Mortality among a cohort of uranium mill workers: an update.

AIMS: To evaluate the mortality experience of 1484 men employed in seven uranium mills in the Colorado Plateau for at least one year on or after 1 January 1940. METHODS: Vital status was updated through 1998, and life table analyses were conducted. RESULTS: Mortality from all causes and all cancers was less than expected based on US mortality rates. A statistically significant increase in non-malignant respiratory disease mortality and non-significant increases in mortality from lymphatic and haematopoietic malignancies other than leukaemia, lung cancer, and chronic renal disease were observed. The excess in lymphatic and haematopoietic cancer mortality was due to an increase in mortality from lymphosarcoma and reticulosarcoma and Hodgkin's disease. Within the category of non-malignant respiratory disease, mortality from emphysema and pneumoconioses and other respiratory disease was increased. Mortality from lung cancer and emphysema was higher among workers hired prior to 1955 when exposures to uranium, silica, and vanadium were presumably higher. Mortality from these causes of death did not increase with employment duration. CONCLUSIONS: Although the observed excesses were consistent with our a priori hypotheses, positive trends with employment duration were not observed. Limitations included the small cohort size and limited power to detect a moderately increased risk for some outcomes of interest, the inability to estimate individual exposures, and the lack of smoking data. Because of these limitations, firm conclusions about the relation of the observed excesses in mortality and mill exposures are not possible.

Mortality of workers employed in shoe manufacturing.

A retrospective cohort mortality study was conducted among 7814 white shoe manufacturing workers followed from 1940 through 1982. The workers were potentially exposed to solvents (including toluene) and solvent-based adhesives. Benzene may have been present as an impurity of toluene. Mortality due to leukemia and aleukemia was not statistically significantly elevated. Statistically significant excess mortality due to cancer of the trachea, bronchus and lung was observed in the total cohort [standardized mortality ratio (SMR) 147, 95% confidence interval (95% CI) 120-180] and showed a statistically significant trend in standardized relative risk with increasing potential latency, but not with increasing duration of employment. Chronic nonmalignant respiratory disease was significantly elevated among the men (SMR 158, 95% CI 114-217) but was less than expected among the women (SMR 79), a finding suggesting a possible contribution of smoking to the mortality from respiratory cancer. However, adjustment for the potential effects of smoking did not completely eliminate the increased risk for lung cancer.

Cardiovascular mortality among munitions workers exposed to nitroglycerin and dinitrotoluene.

A retrospective cohort mortality study with 5529 nitroglycerin, 4989 dinitrotoluene, and 5136 unexposed workers compared the mortality of the exposed groups with that of the United States population and that of the unexposed group with life-table analysis and Poisson regression. Mortality from ischemic heart disease was close to that expected, and mortality from cerebrovascular disease was slightly less than that expected, for the workers with both nitroglycerin and dinitrotoluene exposure and for those with dinitrotoluene exposure only. A significant interaction between age and nitroglycerin exposure was detected in the Poisson regression analyses for ischemic heart disease, particularly for workers actively exposed to nitroglycerin. The rate ratio for the workers under 45 years of age and actively exposed to nitroglycerin was 3.30 (95% confidence interval 129-8.48). This study did not show a chronic effect of nitroglycerin or dinitrotoluene exposure on cardiovascular disease risk. Potential biases related to the company's medical screening program may have limited the ability to detect chronic cardiovascular effects.

Mortality of industrial workers exposed to acrylonitrile.

OBJECTIVES: This study was designed to evaluate the relationship between occupational exposure to acrylonitrile and cancer mortality. MATERIALS AND METHODS: Workers (18079 white men, 4293 white women, 2191 nonwhite men, and 897 nonwhite women) employed in acrylonitrile production or use in the 1950s through 1983 were followed through 1989 for vital status and cause of death. Exposure-response relationships were evaluated from quantitative estimates of historical exposures. Tobacco use was determined for a sample of workers to assess potential confounding. Mortality rates between the exposed and unexposed workers in the cohort were compared using the Poisson regression. RESULTS: Analyses by cumulative, average, peak, intensity, duration, and lagged exposure revealed no elevated risk of cancers of the stomach, brain, breast, prostate or lymphatic and hematopoietic systems. Mortality from lung cancer was elevated for the highest quintile of cumulative exposure. When the decile categories were used, the relative risk did not continue to increase at higher levels. Adjustment for cigarette use reduced the risk for lung cancer only slightly. Separate analyses for wage and salaried workers, long-term and short-term workers, fiber and nonfiber plants, and individual plants revealed no clear exposure-response patterns. CONCLUSIONS: The results indicate that exposure to acrylonitrile at the levels studied is not associated with an increased relative risk for most cancers of a priori interest. The excess of lung cancer in the highest quintile of cumulative exposure may indicate carcinogenic activity at the highest levels of exposure, but analyses of exposure-response do not provide strong or consistent evidence for a causal association.

