c/EPA United States Environmental Protection Agency Industrial Environmental Research EPA-600/2-79-210m Laboratory December 1979 ... Cincinnati OH 45268 Vi ' Research and Development Status Assessment of Toxic Chemicals \ Trichloroethylene ------- RESEARCH REPORTING SERIES Research reports of the Office of Research and Development, U.S. Environmental Protection Agency, have been grouped into nine series. These nine broad cate- gories were established to facilitate further development and application of en- vironmental technology. Elimination of traditional grouping was consciously planned to foster technology transfer and a maximum interface in related fields. The nine series are: 1. Environmental Health Effects Research 2. Environmental Protection Technology 3. Ecological Research 4. Environmental Monitoring 5. Socioeconomic Environmental Studies 6. Scientific and Technical Assessment Reports (STAR) 7. Interagency Energy-Environment Research and Development 8. "Special" Reports 9. Miscellaneous Reports This report has been assigned to the ENVIRONMENTAL PROTECTION TECH- NOLOGY series. This series describes research performed to develop and dem- onstrate instrumentation, equipment, and methodology to repair or prevent en- vironmental degradation from point and non-point sources of pollution. This work provides the new or improved technology required for the control and treatment of pollution-sources to meet environmental quality standards. This document is available to the public through the National Technical Informa- tion Service, Springfield, Virginia 22161. ------- EPA-600/2-79-210m December 1979 STATUS ASSESSMENT OF TOXIC CHEMICALS: TRICHLOROETHYLENE by J. C. Ochsner T. R. Blackwood Monsanto Research Corporation Dayton, Ohio 45407 and W. C. Micheletti Radian Corporation Austin, Texas 78766 Contract No. 68-03-2550 Project Officer David L. Becker Industrial Pollution Control Dvision Industrial Environmental Research Laboratory Cincinnati, Ohio 45268 INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT U.S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268 ------- DISCLAIMER This report has been reviewed by the Industrial Environmental Research Laboratory - Cincinnati, U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the U.S. Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. 11 ------- FOREWORD When energy and material resources are extracted, processed, converted, and used, the related pollutional impacts on our environment and even on our health often require that new and increasingly more efficient pollution control methods be used. The Industrial Environmental Research Laboratory - Cincinnati (lERL-Ci) assists in developing and demonstrating new and im- proved methodologies that will meet these needs both efficiently and economically. This report contains a status assessment of the air emis- sions, water pollution, health effects, and environmental signi- ficance of trichloroethylene. This study was conducted to provide a better understanding of the distribution and character- istics of this pollutant. Further information on this subject may be obtained from the Organic Chemicals and Products Branch, Industrial Pollution Control Division. Status assessment reports are used by lERL-Ci to communicate the readily available information on selected substances to government, industry, and persons having specific needs and interests. These reports are based primarily on data from open literature sources, including government reports. They are indi- cative rather than exhaustive. David G. Stephan Director Industrial Environmental Research Laboratory Cincinnati iii ------- ABSTRACT Trichloroethylene is a colorless, volatile, nonflammable liquid at normal temperatures, which has a powerful solvent action on fats, greases, and waxes. For this reason, approximately 99% of all domestic trichloroethylene consumed per year is by metal and fabric degreasing operations. Trichloroethylene is also used in food processing, polyvinyl chloride production, fungicide manufacturing, textile treating, and medicinal anesthetizing. United States production in 1974 amounted to 176 x 103 metric tons and consumption was at 173.7 x 103 metric tons. However, these figures have been declining each year because of changes in production processes and restrictive legislation. The use of trichloroethylene as a solvent by degreasers is the major source of emissions. The four categories of degreasing operations (cold metal cleaning, open top vapor, conveyorized vapor, and fabric scouring) emit a total of 116.4 x 103 metric tons of trichloroethylene per year and open top vapor degreasers account for 55% of it. Emissions data from other sources is unavailable. Ambient concentrations in the atmosphere have been estimated to range from 2 ppt to 16 ppt in industrial areas. The EPA has also measured traces of trichloroethylene in the water of major cities and in some drinking water. However, the environmental impact of trichloroethylene is not fully understood. Emission control can best be accomplished through better equip- ment design and improved operating practices. The extent of control technology available to, or being used by, industrial producers or consumers is unknown. The use of trichloroethylene has been a matter of great concern to many governmental agencies. Evidence that trichloroethylene is a potent carcinogen has caused industry to avoid this chemi- cal for many applications. At present its use is expected to decline at 8%/yr through 1979. Based on information contained in this report, the following should be considered in future studies: 1) the environmental fate of trichloroethylene, 2) the extent of control technology in use, 3) information on emission quantities from production, transportation, or consumer end products, and 4) an assessment of trichloroethylene's future market. iv ------- This report was submitted in partial fulfillment of Contract 68-03-2550 by Monsanto Research Corporation under the sponsorship of the U.S. Environmental Protection Agency. This report covers the period November 1, 1977 to December 31, 1977. The work was completed as of January 20, 1978. v ------- CONTENTS Foreword iii Abstract iv Tables viii Conversion Factors and Metric Prefixes ix Acknowledgement x 1. Introduction 1 2. Summary 2 3. Source Description 5 Physical and chemical properties 5 Production 6 Process description 7 Uses 8 Transportation methods 9 4. Environmental Significance and Health Effects .... 