Question

January 21, Example 3: Malathion is a pesticide often used by municipalities as a means of mosquito control, and is distributed in geographical areas through aerial spraying. Some claim that malathion is a chemical that is dangerous to human health and should not be for mosquito control. People living in a certain area had their heart-rates examined prior to the area being sprayed with malathion. Two weeks after the spraying campaign was completed, the sample people had their heart-rates examined. The results are given in the table below.

		Before spraying
		Elevated Heart Rate	Normal heart rate
After Spraying	Elevated Heart rate	126	414
	Normal Heart rate	390	999

Find the relative risk.

Answer 1

Relative risk measures the ratio of the risk of developing a condition (or disease) for those exposed to a risk factor, versus the the risk of exhibiting the condition for those that are not exposed to the risk factor         

	Disease	Disease free	total
exposed	126	414	540
non exposed	390	999	1389
total	516	1413	1929

           
          

relative risk =(126/540)/(390/1389) =   0.8310