[Federal Register: May 30, 2007 (Volume 72, Number 103)] [Proposed Rules] [Page 30168-30207] From the Federal Register Online via GPO Access [wais.access.gpo.gov] [DOCID:fr30my07-28] [[Page 30168]] ----------------------------------------------------------------------- ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 82 [EPA-HQ-OAR-2002-0064; FRL-8316-7] RIN 2060-AK26 Protection of Stratospheric Ozone: Listing of Substitutes for Ozone-Depleting Substances--n-Propyl Bromide in Adhesives, Coatings, and Aerosols AGENCY: Environmental Protection Agency. ACTION: Notice of Proposed Rulemaking. ----------------------------------------------------------------------- SUMMARY: Pursuant to the U.S. Environmental Protection Agency's (EPA or ``we'') Significant New Alternatives Policy (SNAP) program, this action proposes to list n-propyl bromide (nPB) as an unacceptable substitute for methyl chloroform, chlorofluorocarbon (CFC)-113, and hydrochlorofluorocarbon (HCFC)-141b when used in adhesives or in aerosol solvents because nPB in these end uses poses unacceptable risks to human health when compared with other substitutes that are available. In addition, EPA takes comment on alternate options that would find nPB acceptable subject to use conditions in adhesives or in aerosol solvents. This action also proposes to list nPB as acceptable, subject to use conditions, as a substitute for methyl chloroform, CFC- 113, and hydrochlorofluorocarbon (HCFC)-141b in the coatings end use. This proposal supersedes EPA's proposal of June 3, 2003 on the acceptability of nPB as a substitute for ozone-depleting substances for aerosols and adhesives. DATES: Comments must be received in writing by July 30, 2007. Under the Paperwork Reduction Act, comments on the information collection provisions must be received by the Office of Management and Budget (OMB) on or before June 29, 2007. Any person interested in requesting a public hearing, must submit such request on or before June 29, 2007. If a public hearing is requested, a separate notice will be published announcing the date and time of the public hearing and the comment period will be extended until 30 days after the public hearing to allow rebuttal and supplementary information regarding any material presented at the public hearing. Inquiries regarding a public hearing should be directed to the contact person listed below. ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ- OAR-2002-0064, by one of the following methods: http://www.regulations.gov. Follow the on-line instructions for submitting comments. E-mail: A-And-R-Docket@epa.gov. Mail: Air and Radiation Docket, Environmental Protection Agency, Mailcode 6102T, 1200 Pennsylvania Ave., NW., Washington DC 20460, Attention Docket ID No. EPA-HQ-OAR-2002-0064. In addition, please mail a copy of your comments on the information collection provisions to the Office of Information and Regulatory Affairs, Office of Management and Budget (OMB), Attn: Desk Officer for EPA, 725 17th St., NW., Washington, DC 20503. Hand Delivery: EPA Docket Center, (EPA/DC) EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC, Attention Docket ID No. EPA-HQ-OAR-2002-0064. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information. Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR- 2002-0064. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at http://www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site is an ``anonymous access'' system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through http://www.regulations.gov , your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional instructions on submitting comments, go to Section I.B. of the SUPPLEMENTARY INFORMATION section of this document. Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some information is not publicly available, i.e., 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. The Public Reading Room 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 I. General Information A. Does this action apply to me? B. What should I consider as I prepare my comments for EPA? 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. Where can I get additional information about the SNAP program? III. What is EPA proposing today? A. What is n-propyl bromide? B. What industrial end uses are included in our proposed decision? C. What is the proposed text for EPA's listing decisions? D. What does an unacceptability determination on adhesives and aerosols mean? E. What is the scope of the proposed determination for coatings? [[Page 30169]] IV. What criteria did EPA consider in preparing this proposal? A. Availability of Alternatives to Ozone-Depleting Substances B. Impacts on the Atmosphere and Local Air Quality C. Ecosystem and Other Environmental Impacts D. Flammability and Fire Safety E. Health impacts and exposure V. How