Nonmalignant mortality among workers in six Norwegian aluminum plants

OBJECTIVES: This study investigated the associations between exposure to fluorides and polycyclic aromatic hydrocarbons (PAH) and mortality from nonmalignant diseases among workers in the Norwegian primary aluminum industry. METHODS: Mortality among 10,857 men, employed for more than 3 years in 1 of 6 aluminum plants, was investigated from 1962 to 1996, giving 239,246 person-years during follow-up. Ajob-exposure matrix covering all 6 plants was used to estimate the individual exposure to total fluorides and particulate PAH. The observed cause-specific deaths were compared with expected figures calculated from national rates. Dose-response relations were investigated by internal comparisons using Poisson regression and by stratified analyses for standardized mortality ratio. Potential confounding by smoking was investigated in subanalyses restricted to 3 of the plants for which information on smoking habits was accessible. RESULTS: Mortality from circulatory disease was slightly lower than expected [SMR 0.95, 95% confidence interval (95%CI) 0.9-1.0], while there was an increased mortality from asthma, emphysema, and chronic bronchitis combined, SMR 1.2 (95% CI 1.0-1.5). Mortality from these diseases was associated with cumulative exposure to fluorides. The rate ratio in the internal analysis rose steadily to 2.5 (95% CI 1.5-4.3) for the upper exposure category. No association was observed between cumulative fluoride exposure or PAH exposure and circulatory mortality. CONCLUSIONS: The study showed an association between exposure to potroom emissions measured by fluorides and mortality from asthma, emphysema, and chronic bronchitis combined.     

Skin and respiratory symptoms among workers with suspected work-related disease

Background Many workers are exposed to chemicals that can cause both respiratory and skin responses. Although there has been much work on respiratory and skin outcomes individually, there are few published studies examining lung and skin outcomes together. Aims To identify predictors of reporting concurrent skin and respiratory symptoms in a clinical population. Methods Patients with possible work-related skin or respiratory disease were recruited. An interviewer- administered questionnaire collected data on skin and respiratory symptoms, health history, smoking habits, workplace characteristics and occupational exposures. Predictors of concurrent skin and respiratory symptoms were identified using multiple logistic regression models adjusted for age, sex and atopy. Results In total, 204 subjects participated; 46% of the subjects were female and the mean age was 45.4 years (SD = 10.5). Most subjects (n = 167, 82%) had possible work-related skin disease, compared with 37 (18%) subjects with possible work-related respiratory disease. Subjects with a history of eczema (OR 3.68, 95% CI 1.7-7.8), those from larger workplaces (OR 2.82, 95% CI 1.8-7.4) and those reporting respirator use at work (OR 2.44, 95% CI 1.2-4.8) had significantly greater odds of reporting both work-related skin and respiratory symptoms. Current smoking was also associated with reporting concurrent skin and respiratory symptoms (OR 2.57, 95% CI 1.2-5.8). Conclusions Workers reported symptoms in both systems, and this may be under-recognised both in the workplace and the clinic. The association between history of eczema and concurrent skin and respiratory symptoms suggests a role for impaired barrier function but needs further investigation.     

Nonmalignant respiratory disease mortality among woodworkers participating in the American Cancer Society Cancer Prevention Study-II (CPS-II)

Nonmalignant respiratory disease (NMRD) mortality was examined among woodworkers participating in the American Cancer Society's CPS-II cohort study. During the 6-year prospective follow-up, there were 97 NMRD deaths among 11,541 men reporting employment in wood-related occupations and 1,338 NMRD deaths among 317,424 men reporting no exposure to wood dust or wood-related jobs. Relative risks, adjusted for age and smoking, were calculated using Poisson regression. A small excess of NMRD was observed among woodworkers. However, the relative risk was higher among woodworkers who did not report exposure to wood dust (RR = 1.52, 95% CI = 1.18–1.97) than those who did (RR = 1.27, 95% CI = 0.91–1.77), and no clear trend with duration of exposure was observed. An excess of NMRD was observed among woodworkers reporting exposure to asbestos (RR = 1.59, 95% CI = 0.85–2.96), as well as the small number of woodworkers reporting exposure to formaldehyde (RR = 1.95, 95% CI = 0.63–6.06), but men not reporting exposure to these substances also had an excess risk. Although limited by a short follow-up period and crude indicators of exposure, the strengths of this analysis were the ability to compare woodworkers to a similar, healthy population and to adjust for the effects of smoking. Cohort studies with better exposure information are needed to examine the role of occupational exposures among woodworkers in the etiology of respiratory disease. Am. J. Ind. Med. 34:238–243, 1998. © 1998 Wiley-Liss, Inc.     

