[Federal Register Volume 59, Number 192 (Wednesday, October 5, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-24642]


[[Page Unknown]]

[Federal Register: October 5, 1994]


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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 51

[FRL-5082-2]

 

Air Quality: Revision to Definition of Volatile Organic 
Compounds--Exclusion of Volatile Methyl Siloxanes and 
Parachlorobenzotrifluoride

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This action revises EPA's definition of volatile organic 
compounds (VOC) for purposes of preparing State implementation plans 
(SIP's) to attain the national ambient air quality standards (NAAQS) 
for ozone under title I of the Clean Air Act (Act) and for the Federal 
implementation plan (FIP) for the Chicago ozone nonattainment area. 
This revision adds parachlorobenzotrifluoride (PCBTF) and volatile 
methyl siloxanes (VMS) to the list of compounds excluded from the 
definition of VOC on the basis that these compounds have negligible 
contribution to tropospheric ozone formation.

EFFECTIVE DATES: This final action will be effective on December 5, 
1994 unless notice is received by November 4, 1994 that someone wishes 
to submit adverse or critical comments or request a public hearing. If 
the effective date is delayed for this action due to the need to 
provide for public comment, timely notice will be published in the 
Federal Register.

ADDRESSES: Comments should be submitted in duplicate (if possible) to: 
Air and Radiation Docket and Information Center (6102), Attention: 
Docket No. A-93-47, U.S. Environmental Protection Agency, 401 M Street, 
SW, Washington, DC 20460. Comments should be strictly limited to the 
subject matter of this rule, the scope of which is discussed below.
    Public Hearing: If anyone contacts EPA requesting a public hearing, 
it will be held at Research Triangle Park, North Carolina. Persons 
wishing to request a public hearing, wanting to attend the hearing or 
wishing to present oral testimony should notify Mr. William Johnson, 
Air Quality Management Division (MD-15), U.S. Environmental Protection 
Agency, Research Triangle Park, North Carolina 27711, telephone (919) 
541-5245. The EPA will publish notice of a hearing, if a hearing is 
requested, in the Federal Register. Any hearing will be strictly 
limited to the subject matter of the rule, the scope of which is 
discussed below.
    This action is subject to the procedural requirements of section 
307(d)(1)(B), (J), and (U) of the Act, and 42 U.S.C. 7607(d)(1)(B), 
(J), and (U). Therefore, EPA has established a public docket for this 
action, A-93-47, which is available for public inspection and copying 
between 8 a.m. and 4 p.m., Monday through Friday, at EPA's Air and 
Radiation Docket and Information Center, Room M-1500, 401 M Street, SW, 
Washington, DC 20460. A reasonable fee may be charged for copying.

FOR FURTHER INFORMATION CONTACT: William Johnson, Office of Air Quality 
Planning and Standards, Air Quality Management Division (MD-15), 
Research Triangle Park, NC 27711, phone (919) 541-5245.

SUPPLEMENTARY INFORMATION:

I. Background

    On September 28, 1992, the Occidental Chemical Corporation (also 
known as OxyChem) petitioned EPA to take all necessary and appropriate 
action to exclude parachlorobenzotrifluoride (also known as 4-
chlorobenzotrifluoride, PCBTF, C7H4F3Cl (CAS number 98-
56-6)) from regulation as a precursor to tropospheric ozone. In support 
of their petition, Occidental Chemical Company submitted two reports: 
``Loss Processes for 4-Chlorobenzotrifluoride Under Atmospheric 
Conditions,'' by Roger Atkinson, Sara M. Aschmann, Arthur M. Winer and 
James N. Pitts, Jr., University of California at Riverside, October 
1984; and ``Tropospheric Lifetime Estimates for Several Aromatic 
Compounds,'' by David Nelson and Robert Brown, Aerodyne Research, Inc., 
May 1992. In addition, Occidental Chemical Company submitted a copy of 
an October 18, 1985 Federal Register notice (50 FR 42216) which 
announced a decision by EPA not to require further testing of 
parachlorobenzotrifluoride for health effects, environmental effects, 
and chemical fate under the Toxic Substances Control Act.
    On December 11, 1992, Dow Corning Corporation petitioned EPA to 
take several actions that would have the effect of exempting VMS under 
the Act as precursors to tropospheric ozone. The VMS are organic 
compounds whose basic molecular structure is built on a backbone of 
alternating silicon and oxygen atoms, formed into either a ring or 
linear chain containing from two to seven silicon atoms. Methyl groups 
(and no other functional groups, as defined here) are attached to this 
central backbone, their numbers varying with the size and shape of the 
molecule. Compounds covered by the designation VMS in this proposal are 
cyclic, branched, or linear, completely methylated siloxanes, including 
the compounds listed in Table 1. Symbols shown in the table, such as MM 
and D4, are commonly accepted abbreviations for the longer 
chemical name shown beside each.

