[REPORT' ON .THE PROGRESS OF
REGULATIONS TO PROTECT
STRATOSPHERIC OZONE
REPORT TO CONGRESS
February 1982
tf.S. ENVIRONMENT^ 'PROTECTION AGENCY
OFFICE OF TOXIC SUBSTANCES
' 4,01 M Street-, S.swZ
Washing ton,. b.C-.
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TABLE OF CONTENTS
SUMMARY 1
I. THE OZONE DEPLETION ISSUE 4
II. THE AEROSOL RULE 9
III NONAEROSOL USES 12
IV. INTERNATIONAL PRODUCTION AND COOPERATION 14
V. FURTHER REGULATION OF CFCS 16
REFERENCES 17
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SUMMARY
As mandated by Section 155 of the Clean Air Act Amendments
of 1977, PL 95-95 (CAA), the Environmental Protection Agency
(EPA) submits to Congress this report on the progress of
regulation to protect stratospheric ozone covering tne period
from August 1979 to December 1981. Section 155 requires that the
Administrator report to Congress on actions taken by the
Environmental Protection Agency and other Federal agencies to
regulate sources of halocarbon emissions/ the results of such
regulations in protecting the ozone layer, the need for
additional regulatory action, if any, and recommendations for
control of substances, practices, processes, or activities other
than those involving halocarbons which affect stratospheric ozone
and cause or contribute to harmful effects on public health or
welfare.
This report reviews activities related to the protection of
stratospheric ozone from potential depletion due to emissions of
chlorofluorocarbons (CFCs) and other ozone-depleting
substances. If ozone concentrations are reduced, increased
amounts of solar ultraviolet radiation in the wavelength region
of 290-320 nanometers (UV-B) would reach the earth's surface.
This may have a number of consequences, including higher
incidence of nonmelanoma skin cancer among humans, decreased
plant productivity, and adverse effects on the aquatic food
chain.
In March 1978, the Food and Drug Administration (FDA) and
EPA promulgated rules that prohibited the manufacturing and
processing of CFCs for nonessential aerosol propellant uses.
Domestic CFC use as aerosol propellants was about 448 million
pounds in 1973. In 1980 aerosol uses accounted for about 24.5
million pounds out of a total of 835 million pounds produced
domestically. However, nonaerosol uses of CFC, including
solvents, blowing and insulating agents in foam manufacturing,
refrigeration, air conditioning, and other specialized processes,
increased between 1975 and 1979 and then fell slightly in the
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1979-80 economic slowdown. Anticipated recovery of the economy
combined with expected market growtn in some uses of CFCs may
eventually offset the reductions achieved by the aerosol rule.
In October 1980, EPA issued an Advance Notice of Proposed
Rulemaking (ANPR) requesting public comment about possible
effects on human health and the environment from the continuing
use of CFCs, and on the economic aspects of the issue. The ANPR
solicited comments on the validity of the ozone depletion theory,
and the effectiveness of restricting the use of CFCs as a means
of dealing with any significant problem. Also in 1980, EPA
issued a proposed rule under authority of Part A of the CAA
Amendments of 1977 which would regulate emissions of certain
solvents including CFC-113 and other substances which may deplete
ozone from new, modified, or reconstructed organic solvent
cleaners. EPA is currently studying whether to include these
degreasing solvents in a final rule.
In addition to CFCs, other potential ozone depleting
substances are being investigated by EPA and other agencies. For
example, EPA recently completed an analysis of production and
emissions of methyl chloroform. Other agencies, including the
National Aeronautics and Space Administration, the National
Oceanic and Atmospheric Administration, the Federal Aviation
Administration, and the Department of Energy, are investigating
the effects on stratospheric ozone of compounds other than CFCs,
including other halocarbons, carbon dioxide, and nitrogen oxides.
Because CFC emissions in any country may be dispersed
throughout the earth's atmosphere, the protection of
stratospheric ozone is an international issue. A few countries
have prohibited most aerosol propellant uses and many CFC-
producing and using nations have achieved reductions in aerosol
propellant uses by regulatory or voluntary actions. Several
nations are assessing the feasibility of reducing emissions from
other uses. Japan and the European Economic Community have
limited CFC-11 and CFC-12 production capacity to present
levels. The~U~.S. is participating in a number of international
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organizations which promote/ coordinate, and assess research and
study technical and economic aspects of the CFG/ozone depletion
issue.
