Outbreak of silicosis in Spanish quartz conglomerate workers

Objectives:

To describe the epidemiological and clinical characteristics of an outbreak of occupational silicosis and the associated working conditions.

Methods:

Cases were defined as men working in the stone cutting, shaping, and finishing industry in the province of Cádiz, diagnosed with silicosis between July 2009 and May 2012, and were identified and diagnosed by the department of pulmonology of the University Hospital of Puerto Real (Cádiz). A census of workplaces using quartz conglomerates was carried out to determine total numbers of potentially exposed workers. A patient telephone survey on occupational exposures and a review of medical records for all participants were conducted.

Results:

Silicosis was diagnosed in 46 men with a median age of 33 years and a median of 11 years working in the manufacturing of countertops. Of these cases, 91.3% were diagnosed with simple chronic silicosis, with an abnormal high-resolution computerized tomography (HRCT) scan. One patient died during the study period. Employer non-compliance in prevention and control measures was frequently reported, as were environmental and individual protection failures.

Conclusions:

The use of new construction materials such as quartz conglomerates has increased silicosis incidence due to intensive occupational exposures, in the context of high demand fuelled by the housing boom. This widespread exposure poses a risk if appropriate preventive measures are not undertaken.     

Quartz exposures and severe silicosis: a role for the hilar nodes

BACKGROUND: Two stonemasons working together in an environment with high concentrations of quartz pursued very different clinical courses; one died of rapidly progressive silicosis and the other developed hilar adenopathy and, later, early massive fibrosis. The exposures to quartz of these two men were investigated to allow comment on the pathogenesis of severe silicosis relative to concentrations of dust. METHODS: Estimates of exposure were based on previously taken personal dust samples, detailed lifetime occupational histories, and semiquantitative exposure modelling. RESULTS: One of the men who died had a 30 year exposure estimated to have averaged < 0.1 mg/m3, leading to hilar node fibrosis and calcification, followed by a five year exposure to about 2 mg/m3 which proved fatal. Estimates of exposure tallied with postmortem measurement of lung burden, suggesting retention of all dust deposited in the lungs over his final period of work. The younger man, working from the start of his apprenticeship alongside the older one, had a six year exposure to about 1.5 mg/m3, which caused hilar node enlargement and subsequent calcification but minimal lung involvement. CONCLUSIONS: Exposures to relatively low concentrations of quartz may be capable of causing hilar node fibrosis, impairing the clearance of any quartz inhaled subsequently. The findings support the concept that destruction of the hilar nodes by silicotic fibrosis, impairing lung clearance, has an important pathogenic role in the development of massive fibrosis, and in men subsequently exposed to very high concentrations of respirable quartz, rapidly progressive silicosis.

 

     

Silicosis in finishing workers in quartz conglomerates processing

Introduction:Outbreaks of silicosis have bene recently reported in artificial stone workers.Aim:To describe the features of silicosis in quartz conglomerate workers in North-Eastern Italy.Methods:Active search of pneumoconiosis was performed in 11 companies of North-Eastern Italy involved in the fabrication of quartz conglomerate countertops. Occupational history, lung function tests, chest X-ray and high resolution computed tomography (HRCT) were performed. In selected cases, trans-bronchial biopsies were taken for histological evaluation and identification of silica crystals in the tissue. Cumulative exposure to crystalline silica was estimated.Results:We recruited 45 workers and 24 cases of silicosis were diagnosed. Mean age at diagnosis was 43 years and duration of exposure to quartz conglomerate dust was 3.5 to 20 years. The average silica cumulative exposure was 4.3 mg/m³/y. Abnormal findings were detected in 42% of chest X-rays, in 33% of spirometry and 50% of carbon monoxide lung diffusion (DLco). HRCTs were abnormal in all cases showing well-defined rounded opacities, irregular/linear intralobular opacities and bilateral enlarged mediastinal lymph-nodes. Histological findings consistent with silicosis were observed in 24 cases. Numerous silica particles (diameter 0.1-5 μm) were identified in lung tissue.Conclusions:We reported an unexpected high incidence of silicosis in Italian workers exposed to quartz conglomerate dust. The results suggest that chest HRCT is indicated for screening of workers with high exposure to silica and DLco should be added to spirometry in health surveillance. More rigorous application of safety regulations and more effective preventive interventions at work are necessary.Key words: Silica dust, pneumoconiosis, quartz conglomerates, occupational exposure, artificial stones     

Quantitative relations between exposure to respirable quartz and risk of silicosis

Aims: To reanalyse exposure-response data from a Scottish colliery to gain a more detailed knowledge of the relations between exposure to quartz and risks of silicosis in coal miners, and hence inform the debate on an appropriate occupational standard for respirable quartz.

