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Testing Alternatives to CFCs
To test alternatives to CFCs for their environmental, health, and safety characteristics, 17 of the world's chemical companies joined together to form the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS) and the Programme for Alternative Fluorocarbon Toxicity Testing (PAFT). These two programs were set up to provide research on the potential effects of CFC alternatives on the environment and on human health - through international cooperation with independent scientists, with government research programs, and among the companies. AFEAS and PAFT were established by the same companies that sponsored the Fluorocarbon Program, a 17-year research program on the environmental fate and effects of CFCs conducted in the 1970s and 1980s.For many years, CFCs have performed vital roles in society. They are used in a variety of applications including refrigeration, air conditioning, energy-efficient insulation, medical products, and cleaning of critical electronic and precision engineering components. It was important for users of these chemicals to have effective alternatives as soon as possible. Further, it was essential that decisions on the health and environmental safety of these alternatives were based on the best available scientific information.
By combining their resources and cooperating with academic and government research programs, the AFEAS and PAFT companies substantially reduced the usual period of time for environmental and toxicity testing of new chemicals. This effort is assisting with the rapid phaseout of CFCs.
AFEAS
The initial phase of AFEAS began in 1988 with a complete review by leading scientists of data pertinent to the environmental acceptability of alternative fluorocarbons. The review was published as a separate volume of the UNEP/WMO Scientific Assessment of Stratospheric Ozone: 1989. The results indicated that all of the proposed alternatives were significantly more environmentally acceptable than CFCs. The alternatives have small or zero ozone depletion potentials and make a minimal contribution to global warming. In 1990, AFEAS was expanded into a three-year research and assessment program to identify and help resolve gaps in knowledge regarding the potential environmental effects of alternative fluorocarbons. The program was extended by another three years in 1993 and again in 1996 to focus on key remaining issues. Funding for the 11 years of AFEAS totals more than 11 million U.S. dollars.The proposed alternatives are hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). The presence of hydrogen in their structure means that, unlike CFCs, the compounds are largely removed in the lower atmosphere by natural processes. Based on assessments of expert scientists who contributed to the first AFEAS report, it is expected that the atmospheric breakdown products will not have serious environmental impacts. Subsequent research has verified the original assessment. Work is underway to investigate the potential environmental impacts of the one breakdown product for which there is no known natural source.
Because they are destroyed more rapidly in the lower atmosphere by natural processes than CFCs, the alternative compounds will not accumulate in the atmosphere to the same extent. This means that they have a smaller potential to contribute to the greenhouse effect. Furthermore they promote efficient use of energy. This is important when the direct contribution to global warming from emissions of the alternative fluorocarbons is compared with the indirect contribution of carbon dioxide emissions resulting from the energy required to operate the refrigeration or air-conditioning system over its normal lifetime.
An important component of the AFEAS program is the Global Warming and Energy Efficiency Study, co-funded with the U.S. Department of Energy. The total equivalent warming impact (TEWI) from both direct and indirect contributions to global warming has been quantified for each alternative, including non-chemical alternatives, in the major application areas (i.e., refrigeration, air-conditioning, insulation, and solvents). This analysis has shown that, in a number of cases, the use of HCFCs or HFCs can lead to better energy efficiency and thus to smaller indirect contributions than non-fluorocarbon technologies. The TEWI study was expanded in 1994 to include more non-fluorocarbon technologies and then updated in 1996 with the most recent data available for a large number of alternatives to CFCs.
PAFT
Under PAFT, eight alternative fluorocarbons 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 first of the PAFT program sectors was launched in December 1987 to evaluate the toxicology of 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. The participating companies have contributed on the order of 24 million U.S. dollars for PAFT studies, not to mention the costs for in-house studies which are probably of a similar magnitude.PAFT represents the first time that a worldwide industry has voluntarily undertaken the cooperative testing of the health and safety characteristics of new compounds - conducted in close coordination with regulatory bodies. This cooperation generated a dynamic, comprehensive program that provided valuable, scientifically credible information in the shortest possible time frame. This level of effort shows the total commitment of the PAFT member companies to ensuring the prompt availability of safe alternatives.
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