Five cross-sectional studies of grain elevator workers.

Five cross-sectional studies were conducted on grain workers in all the terminal elevators in British Columbia, Canada, at 3-year intervals from 1976 to 1988. Civic workers were studied in the same manner as a referent group. The studies consisted of questionnaires, spirometry using the same spirometers, allergy skin tests, and measurement of dust concentration by personal sampling. Although the dust concentration in the elevators was reduced progressively over the years, grain workers had more respiratory symptoms and lower lung function compared with the civic workers in each of the five cross-sectional studies. Exposure to grain dust was associated with significant reduction in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) but not in maximal midexpiratory flow rate or FEV1/FVC, suggesting reduction in volume which may be due to lesions in the lung parenchyma or in the small airways. Cigarette smoking was associated with significant reduction in FEV1, maximal midexpiratory flow rate, and FEV1/FVC due to airflow obstruction, but had no influence on FVC. Workers who took part in all five surveys tended to be a "healthier" selected group, but the grain workers still had lower lung function compared with the civic workers. This study confirmed previous findings that grain dust has adverse effects on the lungs. Cross-sectional study of the grain elevator workers proved to be a consistent and useful method to evaluate occupational health hazards.     

Comparison of dust related respiratory effects in Dutch and Canadian grain handling industries: a pooled analysis.

OBJECTIVES: Four previously conducted epidemiological studies in more than 1200 grain workers were used to compare exposure-response relations between exposure to grain dust and respiratory health. METHODS: The studies included Dutch workers from an animal feed mill and a transfer grain elevator and Canadian workers from a terminal grain elevator and the docks. Relations between forced expiratory volume in one second (FEV1) and exposure were analysed with multiple regression analysis corrected for smoking, age, and height. Exposure variables examined included cumulative and current dust exposure and the numbers of years a subject was employed in the industry. Sampling efficiencies of the Dutch and Canadian measurement techniques were compared in a pilot study. Results of this study were used to correct slopes of exposure-response relations for differences in dust fractions sampled by Dutch and Canadian personal dust samplers. RESULTS: Negative exposure-response relations were shown for regressions of FEV1 on cumulative and current exposure and years employed. Slopes of the exposure-response relations differed by a factor of three to five between industries, apart from results for cumulative exposure. Here the variation in slopes differed by a factor of 100, from -1 to -0.009 ml/mg.y/m3. The variation in slopes between industries reduced to between twofold to fivefold when the Dutch transfer elevator workers were not considered. There was evidence that the small exposure-response slope found for this group is caused by misclassification of exposure and a strong healthy worker effect. Alternative, but less likely explanations for the variation in slopes were differences in exposure concentrations, composition of grain dust, exposure characteristics, and measurement techniques. CONCLUSION: In conclusion, this study showed moderately similar negative exposure-response relations for four different populations from different countries, despite differences in methods of exposure assessment and exposure estimation.     

Byssinosis in Guangzhou, China.

OBJECTIVES--To study the prevalence of byssinosis and other respiratory abnormalities in workers exposed to cotton dust in Guangzhou in two factories that processed purely cotton. METHODS--All the 1320 workers exposed were included. The controls were 1306 workers with no history of occupational dust exposure. Total dust and inhalable dust were measured by Chinese total dust sampler and American vertical elutriator respectively. A World Health Organisation questionnaire was used. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured by a Vitalograph spirometer. RESULTS--The median inhalable dust concentrations ranged from 0.41 to 1.51 mg/m3 and median total dust concentrations from 3.04 to 12.32 mg/m3. The prevalence of respiratory abnormalities in the cotton workers were (a) typical Monday symptoms 9.0%; (b) FEV1 fall by > or = 5% after a shift 16.8%; (c) FEV1 fall by > or = 10% after a shift 4.2%; (d) FEV1 < 80% predicted 6.1%; (e) FEV1/FVC < 75% 4.0%; (f) cough or phlegm 18.2%; (g) chronic bronchitis 10.9%; and (h) byssinosis, defined by (a) plus (b) 1.7%. With the exception of (d), most of the prevalences increased with increasing age, duration of exposure, and cumulative inhalable dust exposure. No increasing trends of respiratory abnormalities were found for current total dust, inhalable dust, and cumulative total dust concentrations. Compared with controls, after adjustment for sex and smoking, with the exception of (d), all the pooled relative risks of respiratory abnormalities were raised for cotton exposure. CONCLUSION--It is concluded that cumulative inhalable cotton is likely to be the cause of byssinotic symptoms, acute lung function decrements, cough, or phlegm, and chronic bronchitis.     