                                      Table 1.--Volatile Methyl Siloxanes                                       
----------------------------------------------------------------------------------------------------------------
        CAS No.                                    Chemical name                                  Formula       
----------------------------------------------------------------------------------------------------------------
Linear VMS:                                                                                                     
    107-45-0............  Hexamethyldisiloxane (MM).......................................  C6H18OSi2           
    107-51-7............  Octamethyltrisiloxane (MDM).....................................  C8H24O2Si3          
    141-62-8............  Decamethyltetrasiloxane (MD2M)..................................  C10H30O3Si4         
    141-63-9............  Dodecamethylpentasiloxane (MD3M)................................  C12H36O4Si5         
    107-63-9............  Tetradecamethylhexasiloxane (MD4M)..............................  C14H42O5Si6         
    63148-62-9..........  Dimethyl silicones and siloxanes (MDxM).........................                      
Cyclic VMS:                                                                                                     
    541-05-9............  Hexamethylcyclotrisiloxane (D3).................................  C6H18O3Si3          
    556-67-2............  Octamethylcyclotetrasiloxane (D4)...............................  C8H24O4Si4          
    541-02-6............  Decamethylcyclopentasiloxane (D5)...............................  C10H30O5Si5         
    540-97-6............  Dodecamethylcyclohexasiloxane (D6)..............................  C12H36O6Si6         
    69430-24-6..........  Cyclopolydimethylsiloxanes (Dx).................................                      
Branched VMS:                                                                                                   
    17928-28-8..........  1,1,1,3,5,5,5-Heptamethyl-3-[(trimethylsilyl)oxyl]-trisiloxane    C10H30O3Si4         
                           (M3T).                                                                               
    3555-47-3...........  1,1,1,5,5,5-Hexamethyl-3,3,bis[(trimethylsilyl)oxy]-trisiloxane   C12H36O4Si5         
                           (M4Q).                                                                               
                          Pentamethyl[(trimethylsilyl)oxy]cyclotrisiloxane (MD3)..........  C8H24O4Si4          
----------------------------------------------------------------------------------------------------------------

