Silicosis is a chronic lung disease caused by inhaling large amounts of crystalline silica dust, usually over many years. Silica is a substance naturally found in certain types of stone, rock, sand and clay. Working with these materials can create a very fine dust that can be easily inhaled.Workers at greatest risk are those who move or blast rock and sand  or who use silica-containing rock or sand abrasives. Coal miners are at risk of mixed silicosis and coal workers’ pneumoconiosisFactors that influence the development of silicosis include duration and intensity of exposure, form of silicon , surface characteristics  and rapidity of inhalation after the dust is fractured and becomes airborne.According to 1999, there were >3 million workers exposed to dust containing silica and another 8.5 million workers in construction and building activities who are similarly exposed to quartz in India^1,2. Silicosis is prevalent in the states of Gujarat, Rajasthan, Haryana, Uttar Pradesh, Bihar, Chhattisgarh, Jharkhand, Odisha, West Bengal and Puducherry.

The prevalence of silicosis in India ranges from 3.5% in ordnance factories to 54.6% in slate-pencil industries³. Chronic silicosis often starts asymptomatically but progresses to exertional dyspnea and eventually dyspnea at rest, with potential complications including pulmonary consolidation, hypertension, and respiratory failure. It manifests in two primary forms: acute silicosis, which rapidly leads to severe symptoms and respiratory failure, and classic silicosis, which is more common and can be classified as simple  or complicated. Radiographic findings typically show bilateral nodular opacities, with CT scans revealing specific patterns such as perilymphatic nodules and hilar lymphadenopathy in simple silicosis, and large masses with surrounding emphysema in complicated silicosis.Spirometry is the main technique for testing lung function. Findings may range between normal values and obstructive or restrictive patterns with marked decreases in FEV1 and FVC. Observational studies in large series of patients have shown that loss of lung function with reduced FVC and FEV1 is associated with the magnitude of exposure, extent of radiological lesions and history of tuberculosis^4,5. In rodent models of silicosis, the presence of silicotic nodules and collagen deposits suggests that treatment may be ineffective. Evaluating myofibroblast differentiation, inflammation, and epithelial-mesenchymal transition is crucial, but often insufficient; multiomics approaches are needed to better understand silicosis mechanisms and identify comprehensive diagnostic biomarkers⁶.In conclusion, silicosis still poses a threat to the health of many individuals worldwide. However, there is a lack of information on effective early prevention, early diagnosis, and timely drug treatment. Thus, it is important to explore additional pathological mechanisms that might be associated with silicosis and to identify novel early diagnostic and therapeutic modalities to improve the prognosis of silicosis patient’s worldwide⁷.

To study clinical and radiological features in patients working in stone crushing, mining and other stone work units with respiratory symptoms of occupational pulmonary disease, silicosis

The study is a cross-sectional descriptive investigation conducted over one year, from June 2022 to June 2023, at the Department of Respiratory Medicine, Jaipur National University, Jaipur, Rajasthan. It focuses on patients over 18 years old admitted with a history of stone dust exposure, provided they consent to participate. Exclusion criteria include individuals diagnosed with other respiratory illnesses, such as sputum AFB positive or miliary tuberculosis, as well as those with unstable cardiac conditions.

Sample size calculation

Prevalence of silicosis in India is 10% - 22%. Considering lower level of prevalence (P) to be 10% Absolute error (E) to be 10%

According to this formula of Sample size for proportion minimum 71 patients to be considered for the study which is further extended to round off 80 patients of silicosis.

Thus final sample size for the study was 80. 

Table 1: Age wise distribution of study population (N=80)

A total of 80 patients were evaluated, and all patients were male manual laborers working in stone mine units aged between 20 and 65 years and mean age were 44.39 years. Maximum (41.25%) patients were of age group 41-50 years. 

