Cigarette smoking and small irregular opacities.

A survey of chemical workers by chest roentgenograms was designed to determine whether exposure to acrylic dust and/or cigarette smoking was associated with diffuse abnormalities suggestive of pneumoconiosis. The films were examined without knowledge of dust exposure or smoking habits. The International Labour Office (ILO) classification and standard films were used. Workers with exposure to asbestos were excluded. There was no relation between prevalence of abnormalities and exposure to dust. Among 181 workers 28 had s and/or t small irregular opacities with profusion of 0/1 (23), 1/0 (three), or 1/1 (two). These findings were present in 20% of smokers compared with 2.2% of non-smokers. The prevalence increased with increasing age to 31.6% among smokers aged 50-64. Prevalence was 10% among ex-smokers of cigarettes. Among current cigarette smokers, prevalence was 5.3% in those who smoked less than one pack per day, 31.3% in heavier cigarette smokers, and 52.9% in 17 heavy cigarette smokers aged 50-64. Profusions of 0/1 and 1/0 are classified as "suspect" pneumoconiosis according to the ILO guidelines. The data in this study indicate that such abnormalities are directly related to age and smoking habits among workers not exposed to hazardous dust.     

Respiratory abnormalities among male foundry workers in central Taiwan

The objectives of this study were to determine the relationship between exposure levels and respiratory abnormalities, to measure FVC and FEV1(1) changes per year based on work duties and to investigate the prevalence of and factors related to pneumoconiosis. A total of 583 male workers from 50 iron foundries in central Taiwan were investigated. First, workers' respiratory symptoms were categorized using a modified American Thoracic Society (ATS) questionnaire and then were verified by physician's examination. Next, pulmonary function tests were performed including: forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and forced expiratory flow rate. A chest radiograph was used to diagnose pneumoconiosis according to ILO criteria. Furnace workers were found to have the highest prevalence of chronic phlegm, thoracic disorders and chronic bronchitis. In general, smokers had a higher prevalence of respiratory symptoms as compared with non-smokers. Pulmonary function abnormalities and pneumoconiosis were closely linked to smoking and work duration. After adjusting for age, height and smoking there was a significant decrease based on work duration in FVC and FEV1 for furnace and moulding workers compared with after-processing and administrative workers. The overall prevalence of pneumoconiosis was 8.8%, highest among furnace (16.3%) and after-processing workers (11.4%) and lowest among administrative workers (2.5%). Using multiple logistic regression, the risk of developing pneumoconiosis (as compared with the administrative workers) for furnace workers was highest (8.98 times greater risk), followed by after-processing workers (6.77 times greater risk) and moulding workers (5.41 times greater risk). Prolonged exposure to free silica, and smoking habits, can result in respiratory abnormalities among foundry workers.     

Radiographic abnormalities among construction workers exposed to quartz containing dust

Background: Construction workers are exposed to quartz containing respirable dust, at levels that may cause fibrosis in the lungs. Studies so far have not established a dose-response relation for radiographic abnormalities for this occupational group.

Aims: To measure the extent of radiographic abnormalities among construction workers primarily exposed to quartz containing respirable dust.

Methods: A cross sectional study on radiographic abnormalities indicative of pneumoconiosis was conducted among 1339 construction workers mainly involved in grinding, (jack)-hammering, drilling, cutting, sawing, and polishing. Radiological abnormalities were determined by median results of the 1980 International Labour Organisation system of three certified "B" readers. Questionnaires were used for assessment of occupational history, presence of respiratory diseases, and symptoms and smoking habits.

Results: An abnormality of ILO profusion category 1/0 and greater was observed on 10.2% of the chest radiographs, and profusion category of 1/1 or greater on 2.9% of the radiographs. The average duration of exposure of this group was 19 years and the average age was 42. The predominant type of small opacities (irregularly shaped) is presumably indicative of mixed dust pneumoconiosis. The prevalence of early signs of nodular silicosis (small rounded opacities of category 1/0 or greater) was low (0.8%).

Conclusions: The study suggests an elevated risk of radiographic abnormalities among these workers with expected high exposure. An association between radiographic abnormalities and cumulative exposure to quartz containing dust from construction sites was observed, after correction for potentially confounding variables.