11 Environmental significance 11 Health effects 14 5. Control Technology 17 Control methods 17 Efficiencies of the control methods 20 Economics of control methods 20 6. Regulatory Action 22 References 24 vn ------- TABLES Number Page 1 Trichloroethylene 4 2 Physical and Chemical Properties of Trichloro- ethylene 6 3 U.S. Trichloroethylene Capacity in 1975 7 4 1974 Degreasing Consumption of Trichloroethylene. 9 5 Emission Factors for Degreasing Operation Types . 12 6 Trichloroethylene Toxicity Data for Animals ... 16 7 Efficiencies of Control Methods 21 Vlll ------- CONVERSION FACTORS AND METRIC PREFIXES3 CONVERSION FACTORS To convert from to Multiply by Degree Celsius (°C) Degree Fahrenheit t° = 1.8 t° + 32 Kilogram (kg) Pound-mass (pound-mass avoirdupois) 2.204 Kilometer2 (km2) Mile2 3.860 x 10"1 Meter3 (m3) Foot3 3.531 x 101 Meter3 (m3) Gallon (U.S. liquid) 2.642 x 102 Metric ton Pound-mass 2.205 x 103 Pascal (Pa) Pound-force/inch2 (psi) 1.450 x 10 k METRIC PREFIXES Prefix Symbol Multiplication factor Example Kilo k 103 1 kg = 1 x 103 grams Milli m 10~3 1 mm = 1 x 10~3 meter Standard for Metric Practice. ANSI/ASTM Designation: E 380-76e, IEEE Std 268-1976, American Society for Testing and Materials, Philadelphia, Pennsylvania, February 1976. - 37 pp. ix ------- ACKNOWLEDGEMENT This report was assembled for EPA by Radian Corporation, Austin, TX, and Monsanto Research Corporation, Dayton, OH. Mr. D. L. Becker served as EPA Project Officer, and Dr. C. E. Frank, EPA Consultant, was principal advisor and reviewer. ------- SECTION 1 INTRODUCTION Trichloroethylene is a highly volatile chlorinated hydrocarbon which is widely used for degreasing of fabricated metal parts and, to a lesser extent, in cleaning fluids. Production and industrial use result in potential for extensive worker ex- posure. Trichloroethylene has been detected in ambient air and water in industrial areas, in food, and in human tissues. Tri- chloroethylene contributes to photochemical smog and is a sus- pected carcinogen in laboratory animals. This report on trichloroethylene (CHC1=CC12) provides available information on the health effects, environmental behavior and destiny, production, commercial uses, control technology, and present regulatory action for trichloroethylene. ------- SECTION 2 SUMMARY Trichloroethylene, CHC1=CC12/ is a colorless, sweet-smelling, volatile liquid at normal temperatures. Commercial grades of trichloroethylene contain stabilizers to prevent decomposition by oxygen. Approximately 99% of all domestic trichloroethylene is consumed by the metal and fabric degreasing trades. This is because of its nonflammability, volatility, and powerful solvent action for fats, greases, and waxes. Trichloroethylene is also used in food processing, polyvinyl chloride production, fungicide manufacturing, textile treating, and medicinal anesthetizing. United States production of trichloroethylene in 1974 amounted to 176 x 103 metric tons;3 however, it dropped in 1975 to 133 x 103 metric tons. The reason for this decline is because of changes in production processes and restrictive legislation. Evidence that trichloroethylene is a carcinogen is not likely to improve its market position. As of July 1975, only five companies were producing trichloro- ethylene. There are two basic processes depending upon whether the feedstock is acetylene or ethylene dichloride. Although the acetylene process has been the dominant method in the past, only 8% of the reported 1975 capacity relied on it. The common modes of shipping trichloroethylene are by barge (47.8%), tank car (40.3%) and tank truck (11.9%). Trichloroethylene emissions can occur from three sources: production, transportation, and consumption. The main exposure hazard is believed to be for users (consumption) rather than producers. Domestic consumption in 1974 was 173.7 x 103 metric tons. The use of trichloroethylene as a solvent by degreasers is the major source of emissions. Total annual emission quantities for degreasing operations are given in Table 1. Ambient concentrations in the atmosphere have been estimated to range from 2 ppt (parts per trillion) to 16 ppt in industrial al metric ton = 106 grams; conversion factors and metric system prefixes are presented in the prefatory pages of this report. ------- areas. The EPA has also measured traces of trichloroethylene in the water of major cities and in some drinking water. Due to the lack of ecological studies, the impact of trichloroethylene is not well known. The primary physiological response from exposure to trichloro- ethylene is depression of the central nervous system. In addi- tion, animal investigation has led to its classification as a suspected carcinogen. Emission control can be accomplished through better equipment design and improved operating practices. This is particularly true for metal degreasing operations where proper design and operation can decrease evaporation and other emissions. The extent of control technology in use is unknown. The use of trichloroethylene in metal degreasing operations and food processing has been a matter of concern to many governmental agencies. In late 1977, the Food and Drug Administration (FDA) considered a ban on the use of trichloroethylene in food process- ing because of its possible carcinogenic effects. Information on emissions, population exposed, control methods and regulatory action are summarized in Table 1. Areas in which information is not available are noted. Based upon information contained in this report, the following should be considered in future studies: • Emission quantities from production, transportation, or con- sumer use of products which may contain trichloroethylene. • The environmental fate of trichloroethylene and information on its transportation routes or degradation in air, water or soil. • The extent of control technology utilized by industrial producers or consumers and control efficiencies. • An assessment of trichloroethylene1s future use. • Economic substitute chemicals for all trichloroethylene uses. ------- TABLE 1. TRICHLOROETHYLENE Emission source Total emission quantity, 103 metric tons/yr Extent of problem Population exposed Production: Acetylene-based: Reactor reflux condenser vent Tail gas absorber vent Ethylene-based: None identified Transportation: Loading Transfer accidental spills Produced only at Taft, Louisiana by this process Produced at Deer Park and Freeport, Texas, and Baton Rouge and Lake Charles, Louisiana by this process Control method Regulation Incineration (95% efficiency) Treatment of aqueous waste streams Incineration (95% efficiency) Treatment of aqueous waste streams Proper operating practices Workplace exposure limit of 100 ppm at 8 hr (OSHA) Trichloroethylene is designated a priority pollutant under Federal Water Pollution Control Act Industrial use: Cold cleaners Open top vapor degreasers Conveyorized