Before the transition from steam- to diesel-powered locomotives during the 1950s certain railroad workers had the opportunity for significant occupational exposure to asbestos. Past studies have ...demonstrated that older workers with jobs associated with the repair of steam locomotives had the most exposure. To determine the prevalence of currently employed railroad workers with past asbestos exposure we surveyed 514 white male employees of an active US railroad by mail questionnaire. Twenty-one percent (50/242) of the workers 50 years old or greater had likely asbestos exposure compared to 3% (9/275) of the workers 49 years old or less (p less than .001). Fifteen (30%) of the 50 older workers with likely asbestos exposure had current job titles no longer suggestive of past exposure. The duration of exposure of these older active workers was short, (median = 3 years; range, 6 months to 15 years). A history of past asbestos exposure may still be obtained among active railroad workers with past railroad shop employment.
The American Thoracic Society (ATS) has formulated guidelines for spirometry. We hypothesized that individuals with SCI (SCI), as a result of weak respiratory muscles, would exhibit poor test ...acceptability and reproducibility. Seventy-eight SCI subjects (39 with complete SCI) answered a respiratory questionnaire and performed spirometry. Of those with complete SCI, the proportion of subjects which met ATS criteria decreased with higher levels of injury. Poor test performance was not associated with age, respiratory symptoms or muscle fatigue. The most common reason for failing to meet ATS criteria for acceptability was excessive back extrapolated volumes (EBEV). Individuals with efforts that were acceptable except for EBEV and/or for exhalation of less than six seconds had values for forced expiratory volume in one second (FEV
1
) and forced vital capacity (FVC) that were reproducible. If ATS criteria for acceptable spirometry were used in studying subjects with SCI, individuals producing otherwise reproducible values for FVC and FEV
1
would be excluded. We found reproducibility similar to what has been reported in other cohorts and conclude that longitudinal study of respiratory function in SCI is feasible. (J Am Paraplegia Soc; 16: 197-203)
The risk of lung cancer as a result of exposure to diesel exhaust from railroad locomotives was assessed in a cohort of 55,407 white male railroad workers 40 to 64 yr of age in 1959 who had started ...railroad service 10 to 20 years earlier. The cohort was traced until the end of 1980, and death certificates were obtained for 88% of 19,396 deaths; 1,694 lung cancer cases were identified. Yearly railroad job from 1959 to death or retirement was available from the Railroad Retirement Board, and served as an index of diesel exhaust exposure. Directly standardized rates and a proportional hazards model were used to calculate the relative risk of lung cancer based on work in a job with diesel exhaust exposure beginning in 1959. A relative risk of 1.45 (95% CI = 1.11, 1.89) for lung cancer was obtained in the group of workers 40 to 44 yr of age in 1959, the group with the longest possible duration of diesel exposure. The cohort was selected to minimize the effect of past railroad asbestos exposure, and analysis with workers with possible asbestos exposure excluded resulted in a similarly elevated risk. Workers with 20 yr or more elapsed since 1959, the effective start of diesel exposure for the cohort, had the highest relative risk. These results taken in conjunction with other reported results support the hypothesis that occupational exposure to diesel exhaust results in a small but significantly elevated risk for lung cancer.
The effect of exposure to ozone (O3) in ambient air on respiratory function was studied in 30 healthy adult nonsmokers engaged in a regular daily program of outdoor exercise in Tuxedo, NY during the ...summer of 1985. Each subject did the same exercise each day, but exercise intensity and duration varied widely between subjects, with minute ventilation ranging from 20 to 153 L and duration ranging from 15 to 55 min. Spirometry was performed immediately before and after each exercise period. O3 concentrations during exercise ranged from 21 to 124 parts per billion (ppb). All measured functional indexes showed significant (p less than 0.01) O3-associated mean decrements with FVC at -2.1 ml/ppb, FEV1 at -1.4 ml/ppb, PEFR at -9.2 ml/s/ppb, FEF25-75 at -6.0 ml/s/ppb, and FEV1/FVC at -0.038%/ppb. Mean decrements were smaller for 10 subjects with minute ventilations greater than 100 L than for 10 other subjects with minute ventilations between 60 and 100 L or for the 10 subjects with minute ventilations below 60 L. Overall, the functional decrements were similar in magnitude to those we have seen in children engaged in supervised recreational programs in summer camps. For 10 subjects with minute ventilations comparable to those used in controlled 1- and 2-h exposures to O3 in purified air in chambers (50 to 80 L), the effects were about twice as large as those reported for the chamber studies.
