Association of years of occupational quartz exposure with spirometric airflow limitation in Norwegian men aged 30-46 years

Outcome-based Definition of the Lower Limit of Normal in Spirometry: A Study of 26,000 Young Adult Men

Rationale: The definition of the lower limit of normal (LLN) of spirometric variables is not well established. Objectives: To investigate the relationship between spirometric abnormalities defined with different thresholds of the LLN and clinical outcomes and to explore the possibility of using different LLN thresholds according to the pretest probability of disease. Methods: We studied the associations between prebronchodilator spirometric abnormalities (forced expiratory volume in the first second [FEV1] < LLN, forced vital capacity [FVC] < LLN, airflow obstruction, spirometric restriction) defined with different thresholds of the LLN (10th, 5th, 2.5th, 1st percentile) and multiple outcomes (prevalence of spirometric abnormalities, respiratory symptoms, all-cause and respiratory mortality) in 26,091 30- to 46-year-old men who participated in a general population survey in Norway in 1988-1990 and were followed for 26 years. Analyses were performed with both local and Global Lung Function Initiative (GLI)-2012 reference equations, stratified by pretest risk (presence or absence of respiratory symptoms), and adjusted for age, body mass index, smoking, and education. Results: In the total population, the prevalence of airflow obstruction was 11.6% with GLI-LLN10, 11.0% with Local-LLN5, 6.1% with GLI-LLN5, 7.6% with Local-LLN2.5, and 3.5% with GLI-LLN2.5. The prevalence of spirometric restriction was 5.9% with GLI-LLN10, 5.2% with Local-LLN5, and 2.8% with GLI-LLN5. Increasingly lower thresholds of the LLN were associated with increasingly higher odds of respiratory symptoms and hazard of mortality for all spirometric abnormalities with both reference equations. Spirometric abnormalities defined with Local-LLN2.5 in asymptomatic subjects were associated with lower hazard of all-cause mortality (hazard ratio [HR], 1.50; 95% confidence interval [CI], 1.15-1.95 for FEV1 < LLN) than those defined with Local-LLN5 in the general population (HR, 1.67; 95% CI, 1.50-1.87 for FEV1 < LLN) and symptomatic subjects (HR, 1.67; 95% CI, 1.46-1.91 for FEV1 < LLN). Overall, the prevalence of spirometric abnormalities and associations with outcomes obtained with Local-LLN5 were comparable to those obtained with GLI-LLN10 and those obtained with Local-LLN2.5 to GLI-LLN5. Conclusions: There is a relationship between statistically based thresholds of the LLN of spirometric variables and clinical outcomes. Different thresholds of the LLN may be used in different risk subgroups of subjects, but the choice of the threshold needs to be evaluated together with the choice of reference equations.

Reduced lung function and cause-specific mortality: A population-based study of Norwegian men followed for 26 years

BACKGROUND AND AIM

Reduced lung function is associated with increased mortality, but it is unclear how different spirometric patterns are related to specific deaths. Aim of this study was to investigate these associations in a large general population cohort.

METHODS

The study population consisted of 26,091 men aged 30-46 years from the Pneumoconiosis Survey of Western Norway conducted in 1988-1990 with follow-up on date and cause of death for 26 years. Cox proportional hazard models were used to estimate the association between baseline FEV1, FVC, obstructive (OSP) and restrictive spirometric pattern (RSP) (z-scores calculated according to GLI-2012 equations) and mortality (European 2012 shortlist classification (E-2012)), after adjustment for age, body mass index, smoking habits, and education.

RESULTS

In total, 2462 (9%) subjects died. A predominant reduction of FEV1 (and OSP) were associated with respiratory non-cancer (E-8) (HR for one unit FEV1 z-score decrease 2.29 (95% CI 1.90, 2.77) and lung cancer mortality (E-2.1.8) (1.27(1.12, 1.44)). A similar reduction of FEV1 and FVC (and RSP) were associated with diabetes (E-4.1) (FEV1 2.21(1.67, 2.92), FVC 2.41(1.75, 3.32)), cerebrovascular (E-7.3) (1.52(1.21, 1.91), 1.54(1.19, 1.98)), ischemic heart disease (E-7.1) (1.22(1.10, 1.35), 1.21(1.08, 1.36)), neurological (E-6.3) (1.56(1.21, 2.01), 1.61(1.22, 2.13)), suicide (E-17.2) (1.37(1.13, 1.65), 1.29(1.04, 1.59)) and hematological cancer mortality (E-2.1.19-21) (1.29(1.05, 1.58), (1.26(1.00, 1.58)). No association was found between reduced lung function and mortality due to accidents, alcohol abuse, digestive and genitourinary cancer.

