HSCI 204 FINAL EXAM QUESTIONS WELL ANSWERED LATEST UPDATE 2026

HSCI 204 FINAL EXAM QUESTIONS WELL ANSWERED LATEST UPDATE 2026 Lecture 1- Intro - Answers LECTURE 1 - INTRO Main themes(3) - Answers -hazards usually identified in workers first then communities -most chronic diseases are man-made -identifying and controlling enviro hazards is key to prevention Stages of Epidemiological transition(3) - Answers -the age of pestilence famine -the age of receding pandemics -the age of man-made disease 1st environmental carcinogen - Answers soot -was a short lived issue because we were already moving on to gas and electricity Industrial revolution - Answers coal, petroleum, critical metals The urban penalty - Answers -city children more likely to die because of tenement housing, TB, scrofula Rickets - Answers lack of vitamin D -large city buildings blocked sun -soot blocked sun Asbestos - Answers -fibrosis of the lungs due to inhaling asbestos dust -has a latency period John snow - Answers -broad street pump-cholera -father of epidemiology Epidemiological triangle - Answers -enviro -agent -host Lung cancer epidemic - Answers -cigarettes and air pollution -Dr. alton ocshner: the first anti-smoking crusader during war, smoking became more common -Dr. luther terry concluded that smoking caused cancer -risk factors: tobacco, asbestos, radon, arsenic Lead arsenic and smoking - Answers lead arsenic used to be used in tobacco fields Bradford hill criteria for causation - Answers - strength of association - temporality - coherence Hippocrates - Answers air, water, places Paracelsus - Answers The dose makes the poison Percival potts - Answers 1st carcinogen=soot Lecture 2- health impact of environment hazards - Answers health impacts Quantifying population health - Answers -how many people die of? (count bodies)- limitation: doesnt consider when people die -how many people die of _, at what age, and how long are they disabled by _, how severe is the disability?-limitation: nothing about the cause of death DALY - Answers disability adjusted life year YLL+YLD= one year lost of healthy life YLL - Answers Years of life lost due to premature mortality YLD - Answers years lived with disability; at less than ideal health upstream forces - Answers -much of environmental health is determined by upstream forces -sometimes the link is obvious, sometimes not Global burden of disease - Answers GBD -provides a tool to quantify health loss from disease, injury, risk factors -works to improve health systems -information on upstream and downstream contributers to death and disease To estimate DALYs we need - Answers -exposure -exposure-response relationship -counterfactual -burden estimate for outcome Prevention paradox - Answers -A large number of people at risk may give rise to more cases of disease than a small number at high risk -exposure prevalence is key Odds ratio - Answers risk of outcome in exposed to unexposed Shifting the curve - Answers a cut off of what we consider a disease or disorder A large number of people at small risk - Answers -99% of the world lives in places with unhealthy PM2.5 pollution -47% are still exposed to pollution from household solid fuels -1 in 3 people do not have access to healthy drinking water -2 billion lack basic sanitation Strategies for protecting health - Answers -clinical strategy -population strategy Clinical strategy - Answers physicians diagnose people with signs or symptoms of disease- preferably early on, prescribe a drug or perform a procedure (Downstream) Population Strategy - Answers scientists attempt to identify and reduce upstream risk factors in populations Lecture 3- exposure assessment and enviro epidemiology - Answers Lecture 3 Environmental and occupational health methods - Answers -exposure assessment -epidemiology -toxicology -risk assessment Exposure Assessment - Answers who is exposed, to what, how much, where, how frequently? Exposure assessment(acute and chronic) - Answers -acute: short term bursts of elevated exposure -chronic: longer term periods of exposure (yrs-lifetime), often lower doeses three key ideas of exposure assessment - Answers 1: concentrations vary in time- temporal variation 2: concentrations vary from place to place- spacial variation 3: people move around- what is the concentration where people are and when they are there? exposure assessment methods (2) - Answers -direct methods -indirect methods Direct methods - Answers -personal measurements, biomarkers -can provide a better estimate but expensive and time consuming Indirect methods - Answers -area measurements, questionaires, models -may provide poorer estimates but cheaper and less time consuming Epidemiology - Answers -what effect does the exposure have on human populations -what is the exposure-health relationship -are some groups more susceptable than others -find a link between an exposure and a health outcome Exposure routes - Answers the substance enters the body -dermal -inhalation -ingestion -mother-fetus route will influence how you assess exposure and how you intervene Exposure pathways - Answers the route from the source to the subject -where to intervene? -at the source (the best) -along the exposure pathway -at the household or individual Health impact assessment - Answers -we know that the exposure causes the outcome exposure surveillance - Answers keep track of exposures in groups Identify sources - Answers -when and where people are exposed -where the exposure comes from Controlling exposure - Answers the best way to reduce exposure to a hazard is to produce less of the hazard effect of exposure errors - Answers -exposure estimates can bias epidemiological studies -can cause the exposure-health relationship to be underestimated Epidemiology - Answers the study