SILICA EXPOSURES IN THE
METAL/NONMETAL (M/NM)
MINING INDUSTRY
Bruce B. Palmer, M.P.H.
Health Specialist
MSHA M/NM Western District
September 28, 2010
What is “Silica”?
SiO2 (e.g., sand, glass, etc.)
Silicates (e.g., asbestos) is a chemical
cousin
This presentation will only address
respirable crystalline silica in the quartz,
cristobalite, and tridymite forms
Types of Mines Where Silica is Found
Almost all mines – including coal
Percent in ore varies considerably, even
within same commodity and location
MSHA Targeting of Respirable Silica
MSHA has targeted respirable quartz
for 33 years; it has been a Government
Performance and Results Act (GPRA)
goal for approximately 8 years
What is GPRA??
GPRA – Government Performance and
Results Act, congressional legislation
that requires government agencies to
prepare strategic plans and annual
performance goals
In MSHA M/NM, GPRA health goals
have historically been associated with
sampling toxic contaminants
What is the Overall Objective of
M/NM GPRA Goals?
Encourage consistent sampling of toxic
contaminants at mines throughout the U.S.
Focus on the contaminants that have the
greatest likelihood of damaging miners’ health
Identify trends so far as feasible
BOTTOM LINE: Reduce exposure to miners
to toxic contaminants
FY2010 M/NM GPRA Goals
Included:
2010 Metal/Nonmetal Health Sampling Program
Goal: Reduce Work-Related Illnesses in Metal & Nonmetal Mines
Sampling Annually
10 Contaminants: Asbestos, Beryllium Dust, Calcium Oxide,
Cristobalite, Cyanide, Lead, Mercury, Radiation-Alpha, Radiation-
Gamma, Silica
100% of Identified Commodity Mines: Asbestos, Beryl-Beryllium
Ore, Ground Silica, Vermiculite, Cement, Lime, Crushed & Broken
Quartzite, Diatomaceous Earth (Diatomite), Ground Cristobalite,
Lead, Lead-Zinc Ore, Zinc, Gold, Uranium Ore, Uranium-Vanadium
Ore, Vanadium Ore
Sampling Every 5 Years
10 Contaminants: Chromium VI, Diesel Particulate, Noise,
Radiation-Alpha, Respirable Dust, Silver, Sulfuric Acid, Talc Fiber,
Welding Fumes
Reported Musculoskeletal Illnesses within Last 5 Years
20% of Mines Sampled Each Year
FY2010 M/NM GPRA Goals
included:
Reduce Work-Related Illnesses in Metal & Nonmetal Mines
Sampling Annually
10 Contaminants: Asbestos, Beryllium Dust, Calcium Oxide, Cristobalite, Cyanide,
Lead, Mercury, Radiation-Alpha, Radiation-Gamma, Silica
100% of Identified Commodity Mines: Asbestos, Beryl-Beryllium Ore, Ground
Silica, Vermiculite, Cement, Lime, Crushed & Broken Quartzite, Diatomaceous Earth
(Diatomite), Ground Cristobalite, Lead, Lead-Zinc Ore, Zinc, Gold, Uranium Ore,
Uranium-Vanadium Ore, Vanadium Ore
Sampling Every 5 Years
10 Contaminants: Chromium VI, Diesel Particulate, Noise, Radiation-Alpha,
Respirable Dust, Silver, Sulfuric Acid, Talc Fiber, Welding Fumes
Reported Musculoskeletal Illnesses within Last 5 Years
20% of Mines Sampled Each Year
FY2011 M/NM GPRA Goals will
change:
Emphasis on enforcement of 56/57.5002
M/NM sampling strategy will be to sample
20% of our mines each year during the next
5 years.
Our goal will be to increase the percentage of
mines conducting their own surveys.
In 5 years, ensure compliance of 56/57.5002
at all of our mines.
2005–2009 MSHA Sampling
for Respirable Dust (Silica)
Citable Overexposures > ½ TLV but Cumulative
(>TLV) but not < TLV
citable
5% 2% 12% 19%
Factors Affecting Overexposure
Trending
MSHA management commitment to
sampling
Mine management commitment to dust
controls
Training of inspectors
Commodity mined
Job sampled
Effectiveness of dust controls
What Does MSHA Require of
Mine Operators?
