cellulose-triacetate and Myocardial-Ischemia

To update the mortality experience of employees of a factory that produced cellulose triacetate film base at Brantham in the United Kingdom and generate information on the effects of exposure to methylene chloride, in particular, mortality from cardiovascular disease and cancers of the lung, liver and biliary tract, pancreas and brain.. All 1,785 male employees with a record of employment at the film factory in 1946-1988 were followed through 2006, including 1,473 subjects exposed to methylene chloride on average for 9 years at a concentration of 19 ppm (8 h time-weighted average).. A total of 559 deaths occurred during the follow-up period. In the subcohort of workers exposed to methylene chloride, substantially reduced mortalities compared with national and local rates were found for all causes, all cancers, and all the principal cancer sites of interest except for brain cancer. There was a small excess of brain cancer deaths (8 observed and 4.4 expected), but no evidence of an association with exposure to methylene chloride. Lung cancer mortality was significantly reduced in exposed workers, even compared to the low mortality rate in the local population (SMR 55). In contrast, mortality from ischaemic heart disease in exposed workers was slightly increased compared with local rates (SMR 102), but was lower in active employees (SMR 94; local rates), where a direct effect of exposure to methylene chloride should be concentrated.. The study provided no indication that employment at the plant, or exposure to methylene chloride, had adversely affected the mortalities of workers.

Topics: Adult; Cause of Death; Cellulose; Chemical Industry; Cohort Studies; Humans; Male; Methylene Chloride; Myocardial Ischemia; Neoplasms; Occupational Diseases; Occupational Exposure; Solvents; Survival Rate; United Kingdom; Young Adult

Occupational exposure to methylene chloride, together with carboxyhemoglobin concentrations, has not been studied previously.. Carboxyhemoglobin levels were measured in non-smoking employees exposed to varying concentrations of methylene chloride during the manufacture of cellulose triacetate fibers. The observed carboxyhemoglobin levels were compared to predicted concentrations using a pharmacokinetic model.. The presence of carboxyhemoglobin in non-smokers exposed to methylene chloride results primarily from the metabolism of methylene chloride in the liver and exhibits a linear dose-response relationship. The observed levels of carboxyhemoglobin in non-smokers at the end of an 8-hour shift depend upon exposures to methylene chloride that day but are independent of occupational exposures on previous days. The observed daily concentrations of carboxyhemoglobin are consistent with predicted concentrations using a pharmacokinetic model. While varying exposure patterns were shown to change the rate of metabolite formation at the end of shift, these same exposure patterns had almost no effect on the total amount of carbon monoxide in the blood.. While the present study addresses the relationship between methylene chloride, carbon monoxide, carboxyhemoglobin and ischemic heart disease, it does not address the issue of tumorigenicity, which is also the basis for the current U.S. Occupational Health and Safety workplace exposure limit of 25 ppm. This study provides support for the conclusion that the current American Conference of Governmental Industrial Hygienists 8-hour Threshold Limit Value of 50 ppm adequately protects human health with regard to ischemic heart disease and carboxyhemoglobin formation among non-smokers.

Topics: Carbon Monoxide; Carboxyhemoglobin; Cellulose; Humans; Male; Methylene Chloride; Myocardial Ischemia; Occupational Exposure; Sensitivity and Specificity

Mortality ascertainment was extended through 1990 for a cohort of 1271 workers involved in the production of cellulose triacetate fiber at a plant in Rock Hill, South Carolina. Each subject was employed for at least three months between 1 January 1954 and 1 January 1977 in jobs that entailed exposure to the highest concentrations of methylene chloride. Median exposures in 1977 ranged from 140 to 745 ppm (8-h time-weighted average). The observed numbers of deaths from specific causes were compared with the expected numbers of deaths computed from rates in York County, South Carolina. For most causes of death, there was little if any association with employment. Among causes of particular interest, no new deaths were observed from cancer of the liver and biliary tract, although the excess from the earlier study persisted (4 observed, 1.34 expected). No excess mortality was observed for cancer of the pancreas (2 observed, 2.42 expected) or for ischemic heart disease (43 observed, 47.8 expected).

Topics: Cause of Death; Cellulose; Cohort Studies; Humans; Methylene Chloride; Myocardial Ischemia; Neoplasms; North Carolina; Occupational Diseases; Occupational Exposure; Risk Factors; Survival Analysis