Mining and Extraction Workers
Mining and Extraction Workers faced occupational asbestos exposure across multiple commodity sectors, including vermiculite, talc, taconite (iron ore), gold and copper, and quarry operations in naturally occurring asbestos (NOA) zones. This page is the cluster hub: it summarises each sub-type and links to dedicated sub-pages for depth. For workers and families seeking compensation, see W.R._Grace_Trust (vermiculite) and the related trust-fund pages linked below.[1][2]
Executive Summary
Mining and extraction work produced documented asbestos exposure in at least five distinct populations: vermiculite miners (the W.R. Grace Libby, Montana operation), talc miners (deposits contaminated with tremolite or anthophyllite), taconite miners (Minnesota iron ore), gold and copper miners (amphibole co-occurrence), and quarry and road-construction workers operating in naturally occurring asbestos (NOA) zones. Each sub-type has its own exposure mechanism, epidemiological evidence base, and compensation route.
The single most-cited cohort is the Libby vermiculite cohort, which produced an asbestosis standardized mortality ratio of 165.8 and elevated mesothelioma and pleural cancer mortality.[3] The largest trust fund tied to a mining operation is the W.R. Grace Asbestos PI Trust ($3 billion, established 2008; see W.R._Grace_Trust).
A defining regulatory gap shaped exposure across all sub-types: the Mine Safety and Health Administration (MSHA) maintained an asbestos permissible exposure limit of 2 fibers per cubic centimeter (f/cc) until 2008 — fourteen years after the Occupational Safety and Health Administration (OSHA) reduced its general-industry standard to 0.1 f/cc.[4][5] Mining workers were legally exposed during that window to concentrations OSHA had already determined to be unsafe for general industry.
At-a-Glance
Mining and extraction asbestos exposure at a glance:
- Asbestos is in the ore itself — Mining exposure differs from factory exposure in that fibers are released directly from raw mineral deposits during extraction, crushing, and processing — not from manufactured products[3]
- Five sub-types with dedicated coverage — Vermiculite, talc, taconite, gold/copper, and NOA quarry workers each carry distinct epidemiological signatures (see the cluster table below)
- Libby is the most-documented occupational asbestos disaster in U.S. mining — Workers at the W.R. Grace vermiculite mine showed asbestosis SMR 165.8 and mesothelioma SMR 15.1 in the NIOSH cohort follow-up[3]
- Talc mining risk depends on contamination, not talc itself — Workers at contaminated deposits (New York State; some cosmetic-grade) show excess mesothelioma; an asbestos-free Italian talc cohort (Val Chisone, n=1,749, 74-year follow-up) recorded zero pleural cancer deaths[6][7]
- Taconite miners carry measurable risk — A Minnesota cohort of 40,720 workers produced a mesothelioma SIR of 2.4 across 51 cases despite the ore being predominantly non-asbestiform amphibole[8]
- NOA quarry exposure occurs without commercial asbestos mining — Workers disturbing naturally occurring asbestos in road construction, sand and gravel pits, and crushed-stone quarries face documented exposure; El Dorado County, California recorded 15 mesothelioma cases (2013–2017) and 191 asbestos-related deaths (1999–2017)[9]
- MSHA was 14 years behind OSHA — The mining PEL was 2 f/cc through 2008 versus OSHA's 0.1 f/cc since 1994; sampling of 206 mines (2000–2007) found 14% of personal-exposure samples and 16% of analyzed mines exceeded 0.1 f/cc[4]
- Multiple overlapping compensation routes — The W.R. Grace Trust ($3B, vermiculite), the Imerys / Cyprus Mines proposed trust ($862M–$1.45B, talc), federal CARD Act / EEOICPA benefits for Libby workers, and personal-injury lawsuits against equipment, insulation, and product manufacturers can be combined[10]
Key Facts
| Measure | Finding (Source) |
|---|---|
| Libby vermiculite asbestos content (raw ore) | 21–26% by weight — Sullivan, Environ Health Perspect 2007 (PMID 17450227)[3] |
| Peak Libby dust exposure (dry-mill sweeping) | Up to 182 f/cc — 1,820× current OSHA permissible exposure limit (PEL) of 0.1 f/cc[3] |
