Respiratory symptoms and functional status in workers exposed to silica, asbestos, and coal mine dusts

Prolonged cough and dyspnea following a single episode of intense silica exposure

Long term exposure to silica at worksites can cause silicosis. This typically has two radiographic forms, simple silicosis and complicated or conglomerate silicosis. Patients with acute silicosis have rapid progression of disease with fulminant respiratory failure over months rather than years. The patient described in this case report had a one-time 4 to 5-h exposure to silica and sand dust at work when his mask malfunctioned. He developed cough and shortness of breath. During his initial clinic visit he had significant cough. His chest examination was clear without crackles or wheezes. His pulmonary function tests were within normal limits. His chest x-ray was clear. Both symptoms, especially the cough, persisted over the next 6+ months even after treatment with oral corticosteroids and inhaled corticosteroids and long-acting beta agonists. Consequently, this patient developed severe cough following a one-time exposure to silica particulates. Laboratory studies have demonstrated that silica exposure can cause reactive oxygen species which potentially could have activated transient receptor potential vanilloid 1 channels in the afferent sensory nerves in his bronchial epithelium. This could cause sustained cough for more than 6 months. His symptoms improved but did not resolve with corticosteroid treatment. Therefore, this case demonstrates that acute silica exposure can cause sustained airway symptoms in healthy workers.

Emerging delivery approaches for targeted pulmonary fibrosis treatment

Pulmonary fibrosis (PF) is a progressive, and life-threatening interstitial lung disease which causes scarring in the lung parenchyma and thereby affects architecture and functioning of lung. It is an irreversible damage to lung functioning which is related to epithelial cell injury, immense accumulation of immune cells and inflammatory cytokines, and irregular recruitment of extracellular matrix. The inflammatory cytokines trigger the differentiation of fibroblasts into activated fibroblasts, also known as myofibroblasts, which further increase the production and deposition of collagen at the injury sites in the lung. Despite the significant morbidity and mortality associated with PF, there is no available treatment that efficiently and effectively treats the disease by reversing their underlying pathologies. In recent years, many therapeutic regimens, for instance, rho kinase inhibitors, Smad signaling pathway inhibitors, p38, BCL-xL/ BCL-2 and JNK pathway inhibitors, have been found to be potent and effective in treating PF, in preclinical stages. However, due to non-selectivity and non-specificity, the therapeutic molecules also result in toxicity mediated severe side effects. Hence, this review demonstrates recent advances on PF pathology, mechanism and targets related to PF, development of various drug delivery systems based on small molecules, RNAs, oligonucleotides, peptides, antibodies, exosomes, and stem cells for the treatment of PF and the progress of various therapeutic treatments in clinical trials to advance PF treatment.

Anemia and Hypoxia Impact on Chronic Kidney Disease Onset and Progression: Review and Updates

Chronic kidney disease (CKD) is caused by hypoxia in the renal tissue, leading to inflammation and increased migration of pathogenic cells. Studies showed that leukocytes directly sense hypoxia and respond by initiating gene transcription, encoding the 2-integrin adhesion molecules. Moreover, other mechanisms participate in hypoxia, including anemia. CKD-associated anemia is common, which induces and worsens hypoxia, contributing to CKD progression. Anemia correction can slow CKD progression, but it should be cautiously approached. In this comprehensive review, the underlying pathophysiology mechanisms and the impact of renal tissue hypoxia and anemia in CKD onset and progression will be reviewed and discussed in detail. Searching for the latest updates in PubMed Central, Medline, PubMed database, Google Scholar, and Google search engines were conducted for original studies, including cross-sectional studies, cohort studies, clinical trials, and review articles using different keywords, phrases, and texts such as "CKD progression, anemia in CKD, CKD, anemia effect on CKD progression, anemia effect on CKD progression, and hypoxia and CKD progression". Kidney tissue hypoxia and anemia have an impact on CKD onset and progression. Hypoxia causes nephron cell death, enhancing fibrosis by increasing interstitium protein deposition, inflammatory cell activation, and apoptosis. Severe anemia correction improves life quality and may delay CKD progression. Detection and avoidance of the risk factors of hypoxia prevent recurrent acute kidney injury (AKI) and reduce the CKD rate. A better understanding of kidney hypoxia would prevent AKI and CKD and lead to new therapeutic strategies.

