Protection of Stratospheric Ozone; Listing of Substitutes for Ozone-Depleting Substances

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 82

[FRL-6301-8]

RIN 2060-AG12

Protection of Stratospheric Ozone; Listing of Substitutes for

Ozone-Depleting Substances

AGENCY: Environmental Protection Agency.

ACTION: Request for data and advance notice of proposed rulemaking.

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SUMMARY: This action requests comments and information on n-propyl

bromide (nPB) under the U.S. Environmental Protection Agency's (EPA)

Significant New Alternatives Policy (SNAP) program. SNAP implements

section 612 of the amended Clean Air Act of 1990 (CAAA), which requires

EPA to evaluate substitutes for ozone depleting substances (ODSs) to

reduce overall risk to human health and the environment. Through these

evaluations, SNAP generates lists of acceptable and unacceptable

substitutes for each of the major industrial use sectors. The intended

effect of the SNAP program is to expedite movement away from ozone

depleting compounds while avoiding a shift into substitutes posing

other environmental or health problems.

Through this Advance Notice of Proposed Rulemaking (ANPR), the

Agency hopes to receive information as part of the development of

effective regulatory options on the listing of nPB as acceptable or

unacceptable for the various submitted end-uses under SNAP. This action

notifies the public of the availability of information regarding nPB

and the Agency hopes that this action will provide the public an

opportunity to provide input at an early stage in the decision-making

process.

This notice does not constitute a final, or even preliminary,

decision by the Agency. Based on information collected as part of this

ANPR, EPA intends to propose a future determination regarding the

acceptability or unacceptability of nPB as a substitute for class I and

class II ozone depleting substances and, if acceptable, an occupational

exposure limit (OEL) for nPB. This limit would be designed to protect

worker safety until the Occupational Safety and Health Administration

(OSHA) sets its own standards under Public Law 91-596. However, until a

final determination is made, users of nPB should exercise caution in

the manufacture, handling, and disposal of this chemical.

EPA has received petitions under CAAA Section 612(d) to add nPB to

the list of acceptable alternatives for class I and class II ozone

depleting substances in the solvent sector for general metals,

precision, and electronics cleaning, as well as in aerosol and adhesive

applications.

DATES: Written comments on data provided in response to this notice

must be submitted by April 19, 1999.

ADDRESSES: Comments on and materials supporting this advanced notice

are collected in Air Docket # A-92-13, U.S. Environmental Protection

Agency, 401

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M Street, S.W., Room M-1500, Washington, D.C., 20460. The docket is

located at the address above in room M-1500, First Floor, Waterside

Mall. The materials may be inspected from 8 am until 4 pm Monday

through Friday. A reasonable fee may be charged by EPA for copying

docket materials.

FOR FURTHER INFORMATION CONTACT: The Stratospheric Ozone Hotline at

(800)-296-1996 or Melissa Payne at (202) 564-9738 or fax (202) 565-

2096, Analysis and Review Branch, Stratospheric Protection Division,

Mail Code 6205J, Washington, D.C. 20460. Overnight or courier

deliveries should be sent to our 501 3rd Street, N.W., Washington, DC,

20001 location.

SUPPLEMENTARY INFORMATION:

This action is divided into four sections:

I. Section 612 Program

A. Statutory Requirements

B. Regulatory History

II. Listing of Substitutes

III. Information Needs

A. Objective

B. Ozone Depletion Potential

C. Toxicity

D. Potential Use

IV. Regulatory Options

V. References

I. Section 612 Program

A. Statutory Requirements

Section 612 of the Clean Air Act authorizes EPA to develop a

program for evaluating alternatives to ozone-depleting substances. This

program is referred to as the Significant New Alternatives Policy

(SNAP) program. Section 612(c) requires EPA to publish a list of the

substitutes unacceptable for specific uses and a corresponding list of

acceptable alternatives for specific uses. 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).

