PHAR 303 Lecture Notes - Lecture 4: Epidemiology Of Cancer, Occupational Disease, Relative Risk
11 May 2018
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Lecture 4: Epidemiology & Toxicology (Jan 18th)
Epidemiology
• The diagnostic discipline of public health
• Overlaps with both toxicology and pathology
• A lot of aspects of diseases when you look at toxicology and epidemiology feeds into
finding out the links between causes and different diseases.
• There are a number of big recent avances in epidemiology
o Branching out from general epidemiology
o Specialty disciplines now including :
▪ Psychosocial
▪ Pharmaco-occupational : problems that occur at different workplaces
▪ Environmental : climate change, pollution
▪ Nutritional : various ways of eating and diseases
▪ Genetic
▪ Molecular
▪ Cancer epidemiology and more
• The study of factors that modify or influence the distribution of diseases or adverse
health effects in a human population – why are these people with a problem and the
rest of them are not
• What are the factors that are the cause of disease
Functions of epidemiology
• Discover the agent, host and environmental factors which affect health
• Determine relative importance of various causes of disease
o →e can’t protect ourselves from every possible toxicants.
o Need to know how toxic a toxicant is.
o Epidemiology can give us relative danger factors, relative risks to make intelligent
decisions about how we should make regulations or how to live our lives.
• Identify high risk populations
o When you look at toxicants, not everybody is equaly succeptible. Some people
can be particulary vulnerable and they can be identified.
• Evaluate effectiveness of current programs, services and regulations
o Ex – different ways to treat water
• Epidemiology is changing and evolving all the time. It is linked to basic sciences and
control the factors linked to public health.
• It can identify people who are at particular risk for one reason or another.
• Assessment and monitoring of the health effects of human exposure to etiologic agents
(usually chemicals) are characterized.
• We use assessment methods to come up with logical analysis of what we are exposed
to and what’s the risk.
Health Risk Assessment Components
Risk Characterization:
1. Identify potential hazard
• What adverse effects does the agent cause?
• Epidemiologic studies
• Toxicological studies
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find more resources at oneclass.com
• Biomedical, medical, physical science and other studies
• The hybridization of both branches as a sub-profession
▪ Is gradually surfacing
▪ Regulatory health laws for health risk assessment; journals
▪ Professionally-related; sharing the same job duties and health
problems/issues.
▪ Need the cooperation to come up with solid information to health agencies
and goverments when they make laws and regulations.
▪ Both are concerned about the causation of ill from different risks.
▪ They have to :
I. Risk Assessment – science based : find the risk
II. Risk Communication – interactive exchange of information & opinions
concerning risks.
Communicate risk from the scientist involved to government
III. Risk Management – policy based
Policies have to be developed based on scientific evidence.
2. Dose-Response Assessment : relationship between the amount you’re exposed to and the
consequences
3. Exposure Assessment: how much the people are exposed to.
In theory, Epidemiology and toxicology communicate with each other
get health risk assessment
affecting public health
In reality, there is communications between all the factors (other than basic science) where
you can have public health announcement, changes in governments..
Public Health approach:
Surveillance – what’s the problem?
Risk Factor Identification – what’s the cause?
Intervention Evaluation – what works?
Implementation – how do you do something about this risk?
We have identified through these 2, some very common risk factors :
- Tobacco smoking risks
- Alcohol consumption risks
- Unhealthy diet
- Physical inactivity
All of these are connected with a huge number of diseases related together.
There are a lot of factors that has to come into account (MONEY). The ultimate decision –
unless is something really drastic – are made by politicians, government agencies. Need
money to make laws or change mandates. The relative risk vs the cost is an important
factor. Making different interventions will cost different amounts of money. Requiring
industries to clean up some of their smoke taxes depend on what kind of industry is can be
douable.. People who make laws are faced with some pressures that the scientist who is
documenting the data is not looking at.
Risk Perception
• The average person is not good at estimate a risk of thing they do or things in the
environment.
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find more resources at oneclass.com
• The risk perceive for any kind of problem are influenced by human psychology.
• If there’s something that you can control and observable, people underestimate the risk
(smoke – people control themselves and it’s observable)
o Controllable, observable - Tobacco Low risk perceived
o Controllable, not observable – HIV
o Uncontrollable, observable – Smog, air pollution
o Uncontrollable, not observable High risk perceived
- They overestimate the danger.
- They always get distressed about the hidden pesticides, very worried.
Not rational.
- →e need studies to help us how we’re going to run our own life and
make pressure on politicians to make regulations.
• A lot of misinformation on the internet
The relationship between your environment, agents and host (you) all have a big impact on
the consequences on what you are exposed to.
Host – Age, sex race, genetics, previous diseases, immune status, religion, customs,
occupation, marital status, family background.
Environment – Temperature, humidity, altitude, crowding, housing, neighborhood, water,
milk, food, radiation, pollution, noise
Agent – Biologic (Bacteria , Virus)
-Chemical (poison, alcohol, smoke)
-Nutritional (lack of, excess)
Burden of disease in 2012 – document world-wide risks of death and disability
• Cardiovascular and circulatory diseases – hypertension
• Exposure to drugs, tobacco, alcohol, diet
• Most of the diseases are lifestyle related problems.
Can get toxicological information from other species
Humans aren’t all genetically identical..
Species differences Human variability we need to do studies on
Kinetics & dynamics Kinetics & dynamics people in order to get
x10 fold variation x10 fold variation meaningful results
→hat’s toxic to humans, often toxic to other species too.
History of Epidemiology
• Hippocrates (400BC) - People knew that things they were exposed to could have an
impact on health, but had no way to study it.
• 1300 – Black death killed half of people in Europe – people realized that it was spreading
with rats along with caravans.
• All sorts of sacrifices, prayers to Gods.
• 1100s Ergot is a fungus that grows on ries and other plants.
o It contains a number of toxins.
o Acute poisoning – convulsions, mania
o Chronic – Gangrene & vasoconstriction in periphery.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Identify high risk populations: when you look at toxicants, not everybody is equaly succeptible. Some people can be particulary vulnerable and they can be identified: evaluate effectiveness of current programs, services and regulations, ex different ways to treat water, epidemiology is changing and evolving all the time. It is linked to basic sciences and control the factors linked to public health. Risk characterization: identify potential hazard, what adverse effects does the agent cause, epidemiologic studies, toxicological studies, biomedical, medical, physical science and other studies, the hybridization of both branches as a sub-profession. Risk communication interactive exchange of information & opinions concerning risks. Communicate risk from the scientist involved to government. Risk management policy based: dose-response assessment : relationship between the amount you"re exposed to and the. Policies have to be developed based on scientific evidence. consequences: exposure assessment: how much the people are exposed to.
