Programme for
Alternative Fluorocarbon
Toxicity Testing

"All information to date suggests that the proposed substitutes are significantly much better than the current CFCs relative to protection of the ozone layer. The ODPs and GWPs are much smaller than those for the CFCs, and they should not contribute to tropospheric ozone or acid deposition. Consequently, industry is scientifically justified in proceeding rapidly towards the commercialization of these chemicals."

R.T. Watson, M.J. Prather and D.L. Albritton
UNEP/Ozl.Pro.WG.II(1)/CRP.1 13 Nov 1989

In response to increasing concerns that certain chlorine-containing compounds, such as the fully halogenated chlorofluorocarbons (CFCs), may be catalysing a decrease in stratospheric ozone levels, the world's major producers of these chemicals agreed to work together to evaluate the toxicity of potential replacements. The Programme for Alternative Fluorocarbon Toxicity Testing (PAFT) is a cooperative research effort sponsored by 16 of the leading CFC producers. The programme was designed to expedite the development of toxicology data for possible substitute fluorocarbons.

Fluorocarbon Alternatives
Tested under PAFT

HFC-32 CH2F2

HFC-125 CHF2CF3

HFC-134a CH2FCF3

HCFC-123 CHCl2CF3

HCFC-124 CHClFCF3

HCFC-141b CH3CCl2F

HCFC-225ca CHCl2CF2CF3

HCFC-225cb CHClFCF2CClF2

The first of several PAFT programme sectors was launched in December 1987 to evaluate the toxicology of two compounds: HFC-134a and HCFC-123. Additional sectors followed covering HCFC-141b, HCFC-124, HFC-125, HCFC-225ca/cb, and HFC-32. All of these studies have now been completed. The only remaining ongoing effort under PAFT involves general studies of mechanistic, metabolic and pharmacokinetic aspects of the toxicology of fluorocarbons, which are not compound specific.

Fluorocarbon Alternatives Tested under PAFT
HFC-32	CH2F2
HFC-125	CHF2CF3
HFC-134a	CH2FCF3
HCFC-123	CHCl2CF3
HCFC-124	CHClFCF3
HCFC-141b	CH3CCl2F
HCFC-225ca	CHCl2CF2CF3
HCFC-225cb	CHClFCF2CClF2

The eight compounds listed to the right have been exhaustively tested through more than 200 individual studies and the involvement of a dozen testing laboratories in Europe, Japan and North America. The companies sponsoring PAFT have contributed on the order of 21 million U.S. dollars for PAFT studies, not to mention the costs for in-house studies which are probably of a similar magnitude.

The information from the various PAFT sectors has been reported to regulatory bodies as it has become available. The results have also been presented at numerous scientific conferences worldwide. In addition, PAFT results have formed the basis for a series of assessment reports published by the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC), and have been used in the UNEP assessments required under the Montreal Protocol. PAFT intends to publish all studies in peer-reviewed scientific journals.

A summary document has been prepared that describes the history, background and operation of PAFT, as well as the results of the toxicity studies. An overview of the five PAFT programme sectors follows.

PAFT-I
CFC-12 --> HFC-134a
CFC-11 --> HCFC-123

refrigeration
air-conditioning
certain foams
medical aerosols

fire-fighting
certain cleaning uses
air-conditioning

Testing of HCFC-123 and HFC-134a under PAFT I was initiated in 1987 and concluded in 1993. Results indicate that HFC-134a has very low toxicity. An exposure limit of 1,000 ppm (8-hour time-weighted average) has been recommended by the American Industrial Hygiene Association, Workplace Environmental Exposure Limit (WEEL) Committee. Studies of HCFC-123 show this compound to have low toxicity. Several PAFT companies have set occupational exposure limits for HCFC-123 typically at 10 or 30 ppm (8-hour time-weighted average).


CFC-12 HFC-134a	CFC-11 HCFC-123
refrigeration air-conditioning certain foams medical aerosols	fire-fighting certain cleaning uses air-conditioning
	Testing of HCFC-123 and HFC-134a under PAFT I was initiated in 1987 and concluded in 1993. Results indicate that HFC-134a has very low toxicity. An exposure limit of 1,000 ppm (8-hour time-weighted average) has been recommended by the American Industrial Hygiene Association, Workplace Environmental Exposure Limit (WEEL) Committee. Studies of HCFC-123 show this compound to have low toxicity. Several PAFT companies have set occupational exposure limits for HCFC-123 typically at 10 or 30 ppm (8-hour time-weighted average).

PAFT-II
CFC-11 --> HCFC-141b

energy-efficient insulating foams
solvent cleaning

The testing of HCFC-141b under PAFT II was completed in 1993. Results show that HCFC-141b has low toxicity, allowing the use in appropriate applications under controlled conditions of occupational exposure. An exposure limit of 500 ppm (8-hour time-weighted average) has been recommended by the WEEL Committee.

