Subradiological silicosis

Ehrlich, Rodney; Murray, Jill; Rees, D.

doi:10.1002/ajim.22909

Cited by 22 publications

(12 citation statements)

References 52 publications

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“…Exposure-response gradients showed an increased risk of tuberculosis at an early radiologic grade of silicosis [50,51]. Further, since a significant proportion of silicosis is subradiological [31,32] the finding of an increased risk of tuberculosis at early histological grades [49] suggests an even lower threshold than that revealed radiologically. This is consistent with an earlier autopsy study showing an elevated proportion of tuberculosis even with a "slight degree of silicosis not detected radiologically in life" [59].…”

Section: Overall Completeness and Applicability Of Evidencementioning

confidence: 87%

“…More general reviews of silica and disease [8,[27][28][29][30] vary in their treatment of the silica exposure/silicosis-tuberculosis association, usually with limited critical attention to some important considerations. These include the distinction between silicosis and silica exposure in the absence of silicosis, the implication of a substantial proportion of silicosis being undetectable on the chest radiograph [31,32] and the differences between studies of tuberculosis incidence and tuberculosis mortality as the outcome. Focus is typically on tuberculosis as a clinical complication of silicosis rather than on the shape and size of exposure-relationships between silica and tuberculosis that would enable thresholds to be discerned for prevention purposes.…”

Section: Introductionmentioning

confidence: 99%

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The association between silica exposure, silicosis and tuberculosis: a systematic review and meta-analysis

et al. 2021

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Background While the association between occupational inhalation of silica dust and pulmonary tuberculosis has been known for over a century, there has never been a published systematic review, particularly of experience in the current era of less severe silicosis and treatable tuberculosis. We undertook a systematic review of the evidence for the association between (1) silicosis and pulmonary tuberculosis, and (2) silica exposure and pulmonary tuberculosis controlling for silicosis, and their respective exposure-response gradients. Methods We searched PUBMED and EMBASE, and selected studies according to a priori inclusion criteria. We extracted, summarised and pooled the results of published case-control and cohort studies of silica exposure and/or silicosis and incident active tuberculosis. Study quality was assessed on the Newcastle-Ottawa Scale. Where meta-analysis was possible, effect estimates were pooled using inverse-variance weighted random-effects models. Otherwise narrative and graphic synthesis was undertaken. Confidence regarding overall effect estimates was assessed using the GRADE schema. Results Nine studies met the inclusion criteria. Meta-analysis of eight studies of silicosis and tuberculosis yielded a pooled relative risk of 4.01 (95% confidence interval (CI) 2.88, 5.58). Exposure-response gradients were strong with a low silicosis severity threshold for increased risk. Our GRADE assessment was high confidence in a strong association. Meta-analysis of five studies of silica exposure controlling for or excluding silicosis yielded a pooled relative risk of 1.92 (95% CI 1.36, 2.73). Exposure-response gradients were observable in individual studies but not finely stratified enough to infer an exposure threshold. Our GRADE assessment was low confidence in the estimated effect owing to inconsistency and use of proxies for silica exposure. Conclusions The evidence is robust for a strongly elevated risk of tuberculosis with radiological silicosis, with a low disease severity threshold. The effect estimate is more uncertain for silica exposure without radiological silicosis. Research is needed, particularly cohort studies measuring silica exposure in different settings, to characterise the effect more accurately as well as the silica exposure threshold that could be used to prevent excess tuberculosis risk.

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Section: Overall Completeness and Applicability Of Evidencementioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

The association between silica exposure, silicosis and tuberculosis: a systematic review and meta-analysis

et al. 2021

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“…Early diagnosis followed by an immediate withdrawal from exposure is a critical factor for better prognoses. However, there is an evident limitation in identifying and defining the early signs of the disease using imaging methods, especially with chest X‐rays 46 . To minimize such difficulties, high‐resolution computed tomography has been increasingly used in clinical practice 47 .…”

Section: Discussionmentioning

confidence: 99%

“…However, there is an evident limitation in identifying and defining the early signs of the disease using imaging methods, especially with chest X-rays. 46 To minimize such difficulties, highresolution computed tomography has been increasingly used in clinical practice. 47 Crystal craftsmen from Corinto city have gained attention in the last several years due to a concerning incidence of silicosis.…”

Section: Discussionmentioning

confidence: 99%

Inflammatory and oxidative stress biomarkers induced by silica exposure in crystal craftsmen

