61384 Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 

DEPARTMENT OF LABOR 

Occupational Safety and Health 

Administration 

29 CFR Parts 1910, 1915, 1917, 1918, 

and 1926 

[Docket No. OSHA 2012–0023] 

RIN 1218–AC74 

Chemical Management and 

Permissible Exposure Limits (PELs) 

AGENCY: Occupational Safety and Health 

Administration (OSHA), DOL. 

ACTION: Request for Information (RFI). 

SUMMARY: OSHA is reviewing its overall 

approach to managing chemical 

exposures in the workplace and seeks 

stakeholder input about more effective 

and efficient approaches that addresses 

challenges found with the current 

regulatory approach. This review 

involves considering issues related to 

updating permissible exposure limits 

(PELs), as well as examining other 

strategies that could be implemented to 

address workplace conditions where 

workers are exposed to chemicals. The 

notice details the role of past court 

decisions on the Agency’s current 

approach to chemical management for 

the purpose of informing stakeholders of 

the legal framework in which the 

Agency must operate. It then describes 

possible modifications of existing 

processes, along with potential new 

sources of data and alternative 

approaches the Agency may consider. 

The Agency is particularly interested in 

information about how it may take 

advantage of newer approaches, given 

its legal requirements. This RFI is 

concerned primarily with chemicals 

that cause adverse health effects from 

long-term occupational exposure, and is 

not related to activities being conducted 

under Executive Order 13650, 

Improving Chemical Facility Safety and 

Security. 

DATES: Comments must be submitted by 

the following dates: 

Hard copy: must be submitted 

(postmarked or sent) by April 8, 2015. 

Electronic transmission or facsimile: 

must be submitted by April 8, 2015. 

ADDRESSES: Comments may be 

submitted by any of the following 

methods: 

Electronically: Submit comments 

electronically at: www.regulations.gov, 

which is the Federal eRulemaking 

Portal. Follow the instructions online 

for making electronic submissions. 

Fax: Submissions no longer than 10- 

pages (including attachments) may be 

faxed to the OSHA Docket Office at 

(202) 693–1648. 

Mail, hand delivery, express mail, or 

messenger or courier service: Copies 

must be submitted in triplicate (3) to the 

OSHA Docket Office, Docket No. 

OSHA–2012–0023, U.S. Department of 

Labor, Room N–2625, 200 Constitution 

Avenue NW., Washington, DC 20210. 

Deliveries (hand, express mail, 

messenger, and courier service) are 

accepted during the Department of 

Labor and Docket Office’s normal 

business hours, 8:15 a.m. to 4:45 p.m. 

(E.T.). 

Instructions: All submissions must 

include the Agency name and the OSHA 

docket number (i.e. OSHA–2012–0023). 

Submissions, including any personal 

information provided, are placed in the 

public docket without change and may 

be made available online at: 

www.regulations.gov. OSHA cautions 

against the inclusion of personally 

identifiable information (e.g., social 

security number, birth dates). 

If you submit scientific or technical 

studies or other results of scientific 

research, OSHA requests that you also 

provide the following information 

where it is available: (1) Identification of 

the funding source(s) and sponsoring 

organization(s) of the research; (2) the 

extent to which the research findings 

were reviewed by a potentially affected 

party prior to publication or submission 

to the docket, and identification of any 

such parties; and (3) the nature of any 

financial relationships (e.g., consulting 

agreements, expert witness support, or 

research funding) between investigators 

who conducted the research and any 

organization(s) or entities having an 

interest in the rulemaking. If you are 

submitting comments or testimony on 

the Agency’s scientific and technical 

analyses, OSHA requests that you 

disclose: (1) The nature of any financial 

relationships you may have with any 

organization(s) or entities having an 

interest in the rulemaking; and (2) the 

extent to which your comments or 

testimony were reviewed by an 

interested party prior to its submission. 

Disclosure of such information is 

intended to promote transparency and 

scientific integrity of data and technical 

information submitted to the record. 

This request is consistent with 

Executive Order 13563, issued on 

January 18, 2011, which instructs 

agencies to ensure the objectivity of any 

scientific and technological information 

used to support their regulatory actions. 

OSHA emphasizes that all material 

submitted to the rulemaking record will 

be considered by the Agency to develop 

the final rule and supporting analyses. 

Docket: To read or download 

submissions or other material in the 

docket go to: www.regulations.gov or the 

OSHA Docket Office at the address 

above. All documents in the docket are 

listed in the index; however, some 

information (e.g. copyrighted materials) 

is not publicly available to read or 

download through the Web site. All 

submissions, including copyrighted 

material, are available for inspection 

and copying at the OSHA Docket Office. 

FOR FURTHER INFORMATION CONTACT: 

General information and press inquiries: 

Mr. Frank Meilinger, Director, Office of 

Communications, U. S. Department of 

Labor, Room N–3647, 200 Constitution 

Avenue NW., Washington, DC 20210, 

telephone (202) 693–1999; email 

meilinger.francis2@dol.gov. Technical 

information: Ms. Lyn Penniman, Office 

of Physical Hazards, OSHA, Room N– 

3718, 200 Constitution Avenue NW., 

Washington, DC 20210, telephone (202) 

693–1950; email penniman.lyn@dol.gov. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Purpose 

II. Legal Requirements for OSHA Standards 

A. Significant Risk of a Material 

Impairment: The Benzene Case 

B. Technological and Economic Feasibility 

C. The Substantial Evidence Test 

III. History of OSHA’s Efforts To Establish 

PELs 

A. Adopting the PELs in 1971 

B. The 1989 PELs Update 

C. The 1989 PELs Update is Vacated 

D. Revising OSHA’s PELs in the Wake of 

the Eleventh Circuit Decision 

IV. Reconsideration of Current Rulemaking 

Processes 

A. Considerations for Risk Assessment 

Methods 

1. Current Quantitative Risk Assessment 

Methods Typically Used by OSHA To 

Support 6(b) Single Substance 

Rulemaking 

2. Proposed Tiered Approach to Risk 

Assessment in Support of Updating PELs 

for Chemical Substances 

a. General Description and Rationale of 

Tiered Approach 

b. Hazard Identification and Dose– 

Response Analysis in the Observed 

Range 

c. Derivation of Low-End Toxicity 

Exposure (LETE) 

d. Margin of Exposure (MOE) as a Decision 

Tool for Low Dose Extrapolation 

e. Extrapolation Below the Observed Range 

3. Chemical Grouping for Risk Assessment 

a. Background on Chemical Grouping 

b. Methods of Gap Analysis and Filling 

i. Read-Across Method 

ii. Trend Analysis 

iii. QSAR 

iv. Threshold of Toxicological Concern 

4. Use of Systems Biology and Other 

Emerging Test Data in Risk Assessment 

B. Considerations for Technological 

Feasibility 

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Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 61385 

1. Legal Background of Technological 

Feasibility 

2. Current Methodology of the 

Technological Feasibility Requirement 

3. Role of Exposure Modeling in 

Technological Feasibility 

a. Computational Fluid Dynamics 

Modeling To Predict Workplace 

Exposures 

b. The Potential Role of REACH in 

Technological Feasibility 

c. Technological Feasibility Analysis With 

a Focus on Industries with Highest 

Exposures 

C. Economic Feasibility for Health 

Standards 

1. OSHA’s Current Approach to Economic 

Feasibility 

2. Alternative Approaches to Formulating 

Health Standards that Might Accelerate 

the Economic Feasibility Analysis 

3. Alternative Analytical Approaches to 

Economic Feasibility in Health 

Standards 

4. Approaches to Economic Feasibility 

Analysis for a Comprehensive PELs 

Update 

V. Recent Developments and Potential 

Alternative Approaches 

A. Sources of Information About Chemical 

Hazards 

1. EPA’s High Production Volume 

Chemicals 

2. EPA’s CompTox and ToxCast 

3. Production and Use Data Under EPA’s 

Chemical Data Reporting Rule 

4. Structure-Activity Data for Chemical 

Grouping 

5. REACH: Registration, Evaluation, 

Authorization, and Restriction of 

Chemicals in the European Union (EU) 

B. Non-OEL Approaches to Chemical 

Management 

1. Informed Substitution 

2. Hazard Communication and the Globally 

Harmonized System (GHS) 

3. Health Hazard Banding 

4. Occupational Exposure Bands 

5. Control Banding 

6. Task-based Exposure Assessment and 

Control Approaches 

VI. Authority and Signature 

Appendix A: History, Legal Background and 

Significant Court Decisions 

Appendix B: 1989 PELs Table 

List of References by Exhibit Number 

List of Acronyms: Request for 

Information on Chemical Management 

and Permissible Exposure Limits 

ACGIH American Conference of 

Governmental Industrial Hygienists 

ADI Allowable Daily Intake 

AIHA American Industrial Hygiene 

Association 

AISI American Iron and Steel Institute 

ANSI American National Standards 

Institute 

APHA American Public Health Association 

ATSDR Agency for Toxic Substances 

Disease Registry 

BAuA Federal Institute for Occupational 

Safety and Health (Germany) 

BMD Benchmark Dose 

BMDL Benchmark Dose Low 

BMR Benchmark Response 

CDR Chemical Data Reporting 

CFD Computational Fluid Dynamics 

COSHH Control of Substances Hazardous to 

Health (U.K.) 

CrVI Hexavalent Chromium 

CSTEE Scientific Committee on Toxicity, 

Ecotoxicity and the Environment (E.U.) 

CT Control Technology 

DfE Design for the Environment (EPA) 

DHHS Department of Health and Human 

Services (U.S.) 

DMEL Derived Minimal Effect Level 

DNEL Derived No Effect Level 

DOE Washington Department of Ecology 

DOL Department of Labor (U.S.) 

ECB European Chemicals Bureau (E.U.) 

ECHA European Chemicals Agency (E.U.) 

EPA Environmental Protection Agency 

(U.S.) 

ES Exposure Scenario 

EU European Union 

FDA Food and Drug Administration (U.S.) 

GAO Government Accountability Office 

(U.S.) 

GHS Globally Harmonized System for the 

Classification and Labeling of Chemicals 

HazCom 2012 Revised OSHA Hazard 

Communication Standard 

HCS Hazard Communication Standard 

(OSHA) 

HHE Health Hazard Evaluation (NIOSH) 

HPV High Production Volume (EPA) 

HPVIS High Production Volume 

Information System (EPA) 

HSE Health and Safety Executive (U.K.) 

HTS High Throughput Screening 

IFA Federation of Institutions for Statutory 

Accident Insurance and Prevention 

(Germany) 

IMIS Integrated Management Information 

System (OSHA) 

IPCS World Health Organization 

International Programme on Chemical 

Safety 

IRIS Integrated Risk Information System 

(EPA) 

ISTAS Institute of Work, Environment, and 

Health (Spain) 

ITC Interagency Testing Committee (EPA 

TSCA) 

IUR Inventory Update Reporting 

LETE Low-end Toxicity Exposure 

LOAEL Lowest Observed Adverse Effect 

Level 

LOD Limit of Detection 

LTFE Lowest Technologically Feasible 

Exposure 

MA DEP Massachusetts Department of 

Environmental Protection 

MIBK Methyl isobutyl ketone 

MOA Modes of Action 

MOE Margin of Exposure 

MRL Minimal Risk Level 

NAICS North American Industry 

Classification System 

NCGC National Institutes of Health 

Chemical Genomics Center 

NIEHS National Institute of Environmental 

Health Sciences (U.S.) 

NIOSH National Institute for Occupational 

Safety and Health (U.S.) 

NIST National Institute of Standards and 

Technology (U.S.) 

NMCSD Navy Medical Center San Diego 

NOAEL No Observed Adverse Effect Level 

NOES National Occupational Exposure 

Survey 

NORA National Occupational Research 

Agenda (NIOSH) 

NPRM Notice of Proposed Rulemaking 

(OSHA) 

NRC National Research Council (U.S., 

private) 

NTP National Toxicology Program (U.S.) 

OECD Organization for Economic 

Cooperation and Development (multiple 

countries, private) 

OEL Occupational Exposure Limit 

OPPT Office of Pollution Prevention and 

Toxics (EPA) 

OSHA Occupational Safety and Health 

Administration 

OTA Massachusetts Office of Technical 

Assistance and Technology 

PBT Persistent, Bioaccumulative and Toxic 

PBZ Personal Breathing Zone 

PCRARM (EPA) Presidential/Congressional 

Commission on Risk Assessment and Risk 

Management 

PEL Permissible Exposure Limits 

PMN Pre-manufacture Notification (EPA) 

PNEC Predicted No Effect Concentration 

POD Point of Departure 

PPE Personal Protective Equipment 

PPM Parts Per Million 

QCAT Quick Chemical Assessment Tool 

(DOE) 

QSAR Quantitative Structure-Activity 

Relationship 

REACH Registration, Evaluation, 

Authorization and Restriction of Chemicals 

(E.U.) 

REL Recommended Exposure Level 

RfC Reference Concentration 

RFI Request for Information 

SAR Structural Activity Relation 

SBREFA Small Business Regulatory 

Enforcement Fairness Act (U.S.) 

SDS Safety Data Sheet 

SEP Special Emphasis Program 

SIC Standards Industrial Classification 

SIDS Screening Information Data Set 

(OECD) 

STEL Short-term Exposure Limit 

TLV Threshold Value Limit (ACGIH) 

TSCA Toxic Substances Control Act (EPA) 

TTC Threshold of Toxicological Concern 

TWA Time-weighted Average 

vPvB Very Persistent and Very 

Bioaccumulative 

WEEL Workplace Environmental Exposure 

Level (AIHA) 

I. Purpose 

The purpose of this Request for 

Information (RFI) is to present 

background information and request 

comment on a number of technical 

issues related to aspects of OSHA’s 

rulemaking process for chemical 

hazards in the workplace. In particular, 

the purpose of the RFI is to: 

• Review OSHA’s current approach to 

chemical regulation in its historical 

context; 

• Describe and explore other possible 

approaches that may be relevant to 

future strategies to reduce and control 

exposure to chemicals in the workplace; 

and 

• Inform the public and obtain public 

input on the best approaches for the 

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61386 Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 

Agency to advance the development and 

implementation of approaches to reduce 

or eliminate harmful chemical 

exposures in the 21st century 

workplace. 

By all estimates, the number of 

chemicals found in workplaces today far 

exceeds the number which OSHA 

regulates, and is growing rapidly. There 

is no single source recording all 

chemicals available in commerce. 

Through its Chemical Data Reporting 

Rule, EPA collects information on 

chemicals manufactured or imported at 

a single site at 25,000 pounds or greater; 

currently this number exceeds 7,674 

chemicals (U.S. EPA, 2013a; Ex. #1) 

The American Chemistry Council 

estimates that approximately 8,300 

chemicals (or about 10 percent of the 

87,000 chemicals in the TSCA 

inventory) are actually in commerce in 

significant amounts (Hogue, 2007; Ex. 

#2). By contrast the European Chemicals 

Agency database contains 10,203 unique 

substances (as of 9/12/2013) (ECHA, 

2013; Ex. #3). Of these, OSHA has 

occupational exposure limits for only 

about 470 substances. Most of these are 

listed as simple limits and appear in 

tables (referred to as ‘‘Z-tables’’) in 29 

CFR 1910.1000, Air Contaminants, 

Subpart Z, Toxic and Hazardous 

Substances; Ex. #4. Approximately 30 

have been adopted by OSHA as a part 

of a comprehensive standard, and 

include a number of additional 

requirements such as regulated areas, air 

sampling, medical monitoring, and 

training However, with few exceptions, 

OSHA’s permissible exposure limits, 

(PELs), which specify the amount of a 

particular chemical substance allowed 

in workplace air, have not been updated 

since they were established in 1971 

under expedited procedures available in 

the short period after the OSH Act’s 

adoption (see 29 CFR 1910.1000; Ex. #4, 

1915.1000; Ex. #5, and 1926.55; Ex. #6). 

Yet, in many instances, scientific 

evidence has accumulated suggesting 

that the current limits are not 

sufficiently protective. Although OSHA 

has attempted to update its PELs, the 

Agency has not been successful, except 

through the promulgation of a relatively 

few substance-specific health standard 

rulemakings (e.g., benzene, cadmium, 

lead, and asbestos). 

The most significant effort to update 

the PELs occurred in 1989 when OSHA 

tried to update many of its outdated 

PELs and to create new PELs for other 

substances in a single rulemaking 

covering general industry PELs. After 

public notice and comment, the Agency 

published a general industry rule that 

lowered PELs for 212 chemicals and 

added new PELs for 164 more (54 FR 

2332; Ex. #7). Appendix B to this 

Request for Information contains the 

table of PELs from the 1989 Air 

Contaminants Final Rule. The table 

includes both the PELs originally 

adopted by OSHA in 1971 and the PELs 

established under the 1989 final rule. 

While the Agency presented analyses of 

the risks associated with these 

chemicals, as well as the analyses of the 

economic and technological feasibility 

of the proposed limits for these 

chemicals, these analyses were not as 

detailed as those OSHA would have 

prepared for individual rulemakings. 

The final rule was challenged by both 

industry and labor groups. The 1989 

PEL update was vacated by the Eleventh 

Circuit Court of Appeals because it 

found that OSHA had not made 

sufficiently detailed findings that each 

new PEL would eliminate significant 

risk and would be feasible in each 

industry in which the chemical was 

used. (AFL–CIO v. OSHA, 965 F.2d 962 

(11th Cir. 1992) (the Air Contaminants 

case; Ex. #8). This decision is discussed 

further below and in Appendix A. 

Despite these challenges, health 

professionals and labor and industry 

groups have continued to support 

addressing PELs which may be outdated 

and or inconsistent with the best 

available current science. The 1989 Air 

Contaminants rulemaking effort was 

supported by the American Industrial 

Hygiene Association (AIHA), the 

American Conference of Governmental 

Industrial Hygienists (ACGIH), and the 

American Public Health Association 

(APHA), among many other professional 

organizations and associations 

representing both industry and labor. In 

an October 2012 survey, members of the 

AIHA identified updating OSHA PELs 

as their number one policy priority. The 

U.S. Chamber of Commerce, in a letter 

dated April 8, 2011 to then Deputy 

Secretary of Labor, Seth Harris, also 

supported updating OSHA’s PELs. 

Much has changed in the world since 

the OSH Act was signed in 1970. 

However, workers are essentially 

covered by the same PELs as they were 

forty years ago. And while OSHA has 

been given no new tools or increased 

resources to control workplace 

exposures, it has had to conduct 

increasingly complex analyses, which 

has effectively slowed the process. The 

purpose of this RFI is for OSHA to 

solicit information as to the best 

approach(es) for the Agency to help 

employers and employees devise and 

implement risk management strategies 

to reduce or eliminate chemical 

exposures in the 21st century workplace 

environment. This is likely to involve a 

multi-faceted plan that may include 

changing or improving OSHA policies 

and procedures regarding the derivation 

and implementation of PELs, as well as 

pursuing new strategies to improve 

chemical management in the workplace. 

The Agency is publishing this notice to 

inform the public of its consideration of 

these issues, as well as solicit public 

input that can be used to inform further 

deliberations, and the determination of 

an appropriate approach. 

II. Legal Requirements for OSHA 

Standards 

In the past, OSHA has received many 

suggestions for updating its PELs, but 

these suggestions often do not take 

account of the requirements imposed by 

the OSH Act, and thus have been of 

limited value to OSHA. OSHA is 

providing an overview of its legal 

requirements for setting standards in 

order to help commenters responding to 

this RFI to provide suggestions that can 

satisfy these requirements. This section 

summarizes OSHA’s legal requirements, 

which are discussed in greater detail in 

Appendix A. The next section provides 

an overview of OSHA’s previous 

attempts to update the PELs. 

Section 6(b) of the OSH Act (Ex. #9) 

provides OSHA with the authority to 

promulgate health standards. It specifies 

procedures that OSHA must use to 

promulgate, modify, or revoke its 

standards, including publishing the 

proposed rule in the Federal Register, 

providing interested persons an 

opportunity to comment, and holding a 

public hearing upon request. However, 

much of the labor and analysis that goes 

into the final rule starts before the 

publication of the proposal. Section 

6(b)(5) of the Act specifies: 

The Secretary, in promulgating standards 

dealing with toxic materials or harmful 

physical agents under this subsection, shall 

set the standard which most adequately 

assures, to the extent feasible, on the basis of 

the best available evidence, that no employee 

will suffer material impairment of health or 

functional capacity even if such employee 

has regular exposure to the hazard dealt with 

by such standard for the period of his 

working life. Development of standards 

under this subsection shall be based upon 

research, demonstrations, experiments, and 

such other information as may be 

appropriate. In addition to the attainment of 

the highest degree of health and safety 

protection for the employee, other 

considerations shall be the latest available 

scientific data in the field, the feasibility of 

the standards, and experience gained under 

this and other health and safety laws. 

Whenever practicable, the standard 

promulgated shall be expressed in terms of 

objective criteria and of the performance 

desired. 

In general, as this provision has been 

construed by the courts, any workplace 

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Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 61387 

health standard adopted by OSHA must 

meet the following requirements: 

(1) The standard must substantially 

reduce a significant risk of material 

harm. 

(2) Compliance with the standard 

must be technically feasible. This means 

that the protective measures required by 

the standard currently exist, can be 

brought into existence with available 

technology, or can be created with 

technology that can reasonably be 

developed. 

(3) Compliance with the standard 

must be economically feasible. This 

means that the standard will not 

threaten the industry’s long term 

profitability or substantially alter its 

competitive structure. 

(4) It must reduce risk of adverse 

health to workers to the extent feasible. 

(5) The standard must be supported 

by substantial evidence in the record, 

consistent with prior agency practice or 

is supported by some justification for 

departing from that practice. 

The significant risk, economic and 

technological feasibility, and substantial 

evidence requirements are of particular 

relevance in setting PELs, and are 

discussed further below. 

A. Significant Risk of a Material 

Impairment: The Benzene Case 

The significant risk requirement was 

first articulated in a plurality decision of 

the Supreme Court in Industrial Union 

Department, AFL–CIO v. American 

Petroleum Institute, 448 U.S. 607 (1980), 

commonly referred to as the Benzene 

case. The petitioners challenged 

OSHA’s rule lowering the PEL for 

benzene from 10 ppm to 1 ppm. In 

support of the new PEL, OSHA found 

that benzene caused leukemia and that 

the evidence did not show that there 

was a safe threshold exposure level 

below which no excess leukemia would 

occur; OSHA chose the new PEL of 1 

ppm as the lowest feasible exposure 

level. The Benzene Court rejected 

OSHA’s approach, finding that the OSH 

Act only required that employers ensure 

that their workplaces are safe, that is, 

that their workers are not exposed to 

‘‘significant risk[s] of harm.’’ 448 U.S. at 

642 (Ex. #10). The Court also made it 

clear that it is OSHA’s burden to 

establish that a significant risk is 

present at the current standard before 

lowering a PEL, stating that the burden 

of proof is normally on the proponent. 

Thus, the Court held, before 

promulgating a health standard, OSHA 

is required to make a ‘‘threshold finding 

that a place of employment is unsafe— 

in the sense that significant risks are 

present and can be eliminated or 

lessened by a change in practices’’ 

before it can adopt a new standard. Id. 

Although the Court declined to 

establish a set test for determining 

whether a workplace is unsafe, it did 

state that a significant risk was one that 

a reasonable person would consider 

significant and ‘‘take appropriate steps 

to decrease or eliminate.’’ 448 U.S. at 

655. For example, it said, a one in a 

1,000 risk would satisfy the 

requirement. However, this example 

was merely an illustration, not a hard 

line rule. The Court made it clear that 

determining whether a risk was 

‘‘significant’’ was not a ‘‘mathematical 

straitjacket’’ and did not require the 

Agency to calculate the exact 

probability of harm. Id. The 1 ppm PEL 

was vacated because OSHA had not 

made a significant risk finding at the 10 

ppm level. 

Following the Benzene case, OSHA 

has satisfied the significant risk 

requirement by estimating the risk to 

workers subject to a lifetime of exposure 

at various possible exposure levels. 

These estimates have typically been 

based on quantitative risk assessments 

in which OSHA, as a general policy, has 

considered an excess risk of one death 

per 1000 workers over a 45-year 

working lifetime as clearly representing 

a significant risk. However, the Benzene 

case does not require OSHA to use such 

a benchmark. In the past, OSHA has 

stated that a lower risk of death could 

be considered significant. See, e.g., 

Preamble to Formaldehyde Standard, 52 

FR 46168, 46234 (suggesting that risk 

approaching six in a million could be 

viewed as significant). (Ex. #11) 

B. Technological and Economic 

Feasibility 

Under section 6(b)(5) of the Act, a 

standard must protect against significant 

risk, ‘‘to the extent feasible, and 

feasibility is understood to have both 

technological and economic aspects. A 

standard is technologically feasible if ‘‘a 

typical firm will be able to develop and 

install engineering and work practice 

controls that can meet the PEL in most 

operations.’’ United Steelworkers v. 

Marshall, 647 F.2d 1189, 1272 (D.C. Cir. 

1981) (‘‘Lead I’’; Ex. #12). OSHA must 

show the existence of ‘‘technology that 

is either already in use or has been 

conceived and is reasonably capable of 

experimental refinement and 

distribution within the standard’s 

deadlines.’’ Id. Where the Agency 

presents ‘‘substantial evidence that 

companies acting vigorously and in 

good faith can develop the technology,’’ 

the Agency is not bound to the 

technological status quo, and ‘‘can 

require industry to meet PELs never 

attained anywhere.’’ Id. at 1264–65. 

Some courts have required OSHA to 

determine whether a standard is 

technologically feasible on an industryby-industry basis, Color Pigments 

Manufacturers Assoc. v. OSHA, 16 F.3d 

1157, 1162–63 (11th Cir. 1994; Ex. #13); 

AFL–CIO v. OSHA, 965, F.2d 962, 981– 

82 (11th Cir. 1992) (Air Contaminants; 

Ex. #8). However, another court has 

upheld technological feasibility findings 

based on the nature of an activity across 

many industries rather than on an 

industry-by-industry basis, Public 

Citizen Health Research Group v. 

United States Department of Labor, 557 

F.3d 165,178–79 (3d Cir. 2009; Ex. #14). 

With respect to economic feasibility, 

the courts have stated ‘‘A standard is 

feasible if it does not threaten massive 

dislocation to . . . or imperil the 

existence of the industry.’’ Lead I, 647 

F.2d at 1265 (Ex. #12). In order to show 

this, OSHA should ‘‘construct a 

reasonable estimate of compliance costs 

and demonstrate a reasonable likelihood 

that these costs will not threaten the 

existence or competitive structure of an 

industry.’’ Id. at 1266. However, ‘‘[T]he 

court probably cannot expect hard and 

precise estimates of costs. Nevertheless, 

the agency must of course provide a 

reasonable assessment of the likely 

range of costs of its standard, and the 

likely effects of those costs on the 

industry.’’ Id. 

While OSHA is not required to show 

that all companies within an industry 

will be able to bear the burden of 

compliance, at least one court has held 

that OSHA is required to show that the 

rule is economically feasible on an 

industry-by-industry basis. Air 

Contaminants, 965 F.2d at 982, 986. (Ex. 

#8) 

C. The Substantial Evidence Test 

The ‘‘substantial evidence test’’ is 

used by the courts to determine whether 

OSHA has reached its burden of proof 

for policy decisions and factual 

determinations. ‘‘Substantial evidence’’ 

is defined as ‘‘such relevant evidence as 

a reasonable mind might accept as 

adequate to support a conclusion.’’ 

American Textile Mfrs. Inst., Inc. v. 

Donovan, 452 U.S. 490, 522 (1981; Ex. 

#15) (quoting Universal Camera Corp. v. 

NLRB, 340 U.S. 474, 477 (1951); Ex. 

#16). The substantial evidence test does 

not require ‘‘scientific certainty’’ before 

promulgating a health standard (AFL– 

CIO v. American Petroleum Institute, 

448 U.S. 607, 656 (1980); Ex. 10), but 

the test does require OSHA to ‘‘identify 

relevant factual evidence, to explain the 

logic and the policies underlying any 

legislative choice, to state candidly any 

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assumptions on which it relies, and to 

present its reasons for rejecting 

significant contrary evidence and 

argument.’’ Lead I, 647 F.2d. at 1207. 

(Ex. #12) 

III. History of OSHA’s Efforts To 

Establish PELs 

The history of OSHA’s PELs has three 

stages. First, OSHA adopted its current 

PELs in 1971, shortly after coming into 

existence. Second, OSHA attempted to 

update its PELs wholesale in 1989, but 

that effort was rejected by the Eleventh 

Circuit Court of Appeals in 1992. Third, 

OSHA has made subsequent, smaller 

efforts to update certain PELs, but those 

efforts have never come to fruition. This 

history is summarized below, and 

discussed in further detail in Appendix 

A. 

A. Adopting the PELs in 1971 

Under section 6(a), OSHA was 

permitted an initial two-year window 

after the passage of the OSH Act to 

adopt ‘‘any national consensus standard 

and any established Federal standard’’ 

29 U.S.C 655(6)(a). OSHA used this 

authority in 1971 to establish PELs that 

were adopted from federal health 

standards originally set by the 

Department of Labor through the WalshHealy Act, in which approximately 400 

occupational exposure limits were 

selected based on ACGIH’s 1968 list of 

Threshold Limit Values (TLVs). In 

addition, about 25 additional exposure 

limits recommended by the American 

Standards Association (now called the 

American National Standards Institute) 

(ANSI), were adopted as national 

consensus standards. 

These standards were intended to 

provide initial protections for workers 

from what the Congress deemed to be 

the most dangerous workplace threats. 

Congress found it was ‘‘essential that 

such standards be constantly improved 

and replaced as new knowledge and 

techniques are developed.’’ S. Rep. 91– 

1282 at 6. (Ex. #17) However, because 

OSHA has been unable to update the 

PELs, they remain frozen at the levels at 

which they were initially adopted. 

OSHA’s PELs are also largely based on 

acute health effects and do not take into 

consideration newer research regarding 

chronic health effects occurring at lower 

occupational exposures. 

B. The 1989 PELs Update 

In 1989, OSHA published the Air 

Contaminants final rule, which remains 

the Agency’s most significant attempt at 

updating the PELs (54 FR 2332). (Ex. #7) 

Unlike typical substance-specific 

rulemakings, where OSHA develops a 

comprehensive standard, the Air 

Contaminants final rule was only 

intended to update existing PELs or to 

add PELs for substances within 

established boundaries. After extensive 

review of all available sources of 

occupational exposure limits (OELs), 

OSHA selected the ACGIH’s 1987–88 

TLVs as the boundaries for identifying 

the substances that would be included 

in the proposed rule. OSHA proposed 

212 more protective PELs and new PELs 

for 164 substances not previously 

regulated. In general, rather than 

performing a quantitative risk 

assessment for each chemical, the 

agency looked at whether studies 

showed excess effects of concern at 

concentrations lower than allowed 

under the existing standard. Where they 

did, OSHA made a significant risk 

finding and either set a PEL (where 

none existed previously) or lowered the 

existing PEL. These new PELs were 

based on Agency judgment, taking into 

account the existing studies and, as 

appropriate, safety factors. Safety factors 

(also called uncertainty factors) are 

applied to the lowest level an effect is 

seen or to a level where no effects are 

seen to derive a PEL. 

In order to determine whether the Air 

Contaminants rule was feasible, OSHA 

prepared the regulatory impact analysis. 

As part of the analysis, OSHA 

performed an industry survey as well as 

site visits. The survey was the largest 

survey ever conducted by OSHA and 

included responses from 5,700 firms in 

industries believed to use chemicals 

addressed in the scope of the Air 

Contaminants proposal. (Ex. #18) It was 

designed to focus on industry sectors 

that potentially had the highest 

compliance costs, identified through an 

analysis of existing exposure data at the 

four-digit SIC (Standards Industrial 

Classification) code level. OSHA 

analyzed the data collected to determine 

whether the updated PELs were both 

technologically and economically 

feasible for each industry sector 

covered. 

For technological feasibility, OSHA 

found that ‘‘in the overwhelming 

majority of situations where air 

contaminants [were] encountered by 

workers, compliance [could] be 

achieved by applying known 

engineering control methods, and work 

practice improvements.’’ 54 FR at 2789; 

Ex. #7. For economic feasibility, OSHA 

assessed the economic impact of the 

standard on industry profits at the twodigit SIC code level, and found the 

economic impact not to be significant, 

and the new standard therefore 

economically feasible. 

In the Air Contaminants final rule, 

OSHA summarized the health evidence 

for each individual substance, discussed 

over 2,000 studies, reviewed and 

addressed all major comments 

submitted to the record, and provided a 

rationale for each new PEL chosen. 

OSHA estimated that over 21 million 

employees were potentially exposed to 

hazardous substances in the workplace 

and over 4.5 million employees were 

exposed to levels above the applicable 

exposure limits. OSHA projected that 

the final rule would result in a potential 

reduction of over 55,000 lost workdays 

due to illnesses per year and that annual 

compliance with this final rule would 

prevent an average of 683 fatalities 

annually from exposures to hazardous 

substances. 

C. The 1989 PELs Update Is Vacated by 

the Court of Appeals 

The update to the Air Contaminants 

standard generally received widespread 

support from both industry and labor. 

However, there was dissatisfaction on 

the part of some industry 

representatives and union leaders, who 

brought petitions for review challenging 

the standard. For example, some 

industry petitioners argued that OSHA’s 

use of generic findings, the inclusion of 

so many substances in one rulemaking, 

and the allegedly insufficient time 

provided for comment by interested 

parties created a record inadequate to 

support the new set of PELs. In contrast, 

the unions challenged the approach 

used by OSHA to promulgate the 

standard and argued that several PELs 

were not protective enough. The unions 

also asserted that OSHA’s failure to 

include any ancillary provisions, such 

as exposure monitoring and medical 

surveillance, prevented employers from 

ensuring the exposure limits were not 

exceeded, and resulted in lessprotective PELs. 

Although only 23 of the 428 PELs 

were challenged, the court ultimately 

decided to vacate the entire rulemaking, 

finding that ‘‘OSHA [had] not 

sufficiently explained or supported its 

threshold determination that exposure 

to these substances at previous levels 

posed a significant risk of these material 

health impairments or that the new 

standard eliminates or reduces that risk 

to the extent feasible.’’ Air 

Contaminants 965 F.2d at 986–987; Ex. 

#8 

With respect to significant risk, the 

court held that OSHA had failed to 

‘‘explain why the studies mandated a 

particular PEL chosen.’’ Id. at 976. 

Specifically, the court stated that OSHA 

failed to quantify the risk from 

individual substances and merely 

provided conclusory statements that the 

new PEL would reduce a significant risk 

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of material health effects.’’ Id. at 975. 

Further, the court rejected OSHA’s 

argument that it had relied on safety 

factors in setting the new PELs, stating 

that OSHA had not adequately 

supported their use. The court observed 

that ‘‘the difference between the level 

shown by the evidence and the final 

PEL is sometimes substantial.’’ Id. at 

978. It said that OSHA had not 

indicated ‘‘how the existing evidence 

for individual substances was 

inadequate to show the extent of risk for 

these factors’’ and that the agency had 

‘‘failed to explain the method by which 

its safety factors were determined.’’ Id. 

‘‘OSHA may use assumptions but only 

to the extent that those assumptions 

have some basis in reputable scientific 

evidence,’’ the court concluded. Id. at 

978–79. 

The Eleventh Circuit court also 

rejected OSHA’s technological 

feasibility findings. The Agency had 

made these findings mainly at the twodigit SIC level, but also at the three- and 

four- digit level where appropriate given 

the processes involved. The court 

rejected this approach, finding that 

OSHA failed to make industry-specific 

findings or identify the specific 

technologies capable of meeting the 

proposed limit in industry-specific 

operations. Id. at 981. While OSHA had 

identified primary air contaminant 

control methods: Engineering controls, 

administrative controls and work 

practices and personal protective 

equipment, the agency, ‘‘only provided 

a general description of how the generic 

engineering controls might be used in 

the given sector.’’ Id. Though noting that 

OSHA need only provide evidence 

sufficient to justify a ‘‘general 

presumption of feasibility,’’ the court 

held that this ‘‘does not grant OSHA 

license to make overbroad generalities 

as to feasibility or to group large 

categories of industries together without 

some explanation of why findings for 

the group adequately represents the 

different industries in that group.’’ Id. at 

981–82. 

The court rejected OSHA’s economic 

feasibility findings for similar reasons. 

As discussed above, OSHA supported 

its economic feasibility findings for the 

1989 Air Contaminants rule based 

primarily on the results of a survey of 

over 5700 businesses, summarizing the 

projected cost of compliance at the twodigit SIC industry sector level. The court 

held that OSHA was required to show 

that the rule was economically feasible 

on an industry-by industry basis, and 

that OSHA had not shown that its 

analyses at the two-digit SIC industry 

sector level were appropriate to meet 

this burden. Id. at 982. ‘‘[A]verage 

estimates of cost can be extremely 

misleading in assessing the impact of 

particular standards on individual 

industries’’ the court said, and 

‘‘analyzing the economic impact for an 

entire sector could conceal particular 

industries laboring under special 

disabilities and likely to fail as a result 

of enforcement.’’ Id. While OSHA might 

‘‘find and explain that certain impacts 

and standards do apply to entire sectors 

of an industry’’ if ‘‘coupled with a 

showing that there are no 

disproportionately affected industries 

within the group,’’ OSHA had not 

explained why its use of such a ‘‘broad 

grouping was appropriate.’’ Id. at 982 

n.28, 983. 

D. Revising OSHA’s PELs in the Wake of 

the Eleventh Circuit Decision 

In the wake of the Eleventh Circuit’s 

decision, OSHA has generally pursued a 

conservative course in satisfying its 

judicially imposed analytical burdens. 

The set of resulting analytical 

approaches OSHA has engaged in is 

highly resource-intensive and has 

constrained OSHA’s ability to prioritize 

its regulatory efforts based on risk of 

harm to workers. In 1995, OSHA made 

its first attempt following the Air 

Contaminants ruling to update a smaller 

number of PELs using a more rigorous 

analysis of risk, workplace exposures, 

and technological and economic 

feasibility. (Ex. #20) OSHA and the 

National Institute for Occupational 

Safety and Health (NIOSH) conducted 

preliminary research on health risks 

associated with exposure and extent of 

occupational exposure. Sixty priority 

substances were identified for further 

examination and twenty of the sixty 

substances were selected to form a 

priority list. Early in 1996, the Agency 

announced its plans for a stakeholder 

meeting, and identified the twenty 

priority substances, as well as several 

risk-related discussion topics. (Ex. #21) 

During the meeting, almost all 

stakeholders from industry and labor 

agreed that the PELs needed to be 

updated; however, not one group 

completely supported OSHA’s 

suggested approach. Overall, many of 

the stakeholders did not support the 

development of a list of priority 

chemicals targeted for potential 

regulation and felt there was a lack of 

transparency in the process for selecting 

the initial chemicals. 

In response to stakeholder input and 

OSHA’s research, the agency selected 

seven of the 20 substances discussed at 

the stakeholder meeting for detailed 

analysis of risks and feasibility. The 

chemicals selected were: (i) 

Glutaraldehyde, (ii) carbon disulfide, 

(iii) hydrazine, (iv) perchloroethylene, 

(v) manganese, (vi) trimellitic 

anhydride, and (vii) chloroprene. 

Quantitative risk assessments were 

performed in-house, and research 

(including site visits) was undertaken to 

collect detailed data on uses, worker 

exposures, exposure control technology 

effectiveness, and economic 

characteristics of affected industries. 

The research and analysis were 

carried out over several years, after 

which OSHA decided not to proceed 

with rulemaking. (Ex. #22) This 

decision was influenced by findings that 

(i) prevalence and intensity of worker 

exposures for some of the substances 

(e.g., carbon disulfide and hydrazine) 

had declined substantially since the 

1989 rule was promulgated; (ii) industry 

had voluntarily implemented controls to 

reduce the exposure to safe levels; and 

(iii) for others, substantial Agency 

resources would have been required to 

fully assess technological and economic 

impacts. 

In 1997, OSHA held another meeting 

with industry and labor on the proposed 

PEL development process. Although the 

project did not result in a rulemaking to 

revise the PELs, OSHA gained valuable 

experience in developing useful 

approaches for quantifying non-cancer 

health risks through collaboration with 

external reviewers in scientific peer 

reviews of its risk analyses. OSHA is 

now examining ways to better address 

chemical exposures given current 

resource constraints and regulatory 

limitations. 

For readers who are interested in a 

more detailed account of the legislation 

and court decisions that shaped OSHA’s 

current regulatory framework, Appendix 

A to this Request for Information, 

History, Legal Background and 

Significant Court Decisions, provides 

additional information. Readers may 

want to consult Appendix A as they 

frame responses to the questions posed 

in this Request for Information. 

IV. Reconsideration of Current 

Rulemaking Processes 

As reviewed in Section II (Legal 

Requirements for OSHA Standards) and 

Section III (History of OSHA’s Efforts to 

Establish PELs), OSHA has to use the 

best available evidence to make findings 

of significant risk, substantial 

reductions in risk, and technological 

and economic feasibility under the Act. 

This section reviews how interpretation 

of 6(b)(5) and subsequent case law has 

resulted in the methods it uses when 

developing risk, technical feasibility, 

and economic findings as well as the 

evidence OSHA has used in the past to 

make these findings (i.e., OSHA’s use of 

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formal risk assessment modeling to 

evaluate significant risk, and the 

Agency’s use of worker exposure data 

and exposure control effectiveness data 

to evaluate technical feasibility and 

costs of compliance). 

This section also reviews 

developments in science and technology 

and how these new advancements may 

improve the scientific basis for making 

findings of significant risk, technical 

feasibility, and economic feasibility. As 

an example, the National Academies of 

Science has released extensive reviews 

of advances in science, toxicology, and 

risk and exposure assessment and 

evaluated how the Federal government 

can potentially utilize these 

advancements in its decision-making 

processes (NRC, 2012; Ex. #23, NRC, 

2009; Ex. #24, NRC, 2007; Ex. #25). 

While new technologies will advance 

the public’s understanding in these 

critical areas, the Agency has 

obligations under the OSH Act to make 

certain findings under 6(b)(5), as 

discussed above in Section III. How 

OSHA might utilize these new 

developments to meet the Agency’s 

evidentiary burden will be discussed in 

this section. 