Methods: Detailed data on working times at different quartz concentrations were combined to produce exposure profiles for miners who had provided a full chest radiograph at a follow up survey. Logistic regression methods were used to model profusion of radiographic abnormalities category 2/1+, and a general exposure index was used to compare different quartz exposure measures in these models.

Results: Results in 371 men aged 50–74 indicated that cumulative quartz exposure at higher concentrations resulted in proportionally greater risks of abnormalities. One g.h.m^-3 of cumulative exposure at quartz concentrations greater than 2 mg.m^-3 was estimated to have equivalent risks to 3 g.h.m^-3 at lower concentrations. The timing of exposure relative to follow up appeared less important, although the study had limited power to compare different lag periods between exposure and effect.

Conclusions: Quantification of the risks of silicosis should take account of variations in quartz exposure intensity, particularly for exposure to concentrations of greater than 1 or 2 mg.m^-3, even if exposure is for relatively short periods. The risks of silicosis over a working lifetime can rise dramatically with even brief exposure to such high quartz concentrations. Risk estimates are given, to inform choice of control limits.

     

Acute Silicosis in Teflon-coated Pan Manufacturing Due to Metal Sandblasting

Abstract

Sandblasting is one of the occupational causes of silicosis. This report details three cases diagnosed as silicosis caused by sandblasting in Teflon-coated pan manufacturing: Case 1—A 24-year-old man admitted with dyspnea and cough; Case 2—An 18-year-old man admitted with shortness of breath and fever; and Case 3—A 25-year-old man admitted with dyspnea and weight loss. Chest examinations of the first and second cases revealed crackles in both lungs, but the third case was normal, no crackles. Chest x-rays showed bilateral reticulonodular densities and hilar enlargement in all cases. They were clinically and radiologically diagnosed as silicosis due to occupational exposure. All cases had worked in the sandblasting unit at a Teflon-coated pan manufacturing factory for one to three years. Silicosis is a preventable occupational lung disease, but no effective treatment is available for the disease yet. Improving workplace conditions is the most effective way to prevent silicosis.     

Risks of silicosis in coalworkers exposed to unusual concentrations of respirable quartz

OBJECTIVES: To describe the radiographic changes in coalworkers exposed to unusual concentrations of respirable quartz during the 1970s, and to relate these to exposure measurements. METHODS: Men who had worked at one Scottish colliery during the 1970s were invited to a health survey. Chest radiographs were taken from 547 subjects. Classifications of these films under the International Labour Organisation (ILO) 1980 scheme were related, by logistic regression, to existing data on individual men's exposures to respirable dust and quartz. RESULTS: Taking the median of the three readers' results on profusion of small opacities, 203 men (38%) showed progression of at least one profusion category on the 12 point scale, from the various 1970s surveys to the follow up in 1990-1. A total of 158 men (29%) had a profusion of at least 1/0, and 47 (8.6%) of at least 2/1 at the follow up survey. Large opacities were recorded as present by at least two readers for 14 (2.6%) of the men. Profusion of small opacities was strongly related to exposures experienced in the 1970s, and more strongly for quartz than for the non-quartz fraction of the dust. Estimates of risk are presented over the range of quartz exposures experienced. CONCLUSIONS: The quartz exposures experienced by some men at this colliery have caused considerable progression of radiographic abnormalities since exposure ended. The data accumulated offer opportunities for further more detailed analyses to inform debate on occupational limits for quartz exposures, both in collieries and in other industries where there is exposure to quartz in mixed dust.

 

     

Silicosis prevalence and exposure-response relations in South African goldminers

Aims: To measure the prevalence of silicosis among black migrant contract workers on a South African goldmine and to investigate exposure-response relations with silica dust.

Methods: In a cross sectional study, 520 black goldminers (aged >37 years) were interviewed and had chest radiographs taken. Silicosis was defined as International Labour Organisation Classification radiological profusion of 1/1 or greater.

Results: Mean length of service was 21.8 years (range 6.3–34.5). The mean intensity of respirable dust exposure was 0.37 mg/m³ (range 0–0.70) and of quartz 0.053 mg/m³ (range 0–0.095). The prevalence of silicosis was 18.3–19.9% depending on reader. Significant trends were found between the prevalence of silicosis and length of service, mean intensity of exposure, and cumulative exposure.