Overview of lunar dust toxicity risk

Lunar dust (LD), the component of lunar regolith with particle sizes less than 20 μm, covers the surface of the Moon. Due to its fineness, jagged edges, and electrostatic charge, LD adheres to and coats almost any surface it contacts. As a result, LD poses known risks to the proper functioning of electronic and mechanical equipment on the lunar surface. However, its mechanical irritancy and chemical reactivity may also pose serious health risks to humans by a number of mechanisms. While Apollo astronauts reported mild short-lived respiratory symptoms, the spectrum of health effects associated with high-dose acute exposure or chronic low-dose exposure are not yet well-understood. This paper explores known and potential human risks of exposure to LD which are thought to be important in planning upcoming lunar missions and planetary surface work.

Case Report: Exposure to Respirable Crystalline Silica and Respiratory Health Among Australian Mine Workers

Occupational exposure to respirable crystalline silica (RCS) is common in a range of industries, including mining, and has been associated with adverse health effects such as silicosis, lung cancer, and non-malignant respiratory diseases. This study used a large population database of 6,563 mine workers from Western Australia who were examined for personal exposure to RCS between 2001 and 2012. A standardized respiratory questionnaire was also administered to collect information related to their respiratory health. Logistic regression analyses were performed to ascertain the association between RCS concentrations and the prevalence of respiratory symptoms among mine workers. The estimated exposure levels of RCS (geometric mean 0.008mg/m3, GSD 4.151) declined over the study period (p < 0.001) and were below the exposure standard of 0.05 mg/m3. Miners exposed to RCS had a significantly higher prevalence of phlegm (p = 0.017) and any respiratory symptom (p = 0.013), even at concentrations within the exposure limit. Miners are susceptible to adverse respiratory health effects at low levels of RCS exposure. More stringent prevention strategies are therefore recommended to protect mine workers from RCS exposures.

Novel drug delivery systems and disease models for pulmonary fibrosis

Pulmonary fibrosis (PF) is a serious and progressive lung disease which is possibly life-threatening. It causes lung scarring and affects lung functions including epithelial cell injury, massive recruitment of immune cells and abnormal accumulation of extracellular matrix (ECM). There is currently no cure for PF. Treatment for PF is aimed at slowing the course of the disease and relieving symptoms. Pirfenidone (PFD) and nintedanib (NDNB) are currently the only two FDA-approved oral medicines to slow down the progress of idiopathic pulmonary fibrosis, a specific type of PF. Novel drug delivery systems and therapies have been developed to improve the prognosis of the disease, as well as reduce or minimize the toxicities during drug treatment. The drug delivery routes for these therapies are various including oral, intravenous, nasal, inhalant, intratracheal and transdermal; although this is dependent on specific treatment mechanisms. In addition, researchers have also expanded current animal models that could not fully restore the clinicopathology, and developed a series of in vitro models such as organoids to study the pathogenesis and treatment of PF. This review describes recent advances on pathogenesis exploration, classifies and specifies the progress of drug delivery systems by their delivery routes, as well as an overview on the in vitro and in vivo models for PF research.

Coal Workers' Pneumoconiosis and Other Mining-Related Lung Disease: New Manifestations of Illness in an Age-Old Occupation

Coal workers' pneumoconiosis (CWP) and other mining-related lung diseases are entirely preventable, yet continue to occur. While greater attention has been given to CWP and silicosis, mining exposures cause a broad spectrum of respiratory disease, including chronic bronchitis, emphysema, and pulmonary fibrosis. Physicians must obtain a detailed occupational and exposure history from miners in order to make an accurate diagnosis and determine the risk of disease progression. Mining-related lung diseases are incurable and difficult to treat. Therefore, primary prevention by limiting dust exposure and secondary prevention through chest imaging and physiologic screening should be the primary focus of disease control.