An epidemiologic study of the respiratory effects of trona dust

Trona (sodium sesquicarbonate) is mined from an underground deposit in Wyoming and processed for use in glass, paper, detergent, and chemical applications. Trona dust is alkaline (pH 10.5) and can have an irritant effect on respiratory airways, mucous membranes, and the skin. A study population of 142 underground miners and 88 surface workers from one facility volunteered for an epidemiologic study. Their mean age was 37.6 yr and mean duration of employment was 10.0 yr. The percentage with chronic cough and phlegm was 23%; both symptoms were more common among smokers than nonsmokers. Thirty-three percent of the workers complained of dyspnea when hurrying on level ground or walking up a slight hill. Half of the workers complained of upper respiratory tract symptoms and eye irritation. Both smokers and exsmokers had significant declines of forced expiratory volume in 1 sec (FEV1.0) with age; exsmokers also had declines with work-years when compared to a nonsmoking comparison population. Nonsmokers with personal dust measurements had a significant decline of FEV1.0 related to respirable dust exposure. A shift study of 104 workers revealed a significant fall in FEV1.0 among nonsmokers and surface workers. Significance was approached in the high dust exposure group. An increase in the mean percent predicted forced vital capacity and FEV1.0 was shown for the 125 workers who had a 5-yr follow-up of pulmonary function. There was no correlation between the shift study decrements and the longitudinal 5-yr follow-up. Industrial hygiene dust sampling found elevated levels of total dust but lower respirable dust, with no detectable free silica.     

Respiratory illnesses and ventilatory function among workers at a cement factory in a rapidly developing country

Chronic exposure to Portland cement dust has been reported to lead to a greater prevalence of chronic respiratory symptoms and a reduction of ventilatory capacity. The seriousness of pulmonary function impairment and respiratory disease has not been consistently associated with the degree of exposure. Regular use of appropriate personal protective equipment, if available at the worksite, could protect cement workers from adverse respiratory health effects. For a variety of reasons, industrial workers in rapidly developing countries do not adequately protect themselves through personal protective equipment. This study explores the prevalence of chronic respiratory symptoms and ventilatory function among cement workers and the practice of use of personal protective equipment at work. An interviewer-administered questionnaire was used to collect information on sociodemographic characteristics, smoking profile and history of respiratory health among workers at a Portland cement plant (exposed) and workers occupationally unexposed to dust, fumes and gases (unexposed). Pulmonary function was assessed and pulmonary function impairment was calculated for the exposed and the unexposed workers. A higher percentage of the exposed workers reported recurrent and prolonged cough (30%), phlegm (25%), wheeze (8%), dyspnoea (21%), bronchitis (13%), sinusitis (27%), shortness of breath (8%) and bronchial asthma (6%). Among the unexposed, prevalences of these symptoms were 10, 5, 3, 5, 4, 11, 4 and 3%, respectively. Ventilatory function (VC, FVC, FEV(1), FEV(1)/VC, FEV(1)/FVC and PEF) was significantly lower in the exposed workers compared with unexposed workers. These differences could not be explained by age, body mass index (BMI) or pack-years smoked. Ventilatory function impairment, as measured by FEV(1)/FVC, showed that 36% of the exposed workers had some ventilatory function impairment compared with 10% of those unexposed. Certain jobs with greater exposure to cement dust had lower ventilatory function compared with others among the exposed workers. It was concluded that adverse respiratory health effects (increased frequency of respiratory symptoms and decreased ventilatory function) observed among cement workers could not be explained by age, BMI and smoking, and were probably caused by exposure to cement dust.     

