One-year lung transplantation outcomes for engineered stone countertop workers with silicosis at a single center in Southern California, 2019 to 2023

Abstract

Background

In the past decade, growing industrial exposure to respirable crystalline silica from manufacturing engineered stone (ES) products has caused rapidly progressive, irreversible silicosis worldwide. Consequently, there has been a recent surge in lung transplants for ES silicosis but few reports of post-transplant outcomes. We compared perioperative and 1-year post-transplant outcomes for silicosis and nonsilicosis interstitial lung disease (ILD) recipients at UC San Diego (UCSD) Health.

Methods

Using the electronic health record and United Network for Organ Sharing database, we identified 7 patients with silicosis and 69 with nonsilicosis ILD who underwent double lung transplantation at UCSD from 2019-2023. We compared pretransplant, perioperative, and 1-year post-transplant outcomes between groups.

Results

Recipients with silicosis were younger than those with nonsilicosis ILD (43.1 ± 9.9 vs 59.3 ± 7.1 years; p < 0.001). All 7 patients with silicosis were male, and 6 reported Hispanic/Latino ethnicity. All silicosis patients reported employment in the countertop industry using ES products. Before transplant, patients with silicosis had significantly lower mean percent predicted (PP) forced expiratory volume in 1 second (24.3 PP vs 46.6 PP; p < 0.001) and forced vital capacity (28.7 PP vs 43.3 PP; p < 0.01) than patients with nonsilicosis ILDs. Though ischemic times were greater for silicosis recipients, perioperative complication rates were similar. At 1-year post-transplant, there were no differences in survival, allograft rejection rates, or pulmonary function tests.

Conclusions

Though reflecting a failure of prevention, lung transplantation should be considered as a therapeutic option for patients with end-stage silicosis from exposure to ES.

Background

Exposure to respirable crystalline silica (RCS) may lead to the development of silicosis, a progressive and irreversible fibrotic lung disease. Until recently, severe silicosis requiring lung transplantation typically occurred after many years of chronic and intense RCS exposure, encountered in industries such as sandblasting, mining, foundry work, and concrete and cement mixing.1, 2 Over the past decade, growing industrial exposure to RCS from manufacturing engineered stone (ES) products, frequently referred to as artificial stone or quartz, has led to markedly accelerated disease in exposed individuals.3, 4, 5, 6, 7 ES is a cost-efficient and highly customizable product that has become the most common selection for US countertop surfaces over the last 15 years.⁸ Unlike natural stone products (e.g., granite and marble) which typically contain <40% silica, ES often contains over 90% silica along with resins and pigment additives. Workers who cut, grind, shape, and polish ES products for residential or commercial purposes have developed severe silicosis in many high-income countries worldwide.5, 6, 7, 9, 10, 11, 12, 13 Several case series in the United States have described a rapidly progressive form of silicosis in ES fabrication workers, who are disproportionately younger Latino men.5, 6, 14 A substantial proportion of these workers have progressive massive fibrosis (PMF), the most severe form of silicosis.

Patients with silicosis secondary to ES exposure have worse pulmonary physiology and a more rapid decline in lung function compared to patients exposed to natural stone, even after cessation of exposure.4, 7, 15 There is no evidence-based pharmacologic treatment for silicosis, and in advanced cases, lung transplantation is often the only therapeutic option. Several studies have shown that non-ES exposed silicosis patients have noninferior survival outcomes compared to patients who receive transplants for other occupational or fibrotic lung diseases.16, 17, 18, 19, 20, 21

Apart from the published experience in Israel and China,15, 18, 22 few studies have examined lung transplant outcomes in ES workers with rapidly progressive disease. A retrospective analysis by Israeli investigators of 17 lung transplants for ES silicosis showed no significant differences in survival after 38 median months compared to 73 transplant recipients with idiopathic pulmonary fibrosis (IPF).¹⁵ Similar outcomes were found in lung transplant recipients in China comparing IPF with work-related lung disease, including 19 with ES silicosis.¹⁸

In this US single-center analysis, we compared the pretransplant demographics and clinical parameters, perioperative management, and post-transplant outcomes among stone countertop workers with silicosis compared to transplant recipients with nonsilicosis interstitial lung disease (ILD). We hypothesized that stone countertop workers with silicosis would have similar 1-year transplant outcomes compared to patients who underwent lung transplant for nonsilicosis ILD.

