Firefighters in Maryland who were free of cancer in 1991 and who agreed to participate were enrolled into a study to examine the association of occupational dust exposures with various cancers. As a condition of enrollment, the firefighters gave the researchers permission to link their personal information to state cancer registries, and agreed to complete an initial intake evaluation to collect data on risk factors for cancer (e.g. family history, diet. Researchers followed the firefighters in the cancer registries until death, loss-to follow-up or 1996.

Based on the information provided above:

1. Identify the type of study design.
2. What are strengths of this design?
3. What are some disadvantages of this type of epidemiologic study design (in general)?
4. List potential sources of bias for the study described above.
5. What other epidemiologic design could you use? Why?Strengths and weaknesses?