CONCLUSIONS

Spirometric obstruction was mainly related to pulmonary mortality. Spirometric restriction was mainly related to extra-pulmonary mortality.

Pulmonary function and respiratory symptoms in workers exposed to respirable silica dust: A historical cohort study

Background

The adverse health effects of silica are still a major concern in some industries. The purpose of this study was to evaluate pulmonary function in a group of sub-radiological silicotic workers after 11 years of silica dust exposure.

Methods

The study sample consisted of 381 exposed and 254 non-exposed workers. The history of pulmonary function parameters was obtained from workers' medical records. The data were collected through interviews with employees and completing questionnaires on demographic variables, detailed occupational and medical history, and respiratory symptoms. Workers' exposure to silica dust was also determined.

Results

The mean frequency of workers’ exposure to silica dust was 6.3 times greater than its exposure limit. All pulmonary function parameters were significantly lower in the silica-exposed workers, and the difference between the two groups was still statistically significant after adjusting the potential confounding variables. FEV1 showed the greatest reduction, and FVC and FEV1 showed a significant decreasing trend. Also the prevalence of respiratory symptoms was significantly higher in smokers than in nonsmokers among silica-exposed workers.

Conclusions

Even in the absence of radiographic evidence of silicosis, exposure to high levels of silica dust is associated with reductions in pulmonary function. In the absence of radiological evidence of silicosis, progressive deterioration of FEV1 over time most likely indicates sub-radiological silicosis. The effects were associated with the severity and duration of exposure. Exposure to sub-TLV levels of silica dust may not affect pulmonary function. Smoking appears to have a synergistic effect in relatively high silica exposures.

Silicosis: An Update and Guide for Clinicians

This overview provides an update on silicosis epidemiology with review of exposures and emerging trends in acute and accelerated silicosis in the twenty-first century. The silicosis epidemics in mining, denim sandblasting, and engineering stone industries are highlighted. Clinical presentations of silicosis and silica-related conditions such as autoimmune, kidney, and mycobacterial disease, as well as lung cancer, are discussed. Important aspects of the new OSHA 2017 Silica Standard are presented. This review also includes practical guidance for clinicians to address questions that may arise when evaluating silica-exposed patients and to the public health responses needed following a diagnosis of silica-related disease.

Prevalent Health Problems among Nepalese Underground Construction Workers

BACKGROUND

Workplace is associated with exposure to various products, which can be associated with adverse health outcomes. It is true with underground construction work. This study calculated the prevalence of common health problems among Nepalese underground construction workers in comparison to heavy construction workers. This type of study is rare in the context of Nepal and other developing countries, and we hope that the findings will help to take precautions for the prevention of these conditions.

METHOD

It was a retrospective study based on the clinical record of outpatient cases and general health checkups of all Nepalese workers available at the Project clinic, Upper Tamakoshi Hydroelectric Project, Gongar, Bigu, Dolakha. We studied three hundred and ninety-eight workers. We used multipurpose analysis and conducted the Chi-square test and calculated correlations and odds ratios.

RESULTS

Two hundred and sixteen (54.3%) participants worked inside the tunnel, and 182 (43.2%) participants worked outside the tunnel. Respiratory disease, mainly upper respiratory tract infection (URTI) (23.4%), is the most common presentation among construction workers followed by injuries (16.7%). Injuries and hypertension were significantly higher in inside the tunnel workers, and acute gastroenteritis was significantly (p value <0.05) higher in outside the tunnel workers. Increasing age increased the chance of hypertension and cutaneous fungal infection among construction workers. Further studies are required for the analysis of risk factors associated with these health conditions.

CONCLUSION

Respiratory problems are the most common health problem in underground construction workers; however, injuries and hypertension were significantly higher in tunnel workers. Acute gastroenteritis was significantly higher among outside the tunnel workers. Workplace safety should be the priority of every construction site, especially focusing to prevent respiratory problems, injuries, and accidents.

Pulmonary function and high-resolution computed tomography in outdoor rock drillers exposed to crystalline silica

OBJECTIVES

Chronic obstructive pulmonary disease and silicosis are associated with exposure to crystalline silica. We determined the exposure to respirable crystalline silica and estimated exposure-response relationships between cumulative exposure and pulmonary function in outdoor rock drillers.

METHODS

136 rock drillers and 48 referents were recruited from three heavy construction companies. 98 air samples were collected by personal sampling for determination of respirable particulate matter and crystalline silica. Information about individual job tasks, type of drilling equipment and years of exposure in different job categories was obtained by interview. Cumulative exposure to crystalline silica was calculated for all workers. Pulmonary function was assessed by spirometry. A subgroup of 39 subjects with high cumulative exposure to crystalline silica underwent high-resolution computed tomography (HRCT).