vapor degreasers Fabric scouring Food processing Miscellaneous Consumer use of end products: Public exposure due to use of products 19.5 63.5 25.9 7.5 _b _b Number of operations: 149,715 11,440 1,713 693 Proper design and operation of equipment (25% - 60% efficiency) Carbon absorption (95% - 100% efficiency) Incineration Liquid absorption Waste solvent reclamation (90% efficiency) Waste solvent landfills Workplace exposure limit of 100 ppm in 8 hr (OSHA) The FDA is considering a ban on use in foods, drugs, and cos- metic products. Present FDA limits on trichloroethylene in decaffeinated instant coffee, decaffeinated ground coffee, and spices are 10 ppm, 25 ppm, and 30 ppm, respectively. Extent of use is -mknown. Information not known. ------- SECTION 3 SOURCE DESCRIPTION The importance of trichloroethylene in the degreasing industry cannot be overemphasized. Its nonflammability, volatility, low cost, and powerful solvent action for fats, greases, and waxes. have made trichloroethylene a standard solvent for the cleaning of metal parts since World War II. Perchloroethylene has been used as a substitute for trichloroethylene and can be made utilizing similar process technology. The miscellaneous uses of trichloroethylene are expected to show the most growth through 1980. This will primarily be the result of increased usage in fungicide manufacture and polyvinyl chloride production. PHYSICAL AND CHEMICAL PROPERTIES At normal temperatures trichloroethylene (1,1,2-trichloroeth- ylene), CHC1=CC12, is a colorless, sweet-smelling, volatile liquid. In the absence of stabilizers, the liquid is slowly decomposed by oxygen in the atmosphere; the vapor, when the liquid phase is absent, is thermally stable at relatively high temperatures. All commercial grades of trichloroethylene con- tain added stabilizers (1). Stabilizers are usually added in quantitites of much less than 1% (by weight) to the trichloro- ethylene. There is a great variety of stabilizers including acetone, aniline, n-butane, diisopropylamine, isobutyl alcohol, phenol, and tetrahydrofuran. The exact mechanism of the sta- bilizing action is not yet fully understood. Some of the more important physical and chemical properties of trichloroethylene are given in Table 2 (1). (1) Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition, Vol. 5. John Wiley and Sons, Inc., New York, New York, 1969. pp. 183-195. ------- TABLE 2. PHYSICAL AND CHEMICAL PROPERTIES OF TRICHLOROETHYLENE (1) Physical state, STP Colorless liquid Molecular weight 131.4 Specific gravity, 20°/4°C 1.464 Boiling point, at 760 mm Hg, °C 86.7 Melting point, °C -37 Vapor density, air = 1.0, g/Jl 4.54 Latent heat of vaporization, bp, cal/g 57.2 Specific heat, 80°C, 1 atm, cal/(g)(°C): Liquid 0.225 Gas 0.156 Water solubility, g/100 g H2O: 25°C 0.11 60°C 0.125 PRODUCTION United States production of trichloroethylene in 1974 amounted to 176 x 103 metric tons, but it dropped in 1975 to 133 x 103 metric tons (2). U.S. demand for trichloroethylene was 195 x 103 metric tons in 1974 (3). Between 1964 and 1974 its growth in demand has been 1.25%/yr; however, it is predicted to drop 8%/yr through 1979 (3). The reason for this decline is two-fold. First, restric- tive legislation, such as the Los Angeles' Rule 66 and the 1970 Clean Air Act, has created a rather uncertain market for the chemical. Consequently, manufacturers have delayed the construc- tion of new plants or the expansion of existing capacity. Second, the acetylene-based process is now considered outmoded technology and these plants are being phased out of operation. In addition, evidence that trichloroethylene is a potent carcin- ogen has caused many industrial consumers to avoid this chemical for many applications. As of July 1975, only five companies were producing trichloro- ethylene in the United States. Table 3 summarizes the location, capacity, and feedstock of these plants (3). (2) Chemical Origins and Markets, Fifth Edition. G. M. Lawler, ed. Chemical Information Services, Stanford Research Institute, Menlo Park, California, 1977. 118 pp. (3) Chemical Profile: Trichloroethylene. Chemical Marketing Report, 208 (12) :9, 1975. ------- PROCESS DESCRIPTION There are two basic processes for manufacturing depending upon the feedstock. Trichloroethylene may be produced from acetylene or ethylene dichloride. Although the acetylene process has been the dominant method in the past, only 8% of the reported 1975 capacity relied on this process. In the acetylene process, acetylene is chlorinated to 1,1,2,2- tetrachloroethane, which is then dehydrochlorinated by reaction TABLE 3. U. S. TRICHLOROETHYLENE CAPACITY IN 1975 (3) Company and location Annual capacity,3 103 metric tons Feedstock Diamond Shamrock Chemical Company Electro Chemicals Division Deer Park, Texas Dow Chemical, USA Freeport, Texas Ethyl Corporation Industrial Chemicals Division Baton Rouge, Louisiana Hooker Chemicals and Plastics Corporation Electrochemical Division Taft, Louisiana PPG Industries, Inc. Industrial Chemical Division Lake Charles, Louisiana TOTAL 22.7 68.0 18.1 18.1 90.7 217.6 Ethylene Ethylene Ethylene Acetylene Ethylene plant capacities are very flexible, since at least one other chlorinated hydrocarbon can be made in the same equipment, depending on demand. (4) Sittig, M. Pollution Control in the Organic Chemical Industry. Noyes Data Corporation, Park Ridge, New Jersey, 1974. 304 pp. ------- with calcium hydroxide or by pyrolysis to yield trichloroethyl- ene. The process reactions are shown below (4) : +Ca (OH) 2 - ^ 2CHC1=CC12 + CaCl2 + 2H20 / trichloro- calcium water 2HC=CH + 4C12 - 2CHC12CHC12 — / ethylene chloride acety- chlo- 1,1,2,2- \ lene rine tetrachloro- \Pyro ysis — ^ 2CHC1=CC12 + 2HC1 ethane trichloro- hydrogen ethylene chloride In addition, perchloroethylene can be produced by oxychlorination of the ethylene dichloride as illustrated below (5) : 2CH2C1CH2C1 + 1.5 C12 + 1.75 O2 CHC1=CC12 + C12C=CC12 + 3.5 H2O The amount of perchloroethylene coproduced can be controlled according to the mole ratio of dichloride to chlorine in the feed. Other processes are technically available for the manufacture of trichloroethylene but are not commercially competitive with the two methods described above. USES Trichloroethylene is a powerful solvent for a large number of natural and synthetic organic substances. It is also nonflam- mable under conditions of normal use. Because of its powerful solvent action for fats, greases, and waxes and its nonf lammabil ity and volatility, trichloroethylene has become one of the most important industrial chlorinated solvents for vapor degreasing and dry cleaning. Vapor degreasers operate by condensation of vaporized solvent on the surface of the metal parts. The condensing solvent dissolves away oil and grease, and washes the parts as it drips down into a collection tank. Cold cleaners remove oil base impurities from metal parts in a batch loaded procedure that can include spraying, brushing, flushing, and immersion. The types of degreasing performed in the United States fall into four categories, which are 1) cold cleaning, 2) open top vapor (5) Lowenheim, F. A., and M. K. Moran. Faith, Keyes, and Clark's Industrial Chemical, Fourth Edition, John Wiley and Sons, Inc., New York, New York, 1975. pp. 605-607. 