Silica in the Sand Business: Frac Sand Mining and a Wisconsin Silicosis Docket
By Paul E. Rosenfeld, M.S., Ph.D., Principal Environmental Chemist, RoseyFields LLC, Santa Monica, California
The sand behind the fracking boom
Hydraulic fracturing requires enormous volumes of high-purity silica sand, propped into fractured shale formations to hold them open once drilling fluid pressure is released, and much of that sand historically came from surface mines in western Wisconsin, whose exceptionally pure quartz deposits made the region a national frac sand mining hub. Dr. Paul E. Rosenfeld, M.S., Ph.D. of RoseyFields LLC has addressed the resulting community and worker silica exposure in Trempealeau County, Wisconsin litigation (Sylla, 2024; Drangstveit, 2024).
A concentrated docket in a single Wisconsin county
Multiple related silica exposure matters against High-Crush frac sand mining operations, both the Whitehall and Blair facilities, proceeded through the Circuit Court of Trempealeau County, Wisconsin, reflecting the geographic concentration of both the frac sand mining industry and the resulting exposure litigation in this specific region.
Why frac sand mining generates a distinctive fugitive dust profile
Unlike engineered-stone fabrication, which occurs indoors at a relatively small scale, frac sand mining, processing, and rail/truck transloading occur largely outdoors at industrial scale, generating fugitive respirable crystalline silica dust from blasting, crushing, screening, drying, and material handling operations that can travel substantial distances from the active mining area to surrounding residential and agricultural land.
Air dispersion modeling for fugitive dust sources
Because frac sand mining emissions arise from area and fugitive sources rather than a discrete stack, dispersion modeling for this industry requires specialized area-source and open-pit emission factor methodology within AERMOD, combined with meteorological data reflecting the specific topography of the western Wisconsin driftless region (US EPA, AP-42 Emission Factors for Sand and Gravel Processing).
The regulatory silica standard applied to both workers and community members
As in engineered-stone litigation, OSHA’s Respirable Crystalline Silica Standard establishes the occupational exposure limit of 50 micrograms per cubic meter as an 8-hour time-weighted average for mine and processing workers, while community exposure assessment for nearby residents relies on EPA and state ambient air quality benchmarks rather than the occupational standard, requiring the exposure analysis to address both populations under different regulatory frameworks (OSHA, 29 CFR 1910.1053).
Silicosis and lung cancer risk from crystalline silica
IARC’s classification of crystalline silica as carcinogenic to humans (Group 1) applies to occupational exposure in quarrying, mining, and processing settings, directly encompassing frac sand mining operations, while the separately documented fibrotic disease process, silicosis, can develop and progress independent of any cancer diagnosis (IARC, Vol 100C).
Blasting as a distinct and acute exposure event
Beyond routine mining and processing operations, blasting to fracture bedrock for sand extraction generates a short-duration but high-intensity fugitive dust plume, requiring a distinct acute exposure analysis for nearby residents and workers separate from the chronic, lower-level exposure associated with ongoing processing and transport operations.
Wisconsin’s regulatory response to the frac sand boom
As frac sand mining expanded rapidly in western Wisconsin during the 2010s, the state adopted specific air quality permitting and reclamation requirements for industrial sand mining operations, reflecting a regulatory recognition that this industry’s fugitive dust profile required standards beyond those developed for conventional aggregate mining (Wisconsin DNR, Industrial Sand Mining Air Permits).
Why the boom-and-bust nature of frac sand demand matters to exposure reconstruction
Because frac sand demand fluctuates sharply with national oil and gas drilling activity, individual mining facilities’ operating intensity, and therefore their emissions, can vary substantially year to year, requiring exposure reconstruction to account for facility-specific historical production records rather than assuming constant operating conditions across a worker’s or resident’s entire exposure period.
Why frac sand silica litigation remains geographically concentrated but nationally relevant
Although the litigation to date has concentrated in Wisconsin, Texas, and other major frac sand producing regions, the underlying fugitive dust modeling and silica dose-response methodology developed in this context is directly transferable to other industrial sand and aggregate mining silica exposure matters nationally. Dr. Rosenfeld’s firm profiles this silica and fugitive dust exposure assessment work in more detail at RoseyFields.com.
References
1. Sylla MJ, et al. v High-Crush Whitehall LLC. Case Nos. 2019-CV-63, 2019-CV-64, 2019-CV-65, 2019-CV-66, Circuit Court of Trempealeau County, Wisconsin.
2. Drangstveit L v High-Crush Blair LLC. Case No. 19-CV-66, Circuit Court of Trempealeau County, Wisconsin.
3. Occupational Safety and Health Administration. Occupational Exposure to Respirable Crystalline Silica. 29 CFR § 1910.1053.
4. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Silica Dust, Crystalline, in the Form of Quartz or Cristobalite. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 100C. Lyon, France: International Agency for Research on Cancer; 2012.
5. US Environmental Protection Agency. AP-42 Compilation of Air Emission Factors: Sand and Gravel Processing. Washington, DC: US EPA.
6. Wisconsin Department of Natural Resources. Industrial Sand Mining Air Permitting Guidance. Madison, WI: Wisconsin DNR.
7. US Environmental Protection Agency. Revisions to the Guideline on Air Quality Models. 40 CFR Part 51, Appendix W. Fed Regist. 2017;82(10):5182-5235.
8. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Silica. Atlanta, GA: US Department of Health and Human Services.
9. National Institute for Occupational Safety and Health. Health Hazard Evaluation: Frac Sand Mining and Processing. Cincinnati, OH: CDC.
10. Rose C, Heinzerling A, Patel K, Sack C, Wolff J, Zell-Baran L, Weissman D, et al. Severe silicosis in engineered stone fabrication workers — California, Colorado, Texas, and Washington, 2017-2019. MMWR Morb Mortal Wkly Rep. 2019;68(38):813-818.
11. US Mine Safety and Health Administration. Respirable Crystalline Silica Standard for Metal and Nonmetal Mines. 30 CFR Part 60.
12. Rosenfeld PE. RoseyFields LLC: Silica and Fugitive Dust Exposure Assessment. Santa Monica, CA: RoseyFields LLC; 2026.
13. Occupational Safety and Health Administration. Hazard Alert: Worker Exposure to Silica during Countertop Manufacturing, Finishing and Installation. Washington, DC: US Department of Labor.
14. Wisconsin Department of Health Services. Frac Sand Mining and Public Health. Madison, WI: WDHS.