Research

JAMA Internal Medicine | Original Investigation

Silicosis Among Immigrant Engineered Stone (Quartz)
Countertop Fabrication Workers in California
Jane C. Fazio, MD; Sheiphali A. Gandhi, MD, MPH; Jennifer Flattery, MPH; Amy Heinzerling, MD, MPH;
Nader Kamangar, MD, MS; Nawal Afif, DO; Kristin J. Cummings, MD, MPH; Robert J. Harrison, MD, MPH
Editorial
IMPORTANCE Silicosis associated with inhalation of respirable crystalline silica among

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engineered stone countertop fabrication workers is an emerging health concern.
Supplemental content
OBJECTIVE To describe clinical, socioeconomic, and occupational characteristics of patientsdiagnosed with silicosis associated with engineered stone in California.
DESIGN, SETTING, AND PARTICIPANTS This case series included reported cases of silicosis
associated with fabrication of engineered stone countertops, as identified by statewide
surveillance by the California Department of Public Health (2019-2022). Data analysis
was performed from October 2022 to March 2023.
EXPOSURES Patient interviews and medical record abstractions were used to assess
occupational exposure to respirable crystalline silica, including duration of work tenure
and preventive measures undertaken.
MAIN OUTCOMES AND MEASURES Demographics, clinical characteristics, health careutilization, and clinical outcomes were obtained, including vital status, hypoxia,
and lung transplant.
RESULTS This case series identified 52 male patients meeting inclusion criteria; median (IQR)
age was 45 (40-49) years, and 51 were Latino immigrants. Ten (19%) were uninsured,and 20 (39%) had restricted-scope Medi-Cal; 25 (48%) presented initially to an emergency
department. A delay in diagnosis occurred in 30 (58%) patients, most commonly due toalternative initial diagnoses of bacterial pneumonia (9 [30%]) or tuberculosis (8 [27%]).
At diagnosis, 20 (38%) patients had advanced disease (progressive massive fibrosis) withseverely or very severely reduced forced expiratory volume in 1 second in 8 (18%) and 5(11%), respectively. Of the cases, 10 (19%) were fatal; median (IQR) age at death was 46(38-51) years, and 6 patients (12%) were alive with chronic resting hypoxia. Eleven werereferred for lung transplant: 3 underwent transplant with 1 fatality; 7 were declined
transplant, with 6 fatalities; and 1 died prior to listing. Median (IQR) work tenure was 15(10-20) years; 23 (45%) reported use of water suppression for dust mitigation, and 25 (48%)
continued to fabricate stone after being diagnosed with silicosis.
CONCLUSIONS AND RELEVANCE In this case series performed in California, silicosis associatedwith occupational exposure to dust from engineered stone primarily occurred among young
Latino immigrant men. Many patients presented with severe disease, and some cases were
fatal.

JAMA Intern Med. doi:10.1001/jamainternmed.2023.3295
Published online July 24, 2023.

Author Affiliations: Division of
Pulmonary, Critical Care, and Sleep
Medicine, David Geffen School of
Medicine at UCLA, Los Angeles,
California (Fazio, Kamangar);Occupational Health Branch,
California Department of Public
Health, Richmond (Fazio, Gandhi,
Flattery, Heinzerling, Cummings,
Harrison); Division of Pulmonary,Critical Care, and Sleep Medicine,
Olive View-UCLA Medical Center,
Los Angeles, California (Fazio,
Kamangar, Afif); Division of
Occupational, Environmental,
and Climate Medicine, University ofCalifornia, San Francisco (Gandhi).
Corresponding Author: Jane C.
Fazio, MD, Division of Pulmonary,Critical Care, and Sleep Medicine,David Geffen School of Medicine at
University of California, Los Angeles,
10833 Le Conte Ave, 43-229 CHS Box
951690, Los Angeles, CA 90095(jfazio@mednet.ucla.edu).