B. Regulatory History

On March 18, 1994, EPA published the Final Rulemaking (59 FR 13044)

which described the process for administering the SNAP program and

issued EPA's first acceptability and unacceptability lists for

substitutes in the major industrial use sectors. These sectors include:

refrigeration and air conditioning; foam blowing; solvent cleaning;

fire suppression and explosion protection; sterilants; aerosols;

adhesives, coatings and inks; and tobacco expansion. These sectors

comprise the principal industrial sectors that historically consume

large volumes of ozone-depleting compounds.

The Agency defines a ``substitute'' as any chemical, product

substitute, or alternative manufacturing process, whether existing or

new, that could replace a class I or class II substance. Anyone who

produces a substitute 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 chemical manufacturers, but may include

importers, formulators or end-users when they are responsible for

introducing a substitute into commerce.

II. Listing of Substitutes

To develop the lists of unacceptable and acceptable substitutes,

EPA conducts screens of health and environmental risks posed by various

substitutes for ozone-depleting compounds in each use sector. The

outcome of these risk screens can be found in the public docket, as

described above in the Addresses portion of this document.

Under section 612, the Agency has considerable discretion in the

risk management decisions it can make in SNAP. The Agency has

identified five possible decision categories: acceptable; acceptable

subject to use conditions; acceptable subject to narrowed use limits;

unacceptable; and pending. Fully acceptable substitutes, i.e., those

with no restrictions, can be used for all applications within the

relevant sector end-use. Conversely, it is illegal to replace an ODS

with a substitute listed by SNAP as unacceptable. A pending listing

represents substitutes for which the Agency has not received complete

data or has not completed its review of the data.

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. Such

substitutes are placed on the ``acceptable, subject to use,

conditions'' lists. Use of such substitutes in ways that are

inconsistent with such use conditions renders these substitutes

unacceptable and subjects the user to enforcement for violation of

section 612 of the Clean Air Act.

Even though the Agency can restrict the use of a substitute based

on the potential for adverse effects, it may be necessary to permit a

narrowed range of use within a sector end-use because of the lack of

alternatives for specialized applications. Users intending to adopt a

substitute acceptable with narrowed use limits must ascertain that

other acceptable alternatives are not technically feasible. Companies

must document the results of their evaluation, and retain the results

on file for the purpose of demonstrating compliance. This documentation

shall include descriptions of substitutes examined and rejected,

processes or products in which the substitute is needed, reason for

rejection of other alternatives, e.g., performance, technical or safety

standards, and the anticipated date other substitutes will be available

and projected time for switching to other available substitutes. Use of

such substitutes in applications and end-uses which are not specified

as acceptable in the narrowed use limit renders these substitutes

unacceptable.

III. Information Needs

A. Objective

As noted above, the purpose of today's notice is to elicit the

voluntary submission of information on nPB as a substitute for class I

and class II substances. Listed below are the specific areas of

information that will be most useful to the Agency in completing the

risk characterizations needed to make regulatory decisions. However,

any available data pertaining to nPB will be considered by the Agency.

Data submitted in response to this request can be designated as

confidential business information (CBI) under 40 CFR, part 2, subpart

B.

EPA has been reviewing the data available on nPB with regard to its

toxicity and its ozone depletion potential. In order to ascertain the

extent of potential environmental implications associated with the use

of this chemical, the Agency is also interested in estimates of nPB

production and ultimate use in various applications. Based on the

assessment to date, the Agency believes that additional information in

all of these areas is needed before regulatory decisions can be

formulated. This notice is to inform the public of the information gaps

and to make publicly available the data to which the Agency already has

access. In this light, EPA is establishing a docket with all available

information on the environmental and health risks associated with nPB,

and is asking for comments and data that can supplement this

information. EPA is seeking public comment regarding nPB in the

following areas where EPA believes that either significant

uncertainties exist in the available data or the data are incomplete.

These areas are critical to EPA's decision-making on the acceptability

or unacceptability of nPB.