A. Considerations for Risk Assessment 

Methods 

1. Current Quantitative Risk Assessment 

Methods Typically Used by OSHA To 

Support 6(b) Single Substance 

Rulemaking 

As discussed in Section III, the 

Supreme Court requires OSHA to 

determine that a significant risk exists 

before adopting an occupational safety 

and health standard. While the Court 

did not stipulate a means to distinguish 

significant from insignificant risks, it 

broadly described the range of risks 

OSHA might determine to be 

significant: 

It is the Agency’s responsibility to 

determine in the first instance what it 

considers to be a ‘‘significant’’ risk. Some 

risks are plainly acceptable and others are 

plainly unacceptable. If, for example, the 

odds are one in a billion that a person will 

die from cancer by taking a drink of 

chlorinated water, the risk clearly could not 

be considered significant. On the other hand, 

if the odds are one in a thousand that regular 

inhalation of gasoline vapors that are 2 

percent benzene will be fatal, a reasonable 

person might well consider the risk 

significant and take the appropriate steps to 

decrease or eliminate it. (Benzene, 448 U.S. 

at 655). (Ex. #10), 

OSHA has interpreted the Court’s 

example to mean that a 1 in 1000 risk 

of serious illness is significant, and has 

used this measure to guide its 

significance of risk determinations. For 

example, OSHA’s risk assessment for 

hexavalent chromium estimated that a 

45-year occupational exposure at the 

PEL of 5mg/m3 would lead to more than 

10 lung cancer cases per 1000 workers 

exposed. Because this risk exceeds the 

value of one case of lung cancer per 

1000 exposed workers, OSHA found it 

to be significant. The significance of risk 

determinations of other rules since the 

Benzene decision have typically 

followed a similar logic. 

Over the three decades since the 

Benzene decision, OSHA has gradually 

built up a highly rigorous approach to 

derive quantitative estimates of risk 

such as those found in the hexavalent 

chromium preamble. First, the Agency 

reviews the available exposure-response 

data for a chemical of interest. It 

evaluates the available data sets and 

identifies those best suited for 

quantitative analysis. Using the best 

available data, the Agency then 

conducts extensive statistical analyses 

to develop an exposure-response model 

that is able to extrapolate probability of 

disease at exposures below the observed 

data. Once the model is developed, 

OSHA conducts further analyses to 

evaluate the sensitivity of the model to 

error and uncertainties in the modeling 

inputs and approach. The exposureresponse model is used to generate 

estimates of risk associated with a 

working lifetime of occupational 

exposure to the chemical of interest over 

a range of PEL options that often 

include exposure levels below those 

considered to be technologically 

feasible. The entire risk assessment has 

always been subject to peer review, from 

choice of data set(s) through generation 

of lifetime risk estimates.When the 

proposed rule is released for comment, 

it receives additional scrutiny from the 

scientific community, stakeholders, and 

the general public. The Agency uses the 

feedback of the peer review panel and 

public comment at the time of proposal 

to further test and develop the risk 

analysis. 

This model-based approach to risk 

assessment has a number of important 

advantages. The quantitative risk 

estimates can be easily compared with 

the level of 1 in 1000 that the Court 

cited as an example of significant risk. 

Sometimes, the best available data come 

from worker or animal populations with 

exposure levels far above the 

technologically feasible levels for which 

OSHA must evaluate risk, and a risk 

model is used to extrapolate from high 

to low exposures. When large, highquality exposure-response data sets are 

available, a rigorous quantitative 

analysis can yield robust and fairly 

precise risk estimates to inform public 

understanding and debate about the 

health benefits of a new or revised 

regulation. However, there are also 

drawbacks to the model-based 

approach, and there are situations 

where a modeling analysis may not be 

necessary or appropriate for OSHA to 

make the significance of risk 

determination to support a new or 

revised regulation. Model-based risk 

analyses tend to require a great deal of 

Agency time and resources. 

In some cases, the model-based 

approach is essential to OSHA’s 

significant risk determination, because 

it is not evident prior to a modeling 

analysis whether there is significant risk 

at current and technologically-feasible 

exposures. In other cases, however, it 

may be evident from the scientific 

literature or other readily available 

evidence that risk at the existing PEL is 

clearly significant and that it can be 

substantially reduced by a more 

stringent regulation without the need for 

quantitative estimates extrapolated from 

an exposure-response model. In 

addition to reducing significant risk of 

harm, the OSH Act also directs the 

Agency to determine that health 

standards for toxic chemicals are 

feasible. At times, it is evident without 

extensive analysis that the most 

stringent PEL feasible can only reduce, 

not eliminate, significant risk. In such 

cases, the value of a model-based 

quantitative risk assessment may not 

warrant the Agency time and resources 

that model-based risk assessment 

requires. 

In situations described above where 

the PEL may be set at the lowest feasible 

level, OSHA believes that it can 

establish significant risk more 

efficiently instead of relying on 

probabilistic estimates from doseresponse modeling as described above. 

OSHA is exploring a number of more 

flexible, scientifically accepted 

approaches that may streamline the risk 

assessment process and increase the 

capacity to address a greater number of 

chemicals. 

Question IV.A.1: OSHA seeks input 

on the risk assessment process 

described above. When is a model-based 

analysis necessary or appropriate to 

determine significance of risk and to 

select a new or revised PEL? When 

should simpler approaches be 

employed? Are there specific 

approaches OSHA should consider 

using when a model-based analysis is 

not required? To the extent possible, 

please provide detailed explanation and 

examples of situations when a modelbased risk analysis is or is not necessary 

to determine significance of risk and to 

develop a new standard. 

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2. Proposed Tiered Approach to Risk 

Assessment in Support of Updating 

PELs for Chemical Substances 

a. General Description and Rationale of 

Tiered Approach 

OSHA is considering a tiered process 

to exposure-response assessment that 

may enable the agency to more 

efficiently make the significant risk 

findings needed to establish acceptable 

PELs for larger numbers of workplace 

chemicals. The approach involves three 

stages: dose-response analysis in the 

observed range, margin of exposure 

determination, and exposure-response 

extrapolation (if needed). The process 

overlaps with the risk-based 

methodologies employed by EPA IRIS, 

NIOSH, the Agency for Toxic 

Substances Disease Registry (ATSDR), 

the European Union Registration, 

Evaluation, Authorization, and 

Restriction of Chemicals (REACH) 

program, and other organizations that 

recommend chemical toxicity values or 

exposure levels protective of human 

health. The first step is dose-response 

analysis in the observed range. During 

this step, OSHA analyzes exposures (or 

doses) and adverse outcomes from 

human studies or animal bioassays, 

particularly at the lower end of the 

exposure range. This involves the 

derivation of a ‘‘low-end toxicity 

exposure’’ (LETE), which is discussed 

further in section IV.A.2.c. below. 

The second step is margin of exposure 

determination, where LETEs are 

compared with the range of possible 

exposure limits that OSHA believes to 

be feasible for the new or proposed 

standard. Typically, there is a close and 

ongoing dialogue between those OSHA 

technical staff and management 

responsible for the risk assessment and 

their counterparts responsible for the 

feasibility analyses as the separate 

determinations are being 

simultaneously developed. Feasibility 

analyses, in particular, can take years of 

research, including site visits and 

industry surveys. In many of OSHA’s 

rulemakings, the lowest feasible PEL 

can only reduce, not eliminate, 

significant risk. Thus, OSHA sets many 

PELs at the lowest feasible level, and 

not at a level of occupational exposure 

considered to be without significant 

risk. This significant risk orientation 

differs from other Federal Agencies, 

such as EPA and ATSDR that set 

environmental exposure levels 

determined to be health protective 

without consideration of feasibility. 

OSHA is considering using a margin 

of exposure (MOE) approach to compare 

the LETE with the range of feasible 

exposure limits. If the MOE indicates 

the range of feasible exposures is in 

close proximity to the exposures where 

toxicity is observed (i.e., a low MOE) 

then it may not be necessary to 

extrapolate exposure-response below 

the observed range in order to establish 

significant risk. In this situation, OSHA 

would set the PEL at the exposure level 

it determines to be feasible and the 

dose-response analysis in the observed 

range should be sufficient to support 

Agency significant risk findings. The 

PEL is set at the lowest feasible level, 

with the understanding that significant 

risk of adverse health outcomes remains 

at the new PEL. In the traditional risk 

assessment approach described 

previously, OSHA uses quantitative 

exposure-response modeling to estimate 

risks below the range of observed 

exposure, without regard to whether 

such exposures are considered to be 

technologically feasible. If the lowest 

technologically feasible workplace 

exposures are determined to be far 

below the LETE (i.e., a high MOE), an 

exposure-response model would be 

needed to determine significant risk at 

exposures below the observed range and 

to set the appropriate PEL. 

If there is a high MOE, then the 

Agency would move onto the final stage 

of the tiered approach, which is 

exposure-response extrapolation, where 

the dose-response relationship is 

extrapolated outside the observed range. 

Many regulatory agencies, such as EPA, 

choose to extrapolate outside the 

observed range for non-cancer health 

outcomes by applying a series of 

extrapolation factors, also called 

uncertainty factors, to an observed lowend toxicity value, referred to as a point 

of departure (POD). The POD is very 

similar to the LETE described above. 

The distinction between these toxicity 

values is discussed later in the 

subsection. The extrapolation factors are 

further explained below. 

In many instances, EPA does not use 

the extrapolation factor approach for 

cancer effects. Rather, EPA uses doseresponse modeling in the observed 

range and a linear extrapolation below 

the observed range to derive a unit risk 

(i.e., risk per unit of exposure). As 

described previously, OSHA also uses 

dose-response modeling to extrapolate 

risk below the observed range for 

carcinogens as was done for hexavalent 

chromium (71 FR 10174–10221; Ex. 

#26) and methylene chloride (62 FR 

1516–1560; Ex. #27). There is a 

reasonable body of scientific evidence 

that genotoxic carcinogens, and perhaps 

other carcinogenic modes of action, 

display linear, non-threshold behavior 

at very low dose levels. OSHA also uses 

dose-response modeling to extrapolate 

risk below the observed range for 

carcinogens. As mentioned earlier, the 

Agency develops appropriate exposureresponse models (linear or non-linear) 

that best fit the existing data and are 

consistent with available information on 

mode of action. The models can be used 

to extrapolate risk associated with a 

working lifetime at occupational 

exposures below the observed range. 

In some situations, the LETE is further 

adjusted to calculate worker equivalent 

exposures and to account for how the 

chemical is absorbed, distributed, and 

metabolized, and interacts with target 

tissues in the body. These features and 

other important issues related to the 

tiered approach to exposure-response 

assessment are discussed below. OSHA 

believes that there are a number of 

potential advantages to using a tiered 

risk assessment framework including 

opportunities to rely more heavily on 

peer-reviewed risk assessments already 

prepared by other Federal agencies. 

b. Hazard Identification and DoseResponse Analysis in the Observed 

Range 

Hazard identification is the first step 

in the Federal risk assessment 

framework as laid out by the National 

Research Council’s ‘red book’ in 1983 

(NRC, 1983; Ex. #28). In conducting a 

hazard identification, OSHA evaluates 

individual study quality and determines 

the weight of evidence from 

epidemiological, experimental, and 

supporting data. Study quality favors 

strong methodology, characterization of 

exposure during critical periods, 

adequate sample size/statistical power, 

and relevance to the workplace 

population. OSHA gives weight to both 

positive and negative studies according 

to study quality when the Agency 

evaluates the association between 

chemical agent and an adverse health 

effect. OSHA determines causality based 

on criteria developed by Bradford Hill 

(Hill, 1965; Ex. #29, Rothman & 

Greenland, 1998; Ex. #30). In its review 

of the available evidence, OSHA 

assesses the chemical’s modes of action 

(MOA) and the key molecular, 

biological, pathological, and clinical 

endpoints that contribute to the health 

effects of concern. 

The Mode of Action (MOA) is a 

sequence of key events and processes 

starting with the interaction of the agent 

with a molecular or cellular target(s) 

and proceeding through operational and 

anatomical changes that result in an 

adverse health effect(s) of concern. The 

key events are empirically measurable 

molecular or pathological endpoints and 

outcomes in experimental systems. 

These represent necessary precursor 

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steps or biologically-based markers 

along the progression to frank illness 

and injury. 

MOA informs selection of appropriate 

toxicity-related endpoints and models 

for dose-response analysis. OSHA then 

conducts a dose-response analysis for 

critical health effects determined to be 

associated with a chemical, provided 

there are suitable data available. Doseresponse analysis requires quantitative 

measures of both exposure and toxicityrelated endpoints. OSHA gives 

preference to studies with relevant 

occupational routes that display a welldefined dose-related change in response 

with adequate power to detect effects at 

the exposure levels of interest. The 

Agency generally prefers high quality 

epidemiologic studies for dose-response 

analysis over experimental animal 

models, provided there is adequate 

exposure information and confounding 

factors are appropriately controlled. 

OSHA may only adopt standards for 

exposure to ‘‘toxic materials and 

harmful physical agents’’ that causes 

‘‘material impairment of health and loss 

of functional capacity even if such 

employee has regular exposure to the 

hazard dealt with by such standard for 

the period of his working life.’’ OSH Act 

§ 6(b)(5) (Ex. #9) Therefore, its doseresponse analysis considers those 

biological endpoints and health 

outcomes that can lead to adverse 

physiological or clinical harm caused by 

continued exposure over a working 

lifetime. This includes key molecular 

and cellular biomarkers established as 

necessary precursor events along a 

critical disease pathway. It is important 

that the toxicity-related endpoints 

observed in experimental animals 

selected for dose-response analysis have 

relevance to humans and are not unique 

to the test species. 

In the past, OSHA, for the most part, 

has undertaken an independent 

evaluation of the evidence in its 

identification of hazards and selection 

of critical studies and toxicity-related 

endpoints for dose-response analysis. 

However, other Federal agencies use the 

same risk assessment framework with 

similar hazard identification and doseresponse selection procedures. EPA, 

ATSDR, NIOSH and others have active 

risk assessment programs and have 

recently evaluated many chemicals of 

interest to OSHA. These assessments 

undergo scientific peer review and are 

subject to public comment. The Agency 

is considering ways to reduce the time 

and resources needed to independently 

evaluate the available study data by 

placing greater reliance on the efforts of 

other credible scientific organizations. 

Although some organizations use their 

study evaluations to support nonoccupational risk assessments, OSHA 

believes that, in most cases, these 

evaluations can be adapted to the 

occupational context. 

Question IV.A.2: If there is no OSHA 

PEL for a particular substance used in 

your facility, does your company/firm 

develop and/or use internal 

occupational exposure limits (OELs)? If 

so, what is the basis and process for 

establishing the OEL? Do you use an 

authoritative source, or do you conduct 

a risk assessment? If so, what sources 

and risk assessment approaches are 

applied? What criteria do facilities/firms 

consider when deciding which 

authoritative source to use? For 

example, is rigorous scientific peer 

review of the OEL an important factor? 

Is transparency of how the OEL was 

developed important? 

Question IV.A.3: OSHA is considering 

greater reliance on peer-reviewed 

toxicological evaluations by other 

Federal agencies, such as NIOSH, EPA, 

ATSDR, NIEHS and NTP for hazard 

identification and dose-response 

analysis in the observed range. What 

advantages and disadvantages would 

result from this approach and could it 

be used in support of the PEL update 

process? 

c. Derivation of Low-End Toxicity 

Exposure (LETE) 

An important aspect of the doseresponse analysis is the determination 

of exposures that can result in adverse 

outcomes of interest. For most studies, 

response rates ranging from 1 to 10 

percent represent the low end of the 

observed range. Epidemiologic studies 

generally are larger and can show a 

lower observed response rate than 

animal studies, which typically have 

fewer test subjects. EPA, ATSDR and EU 

REACH also derive an estimated dose at 

the low end of the observed range (i.e., 

LETE) as part of their dose-response 

assessments. This dose is referred to as 

the POD (‘point of departure’) because it 

is used as a starting point for low dose 

extrapolation or the application of 

uncertainty factors as described above to 

derive toxicity values. EPA, ATSDR and 

EU REACH use the POD/extrapolation 

factor approach to determine Reference 

Concentrations (RfC), Minimal Risk 

Levels (MRL) and Derived No Effect 

Levels (DNELs), respectively. OSHA 

believes the LETE is an exposure where 

studies may have demonstrated 

significant risk. However, OSHA does 

not intend to use the LETE as the point 

of extrapolation for determining a ‘‘safe’’ 

exposure level in the manner used by 

the aforementioned agencies. OSHA 

may use the LETE in calculating an 

MOE to evaluate the need for low dose 

extrapolation as described in the next 

section. 

Traditionally, either the Lowest 

Observed Adverse Effect Level (LOAEL) 

or No Observed Adverse Effect Levels 

(NOAEL) has served as easily obtainable 

LETE descriptors. More recently, the 

Benchmark Dose (BMD) methodology 

has increasingly been applied to derive 

an LETE. The BMD approach uses a 

standard set of empirical models to 

determine the dose associated with a 

pre-selected benchmark response (BMR) 

level. An example is the dose associated 

with a 10 percent incidence (i.e., 

BMD10) and the statistical lower 

confidence limit (i.e., BMDL10). 

Selection of an appropriate BMR 

considers biologic as well as statistical 

factors and a lower BMR is typically 

applied for clinically serious outcomes 

(e.g., lung or heart disease) than for less 

serious adverse effects (e.g., preclinical 

loss of neurological or pulmonary 

function). In some cases, more 

sophisticated models can be used in the 

LETE determination, based on 

physiologically-based toxicokinetics, 

toxicodynamics, or dosimetry models 

that relate the administered dose to a 

more toxicologically relevant dose 

metric at a biological target site, if 

sufficient data is available and the 

models are appropriately validated. This 

is discussed further below. 

Question IV.A.4: OSHA is considering 

using the Point of Departure (POD) (e.g., 

BMD, LOAEL, NOAEL), commonly 

employed by other authoritative 

organizations for carrying out noncancer risk assessments as a suitable 

descriptor of the Low End Toxicity 

Exposure (LETE) level that represents a 

significant risk of harm. Is this an 

appropriate application of the POD by 

OSHA? Are there other exposure values 

that OSHA should consider for its 

LETE? 

In many situations, the LETE must be 

adjusted to represent a typical worker 

exposure. The most common 

adjustments are to correct for the 

standard occupational exposure 

conditions of eight hours a day/five 

days a week and/or respiratory volume 

during work activity. OSHA and NIOSH 

have used a standard ventilation rate of 

10 m3 of air per 8-hour work shift for 

a typical worker undergoing light 

physical work activity. 

Allometric scaling (i.e., BW3/4) is 

recommended by some Federal 

authorities when scaling animal doses 

to human equivalents to account for 

toxicokinetic differences in rates of 

absorption, metabolism, and excretion 

when more specific data is lacking. 

Allometric scaling refers to scaling 

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physiological rates and quantities to 

mass or volume of one animal species 

to another animal species. The 

relationship is generally dependent on 

body weight (BW), often in the form of 

y=BWa where y is the physiological 

measure and a is the scaling 

component. Many physiological and 

biochemical processes (such as heart 

rate, basal metabolic rate, and 

respiration rate have been found to have 

a scaling component of 0.75. 

Allometric scaling is most applicable 

when the toxicologically relevant dose 

is a parent compound or stable 

metabolite whose absorption rate and 

clearance from the target site is 

controlled primarily by first order 

processes. Allometric scaling is less 

well suited for portal-of-entry effects or 

when toxicity is a consequence of a 

highly reactive compound or metabolite. 

Portal of entry refers to the tissue or 

organ of first contact between the 

biological system and the agent. This is 

nasal, respiratory tract and pulmonary 

tissues for inhalation; skin for dermal 

contact, and mouth and digestive tract 

for oral exposure. 

In the case of respiratory tract effects 

from inhalation, EPA recommends 

adjusting inhalation doses based on 

generic dosimetry modeling that 

depends on the form of the chemical 

(e.g., particle of gas) and site of toxicity 

(e.g., portal of entry or systemic) (EPA, 

1994; Ex. #31). For example, the human 

equivalent for a reactive gas that exerts 

its toxic effect on the respiratory tract is 

scaled based on animal to human 

differences in ventilation rate and 

regional surface area of the respiratory 

tract. On the other hand, the dosimetry 

model adjustment for an insoluble gas 

that exerts its effect in a tissue remote 

from the lung is scaled by species 

differences in the blood: gas partition 

coefficient. The generic dosimetry 

models can accommodate specific 

chemical data, if available. The models 

are only intended to account for humanto-animal differences in bioavailability 

and further allometric or extrapolation 

factors may be needed to account for 

species differences in metabolic 

activation and toxicodynamics (i.e., 

target site sensitivity to an equivalent 

delivered dose). 

Question IV.A.5: Several 

methodologies have been utilized to 

adjust critical study exposures to a 

worker equivalent under representative 

occupational exposure conditions 

including standard ventilation rates, 

allometric scaling, and toxicokinetic 

modeling. What are reasonable and 

acceptable methods to determine worker 

equivalent exposure concentrations, 

especially from studies in animals or 

other experimental systems? 

The worker-adjusted LETE that is 

derived from dose-response analysis in 

the observed range should be regarded 

as a chemical exposure level that leads 

to significant risk of harm. In most 

cases, the LETE is expected to elicit a 

toxic response in 1 to 10 percent of the 

worker population. This approximates 

an excess risk of 10 to 100 cases of 

impairment per 1000 exposed workers 

over a duration that is typically less 

than a 45-year working life. This degree 

of risk would exceed the 1 per 1000 

probability that OSHA historically 

regards as a clearly significant risk. 

d. Margin of Exposure (MOE) as a 

Decision Tool for Low Dose 

Extrapolation 

As discussed previously, OSHA’s 

statutory and legal obligations dictate 

that PELs be set at the level that 

eliminates significant risk, if feasible, or 

if not, at the lowest feasible level. 

Therefore, Agency risk assessments are 

directed at determining significant risk 

at these feasible exposures. Because of 

the feasibility constraints, low dose 

extrapolation is not always needed to 

make the required risk findings. The 

OSHA significant risk orientation differs 

from other Federal Agencies, such as 

EPA and ATSDR. The risk-based EPA 

RfCs and ATSDR MRLs are intended as 

environmental exposure levels 

determined to be health protective 

without consideration of feasibility. 

NIOSH also develops workplace 

exposure limits. These recommended 

exposure limits (RELs) are based on risk 

evaluations using human or animal 

health effects data. The exposure levels 

that can be achieved by engineering 

controls and measured by analytical 

techniques are considered in the 

development of RELs, but the 

recommended levels are often below 

what OSHA regards as technologically 

feasible. 

A MOE approach can assist in 

determining the need to extrapolate risk 

below the observed range. The 

appropriate MOE for use as a decision 

tool for low dose extrapolation is the 

LETE divided by an estimate of the 

lowest technologically feasible exposure 

(LTFE). A large MOE (i.e., LETE/LTFE 

ratio) means the LTFE is considerably 

below exposures observed to cause 

adverse outcomes along a critical 

toxicity pathway. This situation would 

require low-dose risk extrapolation to 

determine whether technologically 

feasible exposures lead to significant 

risk. A small MOE means the LTFE 

estimate is reasonably close to the 

observed toxic exposures indicating the 

LTFE likely leads to significant risk of 

harm. In this situation, OSHA would set 

the PEL at the exposure level it 

determines to be feasible and the doseresponse analysis in the observed range 

should be sufficient to support Agency 

significant risk findings. 

There are several factors that OSHA 

would need to consider in order to find 

that the MOE is adequate to avoid lowdose risk extrapolation. These include 

the nature of the adverse outcome, the 

magnitude of the effect, the 

methodological designs and 

experimental models of the selected 

studies, the exposure metric associated 

with the outcome, and the exposure 

period over which the outcome was 

studied. OSHA may regard a larger MOE 

as acceptable to avoid the need for lowdose extrapolation for serious clinical 

effects than a less serious subclinical 

outcome. A larger MOE may also be 

found acceptable for irreversible health 

outcomes that continue to progress with 

continued exposure and respond poorly 

to treatment than reversible health 

outcomes that do not progress with 

further exposure. Health outcomes that 

relate to cumulative exposures would 

tolerate higher MOEs than similar 

outcomes unrelated to cumulative 

exposure, especially in short-term 

studies. In some instances, an adverse 

outcome observed in experimental 

animals would tolerate higher MOEs 

than the same response in a human 

study that more closely resembles the 

occupational situation. 

Other Federal agencies apply the 

MOE approach as part of the risk 

assessment process. EPA has included 

MOE calculations in risk 

characterizations of environmental 

exposure scenarios to assist in risk 

management decisions (EPA, 2005; Ex. 

#32). The EU has also applied a very 

similar Margin of Safety analysis to 

characterize results of risk assessment 

conclusions (ECB, 2003; Ex. #33). In its 

report on the appropriate uses of risk 

assessment and risk management in 

federal regulatory programs, the 

Presidential Commission on Risk 

Assessment and Risk Management 

recommended MOE as an approach that 

provides a common metric for 

comparing health risks across different 

toxicities and public health programs 

(PCRARM, 1997; Ex. #34). 

Question IV.A.6: OSHA is considering 

a Margin of Exposure approach that 

compares the LETE with the Lowest 

Technologically Feasible Exposure 

(LTFE) as a decision tool for low dose 

extrapolation. Is this a reasonable means 

of determining if further low dose 

extrapolation methods are needed to 

meet agency significant risk findings? 

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What other approaches should be 

considered? 

e. Extrapolation Below the Observed 

Range 

The last step in the tiered approach is 

extrapolation of risk below the observed 

range. This low-dose extrapolation 

would only be needed if the MOE is 

sufficiently high to warrant further 

dose-response analysis. This situation 

occurs when technologically feasible 

exposures are far below the LETE and 

quantitative estimates of risk could be 

highly informative in the determination 

of significant risk. As described in 

subsection A.1, OSHA has historically 

used probabilistic risk modeling to 

quantitatively estimate risks at exposure 

levels below the observed range. 

Depending on the nature of the 

exposure-response data, the Agency has 

relied on a wide range of different 

models that have included linear 

relative risk (e.g., hexavalent chromium/ 

lung cancer), logistic regression (e.g., 

cadmium/kidney dysfunction), and 

physiologically-based pharmacokinetic 

(e.g., methylene chloride/cancer) 

approaches. 

Probabilistic risk models can require 

considerable time and resources to 

construct, parameterize, and statistically 

verify against appropriate study data, 

especially for a large number of 

chemical substances. As mentioned 

previously, several government 

authorities responsible for managing the 

risk to human populations posed by 

hazardous chemicals commonly use the 

computationally less complex 

uncertainty factor approach to 

extrapolate dose-response below the 

observed range. The uncertainty factors 

account for variability in response 

within the human population, 

uncertainty with regard to the 

differences between experimental 

animals and humans, and uncertainty 

associated with various other data 

inferences made in the assessment. For 

each of these considerations, a 

numerical value is assigned and the 

point of departure is divided by the 

product of all applied uncertainty 

factors. The result is an exposure level 

considered to be without appreciable 

risk. OSHA attempted to apply 

uncertainty factors in the 1989 Air 

Contaminants Rule to ensure that new 

PELs were set at levels that were 

sufficiently below exposures observed 

to cause health effects. The Eleventh 

Circuit ruled that OSHA had failed to 

show how uncertainty factors addressed 

the extent of risk posed by individual 

substances and that similarly, OSHA 

failed to explain the method it used to 

derive the safety factors. Air 

Contaminants 965 F.2d at 978.( Ex. #8) 

Since the court ruling, the uncertainty 

factor approach has undergone 

considerable refinement. The scientific 

considerations for applying individual 

factors have been carefully articulated 

by EPA and other scientific authorities 

in various guidance materials (EPA, 

2002; Ex. #35, IPCS, 2005; Ex. #36, 

ECHA, 2012a; Ex. #37). For some factors 

under certain circumstances, it is being 

proposed that standard ‘default’ values 

can be replaced with ‘data-driven’ 

values (EPA, 2011; Ex. #38). However, 

the type and magnitude of the 

uncertainty factor employed for any 

individual substance still requires a 

degree of scientific judgment. The 

methodology does not provide 

quantitative exposure-specific estimates 

of risk, such as one in a thousand, that 

can readily be compared to the 

significant risk probabilities discussed 

in the Benzene decision. 

The National Research Council’s 

Science and Decisions report recently 

advocated a dose-response framework 

that provides quantitative risk estimates 

by applying distributions instead of 

‘single value’ factors (NRC, 2009; Ex. 

#24). The critical extrapolation factors, 

such as species differences in toxic 

response at equivalent target doses and 

inter-individual variability in the 

human population are defined by 

lognormal distribution with an 

estimated standard deviation. This 

allows the human equivalent LETE to be 

derived in terms of a median and 

statistical lower confidence bound. The 

distributional nature of the analysis 

facilitates extrapolation in terms of a 

probabilistic projection of average and 

upper bound risk at specific exposures, 

such as X number of individuals 

projected to develop disease out of 1000 

workers exposed to Z level of a toxic 

substance within some confidence level 

Y. The NRC report describes several 

different conceptual models with case 

examples and extrapolation factor 

distribution calculations (NRC, 2009; 

Ex. #24). 

Question IV.A.7: Can the uncertainty 

factor methodology for extrapolating 

below the observed range for non-cancer 

effects be successfully adapted by 

OSHA to streamline its risk assessment 

process for the purpose of setting 

updated PELs? Why or why not? Are 

there advantages and disadvantages to 

applying extrapolation factor 

distributions rather than single 

uncertainty factor values? Please 

explain your reasoning. 

3. Chemical Grouping for Risk 

Assessment 

OSHA is also considering the use of 

one or more chemical grouping 

approaches to expedite the risk 

assessment process. In certain cases, it 

may be appropriate to extrapolate data 

about one chemical across a group or 

category of similar chemicals. These 

approaches are discussed below. 

a. Background on Chemical Grouping 

The term ‘grouping’ or ‘chemical 

grouping’ describes the general 

approach to assessing more than one 

chemical at the same time. It can 

include formation of a chemical 

category or identification of a chemical 

analogue (OECD, 2007; Ex. #39). 

Chemical categories or analogues can be 

based on the structural relationship 

between the chemicals being grouped. 

Structure-activity relationships (SAR) 

are relationships between a compound’s 

chemical structure and physicochemical 

properties and its biological effects (e.g., 

cancer) on living systems. Structurally 

diverse chemicals can sometimes be 

grouped for risk analysis based on a 

common mechanism/mode of action or 

metabolic activation pathway (i.e., 

mechanism/mode of action clustering). 

Endpoint information for one chemical 

is used to predict the same endpoint for 

another chemical, which is considered 

to be ‘‘similar’’ in some way (usually on 

the basis of structural similarity and 

similar properties and/or activities). 

A chemical category is a group of 

chemicals whose physical-chemical, 

human health, environmental, 

toxicological, and/or environmental fate 

properties are likely to be similar or 

follow a regular pattern as a result of 

structural similarity, structural 

relationship, or other characteristic(s). A 

chemical category is selected based on 

the hypothesis that the properties of a 

series of chemicals with common 

features will show coherent trends in 

their physical-chemical properties, and 

more importantly, in their toxicological 

effects (OECD, 2007; Ex. #39). 

The use of a category approach means 

that it is possible to identify chemical 

properties which are common to at least 

some members of the category. This 

approach provides a basis for 

establishing trends in properties across 

that category and extends the measured 

data (e.g., toxicological endpoint) to 

similar untested chemicals. 

In the category approach, not every 

chemical in a group needs to have 

exposure-response data in order to be 

evaluated. Rather, the overall data for 

the category as a whole must prove 

adequate to support a risk assessment. 

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The overall data set must allow for an 

assessment of risk for the compounds 

and adverse outcomes that lack 

adequate study. Chemicals may be 

grouped for risk assessment based on 

the following: 

• Common functional group (e.g., 

aldehyde, epoxide, ester, specific metal 

ion); 

• Common constituents or chemical 

classes, similar carbon range numbers; 

• Incremental and constant change 

across the category (e.g., a chain-length 

category); 

• The likelihood of common 

precursors and/or breakdown products, 

via physical or biological processes, 

which result in structurally similar 

chemicals (e.g., the metabolic pathway 

approach of examining related 

chemicals such as acid/ester/salt). 

Within a chemical category, data gaps 

may be filled by read-across, trend 

analysis and Quantitative StructureActivity Relationships (QSARs) and 

threshold of toxicological concern. In 

some cases, an effect can be present for 

some but not all members of the 

category. An example is the glycol 

ethers, where the lower carbon chain 

length members of the category indicate 

reproductive toxicity but the higher 

carbon chain length members of the 

category do not. In other cases, the 

category may show a consistent trend 

where the resulting potencies lead to 

different classifications (OECD, 2007; 

Ex. #39). 

b. Methods of Gap Analysis and Filling 

As a result of grouping chemicals 

based on similarities determined when 

employing the various techniques as 

described above, data gap filling in a 

chemical category can be carried out by 

applying one or more of the following 

procedures: read-across, trend analysis, 

quantitative (Q)SARs and threshold of 

toxicological concern (TTC). 

i. Read-Across Method 

The read-across approach uses 

endpoint information for one chemical 

(the source chemical) to predict the 

same endpoint for another chemical (the 

target chemical), which is considered to 

be ‘‘similar’’ in some way (usually on 

the basis of structural similarity or on 

the basis of the same mode or 

mechanisms of action). Read-across 

methods have been used to assess 

physicochemical properties and toxicity 

in a qualitative or quantitative manner. 

The main application for qualitative 

read-across is in hazard identification. 

ii. Trend Analysis 

Chemical category members are often 

related by a trend (e.g., increasing, 

decreasing or constant) for any specific 

endpoint. The relationship of the 

categorical trend could be molecular 

mass, carbon chain length, or to some 

other physicochemical property. 

The observation of a trend (increasing, 

decreasing or constant) in the 

experimental data for a given endpoint 

across chemicals can be used as the 

basis for interpolation and possibly also 

extrapolation to fill data gaps for 

chemicals with little to no data. 

Interpolation is the estimation of a value 

for a member using measured values 

from other members on ‘‘both sides’’ of 

that member within the defined 

category spectrum, whereas 

extrapolation refers to the estimation of 

a value for a member that is near or at 

the category boundary using measured 

values from internal category members 

(OECD, 2007; Ex. #39). 

iii. QSAR 

A Quantitative Structure-Activity 

Relationship (QSAR) is a quantitative 

relationship between a numerical 

measure of chemical structure, and/or a 

physicochemical property, and an 

effect/activity. QSARs use mathematical 

calculations to make predictions of 

effects/activities that are either on a 

continuous scale or on a categorical 

scale. ‘‘Quantitative’’ refers to the nature 

of the relationship between structurally 

related chemicals, not the endpoint 

being predicted. Most often QSARs have 

been used for determining aquatic 

toxicity or genotoxicity but can be used 

for evaluating other endpoints as well 

(OECD, 2007; Ex. #39). 

Question IV.A.8: Are QSAR, readacross, and trend analysis acceptable 

methods for developing risk 

assessments for a category of chemicals 

with similar structural alerts (chemical 

groupings known to be associated with 

a particular type of toxic effect, e.g., 

mutagenicity) or other toxicologicallyrelevant physiochemical attributes? 

Why or why not? Are there other 

suitable approaches? 

iv. Threshold of Toxicological Concern 

(TTC) 

The Threshold of Toxicological 

Concern (TTC) refers to the 

establishment of an exposure level for a 

group of chemicals below which there 

would be no appreciable risk to human 

health. The original concept proposed 

that a low level of exposure with a 

negligible risk can be identified for 

many chemicals, including those of 

unknown toxicity, based on knowledge 

of their chemical structures. The TTC 

approach is a form of risk 

characterization in which uncertainties 

arising from the use of data on other 

compounds are balanced against the low 

level of exposure. The approach was 

initially developed by the FDA for 

migration of chemicals from consumer 

packaging into food products and used 

a single threshold value of 1.5mg/day 

(referred to as the threshold of 

regulation). 

The TTC principle extends the 

concept used in setting acceptable daily 

allowable intakes (ADIs) by proposing 

that a de minimis value can be 

identified for chemicals with little to no 

toxicity data utilizing information from 

structurally related chemicals with 

known toxicities. 

A decision tree can be developed to 

apply the TTC principle for risk 

assessment decisions: 

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For OSHA purposes the TTC 

approach could be adapted to develop 

an endpoint-specific LETE value for 

chemicals in a specific category where 

little to no toxicity data exist utilizing 

source chemicals within the category 

where toxicity data is available. 

4. Use of Systems Biology and Other 

Emerging Test Data in Risk Assessment 

Toxicity testing is undergoing 

transformation from an approach 

primarily based on pathological 

outcomes in experimental animal 

studies to a more predictive paradigm 

that characterizes critical molecular/

cellular perturbations in toxicity 

pathways using in vitro test systems. 

The paradigm shift is being largely 

driven by the technological advances in 

molecular systems biology such as the 

use of high throughput screening (HTS) 

assays, new computational methods to 

predict chemical properties, and 

computer models able to associate 

molecular events with a biological 

response. The vision, strategies, and 

frameworks for applying the new 

toxicity data to risk-based decision 

making are laid out in landmark reports 

by the National Research Council (NRC, 

2009; Ex. #24, NRC, 2007; Ex. #25). A 

collaborative Federal initiative known 

as ‘‘Tox21’’ has been established 

between the National Toxicology 

Program (NTP), the EPA Office of 

Research and Development, the NIH 

Chemical Genomics Center (NCGC), and 

the Food and Drug Administration 

(FDA) to collaborate on development, 

validation, and translation of innovative 

HTS methods to characterize key steps 

in toxicity pathways (NTP, 2013; Ex. 

#40). Tox21 has already screened over a 

1000 compounds in more than 50 

quantitative HTS assays that have been 

made available to the scientific 

community through publically 

accessible databases (e.g., EPA ACToR, 

NTP CEBS). EPA has launched a 

program, known as ‘‘NexGen’’, to 

implement the NRC vision and advance 

the next generation of risk assessment 

(EPA, 2013b; Ex. #41). NexGen is a 

partnership among EPA, NTP, NCGC, 

AND FDA, along with ATSDR and 

California’s EPA Office of 

Environmental Health Hazard 

Assessment. The objectives of NexGen 

are to pilot the new NRC risk 

assessment framework, refine existing 

bioinformatics systems, and develop 

specific prototype health risk 

assessments. These objectives are 

expected to be achieved through an 

iterative development process that 

includes discussion with scientists, risk 

managers, and stakeholders. 

Question IV.A.9: How should OSHA 

utilize the new molecular-based toxicity 

data, high throughput and computerbased computational approaches being 

generated on many workplace chemicals 

and the updated NRC risk-based 

decision making framework to inform 

future Agency risk assessments? 

B. Considerations for Technological 

Feasibility 

Before adopting a particular 

regulatory alternative, the Agency must 

demonstrate that it is technologically 

feasible. As OSHA currently performs it, 

a technological feasibility analysis is 

often one of the most resource-intensive 


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aspects of the rulemaking process. The 

Agency must identify all of the 

industries that are potentially affected 

and compile the available information 

on current worker exposure and existing 

controls for each industry. On occasion, 

the best information available for 

technological feasibility analyses comes 

from sparse and incomplete data sets. 

Rather than rely exclusively on such 

variable information, OSHA is 

considering the use of exposure 

modeling, such as computational fluid 

dynamics (CFD) modeling, for a more 

complete picture of worker exposures 

and the potential effectiveness of 

different control strategies. 

Additionally, OSHA is looking at other 

sources of information, such as the 

REACH initiative from the European 

Union, that may help the Agency to 

better characterize industries or jobs 

where there is little to no data on 

worker exposures and control 

technologies. 

1. Legal Background of Technological 

Feasibility 

OSHA must demonstrate that a PEL, 

as well as any ancillary provisions, to 

the extend they are being adopted, are 

feasible. In general, OSHA determines 

that a regulatory alternative is 

technologically feasible when it has 

evidence that demonstrates the 

alternative is achievable in most 

operations most of the time. The Agency 

must also show that sampling and 

analytical methods can measure 

exposures at the proposed PEL within 

an acceptable degree of accuracy. OSHA 

makes these determinations in the 

technological feasibility analysis, which 

is made available to the public in the 

OSHA rulemaking docket. 

2. Current Methodology of the 

Technological Feasibility Requirement 

To develop its technological 

feasibility analysis, the Agency must 

first collect the information about the 

industries that are affected by a 

particular hazard, the sources of 

exposure, the frequency of the exposure, 

the number of workers exposed to 

various levels, what control measures or 

other efforts are being made to reduce 

exposure to the hazard, and what 

sampling and analytical methods are 

available. 

This information is typically obtained 

from numerous sources including: 

• Published literature, 

• OSHA Special Emphasis Program 

(SEP) reports, 

• NIOSH reports, such as health 

hazard evaluations (HHE), control 

technology (CT) assessments, surveys, 

recommendations for exposure control, 

and engineering control feasibility 

studies, 

• Site visits, conducted by OSHA, 

NIOSH, or supporting contractors, 

• Information from other 

stakeholders, such as federal and state 

agencies, labor organizations, industry 

associations, and consensus standards, 

• Unpublished information, such as 

personal communications, meetings, 

and presentations, and 

• OSHA Integrated Management 

Information System (IMIS) data. 

With this information, OSHA creates 

profiles that identify the industries 

where exposures occur, what operations 

lead to exposures, and what engineering 

controls and work practices are being 

implemented to mitigate exposures. A 

technological feasibility analysis is 

typically organized by industry sector or 

group of sectors that performs a unique 

activity involving similar activities. 

OSHA identifies the operations that lead 

to exposures in all of these industries, 

and eventually determines the 

feasibility of a PEL by analyzing 

whether the PEL can be achieved in 

most operations most of the time, as an 

aggregate across all industries affected. 

OSHA has also utilized an application 

approach that evaluates the feasibility of 

controls for a specific type of process 

used across a number of industry 

sectors, such as welding, rather than on 

an industry-by-industry basis. 

OSHA develops detailed descriptions 

of how the substance is used in different 

industries, the work activities during 

which workers are exposed, and the 

primary sources of exposure. The 

Agency also constructs exposure 

profiles for each industry, or by job 

category, based on operations 

performed. The Agency classifies 

workers by job categories within those 

industries, based on how similar work 

processes are, and to what extent similar 

engineering controls can be applied to 

control exposures in those processes. 

Each exposure profile contains a list 

of affected job categories, summary 

statistics for each job category and 

subcategories (such as the mean, 

median, and range of exposures), and 

the distribution of worker exposures 

using increments based on the 

regulatory alternatives. 