Follow-up study of respiratory health of newly-hired female cotton textile workers

BACKGROUND: Numerous studies have investigated adverse effects of exposure to cotton dust on respiratory health, but very limited longitudinal data are available with regard to the early pulmonary response to cotton dust. Moreover, the adverse effects of occupational exposure to cotton dust have been difficult to separate from the confounding effects of smoking. This setting provided a unique opportunity to evaluate early respiratory effects in newly hired and non-smoking female textile workers. METHODS: To identify early pulmonary responses to cotton dust exposure and associated gram-negative bacterial endotoxin, respiratory symptoms and pulmonary function in 225 newly-hired textile workers were assessed at work initiation, and at three and twelve months later. RESULTS: All the workers were females and nonsmokers, with an average age of 18 years. Symptom incidence at three months was 3.6% for usual cough with phlegm, and 6.7% for usual dry cough. Lung function changes were detectable at one year: FEV1 declined by 70 ml and FVC by 124 ml over the year, and workers reporting respiratory symptoms at three months showed a significantly greater cross-shift drop in FEV1 (- 2.3%) than those without the symptoms (- 0.7%). CONCLUSIONS: These results suggest that the occurrence of respiratory symptoms represents the earliest response to cotton dust exposure, followed by lung function changes. Early respiratory symptoms may be a risk factor for subsequent loss of pulmonary function in cotton textile workers.     

Respiratory function in animal food processing workers

A group of 71 men employed in animal food processing was studied to assess the prevalence of acute and chronic respiratory symptoms and the presence of lung function abnormalities. In addition, a control group of 55 unexposed men was studied for the prevalence of chronic respiratory symptoms. A significantly higher prevalence for most of the chronic respiratory symptoms was found among the exposed workers compared to the control workers. Those workers who smoked had a significantly higher prevalence of chronic cough, chronic phlegm, chronic bronchitis, and chest tightness than the smokers in the control group. For nonsmokers, the differences between exposed and control workers were significant for chronic phlegm and chest tightness. The frequency of acute symptoms associated with the work shift was high among the animal food workers. There were significantly lower measured values for FVC, FEV1, and FEF50 in the exposed group (smokers and nonsmokers) compared to predicted lung function values. In smokers, all measured parameters of ventilatory capacity were significantly less than predicted; for nonsmokers, the FVC and FEV1 were less than normal. Our data indicate that exposure to dust in the animal food industry may be associated with the development of acute and chronic respiratory symptoms and the impairment of lung function. Smoking, in this setting, appears to aggravate these changes.     

Work-related symptoms and dose-response relationships for personal exposures and pulmonary function among woodworkers

BACKGROUND: Four sawmills, a wood chipping mill, and five joineries in New South Wales, Australia, were studied for the effects of personal exposure to wood dust, endotoxins. (1-->3)-beta-D-glucans, Gram-negative bacteria, and fungi on lung function among woodworkers. METHODS: Personal inhalable and respirable dust sampling was carried out. The lung function tests of workers were conducted before and after a workshift. RESULTS: The mean percentage cross-shift decrease in lung function was markedly high for woodworkers compared with the controls. Dose-response relationships among personal exposures and percentage cross-shift decrease in lung function and percentage predicted lung function were more pronounced among joinery workers compared with sawmill and chip mill workers. Woodworkers had markedly high prevalence of regular cough, phlegm, and chronic bronchitis compared with controls. Significant associations were found between percentage cross-shift decrease in FVC and regular phlegm and blocked nose among sawmill and chip mill workers. Both joinery workers and sawmill and chip mill workers showed significant relationships between percentage predicted lung function (FVC, FEV1, FEV1/FVC, FEF25-75%) and respiratory symptoms. CONCLUSIONS: Wood dust and biohazards associated with wood dust are potential health hazards and should be controlled.     

Respiratory symptoms and lung function in jute processing workers: a primary investigation

This paper presents the results of an investigation of respiratory symptoms and lung function of 404 workers who had been exposed to jute dust in a jute mill. Measurement of total dust concentration and analysis of dust composition were also conducted. Most workers in the jute mill were exposed to jute dusts containing less than 5% silica, whereas a few workers were exposed to dusts containing approximately 10-15% silica. Male smokers and nonsmokers in the dust-exposed group had a higher prevalence of cough and chest tightness compared with those in the control group. Among dust-exposed workers, female nonsmokers had a significantly higher prevalence of cough, chronic bronchitis, chest tightness, and dyspnea than those in the control group. Lung function tests showed that dust-exposed workers had a greater incidence of abnormal lung function than did control workers, as measured by percentage of predicted forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), and FEV1.0/FVC. Dust exposure was the main cause of respiratory symptoms and abnormal values of FEV1.0, but both cigarette smoking and dust exposure contributed to the abnormal values reported for FEV1.0.     

