30142 Federal Register / Vol. 72, No. 103 / Wednesday, May 30, 2007 / Rules and Regulations 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 82 

[EPA–HQ–OAR–2002–0064; FRL–8316–8] 

RIN 2060–AO10 

Protection of Stratospheric Ozone: 

Listing of Substitutes for OzoneDepleting Substances-n-Propyl 

Bromide in Solvent Cleaning 

AGENCY: Environmental Protection 

Agency. 

ACTION: Final Rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) determines that n-propyl 

bromide (nPB) is an acceptable 

substitute for methyl chloroform and 

chlorofluorocarbon (CFC)–113 in the 

solvent cleaning sector under the 

Significant New Alternatives Policy 

(SNAP) program under section 612 of 

the Clean Air Act. The SNAP program 

reviews alternatives to Class I and Class 

II ozone depleting substances and 

approves use of alternatives which do 

not present a substantially greater risk to 

public health and the environment than 

the substance they replace or than other 

available substitutes. 

DATES: This final rule is effective on July 

30, 2007. 

ADDRESSES: EPA has established a 

docket for this action under Docket ID 

No. EPA–HQ–OAR–2002–0064. All 

documents in the docket are listed on 

the http://www.regulations.gov Web 

site. Although listed in the index, some 

information is not publicly available, 

i.e., Confidential Business Information 

(CBI) or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available either electronically in http:// 

www.regulations.gov or in hard copy at 

the Air and Radiation Docket, EPA/DC, 

EPA West, Room 3334, 1301 

Constitution Ave., NW., Washington, 

DC. This docket facility is open from 

8:30 a.m. to 4:30 p.m., Monday through 

Friday, excluding legal holidays. The 

telephone number for the Public 

Reading Room is (202) 566–1744, and 

the telephone number for the Air and 

Radiation Docket is (202) 566–1742. 

FOR FURTHER INFORMATION CONTACT: 

Margaret Sheppard, Stratospheric 

Protection Division, Office of 

Atmospheric Programs, Mail Code 

6205J, Environmental Protection 

Agency, 1200 Pennsylvania Ave., NW., 

Washington, DC 20460; telephone 

number (202) 343–9163; fax number 

(202) 343–2362, e-mail address: 

sheppard.margaret@epa.gov. Notices 

and rulemakings under the SNAP 

program are available on EPA’s 

Stratospheric Ozone World Wide Web 

site at http://www.epa.gov/ozone/snap/ 

regs. 

SUPPLEMENTARY INFORMATION: Table of 

Contents: This action is divided into 

eight sections: 

I. General Information 

A. Does this action apply to me? 

B. What is n-propyl bromide? 

C. What acronyms and abbreviations are 

used in the preamble? 

II. How does the Significant New 

Alternatives Policy (SNAP) Program 

work? 

A. What are the statutory requirements and 

authority for the SNAP Program? 

B. How do the regulations for the SNAP 

Program work? 

C. How does the SNAP Program list our 

decisions? 

D. Where can I get additional information 

about the SNAP Program? 

III. What is EPA’s final listing decision on 

nPB in solvent cleaning? 

IV. What criteria did EPA use in making this 

Final Decision? 

A. Availability of alternatives to ozonedepleting substances 

B. Impacts on the Atmosphere and Local 

Air Quality 

C. Ecosystem and Other Environmental 

Impacts 

D. Flammability and Fire Safety 

E. Impact on Human Health 

V. How is EPA responding to comments on 

the June 2003 Notice of Proposed 

Rulemaking? 

A. EPA’s Acceptability Decision 

B. Toxicity 

C. Ozone Depletion Potential 

D. Other Environmental Impacts 

E. Flammability 

F. Legal Authority to Set Exposure Limits 

VI. How can I use nPB as safely as possible? 

VII. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation 

and Coordination with Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children from Environmental Health and 

Safety Risks 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and 

Advancement Act 

J. Congressional Review Act 

VIII. References 

I. General Information 

A. Does this action apply to me? 

This final rule lists n-propyl bromide 

(nPB) as an acceptable substitute when 

used as a solvent in industrial 

equipment for metals cleaning, 

electronics cleaning, or precision 

cleaning. General metals, precision, and 

electronics cleaning includes cleaning 

with industrial cleaning equipment 

such as vapor degreasers, in-line 

cleaning systems, or automated 

equipment used for cleaning below the 

boiling point. We understand that nPB 

is used primarily for cleaning in vapor 

degreasers. Manual cleaning, such as 

pail-and-brush, hand wipe, recirculating 

over-spray (‘‘sink-on-a-drum’’) parts 

washers, immersion cleaning into dip 

tanks with manual parts handling, and 

use of squirt bottles, is not currently 

regulated under the SNAP program. 

EPA also does not regulate the use of 

solvents as carriers for flame retardants, 

dry cleaning, or paint stripping under 

the SNAP program. 

This final action does not address the 

use of n-propyl bromide as an aerosol 

solvent or as a carrier solvent in 

adhesives or coatings. We are issuing a 

proposed rule addressing these end uses 

in a separate Federal Register action. 

Neither this final nor the proposed rule 

issue a decision on other end uses in 

which nPB was submitted as an ozonedepleting substance (ODS) substitute, 

such as fire suppression or foam 

blowing, because of insufficient 

information. 

Affected users under this final rule 

could include: 

• Businesses that clean metal parts, 

such as automotive manufacturers, 

machine shops, machinery 

manufacturers, and electroplaters. 

• Businesses that manufacture 

electronics or computer equipment. 

• Businesses that require a high level 

of cleanliness in removing oil, grease, or 

wax, such as for aerospace applications 

or for manufacture of optical equipment. 


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Federal Register / Vol. 72, No. 103 / Wednesday, May 30, 2007 / Rules and Regulations 30143 

TABLE 1.—POTENTIALLY REGULATED ENTITIES, BY NORTH AMERICAN INDUSTRIAL CLASSIFICATION SYSTEM (NAICS) 

CODE OR SUBSECTOR

Category NAICS code 

or subsector Description of regulated entities 

Industry .......................................................................... 331 Primary Metal Manufacturing. 

Industry .......................................................................... 332 Fabricated Metal Product Manufacturing. 

Industry .......................................................................... 333 Machinery Manufacturing. 

Industry .......................................................................... 334 Computer and Electronic Product Manufacturing. 

Industry .......................................................................... 335 Equipment Appliance, and Component Manufacturing. 

Industry .......................................................................... 336 Transportation Equipment Manufacturing. 

Industry .......................................................................... 337 Furniture and Related Product Manufacturing. 

Industry .......................................................................... 339 Miscellaneous Manufacturing. 

This table is not intended to be 

exhaustive, but rather a guide regarding 

entities likely to be regulated by this 

action. If you have any questions about 

whether this action applies to a 

particular entity, consult the person 

listed in the preceding section, FOR

FURTHER INFORMATION CONTACT. 

B. What is n-propyl bromide? 

n-propyl bromide (nPB), also called 1- 

bromopropane, is a non-flammable 

organic solvent with a strong odor. Its 

chemical formula is C3H7Br. Its 

identification number in Chemical 

Abstracts Service’s registry (CAS Reg. 

No.) is 106–94–5. nPB is used to remove 

wax, oil, and grease from electronics, 

metal, and other materials. It also is 

used as a carrier solvent in adhesives. 

Some brand names of products using 

nPB are: Abzol, EnSolv, and Solvon

cleaners; Pow-R-Wash NR Contact 

Cleaner, Superkleen Flux Remover 2311 

and LPS NoFlash NU Electro Contact 

Cleaner aerosols; and Whisper Spray 

and Fire Retardant Soft Seam 6460 

adhesives. 

C. What acronyms and abbreviations are 

used in the preamble? 

Below is a list of acronyms and 

abbreviations used in this document. 

8-hr—eight hour 

ACGIH—American Conference of 

Governmental Industrial Hygienists 

AEL—acceptable exposure limit 

ASTM—American Society for Testing and 

Materials 

BMD—benchmark dose 

BMDL—benchmark dose lowerbound, the 

lower 95%-confidence level bound on 

the dose/exposure associated with the 

benchmark response 

BSOC—Brominated Solvents Consortium 

CAA—Clean Air Act 

CAS Reg. No.—Chemical Abstracts Service 

Registry Identification Number 

CBI—Confidential Business Information 

CEG—community exposure guideline 

CERHR—Center for the Evaluation of Risks to 

Human Reproduction 

CFC-113—the ozone-depleting chemical 

1,1,2-trifluoro-1,2,2-trichloroethane, 

C2Cl3F3, CAS Reg. No. 76–13–1 

CFC—chlorofluorocarbon 

cfm—cubic feet per minute 

CFR—Code of Federal Regulations 

CNS—central nervous system 

DNA—deoxyribonucleic acid 

EDSTAC—The Endocrine Disruptor 

Screening and Testing Advisory 

Committee 

EPA—the United States Environmental 

Protection Agency 

FR—Federal Register 

GWP—global warming potential 

HCFC-123—the ozone-depleting chemical 

1,2-dichloro-1,1,2-trifluoroethane, CAS 

Reg. No. 306–83–2 

HCFC-141b—the ozone-depleting chemical 

1,1-dichloro-1-fluoroethane, CAS Reg. 

No. 1717–00–6 

HCFC-225ca/cb—the commercial mixture of 

the two ozone-depleting chemicals 3,3- 

dichloro-1,1,1,2,2-pentafluoropropane, 

CAS Reg. No. 422–56–0 and 1,3- 

dichloro-1,1,2,2,3-pentafluoropropane, 

CAS Reg. No. 507–55–1 

HCFC—hydrochlorofluorocarbon 

HEC—human equivalent concentration 

HFC-245fa—the chemical 1,1,3,3,3- 

pentafluoropropane, CAS Reg. No. 460–

73–1 

HFC-365mfc—the chemical 1,1,1,3,3- 

pentafluorobutane, CAS Reg. No. 405–

58–6 

HFC-4310mee—the chemical 

1,1,1,2,3,4,4,5,5,5-decafluoropentane, 

CAS Reg. No. 138495–42–8 

HFC—hydrofluorocarbon 

HFE—hydrofluoroether 

HHE—health hazard evaluation 

ICF—ICF Consulting 

ICR—Information Collection Request 

iPB—isopropyl bromide, C3H7Br, CAS Reg. 

No. 75–26–3, an isomer of n-propyl 

bromide; also called 2-bromopropane or 

2-BP 

Koc—organic carbon partition coefficient, for 

determining the tendency of a chemical 

to bind to organic carbon in soil 

LC50—the concentration at which 50% of test 

animals die 

LOAEL—Lowest Observed Adverse Effect 

Level 

Log Kow—logarithm of the octanol-water 

partition coefficient, for determining the 

tendency of a chemical to accumulate in 

lipids or fats instead of remaining 

dissolved in water 

mg/l—milligrams per liter 

MSDS—Material Safety Data Sheet 

NAICS—North American Industrial 

Classification System 

NESHAP—National Emission Standard for 

Hazardous Air Pollutants 

NIOSH—National Institute for Occupational 

Safety and Health 

NOAEL—No Observed Adverse Effect Level 

NOEL—No Observed Effect Level 

nPB-n-propyl bromide, C3H7Br, CAS Reg. No. 

106–94–5; also called 1-bromopropane or 

1-BP 

NPRM—Notice of Proposed Rulemaking 

NTP—National Toxicology Program 

NTTAA—National Technology Transfer and 

Advancement Act 

ODP—ozone depletion potential 

ODS—ozone-depleting substance 

OEHHA—Office of Environmental Health 

Hazard Assessment of the California 

Environmental Protection Agency 

OMB—U.S. Office of Management and 

Budget 

OSHA—the United States Occupational 

Safety and Health Administration 

PCBTF—parachlorobenzotrifluoride, CAS 

Reg. No. 98–56–6 

PEL—Permissible Exposure Limit 

ppm—parts per million 

RCRA—Resource Conservation and Recovery 

Act 

RFA—Regulatory Flexibility Act 

RfC—reference concentration 

SIP—state implementation plan 

SNAP—Significant New Alternatives Policy 

STEL—Short term exposure limit 

TCA—the ozone-depleting chemical 1,1,1- 

trichloroethane, CAS Reg. No. 71–55–6; 

also called methyl chloroform, MCF, or 

1,1,1 

TCE—the chemical 1,1,2-trichloroethene, 

CAS Reg. No. 79–01–6, C2Cl3H; also call 

trichloroethylene 

TERA—Toxicological Excellence for Risk 

Assessment 

TLV—Threshold Limit ValueTM

TSCA—Toxic Substances Control Act 

TWA—time-weighted average 

UMRA—Unfunded Mandates Reform Act 

U.S.C.—United States Code 

VMSs—volatile methyl siloxanes 

VOC—volatile organic compound 

WEL—workplace exposure limit 

II. How does the Significant New 

Alternatives Policy (SNAP) program 

work? 

A. What are the statutory requirements 

and authority for the SNAP program? 

Section 612 of the Clean Air Act 

(CAA) authorizes EPA to develop a 


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program for evaluating alternatives to 

ozone-depleting substances, referred to 

as the Significant New Alternatives 

Policy (SNAP) program. The major 

provisions of section 612 are: 

• Rulemaking—Section 612(c) 

requires EPA to promulgate rules 

making it unlawful to replace any class 

I (chlorofluorocarbon, halon, carbon 

tetrachloride, methyl chloroform, and 

hydrobromofluorocarbon) or class II 

(hydrochlorofluorocarbon) substance 

with any substitute that the 

Administrator determines may present 

adverse effects to human health or the 

environment where the Administrator 

has identified an alternative that (1) 

reduces the overall risk to human health 

and the environment, and (2) is 

currently or potentially available. 

• Listing of Unacceptable/Acceptable 

Substitutes—Section 612(c) also 

requires EPA to publish a list of the 

substitutes unacceptable for specific 

uses. We must publish a corresponding 

list of acceptable alternatives for 

specific uses. 

• Petition Process—Section 612(d) 

grants the right to any person to petition 

EPA to add a substitute to or delete a 

substitute from the lists published in 

accordance with section 612(c). EPA has 

90 days to grant or deny a petition. 

Where the Agency grants the petition, 

we must publish the revised lists within 

an additional six months. 

• 90-day Notification—Section 612(e) 

requires EPA to require any person who 

produces a chemical substitute for a 

class I substance to notify the Agency 

not less than 90 days before new or 

existing chemicals are introduced into 

interstate commerce for significant new 

uses as substitutes for a class I 

substance. The producer must also 

provide the Agency with the producer’s 

health and safety studies on such 

substitutes. 

• Outreach—Section 612(b)(1) states 

that the Administrator shall seek to 

maximize the use of federal research 

facilities and resources to assist users of 

class I and II substances in identifying 

and developing alternatives to the use of 

such substances in key commercial 

applications. 

• Clearinghouse—Section 612(b)(4) 

requires the Agency to set up a public 

clearinghouse of alternative chemicals, 

product substitutes, and alternative 

manufacturing processes that are 

available for products and 

manufacturing processes which use 

class I and II substances. 

B. How do the regulations for the SNAP 

program work? 

On March 18, 1994, EPA published 

the original rulemaking (59 FR 13044) 

that described the process for 

administering the SNAP program and 

issued the first acceptability lists for 

substitutes in the major industrial use 

sectors. These sectors include: 

Refrigeration and air conditioning; foam 

blowing; solvents cleaning; fire 

suppression and explosion protection; 

sterilants; aerosols; adhesives, coatings 

and inks; and tobacco expansion. These 

sectors comprise the principal industrial 

sectors that historically consumed large 

volumes of ozone-depleting substances. 

Anyone who plans to market or 

produce a substitute for an ODS in one 

of the eight major industrial use sectors 

must provide the Agency with health 

and safety studies on the substitute at 

least 90 days before introducing it into 

interstate commerce for significant new 

use as an alternative. This requirement 

applies to the person planning to 

introduce the substitute into interstate 

commerce, typically chemical 

manufacturers, but may also include 

importers, formulators or end-users 

when they are responsible for 

introducing a substitute into commerce. 

C. How does the SNAP program list our 

decisions? 

The Agency has identified four 

possible decision categories for 

substitutes: Acceptable; acceptable 

subject to use conditions; acceptable 

subject to narrowed use limits; and 

unacceptable. Use conditions and 

narrowed use limits are both considered 

‘‘use restrictions’’ and are explained 

below. Substitutes that are deemed 

acceptable with no use restrictions (no 

use conditions or narrowed use limits) 

can be used for all applications within 

the relevant sector end-use. Substitutes 

that are acceptable subject to use 

restrictions may be used only in 

accordance with those restrictions. It is 

illegal to replace an ODS with a 

substitute listed as unacceptable. 

After reviewing a substitute, the 

Agency may make a determination that 

a substitute is acceptable only if certain 

conditions of use are met to minimize 

risks to human health and the 

environment. We describe such 

substitutes as ‘‘acceptable subject to use 

conditions.’’ If you use these substitutes 

without meeting the associated use 

conditions, you use these substitutes in 

an unacceptable manner and you could 

be subject to enforcement for violation 

of section 612 of the Clean Air Act. 

For some substitutes, the Agency may 

permit a narrowed range of use within 

a sector. For example, we may limit the 

use of a substitute to certain end-uses or 

specific applications within an industry 

sector or may require a user to 

demonstrate that no other acceptable 

end uses are available for their specific 

application. We describe these 

substitutes as ‘‘acceptable subject to 

narrowed use limits.’’ If you use a 

substitute that is acceptable subject to 

narrowed use limits, but use it in 

applications and end-uses which are not 

consistent with the narrowed use limit, 

you are using these substitutes in an 

unacceptable manner and you could be 

subject to enforcement for violation of 

section 612 of the Clean Air Act. 

The Agency publishes its SNAP 

program decisions in the Federal 

Register. For those substitutes that are 

deemed acceptable subject to use 

restrictions (use conditions and/or 

narrowed use limits), or for substitutes 

deemed unacceptable, we first publish 

these decisions as proposals to allow the 

public opportunity to comment, and we 

publish final decisions as final 

rulemakings. In contrast, we publish 

substitutes that are deemed acceptable 

with no restrictions in ‘‘notices of 

acceptability,’’ rather than as proposed 

and final rules. As described in the rule 

implementing the SNAP program (59 FR 

13044), we do not believe that 

rulemaking procedures are necessary to 

list alternatives that are acceptable 

without restrictions because such 

listings neither impose any sanction nor 

prevent anyone from using a substitute. 

Many SNAP listings include 

‘‘comments’’ or ‘‘further information.’’

These statements provide additional 

information on substitutes that we 

determine are either unacceptable, 

acceptable subject to narrowed use 

limits, or acceptable subject to use 

conditions. Since this additional 

information is not part of the regulatory 

decision, these statements are not 

binding for use of the substitute under 

the SNAP program. However, regulatory 

requirements listed in this column are 

binding under other programs. The 

further information does not necessarily 

include all other legal obligations 

pertaining to the use of the substitute. 

However, we encourage users of 

substitutes to apply all statements in the 

FURTHER INFORMATION column in their 

use of these substitutes. In many 

instances, the information simply refers 

to sound operating practices that have 

already been identified in existing 

industry and/or building-code 

standards. Thus, many of the comments, 

if adopted, would not require the 

affected industry to make significant 

changes in existing operating practices. 

D. Where can I get additional 

information about the SNAP program? 

For copies of the comprehensive 

SNAP lists of substitutes or additional 

information on SNAP, look at EPA’s 


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Ozone Depletion World Wide Web site 

at http://www.epa.gov/ozone/snap/lists/ 

index.html. For more information on the 

Agency’s process for administering the 

SNAP program or criteria for evaluation 

of substitutes, refer to the SNAP final 

rulemaking published in the Federal 

Register on March 18, 1994 (59 FR 

13044), codified at Code of Federal 

Regulations at 40 CFR part 82, subpart 

G. You can find a complete chronology 

of SNAP decisions and the appropriate 

Federal Register citations at http:// 

www.epa.gov/ozone/snap/chron.html. 

III. What is EPA’s final listing decision 

on nPB in solvent cleaning? 

The Agency is listing nPB as an 

acceptable substitute in metals, 

precision and electronics cleaning end 

uses. Based on the available 

information, we find that nPB can be 

used with no substantial increase in 

overall risks to human health and the 

environment, compared to other 

available or potentially available 

substitutes for ozone-depleting 

substances in these end uses. 

EPA is issuing today’s listing in the 

form of a final rule, rather than in a 

notice of acceptability, in order to 

respond to the public comments 

received on a Notice of Proposed 

Rulemaking (NPRM) that we issued on 

June 3, 2003 (68 FR 33284). In that rule, 

we proposed listing n-propyl bromide 

(nPB) as an acceptable substitute for use 

in metals, precision, and electronics 

cleaning, and in aerosols and adhesives 

end-uses, subject to the use condition 

that nPB used in these applications 

contains no more than 0.05% by weight 

of isopropyl bromide. In addition, in 

that proposed rule, EPA indicated that 

we also would recommend that users 

adhere to a voluntary acceptable 

exposure limit (AEL) of 25 parts per 

million averaged over an eight-hour 

time-weighted average (TWA). Based on 

new information received after the close 

of the comment period on the June 2003 

NPRM relevant to our proposed 

determinations for adhesive and aerosol 

solvent end uses in that same proposal, 

the Agency is issuing a new proposal for 

those end uses in a separate Federal 

Register action. The Agency is not 

including a recommended AEL in this 

final rule. 

Table 2 contains the text pertaining to 

nPB use in solvent cleaning end-uses 

that will be added to EPA’s list of 

acceptable substitutes located on the 

SNAP Web site at http://www.epa.gov/ 

ozone/snap/lists/index.html. This and 

other listings for substitutes that are 

acceptable without restriction are not 

included in the Code of Federal 

Regulations because they are not 

regulatory requirements. The 

information contained in the ‘‘Further 

Information’’ column of those tables are 

non-binding recommendations on the 

safe use of substitutes. 

TABLE 2.—SOLVENT CLEANING ACCEPTABLE SUBSTITUTE

End use Substitute Decision Further information 

Metals cleaning, electronics 

cleaning, and precision 

cleaning.

n-propyl bromide (nPB) as 

a substitute for CFC–113 

and methyl chloroform.