did EPA assess impacts on human health? A. Newly Available Exposure Data B. Newly Available Data on Health Effects C. Evaluation of Acceptable Exposure Levels for the Workplace D. Other Analyses of nPB Toxicity E. Community Exposure Guideline VI. What listing is EPA proposing for each end use, and why? A. Aerosol Solvents B. Adhesives C. Coatings VII. What other regulatory options did EPA consider? A. Alternative Option for Comment: Acceptable With Use Conditions Requiring Exposure Limit and Monitoring B. Regulatory Options Where nPB Would Be Acceptable With Use Conditions Requiring Specific Equipment VIII. What are the anticipated costs of this regulation to the regulated community? IX. How do the decisions for EPA's June 2003 proposal compare to those for this proposal? X. How can I use nPB as safely as possible? XI. 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 XII. References I. General Information A. Does this action apply to me? This proposed rule would regulate the use of n-propyl bromide as an aerosol solvent and as a carrier solvent in adhesives and coatings. Businesses in these end uses that currently might be using nPB, or might want to use it in the future, include: 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. Foam fabricators that glue pieces of polyurethane foam together or foam cushion manufacturers that glue fabric around a cushion. Furniture manufacturers that use adhesive to attach wood parts to floors, tables and counter tops. A company that manufactures ammunition for the U.S. Department of Defense. Regulated entities may include: Table 1.--Potentially Regulated Entities, by North American Industrial Classification System (NAICS) Code or Subsector ---------------------------------------------------------------------------------------------------------------- NAICS code or Category subsector Description of regulated entities ---------------------------------------------------------------------------------------------------------------- Industry...................................... 331 Primary Metal Manufacturing. Industry...................................... 332 Fabricated Metal Product Manufacturing. Industry/Military............................. 332992 Small Arms Ammunition 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. Industry...................................... 326150 Urethane and Other Foam Product (except Polystyrene) 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 should I consider as I prepare my comments for EPA? 1. Submitting Confidential Business Information (CBI). Do not submit this information to EPA through http://www.regulations.gov or e-mail. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD ROM that you mail to EPA, mark the outside of the disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2. 2. Tips for Preparing Your Comments. When submitting comments, remember to: Identify the rulemaking by docket number and other identifying information (subject heading, Federal Register (FR) date and page number). Follow directions--The agency may ask you to respond to specific questions or organize comments by referencing a Code of Federal Regulations (CFR) part or section number. Explain why you agree or disagree; suggest alternatives and substitute language for your requested changes. Describe any assumptions and provide any technical information and/or data that you used. If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced. Provide specific examples to illustrate your concerns, and suggest alternatives. Explain your views as clearly as possible, avoiding the use of profanity or personal threats. Make sure to submit your comments by the comment period deadline identified. 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 [[Page 30170]] 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-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 NIOSH--National Institute for Occupational Safety and Health NOAEL--No Observed Adverse Effect Level NOEL--No Observed Effect Level nPB--ln-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 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 Value(tm) 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 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 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 ozone- depleting substance (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 [[Page 30171]] 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. 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 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. C. 