To fulfill the requirements of the CAA Amendments of 1977
and to improve and expand the scientific basis for evaluating"the
necessity of further reductions in CFG emissions, EPA and other
Federal agencies are continuing to monitor and support research
related to improving our understanding of atmospheric science,
adverse health and environmental consequences of ozone depletion,
technological capabilities for limiting CFG emissions from major
sources, and the costs of achieving such controls. Any decision
regarding EPA action would be based on an evaluation of all these
factors.
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I. THE OZONE DEPLETION ISSUE
Ozone is found throughout the stratosphere, which is 10 to
50 kilometers above the earth's surface. Ozone is important
because it limits the amount of solar ultraviolet radiation
reaching the earth, specifically in the wavelength region of 290-
320 nanometers (UV-B), which has been correlated to acute effects
(e.g., sunburn) and nonmelanoma skin cancer among certain human
populations. The concentration of ozone present in the
stratosphere is determined by a dynamic balance between natural
processes that produce and destroy ozone. Based on theoretical
atmospheric models, it is postulated that the rate of ozone
destruction and creation can be altered by a buildup in the
stratosphere of several chemical species including species
containing chlorine (e.g., Cl, CIO), hydrogen (e.g., HO, HO.,,
H2°2^' and nitr°9en (e.g., NO, N0x).
In view of the screening function of the ozone layer, any
significant increase in the rate at which chlorine species are
injected into the stratosphere is of concern because chlorine
atoms and chlorine oxide act as catalysts in chemical reactions
that destroy ozone. Chlorofluorocarbons (CFCs)* are very stable
in the lower atmosphere. They migrate very slowly from" the
troposphere across the tropopause and into the stratosphere where
they are decomposed by solar ultraviolet radiation and release
free chlorine. Consequently, the continued worldwide release of
CFCs has the potential to increase chlorine concentrations in the
stratosphere, resulting in decreased stratospheric ozone.
Increases in chlorine concentrations in the stratosphere have
been measured; however, to date, changes in ozone in the
Chlorofluorocarbons are a family of chemicals. Historically,
CFC-11 and CFC-12 have accounted for about 90 percent of
worldwide CFC production. Other commercially important CFCs
include CFC-113, CFC-114, CFC-115, and a related compound,
CFC-22, which contains hydrogen.
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stratosphere beyond natural variations have neither been measured
nor expected based on model calculations.
Scientists have developed necessarily simplified atmospheric
models (computer simulations) of the complex chemical, transport,
and radiative processes in the atmosphere to describe and predict
potential stratospheric changes. These models are limited by tne
quality and extent of data on actual atmospheric levels of the
species of interest.
A Workshop on the Stratosphere sponsored by the National
Aeronautics and Space Administration (NASA) and the World
Meteorological Organization (WHO') was held in May 1981. At the
workshop, scientists reported on computer model results, using
the most recent chemical reaction rate data (derived from
laboratory experiments). Present central estimates of their
various computer model calculations are that continued emissions
at present levels of CFC-11 and CFC-12 may eventually result in
"steady-state" ozone depletion of 5-10 percent. In other words.
assuming world CFC emissions continued at present levels into the
future, current models show that the existing balance between
ozone-creating and ozone-destroying processes in the stratosphere
would be changed in such a way that a new equilibrium, or
"steady-state", would be achieved near the end of the 2~lst
century and that the total amount of stratospheric ozone would be
90-95 percent of what it is today. If other halocarbons at their
present emission rates are included in the models, the "steady-
state" depletion is calculated to increase by a third (e.g., a
calculated "steady-state" depletion of 6 percent for CFC-11 and
CFC-12 would increase to 8 percent when other halocarbons are
considered). Workshop participants noted that substantial
uncertainty remains with respect to some atmospheric chemical
reactions. The final report from this workshop was issued in
February 1982.
The models have also been used to estimate the globally-
averaged depletion of stratospheric ozone that may have occurred
to date due to CFCs; these estimates show it to be less than 1
percent. Using these models, the 5 to 10 percent "steady-state"
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depletion calculations imply that continued emissions of CFC-11
and CFC-12 at current levels are calculated to result in an ozone
depletion rate of less than about 0.1 percent per year. If this
rate of change is correct, taking the time for additional and
improved measurements of stratospheric ozone and for the
development of other information may not result in significant
incremental risk.
