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9.4 Search for better health: 6. Epidemiological Studies

Syllabus reference (October 2002 version)
6. Epidemiological studies involve the collection and careful statistical analysis of large quantities of data. Such studies assist the causal identification of non-infectious diseases	Students learn to: identify and describe the main features of epidemiology using lung cancer as an example   identify causes of non-infectious disease using an example from each of the following categories: inherited diseases nutritional deficiencies environmental diseases	Students: gather, process and analyse information to identify the cause and effect relationship of smoking and lung cancer   identify data sources, plan and perform a first-hand investigation or gather information from secondary sources to analyse and present information about the occurrence, symptoms, cause, treatment/management of a named non-infectious disease

Extract from Biology Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW

[Edit: 12 Jun 08]

Prior learning:

Science Stages 4 - 5 syllabus: Outcome 5.8 (content 5.8.2 e; 5.8.4 b).

gather, process and analyse information to identify the cause and effect relationship of smoking and lung cancer

• Use the Internet to gather information on lung cancer. Make sure the information provides examples of or discusses the results of epidemiological studies.
  Lung cancer Cancer council of New South Wales
• Process the information to identify statistics that can be used to demonstrate a possible link between cause and effect for the disease chosen.
• Analyse the information to decide how the cause and effect relationships demonstrated in epidemiological studies can be used to identify the cause of the disease.

  Deaths due to smoking in NSW NSW Health Department

  Lung cancer in women Cancer council of New South Wales
  
  Causes of death NSW Health Department

identify and describe the main features of epidemiology using lung cancer as an example

• Epidemiological studies need to investigate cause and effects of a disease. To be valid they must:
  • focus on large groups of people rather than individuals and relate to a target population that can be identified. This allows statistics to be used to identify trends and possible causative factors.
  • use populations where there is occurrence of the disease and where there are unequal exposures to the suspected or possible causes. No conclusions about the effect of smoking could be drawn from a group of people who each smoke 20 cigarettes a day
  • allow for analysis of factors that might contribute to the occurrence of the disease among those afflicted, such as age, sex, ethnic group, and occupation.
     
• Trends in lung cancer NSW Health Department, seem to reflect smoking habits. A general decline in the incidence and mortality rates in males is attributed to decreased tobacco smoking among men.

identify causes of non-infectious disease using an example from each of the following categories:

• inherited diseases
• nutritional deficiencies
• environmental diseases

Inherited diseases

• Inherited diseases result from mutations that lead to the production of different or faulty enzymes, resulting in impaired body function.
   
  Examples
  
  Examples of inherited diseases are Down syndrome, colour blindness, haemophilia, phenylketonuria, thalassaemia and sickle cell anaemia.
  
   
• Down syndrome is an inherited disease that is caused by the non-disjunction of chromosome 21. This results in three chromosomes and not the usual two (trisomy 21). People with Down syndrome have a characteristic appearance and may have a shortened life span. Mothers who have children later in life are more prone to produce Down syndrome children.

  Down syndrome Dr. Len Leshin, pediatrician, Corpus Christi, Texas, USA
  

Nutritional deficiencies

• The effect of nutritional deficiencies depends on the kind of deficiency. In some parts of the world diets may be deficient in certain elements, such as iodine, copper, iron or zinc.
   
  Examples
  
  Examples of nutritional diseases are scurvy, rickets, goitre, kwashiorkor and beri beri.
  
  
• Scurvy is caused by a deficiency in vitamin C. Symptoms include bleeding gums and tooth loss. It is treated by increasing the intake of food and drinks containing vitamin C, such as citrus fruit.

  Scurvy Wikipedia, The free encyclopedia

• Rickets is a metabolic bone disease resulting from a deficiency of Vitamin D. This can be due to a lack of sufficient vitamin D in the diet or due to insufficient exposure to sunlight. The disease is called osteomalacia when it occurs in adults.

  Rickets Emory Healthcare, Atlanta, Georgia, USA

Environmental diseases

• Environmentally caused diseases include those due to lifestyle, such as smoking-related diseases, as well as those caused by something in the environment, such as lead or substances that cause allergies.
   
  Examples
  
  Examples of environmental diseases include smoking-related diseases, Minamata disease, lead or asbestos related diseases and melanoma.
  
• Mesothelioma is caused by exposure to asbestos and patients don't get any symptoms until 20 to 30 years after exposure. There is no cure and treatment can only slow down the progression of the disease.

  Mesothelioma Better Health Channel, Department of Human Services, Victorian Government

• Minamata disease causes deformity and mental retardation in a foetus. It is a result of high levels of methyl mercury in the food chain.

  Minamata disease University of Pittsburgh, USA

identify data sources, plan and perform a first hand investigation or gather information from secondary sources to analyse and present information about the occurrence, symptoms, cause, treatment/management of a named non-infectious disease

If you know someone with a non-infectious diseases, you could ask their permission to interview them and then carry out a first-hand investigation of the disease.

• If this is the case, begin by determining the type of data that needs to be collected through interview and what information you may need to collect from secondary sources. Consider how you might analyse the information to make it useful in generalising about the occurrence, symptoms, cause and treatment or management of the disease.
• Plan your investigation so that valid and reliable information is collected. You may need to research some issues from secondary sources, particularly if your subject is uncertain about particular aspects required.
• Perform your investigation by conducting the interviews and compiling a report. You could summarise your findings in a table format, like the one below.

If you complete this syllabus point using secondary sources, you could:

• choose a non-infectious disease from one of the categories listed in the previous section.
• gather information from a range of resources, including popular scientific journals, digital technologies like CD-ROMs and the Internet.
• analyse the information to make a generalisation for each of the factors being examined.
• present a summary using a table like the one below.
  
  

  Name of disease
  Occurrence
  Symptoms
  Cause
  Treatment or management