[[Page 8045]]

B. Ozone Depletion Potential

The ozone depletion potential (ODP) of a chemical compound provides

a relative measure of the expected impact on stratospheric ozone per

unit mass of the emission of the compound, as compared to that expected

from the same mass emission of CFC-11 integrated over time. ODP is a

benchmark that has been used by the Parties to the Montreal Protocol to

characterize the relative risks associated with the various ozone-

depleting compounds subject to the Protocol's requirements. Under the

auspices of the United Nations Environment Programme, every four years

the world's leading experts in the atmospheric sciences publish a

scientific assessment, relied upon by the Parties to the Montreal

Protocol for future decisions regarding protection of the stratospheric

ozone layer. These assessments evaluate the impacts of ozone depleting

substances on stratospheric ozone concentrations using ODP. Prior

analyses of ODP conducted by these experts, as well as by others in the

field of atmospheric chemistry, have traditionally focused on compounds

with relatively long atmospheric lifetimes (e.g., three months or

longer) (WMO, 1994).

Recently, EPA has been called upon to review compounds of much

shorter lifetimes, such as nPB, which has an estimated atmospheric

lifetime of only 11 days. Estimates of ODP for nPB based on the current

models lie within the range of 0.006-0.027 (Wuebbles et al., 1997 and

1998). The two-dimensional (2-D) and other models currently used to

estimate the relative effects of long-lived compounds on stratospheric

ozone, however, may not be as useful in measuring effects associated

with compounds with very short atmospheric lifetimes.

Chemicals previously evaluated for ODP have atmospheric lifetimes

sufficiently long to be well-mixed in the troposphere, and 2-D models

have been adequate tools for ODP estimation. Short-lived substances

(i.e., compounds with atmospheric lifetimes shorter than three months)

such as nPB can either reach the stratosphere or, unlike long-lived

compounds, break down in the troposphere. Thus, the amount of bromine

that would be available to affect stratospheric ozone greatly depends

on the complex effects of transport and chemical processes in the

troposphere. Two-dimensional modeling is not designed to accurately

account for variations in chemical concentration at different latitudes

or for atmospheric transport of short-lived compounds. As a result,

there are questions about the adequacy of the ODPs determined with

these models for short-lived chemicals like nPB. Since current models

may not accurately evaluate impacts of these short-lived compounds, EPA

is concerned that it may be difficult to meaningfully compare them to

the longer-lived compounds already controlled.

EPA is presently developing a process to more accurately determine

ODPs for short-lived compounds. Independent atmospheric scientists are

also in the process of refining current atmospheric models for this

same purpose. The models are expected to examine a variety of questions

related to convective transport rates at different latitudes, and the

relative importance of transient versus steady-state effects. EPA

expects this work to increase the accuracy of the ODP estimate for nPB,

as well as for other short-lived compounds, and the Agency anticipates

that these models will produce preliminary results within the next

year. In addition, the Agency is interested in receiving from the

public any other information pertaining to the atmospheric effects and

ozone depletion potential of short-lived atmospheric chemicals (shorter

than three months), and any additional information on the ozone

depletion potential of nPB, specifically. EPA will make any new

information accessible to the public as it becomes available by placing

it in the docket identified in the Addresses section of this document,

and if appropriate, issue a notice of data availability in the Federal

Register to insure that the public is aware of any new information.

C. Toxicity

Information on the toxicity of nPB was submitted to the Agency as

part of the requirements of the SNAP program. Data from the submitters

included the results of newly performed 28-day and 90-day repeated dose

studies, both of which included a functional observation battery. A

consortium of companies interested in nPB was formed after the initial

data were submitted under the SNAP program. Other studies, not

previously available to the public, were also submitted by a company

that is not part of the consortium. Additional studies were available

from the published scientific journals. A list of the studies received,

evaluated, and placed in the docket is appended in Section VI.