Materials and methods

A retrospective chart review was conducted among patients who underwent lung transplantation at the University of California San Diego (UCSD) Health from January 2019 through December 2023. Patients were classified as requiring transplant due to silicosis or nonsilicosis ILD. Pretransplant diagnoses were determined by the lung transplant pulmonologist and subsequently confirmed on explanted lung pathology. All patients transplanted for silicosis during this time were included. The nonsilicosis ILD group consisted of patients transplanted for IPF, nonspecific interstitial pneumonia, connective tissue disease-associated interstitial lung disease, and hypersensitivity pneumonitis. Transplants for other ILD etiologies were excluded due to small sample sizes (n ≤ 6). Single lung transplants and all patients transplanted for any reason other than ILD were also excluded.

Patient-level data were collected from the electronic health record and the United Network for Organ Sharing database, including demographics, occupational industry and tenure, respirator use, and pretransplant, perioperative, and 1-year post-transplant clinical parameters. Predicted lung function values were calculated based on recipient characteristics and according to standards set by the American Thoracic Society.²³ This study was exempted by the UCSD Institutional Review Board (IRB), and informed consent was waived (IRB #809928). This study adheres to the principles of the International Society for Heart and Lung Transplantation statement on Transplant Ethics.

Statistical analysis

Descriptive statistical analyses were used to determine recipient characteristics. Normal distribution of data was assessed, and Pearson’s chi-square test, Mann-Whitney U test, Student’s t-test, Kruskal-Wallis test, and 1-way analysis of variance were used to compare means and proportions of variables as appropriate. We performed adjusted logistic regression to compare the primary 1-year outcomes of survival and transplant rejection. We adjusted these analyses for age given baseline differences between groups and the expectation that post-transplant outcomes might be confounded by age at transplant. p < 0.05 was considered statistically significant. All statistical analyses were performed using Stata (version 18.5; StataCorp) and Prism (version 10; GraphPad).

Results

Baseline characteristics of recipients

From 2019-2023, 208 lung transplants were performed at UCSD, of which 76 double lung transplants were included for analysis (Figure 1). Seven (9.2%) were diagnosed with silicosis, and 69 (90.8%) were diagnosed with nonsilicosis ILD, of whom the majority (52.2%) were diagnosed with IPF (Table 1). Representative chest imaging and lung histopathology in patients with end-stage silicosis are shown in Figure 2, Figure 3, respectively.

Figure 1.

Flow diagram for inclusion and exclusion of recipients. BOOP, bronchiolitis obliterans organizing pneumonia; ILD, interstitial lung disease; NSIP, nonspecific interstitial pneumonia; PPFE, pleuroparenchymal fibroelastosis; UCSD, University of California San Diego Health; UIP, usual interstitial pneumonia.

Table 1.

Baseline Characteristics of Lung Transplant Recipients (n = 76)

Characteristic	Silicosis	Nonsilicosis ILD	Total	p
n	7 (9.2%)	69 (90.8%)	76
Age (years)	43.1 (9.9)	59.3 (7.1)	57.8 (8.7)	<0.001a
Sex
Female	0 (0.0%)	29 (42.0%)	29 (38.2%)	0.029b
Male	7 (100.0%)	40 (58.0%)	47 (61.8%)
Race/ethnicity
Hispanic/Latino	6 (85.7%)	29 (42.0%)	35 (46.1%)	0.294b
White, non-Hispanic	1 (14.3%)	34 (49.3%)	35 (46.1%)
Black, non-Hispanic	0 (0.0%)	2 (2.9%)	2 (2.6%)
Asian, non-Hispanic	0 (0.0%)	2 (2.9%)	2 (2.6%)
Native Hawaiian/other Pacific Islander, non-Hispanic	0 (0.0%)	2 (2.9%)	2 (2.6%)
Primary diagnosis
IPF	–	36 (52.2%)	–
NSIP	–	7 (10.1%)	–
CTD-ILD	–	16 (23.2%)	–
HP	–	10 (14.5%)	–
Pretransplant PFTsc
FEV1 PP	24.3 (12.3)	46.6 (15.2)	44.5 (16.3)	<0.001a
FVC PP	28.7 (12.5)	43.3 (14.0)	42.0 (14.4)	<0.01a
FEV1/FVC (%)	73.9 (22.1)	85.8 (9.0)	84.6 (11.2)	0.007a
Mean PAP (mm Hg)	27.8 (9.3)	26.4 (10.0)	26.5 (9.9)	0.576d
Missing	1 (14.3%)	0 (0.0%)	1 (1.3%)
Functional status pretransplant
10%-30% (hospitalization indicated)	5 (71.4%)	37 (53.6%)	41 (55.3%)	0.622b
40%-70% (disabled; requiring assistance)	2 (28.6%)	29 (42.0%)	31 (40.8%)
80%-90% (symptomatic, but independent)	0 (0.0%)	3 (4.3%)	3 (3.9%)
100% (normal)	0 (0.0%)	0 (0.0%)	0 (0.0%)