Acceptable ......................... EPA recommends the use of personal protective 

equipment, including chemical goggles, flexible laminate protective gloves and chemical-resistant clothing. 

EPA expects that all users of nPB would comply with 

any final Permissible Exposure Limit that the Occupational Safety and Health Administration issues in 

the future under 42 U.S.C. 7610(a). 

nPB, also known as 1-bromopropane, is Number 106–

94–5 in the Chemical Abstracts Service (CAS) Registry. 

IV. What criteria did EPA consider in 

making this final determination? 

In the original rule implementing the 

SNAP program (March 18, 1994; 59 FR 

13044, at 40 CFR 82.180(a)(7)), the 

Agency identified the criteria we use in 

determining whether a substitute is 

acceptable or unacceptable as a 

replacement for class I or II compounds: 

(i) Atmospheric effects and related 

health and environmental impacts; [e.g., 

ozone depletion potential] 

(ii) General population risks from 

ambient exposure to compounds with 

direct toxicity and to increased groundlevel ozone; 

(iii) Ecosystem risks [e.g., 

bioaccumulation, impacts on surface 

and groundwater]; 

(iv) Occupational risks; 

(v) Consumer risks; 

(vi) Flammability; and 

(vii) Cost and availability of the 

substitute. 

In this review, EPA considered all the 

criteria above. However, n-propyl 

bromide is used in industrial 

applications such as electronics 

cleaning. In those consumer products 

made using nPB, such as a computer, 

the nPB would have evaporated long 

before a consumer would purchase the 

item. Therefore, we believe there is no 

consumer exposure risk in the end uses 

we evaluated for this rule. 

Section 612(c) of the Clean Air Act 

directs EPA to publish a list of 

replacement substances (‘‘substitutes’’) 

for class I and class II ozone depleting 

substances based on whether the 

Administrator determines they are safe 

(when compared with other currently or 

potentially available substitutes) for 

specific uses or are to be prohibited for 

specific uses. EPA must compare the 

risks to human health and the 

environment of a substitute to the risks 

associated with other substitutes that 

are currently or potentially available. In 

addition, EPA also considers whether 

the substitute for class I and class II 

ODSs ‘‘reduces the overall risk to 

human health and the environment’’

compared to the ODSs being replaced. 

Our evaluation is based on the end use; 

for example, we compared nPB as a 

metal cleaning solvent against other 

available or potentially available metal 

cleaning alternatives. 

Although EPA does not judge the 

effectiveness of an alternative for 

purposes of determining whether it is 

acceptable, we consider effectiveness 

when determining whether alternatives 

that pose less risk are available in a 

particular application within an end 

use. There are a wide variety of 

acceptable alternatives listed for solvent 

cleaning, but not all are appropriate for 

a specific application because of 

differences in soils, materials 

compatibility, degree of cleanliness 

required, local environmental 

requirements, and other factors. For 

example, aqueous cleaners are effective 

cleaners in many situations and are the 

substitute of choice for many in the 

metal cleaning end use. However, in 

some specific precision cleaning 

applications that require a high degree 

of cleanliness and that have narrow 


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1Smog, also known as ground-level ozone, is 

produced from emissions of volatile organic 

compounds that react under certain conditions of 

temperature and light. 

2Also called trichlorethene or TCE, C2Cl3H, CAS 

Reg. No. 79–01–6. 

3Also called PERC, tetrachloroethylene, or 

tetrachloroethene, C2Cl4, CAS Reg. No. 172–18–4. 

4nPB emissions in the tropics have an ODP of 

0.071 to 0.100; the portions of the U.S. outside the 

continental U.S., such as Alaska, Hawaii, Guam, 

and the U.S. Virgin Islands, contain less than 1 

percent of the U.S.’s businesses in industries that 

could use nPB. Thus, their potential impact on the 

ozone layer must be significantly less than that of 

the already low impact from nPB emissions in the 

continental U.S. (U.S. Economic Census, 2002a 

through f). 

spaces that may trap water used in 

rinsing, aqueous cleaners may not be 

appropriate and thus are not available in 

those specific applications. 

EPA evaluated each of the criteria 

separately and then considered overall 

risk to human health and the 

environment in comparison to other 

available or potentially available 

alternatives. We concluded that overall, 

while there are a number of alternatives 

that reduce the risks from ozone 

depletion or from smog production 1

slightly more than nPB when used in 

industrial solvent cleaning equipment, 

we found no single alternative that 

could work in all applications that 

clearly would reduce overall risks to 

human health and the environment in 

metals cleaning, electronics cleaning, 

and precision cleaning. Balancing the 

different criteria discussed below, nPB 

used in solvent cleaning end-uses does 

not pose a significantly greater risk than 

other substitutes or than the ODS it is 

replacing in these end uses. Thus, we 

are listing nPB as acceptable in metals 

cleaning, electronics cleaning, and 

precision cleaning. 

A. Availability of Alternatives to OzoneDepleting Substances 

Other alternatives to methyl 

chloroform and CFC–113 are available 

for metals, electronics, and precision 

cleaning that have already been found 

acceptable or acceptable subject to use 

conditions under the SNAP program 

including: Aqueous cleaners, semiaqueous cleaners, alcohols, ketones, 

esters, ethers, terpenes, HCFC–225ca/cb, 

hydrofluoroethers (HFEs), 

hydrofluorocarbon (HFC)–4310mee, 

HFC–365mfc, heptafluorocyclopentane, 

hydrocarbons, volatile methyl siloxanes 

(VMSs), trans-1,2-dichloroethylene, 

methylene chloride, trichloroethylene 2

(TCE), perchloroethylene,3

parachlorobenzotrifluoride (PCBTF), 

and alternative technologies like 

supercritical fluids, plasma cleaning, 

and ultraviolet/ozone cleaning. Some 

alternatives are unlikely to be used in 

particular end uses because of 

constraints such as cleaning 

performance, materials compatibility, 

cost, workplace exposure requirements, 

or flammability. For example, no-clean 

technology is used in electronics 

cleaning and not in precision cleaning 

because of the need for a high degree of 

cleanliness in precision cleaning. Of the 

available substitutes, aqueous cleaners 

or solvents for vapor degreasing such as 

TCE, blends of alcohols or trans-1,2- 

dichloroethylene and HFCs or HFEs, 

and HCFC–225ca/cb are most likely to 

be used in the same applications as nPB. 

nPB is already commercially available 

in solvent cleaning, and is used mostly 

for vapor degreasing in the electronics 

and precision cleaning end uses (IBSA, 

2002). 

B. Impacts on the Atmosphere and 

Local Air Quality 

As discussed in the June 2003 

proposal, nPB emissions from the 

continental United States are estimated 

to have an ozone depletion potential 

(ODP) of approximately 0.013–0.018, 

(Wuebbles, 2002) 4, lower than that of 

the ozone depletion potential of the 

substances that nPB would replace—

CFC–113 (ODP=1.0), and methyl 

chloroform and HCFC–141b (ODPs = 

0.12) (WMO, 2002). Some other 

acceptable alternatives for these ODSs 

also have low ODPs. For example, 

HCFC–225ca/cb has an ODP of 0.02–

0.03 (WMO, 2002) and is acceptable in 

metals cleaning and aerosol solvents, 

and acceptable subject to use conditions 

in precision cleaning and electronics 

cleaning. HCFC–123 has an ODP of 0.02 

(WMO, 2002), and is an acceptable 

substitute in precision cleaning. There 

are other acceptable cleaners that 

essentially have no ODP—aqueous 

cleaners, HFEs, HFC–4310mee, HFC–

365mfc, HFC–245fa, hydrocarbons, 

VMSs, methylene chloride, TCE, 

perchloroethylene, and PCBTF. 

The global warming potential (GWP) 

index is a means of quantifying the 

potential integrated climate forcing of 

various greenhouse gases relative to 

carbon dioxide. Earlier data found a 

direct 100-year integrated GWP (100yr 

GWP) for nPB of 0.31 (Atmospheric and 

Environmental Research, Inc., 1995). 

More recent analysis that considers both 

the direct and the indirect GWP of nPB 

found a 100-yr GWP of 1.57 (ICF, 2003a; 

ICF, 2006a). In either case, the GWP for 

nPB is comparable to or below that of 

previously approved substitutes in these 

end uses. 

Use of nPB may be controlled as a 

volatile organic compound (VOC) under 

state implementation plans (SIPs) 

developed to attain the National 

Ambient Air Quality Standards for 

ground-level ozone, which is a 

respiratory irritant. Users located in 

ozone non-attainment areas may need to 

consider using a substitute for cleaning 

that is not a VOC or if they choose to 

use a substitute that is a VOC, they may 

need to control emissions in accordance 

with the SIP. Companies have 

petitioned EPA, requesting that we 

exempt nPB from regulation as a VOC. 

However, unless and until EPA issues a 

final rulemaking exempting a 

compound from the definition of VOC 

and states change their SIPs to exclude 

such a compound from regulation, that 

compound is still regulated as a VOC. 

Other acceptable ODS-substitute 

solvents that are VOCs for state air 

quality planning purposes include most 

oxygenated solvents such as alcohols, 

ketones, esters, and ethers; 

hydrocarbons and terpenes; 

trichloroethylene; trans-1,2- 

dichloroethylene; monochlorotoluenes; 

and benzotrifluoride. Some VOCexempt solvents that are acceptable ODS 

substitutes include HFC–245fa for 

aerosol solvents; HCFC–225ca/cb, HFC–

365mfc and HFC–4310mee for metals 

electronics, and precision cleaning and 

aerosol solvents; and methylene 

chloride, perchloroethylene, HFE–7100, 

HFE–7200, PCBTF, acetone, and methyl 

acetate for metals, electronics, and 

precision cleaning, aerosol solvents, 

adhesives, and coatings. 

C. Ecosystem and Other Environmental 

Impacts 

EPA considered the possible impacts 

of nPB if it were to pollute soil or water 

as a waste and compared these impacts 

to screening criteria developed by the 

Endocrine Disruptor Screening and 

Testing Advisory Committee (EDSTAC, 

1998) (see Table 3). Available data on 

the organic carbon partition coefficient 

(Koc), the breakdown processes in water 

and hydrolysis half-life, and the 

volatilization half-life indicate that nPB 

is less persistent in the environment 

than many solvents and would be of low 

to moderate concern for movement in 

soil. Based on the LC50, the acute 

concentration at which 50% of tested 

animals die, nPB’s toxicity to aquatic 

life is moderate, being less than that for 

some acceptable cleaners (for example, 

trichloroethylene, hexane, d-limonene, 

and possibly some aqueous cleaners) 

and greater than that for some others 

(methylene chloride, acetone, isopropyl 

alcohol, and some other aqueous 

cleaners). The LC50 for nPB is 67 mg/l, 

which is greater than 10 mg/l. Based on 

EPA’s criteria for listing under the 

Toxics Release Inventory (U.S. EPA, 


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1992), we believe that nPB would not be 

sufficiently toxic to aquatic life to 

warrant listing under the Toxics Release 

Inventory. Based on its relatively low 

bioconcentration factor and log Kow

value, nPB is not prone to 

bioaccumulation. Table 3 summarizes 

information on environmental impacts 

of nPB; trans-1,2-dichloroethylene, a 

commonly-used solvent in blends for 

aerosol solvents, precision cleaning, and 

electronics cleaning; trichloroethylene, 

a solvent used for metals, electronics, 

and precision cleaning; and methyl 

chloroform, an ODS that nPB would 

replace. 

TABLE 3.—ECOSYSTEM AND OTHER ENVIRONMENTAL PROPERTIES OF NPB AND OTHER SOLVENTS

Property Description of environmental property Value for nPB 

Value for trans1,2-dichloro-ethylene 

Value for trichloroethylene Value for methyl 

chloroform 

Koc, organic-carbon 

partition coefficient.

Degree to which a substance tends to 

stick to soil or move in soil. Lower 

values (< 300)* indicate great soil 

mobility; values of 300 to 500 indicate moderate mobility in soil.

330 (Source: ICF, 

2004a).

32 to 49 (Source: 

ATSDR, 1996).

106 to 460 

(Source: 

ATSDR, 1997).

152 (Source: U.S. 

EPA, 1994a). 

Break down in 

water.

Mechanism and speed with which a 

compound breaks down in the environment. (Hydrolysis half-life values 

> 25 weeks* are of concern.) 

Hydrolysis is significant. Hydrolysis half-life of 

26 days 

(Source: ICF, 

2004a).

Photolytic decomposition, 

dechlorination 

and biodegradation are significant; hydrolysis 

not significant 

(Source: 

ATSDR, 1996).

Volatilization and 

biodegradation 

most significant, 

with hydrolysis 

relatively insignificant. Hydrolysis half-life of 

10.7 to 30 

months (Source: 

ATSDR, 1997).

Volatilization most 

significant; biodegradation and 

hydrolysis also 

occur (Source: 

ATSDR, 2004). 

Volatilization halflife from surface 

waters.

Tendency to volatilize and pass from 

water into the air.

3.4 hours-4.4 days 

(Source: ICF, 

2004a).

3 to 6.2 hours 

(Source: 

ATSDR, 1996).

3.4 hours to 18 

days (Source: 

ATSDR, 1997).

Hours to weeks 

(Source: U.S. 

EPA, 1994a). 

LC50 (96 hours) for 

fathead minnows.

Concentration at which 50% of animals die from toxicity after exposure for 4 days.67 mg/L (Source: 

Geiger, 1988).

108 mg/L (Source: 

U.S. EPA, 1980).

40.7 to 66.8 mg/L 

(Source: NPS, 

1997).

52.8 to 105 mg/L 

(Source: U.S. 

EPA, 1994a). 

log Kow .................. Logarithm of the octanol/water partition coefficient, a measure of tendency to accumulate in fat. Log Kow

values >3* indicate high tendency 

to accumulate.

2.10 (Source: ICF, 

2004a).

¥0.48 (Source: 

LaGrega et al., 

2001, p. 1119).

2.38 (Source: 

LaGrega et al., 

2001, p. 1127).

2.50 (Source: 

LaGrega et al., 

2001, p. 1127). 

Bioconcentration 

factor.

High factors (>1000)* indicate strong 

tendency for fish to absorb the 

chemical from water into body tissues.

23 (Source: 

HSDB, 2004).

5 to 23 (Source: 

ATSDR, 1996).

10 to 100 (Source: 

ATSDR, 1997).

<9 (Source: U.S. 

EPA, 1994a). 

*Criteria from EDSTAC, 1998. 

nPB is not currently regulated as a 

hazardous air pollutant and is not listed 

as a hazardous waste under the 

Resource Conservation and Recovery 

Act (RCRA). nPB is not required to be 

reported as part of the Toxic Release 

Inventory under Title III of the 

Superfund Amendments and 

Reauthorization Act. Despite this, large 

amounts of nPB might be harmful if 

disposed of in water. We recommend 

that users dispose of nPB as they would 

dispose of any spent halogenated 

solvent (F001 waste under RCRA). Users 

should not dump nPB into water, and 

should dispose of it by incineration. 

D. Flammability and Fire Safety 

A number of commenters on the June 

2003 proposal provided additional 

information on the flammability of nPB 

using standard test methods for 

determining flash point, such as the 

American Society for Testing and 

Materials (ASTM) D 92 open cup, 

ASTM D56 Tag closed cup, and ASTM 

D93 Pensky-Martens closed cup 

methods (BSOC, 2000; Miller, 2003; 

Morford, 2003a, b and c; Shubkin, 2003; 

Weiss Cohen, 2003). We agree with the 

commenters that by these standard test 

methods, nPB displayed no flash point. 

Thus under standard test conditions, 

nPB is not flammable, and it should not 

be flammable under normal use 

conditions. With its low potential for 

flammability, nPB is comparable to 

chlorinated solvents, HCFCs, HFEs, 

HFC–245fa, HFC–4310mee, and 

aqueous cleaners, and is less flammable 

than many acceptable substitutes, such 

as ketones, alcohols, terpenes, and 

hydrocarbons. nPB exhibits lower and 

upper flammability limits of 

approximately 3% to 8% (BSOC, 2000). 

A number of other solvents that are 

typically considered to be nonflammable also have flammability limits 

(for example, methylene chloride, 

HCFC–141b, and methyl chloroform). If 

the concentration of vapor of such a 

solvent falls between the upper and 

lower flammability limits, it could catch 

fire in presence of a flame. Such a 

situation is unusual, but users should 

take appropriate precautions in cases 

where the concentration of vapor could 

fall between the flammability limits. 

E. Impact on Human Health 

In evaluating potential human health 

impacts of nPB, EPA considered 

impacts on both exposed workers and 

on the general population because we 

identified these groups of people as the 

ones likely to be exposed to nPB when 

it is used as a substitute for ozonedepleting substances. EPA evaluated the 

available toxicity data using EPA 

guidelines to develop health-based 

criteria to characterize human health 

risks (U.S. EPA, 1994b. RfC Guidelines; 

U.S. EPA, 1991. Guidelines for 

Developmental Toxicity Risk 

Assessment; U.S. EPA, 1995b. 

Benchmark Dose guidelines; U.S. EPA, 

1996. Guidelines for Reproductive 

Toxicity Risk Assessment). 


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In the June 2003 NPRM, EPA 

proposed that an exposure limit of 25 

ppm would be protective of a range of 

effects observed in animal and human 

studies, including reproductive and 

developmental toxicity, neurotoxicity, 

and hepatotoxicity. Reduction of sperm 

motility in rats, noted across multiple 

studies at relatively low exposures, was 

determined to be the most sensitive 

effect. The Agency derived an exposure 

limit of 18 ppm from a dose response 

relationship in male rat offspring (‘‘F1 

generation’’) whose parents were 

exposed to nPB from prior to mating 

through birth and weaning of the litters 

(WIL Research Laboratories, 2001). We 

then proposed to adjust this value 

upwards to 25 ppm based on principles 

of risk management consistent with one 

of the original ‘‘Guiding Principles’’ of 

the SNAP program (59 FR 13046, March 

18, 1994). As we discussed in the June 

2003 NPRM, EPA noted that adhesives 

users should be able to achieve an AEL 

of 25 ppm and that 25 ppm was between 

the level based on the most sensitive 

endpoint (sperm motility in the F1 

offspring generation) and the second 

most sensitive endpoint (sperm motility 

in the F0 parental generation). 

Following SNAP program principles, we 

noted that ‘‘a slight adjustment of the 

AEL may be warranted after applying 

judgment based on the available data 

and after considering alternative 

derivations’’ (69 FR 33295). We stated 

further that ‘‘18 ppm is a reasonable but 

possibly conservative starting point, and 

that exposure to 25 ppm would not pose 

substantially greater risks, while still 

falling below an upper bound on the 

occupation[al] exposure limit.’’

As part of this final rulemaking, the 

Agency has reviewed both information 

available at the time of the 2003 NPRM 

related to the health risks associated 

with nPB use, as well as more recent 

case studies of nPB exposures and 

effects in the workplace, newly 

published toxicological studies, 

comments to the NPRM, new risk 

assessments on nPB, and a new 

threshold limit value (TLV) issued by 

the American Council of Government 

and Industrial Hygienists (ACGIH). The 

new information is reviewed in greater 

detail in EPA’s proposal specific to the 

use of nPB in aerosol solvents, 

adhesives, and coatings. 

Some general conclusions we draw 

from the new studies include: 

• New data from toxicological studies 

on nervous system effects remain 

inconsistent and equivocal concerning 

the level at which nervous system 

effects occur (Fueta et al., 2002; Fueta et 

al., 2004; Honma et al., 2003; Ishidao et 

al., 2002, NTP, 2003; Sohn et al. 2002, 

Wang et al., 2003). 

• Case reports of nPB exposure in the 

workplace indicate that severe, possibly 

irreversible, neurological effects may 

occur at sustained concentrations of 

approximately 100 ppm or greater (Beck 

and Caravati, 2003; Majersik et al., 2004; 

Majersik et al., 2005; Ichihara et al., 

2002; Miller, 2005; Raymond and Ford, 

2005). In other cases, similar or higher 

concentrations up to 170 ppm caused 

less severe nervous system effects 

(Nemhauser, 2005; NIOSH, 2003a; 

Ichihara, 2004a). Some neurological 

effects occurred in workers at levels of 

less than 50 ppm (Ichihara et al., 2004b). 

Because of design and methodological 

limitations, such as small numbers of 

subjects and limited exposure 

information, these studies do not 

provide a sufficient quantitative basis to 

derive an acceptable exposure limit. 

• Data on female rats indicate that 

nPB affects the maturation of ovarian 

follicles and the ovarian cycle (Yamada 

et al., 2003), consistent with previously 

reviewed data (WIL, 2001; Sekiguchi et 

al., 2002). 

• Some data on occupation exposure 

suggest that workers exposed to nPB 

may have experienced menstrual 

disorders (Ichihara et al., 2002; Ichihara 

et al., 2004b). However, the data are not 

statistically significant and are not 

sufficient to conclude that nPB exposure 

caused these female reproductive 

effects. 

• Data on DNA damage in workers 

exposed to nPB was not statistically 

significant (Toraason et al., 2006). 

• Metabolic data on mice and rats 

indicate some species differences. 

Metabolism of nPB appears to be 

primarily through cytochrome P450 

enzymes, particularly in mice; 

glutathione conjugation also plays a 

role, and a bigger role for rats than for 

mice (RTI, 2005). 

These more recent studies do not cause 

us to change our acceptability 

determination for solvent cleaning. 

In addition, we considered new 

evaluations of the toxicity of nPB from 

Stelljes and Wood (2004), Toxicological 

Excellence in Risk Assessment (TERA, 

2004), ICF (2004a, 2006a), and the TLV 

documentation from the ACGIH 

(ACGIH, 2005). 

• Stelljes and Wood (2004) is similar 

in its results to SLR International (2001), 

a study by the same authors. EPA 

previously reviewed SLR International, 

2001 in developing the June 2003 

NPRM. Both these studies concluded 

with a recommended AEL of 156 ppm, 

based on male reproductive effects and 

uncertainty factors of 1 in driving the 

AEL. These documents assigned 

uncertainty factors in a manner 

inconsistent with EPA’s guidance. This 

would result in a higher AEL than we 

would determine following the 

approach EPA has used on other 

chemicals, as well as an AEL that in our 

view would not sufficiently protect 

human health from nPB’s effects 

because of multiple sources of 

uncertainty in available data (i.e., 

variability within the working 

population and differences between 

animals and humans in how nPB affects 

the reproductive system). 

