Mortality among workers in the Florida phosphate industry. I. Industry-wide cause-specific mortality patterns.

A retrospective cohort mortality study was conducted on 17,601 white and 4,722 nonwhite male workers in the Florida phosphate mining and chemical processing industry. Concerns about potential risks from naturally-occurring sources of ionizing radiation and anecdotal reports of lung cancer among workers prompted this investigation. Historical follow-up was conducted for the years 1949 to 1978. In comparison with U.S. rates, small excess of mortality rates of lung cancer were observed for white (standardized mortality ratio [SMR] equals 1.22) and nonwhite workers (SMR = 1.24); however, these excesses disappeared when contrasts were made with prevailing rates in Florida. Emphysema mortality was also slightly elevated in comparison with U.S. rates; the SMRs were 1.48 and 1.73 for white and nonwhite workers, respectively. Neither disease was related to overall length of employment. Detailed analyses of mortality in relation to work assignments are presented in the companion article.

Mortality among workers in the Florida phosphate industry. II. Cause-specific mortality relationships with work areas and exposures.

Small excesses of lung cancer and emphysema mortality had been detected among an historical cohort of 17,601 white and 4,722 nonwhite Florida phosphate industry workers. Internal mortality rate comparisons were made between worker subcohorts classified according to length of employment in 16 work areas and according to employment duration in jobs grouped by potential exposures to 10 agents, including alpha radiation. The only consistent associations seen were increased lung cancer mortality rates among long-term workers in plant-wide services and skilled crafts jobs. There was no evidence to support causal associations with exposures characteristic of the phosphate industry.