| Libby asbestosis standardized mortality ratio | SMR 165.8 (95% CI 103.9–251.1) — Sullivan NIOSH cohort, n=1,672[3] |
| Libby mesothelioma SMR (1999–2001 window) | SMR 15.1 (95% CI 1.8–54.4) — Sullivan NIOSH cohort[3] |
| New York talc miners mesothelioma | Six post-1994 deaths confirmed; excess incidence 1990–2007 — Finkelstein, Am J Ind Med 2012 (PMID 22544543)[6] |
| Val Chisone (Italy) asbestos-free talc cohort | Zero pleural cancer deaths in n=1,749 over 74 years — Ciocan et al. 2022 (PMID 34390717)[7] |
| Minnesota taconite mesothelioma incidence | SIR 2.4 (95% CI 1.8–3.2) across 51 cases in n=40,720 (Allen et al., 2015)[8] |
| Homestake gold mine fiber exposure | 0.2–5.34 f/cc; 84% amphibole asbestos by electron microscopy — McDonald et al. 1978 (PMID 211890)[11] |
| Alaska road-construction NOA exposure | 3% of ~700 samples approached 0.1 f/cc; 40% of fibers confirmed asbestos by TEM — Perkins et al. 2008 (PMID 18629694)[12] |
| El Dorado County, California mesothelioma cases | 15 cases (2013–2017); 191 asbestos-related deaths (1999–2017) — NOA-attributed[9] |
| MSHA permissible exposure limit (asbestos) | 2 f/cc through 2008 versus OSHA 0.1 f/cc since 1994 (14-year regulatory gap)[4][5] |
| MSHA mine sampling (2000–2007) | 14% of personal-exposure samples and 16% of 181 mines analyzed exceeded 0.1 f/cc[4] |
| W.R. Grace Asbestos PI Trust | $3 billion funding; 130,000+ claims filed; $353M+ paid (see W.R._Grace_Trust)[10] |
Mining and Extraction Cluster Overview
The table below summarises each sub-type and links to dedicated sub-pages.
| Sub-Type | Primary Risk | Key Statistic | Dedicated Page |
|---|---|---|---|
| Asbestos miners | Extreme — direct extraction of commercial asbestos ore | Historic Penge / Quebec / Cape cohorts; very high asbestosis & mesothelioma rates | Asbestos_Miners |
| Vermiculite miners (Libby, Montana) | Extreme — Libby Amphibole Asbestos (LAA) | Asbestosis SMR 165.8; mesothelioma SMR 15.1 (Sullivan 2007) | Vermiculite_Miners |
| Talc miners (contaminated deposits) | High — tremolite / anthophyllite contamination | NY State excess mesothelioma; Val Chisone (asbestos-free) zero pleural cancer | Talc_Miners |
| Taconite (iron ore) miners | Elevated — predominantly non-asbestiform amphibole | Mesothelioma SIR 2.4 across n=40,720 (Allen 2015) | Taconite_Miners |
| Gold, copper, and other metal miners | Elevated — amphibole co-occurrence in ore bodies | Homestake: 84% amphibole fibers; 3× expected respiratory disease mortality | (covered below; no dedicated page yet) |
| NOA quarry / road-construction workers | Variable — disturbance of naturally occurring asbestos | El Dorado County: 15 mesothelioma cases (2013–2017); 191 ARD deaths (1999–2017) | NOA_Quarry_Workers |
See dedicated pages:
- Asbestos_Miners — direct asbestos-ore mining, historical cohorts
- Vermiculite_Miners — W.R. Grace Libby operation, LAA, CARD Act, trust mechanics
- Talc_Miners — New York, Val Chisone, international cohorts; Imerys / Johnson & Johnson litigation context
- Taconite_Miners — Minnesota Iron Range cohort, Reserve Mining litigation
- NOA_Quarry_Workers — USGS NOA framework, El Dorado, Arizona, Alaska road sites
Vermiculite Miners (Libby, Montana)
The W.R. Grace vermiculite mine near Libby, Montana operated from the early 1920s until 1990. W.R. Grace purchased the mine in 1963 and continued operations despite internal documentation by the early 1970s that the vermiculite was contaminated with amphibole asbestos — predominantly winchite, richterite, and tremolite, collectively known as Libby Amphibole Asbestos (LAA). The raw ore was 21–26% asbestos by weight, and concentrate shipped to 245 processing sites nationwide still contained 0.3–7.0% asbestos.[3][13]
The NIOSH cohort study tracked 1,672 white male workers hired between 1935 and 1981 and reported standardized mortality ratios of 165.8 for asbestosis, 1.7 for lung cancer, and 15.1 for mesothelioma during the 1999–2001 follow-up window.[3] Workers with cumulative exposure below 4.5 f/cc-years — equivalent to a 45-year career at the current OSHA PEL — still showed significantly elevated nonmalignant respiratory disease mortality.