EPA reviewed the literature to evaluate the potential metabolites

of nPB and their expected toxicity following inhalation exposure. A

structure-activity relationship analysis for potential carcinogenicity

was part of this evaluation. The pharmacokinetics of nPB and its

metabolites were also examined, as well as reports of other studies

performed under non-guideline protocols. Data on structural analogues

of nPB, such as 2-propyl bromide, were also reviewed. This information,

and the reports of the acute (less than 14-day) studies, 28-day and 90-

day inhalation studies can be used to estimate a tentative exposure

limit for the use of nPB in industrial settings. The ``no observed

adverse effect level'' (NOAEL) for liver effects in the 90-day study of

2000 milligrams per cubic meter (mg/m\3\), or 400 parts per million

(ppm), is a possible basis for setting an industrial exposure guideline

(ICF 1998k). Based on this NOAEL, EPA's preliminary estimate of an

exposure guideline is in the range of 50-100 ppm as an 8-hour time

weighted average. Using the NOAEL for effects on sperm counts and

motility from the Ichihara et al. (1998) study would result in a

preliminary, estimated guideline of 93 ppm, suggesting that a range

from 50-100 ppm would be protective of both liver and testicular

effects. (This limit would be designed to protect worker safety until

the Occupational Safety and Health Administration (OSHA) sets its own

standards under P.L. 91-596. The existence of an EPA standard in no way

bars OSHA from standard-setting under OSHA authorities as defined in

P.L. 91-596.)

EPA also examined the potential uses of nPB in the solvent,

aerosol, and adhesives, coatings and inks sectors and received

additional personal monitoring data for these sectors. Preliminary

consideration of the available personal monitoring data (Smith, 1998)

during solvent, adhesive and aerosol usage indicates that nPB exposures

can generally be kept within the range of 50-100 ppm, although some of

the exposure measurements exceeded this range.

At this time, EPA cannot recommend a firm exposure limit because of

identified areas of uncertainty. The fact that reproductive system

effects have been observed in both rats and humans for the similar

compound, 2-propyl bromide, as well as the report of oligospermia in

rats exposed to nPB, raises concern that insufficient testing has been

completed to fully evaluate these significant endpoints. The industry

consortium has responded to these concerns by initiating studies to

test the developmental and reproductive system effects of nPB. Results

from these studies will not be available for another year.

[[Page 8046]]

Finally, EPA is aware that an isomer of nPB, 2-bromo-propane (2BP;

also known as iso-propyl bromide), can be present as a contaminant in

nPB formulations. Occupational exposure to 2BP has been associated with

anemia and reproductive toxicity (Kim et al., 1996). Reproductive and

hematopoietic effects of 2BP have also been demonstrated in animal

studies (Takeuchi et al., 1997; Ichihara et al., 1996, 1997; Kamijima

et al., 1997a,b). Should nPB be listed as acceptable under SNAP, the

Agency would consider establishing maximum concentration limits for 2BP

in applications involving nPB.

EPA is presenting and making publicly available the information it

has received so that interested parties may evaluate these data for

themselves and use it as guidance if they choose to use nPB until a

proposal and final rule are in place. EPA is also interested in

receiving additional information on human health and toxicological

risks associated with exposure to nPB. As EPA receives new data, they

will be added to the docket, along with notice of data availability in

the Federal Register, as appropriate.

D. Potential Use

EPA is requesting information on the anticipated uses for nPB, the

extent of its use in the different sectors (aerosols, solvents,

adhesives, coatings, and inks), as well as estimated market potential.

The Agency is also requesting information on the relative effectiveness

of nPB versus the chemicals it would potentially replace, and the

relative quantities of nPB that would be needed in various sectors

compared to other chemicals that it would potentially replace. This

information will provide the Agency information needed to assess

potential environmental effects associated with use of nPB.

IV. Regulatory Options

EPA believes that notice-and-comment rulemaking is required to

place any alternative on the list of prohibited substitutes, to list a

substitute as acceptable only under certain use conditions or narrowed

use limits, or to remove an alternative from either the list of

prohibited or acceptable substitutes.

EPA does not believe that rulemaking procedures are required to

list alternatives as acceptable with no limitations. Such listings do

not impose any sanction, nor do they remove any prior license to use a

substitute. Consequently, EPA adds substitutes to the list of

acceptable alternatives without first requesting comment on new

listings. Updates to the acceptable and pending lists are published as

separate Notices of Acceptability in the Federal Register.

V. References

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from 1-halogenpropanes in the rat. Biochem J 100:362-372.

