Ozone-Depleting Substances: Alternatives

Home , Carbon tetrachloride, Hydrofluorocarbon

Pollution Prevention and Abatement Handbook WORLD BANK GROUP Effective July 1998

Surrounding the earth at a height of about 25 international environmental agreement, and its kilometers is the stratosphere, rich in ozone, signing by so many nations represented a major which prevents the sun’s harmful ultraviolet accomplishment, and a major shift in the ap- (UV-B) rays from reaching the earth. UV-B rays proach to handling global environmental prob- have an adverse effect on all living organisms, lems. The Protocol called for a freeze on the including marine life, crops, animals and birds, production of halons and a requirement to reduce and humans. In humans, UV-B is known to af- the production of CFCs by 50% by 1999. How- fect the immune system; to cause skin cancer, eye ever, new scientific evidence surfaced after the damage, and cataracts; and to increase suscepti- entry into force of the Protocol, indicating that bility to infectious diseases such as malaria. ozone depletion was more serious than originally In 1974, it was hypothesized that chlorinated thought. Accordingly, in 1990 (London), 1992 compounds were able to persist in the atmo- (Copenhagen), and 1995 (Vienna), amendments sphere long enough to reach the stratosphere, were made to the Protocol to regulate the phase- where solar radiation would break up the mol- out of the original chemicals and the control and ecules and release chlorine atoms that would phase-out of additional chemicals. destroy the ozone. Mounting evidence and the discovery of the Antarctic ozone hole in 1985 led to the global program to control chlorofluorocar- Table 1. Ozone Depletion Potential (ODP) of the bons (CFCs) and other ozone-destroying chemi- Principal Ozone-Depleting Substances (ODSs) cals. In addition to Antarctica, ozone loss is now ODS ODP present over New Zealand, Australia, southern Argentina and Chile, North America, Europe, CFC-11 1.0 and Russia. CFC-12 1.0 The ozone-depleting chemicals or substances CFC-113 0.8 CFC-114 1.0 (ODSs) of concern are CFCs, halons, methyl chlo- CFC-115 0.6 roform (1,1,1,-trichloroethane; MCF), carbon tet- CFC-111, -112, -13, -211, -212, rachloride (CTC), hydrochlorofluorocarbons -213, -214, -215, -216, -217 1.0 (HCFCs), and methyl bromide. The ozone deple- Halon 1211 3.0 tion potential (ODP) for these chemicals is shown Halon 1301 10.0 in Table 1. CFC-11 was assigned an ODP of 1.0; Halon 2402 6.0 all other chemicals have an ODP relative to that Carbon tetrachloride (CTC) 1.1 Methyl chloroform (MCF); of CFC-11. An ODP higher than 1.0 means that 1,1,1-trichloroethane 0.1 the chemical has a greater ability than CFC-11 to HCFC-22 0.05 destroy the ozone layer; an ODP lower than 1.0 HCFC-123 0.02 means that the chemical’s ability to destroy the HCFC-124 0.02 ozone layer is less than that of CFC-11. HCFC-141b 0.15 In September 1987, the Montreal Protocol on HCFC-142b 0.06 Substances That Deplete the Ozone Layer (the HCFC-225ca 0.01 HCFC-225cb 0.04 Protocol) was signed by 25 nations and the Eu- Methyl bromide 0.7 ropean Community. The Protocol was the first

250 Ozone-Depleting Substances: Alternatives 251

The principal provisions of the Montreal Pro- preinvestment studies, training and work- tocol as it now stands are as follows: shops, demonstration projects, investment project design, and country programs. • Production of CFCs, halons, methyl chloro- • The United Nations Industrial Development Or- form, and CTC ceased at the end of 1995 in ganization (UNIDO) implements small and me- industrial countries and will cease by 2010 in dium-scale projects, feasibility studies at the developing countries. Developing countries plant level, technical assistance and training, are defined in the Protocol as those that use and country programs. less than 0.3 kilograms (kg) of ODS per capita per year. They are often called Article 5 coun- Uses of ODSs tries in reference to the defining article in the Montreal Protocol. In general, ODSs are most often used in the fol- • HCFCs, originally developed as a less harm- lowing applications: ful class of CFC alternatives, will be phased out by 2020 in industrial countries, with some • As propellants in aerosols (CFCs and HCFCs) provisions for servicing equipment to 2030. • In refrigeration, air conditioning, chillers, and Developing countries are to freeze consump- other cooling equipment (CFCs and HCFCs) tion by 2016 (base year 2015) and phase out • To extinguish fires (halons) use by 2040. • In the manufacture of foams (CFCs and • Consumption and production of methyl bro- HCFCs) mide will end in 2005 in industrial countries • As solvents for cleaning printed circuit boards (subject to phase-out stages and exemptions) and precision parts and degreasing metal parts and in 2015 in developing countries. (CFCs, HCFCs, methyl chloroform, and CTC) • In a variety of other areas, such as inks and It was early recognized that undue hardships coatings and medical applications (CFCs, might be