     

Lung disorders of workers exposed to rush smear dust in China

The aim of this study was to evaluate the lung disorders of the workers exposed to rush smear dust. A cross sectional study was carried out on 1,709 current workers (788 male, 921 female) in 80 factories. All subjects were asked by questionnaire, and health examination including chest X-ray was conducted for 661 workers in 35 factories. Lung function test was also examined for 119 non-smoking males among 661 subjects. Dust samplings were collected and total and respirable dust concentrations at 127 spots in 35 factories were measured. The geometric mean dust concentration in the workshops was up to 20.00 mg/m(3), and the geometric mean respirable dust concentration reached 8.22 mg/m(3). The mean quartz concentration of accumulated dust was 29.2%. The prevalence of radiographic small opacities profusion category > or = 1/0, according to the ILO 1980 Classification System, was 2.6% among 661 employees. One worker was found to have pneumoconiotic findings of 2/2 profusion accompanied with large opacity. The prevalence of pneumoconiosis (1/0 or more) correlated with cumulative dust exposure (r=0.192, p<0.0001). The similar relationship was found between the prevalence rate of cough or sputa and worksite dust concentration. In non-smokers, a positive association was found between the prevalence of cough and occupational exposure duration (r=0.080, p=0.004). Approximately 19.3% and 34.5% of employees suffered from respiratory impairment for FVC and FEV1.0, respectively. This is the first report of "rush" pneumoconiosis in China. Rush mat workers were found to be at high risk for pneumoconiosis, a preventable disease. Our results showed a dose-response relationship between rush-mat dust level and the prevalence of pneumoconiosis. Similar relationship between the prevalence of cough and sputum and the work duration was found for non-smoking workers but not for smoking workers.     

Respiratory symptoms, lung function, and pneumoconiosis among self employed dental technicians.

From the registry of self employed workers living in Paris, a group of 105 dental technicians was studied to evaluate occupational exposure, to determine respiratory manifestations, and to investigate immune disturbances. Seventy one dental technicians (age range 43-68: group D), 34 dental technicians younger than 43 or older than 68 (group d), and 68 control workers (age range 43-66: group C) were investigated. The demographic characteristics and the smoking habits of the groups D and C did not differ significantly. The dental technicians often worked alone (43.7%) or in small laboratories without adequate dust control. The mean duration of their exposure was long (group D 34.0 (SD 8.4) years). The prevalence of respiratory symptoms did not differ between groups D and C except for the occurrence of increased cough and phlegm lasting for three weeks or more over the past three years (group D 16.9%, group C 2.9%, p < 0.007). The effect of cigarette smoking on respiratory symptoms and lung function was obvious. All mean values of lung function for dental technicians and controls were within normal limits. Significant decreases in all mean lung function values were found among smokers by comparison with non-smokers, however, and a positive interaction with occupational exposure was established. The x ray films of dental technicians (n = 102, groups D and d) were read independently by four readers and recorded according to the International Labour Office classification of pneumoconioses. The prevalence of small opacities greater than 1/0 was 11.8% with a significant increase with duration of exposure. The prevalence among dental technicians with 30 years or exposure or more was significantly higher (22.2%) than those with less than 30 years (3.5, p < 0.004). The prevalence of autoantibodies (rheumatoid factors, antinuclear antibodies, and antihistone antibodies) was not significantly different in the groups D and C. When positive, autoantibodies only occurred at low concentrations. This finding contrasts with previous reports on the occurrence of autoantibodies and even of connective tissue diseases in dental technicians. In conclusion, the study confirms an increased risk of pneumoconiosis among dental technicians. Moreover, there may be other lung disorders such as impairment of lung function especially in association with cigarette smoking.     