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 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 proposing today? In this action, EPA proposes to list n-propyl bromide (nPB) as (1) unacceptable for use as a substitute for CFC-113,\1\ methyl chloroform \2\ and HCFC-141b \3\ in the adhesive and aerosol solvent end uses; and (2) acceptable subject to use conditions (limited to coatings at facilities that, as of May 30, 2007, have provided EPA with information demonstrating their ability to maintain acceptable workplace exposures) as a substitute for methyl chloroform, CFC-113, and HCFC-141b in the coatings end use. This Notice of Proposed Rulemaking (NPRM) supersedes the NPRM published on June 3, 2003 (68 FR 33284) for aerosol solvents and adhesives. --------------------------------------------------------------------------- \1\ CFC-113 is also referred to as Freon-113, or 1,1,2- trifluoro-1,2,2-trichloroethane. Its CAS Reg. No. is 76-13-1. \2\ Methyl chloroform is also referred to as 1,1,1- trichloroethane, TCA, MCF, or 1,1,1. Its CAS Reg. No. is 71-55-6. \3\ HCFC-141b is also referred to as 1,1-dichloro-1- fluoroethane. Its CAS Reg. No. is 1717-00-6. --------------------------------------------------------------------------- A. 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[supreg], EnSolv[supreg], and Solvon[supreg] cleaners; Pow-R-Wash[supreg] 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. B. What industrial end uses are included in our proposed decision? This proposal addresses the use of n-propyl bromide in the aerosol solvent end use of the aerosol sector and the adhesives and coatings end uses in the adhesives, coatings, and inks sector as discussed below. EPA is issuing a decision on the use of nPB in metals, electronics, and precision cleaning in a separate final rule. EPA has insufficient information for ruling on other end uses or sectors where nPB might be used (e.g., inks, foam blowing, fire suppression). 1. Aerosol Solvents We understand that nPB is being used as an aerosol solvent in: Lubricants, coatings, or cleaning fluids for electrical or electronic equipment; Lubricants, coatings, or cleaning fluids for aircraft maintenance; or [[Page 30172]] Spinnerrette lubricants and cleaning sprays used in the production of synthetic fibers. 2. Adhesives Types of adhesives covered under the SNAP program are those that formerly used methyl chloroform, specifically, adhesives for laminates, flexible foam, hardwood floors, tire patches, and metal to rubber adhesives. Of these applications, nPB-based adhesives have been used most widely in spray adhesives used in manufacture of foam cushions, and to a lesser degree in laminate adhesives. 3. Coatings The SNAP program regulates the use of carrier solvents in durable coatings, including paints, varnishes, and aerospace coatings (59 FR 13118). The SNAP program currently does not regulate carrier solvents in lubricant coatings, such as silicone coatings used on medical equipment (59 FR 13119). Methyl chloroform has been used as a carrier solvent in coatings, and to a much lesser degree, HCFC-141b also has been a carrier solvent. This rule responds to a submission from a facility that is substituting methyl chloroform with nPB as an ammunition coating (sealant). C. What is the proposed text for EPA's listing decisions? In the proposed regulatory text at the end of this document, you will find our proposed decisions for those end uses for which we have proposed nPB as unacceptable or acceptable subject to use conditions. The proposed conditions listed in the ``Use Conditions'' column would be enforceable while information contained in the ``Further Information'' column of those tables provides additional recommendations on the safe use of nPB. Our proposed decisions for each end use are summarized below in tables 2 through 4. Proposed Listings Table 2.--Aerosols Proposed Unacceptable Substitutes ---------------------------------------------------------------------------------------------------------------- End Use Substitute Decision Further information ---------------------------------------------------------------------------------------------------------------- Aerosol solvents.................. n-propyl bromide (nPB) as Unacceptable......... EPA finds unacceptable a substitute for CFC-113, risks to human health in HCFC-141b, and methyl this end use compared to chloroform. other available alternatives. nPB, also known as 1-bromopropane, is Number 106-94-5 in the CAS Registry. ---------------------------------------------------------------------------------------------------------------- Table 3.--Adhesives, Coatings, and Inks Proposed Unacceptable Substitutes ---------------------------------------------------------------------------------------------------------------- Enduse Substitute Decision Further information ---------------------------------------------------------------------------------------------------------------- Adhesives......................... n-propyl bromide (nPB) as Unacceptable......... EPA finds unacceptable a substitute for CFC-113, risks to human health in HCFC-141b, and methyl this end use compared to chloroform. other available alternatives. nPB, also known as 1-bromopropane, is Number 106-94-5 in the CAS Registry. ---------------------------------------------------------------------------------------------------------------- Table 4.