Statistical analysis of data from ground monitoring
stations, known as ozone trend analysis, is done to detect trends
in total global ozone. This analysis indicates the absence of
any statistically significant trend in total global ozone over
the last decade. This result is not inconsistent with
atmospheric model calculations. A recent assessment indicates
that the current network of ground-based monitoring stations may
be sensitive enough to detect as little as a 2-4 percent change
per decade in total ozone.
In addition to CFCs, scientists are investigating other
chemical substances including methyl chloroform, nitrogen oxides,
and carbon dioxide (CG>2) for their effects on ozone.
EPA has completed an analysis of production and emissions of
methyl chloroform. Domestic production was 625 million pounds
in 1978, increasing at an average of 16 percent annually between
1974 and 1978. Worldwide production totalled 1.05 billion pounds
in 1978, increasing at about a 30 percent annual"rate between
1974 and 1978. Analysis of the relative ozone depletion
potential of various substances by Lawrence Livermore National
Laboratory modeling studies indicates that methyl chloroform has,
on a pound per pound basis, about one-seventh (0.14) the
potential of CFC-11 for depleting stratospheric ozone. Methyl
chloroform is presently included in a proposed EPA rule that
would limit emissions of certain degreaser substances from new,
modified, and reconstructed organic solvent cleaners.4
Nitrogen oxide emissions from aircraft flying at high
altitudes (either upper troposphere or lower stratosphere) and
carbon dioxide-also may affect stratospheric ozone. Atmospheric
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raodel calculations indicate that nitrogen oxides released by
subsonic aircraft exhausts in the region of the tropopause may
already have increased ozone concentrations by between 0.5 and
1.0 percent. However, as aircraft operate at higher altitudes
injecting nitrogen oxides directly in the lower stratosphere, • the
effect may be to decrease ozone in that region. Significant
increases in the number of flights or flight altitudes may be
necessary before significant ozone changes would occur.
Increases in carbon dioxide in the atmosphere, due primarily
to increased burning of fossil fuels, are expected to lead to
decreases in stratospheric temperatures. The consequent slowing
of chemical reactions taking place in the stratosphere could make
the impact of CFCs on stratospheric ozone less than would
otherwise occur without a change in stratospheric temperature. A
carbon dioxide buildup may also result in global surface
temperature increases and climatic changes of unknown
variations.
Although scientists have made great progress in
understanding complex stratospheric processes through modeling,
laboratory experiments, and atmospheric monitoring, substantial
work remains to decrease scientific uncertainties.
A decrease in ozone, independent of other factors, increases
the intensity of UV-B reaching the earth's surface. Scientists
agree that increased UV-B levels at the earth's surface would
t
increase the incidence of human nonmelanoma skin, cancer,
especially among light-skinned people. Nonmelanoma skin cancer
is a problem primarily because it causes disfigurement and
imposes economic burdens associated with its treatment. If
detected early, it is usually treatable.
Although the relationship between malignant melanoma, a
dangerous form of skin cancer, and UV-B exposure has been studied
for over two decades, a dose-response relationship has not been
established. For melanoma, total accumulated UV-B dose does not
appear to be a significant causal factor, although acute or
repeated exposures to sunlight may be important.6 Melanomas are
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increasing at a faster rate than most other cancers especially
among younger, more affluent, and better educated persons;
however, the relationship between UV-B exposure and melanoma is
not known.
Information on nonhuman effects of increased UV-B is
presently difficult to quantify. EPA is funding a three-year
field research study (through 1983) to determine the effects of
increased UV-B on selected economically important crops grown
under otherwise normal conditions. Nonagricultural terrestrial
organisms have been shown to be susceptible to increases in UV-B
exposure. Laboratory studies show that a number of aquatic
species (algae, plankton, fish larvae) which exist close to the
surface may be living close to their UV tolerance levels. EPA
has funded research over the last three years which has provided
excellent data on UV-B penetration many meters below the surface
in a variety of water conditions.
More detailed information on scientific issues related to
stratospheric ozone will be contained in EPA's biennial report to
the appropriate House and Senate committees on the results of
studies and research conducted by EPA and other agencies. That
report, required by Section 153(g) of the CAA Amendments of 1977,
is expected to be issued later this year.