The W.R. Grace Asbestos PI Trust was established in 2008 with $3 billion in funding and has paid more than $353 million across 130,000+ claims.[10] Federal benefits are additionally available to Libby-exposed workers under the Energy Employees Occupational Illness Compensation Program Act (EEOICPA) and the Center for Asbestos Related Disease (CARD) certification process. See: Vermiculite_Miners and W.R._Grace_Trust for filing mechanics and worker history.
Talc Miners
Talc itself is magnesium silicate and is not asbestos. Mesothelioma risk in talc mining comes from geological co-occurrence: some commercial talc deposits formed alongside amphibole asbestos (tremolite, anthophyllite, actinolite) and the ore was historically mined without separation. New York State deposits (Gouverneur Talc Company and successor operations in St. Lawrence County) contain 37–59% non-asbestiform tremolite plus asbestiform tremolite and anthophyllite fibers; Finkelstein's reanalysis of the regional cohort identified six mesothelioma deaths after 1994 and excess incidence during 1990–2007.[6]
The most important comparison case is the Val Chisone, Northern Italy talc deposit, evaluated as having no detectable asbestos contamination. The 74-year follow-up of 1,749 miners and millers (Ciocan, Pira, Coggiola, et al., 2022) recorded zero pleural cancer deaths and no excess lung cancer mortality, while pneumoconiosis attributable to silica was elevated.[7] The natural experiment is decisive: it is the asbestos contamination in some talc deposits, not talc itself, that drives mesothelioma risk.
The talc-mining story extends into the J&J / Imerys cosmetic-talc litigation; that companion story is summarised on the WHO_IARC_Talc_Probably_Carcinogenic_Group_2A page and developed in full on the dedicated worker-focused sub-page. See: Talc_Miners.
Taconite (Iron Ore) Miners
Taconite mining in Minnesota's Mesabi Iron Range and Michigan's Marquette Iron Range processes low-grade iron ore that releases elongate mineral particles (EMPs) during beneficiation. Allen et al. (2015) followed a cohort of 40,720 taconite workers employed between 1937 and 1983 and reported a standardized mesothelioma incidence ratio of 2.4 (95% CI 1.8–3.2) across 51 confirmed cases.[8] A subsequent cohort mortality analysis produced an SMR for mesothelioma of 2.77 (95% CI 1.87–3.96), and a nested case-control study found above-median EMP exposure carried a mesothelioma rate ratio of 2.25 versus below-median exposure.
The finding of excess mesothelioma in this population is described in the literature as "unique among studies of non-asbestiform amphiboles" because the dominant fibers in taconite are predominantly non-asbestiform and shorter than 5 μm. The contribution of commercial asbestos historically used in processing facility insulation and brake materials cannot be entirely excluded. See: Taconite_Miners.
Gold, Copper, and Other Metal Miners
The Homestake gold mine in Lead, South Dakota operated from 1876 through 2002 in ore containing cummingtonite-grunerite, a non-asbestiform amphibole. NIOSH industrial hygiene sampling measured underground fiber exposures of 0.2–4.01 f/cc and surface-mill exposures of 0.12–5.34 f/cc — 2× to 53× the current OSHA PEL — with 84% of fibers identified as amphibole asbestos by electron microscopy.[11] The retrospective cohort of 3,144 workers (1,321 with 21+ years of service) showed elevated tuberculosis (4× expected) and respiratory disease (3× expected) mortality. NIOSH concluded that "no single etiologic agent can be implicated" given concurrent arsenic and radon exposures, but the documented amphibole fiber burden was substantial.
Copper mining in Arizona — including historical Phelps Dodge and Magma Copper operations in Gila and Pinal Counties — produced asbestos exposure through naturally occurring amphibole and chrysotile in the ultramafic and serpentinite host rocks. Specific epidemiological cohort studies of copper miners with quantified asbestos co-exposure are limited compared with gold and vermiculite, but documented exposures have formed the basis for individual mesothelioma claims.