Silicosis among former copper mine workers

There is a dearth of Brazilian studies analyzing the effect of ongoing exposure to silica among former copper mine workers, as radiographic readings for silicosis have received widespread medical attention. The scope of this study is to investigate the clinical and radiological manifestations of silicosis among former copper mine workers. A sample of 100 former copper miners had their clinical and occupational histories recorded and underwent chest radiography in a cross-sectional study that included personal interviews in which their age, sex and time worked in copper extraction were recorded. Patients with recent chest X-Rays brought them with them, or they signed a term of consent and X-Rays were taken and analyzed by the radiologist using the Student t Test and Pearson test. Among the 100 miners, 35% had silicosis, 11% had conditions other than silicosis, such as tuberculosis, emphysema, chronic pulmonary obstructive disease, and 54% had no pulmonary lesions. The high incidence of silicosis reinforces the recommendation that exposure should be halted as soon as an X-ray detects the condition.     

Environmental mycological study and allergic respiratory disease among tobacco processing workers

This study presents the results of an investigation of respiratory symptoms, lung function, chest X-ray examinations, analysis of specific IgE antibodies and skin prick tests to fungi on 130 tobacco-processing workers and 112 control workers. Industrial hygiene survey and environmental mycological studies were also performed. The average dust concentrations ranged from 13.76 to 29.55 mg/m(3) in the tobacco processing workshops. Also, the numbers of fungi colonies in the processing environments were much higher than those in the control environments. The prevalences of chronic respiratory or nasal symptoms in exposed workers were significantly higher than those in control workers (p<0.05 or p<0.01). The prevalences of lung function abnormalities in the exposed workers were significantly higher than those in control workers (p<0.05). The positive prevalences of specific IgE reactions to fungi (26.92% for A.fumigatus and 51.54% for Rhizopus nigricans) in exposed workers were also significantly higher than those in control workers (p<0.01). The positive prevalences of the skin prick test showed that 18.46% of the exposed workers were positive to A. fumigatus and 23.85% were positive to Rhizopus nigricans. Our results suggested that tobacco processing workers may develop respiratory diseases related to tobacco dust and we consider that fungi might be one of the allergens causing allergic respiratory or nasal diseases in tobacco processing workers.     

Nonmalignant respiratory effects of chronic arsenic exposure from drinking water among never-smokers in Bangladesh

BACKGROUND: Arsenic from drinking water has been associated with malignant and nonmalignant respiratory illnesses. The association with nonmalignant respiratory illnesses has not been well established because the assessments of respiratory symptoms may be influenced by recall bias or interviewer bias because participants had visible skin lesions. OBJECTIVES: We examined the relationship of the serum level of Clara cell protein CC16--a novel biomarker for respiratory illnesses--with well As, total urinary As, and urinary As methylation indices. METHODS: We conducted a cross-sectional study in nonsmoking individuals (n = 241) selected from a large cohort with a wide range of As exposure (0.1-761 microg/L) from drinking water in Bangladesh. Total urinary As, urinary As metabolites, and serum CC16 were measured in urine and serum samples collected at baseline of the parent cohort study. RESULTS: We observed an inverse association between urinary As and serum CC16 among persons with skin lesions (beta = -0.13, p = 0.01). We also observed a positive association between secondary methylation index in urinary As and CC16 levels (beta = 0.12, p = 0.05) in the overall study population; the association was stronger among people without skin lesions (beta = 0.18, p = 0.04), indicating that increased methylation capability may be protective against As-induced respiratory damage. In a subsample of study participants undergoing spirometric measures (n = 31), we observed inverse associations between urinary As and predictive FEV(1) (forced expiratory volume measured in 1 sec) (r = -0.37; FEV(1)/forced vital capacity ratio and primary methylation index (r = -0.42, p = 0.01). CONCLUSIONS: The findings suggest that serum CC16 may be a useful biomarker of epithelial lung damage in individuals with arsenical skin lesions. Also, we observed the deleterious respiratory effects of As exposure at concentrations lower than reported in earlier studies.     