The study of byssinosis in China: a comprehensive report

Cross-sectional studies were conducted during 1981-1983 among 861 textile workers in 3 cotton mills and 822 controls in 2 silk factories. Questionnaire and lung function tests were taken and inhalable dust concentrations were measured. Prevalence of byssinosis was 5.6%. Average dust concentrations were highest in carding rooms, 1.47-1.99 mg/m3. The correlations (r) between prevalence of byssinosis and dust concentrations was 0.64 (p less than 0.05). The prevalence of chronic bronchitis was 14.4% in cotton workers and 5.1% in controls (p less than 0.05). Acute FEV1 percent decrement (greater than 5%) was higher among cotton workers (32.1%) compared to controls (14.5%) (p less than 0.001). In one cotton blanket factory, the prevalence of byssinosis and chronic bronchitis was higher among workers in the high-dust work areas. Long-term effect studies included pulmonary function test among 173 cotton workers and 373 controls, retired 1-10 years, using the flow volume curve (FVC); chest X-rays of 140 pairs of cotton workers and controls with working tenures over 20 years; and examination of lobectomy specimens of 8 textile workers matched with 16 controls. In male cotton workers, only smokers had a prominent decrement of lung function indices, except FVC. For non-smoking females, there was no difference between the two groups. Additive effects were seen between smoking and dust exposure. According to the International Labor Organization (ILO) Pneumoconiosis Classification, the prevalence of abnormality (profusion greater than 1/0) was 4.3% and 8.7% in non-smoking controls and cotton workers. The interstitial changes on X-ray due to smoking would be much heavier. Additive effects also existed between smoking and dust exposures. No significant changes attributable to dust exposure were seen on pathological section of lobectomy specimens.     

Smoking prevalence, behaviour and nicotine addiction among coal workers in Zonguldak, Turkey

To assess the smoking status of coal workers, as coal dust exposure and concomitant cigarette smoking contribute to the increased prevalence of pulmonary interstitial fibrosis, chronic obstructive pulmonary disease and other pulmonary diseases. A survey was conducted to determine the smoking prevalence, behaviour and nicotine addiction in coal workers. The target population consisted of 475 underground coal workers who lived in Zonguldak city of Turkey, and we reached 389 of them. Each subject completed a detailed smoking history questionnaire (included 56 question). Chest X-rays and pulmonary function tests were performed to evaluate patients' related diseases and complications. Smoking status of the workers was as follows; Sixty-nine never smokers (17.7%), 62 ex-smokers (15.9%) and 258 current smokers (66.3%). The mean age of starting smoking was similar among ex and current smokers (15.9 +/- 4.2 versus 15.0 +/- 4.0). The most common reason for starting smoking was smoking interest (50%) and friends' influence (15.5%). The most frequent reason stated for successful smoking cessation was experience of smoking-related symptoms or development of a medical condition (51%). The most important reason given by current smokers for smoking cessation attempts was increased chance of developing lung cancer, pneumoconiosis and other diseases (22.9%). Nicotine addiction was assessed by the Fagerstroem test. Mild (0-3 points), moderate (4-6) and severe (7 or more) addiction ratios were found to be 39.1%, 44.2% and 16.7% respectively. Ex-smokers had the highest prevalence of large and small airway obstruction on spirometry. Smoking prevalence is high in coal workers living in Zonguldak city of Turkey. Most of the smokers know that smoking is dangerous and want to quit smoking. A detailed smoking history during medical surveillance may help the occupational physician to develop a system in which such individuals can be referred to comprehensive smoking cessation programs.     

蔺草染土粉尘对工人健康影响的研究

目的　研究蔺草染土粉尘对工人健康的影响。方法　采用横断面整群抽样 ,对所选工厂进行劳动卫生学调查 ,并对 6 6 1名作业工人进行问卷和健康检查。结果　蔺草加工业主要引起严重的粉尘污染 ,总尘平均浓度为 2 0 .0 0mg/m3 ,呼吸性粉尘平均浓度为 8.2 2mg/m3 。车间积尘平均游离SiO2 含量为 2 5 .6 %。在作业工人中发现Ⅰ期及以上蔺草染土尘肺 9例 [其中Ⅱ期 1例 (小阴影聚集 ) ]、0 + 8例 ;X线胸片阳性 (1/0以上 )检出率为 2 .5 7%,与接尘工龄、粉尘浓度密切相关 (分别为r =1.15 6 ,P <0 .0 0 1;r =0 .10 6 ,P =0 .0 0 6 ) ;咳嗽、咯痰等症状与接触蔺草染土粉尘有趋势相关 (分别为r=0 .0 85 ,P =0 .0 2 8;r=0 .0 94,P =0 .0 16 )。结论　蔺草染土尘肺在我国首次报道 ,作业工人肺X线胸片阳性检出率与接触蔺草染土粉尘存在一定的剂量 -效应关系 ;工人咳嗽、咯痰与粉尘接触有关。蔺草染土致尘肺的机制有待于进一步调查。     