To provide for an independent review of "the state of
knowledge of the impact of man's activities on stratospheric
ozone and effects of changes thereto, EPA has requested the
National Academy of Sciences (NAS) to consider the most recent
scientific developments and to reassess the status of the ozone
depletion theory, measurements of ozone and trace contaminant
concentrations, and health and environmental effects. A draft
report of the NASA/WHO May 1981 workshop along with other
requested reports and materials has been made available to NAS
for use in their overall assessment of the issue. The EPA
contract with NAS requires a report in December 1981, but EPA has
modified the contract to assure that NAS has adequate additional
time to provide a thorough assessment. The report is now
expected in March 1982.
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II. THE AEROSOL RULE
In 1978, EPA and FDA simultaneously published rules
prohibiting the use of CFC aerosol propellants in nonessential
Q
applications. The final EPA rule prohibited the manufacture-of
fully halogenated chlorofluoroalkanes for nonessential aerosol
propellant uses after October 15, 1978. In addition, the rule
prohibited after December 15, 1978 the processing and
distribution of bulk CFCs in commerce, the processing for export,
and the importation in bulk for aerosol propellant uses or as a
propellant in nonessential aerosol articles.
Under the Federal Food, Drug, and Cosmetic Act, FDA
prohibited the manufacture or packaging of food, drugs, medical
devices, and cosmetic products containing fully halogenated
chlorofluoroalkanes as an aerosol propellant after December 15,
1978, and the initial introduction into interstate commerce of
finisned food, drugs, medical devices, and cosmetic products
containing these substances after April 15, 1979. The FDA rule
exempted certain drugs and food products.
In its rule, EPA exempted certain uses determined to be
essential on the basis of criteria contained in a support
document for the rule. These criteria included the availability
of substitutes, the economic significance of the product, the
environmental and health impacts of the aerosol product and its
substitutes, and the effect on the quality of life if the product
or a reasonable substitute were unavailable. Current exemptions
to the EPA rule include CFC aerosol propellant applications in
conjunction with mining, aircraft operation, national defense,
pesticide use, manufacture and servicing of electrical and
electronic equipment, and mold release agents. The exemption for
mold release-agents included spinnerette release-agents which are
used in the production of manmade fibers. In January 1981, EPA
promulgated a rule, effective March 1982, revoking the
spinnerette exemption.1 Based on new information submitted to
the Agency indicating that substitutes for all uses will not be
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available by the effective date, EPA restored the exemption. In
a recent action, EPA granted a temporary exemption for the use of
CFCs in automatic pesticide dispensing units for long-term
storage of flue-cured tobacco, - pending a review of a request
for a permanent exemption. EPA has also exempted rotary-tablet
press-punch lubricants from the rule.12 Several applications for
exemptions have been denied, including CFC use in fog machines
and spray adhesives. 3 EPA is reviewing applications to exempt
CFC propellant use in nozzle shield lubricants for inert-gas
welding-guns, graphite solid lubricants, and crack detectors for
nuclear power plants*
Manufacturers and processors are required to submit annual
reports to EPA if they are manufacturing or using CFC propellants
for exempted aerosol products. In 1981, EPA's Office of
Enforcement has preliminarily reviewed reports from five
manufacturers and 45 processors for the calendar year 1980. Data
from the reports indicate that aerosol products accounted for
about 24.5 million pounds of CFCs in 1980. In comparison,
aerosol use accounted for about 448 million pounds of CFCs in
1973.14
A study is being conducted for EPA to evaluate the economic
impact of the ban on nonessential CFC aerosol propellants.
Preliminary results indicate that, in general", the impact on
consumers was small as good substitutes were readily available,
often at lower cost to the consumer. There appeared to be a
negative impact on profits, especially on CFC manufacturers and
on small, aerosol fillers. There was also a one-time cost for
aerosol product manufacturers and fillers to reformulate and
convert to hydrocarbon or carbon dioxide propelled products. 5
On December 16, 1980, EPA published an interpretive rule,
under authority of Section 12(b) of TSCA, requiring individuals
to notify EPA of exports or expected exports rf substances
regulated under Secti n 6 of TSCA. ° Th« rul< I requires
individuals to notify EPA of the first shipment of each year to a
given country.- EPA in turn will notify the importing countries
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of the export of CFCs to that country and the nature of the EPA
regulations. Since January 1981, EPA has received reports from
37 companies giving notice of export to approximately 94
countries. These exports include bulk shipments of CFCs and CFCs
in mixtures such as in exempted aerosol products.