Eosinophil-related respiratory disease in aluminium workers.

We carried out a nested case-control study in an aluminium producing plant, using the results of pre-employment examination to identify workers with an increased risk of developing work-related obstructive respiratory symptoms. Cases (n=49) are those who had become unable to work because of work-related respiratory disease. They were compared with 49 matched controls. Pre-employment eosinophil count was strongly related to the occurrence of work-related obstructive respiratory disease. This finding is interesting in the light of a possible pathogenesis.     

Acute respiratory symptoms among sisal workers in Tanzania

Background Few studies have focused on respiratory health effectsamong sisal workers. Aim To report on the prevalence of acute respiratory symptomsamong sisal processors. Methods We interviewed 163 dust-exposed brushing and decorticationworkers and 31 low-exposed security workers from six sisal estatesin Tanzania using a modified symptom score questionnaire todetermine the prevalence of acute respiratory symptoms duringwork. Groups were compared using chi-square tests, Fisher'sexact tests, t-tests and logistic regression, adjusting forconfounding factors. Results After the first working day of the week, 73% of thebrushing workers reported dry cough, 66% sneezing, 65% productivecough, 63% running nose and 34% stuffy nose. Brushing workershad a significantly higher prevalence of these symptoms thandecortication workers. Brushing and decortication workers hadsignificantly more dry cough and sneezing than the control groupof security workers, when adjusting for age, smoking, past respiratorydiseases and residence. Conclusion Processors of sisal fibre have a high prevalenceof acute respiratory symptoms. More detailed studies on workand health in sisal estates are needed, including exposure studies.     

Mortality experience of haematite mine workers in China

The mortality risk of iron ore (haematite) miners between 1970 and 1982 was investigated in a retrospective cohort study of workers from two mines, Longyan and Taochong, in China. The cohort was limited to men and consisted of 5406 underground miners and 1038 unexposed surface workers. Among the 490 underground miners who died, 205 (42%) died of silicosis and silicotuberculosis and 98 (20%) of cancer, including 29 cases (5.9%) of lung cancer. The study found an excess risk of non-malignant respiratory disease and of lung cancer among haematite miners. The standardised mortality ratio for lung cancer compared with nationwide male population rates was significantly raised (SMR = 3.7), especially for those miners who were first employed underground before mechanical ventilation and wet drilling were introduced (SMR = 4.8); with jobs involving heavy exposure to dust, radon, and radon daughters (SMR = 4.2); with a history of silicosis (SMR = 5.3); and with silicotuberculosis (SMR = 6.6). No excess risk of lung cancer was observed in unexposed workers (SMR = 1.2). Among current smokers, the risk of lung cancer increased with the level of exposure to dust. The mortality from all cancer, stomach, liver, and oesophageal cancer was not raised among underground miners. An excess risk of lung cancer among underground mine workers which could not be attributed solely to tobacco use was associated with working conditions underground, especially with exposure to dust and radon gas and with the presence of non-malignant respiratory disease. Because of an overlap of exposures to dust and radon daughters, the independent effects of these factors could not be evaluated.     