OSHA’s technological feasibility 

analyses for PEL-setting standards have 

traditionally relied on full-shift, 

personal breathing zone (PBZ) samples 

to create exposure profiles. A PBZ 

sample is the best sample type to 

quantify the inhalation exposure of a 

worker. Area samples are typically not 

used to construct exposure profiles but 

are useful to characterize how much 

airborne contamination is present in a 

work environment and to evaluate the 

effectiveness of engineering and other 

process control measures. 

Exposure profiles are used to establish 

the baseline exposure conditions for 

every job category in affected industries. 

Baseline conditions are developed to 

allow the Agency to estimate the extent 

to which additional controls will be 

required to achieve a level specified by 

a regulatory alternative. 

Next, the technological feasibility 

analysis describes the additional 

controls necessary to achieve the 

regulatory alternatives. OSHA relies on 

its traditional hierarchy of controls 

when demonstrating the feasibility of 

control technology. The traditional 

hierarchy of controls includes, in order 

of preference: Substitution, local 

exhaust ventilation, dust suppression, 

process enclosures, work practices, and 

housekeeping. OSHA considers use of 

personal protective equipment, such as 

respirators, to be is the least effective 

method for controlling employee 

exposure, and therefore, personal 

protective equipment is considered only 

for limited situations in which all 

feasible engineering controls have been 

implemented, but do not effectively 

reduce exposure to below the 

permissible exposure limit. To identify 

what additional controls are feasible, 

the Agency conducts a detailed 

investigation of the controls used in 

different industries based primarily on 

case studies. 

OSHA develops preliminary 

conclusions regarding feasibility of 

regulatory alternatives, by identifying 

the lowest levels of exposure that are 

technologically feasible in workplaces. 

To determine whether an alternative is 

feasible throughout the spectrum of 

affected industries, OSHA studies 

whether the regulatory alternative is 

achievable in most operations most of 

the time by a typical firm. OSHA may 

also determine whether a specific 

process used across a number of 

different industries can be effectively 

controlled. 

3. Role of Exposure Modeling in 

Technological Feasibility 

In many situations, the Agency has 

found it difficult to develop 

comprehensive exposure profiles and 

determine additional controls because 

of limitations associated with the 

available exposure data. These 

information gaps could be filled by 

incorporating exposure modeling into 

the technological feasibility process. 

The limitations associated with the data 

collected include: 

• Limited number of exposure 

samples: On occasions, an exposure 

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profile for a job category may be built 

on a limited number of full-shift 

exposure samples, and the Agency has 

to judge whether the samples available 

are representative of the actual exposure 

distribution for that industry. 

• Limit of Detection (LOD) issues: 

Because only a few exposure samples 

may be available for a job category, the 

analysis may include samples reported 

as ‘‘less than’’ values, high LODs, or 

adjusted LOD values. This causes 

inconsistency in the use of LOD samples 

and may cause the Agency to under- or 

over-estimate the actual exposure 

distribution. 

• Lack of information on controls 

associated with data: Information 

regarding working conditions and 

control strategies associated with 

exposure samples may not be available. 

This makes it difficult for the Agency to 

determine the impact of the control 

strategies for various sources of 

exposure. Additionally, it is common 

that the data does not include 

information about the exact nature of 

the task performed during the sampling 

period. Sometimes, samples may not 

exactly correspond to the job category to 

which OSHA assigns it in the analysis 

because the job activities performed are 

not adequately described. 

• Limitations of traditional industrial 

hygiene sampling: Traditional industrial 

hygiene practices require a ‘‘before and 

after’’ data set to gauge the effectiveness 

of control strategies implemented, and 

changes that occur in the working 

environment during the sampling 

periods. The exact impact of control 

strategies and environmental conditions 

cannot be determined easily with only 

one set of samples obtained at a discrete 

moment in time. It is often the case that 

OSHA does not have the luxury of 

‘‘before and after’’ data sets and must 

determine how the sample set fits into 

the exposure profile. 

• IMIS data limitations: Since the 

Agency may lack exposure data for a 

particular job category or operation, it 

sometimes relies on IMIS data. OSHA 

does not usually rely on IMIS data in its 

exposure profiles unless there are no 

other exposure data available because 

the IMIS data can have some significant 

limitations, which include the 

following: 

Æ Insufficient information to 

determine if a hazard is present in the 

work area in significant amounts as to 

be relevant for an exposure profile. For 

example, an analyst cannot tell from the 

information available in the IMIS 

database if a sample was targeted for the 

hazard in question, or if it was part of 

a larger metal screening process (if the 

hazard is a metal), which typically 

includes up to 16 different metals 

whether they are thought to be present 

in the sampling environment or not. 

Æ Use of SIC codes in historic IMIS 

data, which do not translate directly 

into the NAICS codes currently used in 

the analyses. 

Æ There is no information in the 

database on the end product being 

developed, the action performed to 

produce it, or the materials being used 

when the sample is taken. This limits 

the interpretation of the data, since an 

analyst is not able to attribute the 

exposure to any particular practice or 

process, and cannot recommend 

engineering controls. 

Generally, OSHA has had the most 

success using IMIS data to identify and 

collect enforcement case files for further 

review. Case files from OSHA 

inspections contain more detailed 

information on worker activities and 

exposure controls observed at the time 

an exposure sample is taken. Thus, use 

of case files to a large extent mitigates 

the limitations of using IMIS data. 

For most health standards, OSHA 

does not have the resources to conduct 

site visits to obtain the necessary 

exposure information at firms that are 

representative of all the affected 

industries. In an effort to develop more 

robust exposure profiles, the Agency is 

considering the use of exposure 

modeling, such as computational fluid 

dynamics (CFD) modeling, to 

complement the exposure information 

that is already available from literature, 

site visits, NIOSH and similar field 

investigations, and employer-provided 

data. This technique would potentially 

allow OSHA to better estimate 

workplace exposures in those 

environments were data are limited. 

Question IV.B.1: OSHA described 

how it obtains information necessary to 

conduct its industry profiles. Are there 

additional or better sources of 

information on the industries where 

exposures are likely, the numbers of 

workers and current exposure levels 

that OSHA could use? 

a. Computational Fluid Dynamics 

Modeling To Predict Workplace 

Exposures 

OSHA is considering the use of 

computational fluid dynamics (CFD) to 

model workplace exposure. CFD is a 

discipline of fluid mechanics that uses 

computer modeling to solve complex 

problems involving fluid flows. Fluid 

flow is the physical behavior of fluids, 

either liquids or gases, and it is 

represented by systems of partial 

differential equations that describe 

conservation of energy, mass, and 

momentum. For some physical 

phenomena, such as the laminar flow of 

a fluid through a cylindrical pipe, these 

equations can be solved mathematically. 

Such solutions describe how a fluid will 

move through the specified area, or 

geometry, as a function of time. For 

more complex physical phenomena, 

such as turbulent flow of a fluid through 

a complex geometry, numerical 

approaches are used to solve the 

governing differential equations. As 

such, CFD modeling uses mathematical 

models and numerical methods to 

determine how fluids will behave 

according to a particular set of variables 

and parameters. A mathematical model 

simulates the physical phenomena 

under consideration (i.e. governing 

equations of energy, mass, and 

momentum) and, in turn, a numerical 

method solves that model. Overall, CFD 

modeling enables scientists and 

engineers to perform computer 

simulations in order to make better 

qualitative and quantitative predictions 

of fluid flows. 

Some modeling techniques, such as 

CFD, allow a user to create a virtual 

geometry to simulate actual work 

environments using appropriate 

mathematical models and 

computational methods. The solutions 

predict exposures at any given time and 

in any point in the space of the 

geometry established. A model 

developed with this technique allows 

the user to evaluate exposures in a 

worker’s personal breathing zone and 

identify areas in the work space that 

present high concentrations of the 

contaminant. Because the exposure 

concentration can be solved as a 

function of time, the user can observe 

how concentration increases or 

decreases with time or other changes in 

the model input parameters. This allows 

the user to consider administrative 

controls such as limiting the time of the 

operation, the quantity of material 

emitted by the process, or determining 

how long after an operation a worker 

can safely enter a previously 

contaminated area. In some cases, work 

tasks and processes that are timevarying can be communicated to the 

CFD model through time-varying 

boundary conditions. 

Models require a defined geometry 

(i.e., work space), and this step in the 

model building may be resource 

intensive. To construct geometries of 

complex work environments, OSHA 

would need to gather the necessary 

information to model the work 

environment. This includes taking 

measurements of the work area, 

machinery, engineering control 

specifications (e.g., exhaust face 

velocities, spray systems flow rates), 

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and any other objects or activities that 

may affect the air flow in the area of 

interest. Moreover, gathering sitespecific information for building CFD 

models can be integrated with 

traditional industrial hygiene survey 

activities. OSHA is interested in 

identifying ways to reduce the time and 

money that may be spent recreating 

work environments. One alternative is 

to import facility layouts in an 

electronic format (such as CAD) into the 

modeling software. If an establishment 

has its facility layout in this format, 

then the model designer would not have 

to take physical measurements and 

recreate the work area by 3–D modeling. 

Question IV.B.2: In cases where there 

is no exposure information available, to 

what degree should OSHA rely on 

modeling results to develop exposure 

profiles and feasible control strategies? 

Please explain why or why not. 

Question IV.B.3: What partnerships 

should OSHA seek to obtain 

information required to most efficiently 

construct models of work 

environments? More specifically, how 

should OSHA select facility layouts to 

model that are representative of typical 

work environments in a particular 

industry? Note that the considerations 

should include variables such as work 

area dimensions, production volumes 

and ventilation rates in order to develop 

models for both large and small scale 

operations. 

Models must undergo validation and 

testing to determine if they provide an 

accurate prediction of the physical 

phenomenon under consideration, or in 

this case, the concentrations of air 

contaminants to which workers could 

be potentially exposed. Sensitivity 

analyses can be used to determine if 

model outputs are consistent given 

minor changes to grid cell size and time 

step duration. Grid cell size refers to the 

division of space according to nodes, 

and time step refers to the value 

attributed to the time variable to 

numerically solve the equations with 

reference to the nodes. Another method 

for model evaluation is the comparison 

between the solutions of different 

models to the same problem in that a 

similarity of findings across multiple 

CFD models would provide greater 

confidence in the results. Arguably, the 

best performance evaluation is the 

comparison of model results to those of 

a field experiment that simulates on 

different scales the actual work 

environment. 

This method of predicting workplace 

exposures has some potential 

advantages over traditional industrial 

hygiene sampling methods. Patankar 

(1980; Ex. #42) explains some of the 

advantages of theoretical calculations, 

in a general sense, to predict heat 

transfer and fluid flow processes. Some 

of these are: 

• Low Cost: In many current and 

future applications, the cost of a 

computational method may be lower 

than the corresponding sampling cost. 

As mentioned above, the most resourceconsuming aspect of solid modeling is 

simulating the geometry that resembles 

actual physical space of work 

environments. 

• Speed: A numerical solution to 

predict exposures can be obtained very 

easily in a day. A user could manipulate 

different configurations regarding 

worker positioning and engineering 

controls to find an optimal control 

strategy. 

• Complete information: A computer 

solution provides the values of all 

relevant variables throughout the 

domain of interest. These variables 

cover fluid flow patterns, areas in the 

geometry with highest concentrations of 

contamination, exposure values at any 

point in the geometry, time profile of 

contamination, and exposure results 

based on different control 

configurations. Traditional industrial 

hygiene sampling does not allow for this 

level of analysis as it measures results 

based on a particular work environment, 

and it cannot distinguish how each 

independent variable (e.g., changes in 

the workplace during sampling) affects 

the exposure result. 

• Ability to simulate realistic 

conditions: A computer solution can 

accommodate any environmental 

condition and the values for all 

variables that affect the solution can be 

easily modified to fit a particular 

scenario. 

Patankar (1980; Ex. #42) also 

discusses the disadvantages of 

theoretical predictions to address heat 

transfer and fluid flow processes, and 

they are applicable to exposure 

modeling. The solutions obtained 

depend on the mathematical model 

used to simulate the situation, the value 

of the input parameters, and the 

numerical method used to obtain a 

solution. As Patankar notes, ‘‘a perfectly 

satisfactory numerical technique can 

produce worthless results if an 

inadequate mathematical model is 

employed’’. This is why it is imperative 

that the mathematical model chosen 

actually resembles the physical 

phenomena under consideration. 

The Agency also realizes that even if 

an appropriate mathematical model and 

numerical method are obtained to 

describe contamination in a workplace, 

the exposure modeling approach may 

prove to be more resource-intensive 

than traditional industrial hygiene 

sampling for work environments with 

complex geometries. In these situations, 

OSHA would have to develop a site visit 

protocol for gathering dimensions of the 

work environment of interest. The 

information to be collected includes the 

dimensions of the physical space, the 

ventilation system that affects airflow 

patterns, and other details (such as 

location and size of windows, doors, 

and large obstructions). 

Despite these limitations, modeling 

promises to provide significant 

advantages that could help OSHA 

construct more robust technological 

feasibility analyses while reducing the 

considerable amount of resources the 

Agency already expends on them. In 

addition to CFD modeling, the Agency 

will continue to investigate other 

exposure modeling techniques and their 

applicability in the rulemaking process. 

Question IV.B.4: Should OSHA use 

only models that have been validated? 

If so, what criteria for model validation 

should be employed? 

Question IV.B.5: What exposure 

models are you aware of that can be 

useful for predicting workplace 

exposures and help OSHA create 

exposure profiles and in what 

circumstances? 

At this time, OSHA is primarily 

examining the possibility of 

incorporating CFD models to indoor 

work operations. Most general industry 

and some construction operations are 

performed indoors. As the Agency 

conducts more research on the 

applicability of CFD models to predict 

workplace exposures, outdoor models 

will also be considered. As such, OSHA 

is interested in obtaining input from 

parties experienced in these models. 

Question IV.B.6: Should OSHA 

consider CFD models primarily for 

indoor operations, outdoor operations, 

or both? What limitations exist with 

these two different types of models? 

Various U.S. federal agencies have 

used CFD modeling for projects related 

to indoor air quality and/or 

occupational health and safety. 

Preliminary research indicates that this 

CFD modeling work has been performed 

mostly for academic and research 

purposes. There is little information 

available discussing the use of CFD 

modeling for the purposes of litigation 

and/or regulatory decision-making. 

NIOSH has used CFD on a variety of 

internal research initiatives that involve 

evaluating and controlling airborne 

exposures. Among other projects, 

NIOSH has used CFD modeling to: 

• Evaluate potential exposure 

concentrations to hexavalent chromium 

(CrVI), hexamethylene diisocyanate 

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(HDI), methyl isobutyl ketone (MIBK), 

and others with different ventilation 

control configurations during spray 

painting operations at a Navy aircraft 

paint hangar. In this study, NIOSH also 

tested and validated the predictive 

value of CFD modelling against methods 

of physical sampling by conducting 

workplace air sampling and comparing 

with model results. The project was 

performed with assistance from the 

Naval Facilities Engineering Command 

(NAVFAC) and the Navy Medical Center 

San Diego (NMCSD) (NIOSH, 2011a; Ex. 

#43), 

• Study the effectiveness of 

ventilation systems for controlling 

Tuberculosis (NIOSH, 2010; Ex. #44), 

• Evaluate emission controls for mail 

processing and handling facilities 

(NIOSH, 2010; Ex. #44), 

• Better understand the role airflow 

and ventilation play in disease 

transmission in commercial aircraft 

cabins (NIOSH, 2010; Ex. #44), 

• Simulate different air sampling 

methods to better understand how 

sampling methods can assess exposure 

(NIOSH, 2010; Ex. #44), and 

• Help better understand the 

effectiveness of various forms of 

exposure control technologies in the 

manufacturing and transportation, 

warehousing, and utilities in the 

National Occupational Research Agenda 

(NORA) Sectors (NIOSH, 2011b; Ex. 

#45). 

Additionally, NIOSH has also used 

CFD models in mine safety research: 

• NIOSH conducted a CFD study to 

model the potential for spontaneous 

heating in particular areas of 

underground coal mines (Yuan, L. et al., 

2006; Ex. #46). The purpose of the 

study was to provide insights into the 

optimization of ventilation systems for 

underground coal mines that face both 

methane control and spontaneous 

combustion issues. 

• NIOSH looked at the rate of flame 

spread along combustible materials in a 

ventilated underground mine entry. 

CFD models were used to estimate the 

flame spreading rates of a mine fire 

(Edwards, J. C., and Hwang, C. C., 2006; 

Ex. #47). 

• NIOSH has also used CFD modeling 

to model inert gas injection and oxygen 

depletion in sealed areas of 

underground mines (Trevits, M. A., et 

al., 2010; ; Ex. #48). CFD simulations 

were created to model inert gas 

injections that aim to eliminate 

explosive atmospheres that form in 

sealed mine areas. The CFD model was 

able to quantify oxygen depletion and 

gas leakage rates of the sealed area. 

EPA has conducted a substantial 

amount of work using CFD modeling to 

assess outdoor air quality. However 

there is little information available on 

EPA projects that have used CFD to 

evaluate indoor air quality. 

As part of the Labs21 program, EPA, 

in conjunction with the Department of 

Energy, has published a guidance 

document for optimization of laboratory 

ventilation rates (EPA & DOE, 2008; Ex 

#49). The guidance is geared towards 

architects, engineers, and facilities 

managers, in order to provide 

information about technologies and 

practices to use in designing, 

constructing, and operating safe, 

sustainable, high-performance 

laboratories. EPA advocates the use of 

CFD simulations to determine the 

airflow characteristics of a laboratory 

space in order to improve ventilation 

systems and increase safety and energy 

efficiency. 

The Building and Fire Research 

Laboratory of National Institute of 

Standards and Technology (NIST) 

developed a CFD model to simulate the 

transport of smoke and hot gases during 

a fire in an enclosed space (NIST, 1997; 

Ex. #50). The results of the study and an 

extensive literature review indicated to 

NIST that CFD can have significant 

benefits in the study of indoor air 

quality and ventilation. The report 

resulting from this study provides a 

thorough description of CFD and 

provides recommendations for future 

directions in CFD research. 

The Building and Fire Research 

Laboratory of NIST has also used CFD 

to model the effects of outdoor gas 

generator use on the air concentrations 

of carbon monoxide inside nearby 

buildings (NIST, 2009; Ex. #51). Using 

CONTAM (a mathematical indoor air 

quality model), coupled with CFD 

simulations, the researchers were able to 

determine factors (e.g., generator 

positioning, wind direction) that 

contributed to elevated carbon 

monoxide accumulation in the building. 

As OSHA continues to explore the 

option of incorporating CFD modeling 

into its technological feasibility 

analyses, the Agency will conduct 

further research on existing models. 

b. The Potential Role of REACH in 

Technological Feasibility 

Similar to the evaluation of chemical 

substances by the European Chemicals 

Agency (ECHA) and the European 

Commission before making a decision to 

ban or restrict the use of a substance, 

OSHA must evaluate information on 

health effects, exposure levels, and 

existing controls before setting a new or 

revised PEL. However, ECHA requires 

chemical manufacturers to generate the 

information evaluated by government 

decision-makers, while in the U.S., 

OSHA itself is responsible for 

generating, researching, and evaluating 

the relevant information. 

As explained in more detail above, 

OSHA creates industry profiles to 

evaluate the technological feasibility of 

a standard. The objective of these 

profiles is to estimate the number of 

workers potentially exposed to 

occupational hazards. OSHA relies on 

information from numerous sources 

including the U.S. EPA, U.S. DOL, U.S. 

Census Bureau, NIOSH, scientific 

publications, and site visits to identify 

specific industries where workers are 

potentially exposed to hazards. 

Acquiring data from these sources is 

straightforward and usually achieved 

through standard procedures. However, 

these sources often contain data gaps or 

inconclusive information. Thus, new 

sources of information are needed to fill 

existing data gaps and strengthen 

OSHA’s analyses. 

Since similar types of data are 

currently being developed and 

submitted by manufacturers and 

importers under REACH, this 

information could provide an additional 

reference source for OSHA to utilize. 

The incorporation of REACH data into 

OSHA’s technological feasibility 

analyses could greatly assist the Agency 

in creating a more exhaustive, thorough, 

and complete analysis. The information 

developed during the REACH 

registration process could help OSHA 

better understand the industries, uses, 

processes, and products in which a 

chemical of concern is used, gain 

knowledge about the risk management 

measures and controls currently in 

place, and develop scenarios where 

exposure may be greatest. Exposure 

information generated by manufacturers 

in a chemical safety assessment could 

be valuable for completing exposure 

profiles on chemicals where current 

references for field sampling analytical 

data are limited. In addition, utilizing 

information presented in exposure 

scenarios that describe the conditions 

under which a chemical can be used 

safely (i.e., risk management measures 

and operating conditions) could provide 

insight on currently employed industry 

control methods and their effectiveness. 

While the benefits of incorporating 

REACH data into OSHA’s technological 

feasibility analyses seems promising, 

challenges such as data access and data 

validity have been identified as 

potential drawbacks. Despite provisions 

under REACH that require the public 

availability of data and the sharing of 

data with other government agencies, 

the European Chemicals Agency, which 

maintains the REACH databases, has not 

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yet made some of the information 

available, including information 

generated for and compiled in the 

chemical safety assessment. 

Additionally, some manufacturers and 

importers may be prohibited from 

sharing the data generated for REACH 

directly with other entities for nonREACH purposes due to agreements 

made among the members of groups 

organized under REACH to more 

efficiently share the information needed 

for the registration of a chemical. 

Question IV.B.7: How can exposure 

information in REACH be incorporated 

into OSHA’s technological feasibility 

analysis? 

c. Technological Feasibility Analysis 

With a Focus on Industries With 

Highest Exposures 

OSHA’s technological feasibility 

analysis is one of the most resourceintensive parts of the rulemaking 

process. OSHA typically analyzes 

exposures in all industries and job 

categories within those industries that 

show potential for exposures and 

determine whether a proposed exposure 

limit can be achieved in most operations 

most of the time. These can range from 

industries that are constantly 

experiencing exposures in most job 

categories above an existing PEL or the 

regulatory alternatives, to industries 

where only a few job categories have 

shown elevated exposures. OSHA has 

also utilized an application approach in 

which it analyzed exposure associated 

with a specific process across a number 

of different industries. 

The Agency is investigating whether 

it is appropriate to focus future 

technological feasibility analyses only 

on job categories that have the highest 

exposures. An analysis performed in 

this manner may reduce the amount of 

time and money OSHA has to expend to 

prove feasibility. In many cases the 

control methods applicable for one 

industry may also be effective in 

reducing exposures in other industries. 

By determining the additional 

engineering controls and work practices 

necessary to reduce the most elevated 

exposures to a level specified by a 

regulatory alternative, the Agency could 

propose that similar control strategies 

(wherever applicable) would also be 

effective in reducing lesser exposures to 

that same level. In other words, by 

making feasibility findings in the most 

problematic industries, OSHA would 

argue that all other industries would 

also be able to comply with a regulatory 

alternative. A related possibility is for 

OSHA to make a feasibility 

determination based on enforcement 

activities of the proposed or lower PEL 

in other geographic jurisdictions, e.g., 

other states. 

Question IV.B.8: To what extent and 

in what circumstances should OSHA 

argue that feasibility for a regulatory 

alternative can be established by 

proving the feasibility of reducing the 

highest exposures to the level proposed 

by that regulatory alternative? 

Question IV.B.9: To what extent and 

in what circumstances can OSHA argue 

that feasibility for a regulatory 

alternative can be established by the 

enforcement of a lower PEL [e.g., the 

1989 PEL (See Appendix B)] by an 

individual state or states? 

Question IV.B.10: What are the 

appropriate criteria that OSHA should 

use to assess whether control strategies 

implemented in a process from one 

industry are applicable to a process 

from another industry (e.g., similarity of 

chemicals, type, extent and duration of 

exposures, similar uses)? 

Question IV.B.11: Regardless of the 

industries involved, are there criteria 

that OSHA should use to show that 

control strategies implemented in a 

process from one operation are 

applicable to a process from another 

operation? Please explain. 

The Agency realizes that analyses 

performed in this manner may have 

some implications for smaller firms that 

may find it harder to implement 

resource intensive control strategies 

than larger firms. Additionally, the 

control strategies from the most 

problematic industries may not be 

similar to those that may be needed for 

industries with lower exposures because 

the processes and sources of exposure 

require different control methods. 

Question IV.B.12: How should OSHA 

take into consideration the size of a 

business of facility when determining 

technological feasibility? 

C. Economic Feasibility in Health 

Standards 

The purpose of this section is (1) to 

discuss how and why OSHA currently 

conducts its economic feasibility 

analysis of health standards, and (2) to 

examine approaches to economic 

feasibility that might involve less time 

and fewer resources. 

1. OSHA’s Current Approach to 

Economic Feasibility 

The Agency’s existing approach to 

economic feasibility rests directly on 

relevant language in the OSH Act, as 

interpreted by the courts, requiring 

OSHA to establish that new standards 

are economically feasible. OSHA also 

conducts economic analysis of its 

regulations in compliance with other 

legislation and as a result of executive 

orders that require analysis of the 

benefits and costs of a regulation as a 

whole, and in the case of the Regulatory 

Flexibility Act, some estimate of the 

economic impacts on small entities. 

However, the degree of industry detail 

provided in OSHA’s economic analyses 

is primarily a function of judicial 

interpretation of the economic 

feasibility requirements of the OSH Act. 

The development of the law on 

economic feasibility is discussed in 

detail in Section III. Below we discuss 

potential alternatives to current 

methods of economic feasibility 

analysis, and then follow with a brief 

discussion on how the other analytical 

requirements OSHA is required to meet 

might be satisfied. 

As guided by the courts, OSHA 

develops economic feasibility analyses 

that cover every affected industry and 

process. OSHA has not always taken 

this position. For example, in its 

economic and technological feasibility 

analysis of benzene, OSHA examined 

only industries believed to be the worst 

in terms of significant exposure to 

benzene. Since then, however, OSHA 

has attempted to cover all affected 

industries in its feasibility analysis. 

The courts have suggested that the 

economic feasibility analysis must be 

reasonably detailed. In the Air 

Contaminants case, the court said: 

Indeed, it would seem particularly 

important not to aggregate disparate 

industries when making a showing of 

economic feasibility . . . [R]eliance on such 

tools as average estimates of cost can be 

extremely misleading in assessing the impact 

of particular standards on individual 

industries. AFL–CIO v. OSHA, 965 F.2d 962, 

982 (11th Cir. 1992) (‘‘Air Contaminants’’). 

(Ex. #8) 

However, the court added: 

We are not foreclosing the possibility that 

OSHA could properly find and explain that 

certain impacts and standards do apply to 

entire sectors of an industry. Two-digit SICs 

could be appropriate, but only if coupled 

with a showing that there are no 

disproportionately affected industries within 

the group. Air Contaminants, 965 F.2d at 982 

n.28 

In the hexavalent chromium case, 

Public Citizen Health Research Group v. 

United States Dep’t of Labor, 557 F.3d 

165, 178 (3d Cir. 2009; Ex. #14), the 

court recognized that OSHA had the 

flexibility to demonstrate technological 

feasibility on a process or activity rather 

than industry-by-industry basis, if the 

processes or activities are sufficiently 

similar from industry to industry. The 

court, however, did not address the 

question of whether the same flexibility 

applies to economic feasibility. OSHA, 

especially in health standards, has tried 

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to provide the most detailed analysis of 

industries and processes that resources 

permit. For most recent health 

standards, this has meant the use of the 

lowest level industry codes for which 

industry data are available, and where 

more than one process is used in an 

industry, consideration of each process 

separately. Further, in order to assure 

that a regulation does not alter the 

competitive structure of an industry, 

OSHA normally analyses three size 

classes of employer within each 

industry: All establishments, small 

firms as defined by SBA, and small 

firms with fewer than twenty employees 

(always smaller than the SBA 

definitions). For the typical OSHA 

substance-specific health standard, 

OSHA analyses each of the controls for 

each of the many processes in which the 

substance might appear, and then of 

each industry in which any process 

might appear, and then of three sizes of 

establishment within the industry. 

Finally, OSHA examines the varying 

levels of exposure and controls within 

an industry and develops analyses that 

reflect these differences within an 

industry. In terms of the form of the 

analysis, OSHA has followed the advice 

of the D.C. Circuit to ‘‘construct a 

reasonable estimate of compliance costs 

and demonstrate a reasonable likelihood 

that these costs will not threaten the 

existence or competitive structure of an 

industry.’’ United Steelworkers v. 

Marshall, 647 F.2d 1189, 1272 (D.C. Cir. 

1980; Ex. #12) (‘‘Lead I’’). 

In response to this guidance, OSHA 

develops detailed estimates of the costs 

of a health standard for each affected 

industry, and by the three size 

categories of establishment. The result is 

that the economic analyses of health 

standards routinely contain a series of 

tables showing costs for each industry 

by multiple size classes of firms within 

the industry, and sometimes for more 

than one process per industry. Each 

entry in these tables is documented by 

detailed explanations of how the costs 

were estimated for each industry and 

size class and level of exposure. 

OSHA then makes a determination for 

each industry whether or not these costs 

are likely to threaten the existence or 

competitive structure of that industry. 

In order to do this, OSHA first 

constructs a ‘‘screening analysis’’ for 

each industry. For the purposes of this 

screening analysis, OSHA combines its 

estimates on the costs per establishment 

of various sizes with statistical data on 

the profits and revenues of the affected 

establishment sizes, and then calculates 

costs as a percentage of profits and 

revenues. For most industries, the costs 

in comparison to revenues and profits 

are so small that, in OSHA’s view, no 

reasonable person could think that the 

costs could possibly be expected to 

threaten the existence or competitive 

structure of an industry. Where the costs 

are not this small, OSHA conducts a 

variety of further economic analysis, 

depending on the economic situation, 

nature of the costs, the affected 

industry, and the economic data 

available. 

This basic approach to economic 

feasibility analysis has been used for 

many health standards, and the 

approach has generally been successful 

in assuring that OSHA standards are 

economically feasible. In the PELs 

rulemaking, where OSHA tried a more 

general approach, the court found the 

level of detail inadequate. Similarly, 

OSHA has encountered problems when 

the Agency did not have an adequate 

level of detail with respect to the 

exposure profile and the technological 

feasibility analysis, such as for dry-color 

formulators of cadmium pigments. 

OSHA’s eight lookback studies, 

conducted under both Sections 610 of 

the Regulatory Flexibility Act and 

Section 5 of Executive Order 12866, 

have not found any instance in which 

subsequent study showed that a 

standard had threatened the existence of 

or brought about massive dislocation 

within an industry. 

OSHA can reasonably say that it has 

found a methodology such that the 

Agency’s determinations of economic 

feasibility have both been considered 

adequate by the courts and proven to be 

accurate in determining regulations to 

be feasible when re-evaluated by 

retrospective analysis. However, the 

resulting methodology is extremely 

resource intensive and time-consuming 

because OSHA always has to make 

detailed cost estimates and provide 

detailed statistical data for every single 

process and industry affected. For this 

reason, OSHA wants to consider 

whether there may be methods that can 

short-cut this process and still meet all 

of OSHA’s legal requirements. 

The remainder of this section 

examines two kinds of alternative 

approaches to accelerating the process 

and reducing the resources needed to 

produce health standards. One kind of 

alternative involves formulating health 

standards differently. The second kind 

involves different kinds of analysis 

OSHA might perform. 

2. Alternative Approaches to 

Formulating Health Standards That 

Might Accelerate the Economic 

Feasibility Analysis 

One approach to simplifying, 

speeding up, and making the 

development of standards less resource 

intensive would be to have the 

standards themselves address health 

issues in a way that involves less 

analysis for any given standard. Health 

standards can be analyzed faster to the 

extent that there are fewer processes 

and/or fewer industries to analyze. It 

would be less time consuming for 

OSHA to analyze a health standard for 

a single process rather than a single 

substance that is found in dozens of 

processes. OSHA already has a variety 

of process-oriented standards that 

partially address health hazards in such 

areas as abrasive blasting, welding, and 

electroplating. Control banding also 

represents an approach that, following 

the hazard assessment, examines 

controls for specific processes. In 

control banding, the hazards are generic, 

but the controls are process specific. 

Process-oriented approaches would be 

most useful for processes widely used in 

a variety of settings—abrasive blasting, 

degreasing, welding, etc. Industry-byindustry economic feasibility analysis 

for a process-oriented approach would 

be enormously simplified by the fact the 

controls and their costs would be very 

similar across industries. As a result, 

OSHA could develop more detailed and 

more secure cost estimates, with full 

opportunities for a variety of affected 

parties to comment on those estimates. 

This approach might also serve to 

greatly simplify the technological 

feasibility analysis. On the other hand, 

since process-oriented standards 

commonly involve multiple substances, 

risk assessment issues might be more 

complex. 

A related approach to speeding up at 

least portions of substance specific 

health standards might be to regulate a 

single substance process by process in 

multiple rulemakings—for example, 

regulate exposures to hexavalent 

chromium in electroplating, then in 

welding, and then painting. By 

producing process standards in this 

manner, rather than waiting until 

analyses of all processes and industries 

is completed, OSHA could potentially 

address the most severe exposures much 

more rapidly. This approach could also 

allow OSHA to ignore processes where 

the exposures are likely to be small and 

the chance of exceeding a PEL minimal. 

Though this approach might result in 

portions of a substance-specific 

standard being produced more quickly, 

the approach would probably require 

more resources for multiple hearings 

and docket analyses. A major 

disadvantage of this approach is that it 

would result in the possibility that 

workers in industries not yet regulated 

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would have to endure exposures higher 

than those in regulated industries. 

Another disadvantage might be that the 

risk assessment would be subject to 

multiple public hearings as each 

industry or process was regulated. 

3. Alternative Analytic Approaches to 

Economic Feasibility of Health 

Standards 

A different approach to producing 

less resource-intensive and timeconsuming economic feasibility 

analyses would be to re-examine 

whether OSHA’s basic approach of 

estimating the costs of each process, 

industry, size class, and possible level 

of control is really necessary in all cases 

given how the courts have defined 

economic feasibility. The key to meeting 

the legal requirements is to return to the 

concept of economic feasibility. In the 

Lead I decision, the court stated: 

A standard is feasible if it does not threaten 

‘‘massive dislocation’’ to . . . or imperil the 

existence of the industry. No matter how 

initially frightening the projected . . . costs 

of compliance appear, a court must examine 

those costs in relation to the financial health 

and profitability of the industry and the 

likely effect of such costs on unit consumer 

prices. More specifically . . . the practical 

question is whether the standard threatens 

the competitive stability of an industry. Lead 

I, 647 F.2d at 1265 (citations omitted). (Ex. 

#12) 

As the court recognized, this is a 

strong criterion. In the real world, 

industries are rarely eliminated or have 

their competitive structure radically 

altered for reasons related to changes in 

their costs, and it is changes in costs 

that courts recognized as the principle 

reason a regulation might not be 

economically feasible. Radical changes 

in industries tend to come from two 

major causes. Most are the result of 

changes in demand such that the public 

is no longer interested in the product or 

service an industry provides, for such 

reasons as technological obsolescence or 

the existence of better substitutes. Some 

radical changes in industries are the 

result of foreign competition. However, 

foreign competition applies largely, in 

an OSHA context, to manufacturing, but 

not to construction, utilities, domestic 

transportation, or most services that 

OSHA regulates. 

OSHA is not aware of any instance in 

which an OSHA regulation eliminated 

or altered the competitive structure of 

an industry—though in some cases, a 

combination of liability-based concerns, 

environmental regulations, and OSHA 

regulation may have radically altered 

the use of a product. For example, 

asbestos is not used in many 

applications where it was once 

commonplace. Benzidine-based dyes 

have disappeared from the U.S. 

marketplace. However, these cases had 

no effect on the viability of user 

industries or their employment. 

Insulation contractors still install 

insulation—it just no longer contains 

asbestos. Dyers continue to dye textiles 

and leather all the colors benzidenebased dyes imparted, but without using 

benzidene-based dyes. The chief effect 

has been substitution away from a 

substance. This has resulted in serious 

economic impacts on a limited number 

of producers of the substance but little 

economic impact on the thousands of 

users of the substance who simply 

found a substitute. It would seem that 

such substitution away from a substance 

is not the kind of economic change that 

would make a regulation economically 

infeasible. 

OSHA might be able to place major 

emphasis on evidence that a significant 

portion of an industry is already 

meeting a standard. Such evidence is an 

obvious indication that a standard is 

both technologically and economically 

feasible for that industry. After all, the 

actual fact that a majority of employers 

of all sizes in an industry is meeting a 

standard, while remaining viable, 

should be more convincing than a set of 

cost estimates in an economic analysis 

predicting that employers in a given 

industry could meet the standard. 

Actual empirical evidence of a 

proposition is normally considered 

superior to theoretical evidence for a 

proposition. There are several reasons 

why many or most employers in an 

industry may already meet a standard— 

these include ease of meeting the 

standard, industry consensus standards, 

and concern about liability. 

Similarly, the fact that a state or other 

jurisdiction has already implemented a 

requirement and that firms within the 

state are generally following the 

requirement would represent very 

strong evidence that a requirement is 

economically and technologically 

feasible. For example, twenty-two states 

currently operate their own OSHA 

programs that cover both private sector 

and State and local government 

employees, and five states cover public 

employees only. Of the twenty-two 

states that cover both private and public 

sector employees, five states (South 

Carolina, Minnesota, Tennessee, 

Vermont and Washington) are still 

enforcing the 1989 PELs, and did not 

revert to the less protective PELs when 

the Court remanded the Air 

Contaminants rule. (Ex. #8) Michigan is 

also enforcing the 1989 PELs in general 

industry, but not in construction. Three 

states (Connecticut, Illinois, and New 

York) are enforcing the 1989 PELs in the 

public sector only. California enforces 

its own PELs which in many cases are 

substantially lower than OSHA’s. 

Situations in which most firms in a state 

meet a potential requirement of a 

standard are particularly convincing 

because they show that employers are 

not only able to carry out the 

requirement, but can do so even in 

competition with employers who are 

not required to meet such a 

requirement. 

Nevertheless, OSHA is aware that 

some care must be taken with evidence 

that all or most firms in an industry or 

in an industry within a state meet a 

requirement. It is particularly important 

to determine whether those who do not 

meet the requirement might require 

fundamentally different controls, have 

different costs, or operate in a different 

market in spite of being in the same 

statistical industry. Consider a standard 

addressing a specific metal. Most firms 

in an industry may find the standard 

easy to meet because they only use the 

metal in alloys that call for a very small 

percentage of the metal. However, those 

firms that use alloys with high 

percentages of the metal might be 

unable to meet the standard. This would 

not be apparent looking solely at 

aggregate industry data. OSHA should 

take reasonable steps to determine that 

those that did not meet the standard do 

not have important technological or 

economic characteristics that are 

different from those that did. 

Under this approach, OSHA could 

conclude that a standard is feasible 

where a state already had such a 

standard if it first determines that (1) the 

standard is enforced; (2) employers in 

the state in fact meet the standard; and 

(3) which of the relevant industries and 

technologies are represented within that 

state. 

However, in spite of these caveats, it 

would frequently take OSHA less time 

and fewer resources to demonstrate that 

a standard is technologically and 

economically feasible by showing that 

employers in the industry already meet 

the standard than by the full 

identification of control technologies, 

exposure levels achieved by those 

technologies, the costs of the 

technologies, and the economic impacts 

of these technologies that OSHA now 

undertakes. 

As noted above, at one point in the 

Lead I decision, the court suggested 

OSHA develop a ‘‘reasonable estimate of 

costs.’’ However at another point in this 

decision the same court clarified: 

[T]he court probably cannot expect hard 

and precise estimates of costs. Nevertheless, 

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the agency must of course provide a 

reasonable assessment of the likely range of 

costs of its standard, and the likely effects of 

those costs on the industry . . . And OSHA 

can revise any gloomy forecast that estimated 

costs will imperil an industry by allowing for 

the industry’s demonstrated ability to pass 

through costs to consumers. Lead I, 647 F.2d 

at 1266. (Ex. #12) 

OSHA has made little use of the 

concept of a likely range of costs or of 

developing generic approaches to 

determining a reasonable likelihood that 

these costs will not threaten the 

existence or competitive structure of an 

industry. 

OSHA could significantly reduce its 

resource and time expenditures by 

providing ranges of costs, given that the 

upper end of the range provides ‘‘a 

reasonable likelihood that these costs 

will not threaten the existence or 

competitive structure of an industry.’’ 

Such an approach would not only 

reduce OSHA’s time and effort but also 

that of the interested public. Too often 

stakeholders devote significant time and 

effort questioning cost estimates when 

even the stakeholders’ alternative cost 

estimate would have no effect on 

whether the costs would threaten the 

existence or competitive structure of an 

industry. The simple fact is that both 

OSHA and its stakeholders spend far too 

much time examining the accuracy of 

cost estimates even when the highest 

cost estimates considered would have 

little effect on the determination of 

economic feasibility. 

OSHA could also make more effort to 

clarify historically the circumstances 

under which regulations of any kind 

have eliminated or altered the 

competitive structure of an industry. As 

noted above, OSHA has yet to find an 

instance in which OSHA regulations 

eliminated or altered the competitive 

structure of an industry. A more 

thorough exploration of past 

experiences with OSHA regulations 

might simplify OSHA analyses and 

make it more empirically based in a 

variety of situations. 

OSHA believes that it may be able to 

meet the requirements of Executive 

Orders 12866 and 13563 and the 

Regulatory Flexibility Act without the 

kind of industry-by-industry detail that 

OSHA now provides in its economic 

analyses. The requirements of executive 

orders for analysis of costs and benefits 

do not include requirements that they 

be made available on an industry-byindustry basis, and OIRA encourages the 

reporting of ranges as opposed to 

precise but possibly inaccurate point 

estimates. OSHA believes that the 

requirements of the executive orders 

and for determining if a regulatory 

flexibility analysis or Small Business 

Regulatory Enforcement Fairness Act 

(SBREFA) Panel is needed can, in most 

cases, be met by focusing on those 

sectors and size classes where the most 

severe impacts are expected. 

Question IV.C.1: Should OSHA 

consider greater use of process oriented 

regulations, such as regulations on 

abrasive blasting, welding, or 

degreasing, as an approach to health 

standards? Should such an approach be 

combined with a control banding 

approach? 