Abbreviations: CTD-ILD, connective tissue disease-associated interstitial lung disease; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; HP, hypersensitivity pneumonitis; ILD, interstitial lung disease; IPF, idiopathic pulmonary fibrosis; NIPPV, noninvasive positive pressure ventilation; NSIP, nonspecific interstitial pneumonia; PAP, pulmonary artery pressure; PFTs, pulmonary function tests; PP, percent predicted.

Values shown as mean (standard deviation) or frequency (percent).

^aStudent's t-test.

^bPearson's chi-square test.

^cTwo patients missing FEV1 PP and FVC PP parameters, and three patients missing FEV1/FVC parameters. All were non-silicosis ILD.

^dMann-Whitney U test.

Figure 2.

Representative high-resolution coronal computed tomography (CT) images of patients with end-stage silicosis requiring lung transplantation. Image (A) demonstrates numerous bilateral pulmonary nodules and bilateral consolidative, mass-like opacities in a predominantly dependent perihilar distribution. There is subcarinal and left paraesophageal lymphadenopathy with mass effect on the right and left mainstem airways without significant stenosis. Image (B) demonstrates extensive upper lobe predominant confluent mass-like consolidation with areas of calcification associated with volume loss. There are trace bilateral pleural effusions with pleural thickening toward the apices. Enlarged, calcified mediastinal and hilar lymph nodes are present. Image (C) demonstrates multifocal areas of patchy consolidation most severe in the right upper lobe. There are mosaic and confluent ground-glass opacities which are most severe in the lower lobes. Multiple moderately enlarged, calcified mediastinal and hilar lymph nodes are present. Image (D) demonstrates upper lobe predominant consolidation associated with traction bronchiectasis. There is perilymphatic nodularity which is slightly more prominent in the upper lobes. Bilateral hydropneumothoraces and extensive pneumomediastinum are present along with bilateral chest tubes. Calcified mediastinal and hilar lymph nodes are present.

Figure 3.

Representative histopathology hematoxylin and eosin-stained section from a lung transplant recipient with end-stage silicosis. Slide demonstrates silicosis with progressive massive fibrosis, based on conglomeration of mature silicotic nodules (asterisks), surrounding fibrosis, and substantial alteration of the normal lung architecture.

Patients with silicosis were significantly younger at the time of transplant than patients with nonsilicosis ILDs (43.1 ± 9.9 years vs 59.3 ± 7.1 years; p < 0.001; Table 1). All 7 patients with silicosis were male compared to 40 (58.0%) with nonsilicosis ILDs (p = 0.029; Table 1). All but 1 of the silicosis patients reported Hispanic/Latino ethnicity (Table 1).

Available records dating back to 1999 indicate there were no lung transplants performed at UCSD for silicosis before this study period. The first referral for lung transplantation for silicosis at UCSD occurred in 2018, and the first transplant surgery for silicosis was performed in 2020. From 2018-2023, we received 15 lung transplant referrals for silicosis, of which 7 were transplanted and 8 were declined. Due to the scope of this study, we cannot provide clinical information or factors affecting transplant candidacy for patients who did not undergo transplantation. Though notably, our institution’s process for candidacy assessment is no different for patients with ES silicosis compared to any other indication for transplant.

Stone countertop installation and fabrication, including ES products, was reported as the occupation for all 7 silicosis patients. Of these, 1 reported working fewer than 10 years, 3 (42.9%) reported working between 10 and 20 years, and 3 (42.9%) reported having worked in the industry for more than 20 years. Among the 3 patients for whom data were available, none reported having used personal respiratory protection at work. Occupational histories were unavailable for the nonsilicosis ILD transplant recipients.