Uranium miners in Grants, New Mexico (cohort of 1,735 underground workers and 904 mill workers, 1955–1990) face dual radon and asbestos co-exposure; radon is the dominant carcinogenic agent in published analyses, but documented asbestos fibers from mine geological formations and from construction materials within mines contributed to the overall respiratory-disease burden.
Quarry Workers and Naturally Occurring Asbestos (NOA)
Quarry workers, road graders, sand and gravel pit operators, and construction crews working in geological zones with naturally occurring asbestos face a distinct exposure pathway: the act of disturbing NOA-bearing rock during excavation, crushing, blasting, or grading releases respirable fibers without any commercial mining of asbestos. The U.S. Geological Survey has mapped major NOA zones along the Appalachian Mountains and the Western Cordillera.[13] California's El Dorado County recorded approximately 15 mesothelioma cases between 2013 and 2017 and 191 asbestos-related deaths between 1999 and 2017. An Alaska road-construction project that hit tremolite/actinolite asbestos in local gravel produced exposures approaching 0.1 f/cc, with TEM analysis confirming approximately 40% of fibers were asbestos (Perkins et al., 2008).[12][9]
Arizona historically contained more than 100 sites with natural asbestos deposits, primarily chrysotile in central counties; mines around the Salt River Canyon collectively extracted approximately 75,000 tons of asbestos before the last mine closed in the early 1980s. See: NOA_Quarry_Workers.
The MSHA / OSHA Regulatory Gap
The Mine Safety and Health Administration (MSHA) has exclusive jurisdiction over U.S. mines, while OSHA covers general industry and construction. The two agencies have different regulatory histories on asbestos, and the gap mattered. OSHA lowered the asbestos permissible exposure limit to 0.1 f/cc in 1994; MSHA did not adopt the equivalent standard until 2008 — a 14-year window during which miners were legally exposed to concentrations OSHA had already classified as unsafe for general industry.[4][5] MSHA's sampling of 206 metal and nonmetal mines between 2000 and 2007 found 14% of 806 valid personal-exposure samples exceeded 0.1 f/cc, and 16% of 181 mines analyzed had at least one worker over the threshold. TEM analysis confirmed asbestos exposures above the limit in 23 samples at 5 mines, spanning iron and taconite, rock quarry, vermiculite, and wollastonite commodity groups. MSHA does require mandatory biannual inspections of every registered mine — a structural feature OSHA does not match — but the underlying exposure limit was the binding constraint.
Trust Funds and Compensation
Mining workers diagnosed with mesothelioma, asbestosis, or asbestos-related lung cancer can access several overlapping compensation sources depending on which sub-type applies:
- W.R. Grace Asbestos PI Trust — $3 billion funding, 130,000+ claims, $353M+ paid (vermiculite). See W.R._Grace_Trust for filing mechanics, payment percentage, scheduled values, and CARD Act / EEOICPA integration.[10]
- Imerys Talc America / Cyprus Mines proposed trust — Filed Chapter 11 in February 2019 and 2021 respectively; joint trust proposed at $862 million to $1.45 billion, in final bankruptcy negotiation as of 2026.[2]
- Babcock_and_Wilcox_Asbestos_Trust — Distinct from W.R. Grace; covers B&W asbestos-containing products used at many mining facilities.
- Personal-injury lawsuits against solvent defendants — Equipment suppliers, insulation contractors, brake-and-clutch manufacturers, and product manufacturers used at mine sites. Recent verdicts have reached the hundreds of millions of dollars in cosmetic-talc mesothelioma cases (WHO_IARC_Talc_Probably_Carcinogenic_Group_2A covers the J&J / Imerys litigation context).
Mining workers can pursue trust claims and personal-injury lawsuits in parallel. The right combination depends on the mine, employer, dates of work, and which downstream products contributed to exposure.