Question IV.C.2: Should OSHA 

consider issuing substance-specific 

standards in segments as the analysis of 

a particular process or industry is 

completed rather than waiting until 

every process and industry using a 

substance has been thoroughly 

analyzed? 

Question IV.C.3: To what extend and 

in what circumstances can OSHA argue 

that feasibility for a regulatory 

alternative can be established by the 

enforcement of a lower PEL (e. g., the 

1989 PEL) by an individual state or 

states? 

4. Approaches to Economic Feasibility 

Analysis for a Comprehensive PELs 

Update 

Following the Eleventh Circuit’s 

direction in the Air Contaminants case 

(956 F.2d at 980–82; Ex. #8) and in 

Color Pigments Mfrs. Ass’n v. OSHA, 16 

F.3d 1157, 1161–64 (11th Cir. 1994; Ex. 

#13), OSHA has typically performed its 

economic feasibility analyses on an 

industry-by-industry basis using the 

lowest level industry codes for which 

industry data are available. While such 

an approach best insures that the effect 

of the standard on small industry 

segments will be considered, it is very 

resource intensive. If OSHA were 

required to use of this approach to 

address feasibility for a comprehensive 

PELs update, which would require 

addressing the feasibility of new PELs 

for hundreds of chemicals in hundreds 

of industry segments, it might require 

more resources than the agency would 

have available. 

There are good reasons to think that 

the OSH Act does not require such a 

detailed level of economic analysis to 

support a feasibility finding. The 

purpose of the OSH Act is to assure all 

workers ‘‘safe and healthful working 

conditions,’’ and therefore it is unlikely 

that Congress intended for OSHA to 

meet such demanding analytical 

requirements if it meant that the agency 

could not issue a standard addressing 

well-recognized hazards. See, e.g., 

Public Citizen Health Research Group v. 

Dep’t of Labor, 557 F.3d 165, 178–79 (3d 

Cir. 2009; Ex. #14) (‘‘Hexchrome’’) 

(rejecting interpretation that OSH Act 

required OSHA to research all 

workplace operations involving 

hexavalent chromium exposure to prove 

feasibility, which would ‘‘severely 

hinder OSHA’s ability to regulate 

exposure to common toxins’’); American 

Dental Ass’n v. Martin, 984 F.2d 823, 

827 (7th Cir. 1993; Ex. #53) (OSHA not 

required to regulate ‘‘workplace by 

workplace’’); Assoc. Bldrs & Contrs. Inc. 

v. Brock, 862 F.2d 63, 68 (3d Cir. 1988; 

Ex. #54) (‘‘A requirement that the 

Secretary assess risk to workers and 

need for disclosure with respect to each 

substance in each industry would 

effectively cripple OSHA’s performance 

of the duty imposed on it by 29 U.S.C. 

655(b)(5); a duty to protect all 

employees, to the maximum extent 

feasible.’’). 

Indeed, the requirement that an 

OSHA standard not threaten ‘‘massive 

dislocation’’ or ‘‘imperil the existence’’ 

of an industry is an outgrowth of the 

idea that OSHA may adopt standards 

that may cause marginal firms to go out 

of business if they are only able to make 

a profit by endangering their employees. 

See Industrial Union Dep’t, AFL–CIO v. 

Hodgson, 499 F.2d 467, 478 (XX Cir. 

1974; Ex. #55). And the notion that the 

determination must be made on an 

industry basis arises from cases in 

which OSHA attempted to do just that; 

the statute does not require feasibility to 

be evaluated in this way. See Lead I, 647 

F.2d at 1301 (where OSHA attempted to 

determine the feasibility of the lead 

standard on an industry-by-industry 

basis, noting that the parties did not 

dispute that feasibility was to be 

determined in that manner); 

Hexchrome, 557 F.3d at 178 (‘‘nothing 

in 29 U.S.C. 655(b)(5) requires OSHA to 

analyze employee groups by industry, 

nor does the term ‘industry’ even 

appear’’). The approach articulated by 

the Air Contaminants court, which 

places an affirmative duty on OSHA to 

establish that proposed standards would 

not threaten even the smallest industry 

segments before adopting a standard, 

creates a heavy analytical burden that is 

not necessarily required by the statute. 

As the Lead I court notes, in the case 

of a standard requiring an employer to 

adopt only those engineering and 

administrative controls that are feasible, 

what really is at stake in OSHA’s 

feasibility determinations is whether 

OSHA has justified creating a 

presumption that the implementation of 

such controls are feasible. 647 F.2d at 

1269–70. Thus, OSHA need not ‘‘prove 

the standard certainly feasible for all 

firms at all times in all jobs.’’ 647 F.2d 

at 1270. The court recognized that under 

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this approach, some employers might 

not be able to comply with a standard, 

but noted that the statute offers those 

employers several alternatives: 

requesting a variance, asserting a 

feasibility defense in an enforcement 

proceeding, or petitioning the agency to 

revise the standard. 647 F.2d at 1270. 

As noted above, most of OSHA’s 

current PELs are over 40 years old, and 

are based on science that is even older. 

It seems unlikely that a statute enacted 

to protect workers against chemical 

health hazards would preclude OSHA 

from updating hundreds of those PELs 

unless it can show that each is feasible 

in each of the smallest industry 

segments in which the chemical is used. 

The question, then, is what level of 

analysis would be sufficient to justify a 

presumption that the standard is 

feasible, shifting the burden to the 

employer as allowed by Lead I. 

If OSHA moved forward with a global 

PELs update, the Agency might consider 

analyzing economic feasibility at a 

higher level than it has typically 

employed in substance specific health 

standards. In order to do so, OSHA 

would need to develop criteria as to 

what chemicals are suited to be part of 

a PELs rulemaking rather than subject to 

a substance-specific rulemaking. For 

example, if the rulemaking record 

showed that, for a specific chemical 

application group, generally available 

exposure controls had not been 

successful in achieving the proposed 

PEL, then this chemical or at least the 

application group would be transferred 

from updated PELs rulemaking to being 

a candidate for further study and 

possible inclusion in a substancespecific rulemaking. The goal under this 

approach would be to develop a 

reasonable basis for believing that the 

chemicals and application groups 

remaining in a PELs-update rulemaking 

are (1) likely to be economically 

feasible; and (2) subject to relatively 

simple and easily-costed controls that 

are likely to be relatively homogenous 

across industries. 

As a result, rather than accumulating 

data at the lowest industry level 

available regarding exposures and 

controls needed for each chemical for 

which a new PEL would be adopted, 

OSHA could consider a more general 

approach. For example, OSHA might 

conduct an economic feasibility analysis 

at the industry level for which sufficient 

exposure data are currently available. It 

might use a control banding approach in 

order to determine the types of controls 

necessary to comply with a new PEL, 

and validate models to implement each 

type of control based on variables such 

as establishment size and process type. 

The results of this analysis would be 

used to build up costs at the industry 

level. It is possible that the results of 

such an analysis might be better 

characterized in ranges, and of sufficient 

precision to establish feasibility at a 

level as low as the method that OSHA 

typically uses. Under this approach, a 

determination made in this way would 

be presumptively sufficient to establish 

feasibility in the absence of contrary 

evidence provided by commenters. If 

such evidence were presented, OSHA 

would address it and incorporate it into 

its feasibility analysis supporting the 

final rule. 

Question IV.C.4: Should OSHA 

consider providing ranges of costs for 

industries in situations where even the 

upper range of the costs would 

obviously not provide a threat to the 

existence of competitive structure of an 

industry? 

Question IV.C.5: What peer-reviewed 

economics literature should OSHA 

consult when determining whether the 

competitive structure of an industry 

would be altered? Are there any 

instances where an OSHA standard did 

threaten the existence or competitive 

structure of an industry? What were 

they and what is the evidence that an 

OSHA standard was the origin of the 

difficulties? 

Question IV.C.6: Should OSHA 

consider and encourage substitution and 

elimination of substances that cause 

significant risk in workplaces even if 

such substitution or elimination will 

eliminate or alter the competitive 

structure of the industry or industries 

that produce the hazardous substance? 

Question IV.C.7: Are there other 

approaches OSHA could use that would 

provide for more timely and less 

resource-intensive economic feasibility 

analyses? 

Question IV.C.8: In determining the 

level of industry detail at which OSHA 

should conduct an economic feasibility 

analysis for a comprehensive PELs 

update, what considerations should 

OSHA take into account? What level of 

detail do you think is sufficient to 

justify the presumption of feasibility for 

such a standard? Please explain. 

Question IV.C.9: Are the 

methodologies suggested above 

appropriate to establish economic 

feasibility for a comprehensive PELs 

update? Why or why not? What other 

cost effective methods are available for 

OSHA to establish economic feasibility 

for such a rulemaking? 

Question IV.C.10: What factors should 

OSHA consider in determining whether 

a chemical should be part of an overall 

PELs update or subject to substancespecific rulemaking? Should OSHA 

consider some application groups for a 

given chemical as subject to a PELs 

update rulemaking if some other 

application groups present feasibility 

issues that make them inadvisable 

candidates for a PELs rulemaking? 

V. Recent Developments and Potential 

Alternative Approaches 

Wide access to information on the 

Internet and the development of a global 

economy has shifted occupational safety 

and health from a domestic to a global 

concern. Countries often struggle with 

similar experiences and challenges 

related to exposure to hazardous 

chemicals, and sharing information and 

experiences across borders is a common 

practice. Global data sharing allows for 

the widespread and rapid dissemination 

of available chemical information to 

employers, employees, managers, 

chemical suppliers and importers, risk 

managers, or anyone with access to the 

Internet. The development of hazard 

assessment tools that take advantage of 

readily available hazard information 

make it possible for employers to 

implement effective exposure control 

strategies without the need to rely solely 

on OELs. 

Some of these resources for data and 

tools that OSHA may use more 

systematically in the future for 

hazardous chemical identification 

and/or assessment are addressed in 

Section V. 

A. Sources of Information About 

Hazardous Chemicals 

In order to design and implement 

appropriate protective measures to 

control chemical exposures in the 

workplace, employers need reliable 

information about the identities and 

hazards associated with those 

chemicals. OSHA is considering ways in 

which recently developed data sources 

could be used by the Agency and 

employers to more effectively manage 

chemical hazards in the workplace. 

Developments in the use of structure— 

activity data for grouping chemicals 

having similar properties, the 

Environmental Protection Agency’s 

High Production Volume (HPV) 

Chemicals, OSHA’s Hazard 

Communication standard and the 

Globally Harmonized Hazard 

Communication Standard, health hazard 

banding, the European Union’s 

Registration, Evaluation, Authorization, 

and Restriction of Chemicals (REACH), 

are discussed here. OSHA is interested 

in stakeholders’ comments on how the 

Agency may make use of any of these 

data sources or other alternative data or 

information sources not discussed here 

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to better manage workplace chemical 

exposures. 

1. EPA’s High Production Volume 

Chemicals 

One potential source of relevant and 

timely information on chemicals that 

OSHA may make better use of in the 

future is the data on High Production 

Volume chemicals that are being 

collected by the EPA and the 

Organization for Economic Cooperation 

and Development (OECD). The OECD 

program lists approximately 5,000 

chemicals on its list, and OSHA has 

determined that 290, or 62 percent of 

the 470 substances with PELs are 

included on the OECD list. 

Under the HPV program, EPA has 

identified over 2,000 chemicals that are 

produced in quantities of one million 

pounds a year or more in the United 

States. It would appear that these 

chemicals are thus economically 

significant in the US, and there are 

likely to be a large number of workers 

exposed to them. Through the HPV 

Challenge program, EPA encouraged 

industry to make health and 

environmental effects data on these HPV 

chemicals publicly available. To date, 

data on the properties of approximately 

900 HPV chemicals has been made 

available through the Agency’s High 

Production Volume Information System 

(HPVIS) (U.S. EPA, 2012a; Ex. #56). For 

each HPV chemical, the database 

includes information on up to 50 

endpoints on physical/chemical 

properties, environmental fate and 

pathways, ecotoxicity, and mammalian 

health effects. EPA has also used this 

information to generate publicly 

available chemical hazard 

characterizations, which provide a 

concise assessment of the raw technical 

data on HPV chemicals and evaluate the 

quality and completeness of the data 

received from industry (U.S. EPA, 

2013d; Ex. #63). 

Data on HPV chemicals submitted 

through the OECD’s program are 

available through its Global Portal to 

Information on Chemical Substances, 

eChemPortal (OECD, 2013; Ex. #58). In 

addition to searching data collected 

through the EPA HPV and OECD HPV 

programs, eChemPortal allows for 

simultaneous searching of 26 databases 

for existing publicly available data on 

the properties of chemicals, including: 

physical/chemical properties, 

environmental fate and behavior, 

ecotoxicity, and toxicity. 

Question V.A.1. How might publicly 

available information on the properties 

and toxicity of HPV chemicals be 

utilized by employers to identify 

chemical hazards and protect workers 

from these hazards? OSHA is also 

interested to hear from commenters who 

may currently make use of these data in 

their worker protection programs. 

2. EPA’s CompTox and ToxCast 

EPA has also launched an effort to 

prioritize the tens of thousands 

chemicals that are currently in use for 

testing and exposure control. Through 

its computational toxicology (CompTox) 

research, the U.S. Environmental 

Protection Agency (EPA) is working to 

figure out how to change the current 

approach used to evaluate the safety of 

chemicals. CompTox research integrates 

advances in biology, biotechnology, 

chemistry, and computer science to 

identify important biological processes 

that may be disrupted by the chemicals 

and trace those biological disruptions to 

a related dose and human exposure. The 

combined information helps prioritize 

chemicals based on potential human 

health risks. Using CompTox, thousands 

of chemicals can be evaluated for 

potential risk at a small cost in a very 

short amount of time. A major part of 

EPA’s CompTox research is the Toxicity 

Forecaster (ToxCastTM). ToxCast is a 

multiyear effort launched in 2007 that 

uses automated chemical screening 

technologies, called ‘‘highthroughput 

screening assays,’’ to expose living cells 

or isolated proteins to chemicals. The 

cells or proteins then are screened for 

changes in biological activity that may 

suggest potential toxic effects. 

These innovative methods have the 

potential to limit the number of required 

animal-based laboratory toxicity tests 

while, quickly and efficiently screening 

large numbers of chemicals. The first 

phase of ToxCast, called ‘‘proof of 

concept’’, was completed in 2009, and 

it evaluated more than 300 well studied 

chemicals (primarily pesticides) in more 

than 500 high-throughput screening 

assays. Because most of these chemicals 

already have undergone extensive 

animal-based toxicity testing, this 

enables EPA researchers to compare the 

results of the high-throughput assays 

with those of the traditional animal 

tests. (EPA, 2014a; Ex. #59) 

Completed in 2013, the second phase 

of ToxCast evaluated over 2,000 

chemicals from a broad range of sources, 

including industrial and consumer 

products, food additives, and 

potentially ‘‘green’’ chemicals that 

could be safer alternatives to existing 

chemicals. These chemicals were 

evaluated in more than 700 highthroughput assays covering a range of 

high-level cell responses and 

approximately 300 signaling pathways. 

ToxCast research is ongoing to 

determine which assays, under what 

conditions, may lead to toxicological 

responses. The results of this research 

then can be used to suggest the context 

in which decision makers can use the 

data. The EPA’s Endocrine Disruptor 

Screening Program already has begun 

the scientific review process necessary 

to begin using ToxCast data to prioritize 

the thousands of chemicals that need to 

be tested for potential endocrine-related 

activity. Other potential uses include 

prioritizing chemicals that need testing 

under the Toxic Substances Control Act 

and informing the Safe Drinking Water 

Act’s contaminant candidate lists. (EPA, 

2014b; Ex. #60) EPA contributes the 

results of ToxCast to a Federal agency 

collaboration called Toxicity Testing in 

the 21st Century (Tox21). Tox21 pools 

those results with chemical research, 

data and screening tools from the 

National Toxicology Program at the 

National Institute of Environmental 

Health Science, the National Institutes 

of Health’s National Center for 

Advancing Translational Sciences and 

the Food and Drug Administration. 

(EPA, 2014b; Ex. #60) 

Thus far, Tox21 has compiled 

highthroughput screening data on 

nearly 10,000 chemicals. All ToxCast 

chemical data are publicly available for 

anyone to access and use through userfriendly Web applications called 

interactive Chemical Safety for 

Sustainability (iCSS) Dashboards at 

http://actor.epa.gov/actor/faces/. 

OSHA could use this publicly 

available information on chemical 

properties and toxicity as a part of the 

Agency’s risk assessments that support 

the revision and development of 

permissible exposure limits. Tox21 

could also be used by the Agency for 

screening chemicals and prioritizing for 

risk management. 

Question V.A.2. How might the 

information on the properties and 

toxicity of chemicals generated by 

CompTox, ToxCast, and/or Tox21 be 

utilized by employers to identify 

chemical hazards and protect workers 

from these hazards? OSHA is also 

interested to hear from commenters who 

may currently make use of these data in 

their worker protection programs. 

3. Production and Use Data Under 

EPA’s Chemical Data Reporting Rule 

Under the EPA’s Chemical Data 

Reporting (CDR) Rule, issued in 2011, 

EPA collects screening-level, exposurerelated information on certain chemicals 

included on the Toxic Substances 

Control Act (TSCA) Chemical Substance 

Inventory and makes that information 

publicly available to the extent possible. 

The CDR rule amended the TSCA 

Inventory Update Reporting (IUR) rule 

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and significantly increased the type and 

amount of information covered entities 

are required to report. The 2012 

submissions included data on more 

chemicals and with more in-depth 

information on manufacturing 

(including import), industrial 

processing and use, and consumer and 

commercial use than data collected 

under the IUR in 2006 (U.S. EPA, 2013a; 

Ex. #1). 

The expanded reporting on chemical 

production and use information under 

the CDR could help OSHA better 

understand how workers are exposed to 

chemicals and the industries and 

occupations where exposures to 

chemicals might occur. 

4.Structure-Activity Data for Chemical 

Grouping 

Although toxicity testing for 

chemicals has increased greatly since 

the passage of the Toxic Substances 

Control Act (15 U.S.C. 2601–2629; Ex. 

#62) in the United States, and with 

similar legislation elsewhere, toxicity 

data is only publicly available for a 

fraction of industrial chemicals. Since 

the enactment of TSCA and creation of 

the TSCA Interagency Testing 

Committee (U.S. EPA, 2013c; Ex. #57), 

the ITC has recommended testing for 

hundreds of chemicals, and chemical 

producers have conducted more than 

900 tests for these chemicals. However, 

potentially thousands of industrial 

chemicals have not been tested. 

With the rapidly expanding 

development of new chemical 

substances and mixtures, the need for 

toxicity information to inform chemical 

safety management and public health 

decisions in a timely manner has 

exceeded the capacity of the 

government programs to provide those 

data. As a result, programs such as the 

Organization for Economic Cooperation 

and Development’s (OECD) Screening 

Information Data Set (SIDS) and the U.S. 

EPA High Production Volume (HPV) 

Challenge programs were designed to 

encourage the voluntary development of 

data. However, even with the creation of 

these non-statutory programs, 

potentially thousands of non-HPV 

industrial chemicals go untested. 

Therefore, chemical prioritization for 

screening and testing requires the 

development and validation of standard 

methods to predict the human and 

environmental effects and potential fate 

of chemicals. Where screening and 

testing data are sparse, the use of 

predictive models called structural 

activity relations (SARs) or quantitative 

structural activity relationships (QSARs) 

can extend the use of limited toxicity 

and safety data for some untested 

chemicals (Russom et al., 2003; Ex. 

#64). QSARs are mathematical models 

that are used to predict measures of 

toxicity from physical characteristics of 

the structure of chemicals, known as 

molecular descriptors. 

Other U.S. and international agencies 

have explored the use of chemical 

groupings to regulate chemicals in order 

to fulfill their regulatory and statutory 

authorities. Under the TSCA Work Plan, 

the EPA announced in 2013 that it 

would begin to assess 20 flame retardant 

chemicals and three non-flame retardant 

chemicals. EPA utilized a structurebased approach, grouping eight other 

flame retardants with similar 

characteristics together with the 

chemicals targeted for full assessment in 

three groupings. EPA will use the 

information from these assessments to 

better understand the other chemicals in 

the group, which currently lack 

sufficient data for a full risk assessment. 

EPA uses chemical groupings to fill 

data gaps in its New Chemical Program. 

EPA’s New Chemical Program, also 

under TSCA, requires anyone who plans 

to manufacture or import a new 

chemical substance into commerce to 

provide EPA with notice before 

initiating the activity. This is called a 

pre-manufacture notification (PMN). 

EPA received approximately 1,500 new 

chemical notices each year and has 

reviewed more than 45,000 from 1979 

through 2005 (GAO, 2007; Ex. #65). 

Because TSCA does not require testing 

before submission of a PMN, SARs and 

QSARs are often used to predict the 

environmental fate and ecologic effects. 

In addition, the EPA makes predictions 

concerning chemical identity, physical/ 

chemical properties, environmental 

transport and partitioning, 

environmental fate, environmental 

toxicity, engineering releases to the 

environment, and environmental 

concentrations. The agency uses a 

variety of methods to make these 

predictions that include SARs, nearestanalogue analysis, chemical class 

analogy, mechanisms of toxicity, and 

chemical industry survey data and the 

collective professional judgment of 

expert scientific staff, in the absence of 

empirical data. The agency uses these 

methods to fill data gaps in an 

assessment and to validate submitted 

data in notifications. Predictions are 

also made by the U.S. EPA Office of 

Pollution Prevention and Toxics (OPPT) 

under TSCA (Zeeman., 1995; Ex. #66). 

The OPPT has routinely used QSARs to 

predict ecologic hazards, fate, and risks 

of new industrial chemicals, as well as 

to identify new chemical testing needs, 

for more than two decades. OPPT SAR/ 

QSARs for physical/chemical properties 

used for new chemical assessments are 

publically available (U.S. EPA, 2012b; 

Ex. #67). 

In Europe, internationally agreedupon principles for the validation of 

(Q)SARs were adopted by OECD 

Member Countries and the Commission 

in 2004. In 2007, the Inter-organization 

Programme for the Sound Management 

of Chemicals, a cooperative agreement 

among United Nations Environmental 

Program (UNEP); International Labor 

Organization (ILO); Food and 

Agriculture Organization of the United 

Nations (FAO); World Health 

Organization (WHO); United Nations 

Industrial Development Organization 

(UNIDO), United Nations Institute for 

Training and Research (UNITAR) and 

Organization for Economic Co-operation 

and Development (OECD) published 

‘‘Guidance on Grouping of Chemicals’’ 

as part of an ongoing monograph series 

on testing chemicals. REACH registrants 

may rely on (Q)SAR data instead of 

experimental data, provided the 

registrants can provide adequate and 

reliable documentation of the applied 

method and document the validity of 

the model. Validation focuses on the 

relevance and reliability of a model 

(ECHA, 2008; Ex. #68). 

The EU Scientific Committee on 

Toxicity, Ecotoxicity and the 

Environment (CSTEE) recommended, in 

their general data requirements for 

regulatory submission, that QSAR data 

may be used as well as animal data. A 

chemical category approach based on 

the metal ion has been extensively used 

for the classification and labeling of 

metal compounds in the EU. Other 

category entries are based on certain 

anions of concern such as oxalates and 

thiocyanates. For these EU 

classifications the category approach 

has often been applied to certain 

endpoints of particular concern for the 

compounds under consideration, but 

has not necessarily been applied to all 

endpoints of each individual compound 

in the category of substances. 

The Danish EPA has made extensive 

use of QSARs and has developed a 

QSAR database that contains predicted 

data on more than 166,000 substances 

(OSPAR Commission, 2000; Ex. #69). A 

recent publication from the Danish EPA 

reports the use of QSARs for 

identification of potential persistent, 

bioaccumulative and toxic (PBT) and 

very persistent and very 

bioaccumulative (vPvB) substances from 

among the HPV and mediumproduction volume chemicals in the EU. 

OSHA is considering using a 

combination of chemical group 

approaches to evaluate multiple 

chemicals with similar attributes 

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utilizing limited data that can be 

extrapolated across categories. The 

Agency invites comment on how such 

grouping approaches have been used to 

evaluate risks to worker populations. 

Question V.A.3: Are QSAR, readacross, and trend analysis useful and 

acceptable methods for developing 

hazard information utilizing multiple 

data sets for a specific group of 

chemicals? 

Question V.A.4: Are there other 

acceptable methods that can be used to 

develop hazard information for multiple 

chemicals within a group? 

Question V.A.5: What are the 

advantages and disadvantages of each 

method? 

5. REACH: Registration, Evaluation, 

Authorization, and Restriction of 

Chemicals in the European Union (EU) 

Safe chemical management is a 

universal concern. The European Union, 

recognizing the need for a more 

integrated approach to chemical 

management, adopted REACH 

(Registration, Evaluation, Authorization, 

and Restriction of Chemicals) to address 

chemicals throughout their life cycle. 

Although REACH applies to European 

Union Member States, chemical 

manufacturers in other countries 

exporting to European countries also 

have to comply with the REACH 

requirements to sell their products in 

Europe. 

The REACH Regulation (EC) No 1907/ 

2006 became effective on June 1, 2007, 

and relies on the generation and 

disclosure of data by manufacturers and 

importers of chemicals in order to 

protect human health and the 

environment from chemical hazards. 

The regulation also established the 

European Chemicals Agency (ECHA) to 

coordinate implementation (EC 1907/

2006, 2006; Ex. #70). 

REACH establishes processes for the 

Registration, Evaluation, Authorization, 

and Restriction of Chemicals. REACH 

requires manufacturers and importers to 

register their chemicals and establish 

procedures for collecting and assessing 

information on the properties, hazards, 

potential risks and uses of their 

chemicals. The registration process, 

which began in 2010, is being phasedin based on the tonnage and hazard 

classification of the substances. For 

existing chemicals, it is set to be 

completed in June 2018. 

For each chemical manufactured or 

imported in quantities of 1 ton or more 

per year, companies must register the 

substance by providing a technical 

dossier to ECHA. The technical dossier 

includes information on: Substance 

identity; physicochemical properties; 

mammalian toxicity; ecotoxicity; 

environmental fate; manufacture and 

use; and risk management measures 

(ECHA, 2012b; Ex. #71). Nonconfidential information from the 

technical dossiers is published on the 

ECHA Web site (ECHA, 2012c; Ex. #72). 

Companies manufacturing or 

importing a chemical in quantities of 10 

or more tons per year must also conduct 

a chemical safety assessment. This 

assessment includes the evaluation of: 

(1) Human health hazards; (2) 

physicochemical hazards; (3) 

environmental hazards; and (4) 

persistent, bioaccumulative and toxic 

(PBT), and very persistent and very 

bioaccumulative (vPvB) potential 

(ECHA, 2012b; Ex. #71). If a substance 

is determined to be hazardous or a PBT/ 

vPvB, registrants must then conduct an 

exposure assessment, including the 

development of exposure scenario(s) 

(ES) and exposure estimation, and a risk 

characterization that includes 

development of a health effects 

benchmark, such as the Derived No 

Effect Level (DNEL). 

An exposure scenario, the main 

output of the exposure assessment 

process, documents a set of operational 

conditions and risk management 

measures for a specific use of a 

substance. A number of exposure 

estimation models have been developed 

in the EU to help the regulated 

community create these exposure 

scenarios. Exposure scenarios must also 

be included in the Safety Data Sheets 

(SDS) in order to communicate this 

information down the supply chain. 

When an extended SDS with exposure 

scenarios is received by a chemical user, 

the exposure scenarios must be 

reviewed to determine if they are 

applicable to the use situation in that 

facility. If the exposure scenarios are 

applicable, the user has 12 months to 

implement them. If they are not, the 

user has several options to choose from 

to determine appropriate controls. 

These options include: (1) User 

informing supplier of their use, and user 

convincing supplier to recognize it as an 

‘‘identified use’’ on suppliers safety 

assessment; (2) user implementing the 

suppliers conditions of use described in 

the exposure scenario of the original/

current safety assessment; (3) user 

substituting the substance for another 

substance that is covered in a preexisting safety assessment; (4) user 

finding another supplier who does 

provide an exposure scenario that 

covers the use of the substance; or (5) 

prepare a downstream user chemical 

safety report. (ECHA, 2012c; Ex. #72). 

After completing the exposure 

assessment, registrants conduct a risk 

characterization process to determine if 

the operational conditions cause 

exposures that require risk management 

measures to ensure risks of the 

substance are controlled. Risk 

characterization consists of the 

comparison of exposure values derived 

from each exposure scenario with their 

respective DNEL or an analogous health 

benchmark such as Derived Minimal 

Effect Level (DMEL) or Predicted No 

Effect Concentration (PNEC)), 

established by the registrant. Where no 

health benchmark is available, a 

qualitative risk characterization is 

required (ECHA, 2009; Ex. #73). 

Manufacturers and importers are 

required to document the information 

developed during the chemical safety 

assessment in a chemical safety report, 

which is submitted to ECHA. The report 

then forms the basis for other REACH 

processes, including substance 

evaluation, authorization, and 

restriction. 

ECHA and the EU Member States then 

evaluate the information submitted 

during the registration process to 

examine the testing proposals, check the 

quality of the registration dossiers, and 

evaluate whether a substance 

constitutes a risk to human health or the 

environment. Following the evaluation 

process, registrants may be required to 

comply with additional actions to 

address concerns (i.e., submit further 

information, proceed on restriction or 

authorization procedures under REACH, 

take actions under other legislation, 

etc.). (ECHA, 2012d; Ex. #74). 

As the implementation of REACH 

continues, large amounts of information 

will be generated by manufacturers, 

importers, and downstream users 

throughout the registration, 

authorization, and restriction processes. 

Some of this information is publicly 

available on ECHA Web sites, and 

includes toxicological information, 

general exposure control 

recommendations, and assessments of 

the availability of alternatives. The 

generation and availability of this 

extensive data on chemicals can assist 

OSHA, as well as U.S. employers and 

workers, to further enhance chemical 

safety and health management by 

assisting in the assessment of hazards, 

development of exposure control 

recommendations, and selection of 

substitutes to help drive the transition 

to safer chemicals in the workplace. 

As of July, 2013, the REACH database 

of registered substances is comprised of 

more than 9900 substances. The 

database provides extensive information 

to the public from dossiers prepared by 

chemical manufacturers, importers, and 

downstream users. OSHA is interested 

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in determining whether some 

information developed and submitted 

under REACH may be helpful to OSHA 

in its own regulatory initiatives. 

Information submitted under REACH’s 

requirements to assess chemical risks in 

workplaces may be useful in developing 

task-based exposure control plans, or of 

use in OSHA’s feasibility analyses. 

OSHA is participating in high-level 

discussions with the EU about the 

feasibility of sharing these data. 

Question V.A.6: OSHA is interested in 

the experiences of companies that have 

had to prepare chemical dossiers and 

submit registration information to the 

European Chemicals Agency (ECHA) 

ECHA. In particular, how might the 

approaches be used to support 

occupational exposure assessments and 

development of use-specific risk 

management in the United States? 

Question V.A.7: To what extent is 

information developed under REACH 

used by U.S. businesses to promote 

product stewardship and ensure safe 

use of substances and mixtures by 

product users? 

Question V.A.8: Should OSHA pursue 

efforts to obtain data from ECHA that 

companies are required to provide 

under REACH? 

B. Non-OEL Approaches to Chemical 

Management 

OSHA’s PELs and its corresponding 

hierarchy of controls have been a major 

focus in the fields of occupational 

health and industrial hygiene for many 

years. Undoubtedly, occupational 

exposure limits (OELs), which help 

reduce workers’ risk of adverse health 

by establishing precise targets for 

employers to follow, will always be an 

essential part of controlling chemical 

exposures in workplaces. However, 

regardless of whether a more effective 

process for updating OSHA’s PELs can 

be established, the rapid development of 

new chemical substances and mixtures 

that will continue to leave workers 

exposed to thousands of unregulated 

substances make it impractical to solely 

rely on OELs. Moreover, for many of the 

chemicals and mixtures that have been 

developed since the PELs were initially 

promulgated, insufficient hazard 

information exists to serve as a basis for 

developing OELs. While OELs generally 

focus on a single chemical, workers are 

typically exposed to mixtures or 

multiple substances in the workplace. 

Mixed exposures may also result in 

synergistic or antagonistic effects that 

are rarely considered in developing 

OELs. 

Workplace risk assessments, and 

corresponding risk management plans, 

should be based on an evaluation of all 

hazards present—OELs established for a 

few chemicals among the many in the 

workplace environment have 

diminished impact in these situations. 

Unlike OELs, which are only useful in 

protecting workers if regular 

measurement and assessment of 

compliance is completed, alternative 

risk management approaches focus more 

on determining what types of controls 

are required to reduce exposures 

without necessarily referring to 

quantitative assessments of exposure to 

evaluate success. 

An important aspect of risk 

assessment and risk management is 

consideration of safer alternatives, 

which can often result in a path forward 

that is less hazardous, technically 

feasible, and economically viable. 

1. Informed Substitution to Safer 

Chemicals and Processes 

While establishing exposure limits for 

hazardous chemicals helps to reduce 

workers’ risk of adverse health effects, 

the process is costly, time consuming, 

and does not drive the development or 

adoption of safer alternatives that could 

best protect workers. OSHA recognizes 

that ultimately, an approach to chemical 

management that incentivizes and spurs 

the transition to safer chemicals, 

products, and processes in a thoughtful, 

systematic way will most effectively 

ensure safe and healthful conditions for 

workers. 

Informed substitution, the considered 

transition from hazardous chemicals to 

safer substances or non-chemical 

alternatives, provides a way of moving 

toward a more preventative chemical 

management framework. 

a. Substitution in Practice 

Whenever a hazardous chemical is 

regulated, there is always the potential 

for the chemical to be replaced with a 

substitute chemical or redesigned 

product or process that poses new and 

potentially greater hazards to workers, 

consumers, or the environment or 

results in risk-shifting from one group to 

another. Regrettably, this potential has 

been realized in a number of cases. For 

example: 

• The regulation of methylene 

chloride by EPA, FDA, and OSHA 

spurred the shift to 1-bromopropane, an 

unregulated neurotoxicant and possible 

carcinogen, in a variety of applications, 

such as refrigeration, metal cleaning, 

and vapor and immersion degreasing 

applications, as well as in adhesive 

resins (Kriebel et al., 2011; Ex. #75). 

• Air quality regulations in California 

created a market in the vehicle repair 

industry for solvent products 

formulated with n-hexane, a 

neurotoxicant causing symptoms of 

peripheral neuropathy, and hexaneacetone blends, which amplify the 

neurotoxic effects of n-hexane, thus 

resulting in risk-shifting from the 

environment to workers (Wilson et al., 

2007; Ex. #76). 

While regulatory processes lacking a 

robust assessment of alternatives can 

result in substitution that is equally 

detrimental to human health or the 

environment, regulatory efforts that 

require planning processes and provide 

guidance and technical assistance on 

preferred alternatives can minimize risk 

trade-offs and protect workers, 

consumers, and the environment. For 

example, in Massachusetts, facilities 

using specific toxic chemicals in certain 

quantities are required to undertake a 

toxics use reduction planning process. 

Agencies provide various resources to 

encourage and facilitate the voluntary 

adoption of alternatives. In the case of 

trichloroethylene, the Massachusetts 

Office of Technical Assistance and the 

Toxics Use Reduction Institute provided 

technical assistance, educational 

workshops, a database of safer 

alternatives, and performance 

evaluations of alternatives (Toxics Use 

Reduction Institute, 2011a; Ex. #78; 

Toxics Use Reduction Institute, 2011b; 

Ex. #79; Toxics Use Reduction Institute, 

2011c; Ex. #80). Through these efforts, 

Massachusetts companies reduced the 

use of trichloroethylene by 77 percent 

since 1990, moving to a number of safer 

alternatives in the process (Toxics Use 

Reduction Institute, 2011d; Ex. #81). 

These cases demonstrate that the 

transition to safer chemicals, materials, 

products, and processes will be best 

facilitated not through restrictions or 

bans of chemicals, but rather through 

the integration of informed substitution 

and guidance on preferred alternatives 

into regulatory efforts. 

b. Benefits of a Preference for Primary 

Prevention Strategies 

The reduction or elimination of a 

hazard at the source, as traditionally 

embraced by health and safety 

professionals, is not only the most 

reliable and effective control approach, 

but also provides a number of benefits 

for workers and businesses. 

Preferring primary prevention 

strategies (i.e. elimination and 

substitution) can result in the ‘‘total 

elimination of exposure to hazardous 

chemicals, less reliance on worker 

compliance or equipment maintenance 

for success, elimination of the potential 

for accidental or non-routine 

overexposures, prevention of dermal 

exposures, and process and 

environmental improvements not 

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related to worker health’’ (Roelofs et al., 

2003; Ex. #82). 

Additionally, making process 

improvements designed to reduce or 

eliminate workers’ exposures to 

hazardous chemicals often results in 

significant business improvements or 

savings. A 2008 study by the American 

Industrial Hygiene Association (AIHA) 

demonstrated the relationship between 

the application of the hierarchy of 

controls and financial benefits. The 

study found that the greatest cost 

savings and other benefits tended to be 

associated with hazard elimination and 

the elimination of personal protective 

equipment (PPE) usage. It also 

highlighted the ability of material 

substitution to result in very large 

payoffs due to the creation of 

efficiencies throughout the business 

process (American Industrial Hygiene 

Association, 2008; Ex. #83). For 

example: 

• A foundry making automatic diesel 

engine blocks enhanced and 

aggressively enforced a purchasing 

specification program to eliminate 

supplied scrap metal contaminated with 

lead. By eliminating lead from its 

supply chain, the company not only 

achieved high levels of employee 

protection, but also enhanced the 

quality of its products and realized 

nearly $20 million in savings for the 

facility. 

• An aircraft manufacturing 

company, struggling to comply with the 

OSHA PEL for hexavalent chromium, 

transitioned from chromate-based 

primers to non-chromate based primers, 

resulting not only in the elimination of 

worker exposure to chromate dusts from 

rework sanding, but also in quality 

improvements of its products, increased 

customer satisfaction, productivity 

gains, avoidance of costly changes to 

their exhaust ventilation system, and a 

savings of $504,694 over the 5-year 

duration of the project. 

c. Informed Substitution 

In order to truly protect workers from 

chemical hazards, it is important that 

OSHA not only develop health 

standards for hazardous chemicals, but 

also understand alternatives to regulated 

chemicals and support a path forward 

that is less hazardous, technically 

feasible, and economically viable. 

Informed substitution provides a 

framework for meeting this goal. 

As previously described, informed 

substitution is the considered transition 

from a potentially hazardous chemical, 

material, product, or process to safer 

chemical or non-chemical alternatives. 

The goals of informed substitution are to 

minimize the likelihood of unintended 

consequences, which can result from a 

precautionary switch away from a 

hazardous chemical without fully 

understanding the profile of potential 

alternatives, and to enable a course of 

action based on the best information 

that is available or can be estimated. 

Informed substitution approaches focus 

on identifying alternatives and 

evaluating their health, safety, and 

environmental hazards, potential tradeoffs, and technical and economic 

feasibility. 

Substitution is not limited to 

substitution of one chemical with 

another. It can also occur at the 

production process or product level. At 

the product level, substitution may 

involve a design change that takes 

advantage of the characteristics of new 

or different materials. A chemical 

process design change may eliminate 

several production steps thereby 

avoiding or reducing the use of high 

hazard chemicals. In some cases, a 

particular chemistry or the function it 

serves may be determined to be 

unnecessary. 

As implementation of chemical 

substitution and product and process 

changes can be quite complicated, a 

variety of processes, tools, and methods 

are critical to achieving informed 

substitution. 

Substitution planning, similar to 

facility planning for pollution 

prevention and source reduction, 

establishes practical steps for evaluating 

substitution as a workplace risk 

reduction measure. This type of 

planning process supports informed 

substitution by encouraging chemical 

users to: Systematically identify 

hazardous chemicals; set goals and 

priorities for the elimination or 

reduction of hazardous chemicals; 

evaluate alternatives; identify preferred 

alternatives; and promote the adoption 

of identified alternatives. 

Alternatives assessment is a process 

of identifying and comparing potential 

chemical and non-chemical alternatives 

that could replace chemicals or 

technologies of concern on the basis of 

their hazards, performance, and 

economic viability. A variety of 

alternatives assessment processes have 

been developed to date (Lavoie et al., 

2010; Ex. #84; Toxics Use Reduction 

Institute, 2006; Ex. #85; Rossi et al., 

2006; Ex. #86; Raphael et al., 2011; Ex. 

#87). Various tools and methods have 

been developed to evaluate hazard, 

performance, and cost when assessing 

alternatives. For example, comparative 

chemicals hazard assessments compare 

potential alternatives based on a variety 

of hazard endpoints in order to select a 

safer alternative. Some examples of 

comparative chemicals hazard 

assessment tools include the 

GreenScreen (Clean Production Action, 

2012; Ex. #88) and Design for the 

Environment (DfE) Safer Product 

Labeling Program (U.S. EPA, 2011a; Ex. 

#89). Other existing methods for 

chemical comparison include the 

Column Model (Institut fu ̈r 

Arbeitsschutz der Deutschen 

Gesetzlichen Unfallversicherung, 2011; 

Ex. #90) and QuickScan (Netherlands 

Ministry of Infrastructure and the 

Environment, 2002; Ex. #91). Tools and 

methods for evaluating performance and 

cost attributes, while less well 

developed, are also critical for the 

selection of a preferred alternative. 

d. Substitution at OSHA 

Substitution is not new for OSHA. 

Historically, OSHA attempted to 

encourage substitution by setting a ‘‘no 

occupational exposure level’’ for certain 

potential carcinogens where suitable 

substitutes that are less hazardous to 

humans existed for particular uses (45 

FR 5257–58; Ex. #92). Although this 

requirement was never fully 

implemented, the final rule detailed a 

process for the Agency to analyze the 

feasibility of substitutes, which required 

the consideration of: (1) the safety of the 

substitute, including the comparative 

acute and chronic toxicity of the 

carcinogenic chemical and the 

substitute, and other relevant factors, 

such as environmental factors; (2) the 

technical feasibility of the substitute, 

including its relative effectiveness; and 

(3) the economic cost of substitution (45 

FR 5258; Ex. #92, 29 CFR 1990.111(k); 

Ex. #93, see also 1990.132(b)(6); Ex. #94, 

1990.146(k); Ex. #95). 

