For each of the descriptions below, identify the studydesign. Choose only one study design perdescription: ecologic, cross-sectional, case-control,retrospective cohort or prospective cohort.
In the year 2000, the records of 8,047white male smelter workers, believed to have been exposed to highquantities of arsenic, were gathered for those who began workbetween 1938 and 1963. Death certificates were examined toascertain the cause of death for this group up until 2000. Theywere compared to death certificates from the workers in otheroccupations of the same race, gender and time period. Higher ratesof mortality from respiratory cancer and heart disease were foundamong those who had worked at least 15 years as smelterworkers.