845-848. 8 ------- degreasing, 3) conveyorized vapor degreasing, and 4) fabric scouring (6). Each type of degreasing requires specific solvents. Trichloro- ethylene is needed in all four categories to some extent. Table 4 presents the 1974 consumption pattern for degreasing operations (6). Total domestic consumption of trichloroethylene in 1974 was 173.7 x 103 metric tons (6); therefore, degreasing operations represent 99% of total U.S. consumption. TABLE 4. 1974 DEGREASING CONSUMPTION OF TRICHLOROETHYLENE (6) Average Degreasing Number of consumption U.S. Total operation operations kg/yr 10 3 metric tons Cold cleaning Open top vapor Conveyorized vapor Fabric scouring TOTAL 149,715 11,440 1,713 693 293 7,165 17,780 21,664 43.8 82.0 30.7 15.0 171.5 Trichloroethylene was also used in food processing, chiefly in the extraction of caffeine for decaffeinated coffee, and in polyvinyl chloride production as a chain terminator. Other uses of trichloroethylene included fungicide manufacturing, textile treating, and medicinal anesthetizing. TRANSPORTATION METHODS Shipment of trichloroethylene can be by tank cars or tank trucks or in iron drums, cans, or bottles. It will not attack the com- mon metals, even in .the presence of moisture. Although no Department of Transportation shipping label is required, the Manufacturing Chemists Association does require a warning label (5). The common modes of transportation for trichloroethylene are by barge (47.8%), tank car (40.3%), and tank truck (11.9%) (7). (6) Hoogheem, T. J., P. J. Marn, and T. Hughes. Source Assess- ment: Solvent Evaporation - Degreasing. Contract 68-02- 1874, U.S. Environmental Protection Agency, Cincinnati, Ohio. (Final document submitted to the EPA by Monsanto Research Corporation, November 1977.) 180 pp. (7) Ocean Affairs Board, National Research Council. Assessing Potential Ocean Pollutants, Report 0-309-02325-4, U.S. Environmental Protection Agency and National Science Foundation, Washington, D.C., January 1975. 456 pp. ------- Trichloroethylene should be stored in a cool, dry, well-venti- lated area, away from acute fire hazards and direct sunlight. It should also be protected from excessive heat and sudden tempera- ture increases. Ultraviolet radiation and high temperatures can result in chemical degradation. 10 ------- SECTION 4 ENVIRONMENTAL SIGNIFICANCE AND HEALTH EFFECTS ENVIRONMENTAL SIGNIFICANCE Since detailed ecological studies have not yet been made, the environmental impact of trichloroethylene is not well known. Studies in England, however, have revealed that traces of tri- chloroethylene have been noted in samples of air, water, soil, and marine life (7). Precise transport routes or degradation processes were not suggested. Sources of Emissions Trichloroethylene emissions can occur from three sources: pro- duction, transportation, and consumption. In the acetylene- based process, there are two sources of air pollution, the vent on the reactor reflux condenser and the vent on the tail gas absorber (5). For the ethylene-based process, no specific process units have been identified as potential emission sources. There is general agreement that the main exposure hazard is for users rather than producers, since the chemical is made in a closed system. Pittsburgh Plate Glass and Dow Chemical companies report levels in their production plants well below 100 ppm (parts per million) (8). The quantity of trichloroethylene discharged from domestic transport is very difficult to evaluate. Emissions occur almost inevitably from loading and transfer operations and accidental spills (7). The major source of emissions resulting from trichloroethylene consumption can be attributed to its use as a solvent in open top and conveyorized vapor degreasers. Emissions occur due to diffu- sion and evaporation from the solvent bath, solvent carry-out on (8) Reactions Grow to Trichloroethylene Alert. Chemical & Engineering News, 53 (20) :41-43, 1975. 11 ------- parts, waste solvent evaporation, and exhaust (9). Table 5 pre- sents emission factors for the four categories of degreasing (6). These four categories of degreasing operations emit a total of 116.4 x 103 metric tons of trichloroethylene per year and open top vapor degreasers account for 55% of it. TABLE 5. EMISSION FACTORS FOR DEGREASING OPERATION TYPES (6) Emissions factor,9 Degreasing operation g/kg solvent consumed Cold cleaning 430 ± 30% Open top vapor 775 ± 30% Conveyor!zed vapor 850 ± 30% Fabric scouring 500 ± 30% Emission factors were calculated in Reference 6 by deter- mining the difference between the total amount of solvent utilized and the amount accountable through degreaser waste solvent activities. Thus, all solvents used within a specific degreasing operation are assumed to have the emission factor calculated for that operation. Environmental Levels Traces of trichloroethylene have been found in air and water samples taken in industrialized areas across the United States. Ambient concentrations in the atmosphere have been estimated by industry to range from 2 ppt to 16 ppt. Water concentrations have been measured at about 0.1 ppt (10). The U.S. Environmental Protection Agency has also measured traces of trichloroethylene in the water of major cities and in some drinking water (10, 11). There have also been several reports of contamination of wells and ground waters from careless disposal practices and accidents. Trichloroethylene levels in the soil are either unknown or the data are not readily available. (9) Control Techniques for Volatile Organic Emissions from Stationary Sources. (Draft report by Radian Corporation, AP-68), Contract 68-02-2608, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, July 1977. (10) Office of Toxic Substances. Summary Characterizations of Selected Chemicals of Near-Term Interest. EPA-560/4-76- 004, U.S. Environmental Protection Agency, Washington, D.C., April 1976. 50 pp. (11) Shakelford, W. M., and L. H. Keith. Frequency of Organic Compounds Identified in Water. EPA-600/4-76-062, U.S. Environmental Protection Agency, Athens, Georgia, December 1976. 