• TERA (2004) reviews other AEL 

derivations for nPB, performs a 

benchmark dose (BMD) analysis, and 

recommends an AEL of 20 ppm based 

on live litter size. This document is 

consistent with EPA guidance for BMD 

modeling and for assigning uncertainty 

factors. A review of this document is 

available in the public docket (ICF, 

2004b). 

• ICF (2004c, 2006b) derived an AEL 

for nPB based upon female reproductive 

effects. ICF (2004c, 2006b) discussed the 

relevant literature (Ichihara et al., 1999, 

2002, 2004a, 2004b; Sekiguchi, 2002; 

Yamada et al., 2003; WIL, 2001) and 

calculated mean estrous cycle length 

and the mean number of estrous cycles 

occurring during a three-week period at 

different exposure levels in the WIL, 

2001 2-generation study. ICF (2004c, 

2006a) found statistically significant 

reductions in the number of estrous 

cycles in a three-week period, both 

including and excluding females that 

had stopped their estrous cycles, at 250, 

500, and 750 ppm in the F0 parental 

generation and at 500 and 750 ppm in 

the F1 generation. ICF (2004c, 2006a) 

conducted BMD modeling and 

calculated benchmark dose lowerbound 

(BMDL) values of the number of estrous 

cycles in a three-week period that varied 

from 102 to 208 ppm, depending upon 

the model used and the benchmark 

criteria selected. All data were 

calculated based on the mean 

reductions in estrous cycle number 

calculated from the WIL, 2001 study. 

Values were calculated for the F0 

generation; the number of data for the 

F1 generation was too small for 

statistical analysis. The BMDLs that ICF 

calculated for the number of estrous 

cycles in a three-week period were 162 

ppm and 208 ppm, depending on the 

benchmark response criteria (10% 

change in response vs. one standard 

deviation) and using a linearheterogeneous model. 

• The ACGIH issued a recommended 

TLV of 10 ppm (time-weighted average) 

for nPB (ACGIH, 2005). ACGIH 

summarized numerous studies showing 


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5 Vendors of nPB-based products have 

recommended a wide range of exposure limits, from 

5 ppm to 100 ppm (Albemarle, 2003; Chemtura, 

2006; Docket A–2001–07, item II–D–19; Enviro 

Tech International, 2006; Farr, 2003; Great Lakes 

Chemical Company, 2001). 

6By EPA guidelines, we would apply an 

uncertainty factor of √10, or approximately 3, for 

differences between species for all health effects. 

We would also apply an uncertainty factor of √10 

(3) for variability within the working population for 

reproductive and developmental effects, because, 

among other reasons, these conditions would not 

necessarily screen out an individual from being able 

to work, unlike for liver or nervous system effects. 

Therefore, for reproductive and developmental 

effects, we use a composite uncertainty factor of 10. 

See further discussion of uncertainty factors in 

section V.B.3 below. 

different effects of nPB and identified 

no observed effect levels (NOELs) of 200 

ppm for hepatotoxicity (ClinTrials, 

1997b) and less than 100 ppm for 

developmental toxicity, as evidenced by 

decreased fetal weight (Huntingdon Life 

Sciences, 2001). 

The Occupational Safety and Health 

Administration (OSHA) has not 

developed a permissible exposure limit 

(PEL) for nPB that EPA could use to 

evaluate toxicity risks 5 from workplace 

exposure. In prior SNAP reviews, EPA 

has used ACGIH TLVs where available 

in assessing a chemical’s risks and 

determining its acceptability if OSHA 

has not set a PEL. ACGIH is recognized 

as an independent, scientifically 

knowledgeable organization with 

expertise in issues of toxicity and 

industrial hygiene. However, in this 

case, EPA believes that ACGIH’s TLV for 

nPB of 10 ppm has significant 

limitations as a reliable basis for an 

acceptable exposure limit, especially 

given the availability of other, more 

comprehensive analyses described in 

this preamble. First, according to the 

authors of the Huntingdon Life Sciences 

study, the decrease in fetal weight was 

an artifact of sampling procedure that 

biased the data (test animals were only 

sacrificed at the end of the day rather 

than at random). The Center for the 

Evaluation of Risks to Human 

Reproduction (CERHR) expert panel 

excluded ‘‘aberrantly low’’ fetal weights 

from one litter in this study and 

calculated a BMDL greater than 300 

ppm for this endpoint after removing 

those outlier data (CERHR, 2002a, 

2003a, and 2004a). TERA calculated a 

BMDL similar to that of the CERHR 

expert panel when analyzing the same 

data set (TERA, 2004). Further, the 

reference list in the documentation on 

the TLV indicates that ACGIH did not 

review and evaluate all the studies 

available prior to the development of 

the recommended exposure limit. For 

example, key supporting articles that 

reported disruption of estrous cycles 

(Yamada et al., 2003 and Sekiguchi et 

al., 2002) were not discussed in the TLV 

documentation. Further, ACGIH did not 

provide sufficient reasoning for the 

selection of the chosen endpoint over 

others (e.g., reproductive toxicity and/or 

neurotoxicity). The lack of discussion of 

applied uncertainty factors also 

prevents a determination of how ACGIH 

arrived at a TLV of 10 ppm. In 

summary, EPA is not basing its 

proposed acceptability determination 

for nPB on the ACGIH TLV because: (1) 

Other scientists evaluating the database 

for nPB did not find the reduced pup 

weight to be the most sensitive 

endpoint; (2) BMD analysis of the 

reduced pup weight data (CERHR, 

2002a; TERA, 2004) results in a higher 

BMDL (roughly 300 ppm) than those for 

sperm effects and estrous cycle changes; 

and (3) ACGIH may not have reviewed 

the complete body of literature as 

several studies discussing neurotoxicity 

and female reproductive effects were 

omitted from the list of references. A 

number of reviews of this document are 

available in the public docket (ICF, 

2004d; O’Malley, 2004). Despite some 

flaws in its derivation, the TLV of 10 

ppm is less than two-fold lower than the 

low end of the range of acceptable 

exposure levels based on the most 

sensitive reproductive endpoints (see 

below). This small difference is well 

within the uncertainty we see when 

extrapolating a benchmark dose from an 

experimental study in rats to an 

occupational exposure limit in humans. 

We summarize the data for a number 

of end points found in these analyses in 

Table 4 below. We examined these data 

to assess the acceptability of nPB use in 

the metals, electronics, and precision 

cleaning end uses reviewed in this final 

rule. These data indicate that, once 

uncertainty factors are applied 

consistent with EPA guidelines, the 

lowest levels for acceptable exposures 

would be derived for reproductive 

effects.6 The data also indicate that a 

level sufficient to protect against male 

reproductive effects (e.g., reduced sperm 

motility) would be in a range from 18 

to 30 ppm, in the range of 17 to 22 ppm 

to protect against female reproductive 

effects (e.g., estrous cycle length), and at 

approximately 20 ppm for effects related 

to reproductive success (live litter size). 

TABLE 4.—SUMMARY OF ENDPOINTS USING BENCHMARK RESPONSE MODELING

Endpoint a Study BMDLb

(ppm) 

Human 

equivalent 

concentration 

(HEC)c

(ppm) 

Liver Effects d

Liver vacuolation in males (F1 offspring generation).WIL, 2001 as analyzed in ICF, 2002 .............................................................. 110 116 

Liver vacuolation in males (F0 parent 

generation).

WIL, 2001 as analyzed in ICF, 2002 .............................................................. 143 150 

Liver vacuolation ................................ ClinTrials, 1997b as analyzed in ICF, 2002 and Stelljes & Wood, 2004 ....... 226 170 

Reproductive Effects—Male 

Sperm motility (F1 offspring generation).WIL, 2001 as analyzed in ICF, 2002 .............................................................. 169 177 

WIL, 2001 as analyzed in Stelljes & Wood, 2004 .......................................... 156 164 

Sperm motility (F0 parent generation) WIL, 2001 as analyzed in ICF, 2002 .............................................................. 282 296 

WIL, 2001 as analyzed in Stelljes & Wood, 2004 .......................................... 263 276 

Prostate weight (F0 parent generation).WIL, 2001 as analyzed in TERA, 2004 .......................................................... 190 200 

Sperm count ....................................... Ichihara et al., 2000b as analyzed in Stelljes & Wood, 2004 ........................ 232 325 


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TABLE 4.—SUMMARY OF ENDPOINTS USING BENCHMARK RESPONSE MODELING—Continued 

Endpoint a Study BMDLb

(ppm) 

Human 

equivalent 

concentration 

(HEC)c

(ppm) 

Sperm deformities (F0 parent generation).WIL, 2001 as analyzed in Stelljes & Wood, 2004 .......................................... 296 311 

Reproductive Effects—Female 

Number of estrus cycles during a 3 

week period (F0 parent generation).

WIL, 2001 as analyzed in ICF, 2006a ............................................................ 162 170 

WIL, 2001 as analyzed in ICF, 2006a ............................................................ 208 218 

Estrous cycle length (F1 offspring 

generation) d.

WIL, 2001 as analyzed in TERA, 2004 .......................................................... 400 420 

Estrous cycle length (F0 parent generation) e.WIL, 2001 as analyzed in TERA, 2004 .......................................................... 210 220 

No estrous cycle incidence (F1 offspring generation).WIL, 2001 as analyzed in TERA, 2004 .......................................................... 180 189 

No estrous cycle incidence (F0 parent 

generation).

WIL, 2001 as analyzed in TERA, 2004 .......................................................... 480 504 

Reproductive Effects—Reproductive Success 

Decreased live litter size (F1 offspring 

generation).

WIL, 2001 as analyzed in TERA, 2004 .......................................................... 190 200 

Decreased live litter size (F2 offspring 

generation).

WIL, 2001 as analyzed in TERA, 2004 .......................................................... 170 179 

Pup weight gain, post-natal days 21 

to 28 (F1 offspring generation).

WIL, 2001 as analyzed in TERA, 2004 .......................................................... 180 189 

Developmental Effects 

Fetal body weight ............................... WIL, 2001 as analyzed in TERA, 2004 .......................................................... 310 326 

Fetal body weight ............................... WIL, 2001 as analyzed in CERHR, 2002a ..................................................... 305 320 

Nervous System Effects 

Hindlimb strength ............................... Ichihara et. al., 2000a as analyzed in Stelljes and Wood, 2004 ................... 214 300 

a Unless explicitly stated, data are from a parental generation. Of the studies analyzed, only the WIL, 2001 study has multiple generations to 

be analyzed. bThe benchmark response value represents a specified level of excess risk above a control response. 

cWhen considering workplace exposures, the human equivalent concentration is the BMDL, adjusted to apply to a 40-hour work week in which 

workers are exposed for 8 hours a day for five days per week. Animals in the WIL, 2001 study were exposed for 6 hours a day, 7 days a week. 

Animals in the Ichihara, 2000a and 2000b studies were exposed for 8 hours a day, 7 days a week. Animals in the ClinTrials, 1997b study were 

exposed for 6 hours a day, 5 days a week. dAfter applying an uncertainty factor of 3 for animal to human extrapolation, acceptable levels of exposure to protect against liver effects would 

be in the range of 39 to 57 ppm. eOmits data from those animals that have stopped estrous cycling altogether (TERA, 2004). 

These more recent evaluations do not 

change EPA’s acceptability 

determination for solvent cleaning. As 

discussed below, users of solvent 

cleaning equipment are reliably able to 

achieve exposure levels well below our 

proposed AEL of 25 ppm in the June 

2003 NPRM and therefore we expect 

nPB users in the metals, electronics, and 

precision cleaning end uses to be able 

to achieve acceptable exposure levels. 

Concentrations of nPB emitted from 

industrial solvent cleaning equipment 

were found to be below 25 ppm in 

roughly 88% of 500 samples on an 8-hr 

time-weighted average, below 18 ppm in 

81% of these samples, and below 10 

ppm in roughly 70% of these samples 

(U.S. EPA, 2003). 

Based on review of the previously 

available information and information 

submitted in comments to the NPRM, 

the Agency believes that its derivation 

of 18 ppm as a starting point in the 

development of a recommended 

acceptable exposure level is still valid. 

For purposes of assessing the 

acceptability of nPB use in solvent 

cleaning applications, the Agency 

evaluated whether exposure levels 

expected to result from solvent cleaning 

would approach either the 2003 

proposed recommended AEL of 25 ppm, 

or the more conservative starting point 

of 18 ppm which was derived from the 

Agency’s original risk analysis. We also 

evaluated any potential risks to the 

general population associated with nPB 

use as a solvent. 

1. Workplace Risks 

EPA believes that the great majority of 

users of nPB in metals cleaning, 

electronics cleaning, and precision 

cleaning have been able to attain 

exposure levels of well below 25 ppm, 

the proposed AEL in the 2003 NPRM, 

with their existing equipment. Recently 

measured exposure levels for nPB are 

much lower than historic exposure data 

from the 1970s and 1980s for metals 

cleaning and electronics cleaning (ICF, 

2006a); this reflects both improvements 

in industrial hygiene practices and 

improvements in cleaning equipment 

since 1994 spurred by the National 

Emission Standard for Hazardous Air 

Pollutants for Halogenated Solvent 

Cleaning (59 FR 61801). Concentrations 


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of nPB emitted from industrial solvent 

cleaning equipment were found to be 

below 25 ppm in roughly 88% of 500 

samples on an 8-hr time-weighted 

average, below 18 ppm in 81% of these 

samples, and below 10 ppm in roughly 

70% of these samples (U.S. EPA, 2003). 

One nPB supplier provided evidence 

that on the few occasions when nPB 

concentrations from vapor degreasers 

were higher than the company’s 

recommended AEL of 25 ppm, users 

were able to reduce exposure easily and 

inexpensively by changing work 

practices, such as reducing drafts near 

the cleaning equipment (Kassem, 2003). 

The ability to meet the workplace 

exposure limit depends on: (1) The 

features of the cleaning equipment used, 

such as the presence of secondary 

cooling coils; and (2) the work practices, 

such as avoiding drafts near cleaning 

equipment and lifting cleaned pieces 

out slowly from the cleaning equipment. 

Workplace controls could include, but 

are not limited to, the use of the 

following: Covers on cold-cleaning and 

vapor degreasing equipment when not 

in use; devices to limit air movement 

over the degreaser; and/or a lip-vent 

exhaust system to capture vapors and 

vent them out of the room. Training 

workers in industrial hygiene practices 

and in the proper use of cold cleaning 

and vapor degreasing equipment, as 

well as warning workers of the 

symptoms that may occur from overexposure to nPB, will also help reduce 

exposure. Therefore, we expect that 

users of nPB in the solvent cleaning 

sector following typical industry 

practices and using typical equipment 

for vapor degreasing will continue to 

meet acceptable exposure levels and to 

use nPB safely without regulatory 

requirements. This is the approach the 

SNAP program has taken with many 

other solvents where users are readily 

able to meet workplace exposure limit 

that will protect human health and there 

is no enforceable OSHA PEL (e.g., HFC–

365mfc, HFC–245fa, 

heptafluorocyclopentane, ketones, 

alcohols, esters, hydrocarbons, etc.). 

Based on the available exposure data 

and current industry practices, EPA 

believes that users of nPB as an 

industrial solvent for metals cleaning, 

electronics cleaning, and precision 

cleaning are likely to be exposed to 

concentrations of nPB well below the 

proposed AEL of 25 ppm from the 2003 

NPRM. 

2. General Population Risks 

In the 2003 NPRM, the Agency 

provided analyses demonstrating that 

people living in the immediate vicinity 

of a facility using nPB in spray 

adhesives would have exposures below 

the community exposure guideline of 

1 ppm (68 FR 33300–33301). The 

community exposure guideline was 

derived considering both sperm motility 

and liver effects in the WIL (2001) 2- 

generation study using EPA’s reference 

concentrations (RfC) guidelines (U.S. 

EPA, 1994b). Since the general 

population would not be exposed in 

excess of the community exposure 

guideline from a highly emissive 

application, the less emissive uses such 

as metals, electronics, and precision 

cleaning would create insignificant 

exposures (well below 1 ppm). Thus, we 

believe that proper use of nPB in solvent 

cleaning would not pose measurable 

risks to the general population. 

V. How is EPA responding to comments 

on the June 2003 NPRM? 

In this section, EPA responds to 

comments on the major issues in the 

June 2003 NPRM. A complete response 

to comments is in docket EPA–HQ–

OAR–2002–0064. 

A. EPA’s Acceptability Decision 

There was no consensus among 

commenters about whether EPA should 

find nPB acceptable, acceptable subject 

to use conditions, or unacceptable in the 

various end uses listed in the proposal. 

Some commenters raised concerns 

about specific end uses, particularly 

aerosols and adhesives. Others 

supported finding nPB acceptable in 

solvents cleaning and in adhesives. We 

are not taking final action in this rule 

with respect to nPB as a substitute in 

aerosols or adhesives. We will respond 

to any comments regarding those end 

uses at the time we take final action for 

aerosols and adhesives. 

Comment: Several commenters 

supported EPA’s proposed approval of 

nPB under the SNAP program in various 

end uses. In contrast, two commenters 

opposed EPA’s proposed acceptability 

determination in all end uses, including 

solvent cleaning, citing concerns about 

exposure and the toxicity of nPB. 

Another commenter stated that 

applications cited in the proposal (e.g., 

electronics and metals cleaning, label 

removal and spray cleaning) are not 

suitable for use of nPB. This commenter 

reasoned that if nPB provides unique 

performance characteristics, its uses 

should be limited to non-emissive and 

low-volume applications. A commenter 

from a company that markets nPB as a 

chemical intermediate but not as a 

solvent, noted that his company 

recognizes the health concerns 

associated with nPB, and thus his 

company continues to prohibit the sale 

of nPB to customers with dispersive 

uses. Another commenter stated that 

nPB is dangerous to the ozone layer and 

workers and urged EPA to find a safe 

substitute. 

Response: EPA believes nPB may be 

found acceptable under the SNAP 

program only in those end uses where 

it has been shown to be used safely, as 

compared with other substitutes that are 

currently or potentially available. We 

find this to be the case for metals 

cleaning, electronics cleaning, and 

precision cleaning. 

Comment: Several commenters agreed 

with EPA’s proposed approval for nPB 

in metal cleaning, electronics cleaning, 

and precision cleaning end uses. One 

specifically reported that his company’s 

industrial hygiene program for nPBbased solvents in metal and electronics 

cleaning has conducted extensive air 

sampling, and that the majority of the 

samples have shown values well below 

25 ppm. This commenter also noted 

that, in those few workplaces where 

higher levels were found, adoption of 

recommended workplace ventilation 

and handling practices produced 

acceptable subsequent sample values. 

Thus, this commenter believes that 

exposures can be controlled to 

protective levels. 

One commenter expressed concerns 

over the approval of nPB as acceptable 

for use in solvent cleaning, maintaining 

that toxicity data is insufficient to be 

convincing that long-term effects will 

not be a concern. Two other 

commenters did not support EPA’s 

proposal to find nPB acceptable. One of 

the commenters concurred with EPA 

that exposures from manual wipe 

cleaning will not be acceptable and that 

nPB should not be used in such 

operations. Another commenter 

opposed EPA’s proposed acceptability 

determination for solvent cleaning, 

stating that use of nPB in applications 

such as electronics and metals cleaning, 

label removal, and spray cleaning is not 

appropriate. 

Response: EPA agrees with those 

commenters who said nPB should be 

acceptable for use in metal cleaning, 

electronics cleaning, and precision 

cleaning. By our definition of the 

solvent cleaning sector, such users are 

cleaning using industrial cleaning 

equipment. For an organic solvent, this 

means a vapor degreaser or an 

automated cold cleaning machine. 

Emissions from vapor degreasers can be 

controlled both through improving 

equipment (increasing the freeboard, 

adding cooling coils, or adding a lift that 

raises cleaned pieces slowly) and 

through improved work practices 

(leaving the vicinity of the vapor 

degreaser when done with work, tipping 


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7We interpret the commenter’s use of the term 

‘‘equal protection’’ to mean that the commenter 

beleives that EPA has performend a harsher review 

of nPB than it has for other substitutes and not a 

claim that EPA has violated the 14th Amendment 

of the Constitution, which applies only to the states 

and not the Federal Government. 

work-pieces so they do not catch 

solvent, or lifting cleaned pieces out 

slowly). 

In solvent cleaning equipment, 

exposure data show that nPB can meet 

an exposure level well below 25 ppm, 

even at levels of 5 ppm or less, the 

majority of the time (U.S. EPA 2003; 

ICF, 2006a). Concentrations of nPB 

emitted from industrial solvent cleaning 

equipment were measure to be below 25 

ppm in roughly 88% of more than 500 

samples, below 18 ppm in 81% of these 

samples, and at or below 5 ppm in 56% 

of these samples (U.S. EPA, 2003). In 

cases where exposure levels are higher, 

there are simple, cost-effective changes 

that can be made to reduce emissions 

(Kassem, 2003). We agree that manual 

cleaning using nPB is inappropriate, 

because of the difficulty of controlling 

emissions, but manual cleaning is 

currently beyond the scope of the SNAP 

Program. EPA plans to address spray 

cleaning using aerosols in a new 

proposal. 

B. Toxicity 

1. Health Endpoints 

Comment: A number of commenters 

on the June 2003 NPRM suggested that 

EPA should consider neurotoxicity as 

the endpoint in deriving the AEL for 

nPB (Linnell, 2003; Werner, 2003; 

Rusch and Bernhard, 2003; Rusch, 

2003). In particular, they requested that 

EPA consider the study conducted by 

Wang (2003) and epidemiological data 

on neurotoxic effects of nPB. 

Response: Recent data collected from 

occupational settings indicate that 

severe, possibly irreversible, 

neurological effects may occur at 

sustained concentrations of 

approximately 100 ppm or greater (Beck 

and Caravati, 2003; Majersik, 2004; 

Majersik, 2005), with variability in 

effects observed in different studies, 

although in most cases exposures may 

have been much higher. Other studies 

with human data are discussed above in 

section IV.E. Because of design and 

methodological limitations, such as 

small numbers of subjects and limited 

exposure information, none of the 

recent studies individually provides a 

sufficient quantitative basis to derive an 

AEL. 