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Research Original Investigation

Silicosis Among Immigrant Engineered Stone (Quartz) Countertop Fabrication Workers in California

S

ilicosis is the most prevalent pneumoconiosis worldwide. It is a fibrotic interstitial lung disease resulting
from the occupational inhalation of respirable crystalline silica over decades. With exposure to higher dust levels,
the disease can also occur in acute and accelerated forms overshorter periods of time.1,2 Initially, patients are often asymptomatic. Subsequently, they may develop worsening respiratory symptoms and end-stage lung disease. As there are noeffective treatments, silicosis may lead to premature death orlung transplant. Although deaths from silicosis have declined in the US,3,4 workers in certain industries continue tobe exposed to silica dust.1,2
Recently, reported clusters of silicosis among engineeredstone countertop workers in countries other than the US havecalled attention to an accelerated and rapidly fatal form ofsilicosis.5-8 Engineered (artificial, synthetic, or quartz conglomerate) stone is manufactured in large facilities via mechanical crushing of quartz with polymer resins, dyes, andglass at high heat to produce a damage-resistant alternative tomarble or granite kitchen countertops. In contrast to naturalstone products, engineered stone contains more than 3 times
the silica content (90% vs 3%-30%).9,10 Driven by new construction, consumer taste, and imported slabs of engineeredstone that are less expensive than other countertop materials, demand has increased 23% annually over the past decade.11
At present, engineered stone is the most popular countertop
material in the US,12 with a global market value of more than
$20 billion in 2020.13 Manufacturers deliver slabs to shops
where fabricators cut, sand, and polish the material and generate levels of crystalline silica dust that may be hazardous.
Fabrication is frequently performed in shops where ventilation, dust control methods, and personal protective equipment are inadequate.14,15
Despite a comprehensive Occupational Safety and
Health Administration standard for exposure to silica dust,16
there are concerns about exposure and disease burden
among people who work with engineered stone. During
workplace inspections by California’s Division of Occupational Safety and Health, air sampling found levels above thepermissible exposure limit of 50 μg/m 3 among 25% of
employees and 51% of workplaces.14 Water suppression can
reduce crystalline silica dust exposure by 10-fold17 but isoften insufficient to reduce exposure below the permissible
exposure limit without local exhaust ventilation and appropriate personal protective equipment.17,18 In Queensland,
Australia, a comprehensive government screening program
found a silicosis prevalence of 19.5% among 1053 workers
who were screened.19 An estimated 100 000 stone fabricators in the US are at potential risk for silicosis associatedwith exposure to respirable crystalline silica.20
In the US, a case of silicosis associated with engineered stone
was reported in Texas in 2015,21 followed by 18 cases from 4
states in 2019 (6 from California).22 In California, a sentinel (fatal) case led to discovery of 2 others in the same workplace,which prompted workplace screening enforcement and identification of 5 additional cases (3 reported in 2019 and 2 discovered subsequently). The present case series, which includes
the 8 California cases that were previously reported,23 aims to
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Key Points
Question What are the characteristics of patients in California
with silicosis from occupational exposure to dust from engineeredstone (quartz), a popular material that is high in silica content andthat is used to fabricate countertops?
Findings In this case series of 52 patients, the median age was
45 years at diagnosis, and nearly all were Latino immigrant men.
Diagnosis was delayed in 58%, with 38% presenting withadvanced disease (progressive massive fibrosis), and 19% died.
Meaning In California, silicosis associated with occupational
exposure to dust from engineered stone primarily occurred among
young Latino immigrant men; many patients presented withsevere disease, and some cases were fatal.

describe silicosis associated with engineered stone in California workers through 2022, focusing on clinical presentation.