Conclusion: Results confirm a large burden of silicosis among older black workers in the South African goldmining industry, which is likely to worsen as such miners spend longer periods in continuous employment in dusty jobs. An urgent need for improved dust control in the industry is indicated. If the assumption of stability of average dust concentrations on this mine over the working life of this group of workers is correct, these workers developed silicosis while exposed to a quartz concentration below the recommended occupational exposure limit (OEL) of 0.1 mg/m³. This accords with a mounting body of evidence that an OEL of 0.1 mg/m³ is not protective against silicosis.

     

Respiratory Health and Silica Exposure of Stone Carvers in Thailand

Abstract

A cross-sectional study of dust exposures and health outcomes was conducted in a stone-carving company in Thailand. 147 respirable dust samples were collected and 97 subjects participated. Exposure indices were constructed and health outcomes, including respiratory symptoms, pulmonary functions, and chest radiographs, were assessed. Severities of employees' current exposures to quartz were 0.5–8.8 times the ACGIH-TLV,depending on job and site. Durations of exposures ranged from 4 months to 30 years. The prevalence of silicosis (profusion grade ≥ 1/0) was 2%. Pulmonary tuberculosis was also detected in 4%. Linear regression analyses revealed decreased lung function in workers with longer work durations (p < 0.05), regardless of age, sex, height, and smoking status. No clear association was seen between cumulative exposure metrics and indicators of silicosis. Elevated silica exposure levels indicate an ongoing risk of silicosis in this industry. Exposures were increased by the use of grinding tools with no ventilation and by proximity to other workers. However, because the number of workers with dust-exposure histories was limited, exposure measurements were confined to current conditions.     

SILICOSIS FROM QUARRYING AND WORKING OF GRANITE

Previous knowledge of silicosis in the Swedish granite industry suggested that the disease was neither common nor severe. In recent years, however, changes in working methods have involved a considerably increased formation of dust, and it was considered likely that the risk of contracting silicosis was increased. Reports from other countries supported this conjecture.

The 34 known cases of silicosis caused by quarrying and working of granite in Sweden were therefore reviewed. The mean duration of exposure to siliceous dust when stage I silicosis was diagnosed was 32 years, and the mean age at diagnosis was 55 years. Despite the relatively long `prediagnosis' exposure to dust, the disease showed a pronounced tendency to progression, and six cases were complicated by pulmonary tuberculosis. Eighty per cent of the men were awarded disablement benefit because of their pulmonary lesions, and four men died from silicosis alone or in combination with tuberculosis.

In Swedish granite works there is room for considerable improvement in dust suppression. Careful checks of such preventive measures and periodic medical examination of exposed persons are strongly advocated.

     

Occupational exposures and lung cancer in New Caledonia

Aims: To study the associations between occupational exposures and the risk of lung cancer in New Caledonia.

Methods: All cases diagnosed between January 1993 and December 1995 (228 lung cancers) and 305 population controls were included. Detailed information on lifetime job history, smoking, and other potential risk factors was collected by interview. Occupational exposures were assessed from the questionnaires by an industrial hygienist, without knowledge of case-control status.

Results: No significant association was found with exposures related to nickel mining and refining, the main industrial activity in the territory. Among men, an excess risk of lung cancer was found for bus and truck drivers. Increased risks were also observed in men with the highest level of cumulative exposure to cleaning products and inorganic fertilisers. Exposure to field dust was associated with lung cancer risk in both sexes, and risk increased with cumulative exposure level. In some areas tremolite asbestos derived from local outcroppings was used as a whitewash. The association between exposure to field dust and lung cancer was limited to men and women exposed to this whitewash—that is, living in areas where the soil may contain tremolite.

Conclusion: This study shows several associations between occupational exposures and lung cancer. The findings suggest that exposure to tremolite fibres from cultivated fields may increase the risk of lung cancer in New Caledonia.

     

Radiographic abnormalities among construction workers exposed to quartz containing dust

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

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

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

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

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

     

Upper-extremity musculoskeletal disorders: how many cases can be prevented? Estimates from the COSALI cohort