    Based on the results of reactivity studies demonstrating that VMS 
do not contribute to tropospheric ozone formation, Dow Corning 
Corporation requested that EPA do the following:
    1. Amend EPA's general regulatory definition of VOC appearing in 40 
CFR 51.100(s) (see 57 FR 3945, February 3, 1992) so as expressly to 
exclude VMS from the term ``VOC'' by final regulatory action.
    2. In taking action on any currently-pending or future proposal to 
approve State VOC regulations as part of a SIP, clarify that EPA lacks 
authority to approve or enforce VOC regulations to the extent that they 
apply to VMS or otherwise regulate VMS as precursors to tropospheric 
ozone.
    3. In taking any future proposed or final regulatory action to 
amend or promulgate VOC regulations for the purpose of reducing 
tropospheric ozone (e.g., any action pursuant to section 183(e) of the 
Act to control VOC in consumer and commercial products), take such 
action and make such statements as may be necessary to ensure that such 
regulations will not apply to VMS.
    4. Take such other actions and make such other statements as may be 
necessary to implement the exemption of VMS from regulation as 
precursors to tropospheric ozone.
    In support of its requests, Dow Corning submitted supporting 
information and documentation to demonstrate that VMS:
    1. Do not contribute to the formation of tropospheric ozone, and in 
some situations inhibit the formation of tropospheric ozone;
    2. Do not deplete stratospheric ozone;
    3. Are generally nontoxic to humans and the environment;
    4. Are used in personal care products and other consumer products;
    5. Have potential uses as substitutes for chlorofluorocarbons in a 
number of specified applications; and,
    6. Have a wide variety of applications and potential applications 
as substitutes for other VOC.
    The petition included a number of reports on smog chamber 
reactivity studies on VMS and other supporting information. A copy of 
this material is included in the docket for this rulemaking.
    Several toxicity studies for multiple routes of exposure exist for 
parachlorobenzotrifluoride. In laboratory animals, kidney and liver 
effects have been documented. More importantly, eye and nasal 
irritation were observed during inhalation exposures. However, it is 
not expected to have ecological effects. There is a lack of data 
concerning carcinogenicity in humans and animals. Of the volatile 
methyl siloxanes, only the D4 has been studied extensively. Mild liver 
effects (inhalation exposure) and testicular effects (dietary exposure) 
were observed in laboratory animals. The D4 compound is known to 
produce adverse immunological effects when injected, but it is not 
known if the same effect can be elicited by inhalation exposure. These 
compounds are not included on the 112(b)(1) list of hazardous air 
pollutants and are not regulated by any program. Our best judgment at 
this time is that the known toxic effects of the pollutants do not 
warrant alteration of a decision to remove them from the VOC list nor 
warrant addition to the 112(b)(1) list. If additional data were to 
alter this judgment, or if petitioned, the Agency would further 
consider the need to add either or both compounds to 112(b)(1).
    If VMS and PCBTF are accepted as having negligible photochemical 
reactivity, exempting them from regulation as ozone precursors could 
contribute to the achievement of several important environmental goals. 
For example, they might be used as a substitute for several compounds 
(e.g., methyl chloroform) that are listed as hazardous air pollutants 
(HAP) under section 112 of the Act.
    Another area of concern is finding substitutes for ozone depleting 
substances (ODS) which are active in depleting the stratospheric ozone 
layer. Under the London Amendments to the Montreal Protocol on 
substances that deplete the ozone layer (``Montreal Protocol''), the 
United States agree to phase out production and consumption of certain 
chlorofluorocarbons (CFC) by the year 2000 and methyl chloroform by 
2005 (see 58 FR 15016 (March 18, 1993)). In 1990, Congress added title 
VI to the Act in part to provide for the implementation of this 
phaseout (see 42 U.S.C. Sec. 7671 et seq.). The 1990 Amendments 
specified an initial list of Class I and Class II ODS, authorizing EPA 
to add compounds to both lists depending on a given compound's 
potential to contribute to stratospheric ozone depletion, (Id. 7671a.) 
The 1990 Amendments further required phaseout of the production and 
consumption of Class I ODS by 2000, methyl chloroform by 2002, and 
Class II ODS by 2030 (see 42 U.S.C. 7671c, 7671d). At the fourth 
meeting, in 1992, of the parties to the Montreal Protocol in 
Copenhagen, Denmark, the parties adjusted the phaseout schedules of 
Class I substances under the Montreal Protocol to phase out Class I CFC 
and methyl chloroform by 1996. In 1993, EPA proposed to accelerate the 
phaseout of Class I CFC and methyl chloroform in order to discontinue 
use of these compounds after January 1, 1996 (see 58 FR 15022).
    As a result of these phaseout deadlines, there is a need to develop 
substitutes for ODS. The EPA has listed several VMS compounds as ozone-
depleting substance substitutes under the program known as the 
``Significant New Alternatives Policy'' (SNAP) program, (59 FR 13044, 
March 18, 1994). Within the context of the SNAP rule, substitutes are 
``acceptable'' if they are technically feasible to be used as an 
alternative to an ODS for particular uses and give reduced overall risk 
to human health and the environment compared to the ODS they replace. 
In the SNAP rule, EPA listed several volatile siloxanes as acceptable 
substitutes for metal cleaning, electronics cleaning, and precision 
cleaning (59 FR 13134). The SNAP program lists benzotrifluorides as 
``pending decisions'' for use in aerosols and adhesives, coatings, and 
inks (59 FR 13145). The Agency has not yet completed reviews of data 
for these benzotrifluoride compounds, but plans to issue a SNAP 
determination for these substitutes in the next set of listing 
decisions (59 FR 13118).
    In these areas of concern, toxic air emissions and depletion of 
stratospheric ozone, adding these compounds to the list of negligibly-
reactive VOC may provide support for the EPA's pollution prevention 
efforts. By enacting the Pollution Prevention Act of 1990, Congress 
established as a national policy that ``pollution should be prevented 
or reduced at the source whenever feasible'' (42 U.S.C. 13). An 
important part of EPA's pollution prevention strategy is encouraging 
companies to use substitutes in their production processes that are 
more environmentally benign than the substances they currently use. For 
example, in its blueprint for a comprehensive national pollution 
prevention strategy, (56 FR 7849 (February 26, 1991)), the EPA 
recognized that the definition of pollution prevention includes a 
``switch to non-toxic or less toxic substitutes'' (Id. at 7854).