RESULTS

Cumulative exposure (mean (min-max)) to crystalline silica was 0.69 mg٠years m^-3 (0.01-5.89) in the exposed group. Mean time of exposure among rock drillers was 10.7 years (1-42). Compared with referents, the rock drillers had a lower forced expiratory volume in one second/forced vital capacity ratio (79.4 vs 81.4, p<0.05) and maximal mid-expiratory flow% (85.6 vs 93.9, p<0.05). Further, by stratifying the exposed workers into three equally large groups, a dose-response relationship was demonstrated in the highest exposed group, also in never smokers, at a mean cumulative exposure of 21.7 years at 0.08 mg٠m^-3/years. Silicosis was not detected in HRCT, but other patterns of fibrosis and emphysema were seen.

CONCLUSIONS

Outdoor rock drillers exposed to crystalline silica had significantly lower pulmonary function than referents, and signs of airflow obstruction. Silicosis was not detected.

Respirable dust and silica exposure among World Trade Center cleanup workers

The cleanup effort following the destruction of the World Trade Center (WTC) was unprecedented and involved removal of 1.8 million tons of rubble over a nine-month period. Work at the site occurred 24 hr a day, 7 days a week and involved thousands of workers during the process. The Occupational Safety and Health Administration (OSHA) conducted personal and area exposure sampling during the cleanup of the site. Secondary data analysis was performed on OSHA air sampling data for respirable dust and silica from September 2001 to June 2002 at the WTC recovery site to characterize workers' exposure. Results for silica and respirable particulate were stratified by area and personal samples as well as job task for analysis. Of 1108 samples included in the analysis, 693 were personal and 415 were area. The mean result for personal silica samples was 42 μg/m³ (Range: 4.2-1800 μg/m³). Workers identified as drillers had the highest mean silica exposure (72 μg/m³; range: 5.8-800 μg/m³) followed by workers identified as dock builders (67 μg/m³; range: 5.8-670 μg/m³). The mean result for personal samples for respirable particulate was 0.44 mg/m³ (range: 0.00010-13 mg/m³). There were no discernable trends in personal respirable dust and silica concentrations with date.

Chronic obstructive pulmonary disease in Welsh slate miners

BACKGROUND

Exposure to respirable crystalline silica (RCS) causes emphysema, airflow limitation and chronic obstructive pulmonary disease (COPD). Slate miners are exposed to slate dust containing RCS but their COPD risk has not previously been studied.

AIMS

To study the cumulative effect of mining on lung function and risk of COPD in a cohort of Welsh slate miners and whether these were independent of smoking and pneumoconiosis.

METHODS

The study was based on a secondary analysis of Medical Research Council (MRC) survey data. COPD was defined as forced expiratory volume in 1 s/forced vital capacity (FEV₁/FVC) ratio <0.7. We created multivariable models to assess the association between mining and lung function after adjusting for age and smoking status. We used linear regression models for FEV₁ and FVC and logistic regression for COPD.

RESULTS

In the original MRC study, 1255 men participated (726 slate miners, 529 unexposed non-miners). COPD was significantly more common in miners (n = 213, 33%) than non-miners (n = 120, 26%), P < 0.05. There was no statistically significant difference in risk of COPD between miners and non-miners when analysis was limited to non-smokers or those without radiographic evidence of pneumoconiosis. After adjustment for smoking, slate mining was associated with a reduction in %predicted FEV₁ [β coefficient = -3.97, 95% confidence interval (CI) -6.65, -1.29] and FVC (β coefficient = -2.32, 95% CI -4.31, -0.33) and increased risk of COPD (odds ratio: 1.38, 95% CI 1.06, 1.81).

CONCLUSIONS

Slate mining may reduce lung function and increase the incidence of COPD independently of smoking and pneumoconiosis.

The effect of manual therapy on pulmonary function in healthy adults

Manual therapy is suggested as a potentially therapeutic intervention that may improve pulmonary function. However, this form of therapy is largely based on clinical observations and hypothetical models rather than mechanistic knowledge. This study examined the influence of a single session of manual therapy applied to the thoracic spine and thorax on dynamic pulmonary function over an extended time frame in healthy adults. 21 healthy individuals (14 males) aged 19-35 (mean [SD] age = 23 [3.9], BMI [SD] = 22.97 [2.41]) completed one experimental testing session consisting of five pulmonary function tests and the delivery of a manual therapy intervention. Pulmonary function was measured at baseline and 1 minute, 10 minutes, 20 minutes and 30 minutes following the intervention. Baseline mean (SD) forced vital capacity (FVC), forced expired volume in 1 second (FEV1) and maximal voluntary ventilation (MVV) were 5.55(1.23 L), 4.64(0.92 L) and 165.7(40.0L min(-1)) respectively. The mean (SD) FEV1/FVC ratio was 0.84(0.07). There were no statistically significant changes in any of the pulmonary function measures following the manual therapy intervention. Our findings do not support the use of manual therapy to provide a short-term benefit in respiratory function to healthy adults.