Incongruence between self-reported symptoms and objective evidence of respiratory disease among construction workers

In clinical settings, self-reported symptoms and objective evidence of disease may be poorly correlated. In the present study, symptoms and objective evidence of pulmonary disease were compared in a community sample of construction workers with occupational exposure to asbestos. Symptoms of dyspnea and cough were assessed by a standardized questionnaire. The clinical examination included a chest X-ray, pulmonary function testing (PFT), and a physical examination. Both symptoms and objective clinical findings were strongly related to years in these trades. However, less than 1% of workers reported symptoms in the absence of any clinical evidence of disease. A similar low percentage of workers denied any symptoms yet produced clear evidence of pulmonary disease on clinical examination. Results were interpreted in terms of the variety of factors which have been associated with patients' readiness, and conversely, reluctance to report symptoms. The comparatively low frequency of incongruence between symptoms and objective clinical findings in this study suggests over emphasis of malingering by other authors. Health care might be improved if more attention is given by clinicians and researchers to patients who fail to report symptoms in the presence of disease.     

Mortality experience of haematite mine workers in China.

The mortality risk of iron ore (haematite) miners between 1970 and 1982 was investigated in a retrospective cohort study of workers from two mines, Longyan and Taochong, in China. The cohort was limited to men and consisted of 5406 underground miners and 1038 unexposed surface workers. Among the 490 underground miners who died, 205 (42%) died of silicosis and silicotuberculosis and 98 (20%) of cancer, including 29 cases (5.9%) of lung cancer. The study found an excess risk of non-malignant respiratory disease and of lung cancer among haematite miners. The standardised mortality ratio for lung cancer compared with nationwide male population rates was significantly raised (SMR = 3.7), especially for those miners who were first employed underground before mechanical ventilation and wet drilling were introduced (SMR = 4.8); with jobs involving heavy exposure to dust, radon, and radon daughters (SMR = 4.2); with a history of silicosis (SMR = 5.3); and with silicotuberculosis (SMR = 6.6). No excess risk of lung cancer was observed in unexposed workers (SMR = 1.2). Among current smokers, the risk of lung cancer increased with the level of exposure to dust. The mortality from all cancer, stomach, liver, and oesophageal cancer was not raised among underground miners. An excess risk of lung cancer among underground mine workers which could not be attributed solely to tobacco use was associated with working conditions underground, especially with exposure to dust and radon gas and with the presence of non-malignant respiratory disease. Because of an overlap of exposures to dust and radon daughters, the independent effects of these factors could not be evaluated.     

Estimating historical exposure to silica among mine and pottery workers in the people's Republic of China

A quantitative retrospective exposure assessment method was developed for use in a nested case-control study of lung cancer among mine and pottery workers exposed to silica dust in the People's Republic of China. Exposure assessment was carried out in 20 mines (10 tungsten, 6 iron/copper, and 4 tin) and nine pottery factories. A job title dictionary was developed and used in both the collection of historical exposure information and work histories of 1,668 (316 cases and 1,352 controls) study subjects. Several data abstraction forms were developed to collect historical and current exposure information and employees' work histories, starting in 1950. A retrospective exposure matrix was developed on the basis of facility/job title/calendar year combinations using available historical exposure information and current exposure profiles. Information on the amount of respirable, thoracic, and free silica content in total dust was used in estimating exposure to silica. Starting in 1950, 6,805 historical estimates had been carried out for 14 calendar-year periods. We estimated the average total dust concentration to be 9 mg/M³, with a range from 28 mg/M³ in earlier years to 3 mg/M³ in recent years. Several exposure indices [such as cumulative dust, average dust, cumulative respirable (<5 μ in particle size) and thoracic (<10 μ in particle size) silica dust, average respirable and thoracic silica dust, exposure-weighted duration, and the highest/longest exposure] were calculated for individuals by merging work history and historical exposure matrix for each study subject. We developed these various measures of exposure to allow investigators to compare and contrast different indices of historical exposure to silica. © 1993 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Airflow limitation among workers in a labour-intensive coal mine in Tanzania

