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Chlorinated solvents factsIntroductionThis section of the website gives some perspectives on chlorinated solvents, some of industry's most widely used and valued chemicals. Perchloroethylene, trichloroethylene and methylene chloride can be used safely in terms of human health, safety and the environment if following standard guidelines. The only chlorinated solvent which is associated with ozone depletion - 1,1,1-trichloroethane - is regulated by the Montreal Protocol. Its production declined rapidly in the early 1990s and ceased in 1995. The other three solvents do not deplete the ozone layer and their contribution to global warming, acid rain and smog formation is negligible. When used with due care, they pose no threat to the environment, nor to human health or safety. Efficient, non-flammable, and highly recyclable, they often perform at least as well as alternatives which have been proposed, which themselves may have significant impacts on the environment and on human health. The facts presented here have all been substantiated by years of experience of manufacture and use of chlorinated solvents, together with rigorous scientific testing and review of scientific literature. Sensible use of chlorinated solventsChlorinated solvents are used extensively by industry world-wide
World-wide use of chlorinated solvents in 2002 (last update) was approximately 764,000 tonnes, of which some 254,000 tonnes was used in Europe. The quantity used is declining significantly, largely due to reduced emissions to the atmosphere and increased recycling. The quantities will further decrease with the entry into force of the Solvents Emission Directive, also called VOC Directive (since 2001 new installations have had to comply with this with all installations having to comply as of 2007). Technically and environmentally, chlorinated solvents are often the best choiceFor many applications, chlorinated solvents offer the best technical solution. Vapour degreasing, for example, is recognised as the most effective way of cleaning metal components: it would be all but impossible without chlorinated solvents. Other examples include the manufacture of medical equipment, pharmaceuticals, car braking systems, high-specification plastics, aircraft wings and hydraulics, and in crack testing and dry cleaning. There may be alternatives, but they do not necessarily offer a better environmental performance. Water-based cleaning, for instance, may result in contamination of the aqueous environment. Used responsibly, chlorinated solvents have minimal effect on the environment and on healthTrichloroethylene, perchloroethylene and methylene chloride have been widely used for many years, and methods of use have been developed which mean their impact on the environment and on health can be kept to the very minimum. Alternative cleaning methods can also have an impact on the environment, safety and healthAlternatives to cleaning with chlorinated solvents include use of aqueous formulations, hydrocarbon solvents and semi-aqueous systems. None is free of problems. Aqueous systems tend to use more energy than those employing chlorinated solvents. They produce large quantities of contaminated water which must be processed. Hydrocarbon solvents can pose flammability problems and some are harmful to health. The effects on health of some alternatives have yet to be fully evaluated. ECSA members are committed to helping their customers use and dispose of chlorinated solvents responsiblySolvent manufacturers who are members of ECSA, and their distributors, have made a commitment to assist their customers to use chlorinated solvents safely and responsibly. This commitment extends to providing literature and training on handling, storage, use and recycling of solvents, and final disposal of spent solvent and wastes which arise from its use. European trade associations share the commitment to responsible use of chlorinated solventsOver the years ECSA has signed voluntary agreements with several trade associations representing distributors, metal cleaners and dry cleaners. These commit the associations' members to continuing improvements in the reduction of solvent emissions, as well as responsible use and disposal or residues. Chlorinated solvents are readily recycledOnce they have been used for surface cleaning and other processes, chlorinated solvents can be readily and safely distilled. The recovered material can be used again, and the process repeated many times over. This makes a major contribution to the economy of processes which use chlorinated solvents. Recycling saves resources and reduces the amount of waste requiring disposal. Solvent manufacturers and distributors have systems in place to ensure chlorinated solvent waste is correctly managedThroughout Europe, many manufacturers and distributors offer to collect spent solvent when making deliveries of fresh material to customers. These systems ensure that waste is disposed of in full compliance with national and international regulations. Chlorinated solvents and healthImpact on healthThere is no evidence that exposure to normal levels of perchloroethylene, methylene chloride and 1,1,1-trichloroethane increases the risk of cancer in humans: although exposure of certain rodents exposed to some chlorinated solvents, often at very high levels, can cause tumours, extensive toxicological and epidemiological research has not conclusively determined any correlation to humans. It is strongly recommended that users stay within legislative or manufacturers' guidelines on workplace exposure. Inhalation of solvent vapour is the most frequent route of exposure: solvent vapours are heavier than air and can accumulate in confined or poorly ventilated areas. Over-exposure, as with many other substances, can lead to unconsciousness and even death. Correct ventilation is vital. Individuals exposed in their work perchloroethylene, methylene chloride and 1,1,1-trichloroethane have been studied over many years. The weight of evidence is that, at normal levels, these solvents are not carcinogenic to humans. Some animal studies have suggested that certain chlorinated solvents cause cancer in rats or in mice at exceptionally high exposure levels bearing no relevance to occupational exposure. The ways these tumours occur have been identified and the mechanisms have been found to be specific to rodents and not relevant to humans. Trichloroethylene has been classified as Carc. Cat. 2, but not as Carc. Cat. 1. Therefore trichloroethylene is not proven to be carcinogenic in humans.