Of the 7 patients with silicosis, 1 had a history of latent tuberculosis infection, 1 had a history of treated nontuberculous mycobacterial pulmonary infection, 1 had concomitant autoimmune disease, and none had lung cancer, comorbidities that could be causally linked to silica exposure.1, 2 The patient with autoimmune disease was diagnosed before transplant with both seropositive rheumatoid arthritis and antineutrophil cytoplasmic antibody-positive crescentic necrotizing glomerulonephritis.

There were no significant differences in pretransplant mean pulmonary artery pressure or functional status between lung transplant patients with silicosis and nonsilicosis ILDs (Table 1). However, before transplant, patients with silicosis had significantly lower mean percent predicted (PP) forced expiratory volume in 1 second (FEV1) (24.3 PP vs 46.6 PP; p < 0.001; Table 1 and Figure 4A), forced vital capacity (FVC) (28.7 PP vs 43.3 PP; p < 0.01; Table 1 and Figure 4B), and FEV1/FVC (73.9 vs 85.8; p = 0.007; Table 1 and Figure 4C) compared to patients with nonsilicosis ILDs.

Figure 4.

Pulmonary function test parameters pretransplant, post-transplant, and 1-year post-transplant among lung transplant patients with silicosis, n = 7, and nonsilicosis interstitial lung disease, n = 69. FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; ILD, interstitial lung disease; Txp, transplant. Student's t-test and Mann-Whitney U test were used (*p < 0.05, **p < 0.01, ***p < 0.001).

Perioperative management

The mean ischemic times for left and right donor lungs received by silicosis patients were significantly longer than nonsilicosis ILD patients (Table 2). No significant group differences were observed in intraoperative blood loss, post-transplant need for dialysis, post-transplant days on mechanical ventilation, and post-transplant days on extracorporeal membrane oxygenation (Table 2).

Table 2.

Perioperative Management for Lung Transplant Recipients With Silicosis and Nonsilicosis ILDs (n = 76)

Clinical Parameter	Silicosis	Nonsilicosis ILD	Total	p
n	7 (7.6%)	69 (90.8%)	76
Post-transplant PFTs
FEV1 PP	70.0 (19.0)	75.2 (20.9)	74.7 (20.7)	0.534a
FVC PP	65.0 (21.0)	71.4 (19.1)	70.8 (19.2)	0.408a
FEV1/FVC (%)	90.4 (7.5)	84.4 (8.9)	85.0 (8.9)	0.072b
Missingc	0 (0.0%)	2 (2.9%)	2 (2.6%)
Left donor lung ischemic time (minutes)	416.6 (127.7)	282.9 (97.1)	295.2 (106.7)	0.005b
Right donor lung ischemic time (minutes)	370.3 (132.6)	227.2 (86.6)	240.4 (99.7)	<0.001a
Intraoperative blood loss (ml)	492.9 (667.8)	391.2 (552.6)	400.6 (559.8)	0.925b
Days on mechanical ventilation post-transplant	2.0 (0.6)	2.6 (2.8)	2.6 (2.7)	0.929b
Days on ECMO post-transplant	0.0 (0.0)	0.1 (0.9)	0.2 (1.0)	>0.999b
Days on dialysis post-transplant	0.0 (0.0)	1.2 (6.5)	1.1 (6.2)	>0.999b

Abbreviations: ECMO, extracorporeal membrane oxygenation; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; ILD, interstitial lung disease; PFT, pulmonary function tests; PP, percent predicted.

Values shown as mean (standard deviation) or frequency (percent).

^aStudent's t-test.

^bMann-Whitney U test.

^cTwo patients died before obtaining post-transplant spirometry.

From pretransplant to the first recorded value after transplant, mean FEV1 PP and FVC PP significantly increased among both patients with silicosis and nonsilicosis ILDs (Figure 4A and B, respectively). There were no differences in FEV1 PP, FVC PP, or FEV1/FVC between the 2 groups post-transplant (Table 2; Figure 4A, B, and C, respectively).

One-Year Outcomes

At 1-year post-transplant, no differences were observed in overall survival (100% vs 95.7%; p = 0.574), presence of rejection, or functional status between lung transplant recipients with silicosis and nonsilicosis ILDs (Table 3). Of the 3 patients in the nonsilicosis ILD group who died before 1 year, 1 was due to presumed acute rejection and the other 2 were due to other causes. There were no group differences in the presence of rejection following logistic regression adjusting for age. Due to the absence of observed deaths in the silicosis group, the adjusted logistic regression model for survival failed to converge.