Development of a multimedia intervention to improve pneumoconiosis prevention in construction workers using RE-AIM framework

Pneumoconiosis is a common occupational lung disease among construction workers. Educational interventions targeting specific ethnic groups of construction workers are of benefit for pneumoconiosis prevention. The aim of this study was to develop a multimedia educational intervention for pneumoconiosis prevention for South Asian construction workers, and to evaluate its feasibility, acceptability and effectiveness in increasing knowledge of pneumoconiosis, modifying beliefs about pneumoconiosis, and enhancing intention to implement measures for its prevention among the workers. This evaluation was performed using the Reach-Effectiveness-Adoption-Implementation-Maintenance framework. A one-group design was adopted and intervention mapping was used to guide the process of intervention development, while the Health Belief Model guided the development of intervention content. The intervention was delivered at construction sites, ethnic minority associations and South Asian community centres. Data were collected via surveys completed at pre-intervention, post-intervention and 3 months after the intervention. A total of 1002 South Asian construction workers participated in the intervention. The participants reported a moderate-to-large increase in knowledge, perceived susceptibility, perceived severity, perceived benefits, cues to action and self-efficacy (Cohen's d: 0.37-0.89), a small reduction in perceived barriers (Cohen's d = 0.12) and a moderate improvement in attitudes and intention to practice (Cohen's d: 0.45, 0.51) at post-intervention. A follow-up survey of 121 participants found that the implementation of preventive measures appeared to increase. Overall, the findings demonstrate that the implementation of a culturally adapted multimedia educational intervention could be an effective approach to improving knowledge, self-efficacy and intention regarding pneumoconiosis prevention among South Asian construction workers.

Impact of occupational dust exposure on dermatologic symptoms among Korean workers

Occupation-related dust exposure is common, especially with increased industrialization. While occupational dust-related health issues caused by inhalation or ingestion have been well studied, only a few studies have examined the dermatologic effects of occupational dust exposure. This study aimed to investigate the association between occupational dust exposure and dermatologic symptoms in Korean workers. Among the large-scale representative data from the fifth Korean Working Conditions Survey, 45,700 workers were selected for study. Occupational dust exposure level was categorized as none, moderate, and severe, and dermatologic symptoms were assessed using a questionnaire on health problems. We analyzed the association between occupational dust exposure and dermatologic symptoms using multivariate logistic regression. Risks of skin problems and work-related skin problems were significantly associated with the level of occupational dust exposure in a dose-dependent manner (odds ratio (95% confidence interval): moderate, 1.51 (1.14-2.01); severe, 2.39 (1.74-3.29) in general skin problems; moderate, 1.72 (1.22-2.42); severe, 3.06 (2.11-4.44) in work-related skin problems). We, thus, demonstrate an association between occupational dust exposure and skin problems. As skin absorption of dust is a major route of dust exposure at the workplace, it is necessary to determine the efficacy of continuous management of occupational dust exposure.

The experience of patients and family caregivers in managing pneumoconiosis in the family context: A study protocol

AIM

This study aims to explore the illness experience and needs of patients with pneumoconiosis and the caregiving experience of their respective family caregivers.

DESIGN

This is an exploratory qualitative study.

METHODS

Participants will be recruited during the annual patient interview with purposive sampling. Those with a confirmed diagnosis of pneumoconiosis for at least 1 year will be eligible. Patients with different levels of physical dependency will be recruited. The respective family caregivers of these patients, who are ≥21 years of age, assuming the role as primary caregivers of a pneumoconiosis patient will also be invited to join. In-depth interviews will be conducted in patients' home separately for patients and their caregivers and a home environment assessment will also be undertaken. The interview data will be transcribed verbatim, managed with the software NVivo 11 and analysed with content analysis. The ethical approval has obtained, and this study is supported by a research grant from the Pneumoconiosis Compensation Fund Board of Hong Kong on 14 August 2018.

DISCUSSION

This study will advance the knowledge on how pneumoconiosis patients and their family caregivers manage the disease in the family context. The findings of this study can inform the development of a family-oriented care model to support the pneumoconiosis patients and their family caregivers to manage this condition better.