of the distrobution of determinants of in health related states or events in specified populations and the application of this study to control health problems 3 key ideas - Answers 1- not everyone who is exposed to a hazard will develop the disease of illness 2- not every case of disease or illness is the result of the exposure of intrest 3- correlation does not equal causation Study designs - Answers -cross-sectional -case control -cohort -time series -randomized control trial -natural experiments Randomized control trial - Answers -generally not useful for evaluating diseases with long latency periods -ethical concerns Cohort studies - Answers -identify participants who do not have the disease of intrest, observe them over time to assess new cases of the disease -advantage: less bias, temporal relation -disadvantage: expensive, time consuming Case control study - Answers -opposite to cohort -identify participants based on a disease outcome, the determine who previously had the exposure -advantages: small sample size, can study rare diseases -disadvantages: exposure estimate is difficult Effect estimates - Answers -only tell part of the story -can be wrong -3 categories: confounding, info, selection Prevention - Answers -how should we work to prevent death and disease from enviro hazards -when should we act to prevent disease and death from enviro hazards when should we act - Answers -act too early: waste resources, lose trust -act too late: suffer avoidable death (ex: lead, asbestos) Precautionary principle - Answers -lack of full scientific certainty shall not be used as a reason for post-boning cost-effective measures -should be taken even if some relationships aren't fully established Lecture 4- toxicology and risk assessment - Answers Lecture 4 Toxin - Answers -a compound of natural origin that exerts adverse effects of biological systems -ex: snake venom Toxicant - Answers -a synthetic compound that exerts adverse effects of biological systems Toxicokinetics - Answers -what happens when something enters your body -what happens to a toxic substance- ADME ADME - Answers -absorbtion: toxicant crosses bio barrier -distrobution: toxican is distributed within body -metabolism: most subs undergo metabolic conversion -excretion: urine, feces, exhaled air, breast milk Toxicity effects - Answers -mortality -teratogenicity (birth defect) -carcinogenity -mutagenicity ( heritable DNA changes) -neurotoxixity Toxicity dimensions - Answers -the toxicant of the target organ -does -route of exposure -duration -susceptiility Dose - Answers -the does makes the poison -a non-toxic compound can be toxic at high doses -dose-response relationships (beneficial or toxic) -thresholds -supralinear relationships supralinear - Answers -dose-response relationship -non-linear, decelerating relationship -health risk decreases as exposure increases Timing of exposure - Answers -windows of susceptibility Duration of exposure - Answers acute or chronic matters Measures of toxixity - Answers -lethal dose 50: LD50 -the amount of does of a chemical that produces death in 50% of the population -primary use: comparing acute toxicity -smaller number= more toxic (cause its the amt that causes death) NOAEL - Answers no observed adverse effect level LOAEL - Answers lowest observed adverse effect level regulatory toxicology - Answers 1- non carcinogens (threshold based) 2- carcinogens (linear, no threshold) Threshold-based approacg - Answers -reference dose or acceptable daily intake -sets the acceptable intake at a fraction of the NOAEL to provide a margin of safety Uncertainty factors - Answers -UF's -multiples of 3 or 10 hazard vs risk - Answers -hazard does not equal risk Hazard - Answers something capable of causing an adverse effect risk - Answers the probability that the hazard will cause an adverse effect under specific exposure conditions risk assessment - Answers the process by which hazard, exposure, and risk are determined Risk management - Answers weighing policy alternatives and selecting the most appropriate action IARC - Answers -International agency for research on cancer -evaluates evidence of carcinogenity to put into one of 5 categories 5 IARC categories - Answers 1: carcinogenic to humans 2a: probably 2b: possibly carcinogenic to humans 3: not classifiable as carcinogenic to humans 4: probably not carcinogenic to humans Lecture 5- Air quality - Answers lecture 5 Change in energy sources - Answers -late 1950's coal use decreased as oil increased -gas an heat for power in 1970's outdoor air pollutants - Answers -particulate matter -ozone O2 -sulfur dioxide SO2 -nitrogen oxides carbon monoxide PM sizes - Answers -combustion particles, organic compounds, metals -concentration is typically expressed as the mass of particles in a volume of air Ozone - Answers good up high, bad nearby Traffic air pollution - Answers -mixture of particles and gases that seems to have damaging effects on health Air pollution impacts - Answers - GBD approx 4000 -health Canada approx 15000 deaths air pollution epidemiology - Answers -time series study -chronic exposure studies Harvard six cities study - Answers -cities with a wide range of air pollution -see who lives and who dies -more people died with more air pollution ACS study - Answers -american cancer society -prospective cohort study - PM2.5 risk ratios Non-mortality outcomes - Answers -more severe outcomes usually occur less (vice versa) -differences in significance, interpretation, policy, implications Air pollution and cancer - Answers -outdoor air pollution and particulate matter classified as carcinogenic to humans -effects of air pollution go beyond the lungs Reduction in PM2.5 in pregnancy - Answers -reduced odds of spontaneous abortion -increase in birth weight