When properly handled, chlorinated solvents pose no danger to humansChlorinated solvents have been used extensively for many years. During this time, the only fatalities or serious injuries which have occurred have been due to massive over-exposure through a total disregard for good operating practices, or through deliberate misuse. When solvents are stored, used and disposed of correctly, there is no risk to human health. Manufacture of chlorinated solvents does not harm health or the environmentDuring the production of chlorinated solvents, integrated manufacturing methods are employed so that waste from one process is used in another process. As a result, waste from the manufacturing plant is kept to a minimum, and toxic and environmentally damaging wastes are recycled and converted to useful products, and final waste is properly disposed of. Chlorinated solvents and the environmentEnvironmental impactChlorinated solvents have an insignificant effect on the atmosphere: with total solvent emissions to the atmosphere in Western Europe from all sources estimated at some 4-4.5 million tonnes per year, chlorinated solvents represent less than 8% of the total. They degrade within 6-8 days (trichloroethylene) and 5-6 months (perchloroethylene and methylene chloride) and are regarded as low tropospheric ozone creators as well as insignificant (<0.5%) contributors to acid rain formation. The ODP (stratospheric Ozone Depletion Potential) is negligible and they are not regulated by the Montreal Protocol. Chlorinated solvents are unlikely to accumulate in the environment. As discussed above, chlorinated solvents have a relatively short atmospheric lifetime. Spillages to water or soil are most likely to re-evaporate to the atmosphere, where they will break down. Furthermore, methylene chloride is completely biodegradable under both aerobic and anaerobic conditions. Perchloroethylene and trichloroethylene display much slower biodegradation especially under anaerobic conditions, and for this reason, ECSA encourages spillage containment systems in storage and use areas. Furthermore, ECSA strongly discourages land filling of waste, even though this may be legal in some areas. None of the three solvents is regarded as bio-accumulative (log Pow <3; bio-concentration factor <100: these are the terms that define respectively rate of breakdown of the molecule, and tendency to accumulate in marine organisms). Production of the only chlorinated solvent associated with ozone depletion ceased in 1995Due to concerns that 1,1,1-trichloroethane contributed to ozone depletion, it was phased out completely in 1995. This has resulted in the decline of chlorine loading of the stratosphere, despite continuing emissions of CFCs in developing countries. Chlorinated solvents which have no effect on the ozone layer are availableThe mixing time for a gas between its emission at ground level and transport into the stratosphere is in the range of 1-2 years. Because of their relatively short life-time in the atmosphere, trichloroethylene, perchloroethylene and methylene chloride are almost totally broken down before reaching the stratospheric ozone layer. Therefore, their effect is minimal and their ODP (Ozone Depletion Potential) is considered as negligible.
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The contribution of chlorinated solvents to global warming is negligibleThe three major chlorinated solvents are quickly broken down in the atmosphere, and are emitted in very low concentrations. As a result their contribution to global warming is very low.
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Chlorinated solvents make a negligible contribution to acid rain productionMan's major contribution to acid rain is the burning of fossil fuels, which release oxides of sulphur and nitrogen. The quantities of chlorinated solvents released into the atmosphere are insignificant compared with the amounts of these oxides produced. Chlorinated solvents are estimated to contribute to much less than 1% of the acid rain produced through human activities. Reference:
Chlorinated solvents are unlikely to accumulate in the environmentChlorinated solvents have a relatively short life-time in the atmosphere. If spilt into water or soil, trichloroethylene, perchloroethylene and methylene chloride will usually evaporate into the air, where they are quickly broken down. Methylene chloride is completely biodegradable under both aerobic and anaerobic conditions. Perchloroethylene and trichloroethylene display very slow biodegradation and ECSA encourages endusers to be very careful to avoid spillages. Today's groundwater pollution is clearly the result of past spillages and inappropriate waste disposal. The contribution of chlorinated solvents to smog formation is less than 0.5%Many organic chemicals in widespread daily use, such as petrol and alcohol solvents, contribute to the formation of smog by creating ozone in the lower atmosphere. Chlorinated solvents make a negligible contribution to this effect. It is estimated that these solvents caused less than half of one per cent of smog formation in Western Europe, since when their emissions have been significantly reduced. Photochemical smogThe breakdown of volatile organic compounds in the lower atmosphere yields tropospheric ozone which promotes photochemical smog. Ozone Creation Potential is a measure of the contribution to this effect.
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ECSA hopes that this information has been helpful to you. If you have further questions or would like more information, please contact any of the ECSA member companies or ECSA directly at: European Chlorinated Solvent Association (ECSA) Avenue E. Van Nieuwenhuyse, 4 Printed copies are available on request. Revised April 2007 |