Methods
Case Identification
We identified cases from 2019 to 2022 through multiple methods: statewide hospital-based patient discharge data (International Statistical Classification of Diseases and Related Health
Problems, Tenth Revision code for silicosis [J62.X] from 2006
to 2021; if age younger than 50 years, requested and reviewed
medical records for engineered stone exposure); direct reporting by physicians or community members to the California Department of Public Health Occupational Health Branch; andpublic health follow-up of mandated medical testing following worksite investigations. We defined silicosis based on thedefinition of Occupational Respiratory Disease Surveillancefrom the National Institute for Occupational Safety and Health(NIOSH): history of occupational exposure to airborne silica
and either imaging or pathological findings characteristic ofsilicosis.24 We only included participants with a primary occupation of stone countertop fabricator and who regularly
worked with engineered stone. The institutional review boards
at the California Department of Public Health and the Olive
View-UCLA Medical Center Education and Research Instituteapproved the study. Informed consent was waived owing touse of deidentified data.

Medical Record Abstraction
We abstracted medical records and called patients or next of
kin to obtain further medical and occupational information if
necessary. Demographic data included date of birth, sex, raceand ethnicity, and birthplace and year immigrated to the US.
Self-reported occupational history included number of years
worked in stone fabrication (work tenure), current employment status, and employer. To assess respirator use, we asked,“How often do/did you wear a respirator”: never, sometimes,
or always. Type of respirator was not mutually exclusive andwas recorded as any use of N-95, half-face respirator with filters, or full-face respirator with filters. This information was
not easily standardized due to inconsistent interviews and use

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Silicosis Among Immigrant Engineered Stone (Quartz) Countertop Fabrication Workers in California

Figure 1. Yearly Case Counts for 52 Patients With Engineered
Stone–Associated Silicosis in California, 2010-2022
25

20

Cases, No.

of electronic medical record data. We obtained information
about whether workers regularly used water suppression for
dust mitigation and recorded it as a binary outcome (yes/no).
Workshop size was designated as small, medium, or large if lessthan 10, 10 to 50, or greater than 50 workers, respectively.
Dates of initial presentation, diagnosis, and death were collected to the month. Symptoms at presentation recorded wereshortness of breath, cough, wheezing, fever, weight loss, andchest/back pain. Additionally, we recorded if a patient had ever
had a pneumothorax. Delayed diagnosis was defined as a casewhere an alternative initial diagnosis for abnormal chest
imaging and/or symptoms was assigned prior to documentation of a presumed or confirmed diagnosis of silicosis. Timeto diagnosis of silicosis was quantified by subtracting presentation date from date of diagnosis. Smoking status was defined as greater than 20 packs of cigarettes over a lifetime
expressed in pack-years. We recorded comorbidities, specifically autoimmune and pulmonary diseases. We coded computed tomography imaging findings closest to time of diagnosis as simple silicosis (small nodular areas of fibrosis)
or progressive massive fibrosis (coalescent fibrotic masses
greater than 1 cm). We recorded lung transplant referrals, if any,
and whether the patient was declined, underwent transplant, or died prior to listing. We obtained outcomes: death
due to silicosis (time from diagnosis to death in months, andage at death) and alive with or without hypoxia, determinedby need for long-term supplemental oxygen.
We analyzed the pulmonary function test (PFT) results
closest to time of diagnosis based on American Thoracic Society and European Respiratory Society criteria.25 We defined obstruction as the ratio of forced expiratory volume in 1
second (FEV1) to forced vital capacity (FVC) below the lower
limit of normal, and restriction as the total lung capacity below the lower limit of normal. If total lung capacity was unavailable, we used FVC as a proxy. Severity of limitation was
graded using FEV1. Air trapping was defined as abnormal spirometry with total lung capacity above the upper limit of normal. We defined diffusion impairment as reduced diffusing
capacity of lung for carbon monoxide (DLCO) lower than thelower limit of normal and graded based on American Thoracic Society and European Respiratory Society guidelines.25
We calculated the predicted values for spirometry using the
global lung initiative other race equations and global lung initiative equations for lung volumes and DLCO.26 Lung biopsy
data included biopsy or explant done (yes/no), biopsy type, andpresence/absence of pathologic characteristics known to beconsistent with silicosis.27
We recorded health insurance as none/self-pay, fullscope Medi-Cal (California’s Medicaid program), restrictedMedi-Cal, private insurance, workers’ compensation, or Medicare. California has incrementally increased access to fullscope Medi-Cal for the oldest (age >50 years [2020]) and youngest (age <26 years [2022]) undocumented immigrants.28 As
those aged 26 to 49 years only qualify for restricted Medi-Cal
benefits, we used restricted-scope Medi-Cal or uninsured asa proxy for undocumented immigration status.29 Full-scope
Medi-Cal provides medical, dental, and vision insurance toeligible low-income California residents, while restricted Medi-