Prediction models and risk assessment for silicosis using a retrospective cohort study among workers exposed to silica in China

This study aims to develop a prognostic risk prediction model for the development of silicosis among workers exposed to silica dust in China. The prediction model was performed by using retrospective cohort of 3,492 workers exposed to silica in an iron ore, with 33 years of follow-up. We developed a risk score system using a linear combination of the predictors weighted by the LASSO penalized Cox regression coefficients. The model's predictive accuracy was evaluated using time-dependent ROC curves. Six predictors were selected into the final prediction model (age at entry of the cohort, mean concentration of respirable silica, net years of dust exposure, smoking, illiteracy, and no. of jobs). We classified workers into three risk groups according to the quartile (Q1, Q3) of risk score; 203 (23.28%) incident silicosis cases were derived from the high risk group (risk score ≥ 5.91), whilst only 4 (0.46%) cases were from the low risk group (risk score < 3.97). The score system was regarded as accurate given the range of AUCs (83-96%). This study developed a unique score system with a good internal validity, which provides scientific guidance to the clinicians to identify high-risk workers, thus has important cost efficient implications.

Dust is in the air: effects of occupational exposure to mineral dust on lung function in a 9-year study

BACKGROUND

Occupational mineral dust exposure is a well-known risk factor for numerous respiratory and systemic diseases. The aim of the present longitudinal study was to assess the influence of work-associated dust exposure on spirometric results. Furthermore, the impact of implementation of stricter limit values for occupational contact with quartz dust on lung function was evaluated.

METHODS

Anthropometric data (age, gender, BMI), smoking behavior, and lung function parameters (FVC, FEV1, MEF50) from 7,204 medical examinations of 3,229 female and male workers during the years 2002-2010 were examined following Austrian standards for occupational medicine and the guidelines of the European Respiratory Society. Analysis of data was performed using models of multiple linear regression.

RESULTS

Lung function decrease over time was associated with smoking habits and duration of occupational dust exposure. Specifically, occupational quartz exposure negatively influenced the annual lung function parameters (FVC, -6.68 ml; FEV1, -6.71 ml; and MEF50, -16.15 ml/s, all p < 0.001). Thus, an overadditive effect of smoking and work-related contact with quartz was found regarding decline in MEF50 (p < 0.05). Implementation of stricter occupational limit values for dust exposure resulted in a highly significant deceleration of the annual decrease in respiratory function (p = 0.001).

CONCLUSIONS

Individual smoking habits and occupational dust exposure had a negative impact on lung function. To reduce the risk of loss of respiratory capacity, smoking cessation is especially recommended to workers exposed to quartz dust. Moreover, stricter limit values could prevent chronic occupational damage to the respiratory system.

A discriminant function model as an alternative method to spirometry for COPD screening in primary care settings in China

OBJECTIVE

COPD is often underdiagnosed in a primary care setting where the spirometry is unavailable. This study was aimed to develop a simple, economical and applicable model for COPD screening in those settings.

METHODS

First we established a discriminant function model based on Bayes' Rule by stepwise discriminant analysis, using the data from 243 COPD patients and 112 non-COPD subjects from our COPD survey in urban and rural communities and local primary care settings in Guangdong Province, China. We then used this model to discriminate COPD in additional 150 subjects (50 non-COPD and 100 COPD ones) who had been recruited by the same methods as used to have established the model. All participants completed pre- and post-bronchodilator spirometry and questionnaires. COPD was diagnosed according to the Global Initiative for Chronic Obstructive Lung Disease criteria. The sensitivity and specificity of the discriminant function model was assessed.

RESULTS

THE ESTABLISHED DISCRIMINANT FUNCTION MODEL INCLUDED NINE VARIABLES: age, gender, smoking index, body mass index, occupational exposure, living environment, wheezing, cough and dyspnoea. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, accuracy and error rate of the function model to discriminate COPD were 89.00%, 82.00%, 4.94, 0.13, 86.66% and 13.34%, respectively. The accuracy and Kappa value of the function model to predict COPD stages were 70% and 0.61 (95% CI, 0.50 to 0.71).

CONCLUSIONS

This discriminant function model may be used for COPD screening in primary care settings in China as an alternative option instead of spirometry.

Effects of occupational exposures and smoking on lung function in tile factory workers

PURPOSE

The aims of this study were to investigate the relations of occupational exposures in tile industry to lung function and to evaluate potential interaction between smoking and tile dust exposure containing silica.