Barnsely, E; Grenby, T; Young, L. 1966. Biochemical Studies of Toxic

Agents: the metabolism of 1- and 2-bromopropane in rats. Biochem J

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Bors, W; Michel, C; Dalke, C; Stettmaier, K; Saran, M; Andrae, U.

1993. Radical intermediates during the oxidation of nitropropanes.

The formation of NO2 from 2-nitropropane, its reactivity

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nitropropane. Chemical Research in Toxicology 6:302-309.

ClinTrials. 1997a. A 28-Day Inhalation Study of a Vapor-Formulation

of ALBTA1 in the Albino Rat. Report No. 91189. Prepared by

ClinTrials BioResearch Laboratories, Ltd., Senneville, Quebec,

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Rouge, LA.

ClinTrials. 1997b. ALBTA1: A 13-Week Inhalation Study of a Vapor

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Elf Atochem S.A. 1993. Acute Oral Toxicity in Rats. N-Propyl

Bromide. Study No. 10611 Tar. Study Director, Jack Clouzeau. Study

performed by Centre International de Toxicologie, Miserey, France.

November 3, 1993.

Elf Atochem S.A. 1994. Ames test--reverse mutation assay on

Salmonella typhimurium. n-Propyl Bromide. HIS1005/1005A. Study

performed by Sanofi Recherche, Service de Toxicologie.

Elf Atochem S.A. 1995a. Micronucleus Test by Intraperitoneal Route

in Mice. N-Propyl Bromide. Study No. 12122 MAS. Study Director,

Brigitte Molinier. Study performed by Centre International de

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Elf Atochem S.A. 1995b. Acute Dermal Toxicity in Rats. N-Propyl

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Elf Atochem S.A. 1995c. Skin Sensitization Test in Guinea-Pigs

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maximum tolerated dose and study sensitivity for detecting rodent

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0147, Work Assignment No. 0-13 (January 16, 1996).

[[Page 8047]]

ICF. 1996b. ``Estimated ODPs for Brominated Compounds.'' Memorandum

prepared by ICF Incorporated, Washington, DC, for EPA, under

Contract No. 68-D5-0147, Work Assignment No. 1-11 (October 2, 1996).

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Memorandum prepared by ICF Incorporated, Washington, DC, for EPA

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Limit for N-Propyl-Bromide'.'' Memorandum prepared by Dr. Elizabeth

Weisburger under subcontract with ICF Incorporated, Washington, DC,

for EPA, under Contract No. 68-D5-0147, Work Assignment No. 1-11

(July 16, 1997).

ICF. 1998c. ``Review of Japanese Study on 1-Bromopropane and 2-

Bromopropane.'' Memorandum prepared by ICF Incorporated, Washington,

DC, for EPA, under Contract No. 68-D5-0147, Work Assignment No. 2-09

(February 16, 1998).

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N-Propyl Bromide.'' Memorandum prepared by ICF Incorporated,

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Bromide.'' Memorandum prepared by ICF Incorporated, Washington, DC,

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(April 30, 1998).

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Bromide.'' Memorandum prepared by ICF Incorporated, Washington, DC,

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(September 24, 1998).

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Loveday, K; Lugo, M; Resnick, M; Anderson, B; Zeiger, E. 1989.

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beta-amyloid protein in mouse brain comparison between young mouse

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Perocco, P; Bolognesi, S; Alberghini, W. 1983. Toxic activity of

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Roscher, E; Kyriakoula Z-S; Andrae, U. 1990. Involvement of

different pathways in the genotoxicity of nitropropanes in cultured

mammalian cells. Mutagenesis 5(4):375-380.

Rosenkranz, H; Klopman, G. 1990. Prediction of the carcinogenicity

in rodents of chemicals currently being tested by the US National

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5(5):425-432.

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in press.

[[Page 8048]]

Dated: February 10, 1999.

Carol M. Browner,

Administrator.

[FR Doc. 99-3993 Filed 2-17-99; 8:45 am]

BILLING CODE 6560-50-P