In the study on rats by Wang et al. 

(2003), measurements found a decrease 

in enzymes in the spinal cord and brain 

at 200, 400, and 800 ppm, but the 

animals displayed no physical or 

behavioral changes. Because of the lack 

of physical symptoms or behavioral 

changes, EPA does not believe that the 

decrease in enzyme levels in the central 

nervous system are toxicologically 

relevant. Other studies examining 

neurological effects of nPB showed 

those effects to be transient and 

reversible at and above 200 ppm 

(Ichihara et al., 2000a). Exposures of 200 

ppm and above for three weeks had no 

effect on memory, learning function, or 

coordination of limbs (Honma, 2003); 

the effect of spontaneous locomotor 

activity seen in this study at 50 ppm 

and above was not considered adverse 

by the authors. In other studies, 

neurological effects were absent after 

extended periods of exposure—after 28 

days of exposure at concentrations > 

400 ppm (ClinTrials, 1997a) and after 90 

days of exposure at concentrations up to 

600 ppm (ClinTrials, 1997b). Thus, 

although neurological effects have been 

associated with nPB exposure, the data 

are currently insufficient to quantify 

and set an AEL based on this endpoint. 

More recent data does not change EPA’s 

acceptability determination for solvent 

cleaning. 

Comment: One commenter on the 

June 2003 NPRM requested that EPA 

evaluate a study by Yamada et al (2003), 

a study published just prior to the June 

2003 NPRM. 

Response: EPA reexamined Yamada et 

al., 2003 and re-evaluated the literature 

(Ichihara et al., 1999, 2002, 2004a,b; 

Sekiguchi, 2002, Yamada et al., 2003; 

WIL, 2001). Multiple benchmark 

analyses found a statistically significant 

decrease in the number of estrous cycles 

and increase in estrous cycle length 

associated with nPB exposure, 

consistent with other reproductive 

endpoints, namely reductions in sperm 

motility, decreased live litter size, and 

change in prostate weight (ICF, 2002a; 

ICF, 2006a; Stelljes and Wood, 2004; 

TERA, 2004). These more recent 

evaluations, which could lead to an 

HEC of 170 ppm and an AEL of 17 ppm, 

do not change EPA’s acceptability 

determination for solvent cleaning, 

since the evidence supports the ability 

of users in this end use to consistently 

meet such a level. 

Comment: Some commenters stated 

that data from the F1 generation is 

inappropriate for calculating 

occupational exposure, citing 

statements from some toxicologists that 

use of effects on adult F1 generation 

animals is inappropriate. They also 

stated that EPA has not required this for 

other chemicals and that the resulting 

value is more conservative than what is 

normal and appropriate for industrial 

toxicology (Morford, 2003d and e; 

Ruckriegel, 2003). One commenter 

claims that because EPA’s review of nPB 

differed from EPA’s review of other 

SNAP alternatives, the process violates 

equal protection (Morford, 2003d and e). 

Others stated that sperm motility effects 

on the F1 generation are appropriate to 

consider (Risotto, 2003; Farr, 2003), 

particularly because of the potential for 

in utero effects and because of the 

consistent presence of these 

reproductive effects in both generations 

and at multiple levels. 

Response: EPA is not finalizing a 

specific AEL for the purposes of this 

final rule. EPA acknowledges that using 

data from the F1 offspring generation 

may be conservative because the pups 

in the F1generation were exposed to 

nPB between weaning and sexual 

maturity (WIL, 2001). During 

occupational exposure, this period of 

exposure would not occur because 

children under age 16 are not allowed 

to work in industrial settings. However, 

EPA believes that because of the 

potential for in utero effects that would 

only be seen in the offspring generation, 

looking only at the F0 parental 

generation could underestimate the 

adverse health impacts of a chemical. 

Therefore, it was appropriate for us to 

consider effects seen in both the F0 

parental generation and the F1 offspring 

generation. Further, effects on sperm 

motility in the parental and offspring 

generations are seen at levels generally 

consistent with multiple reproductive 

effects seen in both generations and 

both sexes exposed to nPB, such as 

estrous cycle length, lack of estrous 

cycling, the number of estrous cycles in 

a given period of time, fertility indices, 

and the number of live pup births 

(TERA, 2004; ICF, 2006a; SLR 

International, 2001). 

We also note that different substances 

have different toxicological effects and 

those effects must be considered based 

on the best scientific information and 

methodologies available. It is incorrect 

to claim that such reviews, which focus 

on the effects of different substances, 

resulted in disparate treatment of nPB7. 

2. Adjustments to Acceptable Exposure 

Level Based on Risk Management 

Principles 

In the 2003 NPRM, EPA derived 18 

ppm as the starting point for an 

acceptable exposure level based on 

reduced sperm motility in the offspring 

generation of animals exposed to nPB 

(WIL, 2001). Following a SNAP program 

principle that alternatives should be 

restricted only where it is ‘‘clearly more 

harmful to human health and the 


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8Pharmacodynamics refers to the biochemical 

and physiological effects of chemicals in the body 

and the mechanism of their actions. 

9Pharmacokinetics refers to the activity or fate of 

chemicals in the body, including the processes of 

absorption, distribution, localization in tissues, 

biotransformation, and excretion. 

10The blood/air partition coefficient is the ratio 

of a chemical’s concentration between blood and air 

when at equilibrium. 

environment than other alternatives,’’

we noted that ‘‘a slight adjustment of 

the AEL may be warranted after 

applying judgment based on the 

available data and after considering 

alternative derivations’’(69 FR 33294, 

33295). The Agency proposed an 

upward adjustment of the AEL to 25 

ppm based on principles of risk 

management, and based, among other 

things, on a determination that 25 ppm 

was between the level based on the most 

sensitive endpoint (sperm motility in 

the F1 offspring generation) and the 

second most sensitive endpoint (sperm 

motility in the F0 parental generation). 

We stated further that ‘‘18 ppm is a 

reasonable but possibly conservative 

starting point, and that exposure to 25 

ppm would not pose substantially 

greater risks, while still falling below an 

upper bound on the occupation[al] 

exposure limit.’’

Comment: Commenters responded 

that: (1) The SNAP program does not 

create a presumption in favor of 

substances that are already available on 

the market, especially where other 

alternatives exist (Linnell, 2003; 

Werner, 2003); (2) EPA’s AEL derivation 

of 18 ppm is not conservative enough 

(Werner, 2003; Risotto, 2003) and 

further adjustment upward further 

reduces protection; (3) the data do not 

support adjusting the AEL upward 

(EPA–HQ–OAR–2002–0064–0003); (4) 

EPA should first use the same 

methodology in establishing an AEL as 

for other chemicals to ensure that the 

program’s guiding principle in 

comparing risks is not compromised 

(Werner, 2003); and (5) EPA should 

reconsider whether industrial exposures 

consistently occur or can be controlled 

at 25 ppm (Werner, 2003). No 

commenters specifically supported 

adjusting the AEL upward. 

Response: EPA is not finalizing a 

specific AEL for the purposes of this 

final rule. In a separate proposed 

rulemaking for the aerosol, adhesive and 

coatings end uses, we will be providing 

the public an opportunity to comment 

on a range of exposure level values that 

are comparable to the levels discussed 

in the June 2003 proposal (69 FR 33295) 

that the Agency would consider to be 

acceptable. Because we have concluded 

that end users in the solvent sector are 

routinely able to meet even the lowest 

exposure level we considered 

recommending (U.S. EPA, 2003), we do 

not need to make a final determination 

as to the appropriate level for purposes 

of this rulemaking. 

3. Uncertainty Factors 

According to EPA risk assessment 

guidance for RfC (EPA 1994a), 

uncertainty factors of up to 10 may be 

applied to the ‘‘human equivalent 

concentrations (which accounts for 

worker exposure patterns of 8 hours per 

day for 5 days a week), for each of the 

following conditions: 

(1) Data from animal studies are used 

to estimate effects on humans; 

(2) Data on healthy people or animals 

are adjusted to account for variations in 

sensitivity among members of the 

human population (inter-individual 

variability); 

(3) Data from subchronic studies are 

used to provide estimates for chronic 

exposure; 

(4) Studies that only provide a LOAEL 

rather than a NOAEL or BMD; or 

(5) An incomplete database of toxicity 

information exists for the chemical. 

Comment: Some commenters on the 

June 2003 NPRM stated that EPA should 

use an uncertainty factor of 1 or 2 to 

extrapolate from animals to humans 

(Weiss Cohen, 2003), while others 

suggested uncertainty factors of 2 or 3 

for pharmacokinetics, or an overall 

uncertainty factor of 10 for rat to human 

extrapolation because of a lack of 

information on the metabolism and 

mode of action of nPB and because the 

rat is an insensitive model for effects on 

male reproduction in humans (Werner, 

2003; Rusch and Bernhardt, 2003). 

Response: EPA believes that two 

uncertainty factors are appropriate for 

this database to account for (1) 

physiological differences between 

humans and rats; and (2) variability 

within the working population. EPA RfC 

guidelines state that an uncertainty 

factor of 10 may be used for potential 

differences between study animals and 

humans. This factor of 10 consists in 

turn of two uncertainty factors of 3—the 

first to account for differences in 

pharmacodynamics8 and the second to 

account for differences in 

pharmacokinetics9 between the study 

animal and humans. (The value of three 

is the square root of 10 rounded to one 

digit, with 10 representing an order of 

magnitude [EPA,1994a, pp. 1–6, 4–73]. 

In practice, EPA uses the square root of 

10 when there are two or four 

uncertainty factors of 3, yielding a total 

uncertainty factor of 10 or 100, and we 

use a value of 3 when multiplying by 

other uncertainty factors.) In general, 

EPA’s RfC guidelines state that for the 

uncertainty factor extrapolating from 

animal to human data, ‘‘Use of a 3 is 

recommended with default dosimetric 

adjustments.’’ (U.S. EPA, 1994b, p. 4–

73). By EPA RfC guidelines (US EPA, 

1994b), no adjustment for differences in 

pharmacokinetics is necessary in this 

instance because the blood/air partition 

coefficient 10 for nPB in the human (7.1) 

is less than in the rat (11.7), indicating 

that the delivered dose of nPB into the 

bloodstream in rats is slightly higher 

than in humans. EPA has seen no data 

to indicate that (1) the toxicity is not 

directly related to the inhaled parent 

compound in the arterial blood, or that 

(2) the critical metabolic pathways do 

not scale across species, with respect to 

body weight, in the same way as the 

ventilation rate. Consistent with 

Appendix J of EPA’s RfC guidelines for 

an inhaled compound that exerts its 

effects through the bloodstream, EPA 

applies an uncertainty factor of 1 for 

pharmacokinetics and an uncertainty 

factor of 3 for differences between 

animals and humans. 

Recent studies provide additional 

data regarding metabolism of nPB in rats 

and mice (RTI, 2005), but data on 

human metabolism are still lacking. One 

analysis of these metabolic data 

suggested that mice are less sensitive to 

the effects of nPB than rats and 

hypothesized that humans would also 

be less sensitive than rats (Stelljes, 

2005). This analysis makes numerous 

assumptions about toxic nPB 

metabolites and metabolic activation 

pathways that have not been confirmed 

by experimental data. A review of this 

analysis is available in the public docket 

(ICF, 2006c). Despite the difference in 

metabolic pathways for nPB in mice and 

rats (RTI, 2005), EPA finds no 

significant species-specific differences 

in toxicity exist between rats and mice 

at inhaled concentrations <500 ppm for 

13 weeks (NTP, 2003; ICF, 2006c). 

However, these metabolic and 

subchronic inhalation studies 

conducted under the National 

Toxicology Program did not specifically 

examine for reproductive toxicity or 

nPB metabolism in target organs that 

control reproductive function. In 

summary, there is little available data 

about the metabolic activation or 

reactive metabolites responsible for 

reproductive toxicity in rodents. 

Similarly, for nPB, there is little 

information available about differences 

and similarities between rodents and 

humans. Given this circumstance, EPA 

assumes, in the absence of evidence to 

the contrary, that nPB toxicity is 

directly related to the inhaled parent 


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compound in the arterial blood and that 

the critical metabolic pathways scale 

across species in a manner similar to the 

ventilation rate (U.S. EPA, 1994b). 

Therefore, the Agency applied an 

uncertainty factor of 1 to account for 

interspecies differences in 

pharmacokinetics. 

Given the available data on the blood/ 

air partition coefficient and EPA RfC 

guidance in the absence of other 

information, EPA is applying the same 

rationale used for other compounds 

reviewed under EPA’s SNAP program 

with a comparable amount of data 

where an uncertainty factor of 1 for 

pharmacokinetics was applied. To 

account for uncertainty in 

pharmacodynamics of nPB, EPA is 

applying the default uncertainty factor 

of 3. This follows the procedures in 

EPA’s RfC guidelines for situations 

where there are no data to compare 

pharmacodynamics in rats versus 

humans (U.S. EPA, 1994b). Recently 

published data on humans and rodents 

do not decrease the uncertainty 

regarding the pharmacodynamics of 

nPB; therefore, modification of the 

uncertainty factor of 3 for differences 

between species was not justified. 

Comment: One commenter stated that 

EPA did not cite any data that describes 

the size, condition, or existence of a 

subpopulation of men especially 

sensitive to the effects of nPB. In 

addition, this commenter asserted that 

sensitive populations are not 

traditionally considered when deriving 

an OEL, and that EPA has never 

mentioned a concern with sensitive 

subpopulations in previous SNAP 

reviews. Another commenter said that 

there is no evidence to support the 

assertion that nPB exposure below a 100 

ppm average will further reduce sperm 

count or that the removal of nPB 

exposure will improve sperm count. 

Response: EPA disagrees with the 

comments. There are preexisting 

reproductive conditions as well as 

significant variability in fertility among 

otherwise healthy adults in the 

workplace. Both male and female 

reproduction have been shown to be 

adversely affected by aging, with effects 

on the ovarian cycle and on sperm 

motility as major factors changing with 

increasing age for women and men, 

respectively (Dunson et al., 2002). 

Adding damage from other factors, such 

as smoking or occupational exposure to 

chemicals such as nPB, therefore, can 

potentially harm an individual’s ability 

to reproduce further (Dunson, et al. 

2002). EPA did not issue a proposal 

based on sperm count, so that comment 

is not relevant to this rule. In addition, 

we note that EPA has used uncertainty 

factors in the past to protect sensitive 

subpopulations on other chemicals 

reviewed under the SNAP program (e.g., 

trifluoroiodomethane at 60 FR 31092, 61 

FR 25585 and IoGasTM Sterilant Blends 

at 69 FR 58903). For deriving AELs from 

health endpoints such as liver effects 

and neurotoxicity, the SNAP program 

typically has assigned an uncertainty 

factor of 1 for sensitive subpopulations 

because we assume that individuals 

who are especially susceptible to these 

effects will have greater difficulty 

working than most people. However, 

there is no connection between the 

ability to reproduce and the ability to 

work in the industrial sectors discussed 

in this rule. Thus, we find it appropriate 

to require an uncertainty factor greater 

than 1 for reproductive effects for 

variability within the working 

population. 

Comment: Some commenters said that 

an uncertainty factor of 1 is appropriate 

for variability within the working 

population because sensitive 

subpopulations will not be present in 

the working population (Stelljes, 2003, 

Morford, 2003e). Other commenters 

stated that there will be very little 

difference in variability between the 

worker population and the general 

population and that it is unclear why 

EPA selected an uncertainty factor of 3 

instead of 10 (Werner, 2003). 

Commenters suggested uncertainty 

factors for variability in the working 

population of 1, 2, and 5 (Stelljes, 2003, 

Weiss Cohen, 2003, Werner, 2003). 

Response: EPA disagrees with the 

commenters. EPA’s RfC guidelines 

recommend an uncertainty factor of 10 

to account for intraspecies variability 

within the general population. However, 

in developing an AEL, EPA’s focus is on 

worker exposure, which excludes some 

particularly vulnerable populations, 

such as children, most adolescents, and 

the elderly. Thus, we believe that a full 

uncertainty factor of 10, as for the 

general population, may be higher than 

necessary to protect workers. Certain 

individuals in the general population 

but not in the working population that 

might be particularly vulnerable would 

include children and adolescents under 

age 16 and individuals with immune 

deficiency disorders. However, because 

of variability in reproductive function 

due to factors present among workers, 

such as aging, smoking, and sexually 

transmitted disease (Dunson et al., 

2002), and because there is no screening 

of workers that would make workers 

more likely to have healthy 

reproductive systems than non-workers 

of the same age, we believe than an 

uncertainty factor of 1 is not sufficiently 

protective. Under EPA guidelines, 3 is a 

default value for an uncertainty factor 

where there is indication that a value 

less than an order of magnitude (10) but 

greater than one is appropriate, and 

where the available data are not 

sufficiently quantified to select a 

specific value. 

4. Other Analyses of nPB’s Toxicity 

Comment: One commenter stated that 

documents by Drs. Doull, Rozman, 

Stelljes, Murray, Rodricks, and the KS 

Crump Group were not acknowledged 

(Morford, 2003d,e, and f). Another 

commenter requested that EPA take into 

account the scientific presentations 

presented by Drs. Doull, Rozman and 

Stelljes and mentions a review by Dr. 

Rodricks (Weiss Cohen, 2003). 

Response: EPA specifically mentioned 

and responded to the occupational 

exposure limit recommendations from 

Drs. Rozman, Doull, and Stelljes in the 

preamble to the June 2003 NPRM at 68 

FR 33298–33299. In addition, EPA 

included more detailed written 

responses to these derivations and the 

evaluation by Dr. Rodricks in the online 

docket prior to proposal (EPA–HQ–

OAR–2002–0064–0017, –0018, and 

–0019). Here are abbreviated responses 

to the various documents cited by the 

commenter: 

• Drs. Doull and Rozman’s letter 

dated August 24, 2001, stating that a 

two-generational reproductive study is 

not appropriate (Docket A–2001–07, 

item II–D–26)—Drs. Doull and Rozman 

do not provide a rationale for their 

statement. Their statement is in conflict 

with their AEL derivation, in which 

they consider use of the F1 generation 

of the WIL Laboratories two-generation 

study. As discussed above in section 

V.B.1, EPA believes that data from a 

two-generation reproductive study are 

appropriate in developing a guideline 

for the workplace in order to assure that 

workers and their children are protected 

from any adverse health effects of 

workplace exposure, including exposure 

in utero. We acknowledge that this 

value may be more conservative than 

considering data only from the parental 

generation. 

• Drs. Doull and Rozman’s critique of 

ICF’s AEL derivation (II-D–41b)—Drs. 

Doull and Rozman’s primary stated 

reason for rejecting ICF Consulting’s 

evaluation is that it does not reflect their 

own AEL derivation. They reiterate that 

they find neurotoxicity to be the 

appropriate basis for an AEL without 

addressing the reasons that ICF’s 

derivation provides for finding 

reproductive toxicity to be of greater 

concern than neurotoxicity. We disagree 

with Doull and Rozman’s conclusion 

that neurotoxicity is the more 


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appropriate endpoint for several 

reasons: (1) The human data are 

insufficient to draw conclusions 

because of a small number of subjects, 

limited exposure information, and lack 

of statistical significance; (2) the animal 

data on neurotoxicity are inconsistent 

and equivocal concerning the level at 

which nervous system effects occur, and 

they indicate that neurotoxic effects 

may be reversible; and (3) neurotoxicity 

is a less sensitive endpoint than 

reproductive effects. However, if we had 

used neurotoxicity as the endpoint for 

an AEL, we would have reached the 

same acceptability determination for 

solvent cleaning. 

The basis of EPA’s June 2003 NPRM 

is different from either one of these 

documents because it uses a different 

endpoint from Doull and Rozman’s 

derivation (2001) and an uncertainty 

factor of 3 instead of 2 to 3 for 

variability within the working 

population (Doull and Rozman, 2001; 

ICF, 2002a). According to EPA guidance 

on establishing uncertainty factors, if a 

uncertainty factor is between 1 and 10 

and the data are not sufficient to 

quantify the uncertainty between those 

values, the default uncertainty factor to 

be used is 3 (U.S. EPA, 1994b). 

• Drs. Rozman and Doull’s derivation 

of an AEL (II–D–63)—EPA discussed 

our evaluation of this document at 

length in the preamble of the June 2003 

NPRM at 68 FR 33298. In particular, we 

disagree with Rozman and Doull’s 

selection of the most sensitive endpoint. 

Rozman and Doull concluded that 

reproductive toxicity should not be 

considered the most sensitive endpoint, 

stating that a National Institute for 

Occupational Safety and Health 

(NIOSH) evaluation found that no 

human beings at a facility using nPBbased adhesives experienced 

reproductive health effects from the 

nPB. However, the NIOSH study in fact 

concluded that the survey questions 

would not be sufficient to determine if 

there were reproductive health effects, 

which is significantly different from 

saying that there was no health effect. 

The expert panel for the CERHR looked 

at the NIOSH report and a wide range 

of human and animal studies on nPB; in 

contrast to Rozman and Doull, the 

expert panel concluded that there was 

insufficient information on reproductive 

effects of nPB on humans and that the 

results of tests on animals were 

considered appropriate for evaluating 

potential reproductive health effects on 

humans. 

Further, EPA disagrees with the 

specific AEL value of 60 to 90 ppm that 

Rozman and Doull derived. They used 

data on headaches from a draft NIOSH 

survey, selecting an endpoint of 190 

ppm. However, the data in the final 

survey were not sufficient to detect any 

dose-response with any statistical 

significance (Custom Products HHE, II–

A–49). Further, more recent studies on 

human exposure to nPB have found 

neurotoxic effects occurring at levels at 

least as low as 86 ppm, and possibly 

lower than 60 ppm (Ichihara 2004a, 

Beck and Caravati 2003). These data 

would indicate that an AEL of 60 to 90 

ppm is not sufficiently protective 

against neurotoxic effects. Drs. Rozman 

and Doull themselves now suggest that 

an AEL of 25 ppm may be more 

appropriate for protecting against 

neurotoxic effects (Rozman and Doull, 

2005). 