Table 2: Duration of stone dust exposure (years) in study population (N=80)

Duration of stone dust exposure ranged from 1 to 28 years (mean duration:16.68±5.81 years); however, nearly half (76.25%) of patients had between >10 years of exposure while 30 (17.5%) patients were exposed for5-10 years and 6.25 % of people developed silicosis within 5 years of exposure to silica.

Table 3: Smoking index in study population (N=80)

SI was calculated for all patients: 17 (21.52%) were mild smokers (SI <100), 41

(51.25%) moderate (SI: 101‑300), and 4(5.0%) had heavy (>300) SI. In current study, 18 (22.5%) were nonsmokers. 

Fig: Presence of symptoms in study population (N=80)

Breathlessness was the most common symptom reported by 75 (93.75%) patients, followed by cough (63.75%), chest pain (51.25.3%), expectoration (8.75%), hemoptysis (7.5%). Wheezing was the least reported symptom (5%).

The majority of the patients had more than one symptom.

Radiological observations

Table 4:opacities in chest X-ray in study population (N=80)

On chest‑Xray small opacities [size up to 10 mm; round or irregular])were seen in 46 (57.5%) patients and 34 (42.5) chest x‑rays did not have any small opacities. Large opacities were noted in 15 (18.75%) and were absent in 65 (81.25%) X‑rays.

Table 5: X-ray finding in study finding (N=80)

In the current study, diffuse pleural thickening was present in almost all of the patients 77(96.25%), where as localized pleural thickening was present in 77.5% of the patients. Many patients had both the features. Other noted features were diaphragmatic thickening (76,95%), costo‑phrenic angle blunting (73,91.25%), and calcifications (59,73.75%).

Fig:High resolution computed tomography thorax findings of silicosis patients (N=80)

In a cohort of 80 patients with silicosis, the most common radiological features on HRCT were round opacities (92.50%) and mediastinal lymphadenopathy (87.50%). Other findings included egg shell calcification (68.75%), parenchymal band opacities (61.25%), and pleural thickening (27.50%).

Table 6:  Spirometry findings of silicosis patients (N=80)3

Among 80 silicosis patients, 12.5% had normal pulmonary function, while 60% exhibited a restrictive pattern, and 22.5% showed a mixed obstructive-restrictive pattern. Obstructive patterns were present in 5% of the cohort.

Table 7: Association between FVC/FEV1 and duration of exposure in study population (N=80)

The study shows a significant decline in both FVC and FEV1 with increasing silica dust exposure duration. Patients with less than one year of exposure had the highest mean FVC (3.90 liters) and FEV1 (3.33 liters), while those with over 10 years of exposure had the lowest values (mean FVC of 2.42 liters and FEV1 of 2.08 liters), accompanied by a significantly reduced FVC/FEV1 ratio (73.38). The correlations were statistically significant, emphasizing the adverse impact of prolonged exposure on pulmonary function.

Table 8: Mean values of Fev1- and silicosis staging and its association between silicosis stages (N=80)

FEV1 values were significantly lower in patients with acute silicosis (mean 2.20 liters) compared to those in the chronic stage (mean 3.51 liters) and the accelerated stage (mean 2.67 liters), with a p-value of 0.024. This highlights a clear association between disease severity and reduced pulmonary function.

The age distribution of the study population reveals that the majority of patients (41.25%) were between 41-50 years, with a mean age of 44.39±8.9 years. This is consistent with existing literature indicating that silicosis primarily affects middle-aged individuals after prolonged exposure to silica dust⁸ (Leung et al., 2012). The mean duration of stone dust exposure was 16.68±5.81 years, and 76.25% of patients had more than 10 years of exposure, underscoring the chronic nature of silicosis and the necessity of long-term exposure for significant clinical manifestations⁹ (Pneumoconiosis Guide, 2018).

