-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 non- infectious 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 informationFurther information Types of epidemiology studies Observational: outcomes of risk factors examined. DescriptiveAnalytical Experimental: you have control over risk factors. Randomised Controlled Trial

Descriptive  Collection of data from those affected. -inherent characteristics (e.g. sex, age) -activities (e.g. occupation, drugs, alcohol, leisure) -conditions (e.g. socioeconomic, location) Analytical  Analyse data using a comparison group.  To determine risk factors and establish link between cause and effect. -E.g. Nanna’s mixed berries? smoking and lung cancer.

To establish cause and effect for smoking  1. High relative risk The risk of death from lung cancer is 10 x that for a smoker than a non-smoker.  2. Consistency Different researchers using different populations have come up with the same results.  3. A graded response to a graded dose Death rate increased with the number of cigarettes smoked a day.  4. A time relationship Smoking must precede lung cancer to be caused by it. The rate of smoking has decreased and is reflected in a decrease in lung caner over time.  5. A possible mechanism Chemicals in smoke which are known to be carcinogens- mechanism for mutations in DNA.  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)  5. Long time period  6. Peer reviewed. Some characteristics to identify cause

HSC BIOLOGY EXAMHSC BIOLOGY EXAM Practise with some of these HSC questions.  Short answer Q marks (hard)  Short answer Q marks (ok)  Short answer Q marks (ok)  Short answer Q marks (hard)

From 2007 (ok)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 notesMarking 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.