IMPACT STATEMENT

Pneumoconiosis is the most common type of occupational lung disease in the Chinese population. These patients require long-term comprehensive services and support to assist their disease self-management. However, little is known about how these patients and their family caregivers manage the disease in the family context. The current study addresses this gap by exploring patients' illness experience and their family members' caregiving experience, which is timely to inform the design of family-oriented model of care to support this clinical cohort.

CLINICAL TRIAL REGISTRATION

This study has been registered at ClinicalTrials.gov (NCT04022902).

Occupational Respiratory Diseases of Miners from Two Gold Mines in Ghana

Objective: This study investigated respiratory disorders among gold miners in Ghana, a sub-Saharan African country. Material and Methods: A cross-sectional exploratory design that employed quantitative methods was conducted among 1001 male workers from the Obuasi and Tarkwa mines from December 2015 to April 2016. A total of 1001 workers, consisting of 505 and 496 underground and surface miners, respectively, were involved. The cross-sectional descriptive design was used because data was collected from participants of different experiences by selected participants at a time. Results: The study found significant association between age, educational background, marital status and drinking alcohol on respiratory disorders. The prevalence of asthma, pneumonia, bronchitis and emphysema were respectively 47.55%, 14.29%, 9.69% and 5.10%. Coughing was the most cited respiratory symptom (35.4%). Conclusions: The study documents important evidence on the level of respiratory disorders among miners in Ghana. Instituting appropriate health education interventions and improving the working environment is critical to improving the overall health and preventing respiratory disorders among miners.

"Bright asteroids in the polar sky"-clinic-radio-pathological correlation in an unusual case of silicotuberculosis

We present a case of acute silicosis presenting with severe breathlessness and respiratory failure. An unusual aspect in our case was the presence of acute silicosis with respiratory failure in backdrop of long-term silica exposure. The other striking aspect in this case was the demonstration of crystalline silica particles under polarizing light in bronchial lavage fluid sample and coexistence of tuberculosis with acute silicosis.

Respiratory Disability in The Van Region Based on the Medical Board Reports

OBJECTIVES

Respiratory system disorders have an impact on daily living activities of subjects, resulting in disability. Data should be gathered on disability for health services. The present study aimed to review the records of patients with a respiratory disability report from our medical board, and contribute to the national and regional statistics on disability.

MATERIAL AND METHODS

We retrospectively reviewed sociodemographic characteristics, respiratory diseases and disability rates of the patients who were examined by the Chest Diseases Department during the Medical Board evaluations in our hospital between January 1st and July 1st, 2014.

RESULTS

Among 4285 patients whose applications were submitted to the medical board for evaluation, 401 (9.3%) had a respiratory disease. Of these patients, 163 were male, and 238 were female, with a mean age of 64.2 years. The most common diseases associated with disability were chronic obstructive pulmonary disease, asthma and sequelae tuberculosis. The disability rating for respiratory system was 80% in 24.9% of patients, 40% in 34.7% of patients, and 20% in 40.4% of patients. Patients with a respiratory disability report were also considered disabled by the departments of Physical Therapy and Rehabilitation, Cardiology and Eye diseases. There was a positive correlation between disability rating and age, and a negative correlation between forced expiratory volume in first second (FEV1) and oxigen saturation measured by pulse oximeter (SpO2) values (p= 0.002; p< 0.001; p< 0.001, respectively). Furthermore, smokers had a higher disability rating compared to non-smokers (p= 0.02).

CONCLUSION

In Turkey, we have limited number of studies about respiratory disability. We believe that the present study will help determination of the etiology of respiratory disability and contribute to any action on prevention of these disorders in our region.

