2021 Environmental Health Flashcards
List the environmental health roles for the different jurisdiction (public health unit, muicipal government, provincial and Territorial Government, Federal Government and International )
Public Health Unit
- Enforcement of water and food safety regulations (including restaurant food safety)
- Assessment of local environmental risks
- Monitoring and follow-up of reportable diseases
- Investigation of environmental contamination, clusters of disease
Municipal Government
- Waste disposal, recycling, water and sewage treatment/collection/distribution
Provincial and Territorial Government
- Water and air quality standards
- Industrial emission regulation
- Toxic waste disposal
Federal Government
- Designating and regulating toxic substances
- Regulating food products (e.g. Health Canada (drugs), CFIA)
- Setting policy for pollutants that can travel across provincial boundaries
International
Multilateral agreements (e.g. Kyoto Protocol, UN Convention on Climate Change, International Joint Commission)
Name three ways to categorize Toxicants with an example of each?
- chemical class (e.g., alcohols, heavy metals) 2. source of exposure (e.g., industrial waste, air pollution, food additives) 3. affected organ system (e.g., carcinogen, mutagen)
What do you understand by a Stochastic/random model in a dose-response curve? Give an example?
A Stochastic/random model refers to a Dose vs. risk of outcome; assumes no safe threshold; increased dose increases risk of health outcome of interest (not higher dose therefore bigger tumour) *Non-threshold relationship Generally applies to binary responses EG Cancer - presence of a tumour: yes/no
What do you understand by a Non-stochastic/deterministic model in a dose-response curve? Give an example?
A Non-stochastic/deterministic model refers to a Dose vs. severity of outcome; assumes a threshold; increased dose increases severity of outcome of interest (higher dose results in bigger tumour) *Threshold relationship Generally graded responses EG Sunburn severity
Describe what dose response you see and give an example of what could have this effect?
Hormesis: substance that is beneficial at one concentration but harmful at another concentration
Eg. Fluoride in water (low dose = beneficial for teeth; high dose = skeletal fluorosis = bad)
As the MOH, you learn from your emergency response team that there has been a leak of chlorine gas at the local pool.
What are the human health effects from chlorine exposure?
Acute Effects:
- Irritant – eyes, throat, nose, lungs - cough (less than 1 ppm)
- NOTE – odor threshold is 0.31ppm
- Eye and resp irritation, cough, SOB, headache >1ppm
- SOBb, cough, chest pain, vomiting (30 ppm),
- Toxic pneumonitis, pulmonary edema at high levels (46-60ppm)
- can cause severe burns in humans
· Acute animal tests in rats and mice have shown chlorine to have high acute toxicity via inhalation.
Chronic Effects (Noncancer):
· Eye and throat irritation, and airflow obstruction
· Animal studies: decreased body weight gain, eye and nose irritation, and non-neoplastic lesions and respiratory epithelial hyperplasia from inhalational exposure
· The Reference Dose (RfD) for chlorine is 0.1 milligrams per kilogram body weight per day (mg/kg/d)
Cancer Risk:
· No information is available on the carcinogenic effects of chlorine in humans from inhalation exposure.
· Association between bladder and rectal cancer and chlorination byproducts in drinking water.
Describe the 5 steps in a risk management?
Steps in risk management
- Define the problem and put it in context: Use the risk assessment to define the problem; determine the risk management goals, identify the risk managers with the responsibility and authority to act, and develop a process for engaging stakeholders
- Analyze the risks associated with the problem in context: Consider the nature, probability, and severity of adverse effects on human health or the environment
- Examine options for addressing the risks: Identify and evaluate options for reducing or eliminating risk; assess feasibility, costs, and benefits, as well as legal, social, and cultural impacts
- Make decisions about which options to implement: Base the decision on the best available scientific, economic, and other technical information, consider uncertainty and acceptability of risk (social construct)
- Take actions to implement the decisions (see also: Risk communication) , Conduct an evaluation of the actions
List three disinfection by-products found in drinking water and one health effect associated with each one.
Trihalomethanes - increased risk of cancer; liver, kidney, or CNS problems (formed with chlorine/chloramine and organic/inorganic matter)
- Haloacetic acid - increased risk of cancer (formed with chlorine/chloramine and organic/inorganic matter)
- Bromate - increased risk of cancer (formed with bromide and ozone)
- Chlorite - CNS effects, anemia (formed when chlorine dioxide breaks down)
What two biological systems are primarily affected by lead exposure?
- Blood cells (hematic system) - anemia
- Nervous system - encephalopathy, neuropsychological deficits, especially in children
Name four common air pollutants in the urban environment?
● Ozone
● Particulate Matter
● Carbon Monoxide
● Nitrogen Oxides
● Sulfur Dioxide
● Lead
How would you reduce the risk of high radon gas concentrations in a home?
● Increase the ventilation to allow an exchange of air.
● Seal all cracks and openings in foundation walls and floors, and around pipes and drains.
● Renovate existing basement floors, particularly earth floors.
