Evaluate the epidemiological and experimental evidence linking cigarette smoking to disease and early death.
By Jed Spree and Kat Paton
Epidemiology is the study of disease in populations and of the various factors that appear to affect who has the disease. Epidemiological evidence is the evidence that comes from trends we see in large bulks of data collected from epidemiology. Large bulks of data are needed as epidemiological evidence does not usually take account of many control variables, as they are difficult control. Epidemiological evidence about smoking is shown below.
Experimental evidence is a bit different as full on laboratory research is difficult with people, especially with long term experiments such as the effects of smoking. However it has been done on cultures of human cells or animals. In the 1960's experiments were carried out on beagles (dogs), which were made to inhale cigarette smoke to find out if this increased their risk of developing lung cancer (image shown above). It did.
Research into the health risks of smoking has been ongoing since the 1950s and it all supports the hypothesis that smoking causes diseases such as lung cancer, coronary heart disease and strokes. Scientific and medical advances have allowed us to identify specific health conditions that are directly caused by smoking.
In the exam, it is likely that you will be given data that needs interpreting.An example of how to answer those kinds of questions is shown below:
- Describe the data - The graph shows that the risk of lung cancer increases as the number of cigarettes smoked per day increases. Fewer non-smokers developed lung cancer compared with heavy smokers.
- Draw a conclusion - The graph shows a positive correlation between the number of cigarettes smoked a day and the risk of developing lung cancer. Although they seem to be linked, the graph is insufficient for you to be definite. For example, heavy smokers may also drink more, which could cause the increased risk of lung cancer.
- Evaluate the study - You may also be given details about the study that produced the given results and then asked to evaluate them. The larger the sample size, the more reliable your results will be. However, the reliability of the results may be reduced by the fact that many people lie when taking questionnaires, especially ones regarding their health. It is also better for the sample to be made up of a variety of people from different age groups, gender and backgrounds to minimise the chances of the data being bias.
Questions (if you want)
^From the June 2012 exam paper.
^From the June 2011 exam paper.