• Dr. Rodricks’ AEL derivation and 

comments on ICF’s derivation (II–D–

65)—EPA reviewed Rodricks (2002) in 

developing its June 2003 NPRM, 

although the study was not explicitly 

mentioned in that preamble. Rodricks 

(2002) suggests an AEL of 60 to 88 ppm 

for nPB, based on male reproductive 

effects. Dr. Rodricks says that the most 

sensitive endpoint that is relevant for 

occupational exposure is data from the 

parent generation of the two-generation 

reproductive study. Dr. Rodricks 

suggests that an uncertainty factor of 

only 1 to 2 is necessary for animal to 

human extrapolation because one 

should consider animals and workers of 

average sensitivity; although such an 

argument presumably could be made for 

any chemical used in the workplace, 

EPA has not seen other AEL derivations 

that use this approach. Dr. Rodricks 

appears to agree with ICF that an 

uncertainty factor for variability in 

reproductive function in the human 

population is reasonable, although he 

suggests a factor of 2 instead of the 

range of 2 to 3 in ICF’s derivation. Dr. 

Rodricks and colleagues previously 

recommended an AEL for nPB of less 

than 10 ppm, and at that time suggested 

an uncertainty factor of 10 for variability 

in reproductive function in the human 

population (A–91–42, X–B–53). We 

discussed above the use of data from 

both the F0 and F1 generations and the 

use of an uncertainty factor of 3 for 

variability within the working 

population. 

• Dr. Stelljes’s critique of ICF’s AEL 

derivation (II–D–41a)—Dr. Stelljes states 

that ICF should have used data from the 

parent generation rather than from the 

offspring generation because ‘‘data from 

F1 animals is not directly applicable to 

a workplace exposure setting because 

both parents would not be exposed to 

nPB on a daily basis over the 

reproductive cycle, and also have their 

offspring exposed daily from weaning.’’

EPA disagrees in part with Dr. Stelljes’s 

reasoning. Data from F0 animals may 

not be sufficiently protective because 

effects on the F0 animals will not reflect 

effects of in utero exposure. However, 

we agree that exposure during weaning 

is not reflective of workplace exposure, 

and thus, data from F1 animals may be 

conservative. EPA proposed 25 ppm 

instead of 18 ppm in part to take this 

conservatism into account. 

• Dr. Stelljes’s (SLR International’s) 

AEL derivation (II–D–13)—EPA 

discussed this AEL derivation at length 

in the preamble to the proposed rule at 

68 FR 33298. We agreed with Dr. 

Stelljes’s BMD modeling and his 

selection of reduced sperm motility in 

the F1 offspring generation of the WIL 

Laboratories study as the most sensitive 

endpoint. However, we disagree with 

Dr. Stelljes’s selection of uncertainty 

factors. There is no information showing 

that human sex cells are less sensitive 

to nPB than rat sex cells, and there is 

considerable evidence that human 

males have less reproductive capacity 

than male rats (U.S. EPA, 1996). 

Therefore, it is appropriate to add an 

uncertainty factor of at least 3 to 

account for differences between rats and 

humans. Further, Stelljes dismisses the 

use of an uncertainty factor for 

differences within the human 

population. Although we agree that 

children and the elderly would not be 

present in the workplace as sensitive 

subpopulations, there certainly is 

variability in the reproductive abilities 

of different working-age people that 

would have no impact on the 

individual’s ability to be hired or to 

work; therefore, EPA expects there is 

some variability in the susceptibility of 

working individuals to the effects of 

reproductive toxicants. EPA believes 

that male reproductive capacity is very 

susceptible to chemical insult (U.S. 

EPA, 1996). 

• Dr. Murray’s opinion on parent and 

offspring generations (II–D–58)—Dr. 

Murray says that because the offspring 

generation will not yet have developed 

sperm while in utero, it is more 

appropriate to use data from the parent 

generation of the two-generation study. 

However, Dr. Murray does not address 

the possibility that nPB exposure during 

pregnancy could influence the 

production of hormones that eventually 

would result in sperm production. 

Further, Dr. Murray’s response does not 

address potential effects on ova, which 

would be present while a fetus is still 

in its mother’s womb. 

• Report on uncertainty factors used 

by ACGIH from K.S. Crump Group (IV–

D–26/OAR–2002–0064–0047 and –48)—

This report concluded that EPA’s 


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11 iPB is also referred to as 2-bromopropane, 2- 

propyl bromide, or 2-BP. Its CAS registry number 

is 75–26–3. 

approach to selecting uncertainty factors 

for use in risk assessment was more 

transparent, with justification for each 

value selected, and was more consistent 

than the values apparently used by the 

ACGIH in deriving TLVs. EPA agrees 

with these conclusions. 

Comment: A commenter states that 

‘‘an uncertainty factor of 10 is NOT 

‘generally’ used to derive occupational 

exposure limits and that in fact, 

uncertainty factors of 3 or less or more 

commonly used,’’ citing the K. S. Crump 

Group’s report. 

Response: In the case of the TLV that 

ACGIH established for nPB, ACGIH 

appears to set an AEL that is a factor of 

10 lower than the endpoint cited as 

lowest (100 ppm for effects on pup 

weight) (ACGIH, 2005). Thus, ACGIH 

has used an approach for nPB consistent 

with the total uncertainty factor of 10 

assigned by EPA. 

5. Overall Stringency of the Acceptable 

Exposure Limit 

Comment: Some commenters 

supported the proposed AEL of 25 ppm, 

stating that it was derived using 

appropriate conservative and cautious 

scientific processes. Other commenters 

said that the proposed AEL of 25 ppm 

was too high, citing uncertainties in the 

data, the inappropriateness of adjusting 

the AEL upward from 18 ppm, reports 

of health effects on humans, and a need 

for higher uncertainty factors. Other 

commenters said that the proposed AEL 

of 25 ppm was too low, citing higher 

AELs derived by Drs. Stelljes, Doull, 

Rozman, and Rodricks, NIOSH studies, 

and a need for lower uncertainty factors. 

Commenters suggested alternate AEL 

values ranging from 1 ppm to 156 ppm. 

Response: In this final rule, EPA is 

not recommending an acceptable 

exposure limit. We have based our 

determination of acceptability by 

comparing measured exposure levels 

from workers using nPB in solvent 

cleaning to exposure levels discussed by 

EPA in the proposal (see section IV.E). 

At the levels discussed in the NRPM or 

higher, we find nPB acceptable for 

solvent cleaning. After considering the 

available scientific studies on toxicity, 

exposure data, and alternative 

derivations of the acceptable exposure 

limit, we find that the exposure levels 

discussed in 2003 provide sufficient 

protection for human health and are 

consistent with EPA’s derivations of 

AELs for other chemicals reviewed 

under the SNAP program and EPA 

guidance for risk assessment. 

6. Skin Absorption 

In the June 2003 NPRM, EPA 

discussed listing nPB with a skin 

notation, and proposed that this was not 

necessary (68 FR 33295). 

Comment: Several commenters on the 

June 2003 proposal stated that a skin 

notation for nPB is appropriate, while 

another commenter agreed with EPA’s 

proposal that no skin notation was 

necessary (Smith, 2003; HESIS, 2003; 

Werner, 2003, Weiss Cohen, 2003). One 

commenter said that EPA should require 

manufacturers, distributors, and 

marketers of nPB-containing products to 

communicate such information on the 

Material Safety Data Sheets (MSDS) and 

the product label. 

Response: We agree with the 

commenter that said a skin notation is 

not necessary. However, today’s 

decision includes a recommendation for 

users to wear protective clothing and 

flexible laminate gloves when using nPB 

to address the concerns about dermal 

exposure. 

Rat studies indicate that dermal 

exposure to nPB results in neither 

appreciable absorption through the skin 

(RTI, 2005) nor systemic toxicity (Elf 

Atochem, 1995). Unlike methyl chloride 

and dichlorvos, which are absorbed 

through the skin and could contribute to 

systemic toxicity (ACGIH, 1991), EPA is 

not including a skin notation for nPB in 

the information provided to users 

associated with this rulemaking because 

of the relatively low level of absorption. 

The ACGIH provides no skin notation in 

its TLV documentation for several 

solvents, including nPB (ACGIH, 2005), 

methylene chloride, and 

perchloroethylene, and there is no 

evidence that absorption through the 

skin is greater for nPB than for the other 

halogenated compounds. The TLV 

documentation for nPB states, ‘‘There is 

no basis for a skin notation because the 

dermal LD50 of 1-BP was >2 g/kg.’’

Further, including a statement giving 

advice about how to reduce skin 

exposure in the ‘‘Further Information’’

column of listings is likely to be more 

informative to workers than a skin 

notation. 

Given the possibility that some nPB 

can be absorbed through the skin in 

humans, and that the solvent can irritate 

the skin, EPA encourages users to wear 

protective clothing and flexible laminate 

gloves when using nPB and encourages 

manufacturers, distributors, and 

marketers of nPB-containing products to 

include such precautions in their 

MSDSs. EPA believes that our 

regulatory authority for the SNAP 

program is over the substitution (use) of 

ozone-depleting substances, and thus, 

we do not believe we have sufficient 

authority to regulate the manufacturers, 

distributors and marketers of nPB. 

7. Iso-Propyl Bromide Limit 

In the June 2003 proposed rule, we 

proposed as a use condition that nPB 

formulations contain no more than 

0.05% isopropyl bromide (iPB) 11 by 

weight because of potential health 

effects associated with this isomer (68 

FR 33301–33302). 

Comment: Two commenters said that 

0.05% iPB is an appropriate and 

achievable limit. (Smith, 2003; Weiss 

Cohen, 2003). One of these commenters 

stated that industry test studies showed 

that lower limits were neither 

toxicologically justified nor economical. 

Another commenter opposed the 

implementation of the proposed use 

restriction, stating that it places an 

undue legal burden on end users, rather 

than the manufacturers of raw materials, 

and would not benefit worker safety. 

This commenter also stated that this is 

the only instance that SNAP has 

regulated residual contaminants. This 

commenter also suggested that EPA 

defer to an AEL of 1 ppm for iPB 

established by the government of Korea 

and the Japan Society for Occupational 

Health. Moreover, this commenter said 

that the difference between the 

acceptable iPB exposure determined by 

EPA and that determined by ASTM–

D6368–00 is very small and, thus, EPA’s 

proposed regulation does not add any 

value to existing standards. Finally, this 

commenter noted that epidemiological 

data found no adverse effect on human 

workers exposed to 110 ppm of iPB 

(Ichihara, specific study not identified 

by the commenter). (Morford, 2003g and 

h). 

Response: We agree that industry has 

achieved this contamination limit for 

several years without regulation. We 

also agree that the concentration of iPB 

likely to be breathed in by workers 

would be below 1 ppm even if workers 

were exposed to concentrations of nPB 

at 100 ppm or more, provided that the 

iPB content meets the ASTM–D6368–00 

standard for nPB used in vapor 

degreasing. Further, even if iPB were 

present in nPB formulations in 

concentrations as high as 1%, if 

industry meets the AEL for nPB 

proposed in 2003 of 25 ppm, or lower, 

exposures still would be at most 0.25 

ppm. This is below the level of 1 ppm 

established by the Korean government 

and by the Japan Society for 

Occupational Health (Morford, 2003h). 

Therefore, we are not adopting a use 

condition for iPB for the solvent 

cleaning end uses. 


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8. Short-Term Exposure Limit (STEL) 

In the June 2003 NPRM, EPA 

recommended a short-term exposure 

limit of 75 ppm (three times the AEL). 

Comment: One commenter noted that 

there was no indication in the various 

applications as to how the exposures 

from those operations compared to the 

EPA recommendation for a STEL at 75 

ppm. This commenter asserted that the 

potential for exceeding the STEL in 

solvent cleaning applications appears 

high and should, therefore, be 

investigated by EPA. This commenter 

also stated that, depending on the 

results of this investigation, EPA may 

choose to find nPB unacceptable in 

metals cleaning or restrict its use to 

where ventilation is employed and/or 

personal protective equipment is worn. 

Response: EPA disagrees that it is 

necessary to use a short-term exposure 

limit in determining the acceptability of 

nPB in solvent cleaning. Acute, shortterm exposures of nPB are not of 

significant health concern, so long as 

long-term exposures are below the 8- 

hour TWA limit (ERG, 2004). EPA 

provided the STEL recommendation in 

the June 2003 proposal to give guidance 

to the user community, consistent with 

the following recommendation of the 

American Conference of Governmental 

Industrial Hygienists (ACGIH): 

‘‘Excursions in worker exposure levels 

may exceed 3 times the [threshold limit 

value] TLV–TWA for no more than a 

total of 30 minutes during a workday’’

(ACGIH 1999). We note that when the 

ACGIH developed a TLV for nPB, they 

said there were no data to support a 

short-term exposure limit (ACGIH, 

2005). 

C. Ozone Depletion Potential 

We proposed that, since the ODP of 

nPB in the continental U.S. is only 

0.013 to 0.018 relative to an ODP of 0.8 

for CFC-113, 0.1 for methyl chloroform, 

and 0.1 for HCFC-141b, nPB should not 

be found unacceptable because of its 

ODP (68 FR 33303). The Agency 

recognized that nPB’s ODP could be 

much higher in tropical regions, as high 

as 0.071 to 0.100, but since EPA is 

regulating nPB used in the U.S., we 

made our decision based on the ODP in 

the continental U.S. 

Comment: One commenter on the 

June 2003 NPRM provided information 

(Wuebbles, 2002) and stated that ‘‘even 

if the entire amount of nPB produced in 

2002 was emitted across North 

American, European and Asian 

latitudes, the resulting effects on ozone 

depletion would be too small to 

measure.’’ The same commenter said 

that the effects on ozone would only be 

larger if all emissions were to occur in 

the equatorial region. (Morford, 2003f). 

Response: EPA agrees that, based on 

the current usage of nPB and its ODP in 

the U.S., there is not a significant 

impact on the ozone layer. 

Comment: Comments on the June 

2003 NPRM expressed concern that 

other countries, particularly those in 

equatorial regions, might assume that 

nPB does not pose a danger to the 

stratospheric ozone layer if the U.S. 

EPA’s SNAP program finds nPB 

acceptable (Linnell, 2003; Steminiski, 

2003). 

Response: Because the ODP for nPB is 

higher when used in the tropics (see 

footnote 3 above in section IV.2), we 

recognize the concerns raised by these 

commenters. However, EPA is 

regulating use in the U.S. and cannot 

dictate actions taken by other countries. 

For example, other countries could 

choose to continue to use nPB even if 

EPA were to find it unacceptable in the 

U.S. We believe the more appropriate 

forum to address this concern is through 

the Parties to the Montreal Protocol. 

At the most recent Meeting of the 

Parties to the Montreal Protocol, the 

Parties made the following decision 

with regard to n-propyl bromide, in 

order to ‘‘allow Parties to consider 

further steps regarding n-propyl 

bromide, in the light of available 

alternatives’’ (Decision XVIII/11): 

1. To request the Scientific 

Assessment Panel to update existing 

information on the ozone depletion 

potential of n-propyl bromide, including 

ozone depleting potential depending on 

the location of the emissions and the 

season in the hemisphere at that 

location; 

2. To request the Technology and 

Economic Assessment Panel to continue 

its assessment of global emissions of npropyl bromide, * * * paying particular 

attention to: 

(a) Obtaining more complete data on 

production and uses of n-propyl 

bromide as well as emissions of npropyl bromide from those sources; 

(b) Providing further information on 

the technological and economical 

availability of alternatives for the 

different use categories of n-propyl 

bromide and information on the toxicity 

of and regulations on the substitutes for 

n-propyl bromide; 

(c) Presenting information on the 

ozone depletion potential of the 

substances for which n-propyl bromide 

is used as a replacement; 

3. To request that the Technology and 

Economic Assessment Panel prepare a 

report on the assessment referred to in 

paragraph 1 in time for the twentyseventh meeting of the Open-ended 

Working Group for the consideration of 

the Nineteenth Meeting of the Parties. 

(MOP 18, 2006) 

D. Other Environmental Impacts 

With respect to environmental effects 

other than ozone depletion potential, we 

stated in the June 2003 NPRM that users 

should observe existing Federal, state, 

and local regulations such as those 

under the Resource Conservation and 

Recovery Act or those for compliance 

with the National Ambient Air Quality 

Standards (68 FR 33304). 

Comment: Commenters stated that, 

until the safety of nPB has been 

demonstrated conclusively, more 

stringent controls are necessary to 

protect the public and the environment. 

In particular, these commenters said 

that the potential for cross-media 

impacts was not given adequate 

consideration in the proposed rule. 

They also stated that EPA did not 

address the potential for nPB to 

bioaccumulate in the environment or its 

impact on sensitive species. One 

commenter said that he thought it was 

appropriate to ensure that nPB be kept 

out of wastewater, and an independent 

contractor also mentioned concerns 

about water pollution. Another 

commenter said that nPB hydrolyzes 

more quickly than the chlorinated 

solvents, and so would have less impact 

on water quality. Currently, the 

representative’s company recommends 

that spent solvents be incinerated, and 

offers free pickup and disposal of spent 

solvent to its customers. 

Response: EPA agrees that it should 

not be standard practice to dispose of 

spent nPB in water, and that nPB should 

be kept out of wastewater to the extent 

possible. This may be achieved by 

recycling or through incineration. These 

also are good practices with other spent 

halogenated solvents, whether or not 

they are specifically listed as hazardous 

wastes. 

EPA’s PBT (persistence/ 

bioaccumulation/toxicity) profiler tool 

suggested that, based on its structure, 

nPB would not be considered persistent 

in water or soil and that nPB would 

have a low tendency to bioaccumulate 

(8.3, where 1000 is considered 

bioaccumulative and greater than 5000 

is considered very bioaccumulative). 

Further, the calculated bioconcentration 

factor for nPB is only in the range of 18 

to 23 (HSDB, 2004; ICF, 2004a). Under 

EPA’s criteria for listing chemicals on 

the Toxics Release Inventory, this 

would not be a level of concern (ICF 

2004a, EPA 1992). Therefore, we 

conclude further testing for 

bioaccumulation of this chemical is not 

needed before rendering a decision for 


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use of nPB in the solvent cleaning 

sector. 

Currently, the estimated amount of 

nPB used in the U.S. in SNAP sectors 

is on the order of 10 to 12 million 

pounds per year, which corresponds to 

roughly 1% of the organic solvent 

cleaning market, a relatively small 

amount. It is unlikely that very large 

amounts of nPB will enter and remain 

in the nation’s water supply, because: 

• nPB tends to evaporate quickly, 

with a calculated half-life of 3.4 hours 

in a river or 4.4 days in a lake due to 

volatilization. 

• nPB hydrolyzes readily, with a 

measured hydrolysis half-life of 26 days 

at 25° C and pH 7. 

• If released to the atmosphere, nPB 

will exist solely in the vapor phase 

based on its vapor pressure of 110.8 mm 

Hg. Thus, it is unlikely to be 

redeposited in rainwater in significant 

amounts. (PBT Profiler, 2007; ICF, 

2004a) 

Further, because nPB is short-lived 

compared to ODS and many ODS 

substitutes, it is unlikely that nPB will 

create a substantially greater impact 

than other acceptable cleaning solvents 

and than the ODS it replaces. EPA is 

required by the Clean Air Act to 

consider whether a replacement for an 

ODS is more harmful, overall, to human 

health and the environment than other 

available or potentially available 

substitutes. The available information 

shows that nPB will not be more 

hazardous than other available, 

acceptable solvents if it pollutes water 

or soil. 

E. Flammability 

In the June 2003 NPRM, we proposed 

that nPB should not be restricted or 

found unacceptable because of 

flammability (68 FR 33303). EPA 

specifically requested data concerning 

the flashpoint of pure nPB, including 

the test method used to provide the 

data. 

Comment: Several manufacturers of 

nPB and nPB-based solvents and an 

independent contractor stated that nPB 

has no flash point under a number of 

accepted consensus standards for flash 

point. In support of these statements, 

the manufacturers of nPB and nPBbased solvents provided flash point test 

data from a number of different test 

methods (ASTM D 92 open cup, ASTM 

D56 Tag closed cup, and ASTM D93 

Pensky-Martens closed cup). 

Response: EPA agrees. The test results 

provided by the commenters indicates 

that nPB has no flash point using a 

number of standard test methods, 

including ASTM D 92 open cup, ASTM 

D56 Tag closed cup, and ASTM D93 

Pensky-Martens closed cup. Based on 

these data, we find that nPB is not 

flammable under standard test 

conditions. EPA concludes that nPB 

should not be considered unacceptable 

on the basis of flammability risks. 

F. Legal Authority to Set Exposure 

Limits 

Comment: Two commenters stated 

that EPA has no jurisdiction to develop 

any AEL designed to be applicable to a 

workplace environment, and that this 

right belongs to OSHA. 

Response: As an initial matter, EPA 

notes that it has not established an AEL 

applicable to the workplace in this rule. 

Rather, EPA reviewed the available 

information to determine what a safe 

workplace exposure might be in order to 

determine whether use of nPB in the 

solvent cleaning sector poses 

substantially more risk than use of other 

available substitutes. The analysis 

performed by EPA imposes no binding 

obligation on anyone, particularly in 

this case where EPA determined that 

nPB is acceptable for use in the solvent 

cleaning sector. 

Although the Occupational Safety and 

Health Act (OSH Act) gives the 

Occupational Safety and Health 

Administration (OSHA) authority to 

issue a rule setting or revising an 

occupational safety or health standard 

(29 U.S.C. 655(b)), it does not prohibit 

other Federal agencies from reviewing 

the safe level of exposure under other 

statutes that require consideration of the 

human health and environmental effects 

of a substance. Conversely, although 

section 4(b)(1) of the OSH Act prohibits 

OSHA from regulating a working 

condition addressed by another federal 

agency’s regulations affecting 

occupational safety or health, this 

provision is overridden with respect to 

EPA’s exercise of authority under the 

Clean Air Act by 42 U.S.C. 7610. That 

provision states: ‘‘(a) Except as provided 

in subsection (b) of this section, this 

chapter shall not be construed as 

superseding or limiting the authorities 

and responsibilities, under any other 

provision of law, of the Administrator or 

any other Federal officer, department, or 

agency.’’