METHODS

A cross-sectional study of 232 workers (response rate 100%) in a tile factory and 76 office workers (response rate 73%) from four factories in Thailand was conducted in 2006-2007. Participants answered a questionnaire and performed spirometry.

RESULTS

Factory workers had lower spirometric functions than office workers, especially those with high dust exposure. There was a dose-response relation between duration of dust exposure and FEV1 and FVC, the adjusted effect of ≥ 21 years of exposure on FEV1 being -240 ml (-100 to -380) and on FVC -300 ml (-140 to -460). The adverse effect of dust on lung function was larger in current smokers suggesting synergism between smoking and tile dust exposure.

CONCLUSIONS

This study provides evidence that long-term exposure to dust in tile industry is related to lung function reduction. There was a suggestion of synergistic effect between dust exposure and smoking. Tile factories should consider measures to reduce dust exposure and arrange spirometry surveillance for workers with such exposure. Smoking cessation should be promoted to prevent harmful effects of occupational tile dust exposure.

Norwegian population surveys on respiratory health in adults: objectives, design, methods, quality controls and response rates

BACKGROUND AND AIMS

Quantifying the prevalence of asthma, chronic obstructive pulmonary disease (COPD) and restrictive pulmonary diseases in Norway is needed to document the burden of chronic respiratory inflammatory diseases on disability, health care costs and impaired quality of life. To introduce effective interventions for prevention, cure and care, there is a prerequisite to know the environmental causes. Furthermore, using relevant and precise phenotypes from community-based studies are important for detecting molecular-genetic causes for diseases.

METHODS

The Norwegian Population Survey Initiative on Respiratory Health in Adults has, for four decades, applied international standardised methods for the recording of respiratory symptoms, health status, exposure to risk factors, socio-economic factors and the use of health services. Measurements of spirometry, metacholine bronchial responsiveness, transfer factor for carbon monoxide, atopy as well as chest X-ray examinations have been used advocating the internationally accepted methods. All surveys had similar quality controls, supervision and training of the field-worker team.

RESULTS

From 1965 to 1999, random population samples, altogether including 178 690 individuals, have been invited by random sampling to seven surveys on respiratory health in the counties of Oslo (39 998 people) and Hordaland (138 692 people). The surveys were initiated in 1964, 1972, 1985, 1988, 1991 and two in 1998. The age span of those invited persons varied from 15 to 74 years at baseline. It included 43 330 women and 135 537 men. Altogether 130 075 (73%) persons participated by returning an answered questionnaire. Spirometry results are available from 41 335 persons at baseline. A biobank for DNA and blood markers has been established. Data from longitudinally clinical-epidemiological studies were available by 2007, for three surveys after 20 years, 10 years and 6-7 years, and also for parts of three other surveys, while one survey has been examined for cause-specific mortality after 30 years. The response rates of the baseline studies varied from 90% to 68% of those invited and, in general, it has declined over 35 years. The response rate of the longitudinal studies with follow-ups also declined with time after the baseline study.

CONCLUSIONS

Great challenges for future population-based studies are (i) to keep the participation rates high in community studies; (ii) to standardise the basic clinical-epidemiological methods over decades of follow-up and to systematically transfer these methods into new populations with different languages and cultures and (iii) to focus on important research questions on respiratory health for the community.

Chronic obstructive pulmonary disease and occupational exposure to silica

Prolonged exposure to high levels of silica has long been known to cause silicosis This paper evaluates the evidence for an increased risk of chronic obstructive pulmonary disease (COPD) in occupations and industries in which exposure to crystalline silica is the primary exposure, with a focus on the magnitude of risks and levels of exposure causing disabling health effects. The literature suggests consistently elevated risks of developing COPD associated with silica exposure in several occupations, including the construction industry; tunneling; cement industry; brick manufacturing; pottery and ceramic work; silica sand, granite and diatomaceous earth industries; gold mining; and iron and steel founding, with risk estimates being high in some, even after taking into account the effect of confounders like smoking. Average dust levels vary from about 0.5 mg.m3 to over 10 mg.m3 and average silica levels from 0.04 to over 5 mg.m3, often well above occupational standards. Factors influencing the variation from industry to industry in risks associated with exposure to silica-containing dusts include (a) the presence of other minerals in the dust, particularly when associated with clay minerals; (b) the size of the particles and percentage of quartz; (c) the physicochemical characteristics, such as whether the dust is freshly fractured. Longitudinal studies suggest that loss of lung function occurs with exposure to silica dust at concentrations of between 0.1 and 0.2 mg.m3, and that the effect of cumulative silica dust exposure on airflow obstruction is independent of silicosis. Nevertheless, a disabling loss of lung function in the absence of silicosis would not occur until between 30 and 40 years exposure.