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III. NONAEROSOL USES
Domestic CFC production and use has changed in tne last
decade. In the U.S., a sharp drop in CFC production followed a
peak of about 1.1 billion pounds in 1974.14 1980 production of
about 835 million pounds nearly equalled the 1979 domestic output
of about 838 million pounds. Since 1974, there has been a
decrease in aerosol propellant uses of CFCs from over 400 million
pounds to about 24.5 million pounds in 1980. This decrease in
CFC production for aerosol uses has been accompanied by an
increase in nonaerosol uses. Nonaerosol uses grew about
9 percent annually from 1975 to 1979 and then fell slightly in
the 1979-80 economic slowdown. 4/17 Anticipated recovery of the
economy combined with expected market growth in the use of CFCs
for solvents, food freezing, and other applications may lead to
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an increase in production over the 1974 peak. °
Concern about expected growth in nonaerosol uses, combined
with the conclusions of the 1979 NAS report, prompted EPA to
consider the need for further Agency action to control CFC
emissions. EPA published an Advance Notice of Proposed
Rulemaking (ANPR) in October 1980.19 The objective of the ANPR
was to notify the public that EPA was requesting comment about
possible effects on human health and the environment resulting
from continued use of CFCs and on the economic aspects of the
issue. The ANPR served as a tool to gather information from the
public on the validity of the ozone depletion theory and other
scientific issues, the effectiveness of restricting the use of
CFCs as a means of dealing with any significant problem, and
international aspects of the issue. The Agency was particularly
interested in gathering information on economic impacts and the
concerns of small businesses.
EPA received over 2,000 comments on the ANPR. From these
comments, it is clear that many segments of industry consider
regulatory action to be unnecessary at this time and the
regulatory strategies discussed in the ANPR to be
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controversial. The Agency believes that many of the issues
raised in these comments deserve further analysis. The quality
of the comments indicates that the ANPR has succeeded in
promoting informed public participation in the evaluation of the
issues and an exchange of information among government, industry,
and other interested parties.
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IV. INTERNATIONAL PRODUCTION AND COOPERATION
Worldwide production of CFC-11 and CFC-12 peaked in 1973-
1974. As in the U.S., there was a significant drop in worldwide
aerosol use in recent years but growth continued in nonaerosol
uses. In 1979, the member nations of the European Economic
Community (EEC) accounted for 34.0 percent of total world sales
of CFC-11 and CFC-12, the U.S. accounted for 25.5 percent, and
the rest of the world totalled 40.5 percent.20
Many CFC producing and using nations have taken steps to
reduce CFC emissions. The ten members of tne EEC are required by
an EEC Council decision to cap production capacity for CFC-11 and
CFC-12 and to reduce aerosol propellant uses of these CFCs by at
least 30 percent of 1976 levels by the end of 1981. Several
member countries have achieved significantly greater reductions
in aerosol uses than the required 30 percent. Japan has decided
to cap production capacity informally with end results equivalent
to those of the EEC. Canada, Sweden, and Norway have banned most
aerosol propellant uses of CFC-11 and CFC-12, and many otner
countries have achieved significant reductions without
regulation.
A number of international organizations are active in the
CFC issue. The Organization for Economic Cooperation and
Development (OECD) through its Environment Committee is reviewing
the CFC issue and preparing a report on the current status of the
atmospheric science, potential UV effects, industry facts and
figures, and actions by members and international
organizations. In a related exercise, scientists in several
countries are using an agreed upon set of CFC emission scenarios
in atmospheric modeling studies. The results of this scenario
work will be particularly useful for evaluating the effects on
eventual ozone depletion of alternative emission control
strategies. In the U.S., modelers at Du Pont and Lawrence
Livermore National Laboratory are participating in this effort,
which is being coordinated by EPA. The results are intended for
use by OECD and national policy makers.
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The United Nations Environment Program (UNEP) serves as the
coordinator and evaluator of international research on the
scientific issues. UNEP, through its Coordinating Committee on
the Ozone Layer (CCOL), conducts an annual scientific assessment
of the ozone depletion issue. CCOL has agreed with the World
Meteorological Organization (WMO) suggestion that satellite
measurements be integrated with ground-based observations to
improve ozone monitoring. The group also expressed concern at
increases in nonaerosol uses of CFCs and production of other
potential ozone depleters. In May 1981, the UNEP Governing
Council agreed to a Swedish proposal to begin work on a global
convention to protect stratospheric ozone. The first meeting of
the legal/technical group working on the convention was held in
Stockholm, Sweden in January 1982.
