Alice Greife

Cancer mortality in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

BACKGROUND In both animal and epidemiologic studies, exposure to dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD) has been associated with an increased risk of cancer. METHODS We conducted a retrospective cohort study of mortality among the 5172 workers at 12 plants in the United States that produced chemicals contaminated with TCDD. Occupational exposure was documented by reviewing job descriptions and by measuring TCDD in serum from a sample of 253 workers. Causes of death were taken from death certificates. RESULTS Mortality from several cancers previously associated with TCDD (stomach, liver, and nasal cancers, Hodgkins disease, and non-Hodgkins lymphoma) was not significantly elevated in this cohort. Mortality from soft-tissue sarcoma was increased, but not significantly (4 deaths; standardized mortality ratio [SMR], 338; 95 percent confidence interval, 92 to 865). In the subcohort of 1520 workers with greater than or equal to 1 year of exposure and greater than or equal to 20 years of latency, however, mortality was significantly increased for soft-tissue sarcoma (3 deaths; SMR, 922; 95 percent confidence interval, 190 to 2695) and for cancers of the respiratory system (SMR, 142; 95 percent confidence interval, 103 to 192). Mortality from all cancers combined was slightly but significantly elevated in the overall cohort (SMR, 115; 95 percent confidence interval, 102 to 130) and was higher in the subcohort with greater than or equal to 1 year of exposure and greater than or equal to 20 years of latency (SMR, 146; 95 percent confidence interval, 121 to 176). CONCLUSIONS This study of mortality among workers with occupational exposure to TCDD does not confirm the high relative risks reported for many cancers in previous studies. Conclusions about an increase in the risk of soft-tissue sarcoma are limited by small numbers and misclassification on death certificates. Excess mortality from all cancers combined, cancers of the respiratory tract, and soft-tissue sarcoma may result from exposure to TCDD, although we cannot exclude the possible contribution of factors such as smoking and occupational exposure to other chemicals.

Mortality among workers exposed to ethylene oxide.

BACKGROUND Ethylene oxide is a sterilant gas that causes leukemia and other cancers in animals. Studies in Sweden have shown an excess of leukemia and stomach cancer in humans exposed to ethylene oxide, but other studies have generally failed to confirm these findings. METHODS We conducted a study of mortality in 18,254 U.S. workers exposed to ethylene oxide at 14 plants producing sterilized medical supplies and spices. The subjects averaged 4.9 years of exposure to the gas and 16 years of follow-up. The exposure levels in recent years averaged 4.3 ppm (eight-hour time-weighted adjusted exposure) for sterilizer operators and 2.0 ppm for other workers. The levels in earlier years are likely to have been several times higher. Mortality in this cohort was compared with that in the general U.S. population. RESULTS Overall there was no significant increase in mortality from any cause in the study cohort. The standardized mortality ratios (SMRs) were 0.97 for leukemia (95 percent confidence interval, 0.52 to 1.67; 13 deaths observed), 1.06 for all hematopoietic cancers (95 percent confidence interval, 0.75 to 1.47; 36 deaths), and 0.94 for stomach cancer (95 percent confidence interval, 0.45 to 1.70; 11 deaths). Analyses according to job category and according to the duration of exposure showed no excess in cancers, as compared with the rate in the general population, but there was a significant trend toward increased mortality with increasing lengths of time since the first exposure for all hematopoietic cancers. The rate of death from hematopoietic cancer (especially non-Hodgkins lymphoma) was significantly increased among men (SMR, 1.55; 27 deaths). Mortality from leukemia in recent years (1985 through 1987) was significantly increased among men (SMR, 3.45; 5 deaths). CONCLUSIONS For the entire cohort, there was no increase in mortality from hematopoietic cancer. There was a slight but significant increase among men, however. Among men and women combined, there was a trend toward an increased risk of death from hematopoietic cancer with increasing lengths of time since the first exposure to ethylene oxide.

National Institute for Occupational Safety and Health General Industry Occupational Exposure Databases: Their Structure, Capabilities, and Limitations

Abstract The passage of the Occupational Safety and Health Act of 1970 resulted in increased concern for the safety and health of workers in the United States. Early in 1971, a Hazard and Disease Task Force, formed by the Department of Health, Education, and Welfare, identified a need for more detailed information on the distribution of potential exposures of employees in industries regulated in the Occupational Safety and Health Act to chemical and physical hazards. To address this need, the National Institute for Occupational Safety and Health conducted two major national surveys as part of its hazard surveillance program. The first, conducted in 1972–1974, was called the National Occupational Hazard Survey. The second, conducted in 1981–1983, was called the National Occupational Exposure Survey. Each survey employed a stratified probability sample, and collected observational data on potential direct workplace exposures and also exposure to tradenamed products. Completed nearly a decade apart, the data...

Comparison of serum levels of 2,3,7,8-TCDD in TCP production workers and in an unexposed comparison group

Abstract Serum 2,3,7,8-TCDD levels were measured as an estimate of exposure to this isomer in 143 workers who were employed at either of two plants in New Jersey and Missouri which manufactured chemicals contaminated with 2,3,7,8-TCDD and in 54 unexposed referents. The mean serum 2,3,7,8-TCDD levels for all workers was 251.7 parts per trillion (ppt) and, for all referents combined, the mean serum level was 7.8 ppt. The mean level of 2,3,7,8-TCDD present in the serum of workers at the date of termination of exposure (half-life extrapolated) was 2600 ppt and 870 ppt for the New Jersey and Missouri workers, respectively. Overall, the levels in the workers significantly correlated with duration of exposure in 2,3,7,8-TCDD-contaminated processes (r = 0.83, p

Role of exposure databases in epidemiology

At present, exposure databases record data primarily for regulatory purposes; they have not focused on serving the needs of epidemiologists or public health. However, the modification of exposure databases could facilitate their use in epidemiology. Characteristics necessary to enhance the use of all databases include easy access by users; documentation of methods, sampling bias, error, and inconsistences; widespread coverage in time and space; and methods and measures for estimating exposure of individuals as well as populations. Also needed are exposure scenarios and models to estimate exposures for geographic areas and time intervals not currently sampled. Multidisciplinary teams are needed to examine current databases, to review strategies for improving data collection, and to suggest and help implement appropriate changes. A long-term goal is to develop and validate data from exposure scenarios and models using data on the relationship of exposure to doses measured in humans.