Section 612 of the Clean Air Act 

expressly recognizes that some 

substitutes for ODS may pose more risk 

to human health and the environment 

than others and expressly requires EPA 

to prohibit use of substitutes that pose 

more risk than other substitutes that are 

currently or potentially available. Thus, 

in evaluating whether a substitute 

should be found acceptable, we must 

compare the risks to human health and 

the environment of that substitute to the 

risks associated with other substitutes 

that are currently or potentially 

available. 

Our long-standing interpretation is 

that worker safety is a factor we 

consider in determining whether a 

substitute poses significantly greater 

risk than other available substitutes. In 

the original SNAP rule, we promulgated 

the criteria we would review for 

purposes of determining whether a 

substitute posed more risk than other 

available substitutes. Specifically, 40 

CFR 82.178(a) specifies the information 

we require as part of a SNAP 

application and 40 CFR 82.180(a)(7) 

identifies the criteria for review. 

Notably, we require submitters to 

provide information regarding the 

exposure data (40 CFR 82.178(a)(10)) 

and we identify ‘‘occupational risks’’ as 

one of the criteria for review (40 CFR 

82.180(a)(7)(iv)). In the preamble of the 

original SNAP rule, we said that we 

would use any available OSHA PELs, 

EPA inhalation reference 

concentrations, or EPA cancer slope 

factor data for a substitute together with 

exposure data to explore possible 

concerns with toxicity (March 18, 1994; 

59 FR 13066). We have reviewed 

substitutes based on existing OSHA 

PELs, where available, and, where not 

available, based on our own assessment 

of what level is safe for workers. (See 

e.g., March 18, 1994, 59 FR 13044; Sept. 

5, 1996, 61 FR 47012; June 8, 1999, 64 

FR 30410; June 19, 2000, 65 FR 37900; 

December 18, 2000, 65 FR 78977; March 

22, 2002, 67 FR 13272; August 21, 2003, 

68 FR 50533). In making our own 

assessment, we review any existing 

recommended exposure guidelines and 

available scientific studies and use 

EPA’s risk assessment guidelines (e.g., 

U.S. EPA, 1994b). 

In the case of EPA’s evaluation of 

nPB, there is no final OSHA PEL for 

EPA to use in evaluating workplace 

exposure risks. There is a wide 

variability in the workplace exposure 

guidelines recommended by 

manufacturers of nPB-based products, 

ranging from 5 ppm to 100 ppm, thus 

providing no definitive value for 

evaluating the human health risks of 

workplace exposure. The ACGIH has 

recently established a TLV for nPB of 10 

ppm; however, as discussed above in 

section IV.E, EPA has concerns about 

the scientific basis for this TLV. As 

provided in the original SNAP rule, in 

the absence of a definitive workplace 

exposure limit set by OSHA, we 

evaluated the available information to 

establish our own health-based criteria 

for evaluating nPB’s human health risks 

to workers. 


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Comment: A commenter said that 

EPA’s authority for the SNAP program 

is under section 615 of the Clean Air 

Act and that the SNAP program only 

has authority to take action based on 

effects on the stratosphere. Specifically, 

the commenter claims section 615 of the 

CAA limits EPA’s authority under title 

VI to regulating for purposes of 

protecting the stratospheric ozone layer. 

Citing section 618, the commenter also 

contends that section 618 identified 

SNAP requirements as ‘‘requirements 

for the control and abatement of air 

pollution’’ and cites the CAA and EPA 

policy documents as identifying 

ambient air as air external to buildings. 

The commenter also notes that title VI 

was intended to implement the 

Montreal Protocol and that it replaced 

former Part B. The commenter cites 

legislative history from the enactment of 

Part B that indicated EPA’s authority 

under Part B was not intended to preempt authority of other agencies to take 

action with respect to hazards in their 

areas of jurisdiction and that EPA’s 

authority under Part B was only to fill 

regulatory gaps and not to supersede 

existing authority of other agencies. 

With respect to the legislative history of 

the 1990 Amendments, the commenter 

argues that there is no suggestion that 

‘‘EPA has authority to set workplace 

worker-exposure standards.’’ The 

commenter also cites legislative history 

from the Toxic Substances Control Act 

in which Congress indicated EPA’s 

authority under that statute does not 

extend to setting workplace standards. 

Response: While many provisions in 

title VI address the regulation of 

substances that deplete the stratospheric 

ozone layer, section 612 which governs 

the SNAP program is broader. The 

purpose of Section 612 is to review 

substitutes for ODS and Section 612 of 

the Clean Air Act clearly requires EPA 

to consider both the environmental 

effects as well as human health, which 

includes both the health of the general 

population and workers. EPA believes 

there is no doubt that the statutory 

language requires EPA to consider 

effects beyond those on the 

stratospheric ozone layer. In addition, 

the legislative history makes clear that 

this language is to be interpreted 

broadly. Specifically, the report of 

House Debate on the Clean Air Act 

Amendments provides ‘‘the 

Administrator shall base risk estimates 

on the total environmental risk (toxicity, 

flammability, atmospheric, etc.) that is 

perceived to exist, not just the risk as it 

relates to ozone depletion.’’ House 

Debate on the Clean Air Act 

Amendments of 1990 Conference 

Report, S–Prt 103–38 at 1337. The 

legislative history cited by the 

commenter is not pertinent. The 

legislative history for Part B of Title I of 

the Act is not relevant because that 

section was repealed in 1990. Public 

Law 101–549, section 601. Nor is the 

legislative history for other statutes, 

such as TSCA, relevant for determining 

what authority Congress granted to EPA 

under the CAA. 

The commenter incorrectly states that 

sections 615 and 618 of the CAA place 

limits on EPA’s authority under section 

612 of the Act. These provisions 

expand, rather than restrict, the 

Administrator’s authority. Section 615 

is a separate provision of the statute and 

provides general authority for the 

Administrator to regulate for purposes 

of addressing adverse effects to the 

stratosphere. This provision does not 

explicitly or implicitly purport to limit 

the Administrator’s authority under 

other provisions of the Act. Rather, it is 

a general provision authorizing the 

Administrator to regulate for protecting 

against adverse effects to the 

stratospheric ozone layer. 

With respect to section 618, we first 

note that the commenter appears to 

equate the stratospheric ozone layer 

with ‘‘ambient air.’’ In fact, they are two 

different things. Ambient air is defined 

as ‘‘that portion of the atmosphere, 

external to buildings, to which the 

general public has access.’’ 40 CFR 

50.1(e). The stratospheric level generally 

extends from 10 to 50 kilometers above 

the earth and is not considered air to 

which the public has access. [See 

http://www.epa.gov/ozone/defns.html]. 

The definition of ‘‘air pollutant’’ under 

the CAA is defined in terms of 

substances emitted to the ‘‘ambient air.’’

The purpose of section 618 is to make 

clear that for purposes of sections 116 

(retention of state authority) and 118 

(control of pollution from federal 

facilities), the provisions in Title VI 

governing protection of the stratospheric 

ozone layer shall be treated the same as 

if they were for the purpose of 

controlling and abating ‘‘air pollution’’

(i.e., pollution to the ambient air). 

Again, this is not for the purpose of 

restricting the Administrator’s authority 

under any provision of the Act. Rather, 

it is for the purpose of extending the 

protections of Title VI to programs that 

otherwise only address air pollution 

(i.e., ambient air, which does not 

include the stratospheric ozone layer). 

Comment: A commenter stated that 

EPA’s claim to authority conflicts with 

the Department of Labor’s 

administrative ‘‘whistleblower’’ case 

law. These cases hold that a 

whistleblower action may proceed 

under the CAA only when the 

complaint concerned substances 

emitted to the ambient air. Claims 

regarding air quality within the 

workplace are brought under the 

whistleblower provisions of the OSH 

Act. 

Response: The commenter overstates 

the import of the decisions issued by the 

Administrative Review Board. In each of 

the cited decisions, the Board examined 

the specific circumstances before it to 

determine which statutory 

whistleblower provision provided the 

basis for the claimed action. While 

making general pronouncements that 

the CAA regulates ambient air and 

OSHA regulates air within the 

workplace, none of these opinions 

specifically addressed the scope of 

EPA’s authority under section 612, the 

SNAP provisions of the Act. 

Comment: A commenter stated that 

even if ventilation or other measures 

could reduce exposures to below 25 

ppm, there is nothing to ensure that 

companies will take such measures. 

This commenter also stated that he is 

aware of nPB formulators that have 

already announced they will not adhere 

to this voluntary standard. Three 

commenters, all representing local 

environmental regulators, stated that a 

recommendation that worker exposure 

be limited to 25 ppm will not carry the 

enforcement powers of an OSHA 

standard, and that this lack of control 

will encourage the use of nPB in 

applications beyond those envisioned 

by EPA. Another commenter asserted 

that the proposed exposure limits (both 

the AEL and the STEL) should be 

established as use conditions, citing 

Section 612 as the basis for EPA’s 

authority to do so. This commenter 

stated that a precedent has already been 

set for EPA to accept an alternative 

chemical subject to use conditions—

including that observance of workplace 

concentration limits—in the adhesives, 

aerosols, and solvent cleaning sectors 

(e.g., HCFC–225 ca/cb, HFC–4310mee, 

monochlorotoluenes, benzotrifluorides; 

40 CFR part 82, subpart G, appendices 

A, B, and D). 

Response: EPA agrees that a 

recommended AEL from EPA does not 

provide the same level of protection as 

an enforceable standard from OSHA. We 

also agree that EPA has the authority 

under section 612 to require use 

conditions in those circumstances 

where use of a potentially promising 

substitute would otherwise be 

unacceptable unless those use 

conditions are met and there are 

significant concerns about the ability of 

industry to meet a safe level for use. In 

the preamble to the original SNAP rule, 


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we recognized that there may be cases 

where OSHA has not regulated worker 

exposure to a substitute. We went on to 

say that ‘‘EPA anticipates applying use 

conditions only in the rare instances 

where clear regulatory gaps exist, and 

where an unreasonable risk would exist 

in the absence of any conditions.’’ For 

the solvent cleaning end use, we do not 

believe that there is an unreasonable 

risk in the absence of a use condition. 

Available exposure data show that 

roughly 88% of samples from nPB users 

in solvent cleaning met an exposure 

level of 25 ppm, 81% met an exposure 

level of 18 ppm, and 70% met an 

exposure level of 10 ppm (U.S. EPA, 

2003). One nPB supplier provided 

evidence that on the few occasions 

when nPB concentrations from vapor 

degreasers were higher than the 

company’s recommended AEL of 25 

ppm, users were able to reduce 

exposure easily and inexpensively by 

changing work practices, such as 

reducing drafts near the cleaning 

equipment (Kassem, 2003). Therefore, 

we expect that users of nPB in the 

solvent cleaning sector following typical 

industry practices and using typical 

equipment for vapor degreasing will 

continue to use nPB at levels considered 

safe for workers. As noted above, this is 

the approach we indicated we would 

follow at the time of the original SNAP 

rule and we have taken this same 

approach for many other solvents where 

users are readily able to meet a 

workplace exposure limit that will 

protect human health and there is no 

enforceable OSHA PEL (e.g., HFC–

365mfc and heptafluorocyclopentane at 

65 FR 78977, ketones, alcohols, esters, 

and hydrocarbons at 59 FR 13044). 

Comment: One commenter claims that 

section 6 of the Occupational Safety and 

Health Act requires OSHA to make 

certain legal findings before 

promulgating a standard and that 

therefore EPA has no authority to 

develop any AEL applicable to a 

workplace environment. Furthermore, 

since OSHA is the only agency that can 

make standards applicable in the 

workplace, any level developed by EPA 

is misleading. The same commenter said 

that EPA offers no reasoning as to why 

a different methodology for setting an 

AEL (from that of OSHA) is necessary or 

advisable. Therefore, this commenter 

believes that the Agency’s process 

violates equal protection unless EPA is 

publishing a new standard for chemical 

review under SNAP. 

Response: In this rulemaking, EPA 

has not developed an AEL that is 

applicable in any workplace. Rather, 

EPA looked at a range of possible AELs 

for purposes of determining whether 

nPB will pose significantly greater risk 

than other substitutes that are available 

in the same end use. The range of levels 

EPA used for its analysis is not binding. 

Moreover, as explained above in section 

V.B.2, EPA has concluded that for 

purposes of finding nPB acceptable in 

the solvent cleaning end use, it is not 

necessary to provide a non-binding 

recommended workplace exposure limit 

because these users in the solvent 

cleaning sector are regularly able to 

comply with even the lowest level EPA 

considered in performing its evaluation. 

For standards covering hazardous 

chemicals in the workplace, the OSH 

Act requires OSHA to set standards that, 

to the extent feasible, ensure that 

workers do not suffer material 

impairments of health. Standards 

established by OSHA under their statute 

have not typically prohibited the use of 

the chemical in any particular 

application, but instead establish 

performance goals for the use and 

handling of hazardous chemicals that 

reduce such risks to the extent feasible. 

The available information on health 

effects of nPB on workers is not 

sufficiently well-characterized to 

develop a standard based on avoiding 

material impairments of health in 

workers. Most manufacturers and 

organizations that set workplace 

exposure limits such as ACGIH and the 

American Industrial Hygiene 

Association use an approach similar to 

EPA’s and do not base exposure limits 

on avoiding material impairments of 

health in workers. Because of the need 

for large amounts of well-characterized 

data from the workplace on exposures 

and associated health effects to prepare 

an AEL to prevent material impairment, 

if EPA were to develop AELs for nPB 

and other chemicals based on the 

approach required by section 6 of the 

OSH Act, EPA would effectively be 

unable to assess the human health 

effects of ODS alternatives in time to 

assist industry in transitioning away 

from ODS. In order to provide for a 

more timely assessment of human 

health effects, as well as one that is 

consistent with federal guidelines of the 

National Academies of Science (NAS, 

1983), we have considered exposure 

levels following EPA guidance (U.S. 

EPA, 1994b). Different substances have 

different toxicological effects and those 

effects must be considered based on the 

best scientific information and 

methodologies available. It is incorrect 

to claim that such reviews, which focus 

on the effects of different substances, 

resulted in disparate treatment of nPB. 

VI. How can I use nPB as safely as 

possible? 

Below are actions that will help nPB 

users minimize exposure levels: 

All End Uses 

• All users of nPB should wear 

appropriate personal protective 

equipment, including chemical goggles, 

flexible laminate protective gloves (e.g., 

Viton, Silvershield) and chemicalresistant clothing. Special care should 

be taken to avoid contact with the skin 

since nPB, like many halogenated 

solvents, can be absorbed through the 

skin. Refer to OSHA’s standard for the 

selection and use of Personal Protective 

Equipment, 29 CFR 1910.132. 

• Limit worker exposure to solvents 

to minimize any potential adverse 

health effects. Workers should avoid 

staying for long periods of time in areas 

near where they have been using the 

solvent. Where possible, shorten the 

period during each day when a worker 

is exposed. Where respiratory protection 

is necessary to limit worker exposures, 

respirators must be selected and used in 

accordance with OSHA’s Respiratory 

Protection standard, 29 CFR 1910.134. 

• Use less solvent, or use a different 

solvent, either alone or in a mixture 

with nPB. 

• Follow all recommended safety 

precautions specified in the 

manufacturer’s MSDS. 

• Workers should receive safety 

training and education that includes 

potential health effects of exposure to 

nPB, covering information included on 

the appropriate MSDSs, as required by 

OSHA’s Hazard Communication 

Standard (29 CFR 1910.1200). 

• Request a confidential consultation 

from your State government on all 

aspects of occupational safety and 

health. You can contact the appropriate 

state agency that participates in OSHA’s 

consultation program. These contacts 

are on OSHA’s Web site at http:// 

www.osha.gov/oshdir/consult.html. For 

further information on OSHA’s 

confidential consultancy program, visit 

OSHA’s web page at http:// 

www.osha.gov/html/consultation.html. 

• Use the employee exposure 

monitoring programs and product 

stewardship programs where offered by 

manufacturers and formulators of nPBbased products. 

• If the manufacturer or formulator of 

your nPB-based product does not have 

an exposure monitoring program, we 

recommend that you start your own 

exposure monitoring program, and/or 

request a confidential consultation from 

your State government. A medical 

monitoring program should be 


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established for the early detection and 

prevention of acute and chronic effects 

of exposure to nPB. The workers’

physician(s) should be given 

information about the adverse health 

effects of exposure to nPB and the 

workers’ potential for exposure. 

• For non-aerosol solvent cleaning, 

follow guidelines in the National 

Emissions Standards for Hazardous Air 

Pollutant (NESHAP) for halogenated 

solvents cleaning if you are using nPB. 

The equipment and procedural changes 

described in the halogenated solvents 

NESHAP can reduce emissions, reduce 

solvent losses and lower the cost of 

cleaning with organic solvents. For 

more information on the halogenated 

solvents NESHAP, visit http:// 

www.epa.gov/ttn/atw/eparules.html and 

http://www.epa.gov/ttn/atw/degrea/ 

halopg.html. We note that these steps 

are useful for reducing exposure to any 

industrial solvent, and not just nPB. 

VII. Statutory and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

Under Executive Order (EO) 12866 

(58 FR 51735, October 4, 1993), this 

action is a ‘‘significant regulatory 

action.’’ It raises novel legal or policy 

issues arising out of legal mandates, the 

President’s priorities, or the principles 

set forth in the Executive Order. 

Accordingly, EPA submitted this action 

to the Office of Management and Budget 

(OMB) for review under EO 12866 and 

any changes made in response to OMB 

recommendations have been 

documented in the docket for this 

action. 

In addition, EPA prepared an analysis 

of the potential costs and benefits 

associated with this action. This 

analysis is contained in the document 

‘‘Analysis of Economic Impacts of nPB 

Rulemaking.’’ A copy of the analysis is 

available in the docket for this action 

(Ref. EPA–HQ–OAR–2002–0064) and 

the analysis is briefly summarized here. 

In our analysis, we assumed that 

capital costs are annualized over 15 

years or less using a discount rate for 

determining net present value of 7.0%. 

The acceptability determination for 

solvents cleaning imposes no 

requirements and thus creates no 

additional cost to users. 

EPA also considered potential costs 

end users could incur to meet 

acceptable exposure levels if they are 

not already achieving it. EPA found that 

those users using nPB-based solvents in 

a vapor degreaser would save money by 

reducing solvent losses, and that the 

savings would recover the costs of 

emissions controls (e.g., secondary 

cooling coils, automated lifts or hoists) 

within a year of installation. Based on 

evidence from solvent suppliers, EPA 

believes that some of those users would 

have chosen to use nPB in order to 

avoid meeting requirements of the 

national emission standard for 

halogenated solvents cleaning and that 

they would only become aware of the 

potential savings due to reduced solvent 

usage as a result of this proposal 

(Ultronix, 2001; Kassem, 2003; 

Tattersall, 2004). Based on available 

exposure data for each sector, we 

assumed that 81% of nPB users in the 

non-aerosol solvent cleaning sector 

already achieve exposure levels at the 

lowest level that we considered, i.e., 18 

ppm (U.S. EPA, 2003). Of those nPB 

solvent users with exposure levels 

above that, we examined the cost 

associated with reducing emissions on 

average by 60%. 

If all nPB users in solvent cleaning 

reduced exposures to 18 ppm, EPA 

estimates that users would save up to $2 

million dollars per year, overall (U.S. 

EPA, 2007). The value will depend on 

the number of users that attempt to meet 

an acceptable exposure level which is 

already being achieved with existing 

equipment, the initial exposure level of 

cleaning solvent users, the price of nPB, 

and the amount of emission control 

equipment installed. 

B. Paperwork Reduction Act 

There are no new requirements for 

reporting or recordkeeping or 

information collection associated with 

this final rule. The final rule merely 

allows the use of substitutes for ozonedepleting substances, without requiring 

the collection, keeping, or reporting of 

information. OMB has previously 

approved the information collection 

requirements contained in the existing 

regulations in subpart G of 40 CFR part 

82 under the provisions of the 

Paperwork Reduction Act, 44 U.S.C. 

3501 et seq. and has assigned OMB 

control number 2060–0226 (EPA ICR 

No. 1596.06). This ICR included five 

types of respondent reporting and 

record-keeping activities pursuant to 

SNAP regulations: submission of a 

SNAP petition, filing a SNAP//Toxic 

Substance Control Act (TSCA) 

Addendum, notification for test 

marketing activity, record-keeping for 

substitutes acceptable subject to use 

restrictions, and record-keeping for 

small volume uses. A copy of the OMB 

approved Information Collection 

Request (ICR) may be obtained from 

Susan Auby, Collection Strategies 

Division; U.S. Environmental Protection 

Agency (2822T); 1200 Pennsylvania 

Ave., NW., Washington, DC 20460 or by 

calling (202) 566–1672. 

Burden means the total time, effort, or 

financial resources expended by persons 

to generate, maintain, retain, or disclose 

or provide information to or for a 

Federal agency. This includes the time 

needed to review instructions; develop, 

acquire, install, and utilize technology 

and systems for the purposes of 

collecting, validating, and verifying 

information, processing and 

maintaining information, and disclosing 

and providing information; adjust the 

existing ways to comply with any 

previously applicable instructions and 

requirements; train personnel to be able 

to respond to a collection of 

information; search data sources; 

complete and review the collection of 

information; and transmit or otherwise 

disclose the information. 

An agency may not conduct or 

sponsor, and a person is not required to 

respond to a collection of information 

unless it displays a currently valid OMB 

control number. The OMB control 

numbers for EPA’s regulations in 40 

CFR are listed in 40 CFR part 9. 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act or any 

other statute unless the agency certifies 

that the rule will not have a significant 

economic impact on a substantial 

number of small entities. Small entities 

include small businesses, small 

organizations, and small governmental 

jurisdictions. The RFA provides default 

definitions for each type of small entity. 