This study examined the relationship between lifetime alcohol consumption and respiratory symptoms in 195 subjects (including 111 alcoholics) and FEV1 level in 165 subjects (including 91 alcoholics). ...After adjustment for age and cigarette smoking status, using multiple logistic regression, lifetime alcohol consumption was a significant predictor of chronic cough and chronic phlegm, but not of any wheeze or persistent wheeze. Multiple linear regression analysis indicated that lifetime alcohol consumption was also a predictor of lower levels of FEV1 in a model that included age, pack-years of cigarette smoking, and an interaction between alcohol consumption and pack-years. The interaction between smoking and alcohol consumption was in a direction opposite to the independent effects of alcohol and smoking, suggesting a protective effect of alcohol with heavier amounts of smoking. Additional study is needed to further assess the relationship between respiratory symptoms and alcohol consumption, and between pulmonary function and alcohol consumption.
How variable is the deposition of inhaled methacholine (MCH) in the respiratory tract during a challenge test? Does this variability contribute to the variability of airway responsiveness? To examine ...these questions we estimated the deposition of polydisperse MCH droplets by measuring the deposition of surrogate diethylhexyl sebacate (DEHS) droplets that were similar in size (1.5 microns) but monodisperse. Light scattering photometry and flow measurements were used to compute inspired and expired DEHS particle number. Deposition of DEHS during 4 breaths was measured twice at baseline and after every dose of MCH during an abbreviated challenge test in 16 subjects. Deposition was then compared with reactivity. Reactivity to MCH was expressed as the dose-response slope; it was calculated as percent final change in FEV1/cumulative dose MCH inhaled. Dose-response slopes ranged from zero (nonreactive) to -15.0 (very reactive) %/mumol (mean -3.2 +/- 5.3 SD). Seven subjects had a 20% or greater decrement in FEV1 after their highest MCH dose. Baseline DEHS deposition, which ranged from 66 to 84% (mean 77 +/- 5 SD), was not significantly different between responders and nonresponders and was not a significant predictor of the dose-response slope. Reactivity was significantly associated with an increase in deposition produced by MCH (p less than 0.007). This increase was small, however (relative change less than 7%), so that the effect on the deposited dose of MCH was minimal. We conclude that, with the breathing pattern used, individual differences in DEHS (and MCH) deposition were small and contributed little to intersubject variability of responsiveness to inhaled MCH.
High volume fixed location samples of particles and vapor phase components were collected on filters and XAD-2 resin, respectively, to study the concentration and mutagenicity of diesel exhaust in ...locomotive repair shops at four railroads. The geometric mean concentrations were 96 μg/m
3
geometric standard deviation (GSD) = 2.14 for 23 samples of respirable particles, 164 μg/m
3
(GSD = 1.86) for 26 samples of total particles, and 432 μg/m
3
for 9 samples of vapor phase components. Approximately 30 to 40 percent of the particle mass was extractable in dichloromethane. Chemical class separation of these extracts by normal phase liquid chromatography yielded nearly half the mass in the aliphatic fraction, less than one third in the aromatic fraction, and about one quarter in the polar fraction. Extracts of particle samples were found to be mutagenic in the Salmonella typhimurium forward mutation assay system. Most of this activity was in the polar fraction. None of the vapor phase samples tested contained significant mutagenic activity either with or without metabolic activation. The locomotive repair shop air was approximately 1 order of magnitude more mutagenic than urban air. These elevated levels of mutagens found in diesel locomotive repair shops are consistent with the increased mortality from lung cancer that has been found among railroad workers. Hammond, S.K.; Smith, T.J.; Woskie, S.R.; Braun, A.G.; Lafleur, A.; Liber, H.; Garshick, E.; Schenker, M.B.; Speizer, F.E.: Railroad Diesel Exhaust: Concentration and Mutagenicity. Appl. Occup. Environ. Hyg. 8(11):955-963; 1993.