Hypoxia: The Force that Drives Chronic Kidney Disease

In the United States the prevalence of end-stage renal disease (ESRD) reached epidemic proportions in 2012 with over 600,000 patients being treated. The rates of ESRD among the elderly are disproportionally high. Consequently, as life expectancy increases and the baby-boom generation reaches retirement age, the already heavy burden imposed by ESRD on the US health care system is set to increase dramatically. ESRD represents the terminal stage of chronic kidney disease (CKD). A large body of evidence indicating that CKD is driven by renal tissue hypoxia has led to the development of therapeutic strategies that increase kidney oxygenation and the contention that chronic hypoxia is the final common pathway to end-stage renal failure. Numerous studies have demonstrated that one of the most potent means by which hypoxic conditions within the kidney produce CKD is by inducing a sustained inflammatory attack by infiltrating leukocytes. Indispensable to this attack is the acquisition by leukocytes of an adhesive phenotype. It was thought that this process resulted exclusively from leukocytes responding to cytokines released from ischemic renal endothelium. However, recently it has been demonstrated that leukocytes also become activated independent of the hypoxic response of endothelial cells. It was found that this endothelium-independent mechanism involves leukocytes directly sensing hypoxia and responding by transcriptional induction of the genes that encode the β2-integrin family of adhesion molecules. This induction likely maintains the long-term inflammation by which hypoxia drives the pathogenesis of CKD. Consequently, targeting these transcriptional mechanisms would appear to represent a promising new therapeutic strategy.

Selenium and exposure to fibrogenic mineral dust: a mini-review

Individuals exposed to fibrogenic mineral dust may exhibit an impaired antioxidant system and produce high levels of reactive oxygen and nitrogen species through immune cells, contributing to the perturbation of immune cell function, inflammation, fibrosis and lung cancer. The lung diseases which are caused by inhalation of fibrogenic mineral dust, known as pneumoconioses, develop progressively and irreversibly over decades. At the moment there is no known cure. The trace element selenium has potent antioxidant and anti-inflammatory properties mediated mainly through selenoproteins. Research has demonstrated that selenium has the ability to protect against cardiovascular diseases; to kill cancer cells in vitro and reduce cancer incidence; and to immunomodulate various cellular signaling pathways. For these reasons, selenium has been proposed as a promising therapeutic agent in oxidative stress associated pathology that in theory would be beneficial for the prevention or treatment of pneumoconioses such as silicosis, asbestosis, and coal worker's pneumoconiosis. However, studies regarding selenium and occupational lung diseases are rare. The purpose of this study is to conduct a mini-review regarding the relationship between selenium and exposure to fibrogenic mineral dust with emphasis on epidemiological studies. We carried out a systematic literature search of English published studies on selenium and exposure to fibrogenic mineral dust. We found four epidemiological studies. Reviewed studies show that selenium is lower in individuals exposed to fibrogenic mineral dust. However, three out of the four reviewed studies could not confirm cause-and-effect relationships between low selenium status and exposure to fibrogenic mineral dust. This mini-review underscores the need for large follow-up and mechanistic studies for selenium to further elucidate its therapeutic effects.

Pneumoconiosis in dental technicians: HRCT and pulmonary function findings

BACKGROUND

Pneumoconiosis is a form of diffuse interstitial lung disease, often resulting from occupational exposures. As dental prosthetic technicians (DPTs) build prostheses, they are exposed to many chemical materials that increase their risk of developing pneumoconiosis.

AIMS

To document pulmonary function and prevalence of pneumoconiosis in DPTs.

METHODS

A cross-sectional study of DPTs working in prosthetic laboratories who underwent pulmonary function test and high-resolution chest computed tomography (HRCT) scanning.

RESULTS

There were 76 participants and pneumoconiosis was diagnosed in 46%. The most commonly seen radiological finding was round opacities, present in 38%. Agreement among HRCT readers was moderate to good. As defined by HRCT, emphysema was diagnosed more often in those with a longer occupational history or a history of smoking, and low carbon monoxide diffusion capacity (DLCO), but not in those with pneumoconiosis. Forced expiratory rate and DLCO were significantly lower in those who had worked 16 years or more (all P < 0.05). DLCO values were significantly lower in technicians with emphysema and in current smokers (all P < 0.01). Round opacities were also present in a substantial proportion of DPTs who had 15 years or less exposure. Because HRCT is able to detect radiological changes of occupational lung disease very early, the prevalence of pneumoconiosis in our participants was quite high.