experienced by industry in developing HCFCs, methyl chloroform, and CTC) countries as they implemented replacement tech- • As a fumigant (methyl bromide). nologies. Therefore, a fund was established under the Montreal Protocol to pay for incremental Alternative Technologies, Processes, costs such as technical expertise and new technolo- and Chemicals gies, processes, and equipment associated with the phase-out. The Multilateral Fund of the Montreal Protocol is managed by an executive committee The following discussion provides a brief over- consisting of delegates from seven developing view of the alternatives to ODSs that have been countries and seven industrial countries. The fol- developed in various sectors. It is not intended lowing international organizations have been to be an exhaustive listing of all alternatives, but made Implementing Agencies of the Multilateral it does summarize some proven alternatives and Fund for the purpose of helping governments give an indication of future development trends. and industries in developing countries with their The selection of any alternative should be made programs to eliminate ODSs. (The roles outlined with due consideration of other issues that could here are not intended to be exhaustive.) affect the final choice. Identification, development, and commercial- • The World Bank assists developing coun- ization of alternatives to ODSs are going on con- tries with investment projects, country stantly. For this reason it is important to seek programs, workshops, training, and institu- information on the latest alternatives from the tional strengthening. World Bank’s Global Environment Coordination • The United Nations Environment Programme Division. Technological updates are provided by (UNEP) has a clearinghouse function that in- the World Bank’s Ozone Operations Resource cludes information exchange, country pro- Group, which is made up of experts in halons, grams, training, and workshops. solvents, aerosols, refrigerants, mobile air con- • The United Nations Development Programme ditioning, foam blowing, and chemical produc- (UNDP) is responsible for feasibility and tion. For any alternative, consideration needs to 252 PROJECT GUIDELINES: POLLUTANT CONTROL TECHNOLOGIES be given to, for example, its compatibility with Rigid polyurethane for other appliances. Alterna- existing equipment, its health and safety aspects, tives include HCFC-141b, HCFC-22, blends of its direct global-warming potential, whether it in- -22 and HCFC-142b, pentane, and carbon diox- creases or decreases energy consumption, and the ide/water blowing. In the long term, the alter- costs that may be incurred in eventual conversion natives include HFCs. to a non-ODS technology if an interim HCFC alternative is chosen. New ways of doing business Rigid polyurethane used for boardstock and flex- may also develop in the course of review and se- ible-faced laminations. Alternatives include HCFC- lection of alternatives. For example, many elec- 141b and pentane; in the long term, the use of tronics companies have now converted their HFCs should be developed. manufacturing plants to “no-clean” technology. The benefits include elimination of circuit board Sandwich panels of rigid polyurethane. HCFC- cleaning after soldering, savings in chemical costs 141b, HCFC-22, blends of HCFC-22 and -141b, and waste disposal costs, savings in maintenance pentane, and HFC-134a are now used as alterna- and energy consumption, improved product qual- tives to CFCs in this application. In the long term, ity, and advances toward new technologies such HFCs and carbon dioxide/water will be the re- as fluxless soldering. The selection of any alterna- placement technologies. tive should not be made in isolation from the fac- tors listed above. Spray applications of rigid polyurethane. Alterna- tives currently in use for spray applications in- Flexible and Rigid Foams clude carbon dioxide/water and HCFC-141b. Long-term alternatives will be HFCs. Zero-ODP alternatives are the substitutes of choice in many foam-manufacturing applica- Slabstock of rigid polyurethane. Alternatives in- tions. However, the use of HCFCs is sometimes clude HCFC-141b; long-term alternatives include necessary in order to meet some product specifi- HFCs and carbon dioxide/water. Pentane may cations. The viability of liquid hydrofluorocarbon also be used. (HFC) isomers in this industry remains to be proved, and hydrocarbon alternatives need to be Rigid polyurethane pipe construction. CFCs in this better qualified, as well. The issues in these evalu- application are being replaced by carbon dioxide/ ations are safety (toxicity and flammability), en- water, HCFC-22, blends of HCFC-22 and -142b, vironmental impact (generation of volatile HCFC-141b, and pentanes. Long-term alternatives organic compounds and global warming), prod- will include HFCs and carbon dioxide/water. For uct performance (insulating properties, confor- district central heating pipes, pentane and carbon mity to fire codes, and the like), cost and dioxide/water