629 pp. 12 ------- Secondary Effects Since the environmental fate of trichloroethylene is not com- pletely understood, assessing the secondary environmental effects of this chemical would depend more on speculation than on fact. The atmospheric photoxidation of trichloroethylene is the only environmental process for which any definitive data exist. The oxidation is believed to follow two main courses, the initial stages of which are the formation of the following oxygen compounds: C12C C12C-0 ClHcP^0 C1HC-0 (A) (B) During the oxidation, a small amount of hexachlorobutylene is formed by dimerization of the trichloroethylene. Over 80% of the initial oxidation products consists of compound (A). Com- pound (A) decomposes to yield dichloroacetyl chloride, ClaCHCOCl; compound (B) yields phosgene, carbon monoxide, and hydrogen chloride (1). * Very little information is available on the degradation of tri- chloroethylene in aqueous environments and soils. Various routes of chemical and biological degradation have been suggested but no definitive data exist. It has only been suggested that sig- nificant amounts of trichloroethylene evaporate from the water or soil and undergo photoxidation in the atmosphere; however, no definitive data have been reported (7). Population at Risk According to recent estimates (10), over 20,000 workers are directly exposed to trichloroethylene at five manufacturing plants and the many companies which routinely use solvent metal cleaning operations. In addition, the general public is indi- rectly exposed via inhalation of cleaning fluids and ingestion of foods, spices, and medicines from which undesirable components have been removed by trichloroethylene extraction. Foreign studies have detected residues ranging from 0.02 ppt to 22.0 ppt in human tissue (10). The Food and Drug Administration is currently determining if trichloroethylene can be detected in their food monitoring program. Reactions and Pathways in the Environment Since trichloroethylene has a low solubility, high vapor pres- sure, and relatively high photodegradation rate at sea level, it is not expected to accumulate in the atmosphere. The reported half-life of trichloroethylene in air ranges from 157 minutes 13 ------- (7) to eight hours (.10) . Trichloroethylene is oxidized by ozone to yield phosgene, hydrogen chloride, carbon monoxide, and dichloroacetylchloride (12). This autoxidation process is greatly enhanced by high temperatures and exposure to light, especially ultraviolet radiation. Even so, traces of trichloro- ethylene as high as 160 ppt have been noted in the industrial areas of England (7). More study is needed in the area of atmospheric degradation to solve this contradiction. The possibility of water pollution by trichloroethylene has recently become a matter of some concern. Mollusks around Port Erin, Isle of Man, where the waters are considered relatively unpolluted, were found to contain traces of trichloroethylene (7). This can be taken as an indication that trichloroethylene, which has a half-life in water on the order of months, is entering the biological food chain of the ocean. As of yet, adverse ecological effects have not been reported. HEALTH EFFECTS The primary physiological response from exposure to trichloro- ethylene is depression of the central nervous system. Prolonged moderate exposure may cause headaches and drowsiness. Acute exposure may lead to ventricular fibrillation resulting in cardiac failure and death (13). In addition, animal investiga- tion has led to the classification of trichloroethylene as a suspected carcinogen (14). Effects on Humans Nervous system depression is the dominant problem from acute exposure to trichloroethylene. Visual disturbances, mental con- fusion, fatigue, and sometimes nausea and vomiting are observed. The dangers in industry are accentuated by lack of coordination which may lead to poor manual manipulation and, consequently, unsafe mechanical operations. In some instances, a form of addiction has been observed in exposed workers. (12) Dorigan, J. Scoring of Organic Air Pollutants: Chemistry, Production and Toxicity of Selected Synthetic Organic Chemicals. (13) Sax, I. N. Dangerous Properties of Industrial Materials, Fourth Edition, Van Nostrand Reinhold, New York, New York, 1975. 1258 pp. (14) Registry of Toxic Effects of Chemical Substances. Christensen, H. E. and E. J. Fairchild, ed. Contract 210-75-0034, U.S. Department of Health, Education, and Welfare, Rockville, Maryland, June 1976. 1245 pp. 14 ------- Chronic exposure to low levels of trichloroethylene can cause growth depression, liver injury and kidney changes (15) although injury is not definitely established as a result of chronic exposure (13, 16). Even though moderate exposure does not have the same dramatic effect on the nervous system as acute exposure, symptoms similar to alcohol inebriation can occur. In one study, six students exposed to 110 ppm for two 4-hr periods separated by 1 1/2 hr showed significantly lower levels of performance in per- ception, memory, and manual dexterity tests (10). In April 1961, the American Conference of Governmental Industrial Hygienists established the threshold limit for trichloroethylene at 100 ppm (15). In addition to these limits and gradations, a variety of dosages and concentrations have been determined as a measure of the effect of trichloroethylene on humans. The lowest published oral lethal dose is 857 mg/kg. For inhalation, the lowest pub- lished toxic concentration is 160 ppm in 83 min and 110 ppm in 8 hr for a man (14). Studies have also determined that the body retains a significant amount of trichloroethylene for some period of time following exposure. The percentage of inhaled trichloroethylene that is exhaled ranges from 21% to 28% for a short exposure and 32% to 60% for a long exposure. The remainder is excreted or converted in some other way (unknown metabolites). Approximately 1.2% to 7.8% are recovered in the urine as trichloroacetic acid (15). In fact, the excretion of trichloroacetate is considered a reasonable index of exposure to trichloroethylene. Effects on Animals Experimental work done on animals is the major basis for the link between trichloroethylene and abnormalities in the liver and kidney. Experiments completed in 1951 showed that rats and rabbits exposed to 3,000 ppm of trichloroethylene for 7 hr/day, 5 days/wk during a 6-month period experienced an increase in liver and kidney weight. At lower concentrations (400 ppm), the increase in liver and kidney weight was still noticeable in rats, but much less dramatic than before. In addition, many animals, particularly the male of the species, showed less growth (15). Threshold dosages and concentrations for several animals are given in Table 6 (14) . (15) Industrial Hygiene and Toxicology, Volume II. F. A. Patty, ed. John Wiley and Sons, Inc., New York, New York, 1962. 