On talc, tremolite, and tergiversation.
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Biomedical subjects
Publications and source records attributed to R Reger.
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Chest radiographs, taken at a 9-year interval for 1,261 U.S. coal miners, were read for pneumoconiosis side-by-side by six readers in a controlled trial. Incidence and progression of small, rounded opacities were consistent with levels predicted from dose-response curves developed by the British Pneumoconiosis Field Research interpolated at a concentration derived from U.S. compliance levels mandated over the last 9 years. The results imply that the level of pneumoconiosis in U.S. miners is being reduced through application of the current 2 mg/m3 standard. The long developmental period for pneumoconiosis necessitates that further study be undertaken to verify this finding and to determine whether 2 mg/m3 is an appropriate regulatory dust level for the prevention of category 2 or greater simple pneumoconiosis over a 35-year period.
Examination of the incidence and progression of pneumoconiosis over 9 years in 1,261 nationally distributed U.S. coal miners has been undertaken in relationship to potential causative factors. Use has been made of a large body of data on dust levels collected by the Mine Safety and Health Administration principally for compliance purposes. Reported dust levels were low and generally under the current 2 mg/m3 standard. No link between dust level and disease progression could be detected. Some evidence was seen that radiological change was related to dust exposures prior to the study in both coal and noncoal mines, and thus experienced before the current dust standards were mandated. Neither migration of miners nor mining method appeared to be associated with disease incidence or progression. None of these findings can be taken as final, as the period of study is short and the number of cases of pneumoconiosis few. Further study is under way to obtain more reliable information over a longer period of follow-up.
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An area of major concern in considering increased coal production and utilization is the health and safety of increased numbers of workers who mine, process, or utilize coal. Hazards related to mining activities in the past have been especially serious, resulting in many mine related accidental deaths, disabling injuries, and disability and death from chronic lung disease. Underground coal mines are clearly less safe than surface mines. Over one-third of currently employed underground miners experience chronic lung disease. Other stresses include noise and extremes of heat and cold. Newly emphasized technologies of the use of diesel powered mining equipment and the use of longwall mining techniques may be associated with serious health effects. Workers at coal-fired power plants are also potentially at risk of occupational diseases. Occupational safety and health aspects of coal mining are understood well enough today to justify implementing necessary and technically feasible and available control measures to minimize potential problems associated with increased coal production and use in the future. Increased emphasis on safety and health training for inexperienced coal miners expected to enter the work force is clearly needed. The recently enacted Federal Mine Safety and Health Act of 1977 will provide impetus for increased control over hazards in coal mining.
A limited investigation of respiratory and other symptom prevalence, plus before and after shift ventilatory capacity was conducted among a group of 17 meat wrappers exposed to pyrolysis products of polyvinyl chloride and a group of 21 control subjects. Exposed meat wrappers showed a higher prevalence of cough, phlegm, hay fever, and asthma than did the control group. The exposed group also demonstrated relative decreases in forced expiratory volume, one second (FEV1.0) and forced expiratory flow 50% (FEF50) after one shift of work; whereas, the controls showed an opposite tendency. These findings suggest that meat wrappers exposed to pyrolysis products of polyvinyl chloride might be adversely affected. The results, while suggestive, are not totally conclusive owing to the fact that there was not ideal matching of the exposed and control groups in regard to age, height, race, sex, and smoking status.
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Seventeen of an original cohort of 25 non-smoking working coal miners and 6 age-matched controls studied in 1969 were re-examined in 1973. Measurements included lung volumes, maximal expiratory flow-volume curves, and closing volumes. Miners, when compared with controls, showed a marked decline in maximal expiratory flow at mid-vital capacity (V 50%) over the 4-year period which took place without significant change in the 1-second forced expiratory volume (FEV1). Frequency dependence of dynamic compliance (Cdyn) in association with an increased upstream airways resistance (Rus), and also loss of lung elastic recoil (PL(St)) which were present at the time of the original study led to similar declines in V 50%. An abnormally elevated closing capacity expressed as a percentage of total lung capacity (CC/TLC)% was found in 9 miners (53%) and none of the controls. Closing volume as a percentage of vital capacity (CV/VC)% was abnormal in 4 miners (23.5)% and no controls. Measurement of closing volume did not relate well to the variety of mechanical abnormality present on the original study; namely, loss of recoil or small airways obstruction. The presence of an elevated (CC/TLC)% and (CV/VC)% correlated mainly with the presence of hyperinflation as indicated by an elevated residual volume.
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