A case-control study to investigate the association between indices of dust exposure and the development of radiologic pneumoconiosis

A case-control study on employees at an iron ore surface mining plant was undertaken to determine which indices of occupational dust exposure related most closely to radiologic categories for pneumoconiosis. Forty cases, with radiographs compatible with the ILO Categories (1980) for simple pneumoconiosis, were matched for age, smoking habit, and date of entry into the workforce with 80 control subjects whose radiographs were read as normal. The six indices of dust exposure were cumulative and "peak" respirable dust, quartz, and iron oxide. Both iron oxide indices were not significant at the 5% level for either ILO Category 1 or Categories 2,3. The association between dust composition and ILO radiologic category for simple pneumoconiosis was consistent, with respirable quartz being the best differentiating index between the case and control groups.     

Respiratory Status of Surface Coal Miners in the United States

The United States Public Health Service examined 1,438 surface coal miners to determine the prevalence of coal worker’s pneumoconiosis (CWP), chronic bronchitis, and ventilatory impairment among them. Four percent (fifty-nine individuals) showed some roentgenographic evidence of pneumoconiosis, but only seven miners had films interpreted as CWP of category2 or greater (according to the UlCC/Cincinnati classification system). Moreover, most of the affected miners had worked in underground coal mines for prolonged periods. Significant decrements in pulmonary function to increasing exposure to surface mine dust were demonstrated only in the forced vital capacity of smokers. Increased prevalence of chronic bronchitis with increasing exposure was found in all smoking categories. However, significant airway obstruction was an uncommon finding (6.6%) in nonsmoking miners. Employment in surface mining was not likely to cause either the development of CWP or clinically significant respiratory impairment.     

Silicosis in a grey iron foundry. The persistence of an ancient disease

An industrial hygiene and medical survey was conducted in an iron foundry to study the occurrence of silicosis. Breathing zone exposures to respirable crystalline silica had been very high in 1977 [1 045 micrograms/m3 (geometric mean) for coremakers and 198 micrograms/m3 for fettlers]; exposures in 1980 and 1982 were substantially lower. A radiographic evaluation of 188 workers revealed silicosis in 18 (9.6%). Eight had category 1 profusion of small rounded pulmonary lesions (by the 1980 classification of the International Labour Office); two had category 2; and eight had category 3. Two had progressive massive fibrosis. Four workers without silicosis in 1977 had developed lesions by 1980. The prevalence increased from 1.5% among workers employed less than 20 years to 53% among longer term workers. No association was found between the prevalence of silicosis and cigarette smoking. Chronic cough was more common in workers with heavy current dust exposure than in those with light exposure, more common in smokers than in nonsmokers, and more common in silicotics than in nonsilicotics. A multiplicative interaction existed between dust exposure and smoking in the etiology of cough. Silicosis continues to exist in American foundries. Cigarette smoking does not contribute to the causation of silicosis, but it aggravates the attendant respiratory symptoms.     

Evaluation of serum type III procollagen peptide as an exposure marker in retired coal workers