II. The EPA Response to the Petitions

    The EPA is responding to these petitions by taking action in this 
notice to add PCBTF and VMS to the list of compounds appearing in 40 
CFR 51.100(s) that are excluded from the definition of VOC. By this 
final action, PCBTF and VMS are excluded from the VOC definition.
    The EPA's conclusions concerning the exclusion of PCBTF are based 
on the report ``Loss Processes For 4-Chlorobenzotrifluoride Under 
Atmospheric Conditions,'' by Roger Atkinson et al. (University of 
California/Riverside), October 1984. This report along with other 
information was submitted by Occidental Chemical Corporation and has 
been placed in the docket for this action.
    The Atkinson et al. report indicated that the kOH reactivity 
of PCBTF (2.3 x 10-13cm3 molecule-1 sec-1) is 
somewhat lower than, but statistically indistinguishable from, that of 
ethane (2.7 x 10-13cm3 molecule-1 sec-1). Ethane is 
currently the most reactive of the compounds currently excluded as VOC 
due to negligible photochemical reactivity. It is conceivable, however, 
that there are other processes, e.g., photodissociation, reaction with 
ozone or with nitrogen trioxide (NO3) radicals, that might enhance 
the ozone-forming reactivity of PCBTF. Atkinson et al. explored to some 
extent these possibilities by studying experimentally the 
photodissociation of PCBTF and its reaction with ozone. They found a 
negligibly low rate of reaction with ozone and no measurable photolysis 
of PCBTF. The photolysis detection limit, however, was 2.7 x 10-6 
sec-1, which is a rate somewhat higher than that of the reaction 
rate with hydroxyl radicals (OH) in typical mid-day urban atmospheres 
(1.4 x 10-6 sec-1). Thus, significant, though nonmeasurable, 
photodissociation of PCBTF in the atmosphere cannot be precluded. On 
the other hand, it is not known whether dissociation, even if it does 
occur, would enhance the ozone-forming reactivity of PCBTF. In the 
absence of measurable photodissociation, Atkinson et al. could not 
obtain evidence on the nature and follow-up chemistry of the 
photodissociation products.
    In summary, the evidence available indicates that: (1) The kOH 
reactivity of PCBTF is not higher than that of ethane, and (2) there is 
no evidence of processes (other than reaction with OH) that might 
increase the ozone-forming reactivity above that of ethane.
    The EPA's decision concerning the exclusion of VMS as VOC is based 
on the following: ``Investigation of the Ozone Formation Potential of 
Selected Volatile Silicone Compounds,'' by William P. L. Carter et al. 
(University of California/Riverside), November 1992; ``Determination of 
the Atmospheric Lifetimes of Organosilicon Compounds,'' by Roger 
Atkinson et al. (University of California/Riverside), September 1990; 
and ``Kinetics of the Gas Phase Reactions of a Series of Organosilicon 
Compounds with OH and NO3 Radicals and O3 at 
2972K,'' by R. Atkinson et al. (Environmental Science & 
Technology, 25, p.863, 1991). These reports were submitted, along with 
other materials by Dow Corning, in support of its petition. This 
information has been placed in the docket for this action.
    The Atkinson et al. studies indicated that volatile methyl 
siloxanes have kOH reactivities higher than that of ethane, and 
suggested that follow-up smog chamber studies should be conducted to 
determine their ozone-forming potentials. Such a chamber study is the 
subject of the Carter et al. report. Carter produced evidence for 
hexamethyldisiloxane (MM), octamethylcyclotetrasiloxane (D4), and 
decamethylcyclopentasiloxane (D5) that showed these siloxanes have 
negative ozone-forming potentials for commonly-occurring ambient 
conditions. However, the degradation pathways (mechanism) are still not 
well understood. Nevertheless, the investigators concluded that the 
ozone-forming reactivities of these siloxanes cannot be higher than 
that of ethane.

