekdays, holidays/home) – No obvious other cause – Signs/symptoms suggest specific agent 22 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; use of PPE • Personal habits: hygiene products; smoking; recreational drugs • Diet: sources of food and water; cooking methods; food fads • Drugs: prescription, non-prescription, and alternative (naturopathic, Ayuverdic); health practices 23 Focused Environmental History • 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? 24 Environmental Health Jurisdiction – Local (or Regional) Public Health • 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 • Health Canada - food regulations, designation and regulation of toxic substances • CFIA (Canadian Food Inspection Agency) – enforcement of regulations • Environment Canada - The Asbestos Mines and Mills Release Regulations – International • Multilateral agreement (Kyoto Protocol) • Whom to ask • Local public health - Ottawa Public Health (613) 580-6744 – environmental exposures • Ontario Ministry of Labour – occupational hazards • Poison Control Centre - specific toxicants • Motherisk – effects on fetus 25 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 26 Risk Communication • Important to allow people to understand the risk and take action to reduce risk • Elements of communication: o Message o Messenger (meaning) o Encoding o Channel o Decoding o Recipient (understanding) 27 Risk Perception: Risk = Hazard + Outrage • 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 28 UV Index WHO, 2002, Global Solar UV Index 29 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 (320-400 nm) and UVB (290-320 nm)) with SPF30 or higher are recommended for individuals performing outdoor work, sports, or recreational activities What is the diagnosis? 31 Air Quality Health Index • 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) 32 Health Risk Low Risk Moderate Risk High Risk Air Quality Health Index General Population Enjoy your usual outdoor activities. Ideal air quality for outdoor activities. 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. 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. Avoid strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion.March 2013 Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation. 33 1-3 > 10 Very High Risk At Risk Population The Lancet 2014 383, 1581-1592 (Copyright @ 2014 Elsevier Ltd) Occupational Medicine 35 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. © The Medical Council of Canada, 2016 Version Feb 2014 36 MCC Objectives Causal Conditions (list not exhaustive) • Ergonomic hazards (mechanical) – e.g. awkward postures and movements, poor lighting; repetitive strain • 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; high demand/low control © The Medical Council of Canada, 2016; version Feb 2014 37 MCC Enabling Objectives Version Feb 2014 Given a worker with a health problem, the candidate will list and interpret critical clinical findings, including: • • • • • • • • • • • • • perform a history and focused physical examination to identify the illness and determine the possible relationship of symptoms to work; identify hazards in the workplace that could have had an impact on the health problem (work and exposure history); identify protective equipment being used and environmental controls that are in place; identify non occupational factors that could influence the condition. list and interpret critical investigations, including: appropriate laboratory or radiologic investigations depending on the presenting health problem (e.g. chest radiography, ultrasound); physiologic and/or functional assessments (e.g. PFTs , audiograms, occupational therapy assessment). construct an effective initial management plan, including: initiate specific therapy as required for the health problem; determine whether the patient should be assigned to a different work, or stop work and advise the patient on this topic; determine follow up care and whether further consultation, counselling and/or a multi-disciplinary approach to care is needed; advise the patient on workers compensation; advise the relevant authorities if necessary (notifiable disease, reporting a dangerous situation). 38 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 enzymes/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; overuse tendinopathies (DeQuervain’s tenosynovitis) Numbness / tingling / altered sensation Fatigue (shiftwork; CO exposure) Allergic reactions and atopy (occupational asthma) Altered hemoglobin levels (anemia in lead poisoning) Syncope and pre-syncopy (heat) 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) • Canada • 920 work place deaths in 2001; 919 in 2014 • 1 of 68 employed workers in 2010 was injured/harmed on the job and received workers compensation as a result 41 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 This material is courtesy of Aaron Thompson, MD, MPH, FRCPC 42 Occupational Health Outcomes •Many chemical and biological exposures can cause allergy resulting in: o Asthma (occupational or work-exacerbated) 18% of asthma is work related If true allergy – sensitizer-induced asthma (vs. irritantinduced asthma) Skin prick testing (immediate hypersensitivity type I) o Allergic contact dermatitis (vs irritant contact dermatitis) Patch testing (delayed hypersensitivity type IV) 43 Occupational Health Outcomes • 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 This material is courtesy of Aaron Thompson, MD, MPH, FRCPC 44 Table 10.5: Some examples of occupational disease Condition Agent Berylliosis Byssinosis Beryllium Cotton dust (numerous agents) Mould in hay Asbestos Farmer’s lung Asbestosis, Mesothelioma Hepatitis A Silicosis Hepatitis A virus Silica dust Example of at risk occupation Aerospace industry Cotton industry Farming Demolition work; ship-building Sewer workers Stone workers 45 Asbestos • Pulmonary fibrosis (asbestosis) – exertional dyspnea and bibasilar end-inspiratory rales • Localized and diffuse pleural thickening, rounded