Lecture 7 - Epidemiology

Question 1

Risk Perception

Answer 1

Smoke: controlable, observeable
HIV: controllable but non-observable
Smog/pollution: uncontrollable but observable
Pesticides: uncontrollable and unobservable
People say uncontrollable and unobsevable are most dangerous when really controllable and observable toxins are most dangerous=SMOKING

Question 2

Lancet Study on the Burden of Disease

Answer 2

-huge study that identified 20 leading risk factors to disease
Major cause was hypertension
In terms of tox:
2--> tobacco
3--> alcohol 
4-->household pollutions
Thus toxicant expsoure is important

Question 3

The Black Death (1300)

Answer 3

-killed 50% people, lasted few years, RATS
Ergot fungus was teh cause; grew on rye
Acute High dose: convulsions, mania, halluciamntions
Chronic low dose: gangrene due to peripheral vasoconstriction
“St Anthony’s Fire”

Question 4

Chimney sweeps

Answer 4

1775: higher incidence of scrotal cancer
Soon: had to bathe at every shift

Question 5

Cholera

Answer 5

1854
Due to water contamination in certain London villages
When well was closed, cholera diseappeared

Question 6

Great Smog of London

Answer 6

-they were burning coal in fireplace; rose up and caused severe pollution
4000 deaths and many more after
What is in air? Suflur dioxide, co2, NO
—> excess deathwas duel to suflur dioxide. The coal was low quality with high suflur content
SO2 is a airway irritant and NO as well
CO2 is an asphyxiant

Question 7

Framingham Heart Study

Answer 7

Prospective cohort study
>1 risk factor can go from 5-50%
Understands risk factors in CVS disease

Question 8

Methods to evaluate toxins

Answer 8

Case control: outcome –> expsoure (you have the disease already)
Cohort: exposure –> outcome
Ex: Framingham study: follow people in life exposed to same factors, diet etc, and saw that the outcome was heart disease

Question 9

Odds ratio

Answer 9

For case control study
The ratio os risk of disease in exposed vs unexposed
OR=2: exposed had 2x the risk as unexposed

Question 10

Standardized Mortality Ratio

Answer 10

Like odds ratio (exposed/unexposed) but now its risk of death, NOT disease
SMR=150 –> 50% higher chance of death due to thsi exposure

Question 11

Relative Risk

Answer 11

Ratio of disease in exposed/unexposed population

RR=175 –> 75% increase in risk

Question 12

1948 Study on Chula Vista Landfill and Greenwood Landfill

Answer 12

Study on 2 diff landfills and the health of the population living thereall kinds of chemicals dumped there

1950: houses built over it
1995: concluded no correlation b/w landfill areas and disease

Question 13

Hierarchy of Data

Answer 13

Meta-analysis (systematic review) > randomized trials > cohort > case-control > cross-sectional

Question 14

Study: the effect of diesel exhaust in miners

Answer 14

-retrospective cohort study (as opposed to Framingham=prospective)
Comparing workers exposed and not exposed to diesel exhaust
====> lung cancer
Case control study showed non-smokers with highest expsoure 7x mor likely to die
Cohort study showed lung cancer among exposed group was 5x higher
THIS ALLOWED DIESEL EXAHSUDT TO CLASSIFY AS HUMAN CARCINOGEN