OSHA health standards also identify 

substitution as a preferred exposure 

control. For example, in the 1989 Air 

Contaminants Standard, the Agency 

refers to substitution, when properly 

applied, as ‘‘a very effective control 

technique’’ and ‘‘the quickest and most 

effective means of reducing exposure’’ 

(54 FR 2727, 2789; Ex. #7). In addition, 

the Agency’s respiratory protection 

standard mandates the use of accepted 

engineering control measures, including 

the substitution of less toxic materials, 

as far as feasible, before using 

respirators to control occupational 

diseases caused by breathing 

contaminated air (29 CFR 1910.134(a); 

Ex. #96). Despite this, when complying 

with PELs and other health standards in 

practice, employers are required to 

select and implement administrative or 

engineering controls before using 

personal protective equipment, but are 

not specifically required or encouraged 

to consider elimination or substitution 

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before other engineering or 

administrative controls. (See 29 CFR 

1910.1000(e); Ex. #97). Thus, 

substitution may be often overlooked in 

favor of other approaches, such as 

ventilation and isolation, when 

employers are controlling exposures to 

hazardous chemicals. 

OSHA also considers substitution 

during the development of PELs. While 

OSHA does not solely rely on 

substitution to make its required 

feasibility findings (62 FR 1494, 1576; 

Ex. #98; 71 FR 10099, 10260; Ex. #99), 

the Agency, as part of PEL rulemaking 

efforts, develops and evaluates 

information about substitution in its 

technological and economic feasibility 

analysis, highlighting options available 

for eliminating or reducing the regulated 

chemical’s use in various industries and 

applications. For example, the 

feasibility analysis for methylene 

chloride describes numerous substitute 

chemicals and processes, including a 

detailed table of substitute paint 

removal methods for 16 applications, 

and evaluates the relative risks for seven 

of the more common substitutes for 

methylene chloride (OSHA, 1996; Ex. 

#100). However, the analysis of 

substitutes has varied widely from 

regulation to regulation. For example, 

the feasibility analysis for hexavalent 

chromium identifies specific substitute 

chemicals and processes in many 

industries, but does not discuss the 

health or safety hazards of the 

substitutes (OSHA, 2006a; Ex. #101), 

while the feasibility analysis for 

formaldehyde includes only a mention 

of the availability of one identified 

substitute for a few industry sectors 

(OSHA, 1987; Ex. #102) and the 

feasibility analysis for ethylene oxide 

does not contain any discussion of 

substitutes (OSHA, 1984; Ex. #103). 

OSHA has also included information 

on substitutes in a variety of nonregulatory documents. New information 

about available substitutes and 

substitution trends is included in 

lookback reviews of existing standards 

conducted by the Agency (e.g., lookback 

review of the ethylene oxide standard, 

lookback review of the methylene 

chloride standard) (OSHA, 2005; Ex. 

#104; OSHA, 2010; Ex. #105). In some 

cases, OSHA has also developed 

information on substitution, even where 

a PEL has not been established. For 

example, the OSHA guidance document 

on the best practices for the safe use of 

glutaraldehyde in health care includes 

information about drop-in replacements 

and alternative processes available to 

reduce or eliminate the use of the 

chemical (OSHA, 2006b; Ex. #106). 

In October 2013, OSHA launched an 

effort to encourage employers, workers, 

and unions to proactively reduce the 

use of hazardous chemicals in the 

workplace and achieve chemical use 

that is safer for workers and better for 

business. As part of this effort, the 

Agency developed a web toolkit that 

guides employers and workers in any 

industry through a seven-step process 

for transitioning to safer chemicals 

(OSHA, 2013a; Ex. #107). Each step 

contains information, resources, 

methods, and tools that will help users 

eliminate hazardous chemicals or make 

informed substitution decisions in the 

workplace by finding a safer chemical, 

material, product, or process. 

e. Possible Opportunities for Integrating 

Informed Substitution Approaches Into 

OSHA Activities 

There are a variety of existing 

regulatory and non-regulatory models 

for incorporating informed substitution 

into chemical management activities. 

The following are some examples of 

entities that have developed and 

utilized informed substitution 

approaches as part of regulatory efforts; 

guidance and policy development; 

education, training, and technical 

assistance activities; and data 

development and research efforts. 

i. Models for Regulatory Approaches 

Some regulations and voluntary 

standards require risk reduction through 

the implementation of a hierarchy of 

controls that clearly delineates 

elimination and substitution as 

preferred options to be considered and 

implemented, where feasible, before 

other controls. For example, the ANSI/ 

AIHA Z10–2005 standard for 

Occupational Health and Safety 

Management Systems, a voluntary 

national consensus standard, requires 

organizations to implement and 

maintain a process for achieving feasible 

risk reduction based upon the following 

preferred order of controls: A. 

Elimination; B. Substitution of less 

hazardous materials, processes, 

operations, or equipment; C. 

Engineering controls; D. Warnings; E. 

Administrative Controls; and F. 

Personal protective equipment (ANSI/

AIHA Z10–2005, 2005; Ex. #108). 

European Union Directives 98/24/EC 

and 2004/37/EC require employers to 

eliminate risks by substitution before 

implementing other types of protection 

and prevention measures (98/24/EC, 

1998; Ex. #109, 2004/37/EC, 2004; Ex. 

#110). 

Some existing laws require firms to 

undertake planning processes for the 

reduction of identified hazardous 

chemicals. For example, the 

Massachusetts Toxics Use Reduction 

Act requires entities that use listed 

hazardous chemicals in certain 

quantities to undertake a planning 

process for reducing the use of those 

chemicals (Massachusetts Department of 

Environmental Protection, n.d.; Ex. 

#77). 

Existing regulations in the European 

Union place a duty on employers to 

replace the use of certain hazardous 

chemicals with safer substitutes, if 

technically possible. For example, 

Directive 2004/37/EC requires the 

substitution of carcinogens and 

mutagens with less harmful substances 

where technically feasible (2004/37/EC, 

2004) and Directive 98/24/EC requires 

employers to ensure that risks from 

hazardous chemical agents are 

eliminated or reduced to a minimum, 

preferably by substitution (98/24/EC, 

1998; Ex. #109). 

Other regulations require the use of 

acceptable substitutes where the uses of 

certain hazardous chemicals are phasedout. This type of approach is currently 

implemented by U.S. EPA in the context 

of phasing-out ozone depleting 

substances. The Clean Air Act requires 

that these substances be replaced by 

others that reduce risks to human health 

and the environment. Under the 

Significant New Alternatives Policy 

(SNAP) program, EPA identifies and 

publishes lists of acceptable and 

unacceptable substitutes for ozonedepleting substances (Safe Alternatives 

Policy, 2011; Ex. #111). 

Some chemical management 

frameworks require the assessment of 

substitutes before making decisions to 

limit or restrict the use of a hazardous 

chemical. For example, the European 

Union REACH Regulation (Registration, 

Evaluation, Authorization and 

Restriction of Chemicals) requires that 

an analysis of alternatives, the risks 

involved in using any alternative, and 

the technical and economic feasibility of 

substitution be conducted during 

applications of authorization for 

substances of very high concern (EC 

1907/2006, 2006; Ex. #70). 

Other efforts to spur the transition to 

safer chemicals, products, and processes 

are based on the development of 

criteria-based standards for functions or 

processes that rely on hazardous 

chemicals. For example, the EPA DfE 

Safer Product Labeling Program is a 

nonregulatory program that recognizes 

safe products using established criteriabased standards. In order to receive DfE 

recognition, all chemicals in a 

formulated product must meet Master 

Criteria (i.e., toxicological thresholds for 

attributes of concern, including: acute 

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mammalian toxicity; carcinogenicity; 

genetic toxicity; neurotoxicity; repeated 

dose toxicity; reproductive and 

developmental toxicity; respiratory 

sensitization; skin sensitization; 

environmental toxicity and fate; and 

eutrophication), as well as relevant 

functional-class criteria (i.e., additional 

toxicological thresholds for attributes of 

concern for surfactants, solvents, directrelease products, fragrances, and 

chelating and sequestering agents), 

established by the EPA (U.S. EPA, 

2011a; Ex. #89). 

While there are a number of ways in 

which OSHA could consider integrating 

substitution and alternatives assessment 

into its regulatory efforts, the Agency, in 

order to promulgate any such standard, 

would need to make the significant risk, 

technological feasibility, and economic 

feasibility findings required under the 

OSH Act. However, even without 

regulation, it is important to consider 

voluntary models for incorporating 

informed substitution into chemical 

management activities. 

ii. Models for Guidance Development 

Some entities have developed 

guidance to promote the transition to 

safer alternatives. The European Union, 

in order to support legislative 

substitution mandates, developed 

guidance on the process of substitution, 

including setting goals, identifying 

priority chemicals, evaluating 

substitutes, selecting safer alternatives, 

and implementing chemical, material, 

and process changes. The guidance 

establishes and describes a seven step 

substitution framework, providing 

workplaces with a systematic process 

for evaluating chemical risk and 

identifying chemicals that could or 

should be substituted (European 

Commission, 2012; Ex. #113). The steps 

include: Assessing the current level of 

risk; deciding on risk reduction needs; 

assessing the margins of change; looking 

for alternatives; checking the 

consequences of a change; deciding on 

change; and deciding on how and when 

to implement change. 

Similarly, the German Federal 

Institute for Occupational Safety and 

Health (BAuA) established guidance to 

support the employer’s duty, as 

mandated in the German Hazardous 

Substances Ordinance, to evaluate 

substitutes to hazardous substances and 

implement substitution where less 

hazardous alternatives are identified 

(German Federal Institute for 

Occupational Safety and Health, 2011; 

Ex. #114). The guidance, TRGS 600, 

includes a framework for identifying 

and evaluating substitutes and 

establishes criteria for assessing and 

comparing the health risks, 

physicochemical risks, and technical 

suitability of identified alternatives 

(German Federal Institute for 

Occupational Safety and Health, 2008; 

Ex. #115). 

The German Environment Agency has 

also developed guidance on sustainable 

chemicals. The guide assists 

manufacturers, formulators, and end 

users of chemicals in the selection of 

sustainable chemicals by providing 

criteria to distinguish between 

sustainable and non-sustainable 

substances (German Environment 

Agency, 2011; Ex. #116). 

OSHA considered developing 

guidance on safer substitutes to 

accompany individual chemical 

exposure limit standards in its 2010 

regulatory review of methylene 

chloride. Due to the increased use of 

other hazardous substitutes after 

methylene chloride was regulated in 

1998, the Agency considered 

establishing guidance recommending 

that firms check the toxicity of 

alternatives on the EPA and NIOSH Web 

sites before using a substitute (OSHA, 

2010; Ex. #105). 

iii. Models for Education, Training, and 

Technical Assistance 

Other entities have developed 

outreach, training, and technical 

assistance efforts for substitution 

planning and the assessment of 

substitutes for regulated chemicals. The 

Massachusetts Toxics Use Reduction 

Act, which established a number of 

structures to assist businesses, provides 

a good example of such efforts. The 

Massachusetts Office of Technical 

Assistance and Technology (OTA) 

provides compliance assistance and onsite technical support that helps 

facilities use less toxic processes and 

boost economic performance. The 

Massachusetts Toxics Use Reduction 

Institute provides training, conducts 

research, and performs alternatives 

assessments in order to educate 

businesses on the existence of safer 

alternatives and promote the on-theground adoption of these alternatives. 

Toxics Use Reduction Planners 

(TURPs), certified by the Massachusetts 

Department of Environmental Protection 

(MA DEP), prepare, write and certify the 

required toxics use reduction plans and 

are continually educated about best 

practices in toxics use reduction. Taken 

together, these services provide a robust 

resource for regulated businesses on the 

transition to safer alternatives 

(Massachusetts Department of 

Environmental Protection, n.d.; Ex. 

#77). 

iv. Models for Data Development 

Several efforts, at both the federal and 

international levels, attempt to support 

the transition to safer alternatives 

through research and data development. 

For example, EPA, in collaboration with 

the non-governmental organization 

GreenBlue and industry stakeholders, 

jointly developed a database of cleaning 

product ingredient chemicals 

(surfactants, solvents, fragrances, and 

chelating agents) that meet identified 

environmental and human health 

criteria (GreenBlue, 2012; Ex. #117). In 

Spain, the Institute of Work, 

Environment, and Health (ISTAS) has 

developed a database that is a repository 

of information on substitute chemicals. 

The database can be searched for 

chemical substances, uses/products, 

processes, or sectors to display 

information on substitutes and hazards 

associated with those substitutes 

(ISTAS, 2012; Ex. #118). In addition, the 

European Union SUBSPORT project has 

begun to create a Substitution Support 

Portal, a state-of-the-art resource on 

safer alternatives to the use of hazardous 

chemicals. The resource is intended to 

provide not only information on 

alternative substances and technologies, 

but also tools and guidance for 

substance evaluation and substitution 

management (SUBSPORT, 2012; Ex. 

#119). 

Other efforts focus on the completion 

of alternatives assessments for priority 

chemicals and uses. Currently, EPA’s 

Design for the Environment Program, as 

well as the Massachusetts Toxics Use 

Reduction Institute, has conducted 

alternatives assessments for priority 

chemicals and functional uses, making 

this information publicly available in 

the process (U.S. EPA, 2012c; Ex. #120; 

Toxics Use Reduction Institute, 2006; 

Ex. #85). 

In addition, some research efforts 

attempt to fill data gaps with regards to 

the toxicological properties of existing 

chemicals. While some efforts to 

conduct toxicity testing for chemicals is 

taking place at the federal level (U.S. 

EPA, 2011b; Ex. #121, U.S. EPA, 2012d; 

Ex. #122), there have not been 

systematic efforts to conduct targeted 

toxicology studies for specific 

substitutes of interest. 

Question V.B.1: To what extent do 

you currently consider elimination and 

substitution for controlling exposures to 

chemical hazards? 

Question V.B.2: What approaches 

would most effectively encourage 

businesses to consider substitution and 

adopt safer substitutes? 

Question V.B.3: What options would 

be least burdensome to industry, 

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especially small businesses? What 

options would be most burdensome? 

Question V.B.4: What information and 

support do businesses need to identify 

and transition to safer alternatives? 

What are the most effective means to 

provide this information and support? 

Question V.B.5: How could OSHA 

leverage existing data resources to 

provide necessary substitution 

information to businesses? 

v. Effectively Implementing Informed 

Substitution Approaches 

The goals of informed substitution 

cannot be achieved without the 

development and application of tools 

and methods for identifying, comparing, 

and selecting alternatives. Existing tools 

and methods range in complexity, from 

quick screening tools to detailed 

comparative hazard assessment 

methodologies to robust frameworks for 

evaluating alternatives based on hazard, 

performance, and economic feasibility. 

Illustrative examples, which represent 

the range of tools available, are 

described below. 

Some assessment tools provide 

methods for rapid evaluation of 

chemical hazards based on readily 

available information. These types of 

tools are critical for small and mediumsized businesses, which often lack 

resources and expertise to evaluate and 

compare chemical hazards. In the state 

of Washington, the Department of 

Ecology (DOE) has developed the Quick 

Chemical Assessment Tool (QCAT) to 

allow businesses to identify chemicals 

that are not viable alternatives to a 

chemical of concern by assigning an 

appropriate grade for the chemical 

based on nine high priority hazard 

endpoints (Washington Department of 

Ecology, 2012; Ex. #123). Similarly, the 

Institute for Occupational Safety and 

Health of the German Federation of 

Institutions for Statutory Accident 

Insurance and Prevention (IFA) 

developed the Column Model as a tool 

for businesses to evaluate chemicals 

based on six hazard categories using 

information obtained from chemical 

safety data sheets (IFA, 2011; Ex. #90). 

Other existing tools provide more 

detailed methodologies for conducting a 

comparative hazard assessment, which 

require greater expertise, data, and 

resources to complete. The 

GreenScreen, created by Clean 

Production Action, provides a 

methodology for evaluating and 

comparing the toxicity based on 

nineteen human and environmental 

hazard endpoints, assigning a level of 

concern of high, moderate, or low for 

each endpoint based on various 

established criteria (Clean Production 

Action, 2012; Ex. #88). 

A number of robust frameworks have 

also been developed to assess the 

feasibility of adopting alternatives for 

hazardous chemicals based on 

environmental, performance, economic, 

human health, and safety criteria. The 

Massachusetts Toxics Use Reduction 

Institute developed and implemented a 

methodology for assessing alternatives 

to hazardous chemicals based on 

performance, technical, financial, 

environmental, and human health 

parameters (TURI, 2006; Ex. #85). 

Similarly, the U.S. EPA DfE program has 

also developed and implemented an 

alternatives assessment framework to 

characterize alternatives based on the 

assessment of chemical hazards as well 

as the evaluation of availability, 

functionality, economic, and life cycle 

considerations (Lavoie et al., 2010; Ex. 

#84, U.S. EPA, 2012c; Ex. #120). 

Although some tools and methods 

exist, as discussed above, further 

research and development in this area is 

critical for the effective implementation 

of informed substitution. 

Question V.B.6: What tools or 

methods could be used by OSHA and/ 

or employers to conduct comparative 

hazard assessments? What criteria 

should be considered when comparing 

chemical hazards? 

Question V.B.7: What tools or 

methods could be used by OSHA and/ 

or employers to evaluate and compare 

the performance and cost attributes of 

alternatives? What criteria should be 

considered when evaluating 

performance and cost? 

2. Hazard Communication and the 

Globally Harmonized System (GHS) 

OSHA promulgated its Hazard 

Communication Standard (HCS) (29 

CFR 1910.1200; Ex. #124) in 1983 to 

require employers to obtain and provide 

information to their employees on the 

hazards associated with the chemicals 

used in their workplaces. After thirty 

years of implementation, the HCS has 

resulted in extensive information being 

disseminated in American workplaces 

through labels on containers, safety data 

sheets (SDSs), and worker training 

programs. 

On March 26, 2012, OSHA published 

major modifications to the HCS. (77 FR 

17574–17896; Ex. #125). These 

modifications are being phased in over 

several years, and will be completely 

implemented in June 2016. Referred to 

as HazCom 2012, the revised rule 

incorporates a new approach to 

assessing the hazards of chemicals, as 

well as conveying information about 

them to employees. The revised rule is 

based on the United Nations’ Globally 

Harmonized System for the 

Classification and Labeling of Chemicals 

(GHS), which established an 

international, harmonized approach to 

hazard communication. 

The original HCS was a performanceoriented rule that prescribed broad rules 

for hazard communication but allowed 

chemical manufacturers and importers 

to determine how the information was 

conveyed. In contrast, HazCom 2012 is 

specification-oriented. Thus, while the 

HCS requires chemical manufacturers 

and importers to determine the hazards 

of chemicals, and prepare labels and 

safety data sheets (SDSs), HazCom 2012 

goes further by specifying a detailed 

scheme for hazard classification and 

prescribing harmonized hazard 

information on labels. In addition, SDSs 

must follow a set order of information, 

and the information to be provided in 

each section is also specified. 

Hazard classification means that a 

chemical’s hazards are not only 

identified, they are characterized in 

terms of severity of the effect or weight 

of evidence for the effect. Thus, the 

assessment of the hazard involves 

identifying the ‘‘hazard class’’ into 

which a chemical falls (e.g., target organ 

toxicity), as well as the ‘‘hazard 

category’’—a further breakdown of the 

hazardous effect generally based on 

either numerical cut-offs, or an 

assessment of the weight of the 

evidence. For target organ toxicity, for 

example, chemicals for which there is 

human evidence of an effect are likely 

to be classified under Category 1, the 

most hazardous category, thus 

indicating the highest classification for 

the effect. If the only data available are 

animal studies, the chemical may fall in 

Category 2—still potentially hazardous 

to humans, but lower in terms of the 

weight of evidence for the effect. TableI illustrates how such a chemical hazard 

classification may be assigned by hazard 

class and hazard category 

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The process of classifying chemicals 

under HazCom 2012 means that all 

chemicals will be fully characterized as 

to their hazards, as well as degree of 

hazardous effect, using a standardized 

process with objective criteria. Thus, 

OSHA could use this system to select 

certain hazard classes and categories to 

set priorities. For example, the Agency 

could decide to identify substances that 

are characterized as Class 1 Carcinogens 

or as Reproductive Toxicants as its 

priorities. Then chemicals that fall into 

those hazard categories could be further 

investigated to determine other relevant 

factors, such as numbers of employees 

exposed, use of the chemical, risk 

assessment, etc. The HazCom 2012 

information could lead to a more 

structured and consistent priority 

system than previously attempted 

approaches. (Ex. #126) OSHA could also 

investigate whether the hazard 

categories lend themselves to 

establishing regulatory provisions for 

hazard classes and categories rather 

than for individual substances. The 

availability of specific hazard 

categorization for chemicals could allow 

this to be done on a grouping basis— 

either in regulation, or in guidance. 

Once a chemical is placed into a 

hazard class and hazard category, 

HazCom 2012 (and the GHS) specifies 

the harmonized information that must 

appear on the label. Referred to as ‘‘label 

elements,’’ these include a pictogram, 

signal word, hazard statement(s), and 

precautionary statement(s). In addition, 

the label must have a product identifier 

and supplier contact information. The 

use of standardized label elements will 

help to ensure consistency and 

comprehensibility of the information, 

which will make HazCom 2012 more 

effective in terms of conveying 

information to employees and 

employers. The approach taken in the 

GHS strengthens the protections of the 

OSHA HCS in several ways, and 

introduces the possibility of the Agency 

using the information generated under 

HazCom 2012 to help frame a more 

comprehensive approach to ensuring 

occupational chemical safety and 

health. 

3. Health Hazard Banding 

‘‘Health hazard banding’’ can be 

defined as a qualitative framework to 

develop occupational hazard 

assessments given uncertainties caused 

by limitations in the human health or 

toxicology data for a chemical or other 

agent. Health hazard banding presumes 

it is possible to group chemicals or other 

agents into categories of similar toxicity 

or hazard characteristics. 

Health hazard banding assigns 

chemicals with similar toxicities into 

hazard groups (or bands. The 

occupational health professional can 

use this classification or hazard band, 

along with information on worker 

exposures to the substance, to do 

exposure risk assessment. Hazard 

banding, along with exposure 

information, is a useful risk assessment 

tool, particularly in situations where 

toxicity data are sparse. Hazard banding 

can also aid in the prioritization and 

hazard ranking of chemicals in the 

workplace. NIOSH is working with 

OSHA and a variety of stakeholder 

groups (federal agencies, industry, labor 

organizations, and professional 

associations) to develop guidance on 

establishing the technical criteria, 

decision logic, and minimum dataset for 

the hazard band process. 

4. Occupational Exposure Banding 

NIOSH has proposed an approach, 

occupational exposure banding, which 

would sort chemicals into five bands (A 


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through E), with each band representing 

a different hazard level. Chemicals with 

the lowest toxicity would be grouped in 

Band A, while the moist toxic chemicals 

would be grouped in Band E. The 

proposed process includes a three-tiered 

evaluation system based on the 

availability of toxicological data to 

define a range of concentrations for 

controlling chemical exposures. A Tier 

1 evaluation relies on hazard codes and 

categories from GHS, and intended for 

chemicals for which little information 

exists. Therefore, a chemical in Band D 

or E in the Tier 1 process is a bad actor 

and should be targeted for elimination 

and or substitution. Tier 2 and 3 require 

professional expertise. Once NIOSH 

completes their validation work of the 

three tiers, they plan to develop tools to 

facilitate evaluating hazard data and 

assigning chemicals to hazard bands as 

well as educational materials for health 

and safety professionals, managers, and 

workers. (Exs. #127 & #128) 

5. Control Banding 

Control banding is a well-established 

approach of using the hazard statements 

from a label and/or safety data sheet 

(SDS) to lead an employer to 

recommended control measures. This 

approach has been used successfully in 

a number of countries, particularly in 

Europe where such as system of hazard 

classification has been in use for some 

time. HazCom 2012 opens up the 

possibility that control banding can be 

further developed and refined in the 

U.S., either as guidance or regulatory 

provisions. It is a particularly useful 

way to provide information for small 

businesses to effectively control 

chemicals without necessarily going 

through the process of exposure 

monitoring and other technical 

approaches to ensuring compliance. It 

also will give employers better 

information to conduct risk assessments 

of their own workplaces, and thus select 

better control measures. 

Health hazard banding can be used in 

conjunction with control banding to use 

the information available on the hazard 

to guide the assessment and 

management of workplace risks. In fact, 

health hazard banding is the first step in 

the control banding process. Control 

banding determines a control measure 

(for example dilution ventilation, 

engineering controls, containment, etc.) 

based on a range or ‘‘band’’ of hazards 

(such as skin/eye irritant, very toxic, 

carcinogenic, etc.), and exposures 

(small, medium, or large exposure). This 

approach is based on the fact that there 

are a limited number of control 

approaches, and that many chemical 

exposure problems have been met and 

solved before. Control banding uses the 

solutions that experts have developed 

previously to control occupational 

chemical exposures, and suggests them 

for other tasks with similar exposure 

situations. It focuses resources on 

exposure controls, and describes how 

strictly a risk needs to be managed. 

Control banding is a more 

comprehensive qualitative risk 

characterization and management 

strategy that goes further in assigning 

prescribed control methods to address 

chemical hazards. It is designed to allow 

employers to evaluate the need for 

exposure control in an operation and to 

identify the appropriate control strategy 

given the severity of the hazard present 

and magnitude of exposure. The 

strength of control banding is that it is 

based on information readily available 

to employers on safety data sheets 

(SDSs), without the need for exposure 

measurements or access to occupational 

health expertise (except in certain 

circumstances). Control banding 

involves not only the grouping of 

workplace substances into hazard bands 

(based on combinations of hazard and 

exposure information) but also links the 

bands to a suite of control measures, 

such as general dilution ventilation, 

local exhaust ventilation, containment, 

and use of personal protective 

equipment (PPE). 

Under control banding, one must 

consider the chemical’s hazardous 

properties, physical properties, and 

exposure potential in order to determine 

the level of exposure control desired. 

The criteria used for categorizing 

chemicals include hazard information 

such as flammability, reactivity, and the 

nature of known health effects. These 

characteristics are associated with 

defined hazard phrases (e.g., ‘‘Causes 

severe skin burns and eye damage’’ or 

‘‘Causes liver damage,’’ or 

‘‘Reproductive hazard’’). These 

standardized phrases have been familiar 

in the EU as ‘‘R-phrases’’ and are found 

on SDSs. 

Different hazard bands exist along a 

continuum ranging from less hazardous 

chemicals to more hazardous chemicals. 

Once the appropriate hazard group has 

been determined from the hazard 

statements (e.g., ‘‘Hazard Group B’’), 

exposure potential is evaluated based on 

the quantity in use, volatility (for 

liquids), or particulate nature (for 

solids). After evaluating these properties 

and categorizing the chemical into 

hazard and exposure bands, the 

chemicals are matched, based on their 

band categorization, to the appropriate 

control strategy, with more stringent 

controls applied for substances that are 

placed in high-toxicity bands. 

The Control of Substances Hazardous 

to Health (COSHH) guidance issued by 

the Safety Executive (HSE) of the United 

Kingdom is one model of control 

banding (Health and Safety Executive, 

2013; Ex. #129). Under the 2002 COSHH 

regulation, employers must conduct a 

risk assessment to decide how to 

prevent employees from being exposed 

to hazardous substances in the 

workplace. COSHH principles first 

require that exposure is prevented by 

employers, to the extent possible, by 

means of: 

• Changing the way tasks are carried 

out so that exposures aren’t necessary 

anymore; 

• Modifying processes to cut out 

hazardous by-products or wastes; or 

• Substituting a non-hazardous or 

less hazardous substance for a 

hazardous substance with new 

substances (or use the same substance in 

a different form) so that there is less risk 

to health. 

If exposures to hazardous substances 

cannot be prevented entirely, then 

COSHH requires employers to 

adequately control them (Control of 

Substances Hazardous to Health 

Regulations, 2002; Ex. #130). 

Recognizing that many small employers 

may not have access to the required 

expertise, and also to reduce the need 

for a professional and to promote 

consistency in the assessment process, 

the HSE developed an approach to 

assessment and control of chemical 

hazards using control banding 

methodologies spelled out in the 2002 

regulation. This control banding 

approach is described in detail in 

COSHH Essentials. Employers may use 

the guidance spelled out in the COSHH 

Essentials guide to determine the 

appropriate control approach for the 

chemical hazard in question. Each 

control approach covers a range of 

actions that work together to reduce 

exposure: (1) General Ventilation, (2) 

Engineering Controls, (3) Containment, 

and lastly, (4) Special—a scenario where 

employers should seek expert advice to 

select appropriate control measures. 

The first step outlined under the 

COSHH Essentials guidance is to 

consult the safety data sheet for each 

chemical in use. Employers must record 

the date of assessment, the name of the 

chemical being assessed, the supplier of 

the chemical, and the task(s) for which 

the chemical is used. 

Step two involves the determination 

of the health hazard. Employers 

ascertain the hazard by assessing the 

possible health effects from the hazard 

statements provided on the SDS, the 

amount in use, and the dustiness or 

volatility of the chemical in use. 

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Employers reference the hazard 

statements found on chemical safety 

data sheets against a table of COSHH 

hazard groups in order to categorize 

them into the appropriate hazard group 

(‘‘A’’ through ‘‘E’’, and possibly ‘‘S’’). 

Chemicals in Group A tend to be 

regarded as less harmful and may, for 

example, cause temporary irritation. 

Chemicals in Group E are the most 

hazardous and include known 

carcinogens. Group S encompasses 

substances that have special 

considerations for damage caused via 

contact with the eyes or skin. 

Additionally, Step two requires 

employers to make some determinations 

about the quantity and physical state of 

chemicals in use. They must decide if 

the amount of chemical in use would be 

described as ‘‘small’’ (grams or 

milliliters), ‘‘medium’’ (kilograms or 

liters), or ‘‘large’’ (tons or cubic meters). 

When in doubt, COSHH Essentials 

principles encourage employers to err 

on the side of the larger quantity in 

making their determination. 

Additionally, the physical state of 

chemicals effect how likely they are to 

get into the air and this affects the 

control approach to be utilized. For 

solids, COSHH Essentials guides 

employers to make a determination of 

either ‘‘Low’’, ‘‘Medium’’, or ‘‘High’’ 

dustiness based upon visible criteria 

observed during the use of these 

chemicals. Employers may also use 

look-up tables provided in the COSHH 

Essentials guide to make a 

determination of whether liquids have 

‘‘low’’, ‘‘medium’’, or ‘‘high’’ volatility 

based upon the chemical’s boiling point 

and ambient or process operating 

temperatures. 

In Step three of the COSHH Essentials 

guide, employers identify the 

appropriate control approach. Tables 

provided by the COSHH Essentials 

guide show the control approaches for 

hazard groups ‘‘A’’ through ‘‘E’’ 

according to quantity of chemical in use 

and its dustiness/volatility. Table-II 

illustrates how the control approaches 

are assigned. The control approaches 

referred to by number in the table are: 

1) General Ventilation, 2) Engineering 

Control, 3) Containment, and 4) Special. 

(Health and Safety Executive, 2009; Ex. 

#131). 


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Additionally, the COSHH Essentials 

guide provides detailed control 

guidance sheets for a range of common 

tasks. Consultation of these task-specific 

guidance sheets constitutes Step four 

under COSHH Essentials. Step five of 

COSHH Essentials involves the 

employer deciding on how best to 

implement control measures as 

prescribed. COSHH Essentials 

principles also stress the importance of 

employers reviewing their assessments 

regularly, especially if there is a 

significant change in workplace 

processes or environment. Employers 

are encouraged to incorporate exposure 

level monitoring, health surveillance, 

and relevant training. 

A number of European Union nations 

(e.g., United Kingdom, Germany, 

France, Netherlands, Norway, and 

Belgium) and Asian nations (Singapore 

and Korea) already utilize control 

banding methods comparable to COSHH 

Essential methods for management of a 

variety of chemical exposures in the 

workplace. 

A number of studies have been 

conducted to assess the validity of a 

control banding model for control of 

exposure to chemicals. Jones and Nicas 

(2006; Ex. #132) reviewed the COSHH 

Essentials model for hazard-banding in 

vapor degreasing and bag-filling tasks. 

Their study showed that the model did 

not identify adequate controls in all 

scenarios with approximately eighteen 

percent of cases leaving workers 

potentially under-protected. However, 

in a similar study, Hashimoto et al. 

(2007; Ex. #133) showed that hazardbanding tended to overestimate the level 

of control and therefore was more 

protective. In 2011, Lee et al. (Ex. #134) 

found that for a paint manufacturing 

facility using mixtures of chemicals 

with different volatilities, exposure to 

the chemicals with higher volatility had 

a higher likelihood to exceed the 

predicted hazard-band. Lee also 

recommended further research for more 

precise task identification to better 

enable implementation of task-specific 

control measures. 

NIOSH provides a thorough review 

and critical analysis of the concepts, 

protective nature, and potential barriers 

to implementation of control banding 

programs (NIOSH, 2009; Ex. #135). 

NIOSH concluded that control banding 

can be used effectively for performing 

workplace risk assessments and 

implementing control solutions for 

many, but not all occupational hazards. 

Additionally, NIOSH found that while 

in some situations in which control 

banding cannot provide the precision 

and accuracy necessary to protect 

worker health, and in some cases 

control banding will provide a higher 

level of control than is necessary. 

COSHH Essentials and other control 

banding concepts developed in Europe 

were based initially on the European 

Union’s pre-GHS classification and 

labeling system. Since the European 

Union has adopted the GHS in its 

classification and labeling rules, these 

risk phrases will no longer be available. 

Control banding approaches are now 

based on the hazard statements in the 

GHS. OSHA’s adoption of the GHS to 

modify the HCS opens up the 

opportunity to use a control banding 

approach to chemical exposures in 

American workplaces based on the 

hazard classification system. This 

would be an alternative to focusing on 

PELs that could achieve the goal of risk 

management for many chemicals and 

operations in workplaces. 

OSHA is interested in exploring how 

it might employ these non-OEL 

approaches in a regulatory framework to 

address hazardous substances where the 

available hazard information does not 

yet provide a sufficient basis for the 

Agency’s traditional approach of using 

risk assessment to establish a PEL. 

OSHA believes that a hazard banding 

approach could allow the Agency to 

establish specification requirements for 

the control of chemical exposures more 

efficiently, offering additional flexibility 

to employers, while maintaining the 

safety and health of the workforce. 

Although health hazard banding and 

control banding show some promise as 

vehicles for providing guidance to 

occupational health professionals for 

controlling exposures to workers, their 

use in a regulatory scheme presents 

challenges. For example, the agency 

would need to consider how, if it were 

to require such approaches, the OSH 

Act’s requirement that standards that 

reduce significant risk to the extent 

feasible might be satisfied. 

OSHA is also interested in exploring 

the development of voluntary guidelines 

for incorporation of control banding into 

safety and health management programs 

in U.S. workplaces. These efforts might 

include the development and 

dissemination of compliance assistance 

materials (publications, safety and 

health topic Web pages, computer 

software and smartphone apps, e-Tools) 

as well as consultation services to assist 

small businesses. 

Question V.B.8: How could OSHA use 

the information generated under 

HazCom 2012 to pursue means of 

managing and controlling chemical 

exposures in an approach other than 

substance-by-substance regulation? 

Question V.B.9: How could such an 

approach satisfy legal requirements to 

reduce significant risk of material 

impairment and for technological and 

economic feasibility? 

Question V.B.10.: Please describe 

your experience in using health hazard 

and/or control banding to address 

exposures to chemicals in the 

workplace. 

Question V.B.11.: Are additional 

studies available that have examined the 

effectiveness of health hazard and 

control banding strategies in protecting 

workers? 

Question V.B.12.: How can OSHA 

most effectively use the concepts of 

health hazard and control banding in 

developing health standards? 

V.B.13.: How might OSHA use 

voluntary guidance approaches to assist 

businesses (particularly small 

businesses) with implementing the 

principles of hazard banding in their 

chemical safety plans? Could the GHS 

chemical classifications be the starting 

point for a useful voluntary hazard 

banding scheme? What types of 

information, tools, or other resources 

could OSHA provide that would be 

most effective to assist businesses, 

unions, and other safety and health 

stakeholders with operationalizing 

hazard banding principles in the 

workplace? 

Question V.B.14.: Should OSHA 

consider greater use of specification 

standards or guidance as an approach to 

developing health standards? If so, for 

what kinds of operations are 

specification approaches best suited? 

6. Task-based Exposure Assessment and 

Control Approaches 

Job hazard analysis is a safety and 

health management tool in which 

certain jobs, tasks, processes or 

procedures are evaluated for potential 

hazards or risks, and controls are 

implemented to protect workers from 

injury and illness. Likewise, task-based 

assessment and control is a system that 

categorizes the task or job activity in 

terms of exposure potential and 

requirements for specific actions to 

control the exposure are implemented, 

regardless of occupational exposure 

limits. Tasks are isolated from the 

deconstruction of a larger process that is 

in turn part of an overall operation or 

project in an industrial setting. As 

industrial engineering explores the 

optimization of complex processes or 

systems through an evaluation of the 

integrated system of people, equipment, 

materials, and other components, the 

task-based system attempts to evaluate 

work activities to define uniform 

exposure scenarios and their variables 

and establish targeted control strategies. 

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Task-based exposure potential can be 

defined using readily available data 

including process operating procedures, 

task observation and analysis, job 

activity description, chemical inventory 

and toxicity information (hazard 

communication), historical exposure 

data, existing exposure databases, 

employee surveys, and current exposure 

data. Based on this exposure 

assessment, the task is matched with 

specific requirements for exposure 

control. Control specifications can draw 

on a broad inventory of exposure 

controls and administrative tools to 

reduce and prevent worker exposure to 

the identified hazardous substances. 

OSHA is interested in exploring taskbased control approaches as a technique 

for developing specification standards 

for the control of hazardous substances 

in the workplace as an alternative or 

supplement to PELs. Such an approach 

may offer the advantage of providing 

employers with specific guidance on 

how to protect workers from exposure 

and reduce or eliminate the need for 

conducting regular exposure 

assessments to evaluate the 

effectiveness of exposure control 

strategies. OSHA has developed 

specification-oriented health standards 

in the past, in particular, those for lead 

and asbestos in construction. 

More recently, OSHA developed a 

control-specification-based approach for 

controlling exposures to crystalline 

silica dust in construction operations 

(OSHA, 2009; Ex. #136, OSHA, 2013b; 

Ex. #137). Construction operations are 

particularly amenable to specification 

standards due to the task-based nature 

of the work. The National Institute for 

Occupational Safety and Health 

(NIOSH), the Center to Protect Workers’ 

Rights—a research arm of the Building 

and Construction Trades Department, 

AFL-CIO—has developed and used a 

‘‘Task-Based Exposure Assessment 

Model (T–BEAM)’’ for construction. The 

characteristic elements of T–BEAM are: 

(1) an emphasis on the identification, 

implementation, and evaluation of 

engineering and work practice controls; 

and (2) use of experienced, specially 

trained construction workers 

(construction safety and health 

specialists) in the exposure assessment 

process. A task-based approach was 

used because tasks, or specialized skills, 

form the single greatest thread of 

continuity in the dynamic environment 

of construction (Susi et al., 2000; Ex. 

#138). 

A new American National Standards 

Institute Standard (ANSI A10.49) based 

on GHS health hazard categories and 

utilizing a task-based approach is also 

being developed to address chemical 

hazards in construction (ASSE, 2012; 

Ex. #139). The standard requires 

employers to first identify tasks 

involving the use of chemicals and 

create a hazard communication 

inventory for these tasks. Then the 

employer must determine the hazard 

level and exposure level, and finally 

develop a control plan based on the 

hazard and exposure classifications. If 

the chemicals used in the task are low 

hazard and the task is low exposure, 

then the control plan requires following 

the SDS and label precautions. If, 

however, the task involves greater than 

minimal hazard or exposure, a more 

protective control plan must be 

developed. 

However, developing specification 

standards governing exposure to health 

standards for general industry 

operations presents a different 

challenge. Given the diversity in the 

nature of industrial operations across a 

range of industry sectors that might be 

affected by a chemical standard, OSHA 

is concerned that it will be more 

difficult to develop specification 

standards for exposure controls that are 

specific enough to clearly delineate 

obligations of employers to protect 

employees, and yet are general enough 

to provide employers flexibility to 

implement controls that are suitable for 

their workplaces and that allow for 

future innovation in control 

technologies. 

Question V.B.15: OSHA requests 

comment on whether and how taskbased exposure control approaches 

might be effectively used as a regulatory 

strategy for health standards. 

VI. Authority and Signature 

David Michaels, Ph.D., MPH, 

Assistant Secretary of Labor for 

Occupational Safety and Health, U.S. 

Department of Labor, 200 Constitution 

Avenue NW., Washington, DC 20210, 

directed the preparation of this notice. 

OSHA is issuing this notice under 29 

U.S.C. 653, 655, 657; 33 U.S.C. 941; 40 

U.S.C. 3704 et seq.; Secretary of Labor’s 

Order 1–2012 (77 FR 3912, 1/25/2012); 

and 29 CFR Part 1911. 

Signed at Washington, DC, on September 

30, 2014. 

David Michaels, 

Assistant Secretary of Labor for Occupational 

Safety and Health. 

Appendix A: History, Legal 

Background, and Significant Court 

Decisions 

I. Background 

Since the OSH Act was enacted in 1970, 

OSHA has made significant achievements 

toward improving the health and safety of 

America’s workers. The OSH Act gave ‘‘every 

working man and woman in the Nation’’ for 

the first time, a legal right to ‘‘safe and 

healthful working conditions.’’ OSH Act 

§ 2(a); 29 U.S.C. 651. (Ex. #9) Congress 

recognized that ‘‘the problem of assuring safe 

and healthful workplaces for our men and 

women ranks in importance with any that 

engages the national attention today.’’ S. Rep. 

91–1282 at 2 (1970; Ex. #17). Indeed, when 

establishing the OSH Act, Congress was 

concerned about protecting workers from 

known hazards as well as from the numerous 

new hazards entering the workplace: 

Occupational diseases which first 

commanded attention at the beginning of the 

industrial revolution are still undermining 

the health of workers. . . . Workers in dusty 

trades still contract various respiratory 

diseases. Other materials long in industrial 

use are only now being discovered to have 

toxic effects. In addition, technological 

advances and new processes in American 

industry have brought numerous new 

hazards to the workplace. S. Rep. 91–1282 at 

2. 