Comply with 56/57.5001, .5002, .5005, and
Part 58
What Does MSHA Require of
Mine Operators?
.5001: Not exceed 1973 ACGIH TLVs
What Does MSHA Require of
Mine Operators?
.5002: “Dust…surveys shall be
conducted as frequently as necessary to
determine the adequacy of control
measures”
What Does MSHA Require of
Mine Operators?
.5005: Control of Exposure
“…insofar as feasible, by prevention of contamination,
removal by exhaust ventilation, or by dilution with
uncontaminated air”
“…Whenever respiratory protective equipment is used
[implement] a program for selection, maintenance,
training, fitting, supervision, cleaning, and
use…consistent with…ANSI Z88.2-1969 [and
furnish/use] respirators approved by NIOSH under 42
CFR part 84 which are applicable and suitable for the
purpose intended”
What Does MSHA Require of
Mine Operators?
58.610: use of enclosed device or
respirators approved under 42 CFR 84
when abrasive blasting
What Does MSHA Require of
Mine Operators?
58.620: Drill Dust Control
“…effective dust control measures shall
be used…”
What Does MSHA Require of Mine
Operators for 56/57.5002?
A performance-based standard applicable to
each unique mining environment, not an
overarching prescriptive standard
Program Policy Letter coming out
How much is “enough”?
“…surveys shall be conducted as frequently as necessary to
determine the adequacy of control measures”
MSHA will ask for operator’s records as
evidence of their surveys
MSHA website will have more information
What Guidance Does the MSHA
Program Policy Manual Provide?
“The sampling and analytical methods
used by the mine operator should be
consistent with established scientific
principles….”
What if Operator Sampling Records
Show a Past overexposure?
Will MSHA issue a citation for
overexposure identified through operator
sampling?
– NO!
Can MSHA resample the job/location
where the operator exposure occurred?
– Of Course!
P-Codes
• What is a P-Code?
• A code added to MSHA sampling
documentation signifying that “citable
overexposure occurred, but all feasible
engineering and administrative controls have
been implemented…”
• When a P-Code is issued (by MSHA
headquarters with District recommendation)
any subsequent citation is not issued
BUT…
What About Issuing a P-Code?
• P-Codes apply to NOISE ONLY
• Also FYI…operators do not request P-Codes.
[Requests are initiated by MSHA District
Managers based on a history of noise
overexposure and good faith efforts of operators
to control the noise for the particular job &
location]
What is the Current MSHA M/NM
Standard?
Current standard is based on 1973
ACGIH TLV:
• Quartz: 10 mg/m3
% respirable Q + 2
• Cristobalite: ½ value calculated for quartz
• Tridymite: ½ value calculated for quartz
“Designed to limit exposures to 0.1 mg/m3”
Respirable Crystalline
Silica Standard
MSHA’s agenda is to publish a “notice of
proposed rule making” in 4/2011
See
http://www.msha.gov/REGS/UNIFIED/Ap
ril2010/1219-AB36.asp#
Check www.msha.gov for updates
Respirable Crystalline
Silica Standard
DOL/MSHA RIN: 1219-AB36 Publication ID: Spring 2010
Title: Respirable Crystalline Silica Standard
Abstract: Current standards limit exposures to quartz (crystalline silica) in respirable dust. The coal mining industry standard is based on the
formula 10 mg/m3 divided by the percentage of quartz where the quartz percent is greater than 5 percent calculated as an MRE equivalent
concentration. The metal and nonmetal mining industry standard is based on the 1973 American Conference of Governmental Industrial Hygienists
(ACGIH) Threshold Limit Values formula: 10 mg/m3 divided by the percentage of quartz plus 2. Overexposure to crystalline silica can result in some
miners developing silicosis, an irreversible but preventable lung disease, which ultimately may be fatal. Both formulas are designed to limit
exposures to 0.1 mg/m3 (100 ug) of silica. The Secretary of Labor's Advisory Committee on the Elimination of Pneumoconiosis Among Coal Mine
Workers made several recommendations related to reducing exposure to silica. NIOSH recommends a 50 ug/m3 exposure limit for respirable
crystalline silica. MSHA will publish a proposed rule to address miners' exposure to respirable crystalline silica.