Documenting Mining Exposure for Claims
For workers and families building a mining-exposure claim:
- Employment history — Mine name, employer, dates, job titles, and specific tasks (mining, milling, crushing, dry sweeping, road grading) form the foundation of every trust-fund and litigation claim
- Industrial-hygiene records — Where preserved, MSHA inspection records and employer dust-sampling data provide quantitative exposure documentation
- Medical documentation — Low-dose CT is the standard for asbestos-exposure screening; standard chest x-rays miss roughly half of pleural changes. Pulmonary function testing, pathology reports, and treating-physician records all support the medical side of the claim
- Witness statements — Co-workers, supervisors, and union representatives can corroborate job duties, exposure conditions, and absence of respiratory protection
- CARD Act certification (Libby workers only) — A separate documentation track that supports both medical care and federal benefits eligibility
Frequently Asked Questions
Which mining sub-types carry the highest mesothelioma risk?
Vermiculite miners at the W.R. Grace operation in Libby, Montana have the most extreme documented exposures and the highest mesothelioma SMR among U.S. mining cohorts (15.1 in the 1999–2001 follow-up window).[3] Talc miners working contaminated deposits (New York State, some cosmetic-grade) and taconite miners in Minnesota also carry measurable mesothelioma risk. Gold miners at Homestake and quarry workers in NOA zones such as El Dorado County, California face elevated but generally lower SMR / SIR values.
How was MSHA different from OSHA?
MSHA had a much higher asbestos permissible exposure limit than OSHA for 14 years. OSHA reduced its asbestos PEL to 0.1 fibers per cubic centimeter in 1994; MSHA did not adopt the equivalent mining standard until 2008.[4][5] Miners during that window were legally exposed at concentrations OSHA had already determined to be unsafe. MSHA does conduct mandatory biannual inspections of every registered mine — a structural advantage OSHA does not match — but the underlying exposure limit was the binding constraint.
Does asbestos-free talc cause mesothelioma?
No. The longest-followed asbestos-free talc cohort — 1,749 workers at the Val Chisone mine in Northern Italy, followed across 74 years — recorded zero pleural cancer deaths and showed no elevation in lung cancer (Ciocan et al., 2022).[7] Silica-attributable pneumoconiosis was elevated, but mesothelioma was not. Excess mesothelioma in talc miners is driven by asbestos contamination of some commercial talc deposits, not by talc itself. See Talc_Miners for the worker-focused depth and WHO_IARC_Talc_Probably_Carcinogenic_Group_2A for the cosmetic-talc and IARC classification context.
What compensation is available to mining workers?
The W.R. Grace Asbestos PI Trust ($3 billion funding, 130,000+ claims, $353M+ paid) covers vermiculite-related exposure (see W.R._Grace_Trust). The proposed Imerys / Cyprus Mines talc trust ($862M–$1.45B) is in final bankruptcy negotiation. Workers exposed at gold, copper, iron, or other mines with documented asbestos co-contamination can pursue claims against equipment suppliers, insulation manufacturers, and product manufacturers through the broader asbestos trust system and direct personal-injury lawsuits. CARD Act certification and EEOICPA benefits are additionally available to Libby-exposed workers and residents.
Can family members file claims based on secondary exposure?
Yes. Secondary (take-home) exposure is extensively documented in mining communities. Miners carried asbestos fibers home on work clothing, boots, and hair; spouses and children developed asbestos-related disease through cleaning contaminated laundry or routine household contact. The ATSDR Libby community screening found pleural abnormalities in 17.8% of 6,668 screened adults, including residents with no occupational exposure of their own. Family members with confirmed asbestos-related disease can file trust-fund claims and pursue litigation against responsible parties.
What is the statute of limitations for mining exposure claims?
State statutes of limitations vary, typically 2–3 years from diagnosis. The discovery rule applied in most jurisdictions starts the clock at disease diagnosis rather than first exposure — critical protection given mesothelioma's 20–50 year latency period. Trust-fund deadlines are governed by separate trust documents and are generally longer than litigation statutes. Working with a mesothelioma firm experienced in mining-exposure claims is the most efficient way to identify every viable route within the relevant deadlines.
