-What is Hepatitis A caused by?
-Symptoms?
-Transmission?
-HOW DO YOU THINK
AUTHORITIES HAVE LINKED
THESE BERRIES TO
HEPATITIS A?
Epidemiology
 Derived from the word epidemic.
 -’ology’ means ‘the study of ’.
 Basically, it is the study of epidemics (includes infectious and noninfectious disease though).
 More specifically, it is the study of the relationship between
incidence and risk factors for diseases in populations.
 All about ‘cause and effect’
 The data can be used to minimise the causes and improve health
of a population.
Lung cancer and smoking:
the history
 Tabacco smoke contains carcinogens.
 An uncontrolled growth of tumours in the lungs.
 Growing tumours destroys lung tissue and breathing
becomes more difficult.
 Lung cancer was rare, until mass production of
cigarettes started and the companies gave them away
for free to soldiers.
 By 1970s lung cancer had gone from rare condition to
number 1 cause of death!
 Once the link between smoking and lung cancer
became more obvious  smoking rates decreased 
lung cancer cases decreased.
Further information
Types of
epidemiology
studies
Observational:
outcomes of
risk factors
examined.
Descriptive
Experimental:
you have
control over
risk factors.
Analytical
Randomised
Controlled
Trial
Descriptive
Analytical
 Collection of data from those
affected.
 Analyse data using a
comparison group.
-inherent characteristics (e.g. sex,
age)
 To determine risk factors
and establish link between
cause and effect.
-activities (e.g. occupation, drugs,
alcohol, leisure)
-conditions (e.g. socioeconomic,
location)
-E.g. Nanna’s mixed berries?
smoking and lung cancer.
To establish cause and
effect for smoking

The risk of death from lung cancer is 10
x that for a smoker than a non-smoker.

Some characteristics to
identify cause
1. High relative risk
2. Consistency
Different researchers using different
populations have come up with the
same results.

3. A graded response to a graded
dose

1. Large sample size

2. Control of variables (e.g. age, race,
gender)

3. Data that is collected (e.g. lifestyle,
environment, morbidity and mortality rate)


4. Data analysis (e.g. compare for common
data with and without disease and in
people with disease)
Smoking must precede lung cancer to be
caused by it.

5. Long time period
The rate of smoking has decreased and
is reflected in a decrease in lung caner
over time.

6. Peer reviewed.
Death rate increased with the number
of cigarettes smoked a day.

4. A time relationship
5. A possible mechanism
Chemicals in smoke which are known
to be carcinogens- mechanism for
mutations in DNA.
HSC BIOLOGY EXAM
Practise with some of these HSC questions.
 2012. Short answer Q 26. 5 marks (hard)
 2011. Short answer Q 27. 4 marks (ok)
 2007. Short answer Q 25. 3 marks (ok)
 2006. Short answer Q 27. 5 marks (hard)
From 2007 (ok)
 Epidemiology studies indicate that there is a
relationship between smoking and the incidence of
lung cancer.
 What information would have been gathered to
establish this relationship?
(3 marks)
Marking notes
 In better responses candidates identified
characteristics of a sound epidemiology study and
linked this to the need to establish a relationship
between smoking and lung cancer.