Carneiro

Algranti

Chérot‐Kornobis

et al. 2020

American J Industrial Med

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Background Identification of biomarkers associated with the diagnosis and prognosis of silicosis would be highly advantageous in the clinical setting. The aim of this study is to evaluate inflammatory and oxidative stress biomarkers in subjects exposed to silica. Methods A cross‐sectional study of crystal craftsmen currently (n = 34) or formerly (n = 35) exposed and a group of nonexposed subjects (n = 12) was performed. Personal respirable dust samples were collected. Plasma inflammatory mediators (bone morphogenetic protein‐ BMP2 and chemokines CXCL16, and CCL5), oxidative stress enzymes (thiobarbituric acid reactive substances [TBARs] and superoxide dismutase [SOD]), and nitrite (NO2−) were analyzed in parallel with nitric oxide in exhaled breath (FeNO). Results Being currently or formerly exposed to silica was related to increased levels of CXCL16 and TBARs. Currently, exposed subjects showed decreased levels of SOD. Thirty‐seven craftsmen with silicosis (26 formerly and 11 currently exposed) showed higher levels of CXCL16, which was positively associated with the radiological severity of silicosis. Compared with the nonexposed, subjects with silicosis had higher levels of TBARs and those with complicated silicosis had lower levels of SOD. In multivariate analysis, higher levels of CXCL16 were associated with exposure status and radiological severity of silicosis. Smoking was not a confounder. FeNO did not distinguish between the exposure status and the presence of silicosis. Conclusion CXCL16 emerged as a potential biomarker that could distinguish both silica exposure and silicosis. TBARs were elevated in exposed individuals. However, their clinical applications demand further investigation in follow‐up studies of representative samples.

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“…Knowledge of the silicosis experience of the large population of black ex-miners, most of who are migrants from rural areas of Southern Africa, is limited [8,9,12,41]. Factors affecting the progression, radiological incidence and prevalence of silicosis in ex-miners include high initial mortality rates [42] and the poorly understood effects of latency from retained dust load and sub-radiological silicosis [43], both of which may result in the first appearance of radiological appearance after exposure has ended. In studies of former miners, much higher prevalences of silicosis with relatively short duration of employment have been found [8,9].…”

Section: Limitationsmentioning

confidence: 99%

Predictors of silicosis and variation in prevalence across mines among employed gold miners in South Africa

et al. 2020

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Background: The stated intention to eliminate silicosis from the South African goldmining industry as well as current programmes to find and compensate ex-miners with silicosis require an understanding of variation in silicosis prevalence across the industry. We aimed to identify the predictors of radiological silicosis in a large sample of working miners across gold mines in South Africa. Methods: Routine surveillance chest radiographs were collected from 15 goldmine "clusters" in a baseline survey undertaken in preparation for a separate tuberculosis isoniazid prophylaxis trial. All images were read for silicosis by a health professional experienced in using the International Labour Organisation (ILO) classification. Profusion thresholds of > 1/0 and > 1/1 were used. Demographic and occupational information was obtained by questionnaire. Predictors of silicosis were examined in a multivariable logistic regression model, including age, gender, racial ascription, country of origin, years since starting mine employment, mine shaft, skill category, underground work status and tuberculosis. Results: The crude silicosis prevalence at ILO > 1/1 was 3.8% [95% confidence interval (CI) 3.5-4.1%]. The range across mine shafts was 0.8-6.9%. After adjustment for covariates, the interquartile range across shafts was reduced from 2.4 to 1.2%. Black miners [adjusted odds ratio (aOR) 2.8; 95% CI 1.1-7.2] and miners in full-time underground work (aOR 2.1; 95% CI 1.3-3.4) had substantially elevated odds of silicosis, while workers from Mozambique had lower odds (aOR 0.54; 95% CI 0.38-0.77). Silicosis odds rose sharply with both age and years since starting in the industry (p for linear trend < 0.005), with 95.5% of affected miners having > 15 years since first exposure and 2.2% < 10 years. Conclusions: In surveillance of silicosis in working gold miners time since first exposure remains a powerful predictor. Age appears to be an independent predictor, while the detection of radiological silicosis in short-service miners requires attention. Public risk reporting by mines should include factors bearing on silicosis prevalence, specifically dust concentrations, with independent verification. Studies of silicosis and tuberculosis in ex-miners are needed, supported by an accessible electronic database of the relevant medical and dust exposure records of all gold miners.

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Subradiological silicosis

Cited by 22 publications

References 52 publications

The association between silica exposure, silicosis and tuberculosis: a systematic review and meta-analysis

The association between silica exposure, silicosis and tuberculosis: a systematic review and meta-analysis

Inflammatory and oxidative stress biomarkers induced by silica exposure in crystal craftsmen

Predictors of silicosis and variation in prevalence across mines among employed gold miners in South Africa

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