are the preferred technologies. availability, and regulatory requirements. The next sections summarize the alternatives Polyurethane flexible slab. Many alternatives for specific products of the foam manufacturing now exist for flexible slab construction, includ- sector. Because of the complexity of the industry ing extended range polyols, carbon dioxide/ and the variety of products, the alternatives have water, softening agents, methylene chloride, been listed briefly as short-term and long-term acetone, increased density, HCFC-141b, pentane, options, without an elaboration of the merits of and other alternative technologies such as accel- each. Additional information is available in the erated cooling and variable pressure. The long 1995 UNEP Technical Options Report for this term will probably see the use of injected carbon sector. dioxide and alternative technologies.

Rigid polyurethane foams used in refrigerators and Molded flexible polyurethane. The standard now freezers. Alternatives include hydrocarbons (pen- is carbon dioxide/water blowing. tane) and HCFC-141b; long-term alternatives include HFCs (-134a, -245, -356, -365). Vacuum Integral-skin polyurethane products. The current panels may be used in the future. alternatives for these products include HCFC-22, Ozone-Depleting Substances: Alternatives 253 hydrocarbons, carbon dioxide/water, HFC-134a, factory. Neither HC-600a nor HFC-134a is con- pentanes, and HCFC-141b. The long-term alter- sidered an alternative for retrofitting domestic nate is expected to be carbon dioxide/water. refrigeration appliances, but preliminary data indicate that a combination of the two may be a Phenolic foams. Phenolic foams can now be retrofit, or “servicing,” candidate. made using HCFC-141b, hydrocarbons, injected carbon dioxide, or HFC-152a instead of CFCs. In Commercial refrigeration. Alternatives to CFCs for the long term, HFCs may be the predominant new commercial refrigeration equipment include alternative. HCFCs (including HCFC mixtures) and HFCs and HFC mixtures. Retrofit of existing equipment is Extruded polystyrene sheet. Alternatives cur- possible by using both HCFCs and HFCs, in con- rently include HCFC-22, hydrocarbons, injected junction with reduced charges and more efficient carbon dioxide, and HFC-152a. In the long term, compressors. Hydrocarbons are, to a small extent, these same alternatives (except for HCFC-22) will applied in hermetically sealed systems. be used, along with possible use of atmospheric gases. Cold storage and food processing. Although there has been a return to the use of ammonia for some Extruded polystyrene boardstock. HCFC-22 and cold storage facilities, there are safety issues, and -142b and injected carbon dioxide are the current some regulatory jurisdictions restrict its use. Other alternatives. Long-term alternatives will be HFCs alternatives to CFCs in cold storage and large and injected carbon dioxide. commercial food preservation facilities include HCFC-22 and HFC blends. Hydrocarbons and Polyolefins. Polyolefins are now manufactured HCFC-22 will continue to be the favored alter- using alternatives such as hydrocarbons, HCFC- natives until equipment using other alternatives 22 and -142b, injected carbon dioxide, and HFC- is developed; ammonia will be used in selected 152a. Hydrocarbons and injected carbon dioxide applications. will be long-term alternatives. Industrial refrigeration. New industrial refrigera- Refrigeration, Air Conditioning, and Heat Pumps tion systems that are used by the chemical, petro- chemical, pharmaceutical, oil and gas, and Refrigeration technology has also been rapidly metallurgical industries, as well for industrial ice evolving. Immediate replacements for many ap- making and for sports and leisure facilities, can plications include hydrocarbons, HFCs, and use ammonia and hydrocarbons as the refriger- HCFCs. Some of these will also be candidates for ant. Although the product base concerned is small, long-term replacement of the currently used existing CFC equipment can be retrofitted to use CFCs. This section briefly describes the alterna- HCFC-22, HFCs and HFC blends, and hydro- tives that are available for specific refrigeration, carbons. air conditioning, and heat pump applications. Air conditioning and heat pumps (air-cooled sys- Domestic refrigeration. Two refrigerant alterna- tems). Equipment manufactured in this category tives are predominant for the manufacture of new generally uses HCFC-22 as the refrigerant. Al- domestic refrigerators. HFC-134a has no ozone ternatives under investigation include HFCs depletion potential and is nonflammable, but it and HCs (propane). The most promising of these has a high global-warming potential (GWP). HC- are the nonflammable, nontoxic HFC com- 600a is flammable, has a zero ODP, and has a pounds, although there is more interest in pro- GWP approaching zero. Other alternatives for pane in various regions. HCFs have been some applications include HFC-152a and binary criticized for their global warming potential, but and ternary blends of HCFCs and HFCs. Retro- their total equivalent warming impact (TEWI), fitting alternatives may include HCFC/HFC a measure that combines GWP and energy effi- blends, after CFCs are no longer available. How- ciency. is equal to or lower than that of the other ever, the results obtained so far are still not satis- alternatives. 254 PROJECT GUIDELINES: POLLUTANT CONTROL TECHNOLOGIES

