Self-Assessment Questions (SAQs) for Study Session 2
Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering these questions.
SAQ 2.1 (tests Learning Outcome 2.1)
Match the following words to their correct definitions.
Using the following two lists, match each numbered item with the correct letter.
vector
faecal sludge
greywater
pathogen
blackwater
a.disease-causing agent
b.wastewater containing human excreta
c.sludge that builds up in pit latrines and septic tanks
d.used water from domestic washing, food preparation, etc.
e.organism that transmits disease
- 1 = e
- 2 = c
- 3 = d
- 4 = a
- 5 = b
SAQ 2.2 (tests Learning Outcome 2.2)
Which of the following statements are false? In each case explain why it is incorrect.
- A.Exhaust gases from industries and motor vehicles are major causes of air pollution.
- B.Medical wastes should be collected and disposed of with normal household waste.
- C.Organic solid waste from households, cafeterias and restaurants provide breeding places for pathogens and vectors.
- D.Faeces are an environmental pollutant when left in the open, as in the case of flying toilets.
- E.Industrial wastewater can cause water pollution if discharged directly into a river but is safe to spread over bare ground.
Answer
B is false. Medical waste should not be handled with normal household waste. It needs special disposal because it may contain hazardous substances including body fluids from patients, pharmaceutical chemicals and sharp objects such as needles.
E is false. Industrial wastewater can cause water pollution if discharged into a river but can also pollute soil and groundwater if spread over the ground.
SAQ 2.3 (tests Learning Outcome 2.2)
By what route do pollutants get into rivers and other surface waters?
Answer
Contaminants can flow directly into surface water sources, such as rivers, from pipes and drainage channels, e.g. industrial wastewater from a factory. They may also enter rivers in rainwater run-off that has washed over surrounding land and collected pollutants from any wastes discarded there, including faeces. Another possible route is from groundwater. If groundwater in the area has become contaminated, this may seep out into the river. You may also have thought of direct contamination from activities in the river water such as cleaning dirty vehicles.
SAQ 2.4 (tests Learning Outcomes 2.3 and 2.4)
What are the major health risks from:
- a.open defecation
- b.allowing food waste and litter to accumulate in a ditch
- c.not washing hands before eating.
Briefly explain how these risks could be reduced.
Answer
- a.If faeces are deposited in open areas then pathogens can be washed into rivers and groundwater (see answer to SAQ 2.3). Also flies are likely to transfer pathogens from faeces onto food. Many diseases are caused by ingesting contaminated food or water, including diarrhoea, dysentery, cholera, typhoid, and infection by intestinal worms and other parasites.
These problems could be reduced by providing sufficient numbers of well-designed and maintained latrines so that people did not have to defecate in the open.
- b.If food and other organic waste is allowed to accumulate it will encourage flies and rats to breed, which are vectors of disease. It is possible that piles of waste will also contain excreta so the risks will be the same as those listed in (a).
These problems could be reduced by providing a waste management service that ensured wastes were collected and disposed of appropriately.
- c.Handwashing before eating is an important aspect of good hygiene practice. Without this there is a risk of transmitting pathogens into your mouth, which may result in the faecally transmitted diseases listed in (a).
These risks could be reduced by ensuring everyone has access to sufficient water to make it easy to wash hands routinely and by introducing community programmes to inform people about the benefits of handwashing and good hygiene.
Summary of Study Session 2