Case studies in occupational epidemiology. Steenland K, ed. New York: Oxford University Press, 1993 Jan; :35-46
In an effort to determine a link between acid mist exposure and cancer of the larynx, NIOSH investigators reviewed a cohort of 1,156 men which had been studied previously. This study was described as part of a text book and took the reader through the same steps that the investigator took when conducting the actual study to allow the student to solve the same problems that the investigator solved in the course of the study. The cohort was exposed to acid mists during the pickling of steel. A mortality study had been conducted using this cohort in 1987. The men had worked at three midwestern steel facilities from the 1940s through the 1980s. By 1985, 32% of the cohort had died, with an excess of lung cancer. Two deaths due to larynx cancer were noted, whereas one had been expected. The most complete and oldest data on age specific laryngeal cancer incidence existed for the state of Connecticut with rates from 1935 through 1979. These, plus rates for New York City from 1950 to 1972, were included to calculate a range of results. The percentage of completed interviews obtained from those members of the cohort still living was 79% compared to 59% where the next of kin supplied the information. Nine larynx cancers were observed in the cohort, five of whom had died. Only two of those deceased had any indication of larynx cancer on the death certificate. The nine cases averaged 26 years since first exposure, and averaged age 53 at diagnosis. All were smokers or former smokers. Nine men also reported benign growths on the vocal cords, one of which subsequently developed into larynx cancer.