Small entities are defined as: (1) A small 

business as defined by the Small 

Business Administration’s (SBA) 

regulations at 13 CFR 121.201; (2) a 

small governmental jurisdiction that is a 

government of a city, county, town, 

school district or special district with a 

population of less than 50,000; and (3) 

a small organization that is any not-forprofit enterprise which is independently 

owned and operated and is not 

dominant in its field. However, the RFA 

also authorizes an agency to use 

alternate definitions for each category of 

small entity, ‘‘which are appropriate to 

the activities of the agency’’ after 

proposing the alternate definition(s) in 

the Federal Register and taking 

comment. 5 U.S.C. 601(3)—(5). In 

addition, to establish an alternate small 

business definition, agencies must 

consult with SBA’s Office of Advocacy. 

For purposes of assessing the impacts 

of EPA’s June 2003 proposed rule on 


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small entities, EPA proposed to define 

‘‘small business’’ as a small business 

with less than 500 employees, rather 

than use the individual SBA size 

standards for the numerous NAICS 

subsectors and codes to simplify the 

economic analysis. We solicited 

comments on the use of this alternate 

definition for this analysis in the June 

2003 NPRM and received no public 

comments. EPA also consulted with the 

SBA’s Office of Advocacy on the use of 

an alternate small business definition of 

500 employees. The Office of Advocacy 

concurred with EPA’s use of this 

alternate definition to analysis the 

economic impacts on small businesses 

from the use of n-propyl bromide as an 

acceptable substitute for use in metals, 

precision, and electronics cleaning, and 

in aerosols and adhesives end-uses. 

Therefore, EPA used this alternate 

definition for this final rule. We believe 

that no small governments or small 

organizations are affected by this rule. 

This approach slightly reduced the 

number of small businesses included in 

our analysis and slightly increased the 

percentage of small businesses for 

whom the analysis indicated the use of 

nPB in metals, precision, and 

electronics cleaning may have an 

economically significant impact. The 

number and types of small businesses 

that are subject to this rule have not 

changed significantly since the June 

2003 proposal. EPA intends to use this 

alternate definition of ‘‘small business’’

for regulatory flexibility analyses under 

the RFA for any other rule related to the 

use of nPB as a chemical alternative to 

ozone-depleting substances (ODS) for 

the same end uses in the June 2003 

NPRM (e.g., adhesives and aerosol 

solvents). 

After considering the economic 

impacts of this rule on small entities, I 

certify that this action will not have a 

significant economic impact on a 

substantial number of small entities. 

EPA estimates that approximately 1470 

users of nPB industrial cleaning 

solvents (e.g., cleaning with vapor 

degreasers) would be subject to this 

rule. This rule lists nPB as an acceptable 

substitute for ODS. This rule itself does 

not impose any binding requirements on 

users of nPB, and therefore will not 

have a significant economic impact on 

a substantial number of small entities. 

EPA did however analyze the potential 

economic impacts on small businesses 

that use nPB for cleaning solvents for 

metals cleaning, electronics cleaning, or 

precision cleaning. The details of EPA’s 

analysis are described in the supporting 

materials for this rulemaking (U.S. EPA, 

2007). Based on its analysis, EPA 

believes businesses using nPB-based 

cleaning solvents for metals cleaning, 

electronics cleaning, or precision 

cleaning would experience significant 

cost benefits by reducing spending on 

solvent. 

D. Unfunded Mandates Reform Act 

Title II of the Unfunded Mandates 

Reform Act of 1995 (UMRA), Public 

Law 104–4, establishes requirements for 

Federal agencies to assess the effects of 

their regulatory actions on State, local, 

and tribal governments and the private 

sector. Under section 202 of the UMRA, 

EPA generally must prepare a written 

statement, including a cost-benefit 

analysis, for proposed and final rules 

with ‘‘Federal mandates’’ that may 

result in expenditures to State, local, 

and tribal governments, in the aggregate, 

or to the private sector, of $100 million 

or more in any one year. Before 

promulgating an EPA rule for which a 

written statement is needed, section 205 

of the UMRA generally requires EPA to 

identify and consider a reasonable 

number of regulatory alternatives and 

adopt the least costly, most costeffective or least burdensome alternative 

that achieves the objectives of the rule. 

The provisions of section 205 do not 

apply when they are inconsistent with 

applicable law. Moreover, section 205 

allows EPA to adopt an alternative other 

than the least costly, most cost-effective 

or least burdensome alternative if the 

Administrator publishes with the final 

rule an explanation why that alternative 

was not adopted. Before EPA establishes 

any regulatory requirements that may 

significantly or uniquely affect small 

governments, including tribal 

governments, it must have developed 

under section 203 of the UMRA a small 

government agency plan. The plan must 

provide for notifying potentially 

affected small governments, enabling 

officials of affected small governments 

to have meaningful and timely input in 

the development of EPA regulatory 

proposals with significant Federal 

intergovernmental mandates, and 

informing, educating, and advising 

small governments on compliance with 

the regulatory requirements. EPA has 

determined that this rule does not 

contain a Federal mandate that may 

result in expenditures of $100 million or 

more for State, local, and tribal 

governments, in the aggregate, or the 

private sector in any one year. This final 

rule does not affect State, local, or tribal 

governments. This rule contains no 

enforceable requirements. The impact of 

users meeting the AEL range discussed 

in the preamble is from a savings of $2 

million per year to a cost of $0 million 

per year. Therefore, the impact of this 

rule on the private sector is less than 

$100 million per year. Thus, this rule is 

not subject to the requirements of 

sections 202 and 205 of the UMRA. EPA 

has determined that this rule contains 

no regulatory requirements that might 

significantly or uniquely affect small 

governments. This regulation applies 

directly to facilities that use these 

substances and not to governmental 

entities. 

E. Executive Order 13132: Federalism 

Executive Order 13132, entitled 

‘‘Federalism’’ (64 FR 43255, August 10, 

1999), requires EPA to develop an 

accountable process to ensure 

‘‘meaningful and timely input by State 

and local officials in the development of 

regulatory policies that have federalism 

implications.’’ ‘‘Policies that have 

federalism implications’’ is defined in 

the Executive Order to include 

regulations that have ‘‘substantial direct 

effects on the States, on the relationship 

between the national government and 

the States, or on the distribution of 

power and responsibilities among the 

various levels of government.’’

This final rule does not have 

federalism implications. It will not have 

substantial direct effects on the States, 

on the relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in 

Executive Order 13132. This regulation 

applies directly to facilities that use 

these substances and not to 

governmental entities. Thus, Executive 

Order 13132 does not apply to this rule. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

Executive Order 13175, entitled 

‘‘Consultation and Coordination with 

Indian Tribal Governments’’ (65 FR 

67249, November 6, 2000), requires EPA 

to develop an accountable process to 

ensure ‘‘meaningful and timely input by 

tribal officials in the development of 

regulatory policies that have tribal 

implications.’’ ‘‘Policies that have tribal 

implications’’ is defined in the 

Executive Order to include regulations 

that have ‘‘substantial direct effects on 

one or more Indian tribes, on the 

relationship between the Federal 

government and the Indian tribes, or on 

the distribution of power and 

responsibilities between the Federal 

government and Indian tribes.’’

This final rule does not have tribal 

implications. It will not have substantial 

direct effects on tribal governments, on 

the relationship between the Federal 

government and Indian tribes, or on the 


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distribution of power and 

responsibilities between the Federal 

government and Indian tribes, as 

specified in Executive Order 13175. 

This final rule would not significantly 

or uniquely affect the communities of 

Indian tribal governments, because this 

regulation applies directly to facilities 

that use these substances and not to 

governmental entities. Thus, Executive 

Order 13175 does not apply to this final 

rule. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

and Safety Risks 

Executive Order 13045: ‘‘Protection of 

Children from Environmental Health 

Risks and Safety Risks’’ (62 FR 19885, 

April 23, 1997) applies to any rule that: 

(1) Is determined to be ‘‘economically 

significant’’ as defined under Executive 

Order 12866, and (2) concerns an 

environmental health or safety risk that 

EPA has reason to believe may have a 

disproportionate effect on children. If 

the regulatory action meets both criteria, 

the Agency must evaluate the 

environmental health or safety effects of 

the planned rule on children, and 

explain why the planned regulation is 

preferable to other potentially effective 

and reasonably feasible alternatives 

considered by the Agency. 

This final rule is not subject to the 

Executive Order because it is not 

economically significant as defined in 

Executive Order 12866, and because the 

Agency does not have reason to believe 

the environmental health or safety risks 

addressed by this action present a 

disproportionate risk to children. The 

exposure limits and acceptability 

listings in this final rule apply to the 

workplace. These are areas where we 

expect adults are more likely to be 

present than children, and thus, the 

agents do not put children at risk 

disproportionately. 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This rule is not a ‘‘significant energy 

action’’ as defined in Executive Order 

13211, ‘‘Actions Concerning Regulations 

That Significantly Affect Energy Supply, 

Distribution, or Use’’ (66 FR 28355 (May 

22, 2001)) because it is not likely to 

have a significant adverse effect on the 

supply, distribution, or use of energy. 

This action would impact 

manufacturing of various metal, 

electronic, medical, and optical 

products cleaned with solvents 

containing nPB and products made with 

adhesives containing nPB. Further, we 

have concluded that this rule is not 

likely to have any adverse energy 

effects. 

I. National Technology Transfer and 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (‘‘NTTAA’’), Public Law 

104–113, section 12(d) (15 U.S.C. 272 

note) directs EPA to use voluntary 

consensus standards in its regulatory 

activities unless to do so would be 

inconsistent with applicable law or 

otherwise impractical. Voluntary 

consensus standards are technical 

standards (e.g., materials specifications, 

test methods, sampling procedures, and 

business practices) that are developed or 

adopted by voluntary consensus 

standards bodies. The NTTAA directs 

EPA to provide Congress, through OMB, 

explanations when the Agency decides 

not to use available and applicable 

voluntary consensus standards. 

This action does not involve technical 

standards. Therefore, EPA did not 

consider the use of any voluntary 

consensus standards. 

J. Congressional Review Act 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this rule and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). This rule 

will be effective July 30, 2007. 

VIII. References 

The documents below are referenced 

in the preamble. All documents are 

located in the Air Docket at the address 

listed in section I.B.1 at the beginning 

of this document. Unless specified 

otherwise, all documents are available 

electronically through the Federal 

Docket Management System, Docket # 

EPA–HQ–OAR–2002–0064. Some 

specific items are available only in hard 

copy in dockets A–2001–07 or A–92–42 

(legacy docket numbers for SNAP nPB 

rule and for SNAP program and 

submissions). Numbers listed after the 

reference indicate the docket and item 

numbers. 

Availability 

IBSA, 2002. Record of September 5, 2002 

Meeting with the International 

Brominated Solvents Association Inc. 

(A–2001–07, II–D–60) 

Ozone-Depletion Potential and Other 

Environmental Impacts 

ATSDR, 1994. Toxicological Profile For 

Acetone. Agency for Toxic Substances 

and Disease Registry. May, 1994. 

Available at http://www.atsdr.cdc.gov/ 

toxprofiles/tp21-c5.pdf (EPA–HQ–OAR–

2002–0064–0118) 

ATSDR, 1996. Toxicological Profile For 1,2- 

Dichloroethene. Agency for Toxic 

Substances and Disease Registry. August, 

1996. Available at http:// 

www.atsdr.cdc.gov/toxprofiles/tp87- 

c5.pdf (EPA–HQ–OAR–2002–0064–

0113) 

ATSDR, 1997. Toxicological Profile For 

Trichloroethylene. Agency for Toxic 

Substances and Disease Registry. 

September, 1997. Available at http:// 

www.atsdr.cdc.gov/toxprofiles/tp19- 

c5.pdf (EPA–HQ–OAR–2002–0064–

0123) 

ATSDR, 2004. Draft Toxicological Profile For 

1,1,1-Trichloroethane. Agency for Toxic 

Substances and Disease Registry. 

September, 2004. Updated draft for 

comment. Available at http:// 

www.atsdr.cdc.gov/toxprofiles/tp70- 

c6.pdf (EPA–HQ–OAR–2002–0064–

0132) 

EDSTAC, 1998. Final Report of the Endocrine 

Disruptor Screening and Testing 

Advisory Committee. August, 1998. 

(EPA–HQ–OAR–2002–0064–0136) 

Geiger et al., 1998. Geiger, D.L., Call, D.J., 

and Brooke, L.T. 1988. Acute Toxicities 

of Organic Chemicals to Fathead 

Minnows (Pimephales promelas), Vol. 4. 

In: Center for Lake Superior 

Environmental Stud., Univ. of 

Wisconsin-Superior, Superior, WI I:355. 

(Summarized in ICF, 2004a) 

HSDB, 2004. Hazardous Substances Databank 

File for 1-Bromopropane. Accessed 1/ 

2004 from the World Wide Web at http:// 

toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./ 

temp/∼dLwM9e:1 (Summarized in ICF, 

2004a) 

ICF, 2004a. ICF Consulting. Memo to E. 

Birgfeld, EPA, re: nPB Aquatic Toxicity. 

January 19, 2004. (EPA–HQ–OAR–2002–

0064–0193) 

LaGrega, M., Buckingham, P., Evans, J., and 

Environmental Resources Management, 

2001. Hazardous Waste Management. 

Second Edition. McGraw-Hill, New 

York, NY. 2001. (EPA–HQ–OAR–2002–

0064–0112) 

Linnell, 2003. Comments from the 

Electronics Industry Alliance. (EPA–HQ–

OAR–2002–0064 items –0043, –0044, 

and –0045) 

NPS, 1997. Irwin, R.J., M. VanMouwerik, L. 

Stevens, M.S. Seese, and W. Basham. 

1997. Environmental Contaminants 

Encyclopedia. National Park Service, 

Water Resources Division, Fort Collins, 

Colorado. (EPA–HQ–OAR–2002–0064–

0086) 


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Steminiski, 2003. July 27, 2003 Comment 

from J. Steminiski, PhD. (EPA–HQ–

OAR–2002–0064–0035 and –0043) 

U.S. Economic Census, 2002a. General 

Summary: 2002. Subject Series. Report 

No. EC02–31SG–1, October, 2005. U.S. 

Census Bureau. (EPA–HQ–OAR–2002–

0064–0133) 

U.S. Economic Census, 2002b. U.S. Economic 

Census for Island Areas, 2002. Report for 

Northern Marianas Islands, Rpt. No. 

IA02–00A–NMI, May, 2004. U.S. Census 

Bureau. (EPA–HQ–OAR–2002–0064–

0091) 

U.S. Economic Census, 2002c. U.S. Economic 

Census for Island Areas, 2002. Report for 

Guam, Rpt. No. IA02–00A–GUAM, 

March, 2005. U.S. Census Bureau. (EPA–

HQ–OAR–2002–0064–0102) 

U.S. Economic Census, 2002d. U.S. 

Economic Census for Island Areas, 2002. 

Report for Virgin Islands, Rpt. No. IA02–

00A–VI , April, 2005. U.S. Census 

Bureau. (EPA–HQ–OAR–2002–0064–

0131) 

U.S. Economic Census, 2002e. U.S. Economic 

Census for Island Areas, 2002. Report for 

American Samoa, Rpt. No. IA02–00A–

AS, April, 2005. U.S. Census Bureau. 

(EPA–HQ–OAR–2002–0064–0103) 

U.S. Economic Census, 2002f. U.S. Economic 

Census for Island Areas, 2002. Report for 

Puerto Rico: Manufacturing, Rpt. No. 

IA02–00I–PRM, October, 2005. U.S. 

Census Bureau. (EPA–HQ–OAR–2002–

0064–0107) 

U.S. EPA, 1980. Ambient Water Quality 

Criteria for Dichloroethylenes. EPA 440/ 

5–80–041 October, 1980. Available at 

http://www.epa.gov/waterscience/pc/ 

ambientwqc/dichloroethylenes80.pdf 

U.S. EPA, 1992. Hazard Assessment 

Guidelines for Listing Chemicals on the 

Toxic Release Inventory, Revised Draft. 

Washington, DC: Office of Pollution, 

Prevention and Toxics. As referenced in 

ICF, 2004a. 

U.S. EPA, 1994a. Chemical Summary for 

Methyl Chloroform, prepared by Office 

of Pollution Prevention and Toxics, 

August, 1994. (EPA–HQ–OAR–2002–

0064–0121) 

WMO, 2002: Scientific Assessment of Ozone 

Depletion: 2002, Global Ozone Research 

and Monitoring Project—Report No. 47, 

Geneva, 2003 Full report available online 

at http://esrl.noaa.gov/csd/assessments/ 

(A–2001–07, II–A–20) 

Wuebbles, Donald J. 2002. ‘‘The Effect of 

Short Atmospheric Lifetimes on 

Stratospheric Ozone.’’ Written for Enviro 

Tech International, Inc. Department of 

Atmospheric Sciences, University of 

Illinois-Urbana. (EPA–HQ–OAR–2002–

0064–0114) 

Flammability and Fire Safety 

BSOC, 2000. February 1, 2000 Tabulation of 

Flammability Studies on n-Propyl 

Bromide from the Brominated Solvents 

Committee, and other information on 

flammability of n-propyl bromide. (A–

2001–07, II–D–45) 

Miller, 2003. Albemarle Corporation 

comments-Flash Point Data for n-Propyl 

Bromide. (EPA–HQ–OAR–2002–0064–

0040) 

Morford, 2003a, b. Enviro Tech International 

Comment re Section IV D Flammability 

with Exhibits (7/25/03) (EPA–HQ–OAR–

2002–0064–0030 and EPA–HQ–OAR–

2002–0064–0031) 

Morford, 2003c. Enviro Tech Int. 

Flammability of nPB & Comparison With 

Methylene Chloride-Additional 

Comments on Flammability (7/29/03) 

(EPA–HQ–OAR–2002–0064–0036) 

Shubkin, 2003. R. Shubkin, Poly Systems, 

EPA received 7/23/03 Re: Comment on 

Flammability of n-Propyl Bromide as 

Discussed in Proposed Rule Published in 

Federal Register (EPA–HQ–OAR–2002–

0064–0025) 

Weiss Cohen, 2003. T. Weiss Cohen, Dead 

Sea Bromine Group, 7/31/2003 Comment 

to Federal Register Proposed Rules of 

June 3, 2003, on Protection of 

Stratospheric Ozone: Listing of 

Substitutes for Ozone-Depleting 

Substances—n-Propyl Bromide (EPA–

HQ–OAR–2002–0064–0053) 

Human Health 

ACGIH, 1991. Skin Notation Documentation 

for Methyl Chloride. Available online at 

http://www.acgih.org. 

ACGIH, 2005. Documentation for Threshold 

Limit Value for 1-Bromopropane. 2005. 

Available online at http://www.acgih.org. 

Albemarle, 2003. Product Description for 

Abzol() Cleaners. 2003. (EPA–HQ–

OAR–2002–0064–0148) 

Beck and Caravati, 2003. Neurotoxicity 

associated with 1-bromopropane 

exposure. Utah Poison Control Center, 

University of Utah, Salt Lake City, UT. 

J Toxicology Clinical Toxicology 

41(5):729. (Abstract from conference). 

2003. (EPA–HQ–OAR–2002–0064–0111) 

CERHR, 2002a. NTP-Center for the 

Evaluation of Risks to Human 

Reproduction Expert Panel Report on the 

Reproductive and Developmental 

Toxicity of 1–Bromopropane [nPB]. 

March 2002. (EPA–HQ–OAR–2002–

0064–0096) 

ClinTrials, 1997a. A 28-Day Inhalation Study 

of a VaporFormulation of ALBTA1 in the 

Albino Rat. Report No. 91189. Prepared 

by ClinTrials BioResearch Laboratories, 

Ltd., Senneville, Quebec, Canada. May 

15, 1997. Sponsored by Albemarle 

Corporation, Baton Rouge, LA. (A–91–

42, X–A–4) 

ClinTrials, 1997b. ALBTA1: A 13–Week 

Inhalation Study of a Vapor Formulation 

of ALBTA1 in the Albino Rat. Report No. 

91190. Prepared by ClinTrials 

BioResearch Laboratories, Ltd., 

Senneville, Quebec, Canada. February 

28, 1997. Sponsored by Albemarle 

Corporation, Baton Rouge, LA. (A–91–

42, X–A–5) 

Dunson et al, 2002. Dunson, D., Colombo, 

and B., Baird, D. Changes with age in the 

level and duration of fertility in the 

menstrual cycle. Human Reproduction, 

Vol. 17, No. 5, pp. 1399–1403, 2002. 

(EPA–HQ–OAR–2002–0064–0120) 

Fueta et al., 2002. Y. Fueta, K. Fukunaga, T. 

Ishidao, H. Hori. Hyperexcitability and 

changes in activities of Ca2+/ 

calmodulin-dependent kinase II and 

mitogen-activated protein kinase in the 

hippocampus of rats exposed to 1- 

bromopropane. 2002. Life Sciences 72 

(2002) 521–529. (EPA–HQ–OAR–2002–

0064–0115) 

Fueta et al., 2004. Y. Fueta, T. Fukuda, T. 

Ishidao, H. Hori. Electrophysiology and 

immunohistochemistry in the 

hippocampal CA1 and the Dentate Gyrus 

of Rats Chronically exposed to 1–

Bromopropane, a Substitute for Specific 

Chlorofluorocarbons. Neuroscience 124 

(2004) 593–603. (EPA–HQ–OAR–2002–

0064–0142) 

Honma et al., 2003. Honma, T, Suda M, 

Miyagawa M. ‘‘Inhalation of 1- 

bromopropane causes excitation in the 

central nervous system of male F344 

rats.’’ Neurotoxicology. 2003 Aug; 24 (4–

5):563–75. (EPA–HQ–OAR–2002–0064–

0138) 

ICF, 2002. Risk Screen for Use of N-Propyl 

Bromide. ICF Consulting. Prepared for 

U.S. EPA, May, 2002. (EPA–HQ–OAR–

2002–0064–0006 through –0012) 

ICF, 2004b. ICF Consulting. ICF Consulting 

Review of the TERA Report. December 

13, 2004 

ICF, 2004c. ICF Consulting. External Expert 

Review Panel on n-Propyl Bromide. 

December 13, 2004 

ICF, 2004d. ICF Consulting. Review of 

ACGIH’s Proposed Threshold Limit 

Value for 1-Bromopropane. April 26, 

2004 

ICF, 2006a. ICF Consulting. Risk Screen on 

Substitutes for Ozone-Depleting 

Substances for Adhesive, Aerosol 

Solvent, and Solvent Cleaning 

Applications. Proposed Substitute: nPropyl Bromide. April 18, 2006. 

