Date of Award

January 2025

Document Type

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: Artificial stone, a synthetic product that typically contains >90% silica mixed with resins and dyes, has become highly popular for kitchen and bathroom countertops. Meanwhile, silicosis outbreaks in workers who fabricate and install artificial stone countertops are increasingly being reported worldwide and in the US. Our objective is to better characterize work processes and exposures to respirable crystalline silica (RCS) among these workers in the United States. Methods: In collaboration with the Natural Stone Institute and the International Surface Fabricators Association, both trade organizations that represent the stone industry, an online survey was administered to stone countertop fabrication shops to assess shop characteristics and operations. We also collected RCS air monitoring reports. RCS 8-hour time-weighted averages (TWA-8 h) were obtained or calculated and compared to the OSHA permissible exposure limit (PEL) of 50 g/m3 and action level (AL) of 25 g/m3, as well as compared across independent variables of stone type, engineering control, and similar exposure group (SEG). Results: 257 countertop fabrication shops in 45 states completed the survey. Almost all (98%) shops reported fabricating both natural and artificial stone. 89% reported using all wet fabrication methods. And 20% reported performing medical surveillance. 46 shops submitted 292 usable RCS samples, with TWA 8-h ranging from 2.8 – 5,100.0 g/m3. 71 of 292 (24.3%) samples were above the AL, of which 27 (9.2%) were above the PEL. 20 of 46 (43.5%) shops had at least 1 sample above the AL. The highest exposures were with the use of small tools using dry methods. Overall, RCS exposures using dry methods were significantly higher than when using wet methods. Conclusion: Stone fabrication workers in shops across the United States are potentially overexposed to RCS despite widespread reported use of wet methods. Better engineering controls and better use of respiratory protection may reduce RCS exposure.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 06/16/2026

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