● Active soil depressurization (usually done by a contractor): preventing radon gas from beneath the home to enter into the interior of the home using a PVC tube and an exhaust fan venting it out to the outdoor air above the home where it quickly dilutes into the atmosphere.
You have been advised that there has been a municipal water breakage and that raw sewage and river surface water may have contaminated the water supply. This occurred 30
minutes ago. The operator says that the chlorine residual did not drop during this timeperiod. Despite this,
a. What two binfectious agents are you still concerned about?
b. What three actions will you take in the next 4 hours to address this issue?
a.Two infectious agents:
• total coliform
• E. coli
b. Three actions:
• Increase disinfectants
• Flush mains
• Consider issuing BWA/DWA
A chemical contaminant was added into bread at a bakery.
List four steps that you would take to reduce the public risk
A.
- Stop the consumption of the bread immediately
Contact schools, community centers and hospitals
- disposal of those still around
- information on product contamination
- if possible, track who may have consumed them
- Risk assessment (consulting with experts - toxicologist - as needed and using environmental PH to assist)
- What was in the chemical? (hazard identification)?
- What are the human health effects – dose response assessment have there been any noted health effects? (vomiting, diarrhoea etc)
- How much would people be exposed to in one slice of bread? (exposure route being oral)
Also consider exposure to cooks in bakery (dermal and inhalation too)
• Characterize the risk
- Risk management
• Once recall done, advise schools, community centres and hospitals to inititate active
surveillance/case finding based on known consumption or expected signs and symptoms
- Identify those who might be most vulnerable to adverse outcomes
- Offer any interventions to mediate risk
- Offer appropriate treatment to reduce risk, if possible
- Reassure if no expected adverse health outcomes
- Education at bakery – consider revoking food license
○ Proper labelling of products
○ Separation of cleaning products from kitchen area
- Communication
- To all stakeholders (internal and external)
- To public – what happened, what we are doing, what individuals who think they consumed the bread should do (ie watch for these symptoms and seek medical care if these things occur)
Recent investigations at the site of a major railway and crude oil explosive disaster have revealed soil and water contamination with hydrocarbons from the fuel spill. There are residential neighborhoods located 500m from the site of the spill, and residents of that neighborhood are concerned that they may have been exposed or may be exposed in the
future to these hydrocarbons. What investigations would you do to find out whether the neighbors are at risk?
Hazard identification is the point of entry. Use the existing epidemiological, toxicological, and experimental evidence.
Looking at any database of toxicological or chemical exposures, we will see that total petroleum
hydrocarbons do have health effects, especially with respect to CNS effects, peripheral neuropathies, hematological cancers, and immunological disorders.
Dose-Response is the next step because (a) it is an important BH criterion for enviro health and
(b) the shape of the dose-response curve will contribute to understanding risk in context.
Variable dose-response effect for different hydrocarbons.
Exposure assessment is population specific, and refers to magnitude, duration, timing and route.
Context specific. May involve biomarker or human samples, and/or environmental sampling.
Risk characterization unites the first three components and includes the context-specific risk,
type of risk, and severity. Should include declarations of uncertainty, limitations and
assumptions. (Context specific)
What are the immediate control measures for confirmed cases of Escherichia Coli O157:H7 infection?
- Education: All cases should be instructed about disease transmission, appropriate personal hygiene, routine practices, and contact precautions.
- Exclusion: All symptomatic and asymptomatic persons who are:
o Food handlers
o Healthcare, daycare or other staff who have contact through serving food with highly susceptible patients or persons in whom an intestinal infection would have
particularly serious consequences
o Those involved in patient care or care of young children, elderly or dependent persons,
o Children attending daycares or similar facilities who are diapered or unable to implement good standards of personal hygiene,
o Older children or adults who are unable to implement good standards of personal hygiene (e.g., mentally or physically challenged)
Exclusion applies until two stool specimens taken from the infected person not less than 24 hours apart and at least 48 hours after normal stools have resumed are reported as negative
What do you understand by a One Health Approach?
Approach that addresses the health of humans, animals, and the environment simultaneously, acknowledging that the health of one impacts on the health of the others (e.g., 60% of infectious diseases in humans are zoonoses)
Name 3 diseases associated with an electromagnetic field exposure (e.g. through living in proximity to a high voltage power line)
- Childhood Leukemia or ALL, acute lymphoblastic leukemia
- testicular cancer and lung cancer
What do you understand by primary and secondary air pollutants? Give an exampe of each
- primary: emitted directly from a source (examples : CO, NH3 (precursor to PM) )
- secondary: forms in the atmosphere (examples03, SO2, PM)
List some limits of the Air Quality Index (AQI)?
- monitoring involves average of continuous measurements q3 hours
- provides info on acute exposure doesn’t take into account long term risk/exposure
- doesn’t take temperature into account (which can affect air quality)
- doesn’t monitor indoor air (even though outdoor air can enter indoors)
- health risks based on mortality data
What do you understand by Sick Building Syndrome?