Many of the occupational diseases first 

discovered during the industrial revolution, 

and which later spurred Congress to create 

OSHA, still pose a significant harm to U.S. 

workers. While the number of hazardous 

chemicals to which workers are exposed has 

increased exponentially due to new 

formulations of chemical mixtures, OSHA 

has not been successful in establishing 

standards that adequately protect workers 

from hazardous chemical exposures, even 

from the older, more familiar chemicals. 

OSHA’s PELs are mandatory limits for air 

contaminants above which workers must not 

be exposed. OSHA PELs generally refer to 

differing amounts of time during which the 

worker can be exposed: (1) Time weighted 

averages (TWAs) which establish average 

limits for eight-hour exposures; (2) short-term 

limits (STELs) which establish limits for 

short term exposures; and (3) ceiling limits, 

which set never-to-be exceeded maximum 

exposure levels. 

OSHA’s PELs have existed nearly as long 

as the agency itself. Most of OSHA’s current 

PELs were adopted by the agency in 1971. 

OSHA currently has PELs for approximately 

470 hazardous substances, which are 

included in the Z-Tables in general industry 

at 29 CFR part 1910.1000 (Ex. #4) and in 

three maritime subsectors: Part 1915.1000 

(Shipyard Employment; Ex. #5); part 1917 

(Marine Terminals; Ex. #140); and part 1918 

(Longshoring; Ex. #141). Z-Tables that apply 

in construction are found at part 1926.55 (Ex. 

#6). There are inconsistencies in the PELs 

that apply across industry sectors which 

resulted from the regulatory history of each 

divergent industry sector. 

As discussed in further detail below, the 

Agency attempted to update the general 

industry PELs in 1989, but that revision was 

vacated by judicial decision in 1992. As 

such, the 1971 PELs remain the exposure 

limits with which most U.S. workplaces are 

required to comply. The Agency also 

promulgates ‘‘comprehensive’’ substancespecific standards (e.g., lead, methylene 

chloride) which, in addition to PELs, require 

additional ancillary provisions such as 

housekeeping, exposure monitoring, and 

medical surveillance. 

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II. OSHA’s Statutory Authority, Adoption of 

the PELs in 1971, and the 1989 Attempted 

Revision 

A. The Purpose of the OSH Act and OSHA’s 

Authority To Regulate Hazardous Chemicals 

The OSH Act vests the Secretary of Labor 

with the power to ‘‘promulgate, modify, or 

revoke’’ mandatory occupational safety and 

health standards. OSH Act section 6(b), 29 

U.S.C. 655(b). An ‘‘occupational safety and 

health standard,’’ as defined by section 3(8) 

of the OSH Act, is a ‘‘standard which 

requires conditions, or the adoption or use of 

one or more practices, means, methods, 

operations, or processes, reasonably 

necessary or appropriate to provide safe or 

healthful employment and places of 

employment.’’ OSH Act section 3(8), 29 

U.S.C. 652(8). (Ex. #9) 

The OSH Act provides three separate 

approaches for promulgating standards. The 

first approach, in section 6(a) of the OSH Act, 

provided OSHA with an initial two-year 

window in which to adopt standards without 

hearing or public comment. Additionally, 

sections 6(b) and 6(c) provide methods 

currently available to the agency for 

promulgating health standards. Section 6(b) 

allows OSHA to create and update standards 

through notice and comment rulemaking, 

and section 6(c) provides OSHA with the 

authority to set emergency temporary 

standards. OSHA has not successfully 

adopted an emergency temporary standard 

for over thirty years, and it is not discussed 

further here. 

B. The Adoption of the PELs Under Section 

6(a) 

Under section 6(a), OSHA was permitted to 

adopt ‘‘any national consensus standard and 

any established Federal standard’’ so long as 

the standard ‘‘improved safety or health for 

specifically designated employees.’’ 29 

U.S.C. 655(a). The purpose of providing 

OSHA with this two-year window ‘‘was to 

establish as rapidly as possible national 

occupational safety and health standards 

with which industry is familiar.’’ S. Rep. 91– 

1282 at 6. When establishing this fast track 

to rulemaking, Congress emphasized the 

temporary nature of the approach, noting that 

these ‘‘standards may not be as effective or 

up to date as is desirable, but they will be 

useful for immediately providing a 

nationwide minimum level of health and 

safety.’’ S. Rep. 91–1282 at 6. (Ex. #17) 

Establishing PELs was one of the first 

actions taken by OSHA. Most of the PELs 

contained in the Tables Z–1, Z–2, and Z–3 

of 29 CFR 1910.1000 (Ex. #4) for general 

industry, as well as those in construction and 

maritime were adopted during the initial 

two-year window under section 6(a). OSHA 

adopted approximately 400 occupational 

exposure limits for general industry that were 

based on the American Conference of 

Governmental Industrial Hygienist’s (ACGIH) 

1968 list of Threshold Value Limits (TLVs). 

In addition, about 25 additional exposure 

limits recommended by the American 

Standards Association (presently called the 

American National Standards Institute) 

(ANSI), were adopted as national consensus 

standards. 36 FR 10466 (Ex. #142). Currently 

the exposure limits that apply to construction 

were derived from the 1970 ACGIH TLVs and 

certain substance specific Sec. 6(b) standards. 

The industry sector that is referred to today 

as ‘‘Maritime’’ has a long and somewhat 

confusing history. The Department of Labor 

has had some authority since 1958 for the 

maritime industry under the Longshore and 

Harbor Workers Compensation Act (33 U.S.C. 

901 et seq.). Specifically authority was 

granted under Public Law 89–742 for the 

Secretary of Labor to issue regulations to 

protect the health and safety of 

longshoremen, marine terminal workers, ship 

repairers, shipbuilders, and ship breakers. 

Under Section 4(b)(2) of the OSH Act, 33 

U.S.C. 941 (Ex. #143) became OSHA 

standards in 1971. 

At that time, the Shipyard standards were 

in three parts of 29 CFR; part 1915 for ship 

repairing, part 1916 for shipbuilding and part 

1917 for shipbreaking. In 1982 parts 1915, 

1916 and 1917 were consolidated into a new 

part 1915, Shipyards. As a consequence of 

their history, the PELs applicable to the new 

part 1915, Shipyards, are complex. 

Depending upon the specific operation, 

either the 1970 TLVs or 1971 PELS 

(originally 1968 TLVs) apply. See §§ 1915.11, 

1915.12, 1915.32 and 1915.33 (Ex. #144). 

Additionally, several of the OSHA singlesubstance standards apply. 

Pursuant to the Longshoremen and Harbor 

Worker Compensation Acts of 1958 

amendments, in 1960 OSHA issued 

regulations protecting longshore employees, 

along with marine terminal employees. These 

regulations were adopted as OSHA standards 

and later recodified. In 1983, OSHA issued 

a final standard specifically covering marine 

terminals (29 CFR part 1917) separately from 

longshoring. The Marine Terminal Standard 

basically requires that no employee be 

exposed to air contaminants over the limits 

set in the 1971 Z-Tables. See §§ 1917.2, 

1917.22, 23, 25. (Ex. #140) 

Longshoring operations continue to be 

regulated by 29 CFR Part 1918 (Ex. #141). 

OSHA has consistently interpreted that the 

air contaminant exposure limits set forth in 

1910.1000 (Ex. #4) are applicable pursuant to 

1910.5(c) to longshoring because no 

quantitative exposure limits are set forth for 

air contaminants, other than carbon 

monoxide. 

As discussed above, the Agency was given 

authority to adopt standards to provide 

initial protections for workers from what the 

Congress deemed to be the most dangerous 

workplace threats. Congress felt that it was 

‘‘essential that such standards be constantly 

improved and replaced as new knowledge 

and techniques are developed.’’ S. Rep. 91– 

1282 at 6. (Ex. #17) However, because OSHA 

has been unable to update the PELs, they 

remain frozen at the levels at which they 

were initially adopted. OSHA’s PELs are 

largely based on acute health effects and do 

not take into consideration newer research 

regarding chronic effects occurring at lower 

occupational exposures. Thus, although there 

have been radical changes in our 

understanding of airborne contaminants, 

updates in technology, and changes to 

industry practices, OSHA’s PELs are still 

based on research performed during the 

1950s and 1960s. In contrast, the ACGIH 

annually reviews chemical substances and 

updates its list of TLVs®. Where OSHA 

currently has PELs for approximately 470 

chemical hazards, the ACGIH recommends 

TLVs® for more than 700 chemical 

substances and physical agents, 

approximately 200 of which have been 

updated since 1971. (FACOSH, 2012; Ex. 

#145). 

C. Section 6(b) Notice and Comment 

Rulemaking 

Section 6(b) of the OSH Act provides 

OSHA with the authority to promulgate 

health standards. OSHA promulgates two 

main types of health standards: (i) PELs, and 

(ii) comprehensive standards, which, as the 

name implies, consist of provisions to protect 

workers in addition to PELs. Section 6(b)(5) 

imposes specific requirements governing the 

adoption of health standards: 

[T]he Secretary, in promulgating standards 

dealing with toxic materials or harmful 

physical agents under this subsection, shall 

set the standard which most adequately 

assures, to the extent feasible, on the basis of 

the best available evidence, that no employee 

will suffer material impairment of health or 

functional capacity even if such employee 

has regular exposure to the hazard dealt with 

by such standard for the period of his 

working life. Development of standards 

under this subsection shall be based upon 

research, demonstrations, experiments, and 

such other information as may be 

appropriate. In addition to the attainment of 

the highest degree of health and safety 

protection for the employee, other 

considerations shall be the latest available 

scientific data in the field, the feasibility of 

the standards, and experience gained under 

this and other health and safety laws. 

Whenever practicable, the standard 

promulgated shall be expressed in terms of 

objective criteria and of the performance 

desired. 

29 U.S.C. 655(6)(b)(5). (Ex. #9) 

The courts have elaborated on the findings 

OSHA must make before adopting a 6(b)(5) 

standard. One such case, Industrial Union 

Dept., AFL–CIO v. American Petroleum 

Institute, 448 U.S. 607 (1980) (the Benzene 

case; Ex. #10), has had a major impact on 

OSHA rulemaking by establishing a 

threshold requirement that before the agency 

can promulgate a health standard it must 

show that a significant risk of material 

impairment exists, which can be eliminated 

or lessened by a change in practices. 

Additionally, the phrase ‘‘to the extent 

feasible’’ in section 6(b)(5) has been 

interpreted by the courts to require that 

OSHA show that a standard is both 

economically and technologically feasible. 

American Textile v. Donovan, 452 U.S. 490 

(1981) (the Cotton Dust case; Ex. #15); United 

Steelworkers v. Marshall, 647 F.2d 1189, 

1264 (D.C. Cir. 1980) (the Lead I case; Ex. 

#12). These cases will be discussed in greater 

detail in Section III of this Appendix. 

D. 1989 Air Contaminants Standard 

In 1989, OSHA published the Air 

Contaminants final rule, which remains the 

Agency’s most significant attempt at 

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updating the PELs. Unlike typical substancespecific rulemakings, where OSHA develops 

a comprehensive standard, the Air 

Contaminants final rule was only intended to 

update existing PELs and to add new PELs 

for substances not currently regulated. As 

such, the final rule did not include ancillary 

provisions (e.g. exposure monitoring, 

medical surveillance, requirements for 

personal protective equipment, or labeling) 

because OSHA determined that these 

provisions would delay and unnecessarily 

complicate the PELs update. Appendix B. to 

this Request for Information contains the 

table of PELs from the 1989 Air 

Contaminants Final Rule. The table includes 

both PELs originally adopted by OSHA in 

1971 and the PELs established under the 

1989 final rule. 

In order to determine a starting point for 

updating the general industry PELs for 

chemicals on Tables Z–1, Z–2, and Z–3 of 29 

CFR 1910.1000 (Ex. #4), and for creating new 

PELs for some substances not listed in those 

tables, OSHA analyzed existing databases 

and lists of occupational exposure limits 

(OELs) to determine the scope of the 

rulemaking. After extensive review of all 

available sources of OELs, including the 

National Institute for Occupational Safety 

and Health (NIOSH) Recommended Exposure 

Levels (RELs), the American Conference of 

Industrial Hygienists (ACGIH) Threshold 

Limit Values (TLVs®), the American 

Industrial Hygiene Association (AIHA) 

Workplace Environmental Exposure Levels 

(WEELs), and limits from other countries, 

OSHA ultimately selected the ACGIH’s 1987– 

88 TLVs to identify the basis for which 

substances and corresponding exposure 

values that would be included in the 

proposed rule. 53 FR 20977. The TLVs were 

selected as a reference point because of the 

number of substances they covered, the 

availability of written documentation on how 

the TLVs were selected, and the general 

acceptance of the TLVs by industrial 

hygienists, other occupational health 

professionals, and industry. (53 FR 20967; 

Ex. #18, 54 FR 2375; Ex. #7) 

After determining the scope of hazardous 

chemicals to be included in the rulemaking, 

OSHA began the process of identifying the 

most appropriate new PELs to be proposed. 

OSHA considered both the ACGIH TLVs and 

the NIOSH RELs as a starting point. (53 FR 

20966–67; Ex. #18) When the TLV and REL 

were similar, OSHA reviewed both the 

ACGIH documentation and the NIOSH 

recommendation. Where the TLV and REL 

‘‘differed significantly,’’ OSHA reviewed the 

studies and reasoning upon which the 

NIOSH and ACGIH recommendations were 

based to determine which was more 

appropriate. OSHA presumed that a 

significant difference did not exist between 

the TLV and the REL for a chemical when: 

(a) The TLV and REL values are the same; 

(b) TLV and REL values differ by less than 

10 percent; 

(c) The TLV and REL Time Weighted 

Averages (TWA) are the same, but there are 

differences in the Short Term Exposure Limit 

(STEL) or Ceiling (C); or 

(d) The TWA in one data base is the same, 

or one-half, the STEL/C in the other data 

base. 53 FR 20977. 

In reviewing the evidence, OSHA first 

determined whether the studies and analyses 

were valid and of reasonable scientific 

quality. Second, it determined, based on the 

studies, if the published documentation of 

the REL or TLV would meet OSHA’s legal 

requirements for setting a PEL. Thus, OSHA 

reviewed the evidence of significant risk at 

the existing PEL or, if there was no PEL, at 

exposures which might exist in the 

workplace in the absence of any limit. Third, 

OSHA reviewed the studies to determine if 

the new PEL would lead to substantial 

reduction in significant risk. 54 FR 2372. 

OSHA’s determination of where the new 

PEL should be set was based on its review 

and analysis of the information found in 

these sources. OSHA set the new PELs based 

on a review of the available evidence. 54 FR 

2402. Safety factors were applied on a caseby-case basis. (54 FR 2365, 2399; Ex. #7). 

Based on the analysis discussed above, 

OSHA summarized the health evidence for 

each individual substance and determined 

when and at what level a new limit was 

necessary to substantially reduce a 

significant risk of material impairment of 

health or functional capacity among 

American workers. The following example 

illustrates the type of analysis that OSHA 

conducted for each substance: 

OSHA had no former limit for potassium 

hydroxide. A ceiling limit of 2 mg/m(3) was 

proposed by the Agency based on the ACGIH 

recommendation, and NIOSH (Ex. 8–47, 

Table N1) concurred with this proposal. 

OSHA has concluded that this limit is 

necessary to afford workers protection from 

irritant effects and is establishing the 2-mg/ 

m(3) ceiling limit for potassium hydroxide in 

the final rule. 

[One commenter] (Ex. 3–830) commented 

that there was no basis for establishing an 

occupational limit for potassium hydroxide. 

OSHA disagrees and notes that the irritant 

effects of potassium hydroxide dusts, mists, 

and aerosols have been documented (ACGIH 

1986/Ex. 1–3, p. 495; Karpov 1971/Ex. 1– 

1115). Although dose-response data are 

lacking for this substance, it is reasonable to 

expect potassium hydroxide to exhibit 

irritant properties similar to those of sodium 

hydroxide, a structurally related strong 

alkali. In its criteria document, NIOSH 

(1976k/Ex. 1–965) cites a personal 

communication (Lewis 1974), which reported 

that short-term exposures (2 to 15 minutes) 

to 2 mg/m(3) sodium hydroxide caused 

‘‘noticeable’’ but not excessive upper 

respiratory tract irritation. Therefore, OSHA 

finds that the 2-mg/m(3) ceiling limit will 

provide workers with an environment that 

minimizes respiratory tract irritation, which 

the Agency considers to be material 

impairment of health. To reduce these risks, 

OSHA is establishing a ceiling limit of 2 mg/ 

m(3) for potassium hydroxide. (54 FR 2332 

et seq.) 

OSHA proposed making 212 PELs more 

protective and setting new PELs for 164 

substances not previously regulated by 

OSHA. Substances for which the PEL was 

already aligned with a newer TLV were not 

included. 

In order to determine whether the Air 

Contaminants rule was feasible, OSHA 

prepared the regulatory impact analysis in 

two phases. The first phase of its feasibility 

analyses involved using secondary databases 

to collect information on the chemicals to be 

regulated and the industries in which they 

were used. These databases provided 

information on the toxicity and health effects 

of exposure to chemicals covered by the 

rulemaking, on engineering controls, and on 

emergency response procedures. (54 FR 2725; 

Ex. #7). 

Two primary databases were used to 

collect information on the nature and extent 

of employee exposures to the substances 

covered by the rule. One database was the 

1982 NIOSH National Occupational Exposure 

Survey (NOES), which collected information 

from 4,500 businesses on the number of 

workers exposed to hazardous substances. 

The second database was OSHA’s Integrated 

Management Information System (IMIS) 

which contains air samples taken since 1979 

by OSHA industrial hygienists during 

compliance inspections. OSHA also 

consulted industrial hygienists and engineers 

who provided information about the 

exposure controls in use, the number and 

size of plants that would be impacted by the 

rulemaking, and the estimated costs 

associated with meeting the new PELs. (54 

FR 2373, 2725, 2736; Ex. #7). 

As part of the second phase of its 

feasibility analyses, OSHA performed an 

industry survey and site visits. The survey 

was the largest survey ever conducted by 

OSHA and included responses from 5,700 

firms in industries believed to use chemicals 

included in the scope of the Air 

Contaminants proposal. It was designed to 

focus on industry sectors that potentially had 

the highest compliance costs, identified 

through an analysis of existing exposure data 

at the four-digit SIC (Standards Industrial 

Classification) code level. 54 FR 2843. The 

survey gathered data on chemicals, 

processes, exposures and controls currently 

in use, which ‘‘permitted OSHA to refine the 

Phase I preliminary estimates of technical 

and economic feasibility. Site visits to 90 

firms were conducted to verify the data 

collected on chemicals, processes, controls, 

and employee exposures.’’ 54 FR 2725; see 

also 54 FR 2736–39, 2768, 2843–69. 

OSHA analyzed the data collected in 

phases I and II to determine whether the 

updated PELs were both technologically and 

economically feasible for each industry 

sector covered. 54 FR 2374. 

For technological feasibility, OSHA 

evaluated engineering controls and work 

practices available within industry sectors to 

reduce employee exposures to the new PELs. 

In general, it found three types of controls 

might be employed to reduce exposures: 

Engineering controls, work practice and 

administrative controls, and personal 

protective equipment. Engineering controls 

included local exhaust ventilation, general 

ventilation, isolation of the worker and 

enclosure of the source of the emission, and 

product substitution. Work practice controls 

included housekeeping, material handling 

procedures, leak detection, training, and 

personal hygiene. Personal protective 

equipment included respirators, and where 

the chemicals involved presented skin 

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hazards, protective gloves and clothing. 54 

FR 2789–90, 2840. 

OSHA found that many processes required 

to reduce exposure were ‘‘relatively 

standardized throughout industry and are 

used [to control exposures] for a variety of 

substances.’’ 54 FR 2373–74. It ‘‘examined 

typical work processes found in a cross 

section of industries’’ and had industry 

experts identify the major processes that had 

the potential for hazardous exposures above 

the new PELs, requiring new controls. For 

each affected industry group, OSHA 

reviewed the data it had collected to 

‘‘identify examples of successful application 

of controls to these processes.’’ 54 FR 2790. 

Based on its review OSHA found that 

‘‘engineering controls and improved work 

practices [were] available to reduce exposure 

levels in almost all circumstances.’’ 54 FR 

2727. In some cases, it found respirators or 

other protective equipment was necessary. 54 

FR 2727, 2813–15, 2840. For each relevant 

industry sector (which was at the 2, 3, or 4 

digit SIC code level, depending on the 

processes involved). As the court explained 

in Air Contaminants, 965 F.2d at 981 (Ex. 

#8): 

The SIC codes classify by type of activity 

for purposes of promoting uniformity and 

comparability in the presentation of data. As 

the codes go from two and three digits to four 

digits, the groupings become progressively 

more specific. For example, SIC Code 28 

represents ‘‘Chemicals and Allied Products,’’ 

SIC Code 281 represents ‘‘Industrial 

Inorganic Chemicals,’’ and SIC Code 2812 

includes only ‘‘Alkalies and Chlorine.’’ 

OSHA prepared a list of the processes 

identified and the engineering controls and 

personal protective equipment (PPE) required 

to reach the new PELs. 54 FR 2814–39. In 

almost all cases, the OSHA list showed that 

the new PELs could be reached through a 

combination of ventilation and enclosure 

controls. 54 FR 2816–39. OSHA received and 

addressed numerous comments on the 

controls it proposed for use in various 

industries. 54 FR 2790–2813. OSHA found 

that ‘‘in the overwhelming majority of 

situations where air contaminants [were] 

encountered by workers, compliance [could] 

be achieved by applying known engineering 

control methods, and work practice 

improvements.’’ 54 FR 2789. 

To assess economic feasibility, OSHA 

‘‘made estimates of the costs to reduce 

exposure based on the scale of operations, 

type of process, and degree of exposure 

reduction needed’’ based primarily on the 

results of the survey. 54 FR 2373, 2841–51. 

For each survey respondent, OSHA identified 

the processes employed at the plant and 

made a determination about whether workers 

would be exposed to a chemical in excess of 

a new PEL. 54 FR 2843–47. For those 

processes where the new PEL would be 

exceeded, OSHA estimated the cost of 

controls necessary to meet the PEL. 54 FR 

2947–51. Process control costs were then 

summed by establishment and costs ‘‘for the 

survey establishment were then weighted (by 

SIC and size) to represent compliance costs 

for the universe of affected plants.’’ 54 FR 

2851. OSHA received and addressed many 

comments on its cost approach and 

assumptions. (54 FR 2854–62; Ex. #7). 

Based on the survey, OSHA determined 

that 74 percent of establishments with 

hazardous chemicals had no exposures in 

excess of the new PELs and would incur no 

costs, 22 percent would incur costs to 

implement additional engineering controls, 

and 4 percent would be required to provide 

personal protective equipment only for 

maintenance workers. 54 FR 2851. OSHA 

estimated the total compliance cost to be 

$788 million per year annualized over ten 

years at a ten percent discount rate. 54 FR 

2851. OSHA assessed the economic impact of 

the standard on industry profits on the twodigit SIC level. Assuming industry would not 

be able to pass the additional costs on to 

customers, the average change in profits was 

less than one percent, with the largest change 

in SIC 30 (Rubber and Plastics) of 2.3 

percent. 54 FR 2885, 2887. Alternatively, 

assuming that industry could pass on all 

costs associated with the rule to its 

customers, OSHA determined that for no 

industry sector would prices increase on 

average more than half of a percent. 54 FR 

2886, 2887. In neither case was the economic 

impact significant, OSHA found, and the new 

standard was therefore considered by the 

Agency to be economically feasible. (54 FR 

2733, 2887; Ex. #7) 

The Air Contaminants final rule was 

published on January 19, 1989. In the final 

rule, OSHA summarized the health evidence 

for each individual substance, discussed over 

2,000 studies, reviewed and addressed all 

major comments submitted to the record, and 

provided a rationale for each new PEL 

chosen. The final rule differed from the 

proposal in a number of ways as OSHA 

changed many of its preliminary assessments 

presented in the proposal based on 

comments submitted to the record. 

Ultimately, the final rule adopted more 

protective PELs for 212 previously regulated 

substances, set new PELs for 164 previously 

unregulated substances, and left unchanged 

an additional 52 substances, for which lower 

PELs were initially proposed. OSHA 

estimated over 21 million employees were 

potentially exposed to hazardous substances 

in the workplace and over 4.5 million 

employees were currently exposed to levels 

above the old PELs or in the absence of a 

PEL. OSHA projected the final rule would 

result in potential reduction of over 55,000 

lost workdays due to illnesses per year and 

annual compliance with this final rule would 

prevent an average of 683 fatalities annually 

from exposures to hazardous substances. 54 

FR 2725. 

The update to the Air Contaminants 

standard generally received wide support 

from both industry and labor. However, there 

was dissatisfaction on the part of some 

industry representatives and union leaders, 

who brought petitions for review challenging 

the standard. For example, some industry 

petitioners argued that OSHA’s use of generic 

findings, the inclusion of so many substances 

in one rulemaking, and the allegedly 

insufficient time provided for comment by 

interested parties created a record inadequate 

to support the new set of PELs. In contrast, 

the unions challenged the generic approach 

used by OSHA to promulgate the standard 

and argued that several PELs were not 

protective enough. The unions also asserted 

that OSHA’s failure to include any ancillary 

provisions, such as exposure monitoring and 

medical surveillance, prevented employers 

from ensuring the exposure limits were not 

exceeded and resulted in less-protective 

PELs. 

Fifteen of the twenty-five lawsuits were 

settled; of the remaining suits, nine were 

from industry groups challenging seven 

specific exposure limits, and one was from 

the unions challenging 16 substances. 

Pursuant to 28 U.S.C. 2112(a), all petitions 

for review were consolidated for disposition 

and transferred to the Eleventh Circuit Court 

of Appeals. AFL–CIO v. OSHA, 965, F.2d 

962, 981–82 (11th Cir. 1992) (Air 

Contaminants). Although only 23 of the new 

PELs were challenged, the court ultimately 

decided to vacate the entire rulemaking, 

finding that ‘‘OSHA [had] not sufficiently 

explained or supported its threshold 

determination that exposure to these 

substances at previous levels posed a 

significant risk of these material health 

impairments or that the new standard 

eliminates or reduces that risk to the extent 

feasible.’’ Air Contaminants, 965 F.2d at 986– 

987; Ex. #8. 

After publishing the Air Contaminants 

Final Rule for general industry, OSHA 

proposed amending the PELs for the 

maritime and construction industry sectors 

and establishing PELs to cover the agriculture 

industry sector. OSHA published a Notice of 

Proposed Rulemaking (NPRM) on June 12, 

1992, which included more protective 

exposure limits for approximately 210 

substances currently regulated in the 

construction and maritime industries and 

added new exposure limits for approximately 

160 chemicals to protect these workers. (57 

FR 26002; Ex. #146). The notice also 

proposed approximately 220 PELs to cover 

the agriculture industry. OSHA extended the 

comment period indefinitely while it 

considered possible responses to the Air 

Contaminants court decision. Once it became 

clear that an appeal would not be pursued, 

the Agency halted work on the project. 

III. Significant Court Decisions Shaping 

OSHA’s Rulemaking Process and OSHA’s 

Approach to Updating Its Permissible 

Exposure Limits 

OSHA’s Air Contaminants final rule is the 

agency’s most significant attempt to move 

away from developing individual, substancespecific standards. As discussed above in 

Section II, this rule attempted to establish or 

revise 376 exposure limits for chemicals in 

a single rulemaking. OSHA’s efforts in 

reducing occupational illnesses and the 

mortality associated with hazardous 

chemical exposure has largely been through 

developing substance specific standards, 

such as Hexavalent Chromium general 

industry (29 CFR 1910.1026; Ex. #26), 

shipyards (29 CFR 1915.1026), and 

construction (29 CFR 1926.1026) and 

Methylene Chloride (29 CFR 1910.1052; Ex. 

#27). These standards, in addition to setting 

PELs, establish other provisions to help 

reduce risk to workers, such as requirements 

to monitor exposure, train workers and 

conduct medical surveillance, if appropriate. 

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However, due to the associated time and 

costs, promulgating comprehensive rules for 

individual chemical hazards is an ineffective 

approach to address all chemical hazard 

exposures because of the sheer number of 

chemicals and mixtures to which workers are 

exposed on a daily basis. To date, only 30 

comprehensive individual standards have 

been successfully published by the Agency to 

address hazardous chemicals in the 

workplace. 

The courts have had a significant impact 

on OSHA’s rulemaking process by 

articulating specific burdens OSHA must 

meet before promulgating a standard. It was 

because the Air Contaminants court found 

that OSHA had failed to meet some of these 

burdens that the court vacated OSHA’s 

attempt to update the PELs. This section 

discusses the important cases laying out 

OSHA’s burdens under the OSH Act, and 

summarizes the reasons the Air 

Contaminants court gave for finding that 

OSHA had not satisfied those burdens. These 

cases influence what steps OSHA may take 

in the future to update the PELs. 

A. The Substantial Evidence Test: OSHA’s 

Burden of Proof for Promulgating Health 

Standards 

The test used by the courts to determine 

whether OSHA has reached its burden of 

proof is the ‘‘substantial evidence test.’’ This 

test, which applies to policy decisions as 

well as factual determinations, is set forth in 

section 6(f) of the OSH Act, which states: 

‘‘the determinations of the Secretary shall be 

conclusive if supported by substantial 

evidence in the record considered as a 

whole.’’ 29 U.S.C. 655(f). ‘‘Substantial 

evidence’’ has been defined as ‘‘such relevant 

evidence as a reasonable mind might accept 

as adequate to support a conclusion.’’ Cotton 

Dust, 452 U.S. at 522; Ex. #15 (quoting 

Universal Camera Corp. v. NLRB, 340 U.S. 

474, 477 (1951) Ex. #16). 

Although the substantial evidence test 

requires OSHA to show that the record as a 

whole supports the final rule, OSHA is not 

required to wait for ‘‘scientific certainty’’ 

before promulgating a health standard. 

Benzene, 448 U.S. at 656 (Ex. #10). Rather, 

to meet its burden of proof under the 

‘‘substantial evidence test,’’ the agency need 

only ‘‘identify relevant factual evidence, to 

explain the logic and the policies underlying 

any legislative choice, to state candidly any 

assumptions on which it relies, and to 

present its reasons for rejecting significant 

contrary evidence and argument.’’ Lead I, 647 

F.2d. at 1207; Ex. #12. 

B. The Air Contaminants Case 

OSHA published the Air Contaminants 

final rule on January 19, 1989. As discussed 

in Section II, the standard adopted more 

protective PELs for 212 previously regulated 

substances, set new PELs for 164 previously 

unregulated substances, left unchanged the 

PELs for 52 substances for which lower limits 

had been proposed, and raised the PEL for 

one substance. 54 FR 2332. The rule was 

challenged by both industry and labor 

groups, which both raised a series of issues 

regarding the validity of the final rule. 

The first issue addressed by the court was 

whether OSHA’s ‘‘generic’’ approach to 

rulemaking used to update or create new 

PELs for 376 chemicals in a single 

rulemaking was permissible under the OSH 

Act. Although the Eleventh Circuit 

determined that the Air Contaminants final 

rule did not fit within the classic definition 

of a generic rulemaking, the court upheld the 

format used by OSHA to update the PELs. Air 

Contaminants, 965 F.2d at 972. The court, in 

so holding, reasoned ‘‘nothing in the OSH 

Act prevented OSHA from addressing 

multiple substances in a single rulemaking.’’ 

Air Contaminants, 965 F.2d at 972. The court 

also upheld OSHA’s statutory authority to 

select the substances and determine the 

parameters of its rules. However, the court 

stated that even though OSHA was permitted 

to promulgate multi-substance rules, each 

substance was required to ‘‘stand 

independently, i.e., . . . each PEL must be 

supported by substantial evidence in the 

record considered as a whole and 

accompanied by adequate explanation.’’ Air 

Contaminants, 965 F.2d at 972; Ex. #8. 

C. Significant Risk of a Material Impairment 

1. The Benzene Case and Significant Risk 

The significant risk requirement was first 

articulated in 1980 in a plurality decision of 

the Supreme Court in Benzene, 448 U.S. 607. 

The petitioners in Benzene challenged 

OSHA’s rule lowering its PEL for benzene 

from 10 ppm to 1 ppm. In support of the new 

PEL, OSHA found that benzene caused 

leukemia and that the evidence did not show 

that there was a safe threshold exposure level 

below which no excess leukemia would 

occur. Applying its policy to treat 

carcinogens as posing a risk at any level of 

exposure where such a threshold could not 

be established, OSHA chose the new PEL of 

1 ppm based on its finding that it was the 

lowest feasible exposure level. This was 

because Section 6(b)(5) of the OSH Act 

requires standards to be set at the most 

protective level that is feasible. See Benzene, 

448 U.S. at 633–37; Ex. #10. 

The Benzene Court rejected OSHA’s 

approach. First, it found that the OSH Act 

did not require employers to ‘‘eliminate all 

risks of harm from their workplaces.’’ The 

OSH Act defines ‘‘occupational safety and 

health standard’’ to be standard that require 

the adoption of practices which are 

‘‘reasonably necessary or appropriate to 

provide safe or healthful employment and 

places of employment’’. OSH Act § 3(8), 29 

U.S.C. 652(8); Ex. #9. 

Relying on this definition, the Court found 

that the Act only required that employers 

ensure that their workplaces are safe, that is, 

that their workers are not exposed to 

‘‘significant risk[s] of harm.’’ 448 U.S. at 642. 

Second, the Court made clear that it is 

OSHA’s burden to establish that a significant 

risk is present at the current standard before 

lowering a PEL. The burden of proof is 

normally on the proponent, the Court noted, 

and there was no indication in the OSH Act 

that Congress intended to change this rule. 

448 U.S. at 653, 655. Thus, the Court held 

that, before promulgating a health standard, 

OSHA is required to make a ‘‘threshold 

finding that a place of employment is unsafe– 

in the sense that significant risks are present 

and can be eliminated or lessened by a 

change in practices’’ before it can adopt a 

new standard. Benzene, 448 U.S. at 642; Ex. 

#10. 

Although the Court declined to establish a 

set test for determining whether a workplace 

is unsafe, it did provide guidance on what 

constitutes a significant risk. The Court 

stated a significant risk was one that a 

reasonable person would consider significant 

and ‘‘take appropriate steps to decrease or 

eliminate.’’ Benzene, 448 U.S. at 655 (Ex. 

#10). For example, it said, a one in a 1,000 

risk would satisfy the requirement. However, 

this example was merely an illustration, not 

a hard line rule. The Court made it clear that 

determining whether a risk was ‘‘significant’’ 

was not a ‘‘mathematical straitjacket’’ and 

did not require the Agency to calculate the 

exact probability of harm. 448 U.S. at 655. 

OSHA was not required to support a 

significant risk finding ‘‘with anything 

approaching scientific certainty’’ and was 

free to use ‘‘conservative assumptions’’ in 

interpreting the evidence. 448 U.S. at 656. 

Still, because OSHA had not made a 

significant risk finding at the 10 ppm level 

(indeed, the Court characterized the evidence 

of leukemia in the record at the 10 ppm level 

as ‘‘sketch[y]’’), the Court vacated the new 

PEL and remanded the matter to OSHA. 

2. OSHA’s Post-Benzene Approach to 

Significant Risk and Air Contaminants 

In past rulemakings involving hazardous 

chemicals, OSHA satisfied its requirement to 

show that a significant risk of harm is present 

by estimating the risk to workers subject to 

a lifetime of exposure at various possible 

exposure levels. These estimates have 

typically been based on quantitative risk 

assessments. As a general policy, OSHA has 

considered a lifetime excess risk of one death 

or serious illness per 1000 workers associated 

with occupational exposure over a 45 year 

working life as clearly representing a 

significant risk. However, as noted above, 

Benzene does not require OSHA to use such 

a rigid or formulaic criterion. Nevertheless, 

OSHA has taken a conservative approach and 

has used the 1:1,000 example as a useful 

benchmark for determining significant risk. 

This approach has often involved the use of 

the quantitative risk assessment models 

OSHA has employed in developing 

substance-specific health standards. 

In the Air Contaminants rule, OSHA 

departed from this approach. Rather, as noted 

above, it looked at whether studies showed 

excess effects of concern at concentrations 

lower than allowed under OSHA’s existing 

standard. Where they did, OSHA made a 

significant risk finding and either set a PEL 

(where none existed previously) or lowered 

the existing PEL. These new PELs were based 

on agency judgment, taking into account the 

existing studies, and as appropriate, safety 

factors. Both industry and union petitioners 

challenged aspects of OSHA’s approach to 

making its significant risk determinations. 

The AFL–CIO argued that OSHA’s rule was 

‘‘systematically under protective,’’ and 

asserted that 16 of the exposure limits in the 

final rule were too high. For example, the 

AFL–CIO argued that OSHA had made a 

policy determination not to lower the PELs 

for carbon tetrachloride and vinyl bromide 

even though the exposure limits chosen 

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would continue to pose a residual risk in 

excess of 3.7 deaths per 1,000 workers 

exposed over the course of their working 

lifetime. The court agreed with the AFL–CIO, 

finding that OSHA failed to provide adequate 

evidence to support the higher PEL chosen 

by the agency. The court found that some of 

the PELs chosen by the Agency were at levels 

that would continue to pose a significant risk 

of material health impairment, and 

concluded that OSHA’s decision was due to 

time and resource constraints, rather than 

legitimate considerations, such as feasibility. 

Air Contaminants, 965 F.2d at 976–77; Ex. 

#8. 

Conversely, the American Iron and Steel 

Institute (AISI; Ex. #147) argued that OSHA 

set the PELs for certain substances below the 

level substantiated by the evidence. AISI 

argued that OSHA failed to quantify the risk 

of material health impairment at present 

exposure levels posed by individual 

substances and instead relied on assumptions 

in order to select its updated PELs. The court 

agreed with the AISI, finding that although 

OSHA summarized the studies on health 

effects in the final rule, it did not explain 

why the ‘‘studies mandated a particular PEL 

chosen.’’ Air Contaminants, 965 F.2d at 976. 

Specifically, the court stated that OSHA 

failed to quantify the risk from individual 

substances and merely provided conclusory 

statements that the new PEL would reduce a 

significant risk of material health effects. Air 

Contaminants, 965 F.2d at 975. 

OSHA argued to the court that it relied on 

safety factors in setting PELs. Safety or 

uncertainty factors are used to ensure that 

exposure limits for a hazardous substance are 

set sufficiently below the levels at which 

adverse effects have been observed to assure 

adequate protection for all exposed 

employees. As explained in the 1989 Air 

Contaminants rule, regulators use safety 

factors in this context to account for 

statistical limitations in studies showing no 

observed effects, the uncertainties in 

extrapolating effects observed in animals to 

humans, and variation in human responses. 

The size of the proper safety factor is a matter 

of professional judgment. 54 FR 2397–98 

The Eleventh Circuit rejected OSHA’s use 

of safety factors in the Air Contaminants rule, 

however. While noting that the Benzene case 

held that OSHA is permitted ‘‘to use 

conservative assumptions in interpreting data 

. . ., risking error on the side of 

overprotection rather than under protection,’’ 

Benzene, 448 U.S. at 656, the Air 

Contaminants court found that OSHA had 

not adequately supported the use of safety 

factors in this rule. The court observed that 

‘‘the difference between the level shown by 

the evidence and the final PEL is sometimes 

substantial,’’ and assumed that though ‘‘it is 

not expressly stated, that for each of those 

substances OSHA applied a safety factor to 

arrive at the final standard.’’ 965 F.2d at 978. 

OSHA had not indicated ‘‘how the existing 

evidence for individual substances was 

inadequate to show the extent of risk for 

these factors,’’ and ‘‘failed to explain the 

method by which its safety factors were 

determined.’’ Air Contaminants, 965 F.2d at 

978. ‘‘OSHA may use assumptions but only 

to the extent that those assumptions have 

some basis in reputable scientific evidence,’’ 

the court concluded. Air Contaminants, 965 

F.2d at 978–979. See Section IV. A. for 

additional discussion of the use of safety 

factors in risk assessment. 

Ultimately, although the Eleventh Circuit 

noted that OSHA ‘‘probably established that 

most or all of the substances involved do 

pose a significant risk at some level,’’ the 

court determined that OSHA failed to 

adequately explain or provide evidence to 

support its conclusion that ‘‘exposure to 

these substances at previous levels posed a 

significant risk . . . or that the new standard 

eliminates or reduces that risk to the extent 

feasible.’’ Air Contaminants, 965 F.2d at 987. 

Therefore, the court vacated the rule and 

remanded it to the agency. 

3. Material Impairment 

Under section 6(b)(5), OSHA must set 

standards to protect employees against 

‘‘material impairment of health or functional 

capacity.’’ This requirement was 

uncontroversial in Benzene, since the effect 

on which OSHA regulated was leukemia. 

However, in Air Contaminants, AISI argued 

that not all of the health effects addressed by 

OSHA in the final rule were material health 

effects. Specifically, AISI stated that the 

category of ‘‘sensory irritation,’’ which OSHA 

used as an endpoint to set PELs for 79 

substances, failed to distinguish between 

‘‘materially impairing sensory irritation and 

the less serious sort.’’ AISI brief at page 24. 

The court rejected AISI’s argument. It 

accepted OSHA’s explanation that material 

impairments may be any health effect, 

permanent or transitory, that seriously 

threatens the health or job performance of an 

employee, and held that, ‘‘OSHA is not 

required to state with scientific certainty or 

precision the exact point at which each type 

of sensory or physical irritation becomes a 

material impairment.’’ Air Contaminants, 965 

F.2d at 975. ‘‘Section 6(b)(5) of the [OSH] Act 

charges OSHA with addressing all forms of 

‘material impairment of health or functional 

capacity,’’ and not exclusively those causing 

‘death or serious physical harm’ or ‘grave 

danger’ from exposure to toxic substances, 

the court held. Air Contaminants, 965 F.2d 

at 975; Ex. #8. 

D. Technological and Economic Feasibility 

Once OSHA makes its threshold finding 

that a significant risk is present at the current 

PEL or in the absence of a PEL and can be 

reduced or eliminated by a standard, the 

Agency considers feasibility. First, the 

feasibility requirement that originated in 

Section 6(b)(5) of the OSH Act requires that 

the standard be ‘‘technologically feasible,’’ 

which generally means an industry has to be 

able to develop the technology necessary to 

comply with the requirements in the 

standard. Lead I, 647 F.2d at 1264–65; Ex. 