--Adhesives, Coatings, and Inks Substitutes That Are Proposed Acceptable Subject to Use Conditions ---------------------------------------------------------------------------------------------------------------- End Use Substitute Decision Use conditions Further information ---------------------------------------------------------------------------------------------------------------- Coatings............ n-propyl bromide Acceptable subject Use is limited to EPA recommends the use (nPB) as a to use conditions. coatings facilities of personal protective substitute for that, as of May 30, equipment, including methyl chloroform, 2007, have provided chemical goggles, CFC-113, and HCFC- EPA information flexible laminate 141b. demonstrating their protective gloves and ability to maintain chemical-resistant acceptable workplace clothing. exposures. 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 CAS Registry. ---------------------------------------------------------------------------------------------------------------- Note: As of May 30, 2007, the Lake City Army Ammunition Plant is the only facility using nPB in coatings that has provided information to EPA that meets this condition. D. What does an unacceptability determination on adhesives and aerosols mean? In this action, EPA is proposing to find nPB unacceptable as a substitute for methyl chloroform, CFC-113, and HCFC-141b for use as a carrier solvent in adhesives and as an aerosol solvent. If this proposal were to become final, it would be illegal to use nPB or blends of nPB and other solvents in adhesives or in aerosol solvent formulations as a substitute for ozone-depleting substances. E. What is the scope of the proposed determination for coatings? We propose to list nPB as an acceptable substitute, subject to use conditions, for methyl chloroform, CFC-113, and HCFC-141b in coatings for facilities that, as of May 30, 2007, have [[Page 30173]] provided EPA information demonstrating their ability to maintain acceptable workplace exposures. EPA has received a petition to allow use of nPB for the ammunition coating application at Lake City Army Ammunition Plant. This is the only coatings application or facility for which EPA has exposure and usage data demonstrating an ability to maintain workplace exposure levels below even the minimum level of the range of exposures that EPA is considering to be potentially acceptable (i.e., 17 to 30 ppm) (see section IV.E for an evaluation of the health risks associated with nPB). If other facilities are interested in using nPB as a substitute for methyl chloroform, CFC-113, or HCFC-141b in their coatings application, or if a person wishes to market nPB for such use, then the interested party would need to make a submission under the SNAP program. IV. What criteria did EPA consider in preparing this proposal? 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 ground-level 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 or spray adhesives used in foam fabrication. In those consumer products made using nPB, such as a piece of furniture or a computer, the nPB would have evaporated long before a consumer would purchase the item. Therefore, we believe there is no consumer exposure risk to evaluate 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 carrier solvent in adhesives to other available or potentially available adhesive 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 aerosol solvents, but not all may be appropriate for a specific application because of differences in materials compatibility, flammability, degree of cleanliness required, local environmental requirements, and other factors. 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, environmental risks were not sufficient to find nPB unacceptable in any of the evaluated end uses. However, the overall risks to human health, and particularly the risks to worker health, are sufficiently high in the adhesive and aerosol solvent end uses to warrant our proposal to find nPB unacceptable. A. Availability of Alternatives to Ozone-Depleting Substances Other alternatives are available in each end use considered in this proposal. Examples of other available alternatives for aerosol solvents that have already been found acceptable or acceptable subject to use conditions under the SNAP program include water-based formulations, alcohols, ketones, esters, ethers, terpenes, HCFC-141b, HCFC-225ca/cb, hydrofluoroethers (HFEs), hydrofluorocarbon (HFC)-4310mee, HFC-365mfc, HFC-245fa, hydrocarbons, trans-1,2-dichloroethylene, methylene chloride, trichloroethylene \4\ (TCE), perchloroethylene \5\, and parachlorobenzotrifluoride (PCBTF). Of these, hydrocarbons, alcohols, blends of trans-1,2-dichloroethylene and HFEs or HFCs, and HCFC-225ca/ cb are most likely to be used in the same applications as nPB. nPB is already commercially available in aerosols. Its use is primarily for electrical contact cleaning, with some use for benchtop cleaning applications (Williams, 2005). --------------------------------------------------------------------------- \4\ Also called trichlorethene or TCE, C2Cl3H, CAS Reg. No. 79-01-6. \5\ Also called PERC, tetrachloroethylene, or tetrachloroethene, C2Cl4, CAS Reg. No. 127-18-4. --------------------------------------------------------------------------- Many alternatives are also available for use in adhesives, coatings, and inks: Water-based formulations, high solid formulations, alcohols, ketones, esters, ethers, terpenes, HFEs, hydrocarbons, trans- 1,2-dichloroethylene, chlorinated solvents, PCBTF, and a number of alternative technologies (e.g., powder, hot melt, thermoplastic plasma spray, radiation-cured, moisture-cured, chemical-cured, and reactive liquid). Of these, the alternative adhesives most likely to be used in the same applications as nPB are water-based formulations, adhesives with methylene chloride, and flammable adhesives with acetone (IRTA, 2000). nPB is already used in adhesives, and particularly in foam fabrication and in constructing seating for aircraft (IRTA, 2000; Seilheimer, 2001). To our knowledge, nPB is potentially available as a carrier solvent in coatings, but has not yet been commercialized, except for use by one facility, the Lake City Army Ammunition Plant. The Lake City Army Ammunition Plant evaluated twenty-nine carrier solvent alternatives to methyl chloroform and determined that nPB is the only satisfactory alternative for their application given the current process at that facility (Harper, 2005). 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), 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 as an aerosol solvent. There are other acceptable solvents for aerosols, adhesives, and coatings that essentially have no ODP--aqueous cleaners, HFEs, HFC-4310mee, HFC- 365mfc, HFC-245fa, hydrocarbons, volatile methyl siloxanes (VMSs), methylene chloride, TCE, perchloroethylene, and PCBTF. [[Page 30174]] Based on this information, we do not believe the use of nPB within the U.S., and within the end-uses reviewed in this rulemaking, poses a significantly greater risk to the ozone layer than other available substitutes. 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). Because the ODP for nPB is higher when used in the tropics,\6\ 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. 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, 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): --------------------------------------------------------------------------- \6\ nPB 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). --------------------------------------------------------------------------- 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 n-propyl bromide, * * * paying particular attention to: (a) Obtaining more complete data on production and uses of n-propyl bromide as well as emissions of n-propyl 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 twenty-seventh meeting of the Open-ended Working Group for the consideration of the Nineteenth Meeting of the Parties. (MOP 18, 2006) 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 nonattainment 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 VOC-exempt solvents that are acceptable ODS substitutes include HFC-245fa, HCFC-225ca/cb, HFC-365mfc and HFC- 4310mee for aerosol solvents, and methylene chloride, perchloroethylene, HFE-7100, HFE-7200, PCBTF, acetone, and methyl acetate for 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 5). 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 milligrams per liter (mg/l), which is greater and thus less toxic than an LC50 of 10 mg/l, one of EPA's criteria for listing under the Toxics Release Inventory (US EPA, 1992; ICF, 2004a). Based on its relatively low bioconcentration factor and log Kow value (logarithm of the octanol-water partition coefficient), nPB is not prone to bioaccumulation. Table 5 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; acetone, a commonly-used carrier solvent in adhesives; trichloroethylene, a solvent used for metals, electronics, and precision cleaning that could potentially be used in aerosol or adhesive end-uses; and methyl chloroform, an ODS that nPB would replace. [[Page 30175]] Table 5.