Quick Statistics
- 165.8 — Libby vermiculite cohort asbestosis standardized mortality ratio (Sullivan 2007, n=1,672)[3]
- 182 f/cc — Peak Libby dry-mill dust exposure, 1,820× current OSHA PEL[3]
- 2.4 — Standardized mesothelioma incidence ratio in the Minnesota taconite cohort (n=40,720; Allen 2015)[8]
- 0 — Pleural cancer deaths in the Val Chisone (Italy) asbestos-free talc cohort across 74 years of follow-up[7]
- 14 years — Lag between OSHA (1994) and MSHA (2008) reducing the asbestos PEL to 0.1 f/cc[4][5]
- 14% — Personal-exposure samples exceeding 0.1 f/cc in MSHA's 2000–2007 sampling of 206 metal and nonmetal mines[4]
- $3 billion — W.R. Grace Asbestos PI Trust funding (established 2008)[10]
- 130,000+ — Claims filed with the W.R. Grace Trust[10]
- 694 — Asbestos-related disease deaths among Libby residents, 1979–2011 (ATSDR)[13]
- 245 — Vermiculite processing sites that received Libby concentrate, each a secondary contamination source[13]
Get Help
If you or a family member worked in mining or extraction and has been diagnosed with mesothelioma, asbestosis, or an asbestos-related lung cancer, the team at Danziger & De Llano evaluates cases at no cost. Call (855) 699-5441 for a free consultation, or visit the firm's contact page.
Related Pages
- Asbestos_Miners — Direct asbestos-ore mining cohorts
- Vermiculite_Miners — W.R. Grace Libby operation (sub-page)
- Talc_Miners — Talc-mining sub-page including NY State, Val Chisone, international cohorts
- Taconite_Miners — Minnesota Iron Range cohort
- NOA_Quarry_Workers — Naturally occurring asbestos quarry and road-construction exposure
- W.R._Grace_Trust — Vermiculite mine trust fund mechanics
- Babcock_and_Wilcox_Asbestos_Trust — Distinct trust covering B&W asbestos products
- WHO_IARC_Talc_Probably_Carcinogenic_Group_2A — IARC classification and cosmetic-talc context
- Occupational_Exposure_Index — Complete occupational directory
References
- ↑ Danziger & De Llano. Asbestos Exposure Lawyers. dandell.com
- ↑ 2.0 2.1 Mesothelioma Lawyer Center. Asbestos and Mining. mesotheliomalawyercenter.org
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 Sullivan PA. Vermiculite, respiratory disease, and asbestos exposure in Libby, Montana: update of a cohort mortality study. Environmental Health Perspectives. 2007;115(4):579–585. PMID 17450227.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Mine Safety and Health Administration. Regulatory Economic Analysis: Final Rule on Asbestos Exposure Limit. Federal Register, February 29, 2008. msha.gov
- ↑ 5.0 5.1 5.2 5.3 5.4 Occupational Safety and Health Administration. 29 CFR 1910.1001 — Asbestos. osha.gov
- ↑ 6.0 6.1 6.2 Finkelstein MM. Malignant mesothelioma incidence among talc miners and millers in New York State. American Journal of Industrial Medicine. 2012. PMID 22544543.
- ↑ 7.0 7.1 7.2 7.3 7.4 Ciocan C, Pira E, Coggiola M, Franco N, Godono A, La Vecchia C, Negri E, Boffetta P. Mortality in the cohort of talc miners and millers from Val Chisone, Northern Italy: 74 years of follow-up. Environmental Research. 2022 Jan;203:111865. PMID 34390717.
- ↑ 8.0 8.1 8.2 8.3 Allen EM, Alexander BH, MacLehose RF, Nelson HH, Ramachandran G, Mandel JH. Cancer incidence among Minnesota taconite mining industry workers. Annals of Epidemiology. 2015 Nov;25(11):811-5. PMID 26381550.
- ↑ 9.0 9.1 9.2 California Geological Survey. Naturally-Occurring Asbestos in California. conservation.ca.gov
- ↑ 10.0 10.1 10.2 10.3 10.4 10.5 Danziger & De Llano. W.R. Grace Asbestos Trust Payments & Lawsuits. dandell.com
- ↑ 11.0 11.1 McDonald JC, Gibbs GW, Liddell FD, McDonald AD. Mortality after long exposure to cummingtonite-grunerite. American Review of Respiratory Disease. 1978 Aug;118(2):271-7. PMID 211890.
- ↑ 12.0 12.1 Perkins RA, Hargesheimer J, Vaara L. Evaluation of public and worker exposure due to naturally occurring asbestos in gravel discovered during a road construction project. Journal of Occupational and Environmental Hygiene. 2008. PMID 18629694.
- ↑ 13.0 13.1 13.2 13.3 Agency for Toxic Substances and Disease Registry. Where Is Asbestos Found? atsdr.cdc.gov