Original Investigation Research

15

10

5

0
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

Year of diagnosis

There were no reported cases of silicosis associated with engineered stone in
California prior to 2010.

Cal limits coverage to emergency and pregnancy-related care
for low-income individuals with undocumented immigration status.30 We obtained health care utilization data: location of initial presentation (urgent care/clinic or emergency department), if and how many emergency department visitsor hospitalizations due to respiratory symptoms, and cumulative hospital length of stay, if applicable.

Statistical Analysis
We calculated standard descriptive statistics for categorical
data (counts and percentage) and continuous data (median and
IQR) using R Studio, version 4.0.2 (R Foundation for Statistical Computing).31 This study followed the reporting guideline
for case series.

Results
Case Demographics
Between 2019 and 2022, we identified 52 patients in California with silicosis associated with engineered stone. Diagnosis dates ranged from 2010 to 2022; most of the diagnoses werein 2019 or later (Figure 1). Seven cases were identified from hospital discharge data, 37 from direct reporting, and 8 throughworkplace medical testing and public health follow-up. Thirtyseven cases (71%) were identified in Los Angeles County, 30
of whom sought care at Olive View-UCLA Medical Center, oneof the county’s 3 safety net hospitals. Cases were reported in
an additional 9 counties and represented 22 unique workplaces among 35 participants with known employment location. The median (IQR) age at diagnosis was 45 (40-49) years;
all but 1 patient were Spanish-speaking Latino immigrant men
from Mexico (32 [62%]), El Salvador (14 [27%]), and elsewhere in Central America (5 [10%]) (Table 1), with median (IQR)
time from immigration to diagnosis of 18 (15-22) years.

Occupational Exposure History
Median (IQR) work tenure was 15 (10-20) years, with 25 (48%)
patients continuing to fabricate stone after diagnosis at the timejamainternalmedicine.com(Reprinted) JAMA Internal Medicine Published online July 24, 2023

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Research Original Investigation

Silicosis Among Immigrant Engineered Stone (Quartz) Countertop Fabrication Workers in California

Table 1. Demographic Characteristics and Self-Reported Occupational
History of 52 Patients From California With Engineered
Stone–Associated Silicosis

Table 2. Clinical Characteristics and Outcomes of Patients
With Engineered Stone–Associated Silicosis

Demographic or occupational characteristic(No. with data available)

Clinical characteristic (No. with data available)

Overall (n = 52),
No. (%)

Demographic characteristics

Asymptomatic

7 (13)

45 (40-49)

Shortness of breath

45 (87)

Male sex (52)52 (100)

Cough

38 (73)

Chest/back pain

25 (48)18 (35)Latino51 (98)Weight loss

Othera1 (2)Fevers10 (19)Wheezing

8 (15)
5 (10)Country of birth (52)
Mexico32 (62)

Pneumothorax

El Salvador

14 (27)

Delayed diagnosis (52)Central America, other5 (10)

Initial delay in diagnosis

30 (58)Othera1 (2)Time to correct diagnosis, median (IQR), mo

3 (0-8)

Alternative initial diagnosis (30)

Occupational history
Years of work in engineered stone industry (51),median (IQR)

15 (10-20)

Continued working after diagnosis (52)
Still working

25 (48)

Not working

18 (35)

Unknown

9 (18)Engineering controls: water suppression methods (51)

23 (45)

Respirator use (47)
Sometimes

35 (74)

Always12 (26)