Other groups active internationally include the world Health
Organization, which is participating in an epidemiological study
of skin cancer and other potential UV-related health effects; the
International Committee of Scientific Unions, which is concerned
with biological effects of UV radiation and the overall
scientific issues; and the WMO, which is involved in the
atmospheric science. The Chemical Manufacturers Association,
through its Fluorocarbon Program Panel (an international group),
continues to sponsor experimental research related to improving
the understanding of atmospheric processes, and annually
publishes world production and emissions information for CFC-11
and CFC-12.
Resolution of the domestic control issues will consider the
potential for cooperative action with other nations. It is
anticipated that continuing cooperation to examine various
scientific and policy issues in international fora will lead to
better understanding and development of international responses
to the problem.
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V. FURTHER REGULATION OF CFCS
EPA will conduct a thorough review (including the upcoming
NAS assessment) of the available scientific evidence before
making policy decisions about further control of CFCs. The
current calculated rate of stratospheric depletion of ozone and
moderation of growth in CFC uses in the U.S. and the world may
allow for scientific research and monitoring activities to
continue in order to decrease uncertainties and increase
knowledge while not incurring potentially large impacts on
stratosphere ozone. Any further Agency action will be based on
credible scientific evidence and sound economic analyses subject
to rigorous peer review.
EPA is working closely with other agencies to coordinate the
exchange of research and information and to review potential
responses to the issue by EPA and the other agencies. Agencies
involved in this effort include FDA, Consumer Product Safety
Commission, Department of Commerce, Small Business
Administration, Department of State, and Department of Energy.
In June 1980, EPA published a proposed rule under Part A of
the CAA that would limit emissions of volatile organic compounds
and five halogenated solvents (CFC-113, methyl chloroform,
methylene chloride, perchloroethylene, and trlchloroethylene)
from new, modified, or reconstructed organic solvent cleaners.
EPA is studying whether these halogenated compounds should be
included in a final rule.
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REFERENCES
1. "International Workshop on the Stratosphere, 1981," May 18-
22, 1981, Hampton, Virginia. Draft Report in preparation.
2. Environmental Protection Agency, Materials Balance for Methyl
Chloroform, Level II, Washington, D.C.: OTS, January 1980.
3. D.J. Wuebbles, "The Relative Efficiency of a Number of
Halocarbons for Destroying Stratospheric Ozone," Livermore,
CA: Lawrence Livermore' National Laboratory (DOE Contract No.
W-7405-Eng-48), January 1981.
4. Environmental Protection Agency, "Standards of Performance
for New Stationary Sources; Organic Solvent Cleaners,"
45 FR 39766, June 11, 1980.
5. National Aeronautics and Space Administration, "Present State
of Knowledge of the Upper Atmosphere: An Assessment Report,"
January 1980.
6. National Academy of Sciences, Protection Against Depletion of
Stratospheric Ozone by Chlorofluorocarbons, Washington, D.C.:
NAS, 1979.
7. W. Riggan, J. Van Bruggen, J. Acquavella, and J. Beaubier,
U.S. Cancer Mortality Rates and Trends, 1950-1978, Vol II.,
EPA publication in preparation.
8. Environmental Protection Agency, "Fully Halogenated Chloro-
fluoroalkanes," 43 FR 11318, March 17, 1978 and Food and Drug
Administration, "Certain Fluorocarbons (Chlorofluorocarbons)
in Food, Food Additive, Drug, Animal Foodr. Animal Drug,
Cosmetic, and Medical Device Products as Propellants in Self-
Pressurized Containers," 43 FR 11301, March 17, 1978.
9. Environmental Protection Agency, "Essential Use
Determinations—Revised Support Document to Final Regulation
on Fully Halogenated Chlorofluoroalkanes," March 17, 1978.
10. Environmental Protection Agency, "Fully Halogenated Cnloro-
fluoroalkanes," 46 FR 5981, January 21, 1981.
11. Environmental Protection Agency, "Fully Halogenated Chloro-
fluoroalkanes," 46 FR 27120, May 18, 1981.
12. Environmental Protection Agency, "Fully Halogenated Chloro-
fluoroalkanes," 47 FR 148, January 5, 1982.
13. Environmental Protection Agency, "Fully Halogenated Chloro-
fluoroalkanes," 46 FR 6062, January 21, 1981.
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