atelectasis, mesothelioma, and lung cancer; may be associated with cancer at 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 (para-occupational disease) 46 Noise-induced hearing loss • High-frequency sensorineural loss • Usually is similar in both ears • Hearing is relatively normal between 250 -1,000 Hz (the loss at the low frequencies rarely exceeds 40 dB) • “Noise notch” between 3000-6000 Hz, typically centered at 4,000 Hz (which rarely exceeds 75 dB) • Recovery at the higher frequencies of 6,000-8,000 Hz • Word recognition is fairly good ( > 75%) 47 48 Work-related health issues: prevention • Primary prevention – Preventing the onset of disease by altering behaviours or exposures that can lead to disease, or by protecting against the effect of exposure to a disease agent – Achieved using hierarchy of controls • Elimination • Substitution • Engineering • Administrative • Personal Protective Equipment (PPE) This material is courtesy of Aaron Thompson, MD, MPH, FRCPC 49 Controlling Occupational Risks Source Path Receiver Potential approaches to risk control Eliminate Modify Redesign Substitute Relocate Enclose Engineering controls: Absorb, block, dilute, ventilate Administrative controls: Regulate exposure duration Enclose Protect Relocate PPE 50 Work-related health issues: prevention • Secondary prevention – Preventing the establishment or progression of a disease – Examples • Screening to detect disease at an early stage when intervention may be more cost-effective • Medical surveillance This material is courtesy of Aaron Thompson, MD, MPH, FRCPC 51 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 This material is courtesy of Aaron Thompson, MD, MPH, FRCPC 52 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 This material is courtesy of Aaron Thompson, MD, MPH, FRCPC 53 1o, 2o, and 3o Prevention Example: Lead Exposed Worker at a Battery Recycling Plant • 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, blood lead level (BLL) • 3o prevention – Chelation if indicated – RTW when BLL acceptable and control measures in place 54 Lead: Exposure History Occupational: manufacturing or use of batteries, pigments, solder, ammunitions, paint, car radiators, cable and wires, some cosmetics, ceramic ware with lead glazes, tin cans • Significant exposures in primary and secondary lead smelting and refinement Hobbies: distillation of "moonshine" alcohol; home repairs; shooting at gun ranges * (bullets have lead, particularly home-made) Lead-glazed tableware and cookware; ceramic dishes (pottery) Ayurvedic medicines *, herbal medications, recreational drugs * Currently the most common causes of increased BLL 55 Lead: Health Effects Blood levels are elevated if ≥ 10 μg/dL = 0.48 μmol/L Main burden in adults is due to • neuro effects (both CNS and PNS) • high BP Short-term (< 1 year) Spontaneous abortion Reduced birth weight Postnatal developmental delay Nonspecific symptoms Neurocognitive deficits Encephalopathy Sperm abnormalities Anemia (basophilic stippling) Colic Additional long-term (> 1 year) Hypertension Nephropathy Peripheral neuropathy Gout 56 Lead: Management • Eliminate the exposure • Education • Chelation is considered if ≥ 50 μg/dL 57 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 ((M)SDSs)) – 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) Based on the material from the lecture by Aaron Thompson, MD, MPH, FRCPC58 Medico-Legal Aspects • 90% of workers are under provincial jurisdiction • 10% of workers are under federal jurisdiction: 16 federallyregulated industries (e.g. banks, airports, highway transport) – under Canada Labour Code • 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 • Compensation is tied to province of work, not province of residence 59 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 (if WSIB requests); no need for patient waiver 60 “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 This material is courtesy of Aaron Thompson, MD, MPH, FRCPC 61 This material is courtesy of Aaron Thompson, MD, MPH, FRCPC 62 Parts of the slide are courtesy of Aaron Thompson, MD, MPH, FRCPC and Richard Wells, Ph.D. CRE-MSD, IWH 63 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/ewhsemt/occup-travail/whmis-simdut/index-eng.php • List of diseases reportable to the medical officer of health (and the reporting form) http://app06.ottawa.ca/online_services/forms/health/support/professionals/communicable_disease/form_en.pdf?redirec= no • Ottawa Public Health 613 580-6744 • List of regulations 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 site http://www.airqualityontario.com/reports/summary.php • Occupational Medicine Specialists of Canada http://www.omsoc.org • Case studies in Environmental Medicine http://www.atsdr.cdc.gov/csem/csem.html • Lange CURRENT Occupational & Environmental Medicine: Fourth Edition Joseph LaDou McGraw Hill Professional, Oct 23, 2006 • • • Call Poison Control Centre for all questions regarding toxicants (you can always ask to speak to a physician – toxicologist) Call and refer patients to Motherisk for all questions regarding exposures during pregnancy 64 Questions about chemical spills – call CANUTEC Environmental and Occupational Health Multiple Choice Questions for discussion 65 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 66 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 67 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 68 Lead exposure typically results in: a) chronic dermatitis b) resting and intention tremor c) extensor muscle weakness d) arrhythmias e) cerebellar ataxia 69 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 70 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 71 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 72 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 73 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 74 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) 75 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 76 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. 77