#12. 

Second, the standard must be 

‘‘economically feasible,’’ meaning that an 

industry as a whole must be able to absorb 

the impact of the costs associated with 

compliance with the standard. Id. at 1265. 

OSHA has historically made determinations 

on technological feasibility and economic 

feasibility separately. 

1. Technological Feasibility 

A standard is technologically feasible if ‘‘a 

typical firm will be able to develop and 

install engineering and work practice 

controls that can meet the PEL in most 

operations.’’ Lead I, 647 F.2d at 1272. 

Standards are permitted to be ‘‘technology 

forcing,’’ meaning that OSHA can require 

industries to ‘‘develop new technology’’ or 

‘‘impose a standard which only the most 

technologically advanced plants in an 

industry have been able to achieve, even if 

only in some of their operations some of the 

time.’’ Lead I, 647 F.2d at 1264; Ex. #12. 

Technological feasibility analysis generally 

focuses on demonstrating that PELs can be 

achieved through engineering and work 

practice controls. However, the concept of 

technological feasibility applies to all aspects 

of the standard, including air monitoring, 

housekeeping, and respiratory protection 

requirements. Some courts have required 

OSHA to determine whether a standard is 

technologically feasible on an industry-byindustry basis, Color Pigments Manufacturers 

Assoc. v. OSHA, 16 F.3d 1157 (Ex. #13), 

1162–63 (11th Cir. 1994); Air Contaminants, 

965 F.2d at 981–82 (Ex. #8), while another 

court has upheld technological feasibility 

findings based on the nature of an activity 

across many industries rather than on a pure 

industry basis, Public Citizen Health 

Research Group v. United States Department 

of Labor, 557 F.3d 165,178–79 (3d Cir. 2009; 

Ex. #14). 

Regardless, OSHA must show the existence 

of ‘‘technology that is either already in use 

or has been conceived and is reasonably 

capable of experimental refinement and 

distribution within the standard’s 

deadlines,’’ Lead I, 647 F.2d 1272. Where the 

agency presents ‘‘substantial evidence that 

companies acting vigorously and in good 

faith can develop the technology,’’ the agency 

is not bound to the technological status quo, 

and ‘‘can require industry to meet PELs never 

attained anywhere.’’ Lead I, 647 F.2d 1265; 

Ex. #12. 

OSHA usually demonstrates the 

technological feasibility of a PEL by finding 

establishments in which the PEL is already 

being met and identifying the controls in use, 

or by arguing that even if the PEL is not 

currently being met in a given operation, the 

PEL could be met with specific additional 

controls. OSHA is also concerned with 

determining whether the conditions under 

which the PEL can be met in specific plants 

are generalizable to an industry as whole. 

This approach is very resource-intensive, as 

it commonly requires gathering detailed 

information on exposure levels and controls 

for each affected operation and process in an 

industry. OSHA’s inspection databases 

usually do not record this information, and 

consequently OSHA makes site visits for the 

specific purpose of determining 

technological feasibility. (See Section IV. of 

this Request for Information for a detailed 

discussion of how OSHA determines 

technological feasibility and possible 

alternatives to current methods.) 

As noted above, in the Air Contaminants 

rule, OSHA made its feasibility 

determination by gathering information on 

work processes that might expose workers 

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61424 Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 

above the new PELs, and identifying controls 

that had been successfully implemented to 

reduce the exposure to the new limits. It 

made these findings mainly at the two-digit 

SIC level, but also at the three- and four-digit 

level where appropriate given the processes 

involved. The Air Contaminants court 

rejected this approach, finding that OSHA 

failed to make industry-specific findings or 

identify the specific technologies capable of 

meeting the proposed limit in industryspecific operations. Air Contaminants, 965 

F.2d at 981. While OSHA had identified 

primary air contaminant control methods: 

engineering controls, administrative controls 

and work practices and personal protective 

equipment, the agency, ‘‘only provided a 

general description of how the generic 

engineering controls might be used in the 

given sector.’’ Air Contaminants, 965 F.2d at 

981. Though noting that OSHA need only 

provide evidence sufficient to justify a 

‘‘general presumption of feasibility,’’ the 

court held that this ‘‘does not grant OSHA 

license to make overbroad generalities as to 

feasibility or to group large categories of 

industries together without some explanation 

of why findings for the group adequately 

represents the different industries in that 

group.’’ Air Contaminants, 965 F.2d at 981– 

82. Accordingly, the court held that OSHA 

failed to establish the technological 

feasibility of the new PELs in its final rule. 

Air Contaminants, 965 F.2d at 982. As noted 

below, in a subsequent rulemaking the 

reviewing court accepted OSHA’s approach 

of grouping numbers of industries. 

2. Economic Feasibility 

With respect to economic feasibility, the 

courts have stated ‘‘A standard is feasible if 

it does not threaten ‘‘massive dislocation’’ to 

. . . or imperil the existence of the industry.’’ 

United Steelworkers v. Marshall, 647 F.2d 

1189, 1265 (D.C. Cir. 1980) Lead I,). In order 

to show this, the same court suggested, 

OSHA should ‘‘construct a reasonable 

estimate of compliance costs and 

demonstrate a reasonable likelihood that 

these costs will not threaten the existence or 

competitive structure of an industry.’’ The 

same court noted, ‘‘[T]he court probably 

cannot expect hard and precise estimates of 

costs. Nevertheless, the agency must of 

course provide a reasonable assessment of 

the likely range of costs of its standard, and 

the likely effects of those costs on the 

industry.’’ Lead I, 647 F.2d at 1265; Ex. #12. 

Economic feasibility does not entail a costbenefit analysis of the level of protection 

provided by the standard. As the Supreme 

Court noted, Congress considered the costs of 

creating a safe and healthful workplace to be 

the cost of doing business. Cotton Dust, 452 

U.S. at 514, 520; Ex. #15. Instead, standards 

are economically feasible if the standard will 

not substantially alter the industry’s 

competitive structure. Forging Indus. Ass’n v. 

Secretary of Labor, 773 F.2d 1436, 1453 (4th 

Cir. 1985; Ex. #148). In order to make a 

determination of economic feasibility, OSHA 

should ‘‘construct a reasonable estimate of 

compliance costs and demonstrate a 

reasonable likelihood that these costs will 

not threaten the existence or competitive 

structure of an industry,’’ Lead I, 647 F.2d at 

1272, noting that such analyses will not 

provide absolute certainty: 

[T]he court probably cannot expect hard 

and precise estimates of costs. Nevertheless, 

the agency must of course provide a 

reasonable assessment of the likely range of 

costs of its standard, and the likely effects of 

those costs on the industry . . . . And OSHA 

can revise any gloomy forecast that estimated 

costs will imperil an industry by allowing for 

the industry’s demonstrated ability to pass 

through costs to consumers. 647 F.2d at 

1266–67. 

Again, courts have required OSHA to 

determine whether a standard is 

economically feasible on an industry-byindustry basis. See Air Contaminants, 965 

F.2d at 982 (Ex. #8). Both to meet 

requirements for any Regulatory Flexibility 

Act (5 U.S.C. 603, 604) analysis and to assure 

that standards do not threaten the 

competitive structure of an industry, OSHA 

also analyzes the economic impacts on 

different size classes within an industry. 

However, OSHA is not required to show that 

all companies within an industry will be able 

to bear the burden of compliance or 

‘‘guarantee the continued existence of 

individual employers.’’ Lead I, 647 F.2d at 

1265 (Ex. #12) (quoting Industrial Union 

Dep’t, AFL–CIO v. Hodgson, 499 F.2d 467, 

478 (D.C. Cir. 1974) Ex. #55)). 

As discussed above, OSHA supported its 

economic feasibility findings for the 1989 Air 

Contaminants rule based primarily on the 

results of a survey of over 5700 businesses, 

summarizing the projected cost of 

compliance at the two-digit SIC industry 

sector level. It found that compliance costs 

would average less than one percent of 

profits, and, alternatively, that prices would 

increase by less than one half percent. 

Nonetheless, the Eleventh Circuit held that 

OSHA had failed to meet its burden. The 

court held that OSHA was required to show 

that the rule was economically feasible on an 

industry-by industry basis, and that OSHA 

had not shown that its analyses at the twodigit SIC industry sector level were 

appropriate to meet this burden. Air 

Contaminants, 965 F.2d at 982. OSHA argued 

the generic nature of the rulemaking allowed 

the agency ‘‘a great latitude in grouping 

industries in order to estimate ‘average’ 

costs,’’ and that ‘‘the costs were sufficiently 

low per sector to demonstrate feasibility not 

only for each sector, but each sub-sector.’’ Air 

Contaminants, 965 F.2d at 983. However, the 

court found that ‘‘average estimates of cost 

can be extremely misleading in assessing the 

impact of particular standards on individual 

industries’’ and observed that ‘‘analyzing the 

economic impact for an entire sector could 

conceal particular industries laboring under 

special disabilities and likely to fail as a 

result of enforcement.’’ Air Contaminants, 

965 F.2d at 982. The court allowed that 

OSHA could ‘‘find and explain that certain 

impacts and standards do apply to entire 

sectors of an industry’’ if ‘‘coupled with a 

showing that there are no disproportionately 

affected industries within the group.’’ Air 

Contaminants, 965 F.2d at 982 n.28. But in 

this case, the court found, OSHA had not 

explained why its use of such a ‘‘broad 

grouping was appropriate.’’ Air 

Contaminants, 965 F.2d at 983; Ex. #8. 

Ultimately, the court held that OSHA did 

not sufficiently explain or support its 

threshold determination that exposures 

above the new PELs posed significant risks 

of material health impairment, or that the 

new PELs eliminated or reduced the risks to 

the extent feasible. Finding that ‘‘OSHA’s 

overall approach to this rulemaking is . . . 

flawed,’’ the court vacated the entire Air 

Contaminant rulemaking, rather than just the 

23 chemicals that were contested by union 

and industry representatives. Air 

Contaminants, 965 F.2d at 987(Ex. #8). 

The Eleventh Circuit denied OSHA’s 

petition for rehearing. No longer having a 

basis to enforce the 1989 PELs, OSHA 

directed its compliance officers to stop 

enforcing the updated limits through a 

memo, which was followed by a Federal 

Register Notice on June 30, 1993, revoking 

the new limits. 58 FR 35338–35351; (Ex. 

#19). 

Appendix B: 1989 PELs Table 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Acetaldehyde ...................................................................... 75–07–0 ............... 100 180 150 270 ................ ................ ................

Acetic acid .......................................................................... 64–19–7 ............... 10 25 ................ ................ ................ ................ ................

Acetic anhydride ................................................................. 108–24–7 ............. ................ ................ ................ ................ 5 20 ................

Acetone .............................................................................. 67–64–1 ............... 750 1800 1000 24006 ................ ................ ................

Acetonitrile .......................................................................... 75–05–8 ............... 40 70 60 105 ................ ................ ................

2-Acetylamino-fluorine; see 1910.1014 .............................. 53–96–3.

Acetylene dichloride; see 1,2-Dichloroethylene ................. 540–59–0.

Acetylene tetrabromide ...................................................... 79–27–6 ............... 1 14 ................ ................ ................ ................ ................

Acetylsalicylic acid (Aspirin) ............................................... 50–78–2 ............... ................ 5 ................ ................ ................ ................ ................

Acrolein ............................................................................... 107–02–8 ............. 0.1 0.25 0.3 0.8 ................ ................ ................

Acrylamide .......................................................................... 79–06–1 ............... ................ 0.03 ................ ................ ................ ................ X 

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TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Acrylic acid ......................................................................... 79–10–7 ............... 10 30 ................ ................ ................ ................ X 

Acrylonitrile; see 1910.1045 ............................................... 107–13–1 ............. ................ ................ ................ ................ ................ ................ ................

Aldrin .................................................................................. 309–00–2 ............. ................ 0.25 ................ ................ ................ ................ X 

Allyl alcohol ........................................................................ 107–18–6 ............. 2 5 4 10 ................ ................ X 

Allyl chloride ....................................................................... 107–05–1 ............. 1 3 2 6 ................ ................ ................

Allyl glycidyl ether (AGE) ................................................... 106–92–3 ............. 5 22 10 44 ................ ................ ................

Allyl propyl disulfide ............................................................ 2179–59–1 ........... 2 12 3 18 ................ ................ ................

alpha-Alumina ..................................................................... 1344–28–1 ........... ................ ................ ................ ................ ................ ................ ................

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Aluminum (as Al) Metal ...................................................... 7429–90–5. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Pyro powders ....... ................ 5 ................ ................ ................ ................ ................

Welding fumes ..... ................ 5 ................ ................ ................ ................ ................

Soluble salts ......... ................ 2 ................ ................ ................ ................ ................

Alkyls .................... ................ 2 ................ ................ ................ ................ ................

4-Aminodiphenyl; see 1910.1011 ....................................... 92–67–1. 

2-Aminoethanol; see Ethanolamine ................................... 141–43–5. 

2-Aminopyridine .................................................................. 504–29–0 ............. 0.5 2 ................ ................ ................ ................ ................

Amitrole .............................................................................. 61–82–5 ............... ................ 0.2 ................ ................ ................ ................ ................

Ammonia ............................................................................ 7664–41–7 ........... ................ ................ 35 27 ................ ................ ................

Ammonium chloride fume .................................................. 12125–02–9 ......... ................ 10 ................ 20 ................ ................ ................

Ammonium sulfamate ......................................................... 7773–06–0. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

n-Amyl acetate ................................................................... 628–63–7 ............. 100 525 ................ ................ ................ ................ ................

Sec-Amyl acetate ............................................................... 626–38–0 ............. 125 650 ................ ................ ................ ................ ................

Aniline and homologs ......................................................... 62–53–3 ............... 2 8 ................ ................ ................ ................ X 

Anisidine (o-, p-isomers) .................................................... 29191–52–4 ......... ................ 0.5 ................ ................ ................ ................ ................

Antimony and compounds (as Sb) ..................................... 7440–36–0 ........... ................ 0.5 ................ ................ ................ ................ ................

ANTU (alpha naphthyl-thiourea) ........................................ 86–88–4 ............... ................ 0.3 ................ ................ ................ ................ ................

Arsenic, organic compounds (as As) ................................. 7440–38–2 ........... ................ 0.5 ................ ................ ................ ................ ................

Arsenic, inorganic compounds (as As); see 1910.1018 .... Varies with compound................. ................ ................ ................ ................ ................ ................

Arsine ................................................................................. 7784–42–1 ........... 0.05 0.2 ................ ................ ................ ................ ................

Asbestos; see 1910.1001 ................................................... Varies ................... ................ ................ ................ ................ ................ ................ ................

Atrazine .............................................................................. 1912–24–9 ........... ................ 5 ................ ................ ................ ................ ................

Azinphos-methyl ................................................................. 86–50–0 ............... ................ 0.2 ................ ................ ................ ................ X 

Barium, soluble compounds ............................................... 7440–39–3 ........... ................ 0.5 ................ ................ ................ ................ ................

Barium sulfate .................................................................... 7727–43–7. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Benomyl .............................................................................. 17804–35–2. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Benzene; see 1910.1028. See Table Z–2 for the limits 

applicable in the operations or sectors excluded in 

1910.1028.

71–43–2. 

Benzidine; see 1910.1010 .................................................. 92–87–5. 

p-Benzoquinone; see Quinone ........................................... 106–51–4. 

Benzo(a)pyrene; see Coal tar pitch volatiles 

Benzoyl peroxide ................................................................ 94–36–0 ............... ................ 5 ................ ................ ................ ................ ................

Benzyl chloride ................................................................... 100–44–7 ............. 1 5 ................ ................ ................ ................ ................

Beryllium and beryllium compounds (as Be) ..................... 7440–41–7 ........... 0.002 ................ 1.005 ................ 0.025 ................ ................

Biphenyl; see Diphenyl ....................................................... 92–52–4. 

Bismuth telluride, undoped ................................................. 1304–82–1. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Bismuth telluride, Se-doped ............................................... 1304–82–1 ........... ................ 5 ................ ................ ................ ................ ................

Borates, tetra, sodium salts: 

Anhydrous ................................................................... 1330–43–4 ........... ................ ................ 10 ................ ................ ................ ................

Decahydrate ................................................................ 1303–96–4 ........... ................ ................ 10 ................ ................ ................ ................

Penta-hydrate .............................................................. 12179–04–3 ......... ................ ................ 10 ................ ................ ................ ................

Boron oxide ........................................................................ 1303–86–2. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable Fraction................. 5 ................ ................ ................ ................ ................

Boron tribromide ................................................................. 10294–33–4 ......... ................ ................ ................ ................ 1 10 ................

Boron trifluoride .................................................................. 7637–07–2 ........... ................ ................ ................ ................ 1 3 ................

Bromacil .............................................................................. 314–40–9 ............. 1 10 ................ ................ ................ ................ ................

Bromine .............................................................................. 7726–95–6 ........... 0.1 0.7 0.3 2 ................ ................ ................

Bromine pentafluoride ........................................................ 7789–30–2 ........... 0.1 0.7 ................ ................ ................ ................ ................

Bromoform .......................................................................... 75–25–2 ............... 0.5 5 ................ ................ ................ ................ X 

Butadiene (1,3- Butadiene); see 1910.1051 ...................... 106–99–0. 

Butane ................................................................................ 106–97–8 ............. 800 1900 ................ ................ ................ ................ ................

Butanethiol; see Butyl mercaptan ...................................... 109–79–5. 

2-Butanone (Methyl ethyl ketone) ...................................... 78–93–3 ............... 200 590 300 885 ................ ................ ................

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TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

2-Butoxyethanol .................................................................. 111–76–2 ............. 25 120 ................ ................ ................ ................ X 

n-Butyl-acetate ................................................................... 123–86–4 ............. 150 710 200 950 ................ ................ ................

sec-Butyl acetate ................................................................ 105–46–4 ............. 200 950 ................ ................ ................ ................ ................

tert-Butyl acetate ................................................................ 540–88–5 ............. 200 950 ................ ................ ................ ................ ................

Butyl acrylate ...................................................................... 141–32–2 ............. 10 55 ................ ................ ................ ................ ................

n-Butyl alcohol .................................................................... 71–36–3 ............... ................ ................ ................ ................ 50 150 X 

sec-Butyl alcohol ................................................................ 78–92–2 ............... 100 305 ................ ................ ................ ................ ................

tert-Butyl alcohol ................................................................. 75–65–0 ............... 100 300 150 450 ................ ................ ................

Butylamine .......................................................................... 109–73–9 ............. ................ ................ ................ ................ 5 15 X 

tert-Butyl Chromate (as CrO3) ........................................... 1189–85–1 ........... ................ ................ ................ ................ ................ 0.1 X 

n-Butyl glycidyl ether (BGE) ............................................... 2426–08–6 ........... 25 135 ................ ................ ................ ................ ................

n-Butyl lactate ..................................................................... 138–22–7 ............. 5 25 ................ ................ ................ ................ ................

Butyl mercaptan ................................................................. 109–79–5 ............. 0.5 1.5 ................ ................ ................ ................ ................

o-sec-Butylphenol ............................................................... 89–72–5 ............... 5 30 ................ ................ ................ ................ X 

p-tert-Butyltoluene .............................................................. 98–51–1 ............... 10 60 20 120 ................ ................ ................

Cadmium (all forms, as Cd); see 1910.1027 See Table 

Z–2 for the limits applicable in the operations or sectors excluded in 1910.1027.

7440–43–9. 

Calcium carbonate ............................................................. 1317–65–3. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Calcium cyanamide ............................................................ 156–62–7 ............. ................ 0.5 ................ ................ ................ ................ ................

Calcium hydroxide; see particulates not otherwise regulated.1305–62–0 ........... ................ 5 ................ ................ ................ ................ ................

Calcium oxide ..................................................................... 1305–78–8 ........... ................ 5 ................ ................ ................ ................ ................

Calcium silicate .................................................................. 1344–95–2 ........... ................ ................ ................ ................ ................ ................ ................

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Calcium sulfate ................................................................... 7778–18–9. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Camphor, synthetic ............................................................ 76–22–2. 

Camphor, synthetic ............................................................ 76–22–2 ............... ................ 2 ................ ................ ................ ................ ................

Caprolactam ....................................................................... 105–60–2. 

Dust ...................... ................ 1 ................ 3 ................ ................ ................

Vapor .................... 5 20 10 40 ................ ................ ................

Captafol (Difolatan®) .......................................................... 2425–06–1 ........... ................ 0.1 ................ ................ ................ ................ ................

Captan ................................................................................ 133–06–2 ............. ................ 5 ................ ................ ................ ................ ................

Carbaryl (Sevin®) ............................................................... 63–25–2 ............... ................ 5 ................ ................ ................ ................ ................

Carbofuran (Furadan®) ...................................................... 1563–66–2 ........... ................ 0.1 ................ ................ ................ ................ ................

Carbon black ...................................................................... 1333–86–4 ........... ................ 3.5 ................ ................ ................ ................ ................

Carbon dioxide ................................................................... 124–38–9 ............. 10,000 18,000 30,000 

0 

54,000 

0 

................ ................ ................

Carbon disulfide ................................................................. 75–15–0 ............... 4 12 12 36 ................ ................ X 

Carbon monoxide ............................................................... 630–08–0 ............. 35 40 ................ ................ 200 229 ................

Carbon tetrabromide .......................................................... 558–13–4 ............. 0.1 1.4 0.3 4 ................ ................ ................

Carbon tetrachloride ........................................................... 56–23–5 ............... 2 12.6 ................ ................ ................ ................ ................

Carbonyl fluoride ................................................................ 353–50–4 ............. 2 5 5 15 ................ ................ ................

Catechol (Pyrocatechol) ..................................................... 120–80–9 ............. 5 20 ................ ................ ................ ................ X 

Cellulose ............................................................................. 9004–34–6. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Cesium hydroxide ............................................................... 21351–79–1 ......... ................ 2 ................ ................ ................ ................ ................

Chlordane ........................................................................... 57–74–9 ............... ................ 0.5 ................ ................ ................ ................ X 

Chlorinated camphene ....................................................... 8001–35–2 ........... ................ 0.5 ................ 1 ................ ................ X 

Chlorinated diphenyl oxide ................................................. 55720–99–5 ......... ................ 0.5 ................ ................ ................ ................ ................

Chlorine .............................................................................. 7782–50–5 ........... 0.5 1.5 1 3 ................ ................ ................

Chlorine dioxide .................................................................. 10049–04–4 ......... 0.1 0.3 0.3 0.9 ................ ................ ................

Chlorine trifluoride .............................................................. 7790–91–2 ........... ................ ................ ................ ................ 0.1 0.4 ................

Chloro-acetaldehyde .......................................................... 107–20–0 ............. ................ ................ ................ ................ 1 3 ................

alpha-Chloroaceto-phenone (Phenacy1 chloride) .............. 532–27–4 ............. 0.05 0.3 ................ ................ ................ ................ ................

Chloroacetyl chloride .......................................................... 79–04–9 ............... 0.05 0.2 ................ ................ ................ ................ ................

Chlorobenzene ................................................................... 108–90–7 ............. 75 350 ................ ................ ................ ................ ................

o-Chloro-benzylidene malononitrile .................................... 2698–41–1 ........... ................ ................ ................ ................ 0.05 0.4 X 

Chloro-bromomethane ........................................................ 74–97–5 ............... 200 1050 ................ ................ ................ ................ ................

2-Chloro-1,3-butadiene; see beta-Chloroprene ................. 126–99–8 ............. ................ ................ ................ ................ ................ ................ ................

Chloro-difluoromethane ...................................................... 75–45–6 ............... 1000 3500 ................ ................ ................ ................ ................

Chlorodiphenyl (42% Chlorine) (PCB) ............................... 53469–21–9 ......... ................ 1 ................ ................ ................ ................ X 

Chlorodiphenyl (54% Chlorine) (PCB) ............................... 11097–69–1 ......... ................ 0.5 ................ ................ ................ ................ X 

1-Chloro,2,3-epoxypropane; see Epichlorohydrin .............. 106–89–8. 

2-Chloroethanol; see Ethylene chlorohydrin ...................... 107–07–3. 

Chloroethylene; see Vinyl chloride ..................................... 75–01–4. 

Chloroform (Trichloro-methane) ......................................... 67–66–3 ............... 2 9.78 ................ ................ ................ ................ ................

bis(Chloro-methyl) ether; see 1910.1008 ........................... 542–88–1. 

Chloromethyl methyl ether; see 1910.1006 ....................... 107–30–2. 

1-Chloro-l-nitropropane ...................................................... 600–25–9 ............. 2 10 ................ ................ ................ ................ ................

Chloropenta-fluoroethane ................................................... 76–15–3 ............... 1000 6320 ................ ................ ................ ................ ................

Chloropicrin ........................................................................ 76–06–2 ............... 0.1 0.7 ................ ................ ................ ................ ................

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 61427 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

beta-Chloroprene ................................................................ 126–99–8 ............. 10 35 ................ ................ ................ ................ X 

o-Chlorostyrene .................................................................. 2039–87–4 ........... 50 285 75 428 ................ ................ ................

o-Chlorotoluene .................................................................. 95–49–8 ............... 50 250 ................ ................ ................ ................ ................

2-Chloro-6-trichloro-methyl pyridine ................................... 1929–82–4. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Chlorpyrifos ........................................................................ 2921–88–2 ........... ................ 0.2 ................ ................ ................ ................ X 

Chromic acid and chromates (as CrO3); see 1910.1026. 

See Table Z–2 for the exposure limit for any operations 

or sectors where the exposure limit in 1910.1026 is 

stayed or are otherwise not in effect.

Varies with compound................. ................ ................ ................ 0.1 ................ ................

Chromium (II) compounds (as Cr) ..................................... Varies with compound................. 0.5 ................ ................ ................ ................ ................

Chromium (III) compounds (as Cr) .................................... Varies with compound................. 0.5 ................ ................ ................ ................ ................

Chromium metal and insoluble salts .................................. 7440–47–3 ........... ................ 1 ................ ................ ................ ................ ................

Chrysene; see Coal tar pitch volatiles 

Clopidol ............................................................................... 2971–90–6. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Coal dust (less than 5% Si02), quartz, respirable fraction N/A ....................... ................ 2 ................ ................ ................ ................ ................

Coal dust (greater than or equal to 5% Si02) respirable 

quartz fraction.

N/A ....................... ................ 0.1 ................ ................ ................ ................ ................

Coal tar pitch volatiles (benzene soluble fraction), anthracene, BaP, phenanthrene, acridine, chrysene, pyrene.8007–45–2 ........... ................ 0.2 ................ ................ ................ ................ ................

Cobalt metal, dust, and fume (as Co) ................................ 7440–48–4 ........... ................ 0.05 ................ ................ ................ ................ ................

Cobalt carbonyl (as Co) ..................................................... 10210–68–1 ......... ................ 0.1 ................ ................ ................ ................ ................

Cobalt hydrocarbonyl (as Co) ............................................ 16842–03–8 ......... ................ 0.1 ................ ................ ................ ................ ................

Coke oven emissions; See 1910.1029 

Copper ................................................................................ 7440–50–8. 

Fume (as Cu) ....... ................ 0.1 ................ ................ ................ ................ ................

Dusts and mists 

(as Cu).

................ 1 ................ ................ ................ ................ ................

Cotton dust, raw This 8-hour TWA applies to respirable 

dust as measured by a vertical elutriator cotton dust or 

equivalent instrument. The time-weighted average applies to the cotton waste processing operations of 

waster recycling (sorting, blending, cleaning, and 

willowing) and garnetting. See also 1910.1043 for cotton dust limits applicable to other sectors. 

Crag herbicide (Sesone) .................................................... 136–78–7. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Cresol, all isomers .............................................................. 1319–77–3; 95– 

48–7; 108–39–4; 

106–44–5.

5 22 ................ ................ ................ ................ X 

Crotonaldehyde .................................................................. 123–73–9; 4170– 

30–3.

................ 2 6 ................ ................ ................ ................

Crufomate ........................................................................... 106–44–5 ............. ................ 5 ................ ................ ................ ................ ................

Cumene .............................................................................. 98–82–8 ............... 50 245 ................ ................ ................ ................ X 

Cyanamide ......................................................................... 420–04–2 ............. ................ 2 ................ ................ ................ ................ ................

Cyanides (as CN) ............................................................... 151–50–0 ............. ................ 5 ................ ................ ................ ................ ................

Cyanogen ........................................................................... 460–19–5 ............. 10 20 ................ ................ ................ ................ ................

Cyanogen chloride ............................................................. 506–77–4 ............. ................ ................ ................ ................ 0.3 0.6 ................

Cyclohexane ....................................................................... 110–82–7 ............. 300 1050 ................ ................ ................ ................ ................

Cyclohexanol ...................................................................... 108–93–0 ............. 50 200 ................ ................ ................ ................ X 

Cyclohexanone ................................................................... 108–94–1 ............. 25 100 ................ ................ ................ ................ X 

Cyclohexene ....................................................................... 110–83–8 ............. 300 1015 ................ ................ ................ ................ ................

Cyclohexylamine ................................................................ 108–91–8 ............. 10 40 ................ ................ ................ ................ ................

Cyclonite ............................................................................. 121–82–4 ............. ................ 1.5 ................ ................ ................ ................ X 

Cyclopentadiene ................................................................. 542–92–7 ............. 75 200 ................ ................ ................ ................ ................

Cyclopentane ...................................................................... 287–92–3 ............. 600 1720 ................ ................ ................ ................ ................

Cyhexatin ............................................................................ 13121–70–5 ......... ................ 5 ................ ................ ................ ................ ................

2,4–D (Dichlorophenoxy-acetic acid) ................................. 94–75–7 ............... ................ 10 ................ ................ ................ ................ ................

Decaborane ........................................................................ 17702–41–9 ......... 0.05 0.3 0.15 0.9 ................ ................ X 

Demeton-(Systox®) ............................................................ 8065–48–3 ........... ................ 0.1 ................ ................ ................ ................ X 

Diborane ............................................................................. 19207–45–7 ......... 0.1 0.1 ................ ................ ................ ................ ................

Dichlorodiphenyltri-chloroethane (DDT) ............................. 50–29–3 ............... ................ 1 ................ ................ ................ ................ X 

Dichlorvos (DDVP) ............................................................. 62–73–7 ............... ................ 1 ................ ................ ................ ................ X 

Diacetone alcohol (4-Hydroxy-4-methyl-2-pentanone) ...... 123–42–2 ............. 50 240 ................ ................ ................ ................ ................

1,2-Diaminoethane; see Ethylenediamine ......................... 107–15–3. 

Diazinon .............................................................................. 333–41–5 ............. ................ 0.1 ................ ................ ................ ................ X 

Diazomethane .................................................................... 334–88–3 ............. 0.2 0.4 ................ ................ ................ ................ ................

1,2-Dibromo-3-chloropropane; see 1910.1044 .................. 96–12–8. 

2–N-Dibutylamino-ethanol .................................................. 102–81–8 ............. 2 14 ................ ................ ................ ................ ................

Dibutyl phosphate ............................................................... 107–66–4 ............. 1 5 2 10 ................ ................ ................

Dibutyl phthalate ................................................................. 84–74–2 ............... ................ 5 ................ ................ ................ ................ ................

Dichloro-acetylene .............................................................. 7572–29–4 ........... ................ ................ ................ ................ 0.1 0.4 ................

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

61428 Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

o-Dichlorobenzene ............................................................. 95–50–1 ............... ................ ................ ................ ................ 50 300 ................

p-Dichlorobenzene ............................................................. 106–46–7 ............. 75 450 110 675 ................ ................ ................

3,3′-Dichloro-benzidine; see 1910.1007 ............................ 91–94–1. 

Dichlorodifluoro-methane ................................................... 75–71–8 ............... 1000 4950 ................ ................ ................ ................ ................

1,3-Dichloro-5,5-dimethyl hydantoin ................................... 118–52–5 ............. ................ 0.2 ................ 0.4 ................ ................ ................

1,1-Dichloroethane ............................................................. 75–34–3 ............... 100 400 ................ ................ ................ ................ ................

1,2-Dichloroethylene ........................................................... 540–59–0 ............. 200 790 ................ ................ ................ ................ ................

Dichloroethyl ether ............................................................. 111–44–4 ............. 5 30 10 60 ................ ................ X 

Dichloro-methane; see Methylene chloride ........................ 75–09–2. 

Dichloromono-fluoromethane ............................................. 75–43–4 ............... 10 40 ................ ................ ................ ................ ................

1,1-Dichloro- 1-nitroethane ................................................. 594–72–9 ............. 2 10 ................ ................ ................ ................ ................

1,2-Dichloropropane; see Propylene dichloride ................. 78–87–5. 

1,3-Dichloropropene ........................................................... 542–75–6 ............. 1 5 ................ ................ ................ ................ X 

2,2-Dichloro-propionic acid ................................................. 75–99–0 ............... 1 6 ................ ................ ................ ................ ................

Dichloro-tetrafluoroethane .................................................. 76–14–2 ............... 1000 7000 ................ ................ ................ ................ ................

Dicrotophos ........................................................................ 141–66–2 ............. ................ 0.25 ................ ................ ................ ................ X 

Dicyclo-pentadiene ............................................................. 77–73–6 ............... 5 30 ................ ................ ................ ................ ................

Dicyclo-pentadienyl iron ..................................................... 102–54–5. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Dieldrin ............................................................................... 60–57–1 ............... ................ 0.25 ................ ................ ................ ................ X 

Diethanolamine ................................................................... 111–42–2 ............. 3 15 ................ ................ ................ ................ ................

Diethylamine ....................................................................... 109–89–7 ............. 10 30 25 75 ................ ................ ................

2-Diethylamino-ethanol ....................................................... 100–37–8 ............. 10 50 ................ ................ ................ ................ ................

Diethylene triamine ............................................................. 111–40–0 ............. 1 4 ................ ................ ................ ................ ................

Diethyl ether; see Ethyl ether ............................................. 60–29–7. 

Diethyl ketone ..................................................................... 96–22–0 ............... 200 705 ................ ................ ................ ................ ................

Diethyl phthalate ................................................................. 84–66–2 ............... ................ 5 ................ ................ ................ ................ ................

Difluorodibromo-methane ................................................... 75–61–6 ............... 100 860 ................ ................ ................ ................ ................

Diglycidyl ether (DGE) ........................................................ 2238–07–5 ........... 0.1 0.5 ................ ................ ................ ................ ................

Dihydroxy-benzene; see Hydroquinone ............................. 123–31–9. 

Diisobutyl ketone ................................................................ 108–83–8 ............. 25 150 ................ ................ ................ ................ ................

Diisopropylamine ................................................................ 108–18–9 ............. 5 20 ................ ................ ................ ................ X 

4-Dimethylamino-azobenzene; see 1910.1015 .................. 60–11–7. 

Dimethoxy-methane; see Methylal ..................................... 109–87–5. 

Dimethyl acetamide ............................................................ 127–19–5 ............. 10 35 ................ ................ ................ ................ X 

Dimethylamine .................................................................... 124–40–3 ............. 10 18 ................ ................ ................ ................ ................

Dimethylamino-benzene; see Xylidine ............................... 1300–73–8. 

Dimethylaniline (N,N-Dimethylaniline) ................................ 121–69–7 ............. 5 25 10 50 ................ ................ X 

Dimethyl-benzene; see Xylene .......................................... Varies with isomer. 

Dimethyl-1,2-dibromo-2,2-dichloroethyl phosphate ............ 300–76–5 ............. ................ 3 ................ ................ ................ ................ X 

Dimethyl-formamide ........................................................... 68–12–2 ............... 10 30 ................ ................ ................ ................ X 

2,6-Dimethyl-4-heptanone; see Diisobutyl ketone ............. 108–83–8. 

1,1-Dimethyl-hydrazine ....................................................... 57–14–7 ............... 0.5 1 ................ ................ ................ ................ X 

Dimethyl-phthalate .............................................................. 131–11–3 ............. ................ 5 ................ ................ ................ ................ ................

Dimethyl sulfate .................................................................. 77–78–1 ............... 0.1 0.5 ................ ................ ................ ................ X 

Dinitolmide (3,5-Dinitro-o-toluamide) .................................. 148–01–6 ............. ................ 5 ................ ................ ................ ................ ................

Dinitrobenzene (all isomers) .............................................. (alpha): 528–29–0 

(meta): 99–65–0. 

(para-): 100–25–4. 

................ 1 ................ ................ ................ ................ X 

Dinitro-o-cresol ................................................................... 534–52–1 ............. ................ 0.2 ................ ................ ................ ................ X 

Dinitrotoluene ..................................................................... 121–14–2 ............. ................ 1.5 ................ ................ ................ ................ X 

Dioxane (Diethylene dioxide) ............................................. 123–91–1 ............. 25 90 ................ ................ ................ ................ X 

Dioxathion (Delnav) ............................................................ 78–34–2 ............... ................ 0.2 ................ ................ ................ ................ X 

Diphenyl (Biphenyl) ............................................................ 92–52–4 ............... 0.2 1 ................ ................ ................ ................ ................

Diphenylamine .................................................................... 122–39–4 ............. ................ 10 ................ ................ ................ ................ ................

Diphenylmethane diisocyanate; see Methylene bisphenyl 

isocyanate.

101–68–8. 

Dipropylene glycol methyl ether ......................................... 34590–94–8 ......... 100 600 150 900 ................ ................ X 

Dipropyl ketone .................................................................. 123–19–3 ............. 50 235 ................ ................ ................ ................ ................

Diquat ................................................................................. 85–00–7 ............... ................ 0.5 ................ ................ ................ ................ ................

Di-sec octyl phthalate (Di-2-ethylhexyl phthalate) ............. 117–81–7 ............. ................ 5 ................ 10 ................ ................ ................

Disulfiram ............................................................................ 97–77–8 ............... ................ 2 ................ ................ ................ ................ ................

Disulfoton ............................................................................ 298–04–4 ............. ................ 0.1 ................ ................ ................ ................ X 

2,6-Di-tert-butyl-p-cresol ..................................................... 128–37–0 ............. ................ 10 ................ ................ ................ ................ ................

Diuron ................................................................................. 330–54–1 ............. ................ 10 ................ ................ ................ ................ ................

Divinyl benzene .................................................................. 108–576 ............... 10 50 ................ ................ ................ ................ ................

Emery ................................................................................. 112–62–9. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Endosulfan .......................................................................... 115–29–7 ............. ................ 0.1 ................ ................ ................ ................ X 

Endrin ................................................................................. 72–20–8 ............... ................ 0.1 ................ ................ ................ ................ X 

Epichlorohydrin ................................................................... 106–89–8 ............. 2 8 ................ ................ ................ ................ X 

EPN .................................................................................... 2104–64–5 ........... ................ 0.5 ................ ................ ................ ................ X 

1,2-Epoxypropane; see Propylene oxide ........................... 75–56–9. 

2,3-Epoxy-l-propanol; see Glycidol .................................... 556–52–5. 

Ethanethiol; see Ethyl mercaptan ...................................... 75–08–1. 

Ethanolamine ...................................................................... 141–43–5 ............. 3 8 6 15 ................ ................ ................

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 61429 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Ethion ................................................................................. 563–12–2 ............. ................ 0.4 ................ ................ ................ ................ X 

2-Ethoxyethanol [In Process of 6(b) Rulemaking] ............. 110–80–5. 

2-Ethoxyethyl acetate (Cellosolve acetate) [In Process of 

6(b) Rulemaking].

111–15–9. 

Ethyl acetate ....................................................................... 141–78–6 ............. 400 1400 ................ ................ ................ ................ ................

Ethyl acrylate ...................................................................... 140–88–5 ............. 5 20 25 100 ................ ................ X 

Ethyl alcohol (Ethanol) ....................................................... 64–17–5 ............... 1000 1900 ................ ................ ................ ................ ................

Ethylamine .......................................................................... 75–04–7 ............... 10 18 ................ ................ ................ ................ ................

Ethyl amyl ketone (5-Methyl-3-heptanone) ........................ 106–68–3 ............. 25 130 ................ ................ ................ ................ ................

Ethyl benzene ..................................................................... 100–41–4 ............. 100 435 125 545 ................ ................ ................

Ethyl bromide ..................................................................... 74–96–4 ............... 200 890 250 1110 ................ ................ ................

Ethyl butyl ketone (3-Heptanone) ...................................... 106–35–4 ............. 50 230 ................ ................ ................ ................ ................

Ethyl chloride ...................................................................... 75–00–3 ............... 1000 2600 ................ ................ ................ ................ ................

Ethyl ether .......................................................................... 60–29–7 ............... 400 1200 500 1500 ................ ................ ................

Ethyl formate ...................................................................... 109–94–4 ............. 100 300 ................ ................ ................ ................ ................

Ethyl mercaptan ................................................................. 75–08–1 ............... 0.5 1 ................ ................ ................ ................ ................

Ethyl silicate ....................................................................... 78–10–4 ............... 10 85 ................ ................ ................ ................ ................

Ethylene chlorohydrin ......................................................... 107–07–3 ............. ................ ................ ................ ................ 1 3 X 

Ethylenediamine ................................................................. 107–15–3 ............. 10 25 ................ ................ ................ ................ ................

Ethylene dibromide; see Table Z–2 ................................... 106–93–4. 

Ethylene dichloride ............................................................. 107–06–2 ............. 1 4 2 8 ................ ................ ................

Ethylene glycol ................................................................... 107–21–1 ............. ................ ................ ................ ................ 50 125 ................

Ethylene glycol dinitrate ..................................................... 628–96–6 ............. ................ ................ ................ 0.1 ................ ................ X 

Ethylene glycol methyl acetate; see Methyl cellosolve acetate.110–49–6. 

Ethyleneimine; see 1910.1012 ........................................... 151–56–4. 

Ethylene oxide; see 1910.1047 .......................................... 75–21–8. 

Ethylidene chloride; see 1,1-Dichloroethane ..................... 75–34–3. 

Ethylidene norbornene ....................................................... 16219–75–3 ......... ................ ................ ................ ................ 5 25 ................

N-Ethylmorpholine .............................................................. 100–74–3 ............. 5 23 ................ ................ ................ ................ X 

Fenamiphos ........................................................................ 22224–92–6 ......... ................ 0.1 ................ ................ ................ ................ X 

Fensulfothion (Dasanit) ...................................................... 115–90–2 ............. ................ 0.1 ................ ................ ................ ................ ................