2305 pp. (16) The Merck Index, M. Windholz, ed. Merck and Co., Inc., Rahway, New Jersey, 1976. 1313 pp. 15 ------- TABLE 3. TRICHLOROETHYLENE TOXICITY DATA FOR ANIMALS (14) Animal Rat Route Oral Inhalation Acute toxicity LD50b LCLO Dosage 4,920 mg/kg 8,000 ppm (4 hr) Mouse Oral Inhalation Intravenous Dog Oral LD Intraperitoneal LD Intravenous LD Rabbit Inhalation LC Subcutaneous LD LO 50 LO LO LO 135 g/kg (27 wk) 3,000 ppm (2 hr) 34 mg/kg 5,860 mg/kg 1,900 mg/kg 150 mg/kg 11,000 ppm 1,800 mg/kg Lethal dose; 50 percent kill. Lowest lethal concentration. 'Lowest toxic dose. Lowest lethal dose. 16 ------- SECTION 5 CONTROL TECHNOLOGY The available methods for controlling trichloroethylene emissions from production, transportation, and consumption operations will vary only slightly. Any major differences will be reflected as emission reductions economically achievable. CONTROL METHODS In almost all instances emission control can be accomplished through better equipment design and improved operating practices. This is particularly true for metal degreasing operations where proper design and operation can decrease evaporation and carry- out emissions. For the production of trichloroethylene the major emission sources are vents on the reactor reflux condenser and tail gas absorber, gaseous waste streams, and aqueous waste streams. The recommended method of control for vents and gaseous waste streams is incineration, preferably after mixing with another combustible fuel. Care must be exercised to assure complete combustion in order to prevent the formation of phosgene. In addition, an acid scrubber is necessary to remove the halogen acids produced. Control methods for aqueous waste streams would involve some type of separation process before final water dis- charge. Likely separation processes would be distillation, liquid-liquid extraction, and carbon adsorption. No details are available as to which, if any, are in use. For the transportation of trichloroethylene, the best means of emission reduction is proper operating practices. Care must always be taken when handling a chemical which might contaminate waters in the event of an accident. Spill prevention is essen- tial, but if a spill should occur, personnel should be prepared to properly contain the liquid. Any transfer operation will probably result in evaporation, but proper handling can reduce the amount so that vapor recovery is unnecessary. In any event, safety of the personnel requires that the transfer area be properly ventilated. Trichloroethylene is predominantly used as a solvent in open top vapor degreasers. Major emissions from these degreasers result from diffusion and evaporation from the solvent bath, solvent 5 17 ------- carry-out, exhaust, and waste solvent evaporation. The best method for reducing most of these emissions is simply proper design and operation. The cover is the single most important control device for open top vapor degreasers. They have been shown to reduce total emis- sions by 20% to 40%; effectiveness varies depending upon the frequency of cover use (6). Diffusion and evaporation losses can also be reduced by as much as 50% if the freeboard ratio is increased from 0.5 to 1.0 (9). The freeboard for an open top vapor degreaser is the air layer above the vapor zone which is cooled by a series of condensing coils that ring the internal wall of the jacket. The freeboard typically ranges from 50% to 70% of the width of the vapor degreaser and protects the solvent vapor zone from disturbance caused by air movement around the equipment. The freeboard ratio is defined as the freeboard height divided by the width of the air/solvent area and is usually 0.5 to 0.75. By increasing the freeboard ratio from 0.5 to 0.75 for an idle open top vapor degreaser, emission reductions of 25% to 30% are expected (9). Another design change is the use of refrigerated chillers. Re- frigerated chillers are a second set of condenser coils located slightly above the primary condenser coils of the degreasers. By creating a cold blanket of air immediately above the vapor zone, refrigerated chillers are estimated to reduce emission rates by approximately 40%. Actual tests on below freezing (-23°C to -29°C) units have achieved reductions of 28% to 62% (9). Collection and removal of trichloroethylene vapors by carbon adsorbers, incinerators, and liquid absorbers are also possible. Carbon adsorption is a well proven technology for the control of solvent emissions from degreasing operations, particularly for spray chambers where the area must be exhausted to protect the operator. Activated carbon has a very good capacity for common- ly used solvents such as trichloroethylene, perchloroethylene, and 1,1,1-trichloroethane. Although carbon adsorption units can remove 95% to essentially 100% of the organic input to the bed, reductions in the total solvent emission are only 40% to 65%. Many systems achieve less than 40% emission reduction because of poor inlet collection efficiency and an improperly maintained or adjusted carbon adsorber (9). Although incineration is widely used for emission control in many industries, special problems make it an unattractive option for degreasing operations. For instance, chlorinated hydro- carbons present in the organic solvents are pyrolized at incin- erator temperatures releasing chlorine, hydrochloric acid, and phosgene. Removal of these gases from the incinerator exhaust requires additional gas cleaning equipment. Cold cleaners often use solvents of low volatility, so combustion requires the use of supplemental fuel. These factors, along with the high capital cost, make incineration an unlikely choice for emission control. 