[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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