The respiratory health of carbon black workers

The respiratory health of 3,027 carbon black workers employed in 19 plants (18 Western Europe, 1 U.S.A.) was assessed by questionnaire and spirometry; chest radiographs were used to assess 935 workers in the group. The results showed that the group of workers who were exposed to carbon black dust had an increased prevalence of chronic cough, sputum production and wheezing and the mean forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1.0) and flow between 25% and 75% of the FVC (MMEF 25-75%) were significantly less than those of the nonexposed group. Multiple regression analysis showed that the decline in respiratory health was related to the influence of smoking and age, with only a small part being associated with the combined effects of dust exposure and age. A simple type of pneumoconiosis was found in 6 of the workers, all of whom had more than 10 yr of dust exposure. Carbon black should be regarded as a nuisance dust without specific effect on the lungs.     

Dose responses of years of exposure on lung functions in flour mill workers

Flour dust is a heterogeneous substance with respiratory sensitizing properties; its long-term exposure may cause acute or chronic respiratory diseases. Therefore, the aim was to investigate the dose response effects of flour dust on lung function. An additional objective was to minimize the potential health risks in flour mill workers by providing them with information about the hazards of flour dust. Pulmonary function was studied in forty-six male flour mill workers who worked without the benefit of flour dust control ventilation or respiratory protective devices and a similar number of male control subjects. All participants were non-smokers and were matched for age, height, weight and socio-economic status. Pulmonary function tests were performed by using an electronic Spirometer and results were compared by a paired t-test. The present study results showed a significant decrease in the mean values of FVC, FEV(1), PEF and MVV and this impairment was increased with duration of exposure in the flour mills. This group of flour mill workers had occupationally related pulmonary function impairment and stratification of results showed a dose response of years of exposure in flour mills on lung function.     

Respiratory disease in a textile factory in Nicaragua

This is the first epidemiologic study conducted in a textile mill in Nicaragua using techniques and diagnostic criteria similar to those used in the United States and England. The prevalence of byssinosis and nonspecific respiratory symptoms were studied in 194 workers in a cotton mill in Managua. Limited environmental sampling, performed using a vertical elutriator in yarn preparation and weaving areas, indicated that exposures were similar to those reported in other parts of the developing world. A modified translated version of the Medical Research Council respiratory questionnaire was administered. Pulmonary function tests were performed before and after the Monday workshift to measure across-shift change in ventilatory function. The prevalence of byssinosis was 5.9% and all the cases occurred among exposed women. Nonspecific respiratory symptoms were also more prevalent among exposed workers. After adjusting for age, gender, smoking habit, and work tenure, the exposure odds ratios for usual cough and usual phlegm were 3.3 and 2.2, respectively. The association between exposure and across-shift decrement in FEV1 was not significant. Byssinotic workers, however, had greater decrements in FEV1% than those without byssinosis: 5.5% versus 1.8%. A consistent gender effect was observed in which both exposed and unexposed women were found to have greater across-shift decrements in FEV1 than men. The gender difference existed among long-term workers as well as workers who had been employed less than 2 years. Results are related to cotton dust exposure, as has been documented elsewhere. The poorer health status of the women in this study population deserves follow-up.     