Type of respirator (37)

Pulmonary tuberculosis

8 (27)

Nontuberculous mycobacterial infection

3 (10)

Sarcoidosis

2 (7)Asthma2 (7)Bacterial pneumonia

9 (30)Other

6 (20)

Tobacco use (52)Current or former smoker

18 (36)

Pack-years among tobacco users, median (IQR)

3.5 (1.25-6)

Comorbidities (52)Autoimmune diseaseN-95

33 (89)Half-face respirator

17 (46)Full-face respirator

2 (5)No. of employees in workshop (35)<10

17 (49)10-50

17 (49)

>50

1 (2)

Further detail on the “Other” category cannot be disclosed due to small cellsize and protection of privacy.

the occupational history was obtained (Table 1). Water suppression for silica dust control was reported among 45% (23of 51). Of 47 patients with available data, respiratory personal
protective equipment was used “always” by 12 (26%) or “sometimes” by 35 (74%), with none indicating “never” (Table 1).
Workshop size was reported as small, medium, or large among
49% (17 of 35), 49% (17 of 35), or 2% (1 of 35), respectively.

Clinical Findings and Health Care Utilization
Forty-five patients (87%) reported at least 1 initial presenting
symptom (all with shortness of breath) (Table 2), which led tochest imaging. Median (IQR) time to diagnosis was 3 (0-8)
months. A delay in diagnosis occurred in 30 patients (58%),
among whom the alternative initial diagnosis was most commonly bacterial pneumonia (9 [30%]), active pulmonary tuberculosis (8 [27%]), and nontuberculous mycobacterial infection (3 [10%]). Of 5 patients with comorbid nontuberculous
mycobacterial infection and silicosis, the diagnosis of silicosis was delayed in the 3 patients where the mycobacterial inE4

Presenting symptoms (52)

Age at diagnosis (52), median (IQR), y

Race and ethnicity (52)aOverall (n = 52),
No. (%)1 (2)Rheumatoid arthritis

4 (8)Systemic sclerosis or CREST syndrome

1 (2)Nontuberculous mycobacterial infection

5 (10)

History of active pulmonary TB

1 (2)Other lung disease (COPD/asthma)

2 (4)Imaging (52)Predominant CT pattern
Simple silicosis

32 (62)

Progressive massive fibrosis

20 (38)Lung zone distribution
Upper

34 (65)Lower

5 (10)

Diffuse13 (25)Lymphadenopathy (52)None

6 (12)

Hilar only

4 (8)Mediastinal only

12 (23)

Hilar and mediastinal

30 (58)

Calcified lymphadenopathy (52)

17 (33)Ground glass opacities (51)

19 (37)

Bronchiectasis (52)

6 (12)

Cavitary lesions (51)

5 (10)

Pleural effusion (52)

6 (13)

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6 (12)

Myositis(continued)

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Silicosis Among Immigrant Engineered Stone (Quartz) Countertop Fabrication Workers in California

Table 2. Clinical Characteristics and Outcomes of Patients
With Engineered Stone–Associated Silicosis (continued)
Clinical characteristic (No. with data available)

Overall (n = 52),
No. (%)

PFTs (44)
PFT pattern (44)Normal13 (30)Restriction

24 (55)Mixed

6 (14)

Obstruction

1 (2)Severity of FEV1 reduction (44)Normal13 (20)Mild

9 (23)

Moderate

8 (18)

Moderate-severe

1 (2)Severe8 (18)

Very severe

5 (11)

Severity of DLCO reduction (43)
Normal23 (54)Mild

5 (12)

Moderate

11 (26)

Severe4 (9)Air trapping (30)

11 (37)

Lung biopsy (34)
Bronchoscopic
Transbronchial

29 (85)Lymph node

16 (47)

Surgical (video assisted)

5 (15)

Percutaneous needle

2 (6)Lung explant

1 (3)Pathologic features
Characteristic findings of silicosis

26 (76)