Table 3.

One-Year Post-Lung Transplant Outcomes for Recipients With Silicosis and Nonsilicosis ILDs (n = 76)

Clinical Outcome	Silicosis	Nonsilicosis ILD	Total	p
n	7 (7.6%)	69 (90.8%)	76
Alive at 1-year post-transplant	7 (100.0%)	66 (95.7%)	73 (96.1%)	0.574a
Patients with at least 1 rejection episode by 1-year post-transplant	1 (14.3%)	14 (20.3%)	15 (19.7%)	0.640a
Missingb	0 (0.0%)	5 (7.2%)	5 (6.6%)
Functional status at 1-year post-transplant
10%-30% (hospitalization indicated)	0 (0.0%)	0 (0.0%)	0 (0.0%)	0.600a
40%-70% (disabled; requiring assistance)	0 (0.0%)	6 (8.7%)	6 (7.9%)
80%-90% (symptomatic, but independent)	3 (42.9%)	31 (44.9%)	34 (44.7%)
100% (normal)	4 (57.1%)	27 (39.1%)	31 (40.8%)
Missingb	0 (0.0%)	5 (7.2%)	5 (6.6%)
1-year post-transplant PFTs
FEV1 PP	74.6 (14.0)	73.0 (34.1)	82.9 (20.3)	0.582c
FVC PP	74.3 (16.9)	74.6 (33.5)	84.5 (18.6)	0.552c
FEV1/FVC (%)	82.4 (9.4)	69.5 (29.1)	80.0 (12.0)	0.450c
Missingd	0 (0.0%)	9 (13.0%)	9 (11.8%)

Abbreviations: FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; ILD, interstitial lung disease; PFT, pulmonary function tests; PP, percent predicted.

Values shown as mean (standard deviation) or frequency (percent).

^aPearson's chi-square test.

^bTwo patients missing due to repatriation, and 3 died within the first year post-transplant.

^cMann-Whitney U test.

^dSix patients missing due to repatriation, and 3 died within the first year post-transplant.

There were no differences between post-transplant and 1-year FEV1 PP and FVC PP among patients with silicosis or nonsilicosis ILD (Figure 4A and B, respectively). There was a significant decrease in FEV1/FVC from immediate to 1-year post-transplant among nonsilicosis ILD (Figure 4C). There were no differences in FEV1, FVC PP, or FEV1/FVC between the 2 groups at 1 year (Table 3; Figure 4A, B, and C, respectively).

Discussion

This single-center study describes the first comprehensive analysis of lung transplant outcomes in ES countertop workers with silicosis in the United States. Notably, these patients were younger and had worse pretransplant lung function than nonsilicosis ILD transplants, emphasizing the growing occupational health crisis in California and worldwide. However, our findings demonstrate that despite worse pretransplant lung function, these patients have comparable 1-year post-transplant survival and pulmonary function to those transplanted for nonsilicosis ILDs.

Occupational exposure to ES dust in stone countertop workers has led to a global outbreak of severe and rapidly progressive ILD, typically in younger patients who experience substantial morbidity and mortality.4, 5, 9, 10, 11, 12, 13, 22, 24, 25 In the United States, most notably in California, several recent case series have highlighted similar patterns of disease burden,5, 6, 14 as ES products have become the most popular US countertop selection.26, 27 The rapid development of severe disease at younger ages in our patients with silicosis requiring lung transplantation aligns with the published literature (median age 46 years).4, 5, 6, 7, 14 Wu et al reported more severe hypoxemia (PaO₂ 64.8 vs 88.2 mm Hg), more rapid decline in lung function (FVC decline 587 vs 94.7 ml/y), and increased likelihood of being a transplant candidate (38.9% vs 3.2%) in silicosis from ES compared to natural stone exposures.⁴ Israeli ES workers evaluated in a lung transplant clinic reported approximately 20 years of ES exposure and were 52 years old at the time of transplant.²² In 169 ES workers in a multinational registry, 32% had PMF, the most severe form of silicosis.⁶ In contrast, workers in other RCS-exposed industries are typically older and less likely to have PMF if silicosis is diagnosed. In a follow-up assessment of Vermont granite stone carvers, only 14 of 356 workers had developed silicosis after a mean of 40 years of exposure, of whom only 4 had PMF.²⁸ In a study of 223 metal and nonmetal miners evaluated in a medical screening program in the western United States, with mean age 62 years and median 19 years of mining tenure, none of the 58 (26%) miners diagnosed with silicosis had PMF.²⁹ Since evidence-based treatments for silicosis are lacking, lung transplantation has become a growing and emergent necessity for an increasing number of workers in the ES industry.