Respiratory and allergic disorders in workers exposed to grain and flour dusts

Symptoms suggestive of chronic bronchitis or chronic productive cough were found in 29.0% of 100 workers exposed to flour dust in a flour mill, 26.0% presenting with chronic cough and 29.0% with phlegm. In the control group, the prevalence of chronic cough and phlegm was only 6.6% in each category. While 22.0% of the workers complained of chest tightness on exposure, and 18.0% developed symptoms and signs of bronchial asthma, only 3.3% of the controls complained of chest tightness and 3.3% of asthma. Respiratory measurements before and after the working shift showed a significant drop (p less than .001) in the forced expiratory volume in 1 sec (FEV1.0) and forced vital capacity (FVC) in the exposed group. Fifty-eight percent of the exposed workers experienced a drop in FEV1.0 and FVC measurements. A positive skin reaction to wheat flour extract was recorded among 31% of the exposed workers vs. 10% of the controls. The prevalence of other associated allergic symptoms was 17.0% and 19.0% for sinusitis and conjunctivitis, respectively; in the unexposed group, the prevalence of the same symptoms ranged between 3.3% and 6.6%. A strong association was revealed between exposure to grain and flour dusts and the prevalence of respiratory and allergic disorders.     

谷物粉尘对接尘工人呼吸系统影响的调查

本文对沈阳市某粮库进行了一次现场卫生学调查和接尘工人流行病学调查，发现该库生产环境空气中粉尘浓度超过国家标准．焦磷酸重量法测定粉尘中游离SiO2含量均在10％以上。接尘工人各种呼吸道症状阳性率较高，慢性支气管炎患病率为29．30％(吸烟者为30．50％，不吸烟者为22．45％)，谷物热发病率为15．61%。接尘工人FVC、V75、V50。和V25的异常率均非常显著地高于对照组。急性肺功能改变．接尘工龄不足10年组较10年以上组更明显，38例胸片无一例可诊断为尘肺。     

Occupational exposure to lignite and impact on respiratory system among heavy industry personnel

Objective is to evaluate the impact of occupational exposure to lignite dust on respiratory system. 103 blue-collar workers exposed to lignite dust and 62 controls completed a questionnaire on respiratory symptoms and underwent spirometry. Levels of lignite dust in workplace were measured. Univariate and multivariate analysis of the data were performed. The concentration of lignite dust varied from 0.6 to 1.4 mg/m3. Current smokers and workers exposed to lignite dust presented higher prevalence of chronic bronchitis symptoms and of FEV<80% and FEV1/FVC<70%. Multivariate analysis has shown that smoking and occupational exposure to lignite dust were independent predictors of chronic bronchitis symptoms, as well as of an obstructive ventilation pattern. Further analysis showed that exposed workers who were current smokers presented a five fold rate for developing an obstructive ventilation pattern in comparison to exposed workers non currently smokers. Occupational exposure to lignite dust and smoking were independent determinants of chronic bronchitis symptoms and obstructive ventilation pattern. There is some evidence for a combined effect of smoking and lignite dust exposure on respiratory system.     

Respiratory effects of inhalation exposure among workers during the clean-up effort at the World Trade Center disaster site

During December 2001 we conducted a field study of 183 clean-up and recovery workers at the World Trade Center (WTC) disaster site to assess respiratory health effects potentially resulting from their work at the site. On site, we administered a respiratory health questionnaire designed to assess upper respiratory symptoms and lower respiratory symptoms, including cough, phlegm, and wheeze, as well as indices of exposure, including number of days worked at the site and job category. Spirometry was conducted for 175 workers. Sixty-five percent of the workers surveyed arrived at the site without lower respiratory symptoms. Of this group, 34% developed cough, 24% developed phlegm, and 19% developed wheeze. Prevalence rates of these symptoms were related to the number of days spent working at the WTC, but not job category. The mean percentage predicted FEV(1) and FVC were 6% and 5% lower, respectively, for workers who developed new lower respiratory symptoms compared to those who remained symptom free. While the development of new wheeze suggested the presence of airway obstruction, the near-normal distribution of age-adjusted FEV(1)/FVC ratios suggested that the degree of obstruction was mild. The prevalence rates of upper airway symptoms (nasal congestion, sore throat, hoarse throat) exceeded those of lower respiratory symptoms, however, it was not determined whether symptoms pre-dated arrival at the WTC site.     

Exposure-response relationships for coal mine dust and obstructive lung disease following enactment of the Federal Coal Mine Health and Safety Act of 1969.