Fenthion .............................................................................. 55–38–9 ............... ................ 0.2 ................ ................ ................ ................ X 

Ferbam ............................................................................... 14484–64–1. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Ferrovanadium dust ........................................................... 12604–58–9 ......... ................ 1 ................ 3 ................ ................ ................

Fluorides (as F) .................................................................. Varies with compound................. 2.5 ................ ................ ................ ................ ................

Fluorine ............................................................................... 7782–41–4 ........... 0.1 0.2 ................ ................ ................ ................ ................

Fluoro-trichloromethane (Trichlorofluoro-methane) ............ 75–69–4 ............... ................ ................ ................ ................ 1000 5600 ................

Fonofos ............................................................................... 944–22–9 ............. ................ 0.1 ................ ................ ................ ................ X 

Formaldehyde; see 1910.1048 .......................................... 50–00–0. 

Formamide ......................................................................... 75–12–7 ............... 20 30 30 45 ................ ................ ................

Formic acid ......................................................................... 64–18–6 ............... 5 9 ................ ................ ................ ................ ................

Furfural ............................................................................... 98–01–1 ............... 2 8 ................ ................ ................ ................ X 

Furfuryl alcohol ................................................................... 98–00–0 ............... 10 40 15 60 ................ ................ X 

Gasoline ............................................................................. 8006–61–9 ........... 300 900 500 1500 ................ ................ ................

Gemanium tetrahydride ...................................................... 7782–65–2 ........... 0.2 0.6 ................ ................ ................ ................ ................

Glutaraldehyde ................................................................... 111–30–8 ............. ................ ................ ................ ................ 0.2 0.8 ................

Glycerin (mist) .................................................................... 56–81–5. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Glycidol ............................................................................... 556–52–5 ............. 25 75 ................ ................ ................ ................ ................

Glycol monoethyl ether; see 2-Ethoxyethanol ................... 110–80–5. 

Grain dust (oat, wheat, barley) .......................................... N/A ....................... ................ 10 ................ ................ ................ ................ ................

Graphite, natural respirable dust ........................................ 7782–42–5 ........... ................ 2.5 ................ ................ ................ ................ ................

Graphite, synthetic ............................................................. N/A. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Guthion®; see Azinphos methyl ......................................... 86–50–0. 

Gypsum .............................................................................. 7778–18–9. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Hafnium .............................................................................. 7440–58–6 ........... ................ 0.5 ................ ................ ................ ................ ................

Heptachlor .......................................................................... 76–44–8 ............... ................ 0.5 ................ ................ ................ ................ X 

Heptane (n-Heptane) .......................................................... 142–82–5 ............. 400 1600 500 2000 ................ ................ ................

Hexachloro-butadiene ........................................................ 87–68–3 ............... 0.02 0.24 ................ ................ ................ ................ ................

Hexachlorocyclo-pentadiene .............................................. 77–47–4 ............... 0.01 0.1 ................ ................ ................ ................ ................

Hexa-chloroethane ............................................................. 67–72–1 ............... 1 10 ................ ................ ................ ................ X 

Hexachloro-naphthalene .................................................... 1335–87–1 ........... ................ 0.2 ................ ................ ................ ................ X 

Hexafluoro-acetone ............................................................ 684–16–2 ............. 0.1 0.7 ................ ................ ................ ................ X 

n-Hexane ............................................................................ 110–54–3 ............. 50 180 ................ ................ ................ ................ ................

Hexane isomers ................................................................. Varies with compound.500 1800 1000 3600 ................ ................ ................

2-Hexanone (Methyl n-butyl ketone) .................................. 591–78–6 ............. 5 20 ................ ................ ................ ................ ................

Hexone (Methyl isobutyl ketone) ........................................ 108–10–1 ............. 50 205 75 300 ................ ................ ................

sec-Hexyl acetate ............................................................... 108–84–9 ............. 50 300 ................ ................ ................ ................ ................

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

61430 Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Hexylene glycol .................................................................. 107–41–5 ............. ................ ................ ................ ................ 25 125 ................

Hydrazine ........................................................................... 302–01–2 ............. 0.1 0.1 ................ ................ ................ ................ X 

Hydrogenated terphenyls ................................................... 61788–32–7 ......... 0.5 5 ................ ................ ................ ................ ................

Hydrogen bromide .............................................................. 10035–10–6 ......... ................ ................ ................ ................ 3 10 ................

Hydrogen chloride .............................................................. 7647–01–0 ........... ................ ................ ................ ................ 5 7 ................

Hydrogen cyanide .............................................................. 74–90–8 ............... ................ ................ 4.7 5 ................ ................ X 

Hydrogen fluoride (as F) .................................................... 7664–39–3 ........... 3 ................ 6 ................ ................ ................ ................

Hydrogen peroxide ............................................................. 7722–84–1 ........... 1 1.4 ................ ................ ................ ................ ................

Hydrogen selenide (as Se) ................................................ 7783–07–5 ........... 0.05 0.2 ................ ................ ................ ................ ................

Hydrogen sulfide ................................................................ 7783–06–4 ........... 10 14 15 21 ................ ................ ................

Hydroquinone ..................................................................... 123–31–9 ............. ................ 2 ................ ................ ................ ................ ................

2-Hydroxypropyl acrylate .................................................... 999–61–1 ............. 0.5 3 ................ ................ ................ ................ X 

Indene ................................................................................. 95–13–6 ............... 10 45 ................ ................ ................ ................ ................

Indium and compounds (as In) .......................................... 7440–74–6 ........... ................ 0.1 ................ ................ ................ ................ ................

Iodine .................................................................................. 7553–56–2 ........... ................ ................ ................ ................ 0.1 1 ................

Iodoform ............................................................................. 75–47–8 ............... 0.6 10 ................ ................ ................ ................ ................

Iron oxide (dust and fume as Fe) Total particulate ........... 1309–37–1 ........... ................ 10 ................ ................ ................ ................ ................

Iron pentacarbonyl (as Fe) ................................................. 13463–40–6 ......... 0.1 0.8 0.2 1.6 ................ ................ ................

Iron salts (soluble) (as Fe) ................................................. Varies with compound................. 1 ................ ................ ................ ................ ................

Isoamyl acetate .................................................................. 123–92–2 ............. 100 525 ................ ................ ................ ................ ................

Isoamyl alcohol (primary and secondary) .......................... 123–51–3 ............. 100 360 125 450 ................ ................ ................

Isobutyl acetate .................................................................. 110–19–0 ............. 150 700 ................ ................ ................ ................ ................

Isobutyl alcohol ................................................................... 78–83–1 ............... 50 150 ................ ................ ................ ................ ................

Isooctyl alcohol ................................................................... 26952–21–6 ......... 50 270 ................ ................ ................ ................ X 

Isophorone .......................................................................... 78–59–1 ............... 4 23 ................ ................ ................ ................ ................

Isophorone diisocyanate .................................................... 4098–71–9 ........... 0.005 ................ 0.02 ................ ................ ................ X 

2-Isopropoxy-ethanol .......................................................... 109–59–1 ............. 25 105 ................ ................ ................ ................ ................

Isopropyl acetate ................................................................ 108–21–4 ............. 250 950 310 1185 ................ ................ ................

Isopropyl alcohol ................................................................ 67–63–0 ............... 400 980 500 1225 ................ ................ ................

Isopropylamine ................................................................... 75–31–0 ............... 5 12 10 24 ................ ................ ................

N-Isopropylaniline ............................................................... 768–52–5 ............. 2 10 ................ ................ ................ ................ X 

Isopropyl ether .................................................................... 108–20–3 ............. 500 2100 ................ ................ ................ ................ ................

Isopropyl glycidyl ether (IGE) ............................................. 4016–14–2 ........... 50 240 75 360 ................ ................ ................

Kaolin .................................................................................. N/A. ................ ................ ................ ................ ................ ................ ................

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Ketene ................................................................................ 463–51–4 ............. 0.5 0.9 1.5 3 ................ ................ ................

Lead inorganic (as Pb); see 1910.1025 ............................. 7439–92–1. 

Limestone ........................................................................... 1317–65–3. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Lindane ............................................................................... 58–89–9 ............... ................ 0.5 ................ ................ ................ ................ X 

Lithium hydride ................................................................... 7580–67–8 ........... ................ 0.025 ................ ................ ................ ................ ................

L.P.G. (Liquefied petroleum gas) ....................................... 68476–85–7 ......... 1000 1800 ................ ................ ................ ................ ................

Magnesite ........................................................................... 546–93–0. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Magnesium oxide fume, total particulate ........................... 1309–48–4. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Malathion ............................................................................ 121–75–5. 

Total dust ............. ................ 10 ................ ................ ................ ................ X 

Respirable fraction ................ 5 ................ ................ ................ ................ X 

Maleic anhydride ................................................................ 108–31–6 ............. 0.25 1 ................ ................ ................ ................ ................

Manganese compounds (as Mn) ....................................... 7439–96–5 ........... ................ ................ ................ ................ ................ 5 ................

Manganese fume (as Mn) .................................................. 7439–96–5 ........... ................ 1 ................ 3 ................ ................ ................

Manganese cyclopentadienyl tricarbonyl (as Mn) .............. 12079–65–1 ......... ................ 0.1 ................ ................ ................ ................ X 

Manganese tetroxide (as Mn) ............................................ 1317–35–7 ........... ................ 1 ................ ................ ................ ................ ................

Marble ................................................................................. 1317–65–3. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Mercury (aryl and inorganic) (as Hg) ................................. 7439–97–6 ........... ................ ................ ................ ................ ................ 0.1 X 

Mercury (organo) alkyl compounds (as Hg) ...................... 7439–97–6 ........... ................ 0.01 ................ 0.03 ................ ................ X 

Mercury (vapor) (as Hg) ..................................................... 7439–97–6 ........... ................ 0.05 ................ ................ ................ ................ X 

Mesityl oxide ....................................................................... 141–79–7 ............. 15 60 25 100 ................ ................ ................

Methacrylic acid .................................................................. 79–41–4 ............... 20 70 ................ ................ ................ ................ X 

Methanethiol; see Methyl mercaptan ................................. 74–93–1. 

Methomyl (Lannate) ........................................................... 16752–77–5 ......... ................ 2.5 ................ ................ ................ ................ ................

Methoxychlor ...................................................................... 72–43–5. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

2-Methoxyethanol; see Methyl cellosolve .......................... 109–86–4. 

4-Methoxyphenol ................................................................ 150–76–5 ............. ................ 5 ................ ................ ................ ................ ................

Methyl acetate .................................................................... 79–20–9 ............... 200 610 250 760 ................ ................ ................

Methyl acetylene (Propyne) ............................................... 74–99–7 ............... 1000 1650 ................ ................ ................ ................ ................

Methyl acetylene-propadiene mixture (MAPP) .................. ............................... 1000 1800 1250 2250 ................ ................ ................

Methyl acrylate ................................................................... 96–33–3 ............... 10 35 ................ ................ ................ ................ X 

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 61431 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Methyl-acrylonitrile .............................................................. 126–98–7 ............. 1 3 ................ ................ ................ ................ X 

Methylal (Dimethoxy-methane) .......................................... 109–87–5 ............. 1000 3100 ................ ................ ................ ................ ................

Methyl alcohol .................................................................... 67–56–1 ............... 200 260 250 325 ................ ................ X 

Methylamine ....................................................................... 74–89–5 ............... 10 12 ................ ................ ................ ................ ................

Methyl amyl alcohol; see Methyl isobutyl carbinol ............. 108–11–2. 

Methyl n-amyl ketone ......................................................... 110–43–0 ............. 100 465 ................ ................ ................ ................ ................

Methyl bromide ................................................................... 74–83–9 ............... 5 20 ................ ................ ................ ................ X 

Methyl butyl ketone; see 2-Hexanone ............................... 591–78–6. 

Methyl cellosolve (2-Methoxyethanol) ................................ 109–86–4 ............. 25 80 ................ ................ ................ ................ X 

Methyl cellosolve acetate (2-Methoxyethyl acetate) .......... 110–49–6 ............. 25 120 ................ ................ ................ ................ X 

Methyl chloride ................................................................... 74–87–3 ............... 50 105 100 210 ................ ................ ................

Methyl chloroform (1,1,1-Trichloroethane) ......................... 71–55–6 ............... 350 1900 450 2450 ................ ................ ................

Methyl 2-cyanoacrylate ...................................................... 137–05–3 ............. 2 8 4 16 ................ ................ ................

Methyl cyclohexane ............................................................ 108–87–2 ............. 400 1600 ................ ................ ................ ................ ................

Methyl-cyclohexanol ........................................................... 25639–42–3 ......... 50 235 ................ ................ ................ ................ ................

o-Methylcyclo-hexanone ..................................................... 583–60–8 ............. 50 230 75 345 ................ ................ X 

Methylcyclo-pentadienyl manganese tricarbonyl (as Mn) .. 12108–13–3 ......... ................ 0.2 ................ ................ ................ ................ X 

Methyl demeton .................................................................. 8022–00–2 ........... ................ 0.5 ................ ................ ................ ................ X 

4,4′-Methylene bis(2-chloroaniline) (MBOCA) .................... 101–14–4 ............. 0.02 0.22 ................ ................ ................ ................ X 

Methylene bis(4-cyclo-hexylisocyanate) ............................. 5124–30–1 ........... ................ ................ ................ ................ 0.01 0.11 X 

Methylene chloride; see 1910.1052 ................................... 75–09–2. 

Methylene-dianiline; see 1910.1050 .................................. 101–77–9. 

Methyl ethyl ketone peroxide (MEKP) ............................... 1338–23–4 ........... ................ ................ ................ ................ 0.7 5 ................

Methyl formate .................................................................... 107–31–3 ............. 100 250 150 375 ................ ................ ................

Methyl hydrazine (Monomethyl hydrazine) ........................ 60–34–4 ............... ................ ................ ................ ................ 0.2 0.35 X 

Methyl iodide ...................................................................... 74–88–4 ............... 2 10 ................ ................ ................ ................ X 

Methyl isoamyl ketone ........................................................ 110–12–3 ............. 50 240 ................ ................ ................ ................ ................

Methyl isobutyl carbinol ...................................................... 108–11–2 ............. 25 100 40 165 ................ ................ X 

Methyl isobutyl ketone; see Hexone .................................. 108–10–1. 

Methyl isocyanate ............................................................... 624–83–9 ............. 0.02 0.05 ................ ................ ................ ................ X 

Methyl isopropyl ketone ..................................................... 563–80–4 ............. 200 705 ................ ................ ................ ................ ................

Methyl mercaptan ............................................................... 74–93–1 ............... 0.5 1 ................ ................ ................ ................ ................

Methyl methacrylate ........................................................... 80–62–6 ............... 100 410 ................ ................ ................ ................ ................

Methyl parathion ................................................................. 298–00–0 ............. ................ 0.2 ................ ................ ................ ................ X 

Methyl propyl ketone; see 2-Pentanone ............................ 107–87–9. 

Methyl silicate ..................................................................... 681–84–5 ............. 1 6 ................ ................ ................ ................ ................

alpha-Methyl styrene .......................................................... 98–83–9 ............... 50 240 100 485 ................ ................ ................

Methylene bisphenyl isocyanate (MDI) .............................. 101–68–8 ............. ................ ................ ................ ................ 0.02 0.2 ................

Metribuzin ........................................................................... 21087–64–9 ......... ................ 5 ................ ................ ................ ................ ................

Mica; see Silicates ............................................................. N/A. 

Molybdenum (as Mo) ......................................................... 7439–98–7. 

Soluble compounds................. 5 ................ ................ ................ ................ ................

Insoluble compounds total 

dust.

................ 10 ................ ................ ................ ................ ................

Insoluble compounds.

Respirable fraction 

................ 5 ................ ................ ................ ................ ................

Monocrotophos (Azodrin) ................................................... 6923–22–4 ........... ................ 0.25 ................ ................ ................ ................ ................

Monomethyl aniline ............................................................ 100–61–8 ............. 0.5 2 ................ ................ ................ ................ X 

Morpholine .......................................................................... 110–91–8 ............. 20 70 30 105 ................ ................ X 

Naphtha (Coal tar) .............................................................. 8030–30–6 ........... 100 400 ................ ................ ................ ................ ................

Naphthalene ....................................................................... 91–20–3 ............... 10 50 15 75 ................ ................ ................

alpha-Naphthylamine; see 1910.1004 ............................... 134–32–7. 

beta-Naphthylamine; see 1910.1009 ................................. 91–59–8. 

Nickel carbonyl (as Ni) ....................................................... 13463–39–3 ......... 0.001 0.007 ................ ................ ................ ................ ................

Nickel, metal and insoluble compounds (as Ni) ................ 7440–02–0 ........... ................ 1 ................ ................ ................ ................ ................

Nickel, soluble compounds (as Ni) .................................... 7440–02–0 ........... ................ 0.1 ................ ................ ................ ................ ................

Nicotine ............................................................................... 54–11–5 ............... ................ 0.5 ................ ................ ................ ................ X 

Nitric acid ............................................................................ 7697–37–2 ........... 2 5 4 10 ................ ................ ................

Nitric oxide .......................................................................... 10102–43–9 ......... 25 30 ................ ................ ................ ................ ................

p-Nitroaniline ...................................................................... 100–01–6 ............. ................ 3 ................ ................ ................ ................ X 

Nitrobenzene ...................................................................... 98–95–3 ............... 1 5 ................ ................ ................ ................ X 

p-Nitrochloro-benzene ........................................................ 100–00–5 ............. ................ 1 ................ ................ ................ ................ X 

4-Nitrodiphenyl; see 1910.1003 ......................................... 92–93–3. 

Nitroethane ......................................................................... 79–24–3 ............... 100 310 ................ ................ ................ ................ ................

Nitrogen dioxide ................................................................. 10102–44–0 ......... ................ ................ 1 1.8 ................ ................ ................

Nitrogen trifluoride .............................................................. 7783–54–2 ........... 10 29 ................ ................ ................ ................ ................

Nitroglycerin ........................................................................ 55–63–0 ............... ................ ................ ................ 0.11 ................ ................ X 

Nitromethane ...................................................................... 75–52–5 ............... 100 250 ................ ................ ................ ................ ................

1-Nitropropane .................................................................... 108–03–2 ............. 25 90 ................ ................ ................ ................ ................

2-Nitropropane .................................................................... 79–46–9 ............... 10 35 ................ ................ ................ ................ ................

N-Nitrosodimethyl-amine; see 1910.1016 .......................... 62–75–9. 

Nitrotoluene ........................................................................ o-isomer 88–72–2 

m-isomer 99–08–1 

p-isomer 99–99–0. 

2 11 ................ ................ ................ ................ X 

Nitrotrichloro-methane; see Chloropicrin ............................ 76–06–2. 

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

61432 Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Nonane ............................................................................... 111–84–2 ............. 200 1050 ................ ................ ................ ................ ................

Octachloro-naphthalene ..................................................... 2234–13–1 ........... ................ 0.1 ................ 0.3 ................ ................ X 

Octane ................................................................................ 111–65–9 ............. 300 1450 375 1800 ................ ................ ................

Oil mist, mineral ................................................................. 8012–95–1 ........... ................ 5 ................ ................ ................ ................ ................

Osmium tetroxide (as Os) .................................................. 20816–12–0 ......... 0.0002 0.002 0.0006 0.006 ................ ................ ................

Oxalic acid .......................................................................... 144–62–7 ............. ................ 1 ................ 2 ................ ................ ................

Oxygen difluoride ............................................................... 7783–41–7 ........... ................ ................ ................ ................ 0.05 0.1 ................

Ozone ................................................................................. 10028–15–6 ......... 0.1 0.2 0.3 0.6 ................ ................ ................

Paraffin wax fume .............................................................. 8002–74–2 ........... ................ 2 ................ ................ ................ ................ ................

Paraquat, respirable dust ................................................... 4685–14–7 ........... ................ 0.1 ................ ................ ................ ................ X 

Parathion ............................................................................ 56–38–2 ............... ................ 0.1 ................ ................ ................ ................ X 

Particulates not otherwise regulated .................................. N/A. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Pentaborane ....................................................................... 19624–22–7 ......... 0.005 0.01 0.015 0.03 ................ ................ ................

Pentachloro-naphthalene ................................................... 1321–64–8 ........... ................ 0.5 ................ ................ ................ ................ X 

Pentachloro-phenol ............................................................ 87–86–5 ............... ................ 0.5 ................ ................ ................ ................ X 

Pentaerythritol .................................................................... 115–77–5. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Pentane .............................................................................. 109–66–0 ............. 600 1800 750 2250 ................ ................ ................

2-Pentanone (Methyl propyl ketone) .................................. 107–87–9 ............. 200 700 250 875 ................ ................ ................

Perchloro-ethylene (Tetrachloro-ethylene) ......................... 127–18–4 ............. 25 170 ................ ................ ................ ................ ................

Perchloromethyl mercaptan ............................................... 594–42–3 ............. 0.1 0.8 ................ ................ ................ ................ ................

Perchloryl fluoride ............................................................... 7616–94–6 ........... 3 14 6 28 ................ ................ ................

Perlite. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Petroleum distillates (Naphtha) .......................................... 8002–05–9 ........... 400 1600 ................ ................ ................ ................ ................

Phenol ................................................................................ 108–95–2 ............. 5 19 ................ ................ ................ ................ X 

Phenothiazine ..................................................................... 92–84–2 ............... ................ 5 ................ ................ ................ ................ X 

p-Phenylene diamine .......................................................... 106–50–3 ............. ................ 0.1 ................ ................ ................ ................ X 

Phenyl ether, vapor ............................................................ 101–84–8 ............. 1 7 ................ ................ ................ ................ ................

Phenyl ether-biphenyl mixture, vapor ................................ N/A ....................... 1 7 ................ ................ ................ ................ ................

Phenylethylene; see Styrene ............................................. 100–42–5. 

Phenyl glycidyl ether (PGE) ............................................... 122–60–1 ............. 1 6 ................ ................ ................ ................ ................

Phenylhydrazine ................................................................. 100–63–0 ............. 5 20 10 45 ................ ................ X 

Phenyl mercaptan .............................................................. 108–98–5 ............. 0.5 2 ................ ................ ................ ................ ................

Phenylphosphine ................................................................ 638–21–1 ............. ................ ................ ................ ................ 0.05 0.25 ................

Phorate ............................................................................... 298–02–2 ............. ................ 0.05 ................ 0.2 ................ ................ X 

Phosdrin (Mevinphos®) ...................................................... 7786–34–7 ........... 0.01 0.1 0.03 0.3 ................ ................ X 

Phosgene (Carbonyl chloride) ............................................ 75–44–5 ............... 0.1 0.4 ................ ................ ................ ................ ................

Phosphine ........................................................................... 7803–51–2 ........... 0.3 0.4 1 1 ................ ................ ................

Phosphoric acid .................................................................. 7664–38–2 ........... ................ 1 ................ 3 ................ ................ ................

Phosphorus (yellow) ........................................................... 7723–14–0 ........... ................ 0.1 ................ ................ ................ ................ ................

Phosphorus oxychloride ..................................................... 10025–87–3 ......... 0.1 0.6 ................ ................ ................ ................ ................

Phosphorus pentachloride .................................................. 10026–13–8 ......... ................ 1 ................ ................ ................ ................ ................

Phosphorus pentasulfide .................................................... 1314–80–3 ........... ................ 1 ................ 3 ................ ................ ................

Phosphorus trichloride ........................................................ 7719–12–2 ........... 0.2 1.5 0.5 3 ................ ................ ................

Phthalic anhydride .............................................................. 85–44–9 ............... 1 6 ................ ................ ................ ................ ................

m-Phthalodinitrile ................................................................ 626–17–5 ............. ................ 5 ................ ................ ................ ................ ................

Picloram .............................................................................. 1918–02–1. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Picric acid ........................................................................... 88–89–1 ............... ................ 0.1 ................ ................ ................ ................ X 

Piperazine dihydrochloride ................................................. 142–64–3 ............. ................ 5 ................ ................ ................ ................ ................

Pindone (2-Pivalyl- 1,3-indandione) ................................... 83–26–1 ............... ................ 0.1 ................ ................ ................ ................ ................

Plaster of Paris ................................................................... 7778–18–9. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Platinum (as Pt) .................................................................. 7440–06–4. 

Metal ..................... ................ 1 ................ ................ ................ ................ ................

Soluble salts ......... ................ 0.002 ................ ................ ................ ................ ................

Portland cement ................................................................. 65997–15–1. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Potassium hydroxide .......................................................... 1310–58–3 ........... ................ ................ ................ ................ ................ 2 ................

Propane .............................................................................. 74–98–6 ............... 1000 1800 ................ ................ ................ ................ ................

Propargyl alcohol ................................................................ 107–19–7 ............. 1 2 ................ ................ ................ ................ X 

beta-Propriolactone; see 1910.1013 .................................. 57–57–8. 

Propionic acid ..................................................................... 79–09–4 ............... 10 30 ................ ................ ................ ................ ................

Propoxur (Baygon) ............................................................. 114–26–1 ............. ................ 0.5 ................ ................ ................ ................ ................

n-Propyl acetate ................................................................. 109–60–4 ............. 200 840 250 1050 ................ ................ ................

n-Propyl alcohol .................................................................. 71–23–8 ............... 200 500 250 625 ................ ................ ................

n-Propyl nitrate ................................................................... 627–13–4 ............. 25 105 40 170 ................ ................ ................

Propylene dichloride ........................................................... 78–87–5 ............... 75 350 110 510 ................ ................ ................

Propylene glycol dinitrate ................................................... 6423–43–4 ........... 0.05 0.3 ................ ................ ................ ................ ................

Propylene glycol monomethyl ether ................................... 107–98–2 ............. 100 360 150 540 ................ ................ ................

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 61433 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Propylene imine .................................................................. 75–55–8 ............... 2 5 ................ ................ ................ ................ X 

Propylene oxide .................................................................. 75–56–9 ............... 20 50 ................ ................ ................ ................ ................

Propyne; see Methyl acetylene .......................................... 74–99–7. 

Pyrethrum ........................................................................... 8003–34–7 ........... ................ 5 ................ ................ ................ ................ ................

Pyridine ............................................................................... 110–86–1 ............. 5 15 ................ ................ ................ ................ ................

Quinone .............................................................................. 106–51–4 ............. 0.1 0.4 ................ ................ ................ ................ ................

Resorcinol ........................................................................... 108–46–3 ............. 10 45 20 90 ................ ................ ................

Rhodium (as Rh), metal fume and insoluble compounds 7440–16–6 ........... ................ 0.1 ................ ................ ................ ................ ................

Rhodium (as Rh), soluble compounds ............................... 7440–16–6 ........... ................ 0.001 ................ ................ ................ ................ ................

Ronnel ................................................................................ 299–84–3 ............. ................ 10 ................ ................ ................ ................ ................

Rosin core solder pyrolysis products, as formaldehyde .... ............................... ................ 0.1 ................ ................ ................ ................ ................

Rotenone ............................................................................ 83–79–4 ............... ................ 5 ................ ................ ................ ................ ................

Rouge. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Selenium compounds (as Se) ............................................ 7782–49–2 ........... ................ 0.2 ................ ................ ................ ................ ................

Selenium hexafluoride (as Se) ........................................... 7783–79–1 ........... 0.05 0.4 ................ ................ ................ ................ ................

Silica, amorphous, precipitated and gel ............................. ............................... ................ 6 ................ ................ ................ ................ ................

Silica, amorphous, diatomaceous earth, containing less 

than 1% crystalline silica.

68855–54–9 ......... ................ 6 ................ ................ ................ ................ ................

Silica, crystalline cristobalite respirable dust ..................... 14464–46–1 ......... ................ 0.05 ................ ................ ................ ................ ................

Silica, crystalline, quartz, respirable dust ........................... 14808–60–7 ......... ................ 0.1 ................ ................ ................ ................ ................

Silica, crystalline tripoli (as quartz), respirable dust .......... 1317–95–9 ........... ................ 0.1 ................ ................ ................ ................ ................

Silica, crystalline tridymite respirable dust ......................... 15468–32–3 ......... ................ 0.05 ................ ................ ................ ................ ................

Silica, fused, respirable dust .............................................. 60676–86–0 ......... ................ 0.1 ................ ................ ................ ................ ................

Silicates (less than 1% crystalline silica) 

Mica (respirable dust) ......................................................... 12001–26–2 ......... ................ 3 ................ ................ ................ ................ ................

Soapstone, total dust ......................................................... ............................... ................ 6 ................ ................ ................ ................ ................

Soapstone, respirable dust ................................................ ............................... ................ 3 ................ ................ ................ ................ ................

Talc (containing asbestos): Use asbestos limit; see 

1910.1001. 

Talc (containing no asbestos), respirable dust .................. 14807–96–6 ......... ................ 2 ................ ................ ................ ................ ................

Tremolite; asbestiform—see 1910.1001; nonasbestiform—see 57 FR 24310, June 8, 1992................................ ................ ................ ................ ................ ................ ................ ................

Silicon ................................................................................. 7440–21–3. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Silicon carbide .................................................................... 409–21–2. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Silicon tetrahydride ............................................................. 7803–62–5 ........... 5 7 ................ ................ ................ ................ ................

Silver, metal and soluble compounds (as Ag) ................... 7440–22–4 ........... ................ 0.01 ................ ................ ................ ................ ................

Soapstone; see Silicates 

Sodium azide ...................................................................... 26628–22–8. 

(as HN3) ............... ................ ................ ................ ................ 0.1 ................ X 

(as NaN3 ) ............ ................ ................ ................ ................ ................ 0.3 X 

Sodium bisulfite .................................................................. 7631–90–5 ........... ................ 5 ................ ................ ................ ................ ................

Sodium fluoroacetate ......................................................... 62–74–8 ............... ................ 0.05 ................ 0.15 ................ ................ X 

Sodium hydroxide ............................................................... 1310–73–2 ........... ................ ................ ................ ................ ................ 2 ................

Sodium metabisulfite .......................................................... 7681–57–4 ........... ................ 5 ................ ................ ................ ................ ................

Starch ................................................................................. 9005–25–8. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Stibine ................................................................................. 7803–52–3 ........... 0.1 0.5 ................ ................ ................ ................ ................

Stoddard solvent ................................................................ 8052–41–3 ........... 100 525 ................ ................ ................ ................ ................

Strychnine ........................................................................... 57–24–9 ............... ................ 0.15 ................ ................ ................ ................ ................

Styrene ............................................................................... 100–42–5 ............. 50 215 100 425 ................ ................ ................

Subtilisins (Proteolytic enzymes) ....................................... 1395–21–7 ........... ................ ................ ................ ................ ................ 0. 00006 ................

Sucrose .............................................................................. 57–50–1. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Sulfur dioxide ...................................................................... 7446–09–5 ........... 2 5 5 13 ................ ................ ................

Sulfur hexafluoride ............................................................. 2551–62–4 ........... 1000 6000 ................ ................ ................ ................ ................

Sulfuric acid ........................................................................ 7664–93–9 ........... ................ 1 ................ ................ ................ ................ ................

Sulfur monochloride ........................................................... 10025–67–9 ......... ................ ................ ................ ................ 1 6 ................

Sulfur pentafluoride ............................................................ 5714–22–7 ........... ................ ................ ................ ................ 0.01 0.1 ................

Sulfur tetrafluoride .............................................................. 7783–60–0 ........... ................ ................ ................ ................ 0.1 0.4 ................

Sulfuryl fluoride ................................................................... 2699–79–8 ........... 5 20 10 40 ................ ................ ................

Sulprofos ............................................................................ 35400–43–2 ......... ................ 1 ................ ................ ................ ................ ................

Systox®; see Demeton ....................................................... 8065–48–3. 

2,4,5–T ............................................................................... 93–76–5 ............... ................ 10 ................ ................ ................ ................ ................

Talc; see Silicates. 

Tantalum, metal and oxide dust ......................................... 7440–25–7 ........... ................ 5 ................ ................ ................ ................ ................

TEDP (Sulfotep) ................................................................. 3689–24–5 ........... ................ 0.2 ................ ................ ................ ................ X 

Tellurium and compounds (as Te) ..................................... 13494–80–9 ......... ................ 0.1 ................ ................ ................ ................ ................

Tellurium hexafluoride (as Te) ........................................... 7783–80–4 ........... 0.02 0.2 ................ ................ ................ ................ ................

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

61434 Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Temephos ........................................................................... 3383–96–8. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

TEPP .................................................................................. 107–49–3 ............. ................ 0.05 ................ ................ ................ ................ X 

Terphenyls .......................................................................... 26140–60–3 ......... ................ ................ ................ ................ 0.5 5 ................

1,1,1,2-Tetrachloro-2,2-difluoroethane ............................... 76–11–9 ............... 500 4170 ................ ................ ................ ................ ................

1,1,2,2-Tetrachloro 1,2-difluoroethane ............................... 76–12–0 ............... 500 4170 ................ ................ ................ ................ ................

1,1,2,2-Tetrachloro-ethane ................................................. 79–34–5 ............... 1 7 ................ ................ ................ ................ X 

Tetrachoro-ethylene; see Perchloro-ethylene .................... 127–18–4. 

Tetrachloro-methane; see Carbon tetrachloride ................ 56–23–5. 

Tetrachloro-naphthalene .................................................... 1335–88–2 ........... ................ 2 ................ ................ ................ ................ X 

Tetraethyl lead (as Pb) ....................................................... 78–00–2 ............... ................ 0.075 ................ ................ ................ ................ X 

Tetrahydrofuran .................................................................. 109–99–9 ............. 200 590 250 735 ................ ................ ................

Tetramethyl lead (as Pb) .................................................... 75–74–1 ............... ................ 0.075 ................ ................ ................ ................ X 

Tetramethyl succinonitrile ................................................... 3333–52–6 ........... 0.5 3 ................ ................ ................ ................ X 

Tetranitro-methane ............................................................. 509–14–8 ............. 1 8 ................ ................ ................ ................ ................

Tetrasodium pyrophosphate ............................................... 7722–88–5 ........... ................ 5 ................ ................ ................ ................ ................

Tetryl (2,4,6-Trinitro-phenyl-methyl-nitramine) ................... 479–45–8 ............. ................ 0.1 ................ ................ ................ ................ X 

Thallium, soluble compounds (as Tl) ................................. 7440–28–0 ........... ................ 0.1 ................ ................ ................ ................ X 

4,4′-Thiobis (6-tert-Butyl-m-cresol) ..................................... 96–69–5. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Thioglycolic acid ................................................................. 68–11–1 ............... 1 4 ................ ................ ................ ................ X 

Thionyl chloride .................................................................. 7719–09–7 ........... ................ ................ ................ ................ 1 5 ................

Thiram ................................................................................ 137–26–8 ............. ................ 5 ................ ................ ................ ................ ................

Tin, inorganic compounds (except oxides) (as Sn) ........... 7440–31–5 ........... ................ 2 ................ ................ ................ ................ ................

Tin, organic compounds (as Sn) ........................................ 7440–31–5 ........... ................ 0.1 ................ ................ ................ ................ X 

Tin oxide (as Sn) ................................................................ 7440–31–5 ........... ................ 2 ................ ................ ................ ................ ................

Titanium dioxide ................................................................. 13463–67–7. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Toluene ............................................................................... 108–88–3 ............. 100 375 150 560 ................ ................ ................

Toluene-2,4-diisocyanate (TDI) .......................................... 584–84–9 ............. 0.005 0.04 0.02 0.15 ................ ................ ................

m-Toluidine ......................................................................... 108–44–1 ............. 2 9 ................ ................ ................ ................ X 

o-Toluidine .......................................................................... 95–53–4 ............... 5 22 ................ ................ ................ ................ X 

p-Toluidine .......................................................................... 106–49–0 ............. 2 9 ................ ................ ................ ................ X 

Toxaphene; see Chlorinated camphene ............................ 8001–35–2. 

Tremolite; see Silicates ...................................................... N/A. 

Tributyl phosphate .............................................................. 126–73–8 ............. 0.2 2.5 ................ ................ ................ ................ ................

Trichloroacetic acid ............................................................ 76–03–9 ............... 1 7 ................ ................ ................ ................ ................

1,2,4-Trichloro-benzene ..................................................... 120–82–1 ............. ................ ................ ................ ................ 5 40 ................

1,1,1-Trichloroethane; see Methyl chloroform ................... 71–55–6. 

1,1,2-Trichloroethane ......................................................... 79–00–5 ............... 10 45 ................ ................ ................ ................ X 

Trichloro-ethylene ............................................................... 79–01–6 ............... 50 270 200 1080 ................ ................ ................

Trichloro-methane; see Chloroform ................................... 67–66–3. 

Trichloro-naphthalene ......................................................... 1321–65–9 ........... ................ 5 ................ ................ ................ ................ X 

1,2,3-Trichloropropane ....................................................... 96–18–4 ............... 10 60 ................ ................ ................ ................ ................

1,1,2-Trichloro-1,2,2-trifluoroethane ................................... 76–13–1 ............... 1000 7600 1250 9500 ................ ................ ................

Triethylamine ...................................................................... 121–44–8 ............. 10 40 15 60 ................ ................ ................

Trifluorobromo-methane ..................................................... 75–63–8 ............... 1000 6100 ................ ................ ................ ................ ................

Trimellitic anhydride ........................................................... 552–30–7 ............. 0.005 0.04 ................ ................ ................ ................ ................

Trimethylamine ................................................................... 75–50–3 ............... 10 24 15 36 ................ ................ ................

Trimethyl benzene .............................................................. 25551–13–7 ......... 25 125 ................ ................ ................ ................ ................

Trimethyl phosphite ............................................................ 121–45–9 ............. 2 10 ................ ................ ................ ................ ................

2,4,6-Trinitrophenyl; see Picric acid ................................... 88–89–1. 

2,4,6-Trinitrophenylmethyl nitramine; see Tetryl ................ 479–45–8. 

2,4,6-Trinitrotoluene (TNT) ................................................. 118–96–1 ............. ................ 0.5 ................ ................ ................ ................ X 

Triorthocresyl phosphate .................................................... 78–30–8 ............... ................ 0.1 ................ ................ ................ ................ X 

Triphenyl amine .................................................................. 603–34–9 ............. ................ 5 ................ ................ ................ ................ ................

Triphenyl phosphate ........................................................... 115–86–6 ............. ................ 3 ................ ................ ................ ................ ................

Tungsten (as W) ................................................................. 7440–33–7. 

Insoluble compounds................. 5 ................ 10 ................ ................ ................

Soluble compounds................. 1 ................ 3 ................ ................ ................

Turpentine .......................................................................... 8006–64–2 ........... 100 560 ................ ................ ................ ................ ................

Uranium (as U) ................................................................... 7440–61–1. 

Soluble compounds................. 0.05 ................ ................ ................ ................ ................

Insoluble compounds................. 0.2 ................ 0.6 ................ ................ ................

n-Valeraldehyde ................................................................. 110–62–3 ............. 50 175 ................ ................ ................ ................ ................

Vanadium ........................................................................... 1314–62–1. 

Respirable Dust as 

V205.

................ 0.05 ................ ................ ................ ................ ................

Fume (as V205) ... ................ 0.05 ................ ................ ................ ................ ................

Vegetable Oil Mist .............................................................. N/A. 

Total dust ............. ................ 15 ................ ................ ................ ................ ................

mstockstill on DSK4VPTVN1PROD with PROPOSALS2

Federal Register / Vol. 79, No. 197 / Friday, October 10, 2014 / Proposed Rules 61435 

TABLE Z–1–A—LIMITS FOR AIR CONTAMINANTS—Continued 

[From the vacated 1989 final rule—Ex. #149] 

Substance Cas No. 

TWA STEL Ceiling Skin 

Designappm mg/m tion 3 ppm mg/m3 ppm mg/m3

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Vinyl acetate ....................................................................... 108–05–4 ............. 10 30 20 60 ................ ................ ................

Vinyl benzene; see Styrene ............................................... 100–42–5. 

Vinyl bromide ...................................................................... 593–60–2 ............. 5 20 ................ ................ ................ ................ ................

Vinyl chloride; see 1910.1017 ............................................ 75–01–4. 

Vinyl cyanide; see Acrylonitrile .......................................... 107–13–1. 

Vinyl cyclohexene dioxide .................................................. 106–87–6 ............. 10 60 ................ ................ ................ ................ X 

Vinylidene chloride (1,1-Dichloro-ethylene) ....................... 75–35–4 ............... 1 4 ................ ................ ................ ................ ................

Vinyl toluene ....................................................................... 25013–15–4 ......... 100 480 ................ ................ ................ ................ ................

VM & P Naphtha ................................................................ 8032–32–4 ........... 300 1350 400 1800 ................ ................ ................

Warfarin .............................................................................. 81–81–2 ............... ................ 0.1 ................ ................ ................ ................ ................

Welding fumes (total particulate)* ...................................... N/A ....................... ................ 5 ................ ................ ................ ................ ................

Wood dust, all soft and hard woods, except Western red 

cedar.

N/A ....................... ................ 5 ................ 10 ................ ................ ................

Wood dust, western red cedar ........................................... N/A ....................... ................ 2.5 ................ ................ ................ ................ ................

Xylenes (o-, m-, p-isomers) ................................................ 1330–20–7 ........... 100 435 150 655 ................ ................ ................

m-Xylene alpha, alpha’ diamine ......................................... 1477–55–0 ........... ................ ................ ................ ................ ................ 0.1 X 

Xylidine ............................................................................... 1300–73–8 ........... 2 10 ................ ................ ................ ................ X 

Yttrium ................................................................................ 7440–65–5 ........... ................ 1 ................ ................ ................ ................ ................

Zinc chloride fume .............................................................. 7646–85–7 ........... ................ 1 ................ 2 ................ ................ ................

Zinc chromate (as CrO3); see 910.1026. See Table Z–2 

for the exposure limit for any operations or sectors 

where the exposure limit in 1910.1026 is stayed or are 

otherwise not in effect.

Varies with compound. 

Zinc oxide fume .................................................................. 1314–13–2 ........... ................ 5 ................ 10 ................ ................ ................

Zinc oxide ........................................................................... 1314–13–2. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Zinc stearate ....................................................................... 557–05–1. 

Total dust ............. ................ 10 ................ ................ ................ ................ ................

Respirable fraction ................ 5 ................ ................ ................ ................ ................

Zirconium compounds (as Zr) ............................................ 7440–67–7 ........... ................ 5 ................ 10 ................ ................ ................

1(30 minutes). 

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mstockstill on DSK4VPTVN1PROD with PROPOSALS2

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2923–2959. 

[FR Doc. 2014–24009 Filed 10–9–14; 8:45 am] 

BILLING CODE 4510–26–P 

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