Objectives To describe the relationship between cumulative respirable dust and quartz exposure and lung functioning among workers in a labour-intensive coal mine. Methods The study population comprised 299 men working at a coal mine in Tanzania. Lung function was assessed using a Vitalograph alpha III spirometer in accordance with American Thoracic Society recommendations. Multiple linear regression models were developed to study the relationship between forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC and the cumulative dust or quartz exposure while adjusting for age, height and ever smoking. To evaluate trends for dose response, cumulative exposure concentrations for respirable dust and quartz were ranked and categorized in quartiles and the highest decile, with the first quartile as the reference group. Logistic regression models were used to determine odds ratios for FEV₁/FVC < 0.7 and FEV₁% < 80 for categories of cumulative dust or quartz exposure. Results The prevalence of FEV₁/FVC < 0.7 among the workers was 17.3%. Workers in the development team (20.5%) had the highest prevalence of FEV₁% < 80%. The estimates of the effects of cumulative exposure on FEV₁/FVC were −0.015% per mg years m^–3 for respirable dust and –0.3% per mg years m^–3 for respirable quartz. In logistic regression models, the odds ratios for airway limitation (FEV₁/FVC < 0.7) for the workers in the highest decile of cumulative dust and quartz exposure versus the referents were 4.36 (95% confidence interval: 1.06, 17.96) and 3.49 (0.92, 13.21), respectively. The upper 10% of workers by cumulative dust and quartz exposure also had higher odds ratios for predicted FEV₁% < 80% than the reference group odds ratio: 10.38 (1.38, 78.13) and 14.18 (1.72, 116.59), respectively. The results must be interpreted with caution due to a possible healthy worker effect and selection bias. Conclusion Exposure to respirable coal mine dust was associated with airway limitation as measured by FEV₁/FVC and predicted FEV₁%.     

Endemic work-related febrile respiratory illness among construction workers

Construction workers building Denver International Airport (DIA) reported work-related respiratory and flulike symptoms of several months duration. We performed a cross-sectional interview study of 495 randomly selected DIA workers from six contractors in comparison with preplacement workers. We defined cases as workers with two work-attributed lower respiratory symptoms and one work-attributed systemic symptom. Case rates were significantly higher among DIA workers (34%) compared with those who had never worked at DIA (2%). Risk factors for illness included exposure to fireproofing (OR, 4.21; 95% CI, 1.95–9.08), work in tunnels and adjoining areas (OR, 3.07; 95% CI, 1.84–5.12), length of DIA employment (OR, 0.65; 95% CI, 0.46–0.92), and preexisting bronchitis (OR, 2.43; 95% CI, 1.17–5.05). Our industrial hygiene investigation revealed alkaline dust (pH 11) present at a worksite associated with elevated risk of illness, and we identified airborne Penicillium mold widely distributed indoors at DIA. Clinical evaluation of 26 self-identified symptomatic DIA employees, including bronchoalveolar lavage and biopsy in 10, revealed work-related asthma in three workers and histologic evidence of chronic bronehitis in four who had never smoked. We concluded that future investigations of endemic work-related febrile respiratory illness among construction workers should evaluate its association with indoor exposure to dusts from alkaline fireproofing, Penicillium mold, mycotoxins, and bacterial bioaerosols.     

Mortality from lung cancer and respiratory disease among pottery workers exposed to silica and talc

A cohort mortality study of white men employed for at least one year between 1939 and 1966 at three plants of a single United States company was conducted to evaluate the risk of lung cancer and nonmalignant respiratory disease among workers exposed to silica dust and nonfibrous (nonasbestiform) talc in the manufacture of ceramic plumbing fixtures. Follow-up of 2,055 men through January 1, 1981, indicated a substantial excess of nonmalignant respiratory disease among those with high levels of exposure to silica dust (standardized mortality ratio = 2.26). The risk of nonmalignant respiratory disease rose with the number of years exposed, was not further enhanced by talc exposure, and appeared to be appreciably lower among those exposed in more recent time periods. For lung cancer, men exposed to high levels of silica dust with no talc exposure had a nonsignificant standardized mortality ratio of 1.37. However, those exposed to nonfibrous talc in addition to high levels of silica had a significant 2.5-fold excess risk of lung cancer. Among this group, the lung cancer standardized mortality ratio rose with increasing years of talc exposure to 3.64 among those exposed for 15 or more years. Although the role of silica as a cofactor cannot be ruled out, these data suggest that nonfibrous talc exposure is associated with excess lung cancer risk.