Air conditioning (water chillers). HCFC-22 has Electronics cleaning. Experience has confirmed been used in small chillers, and CFC-11 and -12 that for most uses in the electronics industry, have been used in large chillers that employ cen- ozone-depleting solvents can be replaced easily trifugal compressors. HFC blends are now be- and, often, economically. A wide choice of alter- ginning to be introduced to replace HCFC-22 in natives exists. If technical specifications do not small chillers; HCFC-123 and HFC-134a are the require postsolder cleaning, no-clean is the pre- preferred replacements for large units. Chillers ferred technology. If cleaning is required, the use that have used CFC-114 can be converted to use of water-soluble chemistry has generally proved HCFC-124 or can be replaced by HFC-134a to be reliable. Water-soluble chemistry is not, units. however, suitable for all applications.

Transport refrigeration. HCFC-22 and CFC-502 Precision cleaning. Precision cleaning applica- have been the refrigerants of choice for transport tions are defined as requiring a high level of clean- refrigeration units, although some applications are liness in order to maintain low-clearance or using ammonia as the refrigerant. The alternatives high-reliability components in working order. To include various HFC blends. meet exacting specifications, the alternatives that have been developed include solvent and Automotive air conditioning. The manufacturers nonsolvent applications. Solvent options include of new automobiles have chosen HFC-134a as the alcohols, aliphatic hydrocarbons, HCFCs and their fluid for air conditioning units, and retrofit kits blends, and aqueous and semiaqueous cleaners. are now available to allow older automobiles to Nonsolvent options include supercritical fluid convert to this alternative. cleaning (SCF), ultraviolet (UV)/ozone cleaning, pressurized gases, and plasma cleaning. Heat pumps (heating-only and heat recovery). New heating-only heat pumps use HCFC-22, Metal cleaning. Oils and greases, particulate and this is expected to continue. HFC-134a is matter, and inorganic particles are removed from an alternative for retrofitting existing heat metal parts prior to subsequent processing steps pumps, and investigation into the use of am- such as further machining, electroplating, paint- monia for large-capacity heat pumps is continu- ing. Alternatives to ozone-depleting solvents that ing. Other alternatives being explored include have been developed include solvent blends, propane, other hydrocarbons, and hydrocarbon aqueous cleaners, emulsion cleaners, mechani- blends. cal cleaning, thermal vacuum deoiling, and no- clean alternatives. Solvents, Coatings, Inks, and Adhesives Dry cleaning. Several solvents exist to replace the There now exist alternatives or sufficient quanti- ozone-depleting solvents that have traditionally ties of controlled substances for almost all appli- been used by the dry cleaning industry. Perchlo- cations of ozone-depleting solvents. Exceptions roethylene has been used for over 30 years. Petro- have been noted for certain laboratory and ana- leum solvents, while flammable, can be safely used lytical uses and for manufacture of space shuttle when appropriate safety precautions are taken. rocket motors. HCFCs have not been adopted on They include white spirit, Stoddard solvent, hy- a large scale as alternatives to CFC solvents. In drocarbon solvents, isoparaffins, and n-paraffin. the near term, however, they may be needed as A number of HCFCs can also be used but should transitional substances in some limited and be considered only as transitional alternatives. unique applications. The UNEP Solvents Tech- nical Options Committee does not recommend Adhesives. Methyl chloroform has been used HCFC-141b as a replacement for methyl chloro- extensively by the adhesives manufacturing in- form (1,1,1-trichloroethane) because its ODP is dustry because of its characteristics—it is nonflam- three times higher. Alternatives for specific uses mable and quick drying, and it does not contribute of ozone-depleting solvents are described in this to local air pollution—and its performance. One section. alternative for some applications is water-based Ozone-Depleting Substances: Alternatives 255 adhesives. Other alternatives include hot melt Halons adhesives; radiation-cured adhesives; high-solids adhesives; one-part epoxies, urethanes, and natu- Halon hand-held extinguishers (containing 1211). ral resins in powder form; moisture-cured adhe- These can be replaced, in most applications, by sives; and reactive liquids. multipurpose dry chemical extinguishers.