CONCLUSIONS

Pneumoconiosis identified by HRCT was present in almost half of DPTs surveyed. Appropriate education and workplace protection should be given to DPTs in order to prevent exposure to hazardous materials in dental prosthetics laboratories.

Respiratory disease related mortality and morbidity on an island of Greece exposed to perlite and bentonite mining dust

A morbidity and mortality study took place, focused on Milos Island, where perlite and bentonite mining sites are located. Official data concerning number and cause of deaths, regarding specific respiratory diseases and the total of respiratory diseases, for both Milos Island and the Cyclades Prefecture were used. Standardized Mortality Ratios (SMRs) were computed, adjusted specifically for age, gender and calendar year. Tests of linear trend were performed. By means of a predefined questionnaire, the morbidity rates of specific respiratory diseases in Milos, were compared to those of the municipality of Oinofita, an industrial region. Chi-square analysis was used and the confounding factors of age, gender and smoking were taken into account, by estimating binary logistic regression models. The SMRs for Pneumonia and Chronic Obstructive Pulmonary Disease (COPD) were found elevated for both genders, although they did not reach statistical significance. For the total of respiratory diseases, a statistically significant SMR was identified regarding the decade 1989–1998. The morbidity study revealed elevated and statistically significant Odds Ratios (ORs), associated with allergic rhinitis, pneumonia, COPD and bronchiectasis. An elevated OR was also identified for asthma. After controlling for age, gender and smoking, the ORs were statistically significant and towards the same direction.

Past dust and GAS/FUME exposure and COPD in Chinese: the Guangzhou Biobank Cohort Study

The impact of occupational dust and gas/fume exposure on chronic obstructive pulmonary disease (COPD) in developing countries has not been quantified. We examined the relationship between past dust and fume exposure and prevalence of COPD and respiratory symptoms in a cross-sectional analysis of a large Chinese population sample. Participants in the Guangzhou Biobank Cohort Study (n = 8216; 27.3% men, mean age 61.9 ± 6.8 years) had spirometry and a structured interview including exposures, symptoms, and lifestyle. Self-reported intensity and duration of dust and gas/fume exposure was used to derive cumulative exposure. COPD was diagnosed from spirometry using lower limit of normal based on prediction equations. COPD was associated with high exposure to dust or gas/fume (exposed: 87/1206 v non-exposed: 191/3853; adjusted odds ratio: 1.41; 95% confidence interval (CI) 1.06, 1.87) with no evidence of effect modification by smoking. Respiratory symptoms were associated with exposures to dust and gas/fume, with adjusted odds ratios for chronic cough/phlegm of 1.57 (1.13, 2.17) and 1.39 (1.20, 1.60) for dyspnoea. The overall population attributable fraction for COPD due to occupational exposure was 10.4% (95% CI -0.9%, 19.5%). Occupational dust and gas/fume exposure is associated with an increased prevalence of COPD in this Chinese sample, independent of smoking. The population attributable fraction in Chinese is similar to that in Western populations.

Cavitated conglomerate mass in silicosis indicating associated tuberculosis

Silicosis is the most common occupational lung disease worldwide. It leads to respiratory impairment and may have associated infections that decrease pulmonary function. We describe the case of a 55-year-old man with chronic silicosis who presented with hemoptysis and a cavitated conglomerate mass. The final diagnosis was silicotuberculosis.

Chronic cough – occupational considerations

Chronic cough is a common symptom in a wide range of respiratory conditions, and may also occur as a result of upper airway or gastro-esophageal problems. Whilst chronic cough of any cause may be exacerbated by work, in some cases it has a direct occupational cause, resulting from a harmful acute or chronic workplace exposure. Such occupational conditions may only be suspected by taking a detailed occupational history, and directly asking employed patients whether their cough improves away from work. Early and accurate diagnosis, linked with tailored drug therapy, modification of workplace exposures, and expert compensation advice is likely to offer the best outcome for this group of patients.

Relationship between induced sputum cytology and inflammatory status with lung structural and functional abnormalities in asbestosis

BACKGROUND

Asbestosis is associated with lung cellular and immunological abnormalities. Induced sputum cytology and local and systemic markers of inflammation may be helpful to characterize disease status and progression in these patients.

