Date of Award

January 2025

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Carrie A. Redlich

Second Advisor

Linda F. Cantley

Abstract

Background: An alarming rise in the number of cases of silicosis, a progressive and incurable lung disease, among engineered stone (ES) workers has prompted concern about the extent of the problem in the U.S. and whether ES can be used safely. Overexposure to high levels of respirable crystalline silica (RCS) during fabrication or installation of ES can increase the risk of developing a more severe case of silicosis. Medical surveillance studies on US ES workers are limited.Aim: The overall objective of this study was to better understand the state of medical surveillance for ES workers using employer surveys and employee data from members of the National Stone Institute (NSI) and the International Surface Fabricator Association (IFSA), two trade associations representing industry.

Methods: An electronic survey was given to NSI and ISFA member companies to assess industry characteristics and operations. Medical screening results, including medical questionnaires, spirometry reports, and chest x-rays findings, were obtained for 60 employees of one stone countertop fabrication company. Spirometry lower limit of normal for FEV1, FVC, and FEV1/FVC ratios were calculated using GLI data and NHANES data with age, height, sex-adjustment, and with and without race-adjustments, and descriptive analysis was performed.

Results: The survey completed by 266 employers indicated a median of 10 employees (range 1-460) per company. Most companies (95.9%) reported working with both natural and ES and performing countertop fabrication and installation (81.6%). A minority reported having performed air sampling for RCS (42.5%). Most employers reported the use of both hand tools (80.5%) and automated machines such as CNC (add%) to process stone. 62.4% of employers reported providing respiratory protection, but only 53.6% of these employers have a written protocol, and only 42.8% of these have performed respirator FIT testing. Only 18.8% of employers reported performing pre-placement exams, and over 50% of these were missing one or more key components, such as a chest X-ray. 60 employee medical screening and surveillance records from one fabrication company indicated that most employees were Hispanic males with an average age of 38.9 + 11.8 and an average employment tenure of 6.3 + 6.8. Most were either fabricators (26.7%) or installers (50%). Spirometry data indicated that using GLI normative values without race correction, 5.6% had findings suggestive of restrictive physiology, and none had obstructive physiology. Chest imaging B-read reports noted only 2/59 had abnormalities (1/2 perfusion and opacities and a 2nd hilar adenopathy), changes (especially opacities) concerning for possible early silicosis.

Conclusion: Overall, the majority of 266 ES stone companies are not performing recommended medical surveillance exams and workplace monitoring for silica. A review of medical surveillance records from 60 employees showed variable quality of testing. Almost all had normal spirometry and unremarkable chest imaging, except for one chest X-ray B-read suggestive of silicosis. The results identify opportunities to improve medical surveillance and compliance with OSHA silica regulations among ES employers and ES workers.

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This is an Open Access Thesis.

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