Objective:This study aimed to estimate the proportion and number of incident upper-extremity musculoskeletal disorders (UEMSD) cases attributable to occupational risk factors in a working population.Methods:Between 2002−2005, occupational physicians randomly selected 3710 workers, aged 20–59, from the Pays de la Loire (PdL) region. All participants underwent a standardized clinical examination. Between 2007−2010, 1611 workers were re-examined. This study included 1246 workers who were free of six main clinically diagnosed UEMSD at baseline but were diagnosed with at least one of these UEMSD at follow-up [59% of men, mean age: 38 (standard deviation 8.6) years]. Relative risks and population-attributable fractions (PAF) were calculated using Cox multivariable models with equal follow-up time and robust variance. The total number of incident UEMSD in the PdL region was estimated after adjustment of the sample weights using 2007 census data. The estimated number of potentially avoidable UEMSD was calculated by multiplying PAF by the total number of incident UEMSD in PdL.Results:At follow-up, 139 new cases of UEMSD (11% of the study sample) were diagnosed. This represented an estimated 129 320 incident cases in the PdL in 2007. Following adjustment for personal factors, 26 381 (20.4% of all incident UEMSD) were attributable to high physical exertion, 16 682 (12.9%) to low social support, and 8535 (6.6%) to working with arms above shoulder level.Conclusions:A large number and important proportion of incident UEMSD may be preventable by reducing work exposures to physical exertion and working with arms above shoulder level as well as improving social support from co-workers/supervisors.     

Commentary on ‘Evaluation of take home (para-occupational) exposure to asbestos and disease: a review of the literature’, Donovan et al.

Abstract

A case-control study (8,740 cases; 83,338 controls) was done to evaluate the association between potential occupational exposure to silica and risk of tuberculosis (TB) mortality, using the National Occupational Mortality Surveillance database for 1983–1992. Potential silica exposure was based on the decedent's usual industry and occupation. Assignment of potential exposure to silica was based on the entire range of industries and occupations. Odds ratios (ORs) for mortality from respiratory TB associated with potential high and intermediate exposures to silica were 1.30 (95% CI 1.14–1.48) and 1.07 (95% CI 0.77–1.47), respectively, adjusting for silicosis, other pneumoconioses, age, gender, race, socioeconomic status, and potential exposure to active TB. The elevated OR was seen in all subgroups: male, female, white, and black. The average age at death/among respiratory TB cases with potential silica exposure was significantly younger by four years than that among cases without potential silica exposure. The findings suggest that potential occupational exposure to silica alone, in the absence of silicosis, is associated with respiratory TB mortality, with a dose-response relationship.     

Silicosis in the iron-ore mine in Kiruna,Sweden, and the future need for silicosis control

Summary From 1931 to 1977 a total of 144 cases of silicosis have been diagnosed in the iron-ore mine in Kiruna, Sweden. Drilling, loading and tapping caused all cases of silicosis. In 24% of the cases, the disease had progressed after the diagnosis. The progression of the disease after diagnosis showed no significant correlation to the length of the exposure but a dose-response relationship was present between the cumulative quartz exposure and the stage of silicosis 20 years after the diagnosis. Signs of tuberculous infection were found in 17%. There was a significant relationship between tuberculosis and progression of the silicosis. Mortality was increased in association with silicosis stage II–III and in stages with concomitant tuberculous infection. Half of the cases of silicosis had been diagnosed before 1942, and after 1960 no more cases in stages II or III were diagnosed. The mean concentration of respiratory quartz was approximately 0.8 mg/m³ in the 1950s and early 1960s and decreased progressively to below 0.05 mg/m³ in the late 1970s. The cumulative incidence rate, with respect to the decade in which the exposure began, was 0.021% in 1951–1960. With an unaltered dose-response, less than one case of silicosis per 500 workers may be expected among those who start working underground in the 1980s. Evidently silicosis is no longer a major health risk among those who start working underground in this mine today, and it is recommended that the 40-year-old regulations for the medical prevention of silicosis be revised.     

The relative importance of whole body vibration and occupational lifting as risk factors for low-back pain

Aims: To explore the impact of occupational exposure to whole body vibration (WBV) on low back pain (LBP) in the general population and to estimate the burden of LBP attributable to occupational WBV in comparison with that due to occupational lifting.

Methods: A questionnaire including sections on WBV at work, LBP, and potential risk factors was mailed to a community sample of 22 194 men and women of working age. Sources and durations of exposure to occupational WBV were ascertained for the past week and personal vibration doses (eVDV) were estimated. Analysis was confined to subjects reporting exposures in the past week as typical of their work. Associations of LBP with eVDV, driving industrial vehicles, and occupational lifting were explored by logistic regression and attributable numbers were calculated.

Results: Significant associations were found between daily lifting of weights greater than 10 kg at work and LBP, troublesome LBP (which made it difficult to put on hosiery), and sciatica (prevalence ratios 1.3 to 1.7); but the risk of these outcomes in both sexes varied little by eVDV and only weak associations were found with riding on industrial vehicles. Assuming causal associations, the numbers of cases of LBP in Britain attributable to occupational WBV were estimated to be 444 000 in men and 95 000 in women. This compared with an estimated 940 000 male cases and 370 000 female cases of LBP from occupational lifting.

Conclusions: The burden of LBP in Britain from occupational exposure to WBV is smaller than that attributable to lifting at work.