METHODS

Thirty-nine ex-workers with asbestosis on high-resolution CT (HRCT) and 21 non-exposed controls were evaluated. Sputum cytology and IL-8 in serum and sputum were related to lung function impairment.

RESULTS

Subjects with asbestosis had reduced sputum cellularity but higher macrophage/neutrophil ratio and % macrophage as compared with controls. Sputum and serum IL-8 were also higher in patients with asbestosis (P < 0.05). In addition, evidence of lung architectural distorption on HRCT was associated with increased levels of serum IL-8. Interestingly, absolute macrophage number was negatively correlated with total lung capacity (r = -0.40; P = 0.04) and serum IL-8 to lung diffusing capacity (r = -0.45; P = 0.01).

CONCLUSIONS

Occupationally exposed subjects with asbestosis on HRCT have cytologic abnormalities in induced sputum and increased local and systemic pro-inflammatory status which are correlated to functional impairment.

Chronic cough due to occupational factors

Within the large variety of subtypes of chronic cough, either defined by their clinical or pathogenetic causes, occupational chronic cough may be regarded as one of the most preventable forms of the disease. Next to obstructive airway diseases such as asthma or chronic obstructive pulmonary disease, which are sometimes concomitant with chronic cough, this chronic airway disease gains importance in the field of occupational medicine since classic fiber-related occupational airway diseases will decrease in the future.

Apart from acute accidents and incidental exposures which may lead to an acute form of cough, there are numerous sources for the development of chronic cough within the workplace. Over the last years, a large number of studies has focused on occupational causes of respiratory diseases and it has emerged that chronic cough is one of the most prevalent work-related airway diseases. Best-known examples of occupations related to the development of cough are coal miners, hard-rock miners, tunnel workers, or concrete manufacturing workers.

As chronic cough is often based on a variety of non-occupational factors such as tobacco smoke, a distinct separation into either occupational or personally -evoked can be difficult. However, revealing the occupational contribution to chronic cough and to the symptom cough in general, which is the commonest cause for the consultation of a physician, can significantly lead to a reduction of the socioeconomic burden of the disease.

Relationship between chest X-ray findings and pulmonary function tests in dust workers

Occupational injuries are decreasing due to the improvement in occupational management in the workplace in recent years. However, pneumoconiosis and its complications remain important occupational diseases. Based on the report 'survey on classification for supervision of pneumoconiosis in Japan' performed in 1994, this study compared age, number of years at the job and pulmonary function tests among work types, and examined the characteristics of cases in which pulmonary function results were worse than expected from the chest X-ray findings. In the comparison among work types, mean age was higher and %VC was lower among workers exposed to silica or asbestos, and FEV1.0% appeared to be lower among silica-exposed workers. Multiple regression analysis showed that silica or asbestos-exposed work environments strongly affected %VC. Some cases showed dissociation between the X-ray findings and pulmonary function tests, which appeared to be caused by certain types of work environments. In this study, all the subjects had findings of pneumoconiosis in their chest X-ray. It is necessary to perform a longitudinal survey on pneumoconiosis-free subjects to clarify the precise association of lung function tests with chest X-ray.

Is Chronic Airway Obstruction From Cotton Dust Exposure Reversible?

BACKGROUND

Exposure to cotton dust is known to cause chronic airway obstruction, but there is little information on whether the obstructive impairment is reversible after the exposure stops.

METHODS

Longitudinal changes in lung function were evaluated among 429 cotton textile workers and 449 silk workers in Shanghai, China, beginning in 1981. Both active and retired workers were tested every 4 to 6 years for 15 years.

RESULTS

Overall, cotton workers had greater annual declines in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). Compared with active workers, retired cotton workers had lower annual loss of FEV1, although the retired workers had a greater loss during their active employment than the currently active workers. No such trends were detected in silk workers. Annual declines in FEV1 in retired cotton workers were smaller with increasing time since retirement. Multivariate analysis showed that retirement was a substantial contributing factor for improved FEV1 and FVC in the cotton workers, especially among those who did not smoke. Correspondingly, remission of airflow obstruction, defined as a ratio of FEV1 and FVC of less than 70%, was more common in retirees than in the active workers, and more common in nonsmokers than in smokers.