Coatings and inks. Improvements have been Halon 1301 total flood systems. New and existing made to water-based coatings, and these can be a alternatives are available for most halon 1301 to- substitute for ODS-based applications. Water- tal flood systems. These alternatives include zero- based coatings have been used in the following ODP halocarbons, inert gas mixtures, and new industries and manufacturing sectors: furniture, water-based technologies (e.g., water mist). The automotive electronics, aluminum siding, hard- use of HCFCs and hydrobromofluorocarbons board, metal containers, appliances, structural (HBFCs) as alternatives is not encouraged, and steel, and heavy equipment. Water-based inks are perfluorocarbons (PFCs) should not be used in- used successfully for flexographic and rotogravure discriminately. laminates. High-solids coatings are now used for appliances, metal furniture, and a variety of con- Nonmedical Inhalants, Aerosols, Sterilants, struction equipment. Powder coatings are used for and Carbon Tetrachloride Not Used as a Solvent underground pipes, appliances, and automobiles. Ultraviolet light/electron beam (UV/EB) cured Nonmedical aerosol products. A variety of alterna- coatings and inks have been in limited use over tives to CFCs are used in nonmedical aerosol the past 20 years, but their use is increasing. They applications. Alternatives include hydrocarbons are now used in flexographic inks and coatings, (HCs); dimethyl ether (DME); compressed gases wood furniture and cabinets, and automotive such as carbon dioxide, nitrogen, and air; HCFC- applications. 142b and -22; HFC-134a -152a, and -227ea; and nonaerosol delivery means such as pump sprays, Aerosol solvent products. Methyl chloroform is solid sticks, roll-ons, brushes, and the like. Be- most often the solvent in aerosol applications, but cause hydrocarbons, DME, and HFC-152a are some CFC-113 has also been used. Most of these flammable, there may be products in which they applications can now be reformulated to avoid the cannot be used. In a manufacturing plant where use of ozone-depleting chemicals. With the excep- they are used for aerosol products, appropriate tion of water, methylene chloride, and some safety precautions will be required. HCFCs and non-ozone-depleting chlorinated solvents such as trichloroethylene and perchloroeth- Inhalant drug products. Some medical aerosol ylene, all of the alternatives to aerosol-applied products such as nasal preparations, local anes- solvents are more flammable than the solvents thetics, and antibiotics can be reformulated they replace. Alternative means of delivering the through the use of alternative propellants, me- solvent can be considered. chanical pumps, and so on. However, finding suitable alternatives to the CFCs in metered dose Other solvent uses of CFC-113, methyl chloroform, inhalers (MDIs) used by asthma sufferers has been and carbon tetrachloride. Specialized applications of a challenge. Alternatives that have been developed ozone-depleting solvents include drying of com- and proven to date include dry powder inhalers ponents, film cleaning, fabric protection, manu- and HFC-134a and -227. facture of solid-fuel rockets, laboratory testing and analysis, process solvents, and semiconductor Sterilants. A gas mixture of 88% CFC-12 and 12% manufacture. Some of these applications have ethylene oxide (EO) has been used by the medical been granted an exemption under the Montreal community to sterilize equipment and parts. Re- Protocol, but it is the consensus of the experts on placement alternatives include steam sterilization; the UNEP Solvents Technical Options Committee 100% EO; blends of carbon dioxide (10%) and EO that alternatives will be developed for all these (90%); formaldehyde; HCFC-124 (91.4%) and EO specialized uses. (8.6%); and other means such as gas plasma, chlo- 256 PROJECT GUIDELINES: POLLUTANT CONTROL TECHNOLOGIES rine dioxide, ozone, and radiation. Ethylene ox- Structural. Chemical alternatives include sulfuryl ide is toxic, mutagenic, flammable, and explosive fluoride and phosphine, as well as contact insec- and is a suspected carcinogen. Its use must there- ticides and rodenticides. Nonchemical alterna- fore be carefully controlled. tives are the same as for commodity fumigation.

