Explain why it would or would not be ethical to perform an experiment in each of the scenarios below.

(a) A researcher is interested in the effects of smoking cigarettes on human health.
The researcher would like to assign subjects to the two treatments smoked cigarettes for 25 years and did not smoke cigarettes at all in a 25 year period in a prospective study.

(b) A researcher is interested in determining the efficacy of a new HIV/AIDS drug.
The researcher would like to assign subjects to standard treatment and the new drug in a randomized controlled study.

(c) A researcher is interested in identifying the risk factors associated with Alzheimer’s disease. The researcher would like to assign subjects to several different risk factors in a 20-year prospective study.

(d) A researcher is interested in identifying the relationship between hormone therapy and breast cancer. The researcher would like to assign subjects to the treatments hormone therapy, time-reduced hormone therapy, and no hormone therapy at all in a 20-year prospective study.