Attachments: A, Determination of an 

AEL; B, Derivation of an RfC; C, 

Evaluation of the Global Warming 

Potential; D, Occupational Exposure 

Analysis for Adhesive Applications; E, 

Occupational Exposure Analysis for 

Aerosol Solvent Applications; F, General 

Population Exposure Assessment for nPropyl Bromide 

ICF, 2006b. ICF Consulting. Revised 

Memorandum regarding RTI Metabolism 

Study on nPB. April, 2006. (EPA–HQ–

OAR–2002–0064–0179) 

Ichihara G., Jong X., Onizuka J., et al., 1999. 

Histopathological changes of nervous 

system and reproductive organ and 

blood biochemical findings in rats 

exposed to 1-bromopropane. (Abstract 

only) Abstracts of the 72nd Annual 

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(A–2001–07, II–A–15) 

Ichihara G., Kitoh J., Yu, X., et al., 2000a. 1- 

Bromopropane, an alternative to ozone 

layer depleting solvents, is dosedependently neurotoxic to rats in longterm inhalation exposure. Toxicol 

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Ichihara G., Yu X., Kitoh J., et al. 2000b. 

Reproductive toxicity of 1- 

bromopropane, a newly introduced 

alternative to ozone layer depleting 

solvents, in male rats. Toxicol Sciences 

54:416–423. (A–2001–07, II–A–7) 


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Ichihara G. et al., 2002. Neurological 

Disorders in Three Workers Exposed to 

1–Bromopropane. J Occu. Health 44:1–7. 

(A–2001–07, II–D–64) 

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Ding, S. Peng, X. Yu, E. Shibata, T. 

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Takeuchi. A Survey on Exposure Level, 

Health Status, and Biomarkers in 

Workers Exposed to 1-Bromopropane. 

Am Jrnl of Ind Med 45:63–75 (2004) 

(EPA–HQ–OAR–2002–0064–0093) 

Ichihara et al., 2004b. Gaku Ichihara, Weihua 

Li, Eiji Shibata, Xuncheng Ding, Hailan 

Wang, Yideng Liang, Simeng Peng, 

Seiichiro Itohara, Michihiro Kamijima, 

Qiyuan Fan, Yunhui Zhang, Enhong 

Zhong, Xiaoyun Wu, William M. 

Valentine, and Yasuhiro Takeuchi. 

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of 1-Bromopropane Factory. Env’l Health 

Perspectives, 30 June 2004. (EPA–HQ–

OAR–2002–0064–0139) 

Ishidao et al., 2002. Ishidao T, Kunugita N, 

Fueta Y, Arashidani K, Hori H. Effects of 

inhaled 1-bromopropane vapor on rat 

metabolism. Toxicol Lett. 2002 Aug 5; 

134(1–3):237–43 (EPA–HQ–OAR–2002–

0064–0125) 

Majersik et al., 2004. Chronic Exposure to 1- 

Bromopropane Associated with Spastic 

Paraparesis and Distal Neuropathy: A 

Report of Six Foam Cushion Gluers. 

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(EPA–HQ–OAR–2002–0064–0219) 

Majersik et al, 2005. ‘‘Spastic Paraparesis and 

Distal Neuropathy Associated with 

Chronic Exposure to 1BP,’’ Presentation 

by Drs. J. Majersik, M. Caravati, and J. 

Steffens at the North American Congress 

of Clinical Toxicologists. September 14, 

2005. (EPA–HQ–OAR–2002–0064–0116) 

Miller, 2005. ‘‘1-Bromopropane: A Private 

Neurological Practice Experience in 

2000,’’ Presentation by Dr. J.M. Miller, at 

the North American Congress of Clinical 

Toxicologists. September 14, 2005 (EPA–

HQ–OAR–2002–0064–0216) 

Nemhauser, 2005. ‘‘Bromopropane: A Health 

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NIOSH, 2003a. NIOSH Health Hazard 

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NTP, 2003. Results of 13-week Inhalation 

Testing by the National Toxicology 

Program. Available at http://ntpapps.niehs.nih.gov/ntp_tox/

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Toxicology Advisor, Albemarle 

Corporation to The Science Group of the 

American Conference of Governmental 

Industrial Hygienists. Comments on the 

draft Documentation for proposed TLV 

for 1-bropmopropane (1-BP). July 30, 

2004. (EPA–HQ–OAR–2002–0064–0128) 

Raymond and Ford, 2005. ‘‘Clinical Case 

Presentations from a Foam Furniture 

Fabrication Plant in North Carolina,’’

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Marsha Ford at the North American 

Congress of Clinical Toxicologists. 

September 14, 2005. (EPA–HQ–OAR–

2002–0064–0170) 

Risotto, 2003. Comments of the Halogenated 

Solvents Industry Alliance on nPB 

proposed rule. June, 2003. (EPA–HQ–

OAR–2002–0064–0050) 

Rodricks, 2002. October 21, 2002 remarks 

from Dr. J. Rodricks, Environ, to R. 

Morford, Enviro Tech International 

concerning derivation of an OEL for npropyl bromide with cover letter to EPA 

from Enviro Tech International (A–2001–

07, II–D–65) 

Rozman and Doull, 2002. ‘‘Derivation of an 

Occupational Exposure Limit for nPropyl Bromide Using an Improved 

Methodology’’ App Occu. Env. Hyg. 17: 

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Rozman and Doull, 2005. Presentation by 

Drs. Rozman and Doull at the North 

American Congress of Clinical 

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(EPA–HQ–OAR–2002–0064–0126) 

RTI, 2005. Report on uptake and metabolism 

of 1-bromopropane in rats and mice. 

Research Triangle Institute report for the 

National Toxicology Program. June, 

2005. (EPA–HQ–OAR–2002–0064–0077, 

–0080, –0081, –0082, –0101, –0104, 

–0137, –0137.1) 

Sekiguchi, S., Suda, M., Zhai, Y.L., Honma, 

T., ‘‘Effects of 1-bromopropane, 2- 

bromopropane, and 1,2-dichloropropane 

on the estrous cycle and ovulation in 

F344 rats.’’ Toxicol Lett 2002 Jan 5; 

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Occupational Exposure Limit for nPropyl Bromide.’’ Prepared for Enviro 

Tech International, Inc. 2001. (A–2001–

07, II–D–15) 

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J.W., Seo, H.H., Kim, J.Y., Kim, H.Y., Lee, 

J.Y., Lee, S.B., Han, J.H., Lee, Y.M., Lee, 

J.Y. ‘‘A histopathologic study of the 

nervous system after inhalation exposure 

of 1-bromopropane in rat.’’ Toxicol Lett. 

2002 May 28; 131(3):195–201. (EPA–

HQ–OAR–2002–0064–0127) 

Stelljes and Wood, 2004. Stelljes, M., Wood, 

R. Development of an occupational 

exposure limit for n-propylbromide 

using benchmark dose methods. 

Regulatory Toxicology and 

Pharmacology 40 (2004) 136–150 (EPA–

HQ–OAR–2002–0064–0087) 

Stelljes, ME, 2005. Mechanistic Hypothesis 

for n-Propylbromide and Ramifications 

for Occupational Exposure Limit in the 

United States. Technical Memorandum 

to EnviroTech International. 7 

September, 2005. (EPA–HQ–OAR–2002–

0064–0144) 

TERA, 2004. Toxicological Excellence for 

Risk Assessment. Scientific Review of 1- 

Bromopropane Occupational Exposure 

Limit Derivations—Preliminary 

Thoughts and Areas for Further 

Analysis. 2004. (EPA–HQ–OAR–2002–

0064–0189) 

Toraason, M., Lynch, D.W., DeBorda, D.G., 

Singh, N., Krieg, E., Butler, 

M.A.,Toennis, C.A., Nemhauser, J.B., 

2006. DNA damage in leukocytes of 

workers occupationally exposed to 1- 

bromopropane. Mutation Research 603 

(2006) 1–14 (EPA–HQ–OAR–2002–0064–

0130) 

U.S. EPA, 1991. Guidelines for 

Developmental Toxicity Risk 

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Protection Agency. (A–2001–07, II–A–

51) 

U.S. EPA, 1994b. U.S. Environmental 

Protection Agency (U.S. EPA). 1994. 

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reference concentrations and application 

of inhalation dosimetry. EPA/600/8–90/ 

066F. Office of Health and 

Environmental Assessment, Washington, 

DC. 1994. (A–2001–07, II–A–16) 

Available online at http://cfpub.epa.gov/ 

ncea/cfm/recordisplay.cfm?deid=71993 

U.S. EPA, 1995b. The Use of the Benchmark 

Dose Approach in Health Risk 

Assessment. EPA/630–R–94–007. Risk 

Assessment Forum, Washington, DC. (A–

2001–07, II–A–17) 

U.S. EPA, 1996. Guidelines for Reproductive 

Toxicity Risk Assessment. U.S. 

Environmental Protection Agency, Risk 

Assessment Forum, Washington, DC, 

630/R–96/009, 1996. (EPA–HQ–OAR–

2002–0064–0109) 

U.S. EPA, 2003. Summary of Data on 

Workplace Exposure to n-Propyl 

Bromide, May 21, 2003. EPA’s summary 

of exposure data from nPB suppliers and 

NIOSH. (EPA–HQ–OAR–2002–0064–

0015 and EPA–HQ–OAR–2002–0064–

0016). 

Wang et al., 2003. H. Wang, G. Ichihara, H. 

Ito, K. Kato, J. Kitoh, T. Yamada, X. Yu, 

S. Tsuboi, Y. Moriyama, and Y. 

Takeuchi. 2003. ‘‘Dose-Dependant 

Biochemical Changes in RateCentral 

Nervous System after 12-Week Exposure 

to 1-Bromopropane’’ NeuroToxicology 

24: 199–206 (EPA–HQ–OAR–2002–

0064–0088) 

Werner, 2003. Comments from 3M on nPB 

proposed rule. (EPA–HQ–OAR–2002–

0064–0058). 

WIL, 2001. WIL Research Laboratories. ‘‘An 

inhalation two-generation reproductive 

toxicity study of 1-bromopropane in 

rats.’’ Sponsored by the Brominated 

Solvent Consortium. May 24, 2001. 

(A–2001–07, II–D–10) 

Yamada T. et al., 2003. Exposure to 

1-Bromopropane Causes Ovarian 

Dysfunction in Rats. Toxicol Sci 71:96–

103 (EPA–HQ–OAR–2002–0064–0097) 

How Is EPA Responding to Comments? 

ACGIH, 1991. Full citation above in ‘‘Human 

Health’’ section. 

ACGIH, 2004. TLVs and BEIs: Threshold 

Limit Values for Chemical Substances 

and Physical Agents, Biological 

Exposure Indices. American Conference 

of Governmental Industrial Hygienists. 


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30166 Federal Register / Vol. 72, No. 103 / Wednesday, May 30, 2007 / Rules and Regulations 

Cincinnati, OH. Available online at 

http://www.acgih.org. 

ACGIH, 2005. Full citation above in ‘‘Human 

Health’’ section. 

Beck and Caravati, 2003. Full citation above 

in ‘‘Human Health’’ section. 

Chemtura, 2006. Material Safety Data Sheet 

for n-propyl bromide. April, 2006. (EPA–

HQ–OAR–2002–0064–0151) 

ClinTrials, 1997a. Full citation above in 

‘‘Human Health’’ section. 

ClinTrials, 1997b. Full citation above in 

‘‘Human Health’’ section. 

Doull and Rozman, 2001. Doull and Rozman, 

2001. Derivation of an Occupational 

Exposure Limit for n-Propyl Bromide, 

prepared by John Doull, Ph.D., M.D., and 

Karl K. Rozman, Ph.D., D.A.B.T. 

submitted by Envirotech International, 

Inc. (A–2001–07, II–D–14) 

Dunson et al., 2002. Full citation above in 

‘‘Human Health’’ section. 

Elf Atochem, 1995. Elf Atochem, 1995. 

Micronucleus Test by Intraperitoneal 

Route in Mice. n-Propyl Bromide. Study 

No. 12122 MAS. Study Director, Brigitte 

Molinier. Study performed by Centre 

International de Toxoicologie, Misery, 

France, September 6, 1995. (A–91–42, 

X–A–9) 

ERG, 2004. Analysis of Health and 

Environmental Impacts of ODS 

Substitutes—Evaluating the need to set a 

short-term exposure or ceiling limit for 

n-propyl bromide. ERG. June 8, 2004. 

Farr, 2003. Comment on proposed rule on npropyl bromide from Craig Farr, Atofina. 

July 31, 2003. (EPA–HQ–OAR–2002–

0064–0060) 

HDSB, 2004. Full citation above in ‘‘OzoneDepletion Potential and Other 

Environmental Impacts’’ section. 

HESIS, 2003. California Department of Health 

Services—HESIS 1-Bromopropane 

(n-Propyl Bromide) Health Hazard Alert. 

(EPA–HQ–OAR–2002–0064–0039) 

Honma, 2003. Full citation above in ‘‘Human 

Health’’ section. 

ICF, 2002a. Full citation above in ‘‘Human 

Health’’ section. 

ICF, 2004a. Full citation above in ‘‘OzoneDepletion Potential and Other 

Environmental Impacts’’ section. 

ICF, 2006a. Full citation above in ‘‘Human 

Health’’ section. 

ICF, 2006b. Full citation above in ‘‘Human 

Health’’ section. 

ICF, 2006c. ICF Consulting. Evaluation of 

Memorandum from Dr. M. Stelljes. May, 

2006. 

Ichihara, 1999. Full citation above in 

‘‘Human Health’’ section. 

Ichihara, 2000a. Full citation above in 

‘‘Human Health’’ section. 

Ichihara, 2002. Full citation above in 

‘‘Human Health’’ section. 

Ichihara, 2004a. Full citation above in 

‘‘Human Health’’ section. 

Ichihara, 2004b. Full citation above in 

‘‘Human Health’’ section. 

Kassem, 2003. January 10, 2003 Letter from 

O.M. Kassem, Albemarle Corporation to 

K. Bromberg, Small Business 

Administration Re: n propyl bromide 

SNAP. (A–2001–07, II–D–78) 

Linnell, 2003. Full citation above in ‘‘OzoneDepletion Potential and Other 

Environmental Impacts’’ section. 

Majersik, 2004. Full citation above in 

‘‘Human Health’’ section. 

Majersik, 2005. Full citation above in 

‘‘Human Health’’ section. 

MOP 18, 2006. Report of the Eighteenth 

Meeting of the Parties to the Montreal 

Protocol on Substances that Deplete the 

Ozone Layer. November 16, 2006. (EPAHQ–OAR–2002–0064–0163) 

Morford, 2003a. Full citation above in 

‘‘Flammability’’ section. 

Morford, 2003b. Full citation above in 

‘‘Flammability’’ section. 

Morford, 2003c. Full citation above in 

‘‘Flammability’’ section. 

Morford, 2003d. Support for EPA Proposal to 

Approve n propyl bromide and 

Comments Pursuant to Section D. 

Flammability of Protection of 

Stratospheric Ozone: Listing of 

Substitutes for Ozone Depleting 

Substances—n-Propyl Bromide: 

Proposed Rule Federal Register Vol. 68 

No. 106, June 3, 2003. Enviro Tech 

International, Inc. Comments Regarding 

Proposed Rule & Exhibit A Richard 

Morford, Enviro Tech International. 

August 3, 2003. (EPA–HQ–OAR–2002–

0064–0047) 

Morford, 2003e. Enviro Tech International, 

Inc. Combined Exhibits to Comment 

0047/Morford, 2003e on Proposed Rule 

Richard Morford, Enviro Tech 

International. August 3, 2003. (EPA–HQ–

OAR–2002–0064–0048) 

Morford, 2003f. Initial Comments to 

Protection of Stratospheric Ozone: 

Listing of Substitutes for Ozone 

Depleting Substances—n-Propyl 

bromide: Proposed Rule Federal Register 

Vol. 68 No. 106, June 3, 2003. Richard 

Morford, Enviro Tech International. June 

26, 2003. (EPA–HQ–OAR–2002–0064–

0002) 

Morford, 2003g. Comment regarding 

proposed restriction on isopropyl 

bromide Richard Morford, Enviro Tech 

International. August 3, 2003. (EPA–HQ–

OAR–2002–0064–0042) 

Morford, 2003h. Enviro Tech International 

Inc Comment Regarding iPB Content 

Restriction Exhibit A 04–Aug–2003 

(EPA–HQ–OAR–2002–0064–0046) 

Morford, 2003i. White Paper: ‘‘EPA Is 

Unlawfully Regulating Occupational 

Exposures’’ Attachment to public 

comments. (EPA–HQ–OAR–2003–0064–

0049) 

NTP, 2003. Full citation above in ‘‘Human 

Health’’ section. 

PBT Profiler, 2007. Results from the PBT 

Profiler Tool for 1-bromopropane, CAS 

No. 106–94–5. Downloaded on February 

9, 2007 from http://www.pbtprofiler.net/ 

default.asp. (EPA–HQ–OAR–2002–

0064–0168) 

Risotto, 2003. Full citation above in ‘‘Human 

Health’’ section. 

Rodricks, 2002. Full citation above in 

‘‘Human Health’’ section. 

Rozman and Doull, 2005. Rozman and Doull, 

2005. Presentation by Drs. Rozman and 

Doull at the North American Congress of 

Clinical Toxicologists. September 14, 

2005. (EPA–HQ–OAR–2002–0064–0126) 

RTI, 2005. Full citation above in ‘‘Human 

Health’’ section. 

Ruckriegel, 2003. Comment on n-Propyl 

Bromide Recommended Workplace 

Exposure Level in Proposed Rule 

Published in Federal Register Vol. 68, 

No. 106, June 3, 2003. August 2, 2003 

(EPA–HQ–OAR–2002–0064–0055) 

Rusch and Bernhard, 2003. Comments on 

proposed regulation of n-propyl bromide 

from Steven Bernhardt and George 

Rusch, Honeywell. August 1, 2003. 

(EPA–HQ–OAR–2002–0064–0059) 

Rusch, 2003. Late comments on proposed 

regulation of n-propyl bromide from 

George Rusch, Honeywell. (EPA–HQ–

OAR–2002–0064–0068) 

Sekiguchi, 2002. Full citation above in 

‘‘Human Health’’ section. 

SLR International, 2001. Full citation above 

in ‘‘Human Health’’ section. 

Smith, 2003. Comments on Protection of 

Stratospheric Ozone: Listing of 

Substitutes for Ozone-Depleting 

Substances—n-Propyl Bromide, FR Vol. 

68, No. 106, June 3, 2003. R.L. Smith, 

Albemarle Corporation. July 23, 2003. 

(EPA–HQ–OAR–2002–0064–0067) 

Stelljes, 2003. Comments from Dr. Marc 

Stelljes, SLR International, on proposed 

rule on n-propyl bromide. (HQ–EPA–

OAR–2002–0064–0022) 

Stelljes and Wood, 2004. Full citation above 

in ‘‘Human Health’’ section. 

Stelljes, 2005. Full citation above in ‘‘Human 

Health’’ section. 

TERA, 2004. Full citation above in ‘‘Human 

Health’’ section. 

U.S. EPA, 1994b. Full citation above in 

‘‘Human Health’’ section. 

U.S. EPA, 1996. Full citation above in 

‘‘Human Health’’ section. 

U.S. EPA, 2003. Summary of Data on 

Workplace Exposure to n-Propyl 

Bromide, May 21, 2003. EPA’s summary 

of exposure data from nPB suppliers and 

NIOSH. (EPA–HQ–OAR–2002–0064–

0015 and –0016) 

Weiss Cohen, 2003. Comments from Tammi 

Weiss Cohen, Dead Sea Bromine Group. 

Comments To Federal Register Proposed 

Rules Of June 3, 2003, On Protection Of 

Stratospheric Ozone: Listing Of 

Substitutes For Ozone-Depleting 

Substances—N Propyl Bromide. (EPA–

HQ–OAR–2002–0064–0038) 

Werner, 2003. Full citation above in ‘‘Human 

Health’’ section. 

WIL, 2001. Full citation above in ‘‘Human 

Health’’ section. 

Yamada et al., 2003. Full citation above in 

‘‘Human Health’’ section. 

Executive Orders and Statutes 

Kassem, 2003. Full citation above for 

‘‘Decisions for Each Sector and End Use’’

section. 

Ultronix, 2001. Response to questionnaire 

from EPA by C. Wolf, Ultronix, 2001. 

(A–2001–07, II–D–76) 

Tattersall, 2004. Conversation between M. 

Sheppard, EPA, and Tom Tattersall, 

MicroCare Corporation. (EPA–HQ–OAR–

2002–0064–0171) 


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Federal Register / Vol. 72, No. 103 / Wednesday, May 30, 2007 / Rules and Regulations 30167 

U.S. EPA, 2003. Full citation above for 

‘‘Human Health’’ section. 

U.S. EPA, 2007. Analysis of Economic 

Impacts of Final nPB Rulemaking for 

Cleaning Solvent Sector. 2007. 

List of Subjects in 40 CFR Part 82 

Environmental protection, 

Administrative practice and procedure, 

Air pollution control, Reporting and 

recordkeeping requirements. 

Dated: May 15, 2007. 

Stephen L. Johnson, 

Administrator. 

Appendix A: Summary of Decision 

SOLVENT CLEANING ACCEPTABLE SUBSTITUTE

End uses Substitute Decision Further information 

Metals cleaning, electronics 

cleaning, and precision 

cleaning.

n-propyl bromide (nPB) as 

a substitute for CFC–113 

and methyl chloroform.

Acceptable ......................... EPA recommends the use of personal protective 

equipment, including chemical goggles, flexible laminate protective gloves and chemical-resistant clothing. 

EPA expects that all users of nPB would comply with 

any final Permissible Exposure Limit that the Occupational Safety and Health Administration issues in 

the future under 42 U.S.C. 7610(a). 

nPB, also known as 1-bromopropane, is Number 106–

94–5 in the Chemical Abstracts Service (CAS) Registry. 

[FR Doc. E7–9707 Filed 5–29–07; 8:45 am] 

BILLING CODE 6560–50–P 


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