The smoking index revealed that 51.25% of patients were moderate smokers, and 22.5% were non-smokers. Smoking exacerbates respiratory diseases, including silicosis, by contributing to the inflammatory processes and accelerating the decline in lung function¹⁰ (Balmes, 2019). This high prevalence of smoking among silicosis patients highlights the compounded risk factors affecting lung health in this population.

A significant proportion of patients reported symptoms such as breathlessness (93.75%), cough (63.75%), and chest pain (51.25%). The mean duration of symptoms was 2.75±1.45 years, indicating that patients often present with advanced disease due to the insidious onset and progression of silicosis¹¹ (Hnizdo et al., 2002). The high prevalence of breathlessness suggests severe impairment of respiratory function in these patients.

Radiological findings are critical for the diagnosis and staging of silicosis. In this study, chest X-ray and high-resolution computed tomography (HRCT) scans revealed significant abnormalities. Chest X-rays showed small nodular opacities in 57.5% of patients and large opacities in 18.75%. HRCT scans further identified round opacities in 92.5% of patients and mediastinal lymphadenopathy in 87.5%, which are characteristic of silicosis⁹ (Pneumoconiosis Guide, 2018). The presence of progressive massive fibrosis in 28.75% of patients indicates severe disease progression.

Spirometry findings were indicative of significant pulmonary function impairment. The majority (60%) of patients exhibited a restrictive pattern, with a mean FVC of 2.41±0.54 and a mean FEV1 of 2.02, which is consistent with the fibrotic nature of silicosis¹² (OSHA, 2019). The association between the duration of exposure and reduced FVC and FEV1 values underscores the progressive decline in lung function with prolonged exposure to silica dust.

HRCT thorax findings were comprehensive, with round opacities being the most common feature (92.5%), followed by linear opacities (56.25%) and ground glass opacities (26.25%). The presence of emphysema in 12% of patients and bronchiectasis in 13.75% reflects the chronic obstructive pulmonary disease (COPD) features that can coexist with silicosis¹⁰ (Balmes, 2019). Notably, egg shell calcification was present in 68.75% of patients, a classic finding in silicosis that aids in distinguishing it from other pneumoconiosis.

The type of work and associated occupational exposure are critical factors in the development of silicosis. In this study, stone cutting (manual and machine) was the predominant occupation (68.75%), followed by stone crashing (10%) and construction work (17.5%). This highlights the high-risk nature of these occupations and the need for stringent workplace safety measures to reduce exposure to silica dust¹² (OSHA, 2019).

The mean values of FEV1 varied significantly across different stages of silicosis, with the accelerated stage showing a mean FEV1 of 2.67±0.16, chronic stage 3.51±0.29, and acute stage 2.20±0.32. This variation underscores the progressive decline in lung function with advancing stages of the disease¹¹(Hnizdo et al., 2002).

The p-value of 0.024 indicates a statistically significant difference in FEV1 across the stages, reinforcing the importance of early diagnosis and intervention.

In a one-year cross-sectional study at Jaipur National University, we examined the clinic-radiological profile of silicosis in 80 male stone mine workers, aged 20 to 65, with a mean age of 44.39 years. The study aimed to identify clinical and radiological features in patients with respiratory symptoms related to stone crushing and mining.

Participants' stone dust exposure ranged from 1 to 28 years, with a mean of 16.68 years. Manual stone cutting was the most common occupation. Smoking habits revealed 21.52% mild smokers, 51.25% moderate smokers, 5% heavy smokers, and 22.5% nonsmokers.

Breathlessness was the most common symptom (93.75%), followed by cough (63.75%) and chest pain (51.25%). The mean illness duration was 2.7 years. Chest X-rays showed small opacities in 57.5% and large opacities in 18.75% of patients. Diffuse pleural thickening was seen in 96.25%.

High-Resolution CT scans revealed round opacities in 92.5% and mediastinal lymphadenopathy in 87.5%. Pulmonary function tests showed significant declines in FVC and FEV1 with increased dust exposure duration, correlating with silicosis severity.

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