Serum type III procollagen peptide (PIIIP), a degradation product of the type III collagen precursor, has been put forward as an exposure marker for mineral dust. We evaluated PIIIP levels as a marker of exposure to and effects of coal dust in retired coal miners (n = 104). To this end: (a) the individual cumulative dust exposure was calculated from job-exposure matrices, and (b) in addition to routine chest radiography (CR) of all miners according to the criteria of the International Labour Organisation (ILO), a subgroup (n = 46) was screened by high-resolution computed tomography (HRCT). Profusion score (CR and HRCT) tended to increase with cumulative dust exposure, even in the absence of CR evidence for pneumoconiosis (i.e. CR , 0/1, n = 35). In contrast to our previous findings in active miners, PIIIP levels were not increased in miners as compared with non-dust-exposed controls (n = 29), and no differences were observed between miners without (ILO = 0/0) and miners with coal workers' pneumoconiosis (CWP; ILO 0/1). No trend in PIIIP versus pneumoconiosis stage was present, either by CR or by the more sensitive HRCT score. PIIIP was also unrelated to any lung function parameter (FEV₁, FVC, impedance, diffusion capacity). Age, medication, medical history and smoking habits had no significant effect on PIIIP levels. In the miners with CWP (i.e. ILO > 0/0, n = 28) a significant negative correlation was present between PIIIP values and (log) cumulative dust exposure. This decrease in serum PIIIP levels with increasing cumulative exposure may be due to chronic adaptive changes in type III collagen deposition and/or breakdown. Other relations between exposure and PIIIP were not observed. In conclusion, the present findings do not support the use of serum type III procollagen peptide as a marker of exposure to and (early) interstitial or respiratory effects of coal dust.     

Respiratory Function and Disease among Workers in Alkaline Dusts

Little is known of the possible effects of sodium carbonate dust on the lower respiratory passages. A large alkali industry, with a number of works, was used for an investigation of lime and soda ash dusts evolved during the process. The physical and chemical characteristics of these dusts and details of the type of work and environmental conditions are described. In 1954 and 1956 a survey was made of respiratory sickness absence, chest radiographic appearance, and respiratory function in workers employed in areas with exposure to soda ash, lime dust, and no dust. All were interrogated about their smoking habits. In 1954 there was found to be a significant reduction in expiratory flow rate of workers in dusty jobs in soda ash compared with the group not exposed to dust but this result was nullified in a random sample group in 1955 and in full groups in 1956. Respiratory sickness absence was found to be slightly greater in workers in dusty occupations, particularly in lime dust. No pneumoconiosis was detected on miniature films. The survey of smoking habits revealed that smoking was associated with a definite decrease in the expiratory flow rate, particularly after the age of 40 in heavy smokers. It was concluded that smoking habits played a more important part than alkaline dusts in the reduction of respiratory efficiency as measured by a study of sickness absence and performance of a simple spirometric test.     

Pneumoconiosis among workers in a Vietnamese refractory brick facility

BACKGROUND: Vietnam is a rapidly industrializing country with increasing needs for building materials, including refractory bricks. The manufacture of refractory bricks results in high levels of free silica, a recognized occupational hazard. METHODS: A cross-sectional survey was conducted among 158 employees using a respiratory symptom questionnaire and ILO classification of radiographs for pneumoconiosis. RESULTS: The prevalence of radiographic silicosis (ILO category 1/0 and greater) was 10% in all workers with evidence of a dose-response gradient. Pneumoconiosis prevalence increased from 0% in workers employed < 10 years at the plant to 18% for workers employed > 20 years (trend test P = 0.01 for each year increment after adjusting for gender and tobacco use). CONCLUSIONS: Workers in this plant demonstrate a consistent pattern of radiographic evidence of pneumoconiosis, which appears to be related to duration of work. Future studies should assess exposure control measures that are appropriate to countries undergoing rapid industrialization such as Vietnam.     

Pneumoconiosis in Cornish china clay workers.

A radiological survey of men employed in the china clay industry in Cornwall was carried out in 1977. Each man completed a short questionnaire on respiratory symptoms and smoking habits, his occupational history was determined, and his forced expiratory volume and vital capacity were measured. The radiographs were read independently by three observers, using the 1980 ILO classification. Of the 1728 men in the study, 23 had had dust exposure elsewhere, mostly in tin mining, and were excluded. Readings of the radiographs were available for 1676 men: 77.4% were within category 0, 17.9% in category 1, and 4.7% in categories 2 and 3. In 19 men (1.1%) one or more readers recorded the presence of a large shadow and read it as complicated pneumoconiosis, but in only four men were the readers unanimous. Every job recognised as dusty contributed significantly to the amount of simple pneumoconiosis, and in two jobs the conditions were such that the average worker would reach category 2 in a working lifetime. Smoking appeared unrelated to the radiographic appearance. Vital capacity showed a significant reduction with increasing amount of pneumoconiosis, but not, when this was allowed for, on the duration of exposure in any of the job categories. In addition it depended, as would be expected, on smoking. The effect of one category increase in pneumoconiosis was equivalent to 4.1 years of age in smokers, 3.9 years of age in ex-smokers, and 5.4 years of age in non-smoker. Forced expiratory volume did not decline significantly with amount of pneumoconiosis, so that FEV% VC showed an increase, though not to a significant extent. No extent. No relationship between symptoms and past exposure was detected.     