18 ------- Liquid absorption is also a well-known method of controlling organic emissions, but has design problems which make it an impractical alternative. For example, trichloroethylene vapors are easily absorbed by mineral oil. The absorption column is operated at 30°C and the column effluent contains about 120 ppm mineral oil vapors. In essence, one emission problem is ex- changed for another. Chilling the absorbing fluid would reduce the concentration of mineral oil in the exhaust gas, but would also lead to ice formation within the column and greatly in- crease the energy requirement. Carry-out emissions can be appreciable if proper materials handling procedures are not followed. While drainage facilities are used to control emissions from cold cleaners, no special controls have been reported for open top vapor degreasers. Exhaust emissions result when exhaust rates for open top vapor degreasers are set too high. The average exhaust rate is 0.25 m3/s m2 of degreaser opening (9). However, this rate is sometimes exceeded in order to comply with OSHA regulations on solvent threshold limit values (TLV®). For trichloroethylene the TLV is 100 ppm or 535 mg/m3 (17). Emissions from waste solvent evaporation occur in a number of different ways, none of which can easily be monitored or quanti- fied. Approximately one-third of the total solvent emissions from degreasing operations are estimated to be from waste solvent evaporation. Recommended methods of waste solvent disposal include reclamation, direct incineration, and chemical landfills. Solvent reclamation is considered the best method for reducing emissions from evaporation of waste solvent since almost 90% of the solvent is recovered as usable product. Reclamation can be done through a private contractor or in-house distillation. Private contractors usually collect waste solvent, distill it, and return the reclaimed portion. Users are charged about half the market value of the solvent. This method is economically attractive in industrial areas where users are not separated by large distances. In-house distillation is common among users employing multiple open top degreasers. One report states that the annual operating costs of an in-house reclamation system are recovered from the first 1.32 m3 of chlorinated solvents distilled. In-house (17) TLVs® Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes for 1976. American Conference of Governmental Industrial Hygienists, Cincinnati, Ohio, 1976. 94 -pp. 19 ------- distillation involves some significant problems. These include disposal of distillate bottoms containing metals and sludge, decomposition of chlorinated solvents, formation of azeotropes, and occurrence of adverse chemical reactions. Direct incineration is not as desirable as reclamation since it does not result in a usable product. Furthermore, it may require substantial amounts of supplemental fuel. Incineration requires temperatures of 1200°C, sufficient residence time (about 2 s), and exhaust gas cleaning equipment. Although capital invest- ments are high, operating costs have been estimated at less than 4.4C/kg of waste solvent incinerated. Most chemical landfills are presently inadequate as waste solvent disposal methods. Chemical landfills would be suitable if steps were taken to eliminate evaporation and permeation. One method under consideration involves sealing the waste solvent in lined drums and surrounding these drums with 1.2 m to 6.1 m of packed clay. This method has not been demonstrated. EFFICIENCIES OF THE CONTROL METHODS The efficiency of any specific control method will depend on a number of operating variables such as temperature, residence time, and the amount and nature of the waste gas. In addition, adequate maintenance of emission control equipment is a prereq- uisite for proper operation. The efficiencies of the control methods discussed and documented in the previous section are summarized in Table 7 (9). No information is available on the extent to which any of the control measures discussed are being utilized in plants practicing degreasing (6). ECONOMICS OF CONTROL METHODS Estimating the economics of a particular control method is a very complicated matter. Proper operation and maintenance of manufacturing equipment and careful handling and storage of tri- chloroethylene result in minor costs, if any. The costs of add-on pollution abatement equipment can cover a broad spectrum and will depend on the amount and nature of the waste, the difficulty in retrofitting any necessary equipment, and the recurrent use of additional materials such as catalyst, supplemental fuel, or activated carbon. No definitive data for trichloroethylene are presently available. A general discussion of environmental control methods for volatile organic emissions can be found in the recently revised draft edition of EPA pub- lication AP-68 (9) . 20 ------- TABLE 4. EFFICIENCIES OF CONTROL METHODS (9)S ~~~ ~~~ ~ Removal Control method efficiency, Production of trichloroethylene Incineration of vent and waste gas 95+ Treatment of aqueous waste streams Transport of trichloroethylene Proper handling and storage Consumption of trichloroethylene Increased freeboard ratio on open top vapor degreasers 25 to 50 Refrigerated chillers 28 to 62 Carbon adsorption 95 to 100 Waste gas incineration 95+ Liquid absorption Waste solvent reclamation 90 Waste solvent incineration 95+ Waste solvent landfills aBlanks indicate information unknown or unavailable. 21 ------- SECTION 6 REGULATORY ACTION The use of trichloroethylene in metal degreasing operations and food processing has been a matter of concern to many governmental agencies. Perhaps the most restrictive legislation has been the Los Angeles Air Pollution Control District's Rule 66 which was passed in December 1974. According to Rule 66, not more than 20% by volume of trichloroethylene could be used in formulating solvent blends that are evaporated into the atmosphere. In addition, the sum of all restricted solvents in the final solvent blend could not exceed 20% by volume. Rule 66 also prohibited vapor degreasing plants from discharging into the atmosphere more than 17 kg of trichloroethylene in any single day, or more than 3.6 kg of trichloroethylene in any one hour, unless the discharge had been reduced by at least 85%. Amendments to Rule 66 have been even/!more restrictive. Although Rule 66 ap- plies to only a small portion of the country, environmentally conscious communities have adopted parts of it for their own use. Since trichloroethylene contributes to photochemical smog, State Implementation Plans (SIP) provide a mechanism for limiting emissions. Discharge permits limiting biological oxygen demand (BOD), chemical oxygen demand (COD), and suspended solids also provide some control over effluent discharges. Detailed health, environmental, and economic analyses are being conducted to determine the necessity of revisions to these regulations. In 1973, the National Institute for Occupational Safety and Health, (NIOSH) recommended that the Occupational Safety and Health Administration (OSHA) establish worker exposure limits at 100 ppm trichloroethylene with a peak concentration of 150 ppm trichloroethylene. In July 1975, the American Conference of Governmental Industrial Hygienists determined that there is insufficient evidence to warrant any change in the existing tri- chloroethylene TLV set at 100 ppm. The maximum allowable con- centration