Answer:
a) The relative risk is 1.8
b) The attributable risk is
c) There is a relationship between exposure and tumor risk
Step-by-step explanation:
The number of exposed rats that develop tumors, a = 42
The number of rats exposed to the carcinogen = 600 rats
The number of exposed rats that did not develop tumors, b = 600 - 42 = 558
The number of not exposed rats in the control group = 350 rats
The number of rats that develop tumors in the control group, c = 13 tumors
The number of not exposed rats that did not develop tumors, d = 350 - 13 = 337 rats
a) The relative risk, RR = a/(a + b)/(c/(c + d))
∴ RR = (42/(42 + 558))/(13/(13 + 337)) = 49/26 = 1.8
b) The attributable risk = (a - c)/a
∴ The attributable risk = (42 - 13)/42 =
c) The odds ratio = (a·b)/(c·d)
∴ The odds ratio = 42 × 558/(13 × 337) = 23439/4381 ≈ 5.35
Given that the result of attributable risk is positive, there is an indication that there is a higher probability to develop tumor when exposed to the potential carcinogen, therefore, there is a relationship between exposure and tumor risk