--Ecosystem and Other Environmental Properties of nPB and Other Solvents -------------------------------------------------------------------------------------------------------------------------------------------------------- Description of Value for trans- Property environmental Value for nPB 1,2-dichloro- Value for acetone Value for Value for methyl property ethylene trichloroethylene chloroform -------------------------------------------------------------------------------------------------------------------------------------------------------- Koc, organic-carbon partition Degree to which a 330 (Source: ICF, 32 to 49 (Source: 5.4 (Source: 106 to 460 (Source: 152 (Source: U.S. coefficient. substance tends 2004a). ATSDR, 1996). ATSDR, 1994). ATSDR, 1997). EPA, 1994a). 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. Break down in water............ Mechanism and Hydrolysis is Photolytic Biodegradation is Volatilization and Volatilization speed with which significant. decomposition, most significant biodegradation most most a compound breaks Hydrolysis half- dechlorination form of breakdown significant, with significant; down in the life of 26 days and (Source: ATSDR, hydrolysis biodegradation environment. (Source: ICF, biodegradation 1994). relatively and hydrolysis (Hydrolysis half- 2004a). are significant; insignificant. also occur life values > 25 hydrolysis not Hydrolysis half- (Source: ATSDR, weeks\*\ are of significant life of 10.7 to 30 2004). concern.). (Source: ATSDR, months (Source: 1996). ATSDR, 1997). Volatilization half-life from Tendency to 3.4 hours-4.4 days 3 to 6.2 hours 7.8 to 18 hours 3.4 hours to 18 days Hours to weeks surface waters. volatilize and (Source: ICF, (Source: ATSDR, (Source: ATSDR, (Source: ATSDR, (Source: U.S. pass from water 2004a). 1996). 1994). 1997). EPA, 1994a). into the air. LC50 (96 hours) for fathead Concentration at 67 mg/L (Source: 108 mg/L (Source: 7280 to 8120 mg/L 40.7 to 66.8 mg/L 52.8 to 105 mg/L minnows. which 50% of Geiger, 1988). U.S. EPA, 1980). (Source: Fisher (Source: NPS, 1997). (Source: U.S. animals die from Scientific, 2001). EPA, 1994a). toxicity after exposure for 4 days. log Kow........................ Logarithm of the 2.10 (Source: ICF, -0.48 (Source: -0.24 (Source: 2.38 (Source: 2.50 (Source: octanol/water 2004a). LaGrega et al., LaGrega et al., LaGrega et al., LaGrega et al., partition 2001, p. 1119). 2001, p. 1117). 2001, p. 1127). 2001, p. 1127). coefficient, a measure of tendency to accumulate in fat. Log Kow values >3 \;*\ indicate high tendency to accumulate. Bioconcentration factor........ High factors 23 (Source: HSDB, 5 to 23 (Source: < 1 (Source: ATSDR, 10 to 100 (Source: < 9 (Source: U.S. (>1000)\*\ 2004). ATSDR, 1996). 1994). ATSDR, 1997). EPA, 1994a). indicate strong tendency for fish to absorb the chemical from water into body tissues. -------------------------------------------------------------------------------------------------------------------------------------------------------- \*\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. We conclude that nPB does not pose a significantly greater risk to the environment than other available alternatives, and that the use of nPB within the U.S. should not be prohibited under the SNAP program on the basis of its environmental impacts. 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, 2003b, and 2003c; [[Page 30176]] 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 non-flammable 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. Health Impacts and Exposure In evaluating potential human health impacts of nPB used as a substitute for ozone-depleting substances, EPA considered impacts on both exposed workers and on the general population. Using the same approach finalized in the original SNAP rulemaking, EPA evaluated the available toxicity data using EPA guidelines to develop health-based criteria to characterize human health risks (US EPA, 1994b. Inhalation Reference Concentration Guidelines; U.S. EPA, 1991. Guidelines for Developmental Toxicity Risk Assessment; U.S. EPA, 1995a. Benchmark Dose guidelines; U.S. EPA, 1996. Guidelines for Reproductive Toxicity Risk Assessment). To assess human health risks, EPA followed the four basic steps of risk assessment outlined by the National Academy of Sciences: hazard identification, dose-response relationship, exposure assessment, and risk characterization (NAS, 1983). First, EPA examined available studies on nPB's effects. Second, EPA considered the acceptable exposure levels for evaluating worker exposure and a community exposure guideline (CEG) for evaluating exposure to the general population based upon inhalation exposure. Third, EPA compared the acceptable exposure levels and CEG to available exposure data and projections of exposure levels to assess exposure, including new exposure data available since publication of the June 2003 NPRM. Finally, EPA decided whether there was