The NIOSH/FAA Working Women's Health Study: evaluation of the cosmic-radiation exposures of flight attendants. Federal Aviation Administration.

Air crew are exposed to elevated levels of cosmic ionizing radiation of galactic and solar origin and are among the more highly exposed occupational groups to ionizing radiation in the United States. Depending on flight route patterns, the annual dose may range from 0.2 to 5 mSv. By comparison, the average annual radiation dose equivalent of occupationally exposed adults in the United States is estimated to be 1.1 mSv. Cosmic-radiation dose depends primarily on altitude and geomagnetic latitude and to a lesser degree on solar activity. Although the International Commission on Radiological Protection has recommended that air crew exposures to natural radiation in-flight be treated as occupational exposures, United States flight crew exposures to natural cosmic radiation are not regulated or typically monitored. There are approximately 148,000 air crew (flight deck crew and flight attendants) in the United States.

Evaluation of exposures to fluorocarbon 113 in a horizontal and a vertical laminar airflow clean room.

Exposures to 1,1,2-trichloro-1,2,2-trifluoroethane or fluorocarbon (FC) 113 were evaluated in a horizontal laminar airflow (HLAF) clean room and a vertical laminar airflow (VLAF) clean room. A full period consecutive samples measurement strategy was employed. Data were used to calculate 8-hour time-weighted averages (8-TWA) for major work groups and to characterize exposures associated with specific cleaning tasks. The MIRAN 1B infrared analyzer was used to estimate peak concentrations. In the HLAF clean room, 8-TWAs ranged from 193 to 439 ppm; in the VLAF clean room, 8-TWAs ranged from 110 to 935 ppm. These levels were below the current Occupational Safety and Health Administration permissible exposure limit and the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit for FC 113 of 1000 ppm. Short-term sample concentrations ranged from 104 ppm (inspection) to 1080 ppm (assembly) in the HLAF clean room and 51 ppm (packaging)-3380 ppm (flushing) in the VLAF clean room. In the VLAF clean room, several short-term concentrations measured during the flushing task--1421 ppm and 2522 ppm--were above the NIOSH short-term exposure limit (STEL) of 1250 ppm. These data suggest the possibility that the STEL may be exceeded for tasks involving direct work with liquid FC 113. Peak exposure levels may be reduced by modification of worker position in the HLAF clean room and by use of open wire tables in the VLAF clean room.

Workshop on harmonization of serving future needs with occupational exposure databases--inhalation modeling, session IIIA.

This workshop was one of several that took place at the International Symposium on Occupational Exposure Databases and Their Application for the Next Millennium held in London from November 1-3, 1999. About 30 delegates participated in the workshop. The agenda for the discussions was provided by a white paper prepared by the organizers. The workshop produced a conceptual outline for a general-purpose prediction model for inhalation exposure, and constructed a list of important input variables for successful model development. Evaluation of prototype models was discussed in some detail, and the workshop concluded with suggestions for taking forward the ideas discussed and maintaining the momentum and interest generated during the symposium.

Fluorocarbon 113 exposure and cardiac dysrhythmias among aerospace workers.

We investigated the cardiotoxic effects of 1,1,2-Trichloro-1,2,2- Trifluoroethane (fluorocarbon 113 or FC113) exposures among healthy workers cleaning rocket and ground support equipment for the National Aeronautic and Space Administration (NASA) programs. Exposure and ambulatory electrocardiographic (ECG) monitoring data were evaluated on 16 workers, each of whom was examined on exposed and nonexposed workdays. We examined whether there was a greater rate of dysrhythmias on an exposed workday relative to a nonexposed workday. Overall, we found no within subject differences in the rate of ventricular and supraventricular premature beats (number per 1,000 heart beats), fluctuations in the length of the P-R interval, or heart rate. We found that levels of FC113 exposures below the Occupational Safety and Health Administration (OSHA) 8-hour time-weighted-average (TWA) standard of 1,000 ppm did not induce cardiac dysrhythmias or subtle changes in cardiac activity. However, because fluorocarbons may sensitize the heart to epinephrine, this study's negative findings based on sedentary and fairly healthy workers may not be generalizable to other populations of workers who are not as healthy or engaged in more physically demanding work.