Birefringent crystals

19 (58)Granulomas

14 (41)Dust particles

15 (46)

Fibrotic nodules

12 (36)

Pulmonary alveolar proteinosis

3 (9)Outcomes (52)
Deceased due to silicosis

10 (19)Time from diagnosis to death, median (IQR), mo (9)Age at death, median (IQR), years (9)Original Investigation Researchsilicosis in 32 (62%) patients; representative cross-sectional
imaging is shown in Figure 2, and detailed imaging characteristics are presented in Table 2. Among 44 patients with available PFT results, 13 (30%) were normal, 24 (55%) restrictive(2 based on FVC alone), 6 (14%) were mixed, and 1 (2%) was
obstructive. In those with abnormal PFT results, air trapping
was observed in 11 (37%) patients. Results for DLCO were normal in 23 (54%) but reduced mildly in 5 (12%), moderately in
11 (26%), and severely in 4 (9%).
Of the patients, 34 had a lung biopsy; 26 (77%) biopsy results were consistent with a diagnosis of silicosis. Eight (24%)
patients were without characteristic findings of silicosis but
diagnosed based on clinical and imaging findings after alternative diagnoses were excluded (Table 2). Rheumatologic
disease was seen in 6 (12%) patients: rheumatoid arthritis in
4 (8%), and 1 case each had scleroderma and myositis. Concurrent infection with nontuberculous mycobacterial infection was present in 5 (10%) patients, 4 with Mycobacterium kansasii. Autoimmune serologies were collected with a positive
result for antinuclear antibody in 11 of 19 (58%) patients andrheumatoid factor in 4 of 16 (25%) patients. As of June 2023,
at least 10 (19%) had died due to silicosis: among 9 with available data, median (IQR) time from diagnosis to death was 35(19-52) months, and median (IQR) age at death was 46 (38-51)
years. Six (12%) were alive with resting hypoxia, 1 posttransplant. Thirty-five (67%) remained alive without hypoxia. Additionally, 11 patients were referred for lung transplant;
1 died before listing, 7 were formally declined (6 deceased asof May 2023), and 3 underwent transplant.
Of the cases, 25 (48%) initially presented to the emergency department, and 19 (37%) presented to a primary or urgent care clinician (Table 3). Ten patients (19%) were uninsured, 20 (38%) had restricted-scope Medi-Cal, 7 (13%) had
Medi-Cal, 8 (15%) had private insurance, and 7 (13%) had workers’ compensation. None had Medicare. Of 51 patients withavailable health care utilization data, 42 (82%) had 1 or more
respiratory-related emergency department visits, with a median (IQR) of 2.5 (1-4) visits. Hospitalization for respiratory
symptoms occurred among 31 (61%) patients with median(IQR) cumulative length of stay of 9.5 (4.3-19.8) days.

35 (19-52)
46 (38-51)

Alive with hypoxia

6 (12)

Alive without hypoxia

35 (67)

Referred for lung transplant

11 (21)

Formally declined

7 (13)

Underwent transplant

3 (6)Abbreviations: COPD, chronic obstructive pulmonary disease;
CREST, calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly,
and telangiectasia; CT, computed tomography; FEV1, forced expiratory volume
in 1 second; DLCO, diffusion capacity of the lung for carbon monoxide;
PFT, pulmonary function test; TB, tuberculosis.

fection was diagnosed first. Of the 8 patients with initial presumed active pulmonary tuberculosis, only 1 was confirmed
to have tuberculosis.
Chest computed tomography imaging demonstrated progressive massive fibrosis in 20 (38%) patients and simple

Discussion
The case series of 52 patients from California confirms clinical findings of silicosis in engineered stone countertop
fabrication workers that are similar to the clinical findings identified in other countries in recent years. 5-7 Silicosis wasdiagnosed in men in their mid-40s with an average work tenure of 15 years. Patients typically had delays in diagnosis
and presented after symptoms developed, with abnormal PFT
results and progressive massive fibrosis.32
To diagnose silicosis, a detailed occupational history should
be obtained in the patient’s native language, specifically asking about work in stone countertop fabrication and explicitly
asking about work with engineered stone. Duration of exposure should be assessed in terms of years worked and hours
per week, type of work done (eg, cutting large slabs, which isjamainternalmedicine.com(Reprinted) JAMA Internal Medicine Published online July 24, 2023