Pulmonary effects of exposure to fine fibreglass: irregular opacities and small airways obstruction.

OBJECTIVE--Man made mineral fibres imitate asbestos and produce tumours of the pleura in animals. To answer the question, Does prolonged exposure to fibreglass adversely affect pulmonary function or produce radiographic abnormalities in human subjects? we studied workers in a midwestern appliance plant where refrigerator doors and previously entire cabinets were insulated with fibreglass sheeting and loose rotary spun fibreglass. METHODS--Spirometry and lung volumes were measured, respiratory and occupational questionnaires were administered, and chest x-ray films were read for pneumoconiosis using International Labour Office (ILO) 1980 criteria in 284 workers with exposure of 20 years or more. RESULTS--Expiratory flows were reduced including FEV1 (mean 90.3% of predicted (pr), FEF25-75 (85.5% pr), and FEF75-85 (76.2% pr). Forced vital capacity was significantly reduced (92.8% pr) and total lung capacity was significantly increased (109.2% pr). In white male smokers, a group large enough for comparisons, parameters of pulmonary function were reduced further in the presence of irregular opacities. Forty three workers (15.1%) had evidence of pneumoconiosis on chest radiographs: 26 of these (9.1%), had no known exposure to asbestos and 17 (6.0%) had some exposure. The best judgement was that in 36 (13.0%), pulmonary opacities or pleural abnormalities were due to fibreglass. CONCLUSION--Commercial rotary spun fibreglass used for insulating appliances appears to produce human disease that is similar to asbestosis.     

Pulmonary effects of exposure to fine fibreglass: irregular opacities and small airways obstruction.

OBJECTIVE--Man made mineral fibres imitate asbestos and produce tumours of the pleura in animals. To answer the question, Does prolonged exposure to fibreglass adversely affect pulmonary function or produce radiographic abnormalities in human subjects? we studied workers in a midwestern appliance plant where refrigerator doors and previously entire cabinets were insulated with fibreglass sheeting and loose rotary spun fibreglass. METHODS--Spirometry and lung volumes were measured, respiratory and occupational questionnaires were administered, and chest x-ray films were read for pneumoconiosis using International Labour Office (ILO) 1980 criteria in 284 workers with exposure of 20 years or more. RESULTS--Expiratory flows were reduced including FEV1 (mean 90.3% of predicted (pr), FEF25-75 (85.5% pr), and FEF75-85 (76.2% pr). Forced vital capacity was significantly reduced (92.8% pr) and total lung capacity was significantly increased (109.2% pr). In white male smokers, a group large enough for comparisons, parameters of pulmonary function were reduced further in the presence of irregular opacities. Forty three workers (15.1%) had evidence of pneumoconiosis on chest radiographs: 26 of these (9.1%), had no known exposure to asbestos and 17 (6.0%) had some exposure. The best judgement was that in 36 (13.0%), pulmonary opacities or pleural abnormalities were due to fibreglass. CONCLUSION--Commercial rotary spun fibreglass used for insulating appliances appears to produce human disease that is similar to asbestosis.     