Agency: Department of Labor(DOL) Priority: Other Significant
RIN Status: Previously published in the Unified Agenda Agenda Stage of Rulemaking: Long-Term Actions
Major: No Unfunded Mandates: No
CFR Citation: 30 CFR 56 to 57; 30 CFR 70 to 72; 30 CFR 90 (To search for a specific CFR, visit the Code of Federal Regulations.)
Legal Authority: 30 USC 811; 30 USC 813
Legal Deadline: None
Statement of Need: MSHA standards are outdated; current regulations may not protect workers from developing silicosis. Evidence indicates that
miners continue to develop silicosis. MSHA's proposed regulatory action exemplifies the agency's commitment to protecting the most vulnerable
populations while assuring broad-based compliance. MSHA will regulate based on sound science to eliminate or reduce the hazards with the
broadest and most serious consequences. MSHA intends to use OSHA’s work on the health effects and risk assessment, adapting it as necessary
for the mining industry.
Summary of the Legal Basis: Promulgation of this standard is authorized by sections 101 and 103 of the Federal Mine Safety and Health Act of
1977.
Alternatives: This rulemaking would amend and improve health protection from that afforded by the existing standard. MSHA will consider
alternative methods of addressing miners' exposure based on the capabilities of the sampling and analytical methods.
Anticipated Costs and Benefits: MSHA will prepare estimates of the anticipated costs and benefits associated with the proposed rule.
Risks: For over 70 years, toxicology information and epidemiological studies have shown that exposure to respirable crystalline silica presents
potential health risks to miners. These potential adverse health effects include simple silicosis and progressive massive fibrosis (lung scarring).
Evidence indicates that exposure to silica may cause cancer. MSHA believes that the health evidence forms a reasonable basis for reducing miners'
exposure to respirable crystalline silica.
Timetable:
Action Date FR Cite
NPRM 04/00/2011
Respirable Crystalline
Silica Standard
RISKS: For over 70 years, toxicology
information and epidemiological studies have
shown that exposure to respirable crystalline
silica presents potential health risks to miners.
These potential adverse health effects include
simple silicosis and progressive massive fibrosis
(lung scarring). Evidence indicates that
exposure to silica may cause cancer. MSHA
believes that the health evidence forms a
reasonable basis for reducing miners' exposure
to respirable crystalline silica.
Respirable Crystalline
Silica Standard
NEED: MSHA standards are outdated; current
regulations may not protect workers from developing
silicosis. Evidence indicates that miners continue to
develop silicosis. MSHA's proposed regulatory action
exemplifies the agency's commitment to protecting
the most vulnerable populations while assuring
broad-based compliance. MSHA will regulate based
on sound science to eliminate or reduce the hazards
with the broadest and most serious consequences.
MSHA intends to use OSHA’s work on the health
effects and risk assessment, adapting it as
necessary for the mining industry.
Respirable Crystalline
Silica Standard
ALTERNATIVES: This rulemaking would
amend and improve health protection from
that afforded by the existing standard. MSHA
will consider alternative methods of
addressing miners' exposure based on the
capabilities of the sampling and analytical
methods.
Respirable Crystalline
Silica Standard
ABSTRACT: Current standards limit exposures to quartz (crystalline silica)
in respirable dust. The metal and nonmetal mining industry standard is
based on the 1973 American Conference of Governmental Industrial
Hygienists (ACGIH) Threshold Limit Values formula: 10 mg/m3 divided by
the percentage of quartz plus 2. Overexposure to crystalline silica can
result in some miners developing silicosis, an irreversible but preventable
lung disease, which ultimately may be fatal. Formulas are designed to limit
exposures to 0.1 mg/m3 (100 ug) of silica. The Secretary of Labor's
Advisory Committee on the Elimination of Pneumoconiosis Among
Coal Mine Workers made several recommendations related to
reducing exposure to silica. NIOSH recommends a 50 ug/m3 exposure
limit for respirable crystalline silica. MSHA will publish a proposed rule
to address miners' exposure to respirable crystalline.
QUESTIONS?