There are 6 lung transplant centers in California, and from July 2023 to June 2024, UCSD performed approximately 13% of the state’s lung transplants.³⁰ Retrospective review of the Organ Procurement and Transplantation Network data identified 109 lung transplants performed nationally for silicosis from 1991-2023.³¹ Thirteen occurred in the state of California, and 8 (61.5%) of the California cases were in 2023 alone. Our study, which describes outcomes in 7 of these patients, represents a substantial portion of the recent lung transplants performed for silicosis in California.

Notably, UCSD had not recorded a single lung transplant for silicosis before 2020. There are likely many more undiagnosed cases of end-stage silicosis in ES workers. Though published reports have identified a modest number of cases in the United States, the number of stone fabrication workers nationwide is estimated at over 100,000.⁵ Prevalence data for silicosis in these workers are lacking but can be inferred from a large government-funded screening program in Australia, where 21% of 544 currently employed ES workers were diagnosed with silicosis after a median of just 12 years of work in the industry.³²

At the time of transplant, our silicosis patients had significantly worse lung function compared to nonsilicosis ILD patients, a finding described in previous reports of complicated ES silicosis. Eng et al found that recent silicosis patients had the lowest mean FEV1 PP among work-related lung disease transplant recipients,³³ and Rosengarten et al reported a lower FEV1 PP (31% vs 47%, p < 0.001) among patients transplanted for ES silicosis compared to IPF.¹⁵ The lower baseline lung function observed in our cohort further underscores the severity of disease compared to patients with nonsilicosis ILDs.

Singer et al reviewed the Organ Procurement and Transplantation Network database from 2005-2010 and found no difference in survival between patients transplanted for non-ES silicosis compared to other fibrotic lung diseases.²¹ Similarly, Perin et al found no difference in 5-year mortality between patients transplanted for non-ES silicosis vs IPF in a single center in Brazil before 2017.¹⁹ With the recent rise in popularity of ES products, data are limited regarding transplant outcomes for patients with ES silicosis, but our survival data are consistent with reports from Israel and China. Ju et al reported a cohort of 33 patients in China with occupational lung disease, 19 of whom had ES silicosis.¹⁸ There was no significant difference in 1-year mortality compared to patients transplanted for IPF, but patients with occupational lung disease did have lower FEV1 PP (62.1% vs 79.4%, p = 0.001) and FVC PP (68.5% vs 76.6%, p = 0.04) at 1 year.¹⁸ In contrast, our findings did not demonstrate a difference in spirometry values at 1 year. In Israel, Kramer et al found no difference in 1-year survival between patients transplanted for ES silicosis compared to all other lung transplants performed at their institution,²² and a follow-up study at 5 years post-transplant identified no survival difference compared to IPF.¹⁵ Neither of these studies reported post-transplant FEV1 or FVC values. Our study reaffirms the comparable 1-year post-transplant outcomes between ES silicosis and nonsilicosis ILD patients, including survival rate, functional status, and pulmonary function.

Surgical complications in patients undergoing lung transplantation for silicosis are notable. Perin et al reported increased intraoperative bleeding (1,709 vs 300 ml, p < 0.001), increased intraoperative red blood cell transfusions (1,035 vs 500 ml, p = 0.014), and increased total postoperative blood loss through chest tubes (4,757 vs 1,505 ml, p = 0.001) among patients transplanted for silicosis compared to IPF.¹⁹ Among patients with documented ES silicosis, Rosengarten et al reported severe adhesions in 12 of 17 cases and 4 documented intraoperative hemorrhages.¹⁵ Ju et al likewise reported increased rates of hemothorax (30.3% vs 4.4%, p < 0.001), possibly linked to fibrogenic dust-related pleural adhesions.¹⁸ The significantly longer ischemic times among recipients with ES silicosis in our study may be due to a similar cause, and this observation would align with our program’s clinical experience. Despite longer donor lung ischemic times, the prevalence of intraoperative hemorrhage (as defined by intraoperative blood loss) and other perioperative complications was comparable between the silicosis and nonsilicosis ILD groups. Further investigation is needed to characterize the extent of pleural disease among patients with end-stage silicosis and factors contributing to longer ischemic times.