III. Final Action

    Today's final action is based on EPA's review of the material in 
Docket No. A-93-47. The EPA is publishing this action without prior 
proposal because the Agency views this as a noncontroversial amendment 
and anticipates no adverse comments. However, in a separate document in 
this Federal Register publication, the EPA is proposing to approve the 
definition revision should adverse or critical comments be filed or a 
request for a public hearing be made. The EPA hereby amends its 
definition of VOC at 40 CFR 51.100(s) to exclude PCBTF and VMS as VOC 
for ozone SIP and ozone control purposes. The revised definition will 
apply in the Chicago ozone nonattainment area pursuant to the 40 CFR 
52.741(a)(3) definition of volatile organic material or volatile 
organic compound. States are not obligated to exclude from control as a 
VOC those compounds that EPA has found to be negligibly reactive. 
However, States should not include these compounds in their VOC 
emissions inventories for determining reasonable further progress under 
the Act (e.g., section 182(b)(1)) and may not take credit for 
controlling these compounds in their ozone control strategy. Further, 
these negligibly-reactive compounds may not be used for emissions 
netting (e.g., 40 CFR 51.166(b)(2)(c)), offsetting (40 CFR appendix S), 
or trading with reactive VOC (Emissions Trading Policy Statement, 51 FR 
43814, December 4, 1986 and Economic Incentive Program Rules, 59 FR 
16690, April 7, 1994).
    In addition, corrections are made to the names of three compounds 
which have previously been exempted from the definition of VOC: 1,1,1-
trichloro-2,2,2-trifluoroethane (CFC-113) is changed to 1,1,2-
trichloro-1,2,2-trifluoroethane (CFC-113); chlorodifluoromethane (CFC-
22) is changed to chlorodifluoromethane (HCFC-22); and trifluoromethane 
(FC-23) is changed to trifluoromethane (HFC-23). These changes are 
corrections to nomenclature only and are not substantive.
    Pursuant to 5 U.S.C. 605(b), I hereby certify that this action will 
not have a significant economic impact on a substantial number of small 
entities because it relaxes current regulatory requirements rather than 
imposing new ones. The EPA has determined that this rule is not 
``significant'' under the terms of Executive Order 12866 and is, 
therefore, not subject to Office of Management and Budget (OMB) review. 
This action does not contain any information collection requirements 
subject to OMB review under the Paperwork Reduction Act of 1980 (44 
U.S.C. 3501 et seq.).
    Assuming this rulemaking is subject to section 317 of the Act, the 
Administrator concludes, weighing the Agency's limited resources and 
other duties, that it is not practicable to conduct an extensive 
economic impact assessment of today's action since the rule promulgated 
today will relax current regulatory requirements. Accordingly, the 
Administrator simply notes that any costs of complying with today's 
action, any inflationary or recessionary effects of the regulation, and 
any impact on the competitive standing of small businesses, on consumer 
costs, or on energy use, will be less than or at least not more than 
the impact that existed before today's action.

List of Subjects in 40 CFR Part 51

    Administrative practice and procedure, Air pollution control, 
Carbon monoxide, Intergovernmental relations, Lead, Nitrogen dioxide, 
Ozone, Particulate matter, Reporting and recordkeeping requirements, 
Sulfur oxides, Volatile organic compounds.

    Dated: September 23, 1994.
Carol M. Browner,
Administrator.

    For reasons set forth in the preamble, part 51 of chapter I of 
title 40 of the Code of Federal Regulations is amended as follows:

PART 51--REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF 
IMPLEMENTATION PLANS

    1. The authority citation for part 51 continues to read as follows:

    Authority: 42 U.S.C. 7410(a)(2), 7475(e), 7502 (a) and (b), 
7503, 7601(a)(1) and 7620.

    2. Section 51.100 is amended by revising paragraph (s)(1) 
introductory text to read as follows:


Sec. 51.100  Definitions.

* * * * *
    (s) * * *
    (1) This includes any such organic compound other than the 
following, which have been determined to have negligible photochemical 
reactivity: methane; ethane; methylene chloride (dichloromethane); 
1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-
trifluoroethane (CFC-113); trichlorofluoromethane (CFC-11); 
dichlorodifluoromethane (CFC-12); chlorodifluoromethane (HCFC-22); 
trifluoromethane (HFC-23); 1,2-dichloro 1,1,2,2-tetrafluoroethane (CFC-
114); chloropentafluoroethane (CFC-115); 1,1,1-trifluoro 2,2-
dichloroethane (HCFC-123); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1-
dichloro 1-fluoroethane (HCFC-141b); 1-chloro 1,1-difluoroethane (HCFC 
142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124); pentafluoroethane 
(HFC-125); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1-trifluoroethane 
(HFC-143a); 1,1-difluoroethane (HFC-152a); parachlorobenzotrifluoride 
(PCBTF); cyclic, branched, or linear completely methylated siloxanes; 
and perfluorocarbon compounds which fall into these classes:
* * * * *
[FR Doc. 94-24642 Filed 10-4-94; 8:45 am]
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