Intrapulmonary reactions of workers exposed to dust and ozone

Forty-one dust-and-ozone-exposed and 37 nonexposed workers, belonging to the Research and Development Division of a photo-copier manufacturing industry, were examined to assess the effect of the exposure to carbon, iron and resin dust and ozone in the air of the work environment by means of questionnaires on their physical condition, smoking habits and exposure history by interview, chest X-rays, testing of ventilatory functions, transcutaneous PO2 (tcPO2) test and H2O2-induced hemolysis test. The following results were obtained. Respirable dust concentrations in the air of the work place were 0.1-1.0 mg/m3, total dust concentrations 0.2-2.0 mg/m3, and ozone concentrations 0.004-0.06 ppm (0.008-0.12 mg/m3). According to the Japanese Classification of Radiographs of Pneumoconioses, the exposed workers showed a higher rate of profusion 0/1 and over, and category 1 and over (1/0 and over) than the nonexposed workers. Ventilatory function testing revealed no difference between exposed workers and nonexposed workers, but small airway narrowing was suspected in smoking workers in comparison with nonsmoking workers. Transcutaneous PO2 showed no difference between exposed and nonexposed workers, between smoking and nonsmoking workers, and between any of the paired six combinations out of the four groups of workers, i.e., nonsmoking and nonexposed, nonsmoking and exposed, smoking and nonexposed, and smoking and exposed. It was estimated by H2O2-induced hemolysis test that smoking and/or dust exposure, especially long-term exposure, gave rise to aggravation of fragility of the erythrocyte membrane by lipid peroxidation with ozone or active oxygen produced by the reaction of dust and alveolar macrophages. The questionnaire was considered indispensable to ascertain the workers' exposure history. No worker in this work environment showed clinical signs indicating a need for medical care or home response. There results may indicate that in resolving the pathogenesis of pneumoconiosis further studies will be required on the prevalence rate of profusion 0/1 and over (or category 1 and over) under low concentrations of dust exposure and on the intrapulmonary reactions induced by low doses of dust exposure.     

大冶铁矿尘肺发病规律及其影响因素

[目的]分析武钢大冶铁矿尘肺发病规律,探讨尘肺发病的主要影响因素。[方法]选择该铁矿1960～1974年间登记在册且工作过1年以上的所有工人建立研究队列,随访至2003年底。收集队列成员的基本资料、职业史、疾病史及各工种历年的粉尘浓度监测资料,分析铁矿尘肺的发病规律。随机选取1714名存活的队列成员,测定TNF-α-308位点及hOGG1Ser326Cys多态性。计算各影响因素对尘肺发病的相对危险度（RR）。[结果]队列共7666人,到2003年底共随访261410.72人年,失访275人。接尘工人3604人,共随访126863.13人年,诊断314例尘肺,尘肺发病率为0.25%,累计发病率8.71%。75.80%的尘肺病例1960年之前开始接尘,83.12%的病例累积接尘量大于50mg（/m^3·a）。铁矿尘肺的平均潜伏期19.65年,77.71%的病例潜伏期在10～30年之间。发病率随着累积接尘量的增加而升高,高、中接尘组相对于低接尘组的RR分别为8.25和2.27;吸烟组尘肺发病率是不吸烟组的1.7倍;肺结核组发生尘肺危险较非肺结核组明显增高（RR=32.34）;TNF-α-308位点及hOGG1Ser326Cys的突变型和野生纯合子组间发病情况差异无统计学意义（P〉0．05）.[结论]累积接尘量高是影响铁矿尘肺发病的根本因素,吸烟和患肺结核可促进其发生。TNF-α-308位点及hOGGISer326Cys多态性在铁矿尘肺的发病中不起主要作用。     

Parenchymal and pleural fibrosis in construction workers.

Exposure to mineral dust was studied among construction workers (N = 437) with the aid of a questionnaire and a chest X-ray examination of the lungs. The results of the questionnaire showed that 81% of the construction workers had been exposed to asbestos. Exposure had occurred in all of the occupational groups studied. Pleural plaques and/or lung fibrosis (ILO greater than or equal to 1/1) were found in 26% of the examined workers; the prevalence varied from 18 to 40% among the various occupational groups. Comparison with a representative sample of the Finnish male population from another investigation indicates that the frequency of lung fibrosis (ILO greater than or equal to 1/1) is at least two times higher among the examined construction workers than among the general population. It seems likely that exposure to asbestos dust can be considered an etiological factor for an appreciable number of the X-ray findings.