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Silicosis Among Immigrant Engineered Stone (Quartz) Countertop Fabrication Workers in California

Figure 2. Representative Chest Imaging From 2 Patients With Engineered Stone–Associated Silicosis in Different Stages of Disease
A Axial view of early simple silicosis

BC

D Coronal view of complicated silicosis

Axial view of complicated silicosis

Coronal view of early simple silicosis

Noncontrast computed tomography chest images demonstrate a case of early simple silicosis with scattered micronodules (A and B) and a case of complicatedsilicosis with progressive massive fibrosis, indicative of advanced disease (C and D).

more readily done with wet cutting, vs fabrication, which involves grinding and shaping edges and is more often done dry,thus posing increased risk), engineering controls used (ie, wetcutting methods), and type and regularity of respirator used
and whether the respirator was fit-tested.33 Imaging and history alone are sufficient for diagnosis24; however, if the diagnosis is uncertain, pulmonary consultation and bronchoscopic lung biopsy may be warranted.34 Management includes
serial monitoring with PFTs and imaging and evaluation forsigns and symptoms of associated conditions, including rheumatologic disease and mycobacterial infections.35 Clinicians
should report cases to the local state or federal Occupational
Safety and Health Administration office,36 notify their state
health department occupational health program,37 and provide patient resources from the California Department of
Public Health or other agencies.38
Our findings highlight the importance of timely accessto care for early diagnosis. The mainstay of managing patients with silicosis is minimizing further exposure. This canbe challenging, as inadequate dust suppression and poor compliance with respiratory protection regulations are common
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in this industry.14,15 The NIOSH hierarchy of controls for worker
safety prioritizes the elimination of hazardous exposure, followed by use of engineering controls; personal protective
equipment is least effective.39 In this case series, 48% of workers continued working in the industry after diagnosis, posing
a risk of ongoing silica exposure. Less than half reported working in shops regularly using water suppression; respiratory
protection was inconsistently used.

Limitations
This study has limitations. First, as we describe cases identified through clinician reporting, the findings may not be generalizable to all cases of silicosis associated with engineeredstone in California. Second, the mean time to diagnosis of 3
months should be interpreted cautiously, as over half of thecases were identified at Olive View-UCLA Medical Center,
where heightened clinician awareness led to earlier diagnosis. Third, self-report of occupational data may have resulted
in recall bias. Fourth, cross-sectional health utilization data provide only a limited snapshot and may underestimate services
used throughout a patient’s lifetime. Fifth, although many of

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Silicosis Among Immigrant Engineered Stone (Quartz) Countertop Fabrication Workers in California

Table 3. Health Care Utilization of Patients With Engineered
Stone–Associated Silicosis
Health care utilization characteristic(No. with data available)

Overall (n = 52),
No. (%)

Health insurance (52)
Uninsured or self-pay

10 (19)Restricted-scope Medi-Cal

20 (38)Full-scope Medi-Cal

7 (13)

Private insurance

8 (15)

Medicare0 (0)Workers’ compensation

7 (13)

Original Investigation Research

the patients in the case series may have been working as independent contractors, data on employment status were notformally collected. Sixth, although a substantial number of thepatients, including some of those who were uninsured or withrestricted-scope Medi-Cal, likely had an undocumented immigration status, we did not directly collect information about
whether individuals were undocumented immigrants. Finally, some patients may have received more medical carethan we were able to document, resulting in an underestimate of health care utilization.