     

Diagnosis of Severe Silicosis in Young Adults Working in Stone Polishing and Mining in Minas Gerais,Brazil

Abstract

This study describes the occurrence of silicosis in a group of stone polishing and/or mining workers who began working under the age of 18, the minimum age in Brazil for working in hazardous or unhealthy conditions. The design is that of a case series with medical follow up via a surveillance program that included medical and occupational histories, chest radiography interpreted according to International Labour Organization (ILO) Classification, and spirometry. The findings call attention to the importance of the problem of silicosis, which persists in the region despite new production technologies, legal requirements, and initiatives to protect workers. Silicosis is a public health problem that must be addressed by the implementation of public policies to improve working conditions and ensure children and teenagers are kept away from hazardous work. While Brazil has started to be a part of the global effort to eliminate silicosis and the worst forms of child labor, there are still problems that must be addressed.     

Facteurs professionnels en lien avec le suicide au sein des salariés affiliés à la Mutualité sociale agricole (MSA) et en activité entre 2007 et 2013

BackgroundWork and related exposures may play a role in suicide and there has been evidence in the literature that some occupational factors may be associated with suicide. The identification of occupational risk factors of suicide mortality among employees affiliated to the French special agricultural social security scheme (MSA), an understudied population, appears important. The objective of this study was to identify the occupational factors associated with suicide mortality among French employees from the MSA working between 2007 and 2013.MethodsThe study population included all the employees affiliated to the MSA working between 1st January 2007 and 31st December 2013, i.e. 1,699,929 men and 1,201,017 women. The studied occupational factors included: economic activity, skill level, and work contract. Survival analyses (Cox models) stratified on gender were performed using age as time scale and region and year of contract as adjustment variables.ResultsAmong men, the factors associated with an elevated suicide risk were: economic activities of forestry, agriculture and related activities, and manufacture of food products and beverages (e.g. meat, wine), low-skilled level and working in the regions of Brittany, Burgundy Franche-Comté, Pays de la Loire, Normandy, Grand Est and Centre-Val-de-Loire. No association was observed among women.ConclusionThese results suggest that economic activity and low-skilled level may be associated with suicide among men affiliated to the MSA and may contribute to the implementation of prevention interventions. Further studies are needed to confirm and better understand these associations.     

The attributable annual health costs of U.S. occupational lead poisoning

Background: U.S. occupational lead standards have not changed for decades, while knowledge about lead’s health effects has grown substantially.

Objective: The objective of this analysis was twofold: to estimate the attributable annual societal costs of health damages associated with occupationally lead-exposed U.S. workers and, more broadly, to develop methods for a fuller valuation of health damages.

Methods: I combined data voluntarily reported to NIOSH on the number of highly exposed workers with published literature on the health effects of lead in adults to estimate the potential health benefits of lowering the U.S. occupational limit. I developed simple algorithms for monetizing more fully both the direct medical and indirect (productivity) damages associated with those high lead exposures.

Results: I estimated direct medical costs of $141 million (2014US$) per year for 16 categories of health endpoints, and combined direct and indirect costs of over $392 million (2014US$) per year for the 10,000 or so U.S. workers with high occupational lead exposures.

Conclusions: Reducing allowable occupational lead limits produces annual societal benefits of almost $40,000 per highly exposed worker. Given underreporting of actual exposures and the omission of important health effects, this is likely a severe underestimate.     

Silicosis in West Country Granite Workers

The granite industry in Cornwall and Devon is briefly described, especially the production of dust in dressing the stone.

In 1951, 210 granite masons were examined (about 84% of the total at that time) and 37 (17·6%) showed silicosis. These men were followed up for 10 years. No silicosis was seen in men with less than 15 years' exposure, but after this time the risk increased to 11 out of 14 in those with over 35 years' exposure. Nine deaths occurred, two of which were due to silicosis. Radiological progression was observed in 13 of the 28 survivors. It was not necessarily associated with additional exposure but was related to age. More young men progressed.

In 1961, 132 of the granite masons (about 93% of the total at that time) were re-examined and nine new cases of silicosis were found to have developed during the 10-year interval. The exposure in the 1961 cases was comparable with that of similar cases in 1951. Thus the risk has not been much reduced over this period.

Pulmonary tuberculosis occurred in eight of the 37 cases of silicosis in 1951, and between 1951 and 1961 a further five cases were diagnosed, four being from one locality. This was by far the most frequent and disabling complication. Only one case of progressive massive fibrosis was seen.

More extensive use of protective antituberculous chemotherapy is advocated, and also better dust control.