Definition: Occupants of a building experience acute but non-specific health-related effects that seem to be linked directly to the time spent in the building
- Symptoms (Headache, eye, nose or throat irritation, dry cough, dry or itchy skin, dizziness and nausea, difficulty concentrating, fatigue, sensitivity to odours, rash) that improve when individual leaves the building, but no cause can be identified
- Population-related phenomenon
- Groups of people in a common environment where symptoms occur higher than baseline (ex. compared to CCHS – Canadian Community Health Survey)
- Symptoms > signs
What do you understand by Building-related illness?
Definition: Occupants of a building experience acute and specific health-related effects that seem to be linked directly to the time spent in the buildingSigns and symptoms that are attributable to an identifiable, building-related cause (e.g., Legionnaire’s disease, occupational asthma, hypersensitivity pneumonitis)
Diagnosable at individual level
Using the 6 E framework describe Risk Mitigation for Mould (Persistent dampness and microbial growth on interior surfaces and in building structures)?
-
Engineering
- Management of moisture requires proper control of temperatures and ventilation to avoid excess humidity, condensation on surfaces and excess moisture in material
- Ventilation should be distributed effectively throughout spaces, and stagnant air zones should be avoided
- Repair sources of moisture from outside (e.g., roof leaks) and inside (e.g., plumbing, A/C units)
- Design of building envelope
-
Enforcement
- Building standards and regulations with regard to comfort and health do not sufficiently emphasize requirements for preventing and controlling excess moisture and dampness currently
- Building owners are responsible for providing a healthy workplace or living environment free of excess moisture and mould, by ensuring proper building construction and maintenance; this may be particularly prevalent in poorly maintained housing for low-income people
- Occupants are responsible for managing use of water, heating, ventilation in a manner that does not lead to dampness and mould growth; avoid activities that generate too much humidity (e.g., marijuana grow-ops)
-
Environment
- Wet soils: poor drainage system (flooding), grading, leaf piles, standing water
-
Education
- Control humidity
- Proper ventilation
- Repair all leaks and plumbing problems
- If you have mould, scrub with a detergent, dry quickly & thoroughly, use a disposable dust mask & rubber gloves
-
Empowerment
- Testing: In the absence of exposure limits, tests for the presence of fungi in air cannot be used to assess health risks; 2:1 ratio may show indoor source>outdoor source; may be useful for legal purposes or to show effectiveness of remediation
- Economic
List direct and indirect effects of Climate change?
- Direct effects due to changes in temperature and precipitation, occurrence of heat waves, floods, droughts and fires
- Indirect effects due to ecological disruptions (e.g., crop failures, shifting patterns of disease vectors) or social responses (e.g., displacement of populations due to prolonged drought)
- Until mid-century, climate change will act mainly by exacerbating health problems that already exist and existing diseases (e.g., vector-borne infections) may extend their range into areas that are presently unaffected
- Largest risks will apply in populations that are currently most affected by climate-related diseases (e.g., under-nutrition in areas that are already food insecure such as global South or country foods in Northern Canada)
Lead A) List two most of the most common non-occupational sources of lead exposure for the general population in Canada B) What group in the population is most sensitive to harmful effects of lead? C) What is the most sensitive endpoint of lead toxicity in infants and children? D) What specimen is usually used for monitoring of lead in humans? E) Identify 5 mechanisms by which young children are more susceptible to the harmful effects of lead compared to adults F) List 4 organs or systems that may be affected by chronic lead exposure in humans and identify one effect on each organ system
A) 1. Ingestion of contaminated food 2. Ingestion of contaminated drinking water B) 1. Infants and toddlers C) Reduction of intelligence quotient D) Blood (Blood lead level) E) 1. Greater ingestion of lead due to hand-mouth activity 2. Greater ingestion to body weight ratio 3. Greater absorption in the gastrointestinal tract 4. Blood-brain barrier is still developing 5. Undergoing neurological development 6. More years of life ahead therefore greater time for delayed effects F) 1. Nervous - ataxia 2. Renal/Kidney - reduced GFR 3. Hematological - anemia (hypochromic and normo/microcytic with reticulocytosis) 4. Cardiovascular - hypertension 5. Reproductive - reduced sperm count/fertility https://www.canada.ca/en/health-canada/services/food-nutrition/food-safety/chemical-contaminants/environmental-contaminants/lead.html https://www.atsdr.cdc.gov/csem/csem.asp?csem=34&po=10#:~:text=Lead%20serves%20no%20useful%20purpose,can%20affect%20every%20organ%20system.
Your are a new MOH for a regional health authority and have been advised by the local municipality that the municipal water system at the treatment plant has returned a positive result for total coliforms and negative E. coli. List 5 pieces of information you would seek to inform your actions and recommendations
- What are the current and recent free residual chlorine levels? 2. Have adjacent sites tested positive? 3. Has the contaminated site been retested? 4. What is the level of total coliform? 5. Does this system have a history of prior contamination? 6. Is there any current known gastrointestinal illness outbreak in the community that might be associated with water consumption?