is 200 ppm provided the TLV does not exceed 100 ppm. For a maximum cumulative exposure of 5 min in any 2-hr period, the acceptable maximum peak above the maximum allowable con- centration is 300 ppm. In April 1975, a "memorandum of alert" was issued by the National Cancer Institute (NCI) concerning the link between trichloro- ethylene and cancer in mice. The NCI has begun studies to 22 ------- determine effects on humans. In addition, trichloroethylene producers have conducted epidemiological studies, long-term animal feeding studies, and long-term animal inhalation studies. And an in-depth literature survey has also been completed for the Manufacturing Chemists Assocation (MCA). The Food and Drug Administration (FDA) has been urged to ban the use of trichloroethylene in food processing because of its pos- sible carcinogenic effects. At present the FDA limits trichloro- ethylene to 10 ppm in decaffeinated instant coffee, 25 ppm in decaffeinated ground coffee, and 30 ppm in spices (8). The Commissioner of Food and Drugs expects to issue final regula- tions ba,sed on proposals no later than January 25, 1978 (18). These proposals would amend regulations by prohibiting trichloro- ethylene in human food, drugs, and cosmetic products or in animal food and drugs, because it may pose a risk of cancer in man or animals. Trichloroethylene has been designated a priority pollutant under the Federal Water Pollution Control Act. (18) Code of Federal Regulations 21 - Food and Drug Administra- tion - Parts 73, 172, 173, 175, 177, 189, 250, 500, 510, 700 - Trichloroethylene - Proposed Rules. Federal Register, 42(187):49464-49471, 1977. 23 ------- REFERENCES 1. Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition, Vol. 5. John Wiley and Sons, Inc., New York, New York, 1969. pp. 183-195. 2. Chemical Origins and Markets, Fifth Edition. G. M. Lawler, ed. Chemical Information Services, Stanford Research Institute, Menlo Park, California, 1977. 118 pp. 3. Chemical Profile: Trichloroethylene. Chemical Marketing Reporter, 208(12):9, 1975. 4. Sittig, M. Pollution Control in the Organic Chemical Industry. Noyes Data Corporation, Park Ridge, New Jersey, 1974. 304 pp. 5. Lowenheim, F. A., and M. K. Moran. Faith, Keyes, and Clark's Industrial Chemical, Fourth Edition, John Wiley and Sons, Inc., New York, New York, 1975. pp. 605-607, 845-848. 6. Hoogheem, T. J., P. J. Marn, and T. Hughes. Source Assess- ment: Solvent Evaporation - Degreasing. Contract 68-02- 1874, U.S. Environmental Protection Agency, Cincinnati, Ohio. (Final document submitted to the EPA by Monsanto Research Corporation, November 1977.) 180 pp. 7. Ocean Affairs Board, National Research Council. Assessing Potential Ocean Pollutants, Report 0-309-02325-4, U.S. Environmental Protection Agency and National Science Foundation, Washington, D.C., January 1975. 456 pp. 8. Reactions Grow to Trichloroethylene Alert. Chemical & Engineering News, 53 (20) :41-43, 1975. 9. Control Techniques for Volatile Organic Emissions from Stationary Sources. (Draft report by Radian Corporation, AP-68), Contract 68-02-2608, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, July 1977. 10. Office of Toxic Substances. Summary Characterizations of Selected Chemicals of Near-Term Interest. EPA-560/4-76- 004, U.S. Environmental Protection Agency, Washington, D.C., April 1976. 50 pp. 24 ------- 11. Shackelford, W. M., and L. H. Keith. Frequency of Organic Compounds Identified in Water. EPA-600/4-76-062, U.S. Environmental Protection Agency, Athens, Georgia, December 1976. 629 pp. 12. Dorigan, J. Scoring of Organic Air Pollutants: Chemistry, Production and Toxicity of Selected Synthetic Organic Chemicals. 13. Sax, I. N. Dangerous Properties of Industrial Materials, Fourth Edition. Van Nostrand Reinhold, New York, New York, 1975. 1258 pp. 14. Registry of Toxic Effects of Chemical Substances. Christensen, H. E. and E. J. Fairchild, ed. Contract 210- 75-0034, U.S. Department of Health, Education, and Welfare, Rockville, Maryland, June 1976. 1245 pp. 15. Industrial Hygiene and Toxicology, Volume II. F. A. Patty, ed. John Wiley and Sons, Inc., New York, New York, 1962. 2305 pp. 16. The Merck Index, M. Windholz, ed. Merck and Co., Inc., Rahway, New Jersey, 1976. 1313 pp. 17. TLVs® Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes for 1976. American Conference of Governmental Industrial Hygienists, Cincinnati, Ohio, 1976. 94 pp. 18. Code of Federal Regulations 21 - Food and Drug Administra- tion - Parts 73, 172, 173, 175, 177, 189, 250, 500, 510, 700 - Trichloroethylene - Proposed Rules. Federal Register, 42(187) :49464-49471, 1977. 25 ------- TECHNICAL REPORT DATA (Please read Instructions on the reverse before completing) REPORT NO. EPA-600/2-79-210m 3. RECIPIENT'S ACCESSION NO. 4. TITLE AND SUBTITLE 5. REPORT DATE December 1979 issuing date Status Assessment of Toxic Chemicals: Trichloroethylene 6. PERFORMING ORGANIZATION CODE '. AUTHOR(S) T.R. Blackwood, J.C. Ochsner W.C. Micheletti 8. PERFORMING ORGANIZATION REPORT NO. 9. PERFORMING ORGANIZATION NAME AND ADDRESS Monsanto Research Corp Radian Corp 1515 Nichols Road 8500 Shoal Creek Blvd Dayton, Ohio 1^07 P.O. Box 99^8 Austin, Texas 78766 10. PROGRAM ELEMENT NO. 1AB60U 11. CONTRACT/GRANT NO. 68-03-2550 12. SPONSORING AGENCY NAME AND ADDRESS Industrial Environmental Research Lab« - Cinn, OH Office of Research and Development U.S. Environmental Protection Agency Cincinnati, Ohio 1+5268 13. TYPE OF REPORT AND PERIOD COVERED Task Final 11/77 - 12/77 14. SPONSORING AGENCY CODE EPA/600/12 15. SUPPLEMENTARY NOTES lERL-Ci project leader for this report is Dr. Charles Frank, 513-68i|-UU8l. 16. ABSTRACT The production processes, uses, and properties of trichloroethylene are revealed in this report. The sources and amounts of trichloro- ethylene pollution are identified as well as the health effects and environmental significance. Current control technologies are identi- fied, along with assessments on their cost and effectiveness. Recent regulatory actions are explained and areas where further study is called for are identified. 17. KEY WORDS AND DOCUMENT ANALYSIS DESCRIPTORS b.IDENTIFIERS/OPEN ENDED TERMS C. COS AT I Field/Group Hydrocarbons, aliphatic hydrocarbons, Ethylene Trichloroethylene, De- greasing, Anesthetic, Food Processing Textile Treatment, Polyvinyl Chloride Production, Fungicides, Halogenated Aliphatics 68A 68D 68G 18. DISTRIBUTION STATEMENT Release to Public 19. SECURITY CLASS (ThisReport) Unclassified 21. NO. OF.PAGES 36 20. SECURITY CLASS (This page) Unclassified 22. PRICE EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION IS OBSOLETE 26 TV U S. GOVERNMENT PRINTING OFFICE: 1980 -657-146/5516 ------- |