sufficient evidence indicating that nPB could be used as safely as other alternatives available in a particular end use. Authority To Set an Acceptable Exposure Limit Two commenters on the June 2003 NPRM said that EPA has no jurisdiction to develop any acceptable exposure limit (AEL) designed to be applicable to a workplace environment and that only the Occupational Safety and Health Administration (OSHA) has that authority (Stelljes, 2003; Morford, 2003d). In contrast, another commenter said that EPA has the authority to set an AEL for nPB under section 612 of the Clean Air Act, has done so in the past for other chemicals (e.g., HFC-4310mee, HCFC-225ca/cb), and should require the AEL as a use condition (Risotto, 2003). EPA believes it has the authority to calculate exposure limits for the workplace under section 612. Section 612(c) specifically states that The Administrator shall issue regulations: providing that it shall be unlawful to replace any class I or class II substance with any substitute substance which the Administrator determines may present adverse effects to human health or the environment, where the Administrator has identified an alternative to such replacement that-- (1) reduces the overall risk to human health and the environment; and (2) is currently or potentially available. Thus, we 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, as required by the Clean Air Act. In order to compare risks to human health, EPA performs quantitative risk assessments on different chemicals comparing exposure data and exposure limits, following the process described above by the National Academies of Science (NAS, 1983) and as described in the preamble to the original final SNAP rule (March 18, 1994; 59 FR 13066). Because most humans who are exposed to nPB are exposed in the workplace, the appropriate exposure data and exposure limits to protect human health must include workplace exposure data and acceptable exposure limits for the workplace. Because there is wide disparity in acceptable exposure limits for nPB developed by industry, ranging 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), and because there is not a Permissible Exposure Limit for nPB set by the Occupational Safety and Health Administration, EPA believes it is appropriate to independently evaluate the human health risks associated with use of nPB in the workplace. Similarly, EPA has developed a community exposure guideline to assess the human health effects of nPB exposure to the general public. Skin Notation 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). 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 proposing to include a skin notation for nPB in the information provided to users associated with this rulemaking because of the relatively low level of absorption. The American Conference of Governmental Industrial Hygienists (ACGIH) provides no skin notation in its documentation for threshold limit values (TLVs) 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. 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 vendors to include such precautions in their Material Safety Data Sheets (MSDSs). EPA requests comment on whether it would be useful, in lieu of a skin notation to add the following statement in the ``further information'' column of each end use where we find nPB acceptable with restrictions: ``EPA recommends the use of personal protective equipment, including chemical goggles, flexible laminate protective gloves and chemical-resistant clothing, when using nPB.'' EPA also considered the potential health effects of contamination of nPB formulations with isopropyl bromide [[Page 30177]] (iPB).\7\ In the June 2003 proposed rule, we proposed as a use condition that nPB formulations contain no more than 0.05% iPB by weight. One commenter opposed the proposed use condition, stating that it places an undue legal burden on end users, rather than the manufacturers of raw materials, that it would not benefit worker safety, and that the nPB industry has worked to reduce iPB content below 0.05% (Morford, 2003e). We agree that industry has met this contamination limit for several years without regulation. Furthermore, EPA agrees that if users are exposed to nPB concentrations no higher than the highest potentially acceptable concentration (30 ppm), a worker's exposure to iPB will be sufficiently low to avoid adverse effects. Therefore, this proposed rule does not include a use condition limiting iPB content in nPB formulations. --------------------------------------------------------------------------- \7\ iPB is also referred to as 2-bromopropane, 2-propyl bromide, or 2-BP. Its CAS registry number is 75-26-3. --------------------------------------------------------------------------- 1. Workplace Risks 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 exposu