1. to 3. Several different models can potentially explain the elevated cancer rates sometimes observed in people living near electric power lines. Four such models are given below.
The questions that follow contain data that one might gather to test the above models. For each question, mark the model(s) that the given data refutes. Base your answer only on the data indicated.
Models
(A) Transformers on electric power lines occasionally leak carcinogenic chemicals. These chemicals cause people who live near power lines to acquire cancer more frequently than the general population.
(B) People who live near power lines have relatively lower per-capita incomes than the general population. People with low incomes tend to have nutritionally poor diets. Poor diets cause a higher than average incidence of cancer.
(C) People who live near power lines have relatively higher per-capita incomes than nearby residents. People with higher incomes tend to have a higher daily alcohol intake, and this causes them to have a higher incidence of cancer.
(D) The electromagnetic radiation produced by electric power lines causes cancer. However, the effect of this radiation is not very strong---out of 100,000 residents living near power lines, we would expect, on average, only 5 excess cancer deaths in one year.
1. Data: A correlation showing that the per-capita income is highest for people living nearest power lines, and decreases with increasing distance from power lines.
Refutes:
2. Data: A negative correlation between daily alcohol intake and the nutritional quality of the diet.
Refutes:
3. Data: An experiment was done in which 100 white mice were randomly divided into two groups. One group was exposed to the chemicals in transformers, while a control group was not. The mice exposed to the chemicals in the transformers had a significantly elevated cancer incidence.
Refutes:
4. Scientists currently believe that which of the following models are correct? (We acknowledge that a model which is supported now may be rejected in the future.)
Chapter 15. Do Electromagnetic Fields Cause Cancer?