Underground U.S. coal miners were studied cross-sectionally for the association of respirable coal mine dust exposure with pulmonary function and symptoms of airways obstruction. The study group included 1,185 miners participating in Round 4 of the National Study of Coal Workers' Pneumoconiosis who had started mining in or after 1970 when comprehensive exposure regulations first came into effect. Quantitative estimates of cumulative exposure, derived using respirable dust measurements taken by the Mine Safety and Health Administration over the entire study period, were used in linear and logistic regression models on indicators of pulmonary function and chest symptoms while controlling for smoking status, pack-years, and other potential confounders. Statistically significant associations between log cumulative exposure and decrements in FVC, FEV1, and FEV1/FVC were observed. In logistic models, statistically significant associations of cumulative exposure with increasing prevalence of FEV1 and FEV1/FVC less than 80% predicted and symptoms including chronic phlegm, chronic bronchitis, breathlessness, wheeze, and wheeze with shortness of breath were found. It is concluded that exposures to respirable coal mine dust present in U.S. mines since 1970 continue to affect respiratory health in underground miners.     

Respiratory health status of gilsonite workers

Gilsonite, a solidified hydrocarbon used in the manufacture of automotive body seam sealers, is mined only in the Uinta Basin of Eastern Utah and Western Colorado. Health effects of gilsonite dust exposure have not previously been published and exposure to gilsonite dust is not regulated. To examine potential respiratory health effects associated with gilsonite dust exposures, this cross-sectional study surveyed the 100 current male employees who had been exposed to gilsonite dust at 3 existing gilsonite companies. Total dust exposures up to 28 times the nuisance dust standard were found, and 5 of 99 (5%) workers had chest radiographs consistent with pneumoconiosis of low profusion. Increased prevalences of cough and phlegm were found in workers with high-exposure jobs, but no evidence for dust-related pulmonary function impairment was noted. To prevent pulmonary health effects, we recommend reducing dust exposures for those workers in jobs currently characterized by relatively high dust exposures.     

Dust exposure and respiratory symptoms among cement factory workers in the United Arab Emirates

This study was conducted in a cement factory in the United Arab Emirates to assess cement dust exposure and its relationship to respiratory symptoms among workers. A total of 149 exposed and 78 unexposed workers participated in this cross-sectional study. Information on demographic and respiratory symptoms was collected by questionnaire. Personal total dust levels were determined by the gravimetric method. Concentration of the total dust ranged between 4.20 mg/m(3) in the crushers and 15.20 mg/m(3) in the packaging areas, and exceeded the exposure limit in the packaging and raw mill areas. The prevalence of respiratory symptoms was higher among the exposed workers, but the difference from that of unexposed workers was statistically significant only for cough (19.5%; OR=4.5; 95%CI=1.5-13.2), and phlegm (14.8%; OR=13.3; 95%CI=1.8-100.9). Cough and phlegm were found to be related to exposure to dust, cumulative dust and smoking habit, while chronic bronchitis was related to smoking habit. The few factory workers (19.5%) who used masks all the time had a lower prevalence rate of respiratory symptoms than those not using them. High dust level was the only variable that influenced the workers to use the mask all the time. It is recommended that control measures be adopted to reduce the dust and workers should be encouraged to use respiratory protection devices during their working time.     

汽车制造业铸造作业工人职业健康状况分析

目的了解汽车制造业铸造粉尘对作业工人健康的影响。方法选择汽车制造业230名铸造工人为接尘组和200名非接触尘毒职工为对照组,通过职业健康体检,比较两组的健康状况。同时测定生产环境中粉尘浓度及二氧化硅含量。结果生产环境粉尘中游离SiO2含量为12.2%￣85.3%,粉尘浓度0.5￣1.75mg/m3,合格率为80%;接尘组工人自觉症状中咳嗽、咯痰、气短阳性率及体检项目中慢性咽炎、慢性鼻炎检出率均明显高于对照组(P<0.05或P<0.01);接尘组肺功能指标(FEF25%￣75%、FEF75%)均低于对照组(P<0.05);小气道功能异常率接尘组为8.3%,对照组为2.5%,两组比较,差异有显著性(P<0.01)。结论汽车制造业铸造粉尘可影响作业工人的健康,尤其对呼吸系统损害更明显,应加强防护措施。