Heme oxygenase-1, a potential biomarker of chronic silicosis, attenuates silica-induced lung injury

RATIONALE

Heme oxygenase-1 (HO-1), a rate-limiting enzyme in heme catabolism, has antioxidative, antiapoptotic, and antiinflammatory activities. We examined whether HO-1 might be involved in silicosis.

OBJECTIVES

To investigate whether HO-1 can reduce silicosis in mice and humans.

METHODS AND MEASUREMENTS

Silicosis was studied using a murine model, and in 46 male patients. Serum HO-1 and 8-hydroxydeoxyguanosine (a marker of oxidative stress) were measured by enzyme-linked immunosorbent assay. Levels of HO-1 were measured by immunohistochemistry and immunoblotting.

MAIN RESULTS

Serum HO-1 levels were significantly elevated in patients with silicosis compared with age-matched control subjects or patients with chronic obstructive pulmonary disease. Serum HO-1 levels also correlated inversely with serum 8-hydroxydeoxyguanosine levels and positively with vital capacity and forced expiratory volume in one second in patients with silicosis. HO-1 was present in the lungs of humans and mice with silicosis, especially at sites of silica particle deposition. In mice, silica exposure was associated with acute leukocyte infiltration, leading to development of silicotic lung lesions. The inflammation was suppressed by treatment with hemin, an inducer of HO-1, and enhanced by zinc protoporphyrin, an inhibitor of HO-1.

CONCLUSIONS

Pulmonary HO-1 expression is increased in silicosis. HO-1 suppresses reactive oxygen species activity, and subsequent pathologic changes, thereby attenuating disease progression.

Occupational interstitial lung disease

Occupational interstitial lung diseases are a diverse group of disorders of varied cause. Occupational causes account for a significant portion of all interstitial lung diseases, and new causes continue to be described. Although some are diseases of antiquity, they continue to occur in the workplace and often are misdiagnosed as "idiopathic" when physicians miss the connection to past-inhaled exposures. All of these diseases are preventable with reduction or elimination of workplace exposure. This article reviews the spectrum of diseases caused by exposure to metal dust and fumes, inorganic fibers, and nonfibrous inorganic dust. It also details an approach to the diagnosis, evaluation, and management of this group of illnesses.

Cumulative exposure to dust and gases as determinants of lung function decline in tunnel construction workers

AIMS

To study the relation between lung function decrease and cumulative exposure to dust and gases in tunnel construction workers.

METHODS

A total of 651 male construction workers (drill and blast workers, tunnel concrete workers, shotcreting operators, and tunnel boring machine workers) were followed up by spirometric measurements in 1989-2002 for an average of six years. Outdoor concrete workers, foremen, and engineers served as a low exposed referent population.

RESULTS

The between worker component of variability was considerably reduced within the job groups compared to the whole population, suggesting that the workers within job groups had similar exposure levels. The annual decrease in FEV1 in low-exposed non-smoking workers was 21 ml and 24 ml in low-exposed ever smokers. The annual decrease in FEV1 in tunnel construction workers was 20-31 ml higher than the low exposed workers depending on job group for both non-smokers and ever smokers. After adjustment for age and observation time, cumulative exposure to nitrogen dioxide showed the strongest association with a decrease in FEV1 in both non-smokers, and ever smokers.

CONCLUSION

Cumulative exposure to nitrogen dioxide appeared to be a major risk factor for lung function decreases in these tunnel construction workers, although other agents may have contributed to the observed effect. Contact with blasting fumes should be avoided, diesel exhaust emissions should be reduced, and respiratory devices should be used to protect workers against dust and nitrogen dioxide exposure.

Chronic obstructive pulmonary disease due to occupational exposure to silica dust: a review of epidemiological and pathological evidence

Occupational exposure is an important risk factor for chronic obstructive pulmonary disease (COPD), and silica dust is one of the most important occupational respiratory toxins. Epidemiological and pathological studies suggest that silica dust exposure can lead to COPD, even in the absence of radiological signs of silicosis, and that the association between cumulative silica dust exposure and airflow obstruction is independent of silicosis. Recent clinicopathological and experimental studies have contributed further towards explaining the potential mechanism through which silica can cause pathological changes that may lead to the development of COPD. In this paper we review the epidemiological and pathological evidence relevant to the development of COPD in silica dust exposed workers within the context of recent findings. The evidence surveyed suggests that chronic levels of silica dust that do not cause disabling silicosis may cause the development of chronic bronchitis, emphysema, and/or small airways disease that can lead to airflow obstruction, even in the absence of radiological silicosis.