PAFT-III
CFC-114 --> HCFC-124
CFC-115 --> HCFC-125

certain refrigeration uses

The PAFT III programme began in late 1989 and was completed in 1995. Results show that both HCFC-124 and HFC-125 have low toxicity. An exposure limit of 1,000 ppm (8-hour time-weighted average) has been recommended for both compounds by the WEEL Committee.

PAFT-IV
CFC-113 --> HCFC-225 ca/cb

solvent cleaning

The PAFT IV programme was initiated in 1992 and completed in 1994. Tests were conducted on HCFC-225ca and HCFC-225cb as separate isomers and as a 45/55 weight percent mixture. The results indicate that HCFC-225ca and HCFC-225cb have relatively low toxicity, allowing the use of appropriate mixtures in appropriate applications under controlled conditions of occupational exposure.

PAFT-V
CFC-115/R-502 --> HFC-32
HCFC-22 --> HFC-32

certain refrigeration uses

The testing of HFC-32 under the PAFT V programme began in early 1992 and concluded in 1994. The results show a very low order of toxicity. An exposure limit of 1,000 ppm (8-hour time-weighted average) has been recommended by the WEEL Committee.

The Programme for Alternative Fluorocarbon Toxicity Testing (PAFT) is a far-reaching, balanced toxicology evaluation, which has thoroughly tested eight possible alternative fluorocarbons -- both hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs). The programme integrates past and present toxicological information to perform a careful risk assessment including elements of acute, sub-chronic, developmental and chronic toxicity / carcinogenicity studies, studies, genotoxicity studies, and environmental toxicology studies. The compound-specific studies are now complete.

The goal of the programme was to derive the maximum amount of information in a minimum amount of time. The programme sponsors worked through problems with shortages of material for toxicology testing, which required production to begin even prior to market evaluation and at a stage when the economic future for the chemicals was still uncertain. The needs of regulatory authorities in Europe, the Far East and the United States also had to be taken into account. To achieve these goals, the programme pooled the expertise of toxicologists worldwide with collective experience representing more than 100 years of research into fluorocarbon toxicity.

PAFT was recognized by the regulatory authorities of the European Community, Japan, and the United States in a joint communiqué issued in October 1991. The distinguished bodies supported the test programmes being undertaken by PAFT and endorsed the appropriateness of the studies.

Through the development of a broad base of support -- 16 companies from 9 countries -- PAFT has been able to evaluate a number of possible chemicals in a comprehensive, cost-effective, and timely manner providing industry and the public with safe, viable alternatives to the chlorofluorocarbons.

September 1995

For further information contact:

PAFT Program Office 1200 South Hayes Street Arlington, VA 22202-5050 USA

Last updated June 20, 2000

	"All information to date suggests that the proposed substitutes are significantly much better than the current CFCs relative to protection of the ozone layer. The ODPs and GWPs are much smaller than those for the CFCs, and they should not contribute to tropospheric ozone or acid deposition. Consequently, industry is scientifically justified in proceeding rapidly towards the commercialization of these chemicals."
	R.T. Watson, M.J. Prather and D.L. Albritton UNEP/Ozl.Pro.WG.II(1)/CRP.1 13 Nov 1989

	CFC-11 HCFC-141b

	energy-efficient insulating foams solvent cleaning
		The testing of HCFC-141b under PAFT II was completed in 1993. Results show that HCFC-141b has low toxicity, allowing the use in appropriate applications under controlled conditions of occupational exposure. An exposure limit of 500 ppm (8-hour time-weighted average) has been recommended by the WEEL Committee.

	CFC-114 HCFC-124 CFC-115 HCFC-125		certain refrigeration uses

		The PAFT III programme began in late 1989 and was completed in 1995. Results show that both HCFC-124 and HFC-125 have low toxicity. An exposure limit of 1,000 ppm (8-hour time-weighted average) has been recommended for both compounds by the WEEL Committee.

	CFC-113 HCFC-225 ca/cb		solvent cleaning

		The PAFT IV programme was initiated in 1992 and completed in 1994. Tests were conducted on HCFC-225ca and HCFC-225cb as separate isomers and as a 45/55 weight percent mixture. The results indicate that HCFC-225ca and HCFC-225cb have relatively low toxicity, allowing the use of appropriate mixtures in appropriate applications under controlled conditions of occupational exposure.

	CFC-115/R-502 HFC-32 HCFC-22 HFC-32		certain refrigeration uses

		The testing of HFC-32 under the PAFT V programme began in early 1992 and concluded in 1994. The results show a very low order of toxicity. An exposure limit of 1,000 ppm (8-hour time-weighted average) has been recommended by the WEEL Committee.