Location of initial presentation (52)
Emergency department

25 (48)Outpatient clinic

19 (37)

Medical surveillance

8 (15)

Emergency department (52)Ever visited emergency department (52)42 (82)

No. of emergency department visits (42), median (IQR)

2.50 (1.00-4)

Hospitalization (51)Ever hospitalized for breathing

31 (61)

No. of times hospitalized (31), median (IQR)

2.0 (1-3.5)

Cumulative hospital length of stay per patient (30),
median (IQR), d

9.5 (4.3-19.8)

Conclusions
In this case series from California, silicosis associated with occupational exposure to dust from engineered stone primarily
occurred among young Latino immigrant men. Many presented with severe disease, and some cases were fatal. The findings highlight the urgent need for clinicians and public healthofficials to fully address the emerging issue of silicosis among
engineered stone countertop fabrication workers through measures such as protecting workers from exposure to silica dustin the workplace, timely diagnosis of disease, provision ofneeded medical care, and medical surveillance programs.

Drs Heinzerling, Cummings, and Harrison), and NIH
National Cancer Institute (1F32CA265103-01)(Dr Gandhi).

ARTICLE INFORMATION
Accepted for Publication: May 27, 2023.
Published Online: July 24, 2023.
doi:10.1001/jamainternmed.2023.3295
Author Contributions: Drs Fazio and Gandhi had
full access to all of the data in the study and takeresponsibility for the integrity of the data and theaccuracy of the data analysis. Drs Fazio and Gandhi
contributed equally to this work and serve as
co–first authors.
Concept and design: Fazio, Gandhi, Flattery,Heinzerling, Kamangar, Cummings, Harrison.
Acquisition, analysis, or interpretation of data:
Fazio, Gandhi, Flattery, Heinzerling, Kamangar,
Afif, Cummings.
Drafting of the manuscript: Fazio, Gandhi, Flattery,
Kamangar, Afif, Harrison.
Critical revision of the manuscript for important
intellectual content: Fazio, Gandhi, Flattery,Heinzerling, Kamangar, Cummings.
Statistical analysis: Fazio, Gandhi, Flattery.
Obtained funding: Flattery, Cummings.
Administrative, technical, or material support:
Gandhi, Flattery, Afif.
Supervision: Heinzerling, Kamangar, Cummings,
Harrison.
Conflict of Interest Disclosures: Dr Gandhi
reported grants from National Institutes of Health(NIH) National Cancer Institute (F32 CA265103)
outside the submitted work. Ms Flattery reported
grants from Centers for Disease Control andPrevention (CDC)/NIOSH during the conduct of thestudy. Dr Heinzerling reported grants from NIOSH
during the conduct of the study. No otherdisclosures were reported.
Funding/Support: This study was supported inpart by NIH National Heart, Lung, and Blood
Institute (T32HL72752) (Dr Fazio), CDC NIOSH(U60OH008468 and U19OH012293) (Ms Flattery,

Role of the Funder/Sponsor: The funders had norole in the design and conduct of the study;
collection, management, analysis, andinterpretation of the data; preparation, review,or approval of the manuscript; and decision tosubmit the manuscript for publication.
Disclaimer: The findings and conclusions in thisarticle are those of the authors and do notnecessarily represent the views or opinions of the
California Department of Public Health or the
California Health and Human Services Agency.
Data Sharing Statement: See the Supplement.
Additional Contributions: The authors would liketo acknowledge the physicians in the Division of
Pulmonary and Critical Care at Olive View-UCLA
Medical Center, including Keren Fogelfeld, MD,
Dennis Yick, MD, Nikhil Barot, MD, Roxana Y.
Hixson, MD, Kathryn H. Melamed, MD, and Kristin
Schwab Jensen, MD, for their outstanding patientcare, case identification, and reporting, and Vincent
H. Chan, MD, for his additional mentorship;
Fernanda Florez, Chelsea Woolsey, and Carolina
Espineli, California Department of Public HealthOccupational Health Branch, Richmond, for theircase surveillance efforts and data collection; andAsim Alam, MD, California Pacific Medical Center,for data collection. They did not receive
compensation beyond their regular salary.

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