The demographic characteristics of our silicosis patients mirror recent reports of silicosis outbreaks among Hispanic/Latino workers in the ES industry, particularly in the state of California. Fazio et al reported 52 cases of silicosis associated with ES in California from 2019-2022, with 98% being Spanish-speaking Latino immigrant men.¹⁴ Our study findings are similar, with 85.7% (6/7) self-reporting Hispanic/Latino ethnicity, reflecting the disproportionate impact on a community that faces numerous health disparities. Moreover, our cohort's exclusive male composition reflects the general gender distribution in dust-exposed industries and other ES workforces with silicosis.6, 14, 21, 31, 34, 35, 36 These demographic parallels underscore the urgent occupational health crisis affecting younger male workers facing life-threatening exposures in the stone countertop industry.

The limited available data on workplace exposures and exposure controls in medical and United Network for Organ Sharing records preclude in-depth assessment of strategies for prevention. Primary preventive strategies such as workplace engineering controls to reduce airborne dust levels, substitution of ES products with those containing lower-silica content, or elimination of ES countertop products altogether are undoubtably the most effective methods.26, 36 Accordingly, Australia banned the manufacture, supply, and use of ES products nationwide in 2024.³⁷ California, along with all other states in the United States, has a requirement for employers to provide medical surveillance for workers exposed to RCS. One study reports that, in the stone fabrication industry, nearly two-thirds of employers with recorded overexposures had not conducted medical surveillance.³⁷ Given the individual and societal costs of lung transplantation, our study underscores the importance of active medical surveillance of RCS-exposed workers alongside policies to assure effective prevention.

Our study has several strengths. This investigation represents a comprehensive evaluation of transplant outcomes among ES countertop workers in the United States, which is timely given the recent surge in ES dust exposure and related diseases. This study also has a well-defined comparator group and includes detailed perioperative and post-transplant information.

Limitations of this study include the small sample size of patients with ES silicosis. Regarding our primary outcome of rejection in the first year, we have an achieved power of 0.07. As a result, our study was underpowered to exclude even a large effect size on rejection in the first year. All else being equal, we would need to include a total of 15 silicosis and 144 nonsilicosis ILD patients to rule out a large effect size. Given there were no deaths among patients with silicosis, we cannot calculate the needed sample size to exclude a large effect size for difference in survival. Despite power limitations, the included transplant recipients represent a substantial proportion of transplanted ES workers in California. Other limitations include the short follow-up period of 1 year, which does not allow us to draw conclusions about long-term allograft outcomes or potential risk for development of extrapulmonary manifestations of silicosis, such as increased risk for autoimmunity, which may also affect survival.⁶ Future efforts to monitor transplant outcomes longitudinally will provide important insights. Finally, the silicosis patients were younger than nonsilicosis ILD patients, and their comparable survival might be attributed in part to confounding by age and fewer comorbidities, which this study was unable to address due to the modest number of silicosis cases.

In conclusion, our single institution retrospective review suggests that lung transplantation is a viable option for ES countertop workers who develop end-stage lung disease secondary to silicosis. The comparable 1-year outcomes and lack of intraoperative complications between silicosis and other ILD patients support the role of lung transplantation as a therapeutic option in this worker population, despite increased baseline disease severity before transplantation. Furthermore, the young age of affected individuals and the preventable nature of this occupational disease underscore the urgent need to improve workplace safety measures and regulatory oversight in the ES industry. Future studies with larger cohorts and longer follow-up periods are needed to fully understand the long-term outcomes and potential challenges specific to this patient population.

CRediT authorship contribution statement

R.R. contributed to study design, data collection, data analysis, and manuscript writing. B.L. and K.V. contributed to data collection and manuscript writing. S.G. contributed to data collection, data analysis, and manuscript writing. K.A. contributed to study design, data analysis, and review of the manuscript. J.H., C.R., E.G., C.M.L., G.Y., C.G., C.M., A.M.G., and T.A. contributed to interpretation of data and revision of the manuscript. All authors approve of the final version of the manuscript.

Disclosure statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Gordon Yung has been an expert witness for 2 cases of silicosis-related litigation. This was unpaid. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Funding and Acknowledgments: None.