Occupational airborne exposure and the incidence of respiratory symptoms and asthma

Several prevalence studies have suggested an association between occupational exposure and respiratory symptoms and asthma, but there has been a lack of incidence studies to verify this. This study examined the incidence of respiratory symptoms and asthma in an 11-year Norwegian community cohort study with 2,819 subjects. Predictors examined were sex, age, educational level, lifetime exposure to quartz, asbestos, and dust or fumes, as well as smoking habits and pack-years. The prevalence of exposure to quartz, asbestos, and dust or fumes was, respectively, 3.7%, 5.0%, and 28.3% at baseline. In those exposed to dust or fumes, the odds ratios (95% confidence intervals) varied between 1.4 (1.1, 1.7) and 2.1 (1.3, 3.2) for developing respiratory symptoms or asthma after adjusting for sex, age, educational level, and smoking. Between 5.7% and 19.3% of the incidence of respiratory symptoms and 14.4% of the incidence of asthma were attributable to dust or fumes exposure after adjustment for sex, age, educational level, and smoking. In conclusion, airborne occupational exposure increases the incidence of respiratory symptoms and asthma, independent of sex, age, educational level, smoking habits, and pack-years.

Expiratory and inspiratory forced vital capacity and one-second forced volume in asymptomatic never-smokers in Norway

The objectives of this study were to examine within and between individual variation detected during forced expiratory (FE) and forced inspiratory (FI) manoeuvers in a general population and to investigate the dependence of these variables on age, body size, and gender. A random sample of asymptomatic never smokers who had never been exposed occupationally to quartz or asbestos and who were living on the south-western coast of Norway were examined by spirometry; 81% of the individuals invited to attend did so. Of the 488 subjects between 18 and 73 years of age, 98% contributed three acceptable recordings for forced expiratory vital capacity (FVC) and one-second forced expiratory volume (FEV1), 94% contributed three acceptable recordings for forced inspiratory vital capacity (FIVC) and 85% contributed three acceptable recordings for one-second forced inspiratory volume (FIV(1)). The within-subject variation increased with body height and was considerably larger for FIV(1) than for FVC, FEV(1) or FIVC. A four-parameter model of pulmonary function measurement divided by height squared, including a gender term and a linear and quadratic term of age, fit the median of the observed values well. The residuals had a close-to-normal distribution, and the fifth-percentile values were estimated as the lower limit of normal. The peak value of dynamic lung volumes was observed into the middle of the fourth decade of life, and the decline thereafter did not differ greatly between the genders or among the different indices. The forced inspiratory volumes are the first reported in any reference population.

Cumulative exposure to dust causes accelerated decline in lung function in tunnel workers

OBJECTIVES

To examine whether underground construction workers exposed to tunnelling pollutants over a follow up period of 8 years have an increased risk of decline in lung function and respiratory symptoms compared with reference subjects working outside the tunnel atmosphere, and relate the findings to job groups and cumulative exposure to dust and gases.

METHODS

96 Tunnel workers and a reference group of 249 other heavy construction workers were examined in 1991 and re-examined in 1999. Exposure measurements were carried out to estimate personal cumulative exposure to total dust, respirable dust, alpha-quartz, oil mist, and nitrogen dioxide. The subjects answered a questionnaire on respiratory symptoms and smoking habits, performed spirometry, and had chest radiographs taken. Radiological signs of silicosis were evaluated (International Labour Organisation (ILO) classification). Atopy was determined by a multiple radioallergosorbent test (RAST).

RESULTS

The mean exposure to respirable dust and alpha-quartz in tunnel workers varied from 1.2-3.6 mg/m3 (respirable dust) and 0.019-0.044 mg/m3 (alpha-quartz) depending on job task performed. Decrease in forced expiratory volume in 1 second (FEV1) was associated with cumulative exposure to respirable dust (p<0.001) and alpha-quartz (p=0.02). The multiple regression model predicted that in a worker 40 years of age, the annual decrease in FEV1 would be 25 ml in a non-exposed non-smoker, 35 ml in a non-exposed smoker, and 50-63 ml in a non-smoking tunnel worker (depending on job). Compared with the reference group the odds ratio for the occurrence of new respiratory symptoms during the follow up period was increased in the tunnel workers and associated with cumulative exposure to respirable dust.

CONCLUSIONS

Cumulative exposures to respirable dust and alpha-quartz are the most important risk factors for airflow limitation in underground heavy construction workers, and cumulative exposure to respirable dust is the most important risk factor for respiratory symptoms. The finding of accelerated decline in lung function in tunnel workers suggests that better control of exposures is needed.

Smoking, respiratory symptoms, and diseases : a comparative study between northern Sweden and northern Finland: report from the FinEsS study

STUDY OBJECTIVES

The influences of different smoking categories on the prevalence of respiratory symptoms, asthma, and chronic bronchitis have been examined in the most northern province of Sweden, Norrbotten, and in Lapland, Finland. The two areas have similar geographic and demographic conditions.