Carbon tetrachloride (nonsolvent uses). Carbon Progress in Eliminating Ozone-Depleting tetrachloride (CTC) has been used as a feedstock Substances for the production of CFC-11 and –12. This application will cease with the closing of CFC produc- Significant progress has been made in eliminat- tion operations. CTC is also used as a feedstock ing ozone-depleting substances since the entry and processing agent for some pharmaceuticals into force of the Montreal Protocol in late 1987. and agricultural chemicals and in the production For example, in the aerosol industry, the use of of chlorinated rubber. The establishment of an al- ODSs has been reduced from 300,000 metric tons ternative for each application will be found only (t) globally in 1986 to 180,000 t in 1989 to, it is through product-specific research. estimated, less than 80,000 t in 1992. In the refrigeration sector, use of CFC refrigerants in in- Methyl Bromide dustrial countries dropped from 862,000 t in 1986 to 302,000 t in 1993. Globally, CFC refrigerant use Methyl bromide is used primarily as a fumigant. decreased from 1,133,000 t in 1986 to 643,000 t in Only 3.2% of the global sale of more than 75,000 1992. To help in managing the phase-out of ODS tons in 1992 was for nonfumigant purposes, as a refrigerants, a service industry has been estab- feedstock for chemical synthesis. The greatest lished in most countries that captures and puri- part was used to treat soil, to fumigate durables fies ODSs during the servicing of equipment. The and perishables, and to fumigate structures and removed ODSs are then used to service the on- transport equipment. From a conservation per- going needs of ODS-containing refrigeration and spective, technology exists to control the release cooling equipment until it has reached the end of methyl bromide when treating soil and of its useful life. In the fire protection sector, the crops. Molecular sieves are shown to capture focus has been on establishing halon banks to the methyl bromide that otherwise would have recondition and store halon that has been re- been lost to the atmosphere after batch fumi- moved from service and to make it available for gation and to regenerate the methyl bromide maintaining other installations that require confor use in subsequent batches. Alternatives to tinued use of halon until suitable replacements methyl bromide in each application area de- are developed. The foam plastics industry has scribed below. progressed from a global CFC use of 267,000 t in 1986 to 133,000 t in 1993—a reduction of 50%, in Soil. Chemical alternatives include 1,3- spite of a 45% increase in the size of the industry dichloropropene, dazomet, chloropicrin, metam during the same period. The phase-out of ozone- sodium, and selective contact insecticides and depleting solvents is well advanced in industrial herbicides. Nonchemical alternatives include countries, and users are drawing on stockpiled crop rotation, organic amendments, steam, solar solvents. In developing countries, CFC-113 use heating, biological control agents, cultural prac- has been largely halted, and production facilities tices, and plant breeding. are shutting down. The use of methyl chloroform is no longer increasing in these countries. Coun- Commodities. Chemical alternatives for crop tries such as Malaysia, Thailand, and Turkey have fumigation include phosphine and carbonyl sul- dramatically reduced solvent use. fide, as well as insecticides and rodenticides. It is important to note that the commercial sup- Nonchemical alternatives include irradiation, ply chain has had a role to play in the speed of controlled atmospheres utilizing nitrogen and phase-out of ODSs. In many instances, custom- carbon dioxide, and heat and cold. ers have asked their suppliers to implement a Ozone-Depleting Substances: Alternatives 257 phase-out program. These requests may originate to improve their environmental performance. because of labeling and tax legislation such as Manufacturers also understand that the dwin- that implemented by the United States or because dling supply of ODSs causes price increases that the customer has an environmental policy in will eventually make those products more expen- place that commits it to encourage its suppliers sive and less competitive.