CONCLUSION

Chronic airway obstruction related to long-term exposure to cotton dust may be partially reversible after the exposure ceases, although lung function does not return to the level found in unexposed workers.

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.

Changing patterns in asbestos-induced lung disease

STUDY OBJECTIVES

To determine patterns in asbestos-induced lung diseases found in older, less exposed workers.

DESIGN

Review of a database evaluating lung function, smoking status, form of asbestos-induced lung disease, and radiograph abnormalities.

SETTING

Outpatient clinic.

PARTICIPANTS

A total of 3383 asbestos-exposed workers referred for independent medical evaluation, including control subjects who lacked asbestos-specific radiograph abnormalities (n = 243), subjects with low International Labor Organization (ILO) scores (n = 2,685), high ILO scores (n = 312), bronchogenic cancer (n = 63), and mesothelioma (n = 80). Of these, 3,327 workers have specific smoking status information and 3,312 workers have lung volume measures.

INTERVENTIONS

Chest radiographs were interpreted by a certified B-reader, and abnormalities were quantified according to the ILO scoring system. Spirometry and lung volume measurement were performed. Subjects completed a self-administered questionnaire that was reviewed at the time of examination. Control subjects were screened on two separate occasions at least 10 years apart to exclude subclinical or slowly progressive asbestos-induced lung disease.

MEASUREMENTS AND RESULTS

The mean age of the population was 65.1 +/- 9.9 years, and the latency was 41.4 +/- 10.1 years (+/- SD). Most subjects (41.8%) had normal pulmonary function. Obstruction was the most common pulmonary function abnormality (25.4%), followed by restriction (19.3%) and a mixed pattern (6.0%). Most subjects (79.4%) had low ILO scores. Benign pleural abnormalities were the only findings in 54% of subjects with low ILO score. Subjects with high ILO scores were older, smoked more, and had a longer latency than subjects with low ILO scores and control subjects. Smokers were younger, had a shorter latency, and had paradoxically greater ILO scores than nonsmokers. Subjects with bronchogenic cancer and mesothelioma had longer latencies than control subjects and subjects with benign asbestos-induced lung disease.

CONCLUSIONS

Asbestos-induced lung disease today is characterized by low ILO scores, long latencies, greater disease magnitude in smokers, and a normal or obstructive pattern of pulmonary function abnormality. Spirometric evaluation in the absence of lung volume measurements caused misclassification that resulted in overestimation of the presence of a restrictive pattern of pulmonary function.

Respiratory impairment due to asbestos exposure in brake-lining workers

There is extensive evidence that exposure to asbestos causes pulmonary parenchymal fibrosis, pleural disease, and malignant neoplasm in asbestos-exposed workers. However, few data concerning brake-lining workers are available in the literature. In this study, we aimed to assess the long-term effects of chrysotile asbestos exposure on lung function and the risk of asbestos-related diseases in brake-lining workers. Seventy-four asbestos-exposed workers who processed brake-lining products and 12 unexposed office workers were offered pulmonary function tests (spirometry and transfer factor) in 1992 and 1999. In 1999, the mean duration of asbestos exposure was 10.00+/-4.07 and 11.02+/-4.81 years (7-31 years) in nonsmoking and smoking asbestos workers, respectively. Transfer factor (T(L), CO) and transfer coefficient (K(CO)) decline were significant in the 7-year follow-up in both smoking and nonsmoking asbestos workers. However, lung function indices of the control group, whom were all current smokers; were also found to be decreased, including FEF(75), T(L), CO and K(CO). We found minimal reticular changes in 10 asbestos workers who were all current smokers, they underwent high-resolution computed tomography scans of the chest and we found that they had peribronchial thickening resulting from smoking. As a conclusion, even in the absence of radiographic asbestosis, T(L), CO and K(CO) may decrease after a mean 10-year duration of exposure to asbestos in brake-lining workers and this is more noticeable with cigarette burden.