METHODS AND STUDY POPULATION

The study is a part of the FinEsS studies, which are epidemiologic respiratory surveys in progress in Sweden, Finland, and Estonia. A random sample of 20- to 69-years-olds were invited to answer a postal questionnaire about respiratory symptoms, smoking habits, and occupation. In Norrbotten, 8,333 subjects were invited and 7,104 responded (85%). In Lapland, 8,005 were invited and 6,633 responded (83%).

RESULTS

The participation by age and sex was similar in both countries. The prevalence of smokers in Lapland was 32% vs 26% in Norrbotten. Significantly more women than men in Norrbotten were smokers, while the opposite was true for Lapland. Sputum production was the most prevalent symptom in both areas, 25% in Lapland vs 19% in Norrbotten. The prevalence of chronic productive cough was 11% in Lapland and 7% in Norrbotten. Bronchitic symptoms were more prevalent in Lapland among both smokers and nonsmokers. A positive family history of chronic obstructive airway disease together with increased number of consumed cigarettes showed an additive effect for both chronic productive cough and wheezing. The odds ratio (OR) for wheezing during the last 12 months was 3.8 for subjects without a family history of obstructive airway disease who consumed > 14 cigarettes per day compared with nonsmokers, but if the subjects had a family history of obstructive airway disease, the risk for wheezing increased to OR 8.4.

CONCLUSION

Bronchitic symptoms were more common in Finland. The difference remained also after correction for demographic variables including smoking habits, age and socioeconomic group, and family history of obstructive airway disease. Identical methods, sample composition, and the high participation rate contribute to the validity of the results. Air pollution, including environmental tobacco smoke, may contribute to the difference. To explain the difference, further analysis and investigations of social and environmental factors as well as genetic factors are needed.

Gas and dust exposure in underground construction is associated with signs of airway inflammation

Exposure to gases and dust may induce airway inflammation. It was hypothesized that heavy construction workers who had been exposed to dust and gases in underground construction work for 1 yr, would have early signs of upper and lower airway inflammation, as compared to outdoor workers. A study group comprising 29 nonsmoking underground concrete workers (mean +/- SD age 44+/-12 yrs), and a reference group of 26 outdoor concrete workers (39+/-12 yrs) were examined by acoustic rhinometry, nasal and exhaled nitric oxide spirometry and a questionnaire on respiratory symptoms. Exposure measurements were carried out. The underground workers had higher exposure to total and respirable dust, alpha-quartz and nitrogen dioxide than the references (p<0.001). The occurrence of respiratory symptoms was higher in the underground workers than in the references (p<0.05). Exhaled nitric oxide (NO) (geometric mean+/-SEM) was higher in the underground workers than in the references (8.4+/-1.09 versus 5.6+/-1.07 parts per billion (ppb), p = 0.001), whereas spirometric values were comparable. The underground workers had smaller nasal cross-sectional area and volume than the references, and more pronounced increases after decongestion (p<0.001). To conclude the exposure in underground construction may cause nasal mucosal swelling and increased levels of exhaled nitric oxide, indicating signs of upper and lower airway inflammation.

Increased risk of obstructive pulmonary disease in tunnel workers

BACKGROUND

Tunnel workers are exposed to gases and particles from blasting and diesel exhausts. The aim of this study was to assess the occurrence of respiratory symptoms and airflow limitation in tunnel workers and to relate these findings to years of exposure.

METHODS

Two hundred and twelve tunnel workers and a reference group of 205 other heavy construction workers participated in a cross sectional investigation. Exposure measurements were carried out to demonstrate the difference in exposure between the two occupational groups. Spirometric tests and a questionnaire on respiratory symptoms and smoking habits were applied. Atopy was determined by a multiple radioallergosorbent test (RAST). Radiological signs of silicosis were evaluated. Respiratory symptoms and lung function were studied in relation to years of exposure and adjusted for smoking habits and atopy.

RESULTS

Compared with the reference subjects the tunnel workers had a significant decrease in forced vital capacity (FVC) % predicted and forced expiratory volume in one second (FEV(1)) % predicted when related to years of exposure. Adjusted FEV(1) decreased by 17 ml for each year of tunnel work exposure compared with 0.5 ml in outdoor heavy construction workers. The tunnel workers also reported significantly higher occurrence of respiratory symptoms. The prevalence of chronic obstructive pulmonary disease (COPD) was 14% in the tunnel workers compared with 8% in the reference subjects.

CONCLUSION

Exposure to dust and gases from diesel exhaust, blasting, drilling and rock transport in tunnel work enhances the risk for accelerated decline in FEV(1), respiratory symptoms, and COPD in tunnel workers compared with other heavy construction workers.