EPA/600/R-00/099

March 2001

SOURCES, EMISSION AND EXPOSURE FOR 

TRICHLOROETHYLENE (TCE)

 AND RELATED CHEMICALS

National Center for Environmental Assessment–Washington Office

Office of Research and Development

U.S. Environmental Protection Agency

Washington, DC 20460
ii

DISCLAIMER

This report has been reviewed in accordance with U.S. Environmental Protection Agency

policy and approved for publication. Mention of trade names or commercial products does not

constitute endorsement or recommendation for use.
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TABLE OF CONTENTS

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii

AUTHORS, CONTRIBUTORS, AND REVIEWERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

SECTION A. SUMMARY AND INTRODUCTION ..................................1

SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

SECTION B. PARENT COMPOUNDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.0 TRICHLOROETHYLENE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.3.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 23

1.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

1.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

1.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.0 TETRACHLOROETHYLENE (PERCHLOROETHYLENE) . . . . . . . . . . . . . . . . . . . . 30

2.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
TABLE OF CONTENTS (continued)

iv

2.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 40

2.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

2.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

2.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

2.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.0 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM) . . . . . . . . . . . . . . . . . . . . . 44

3.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 44

3.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

3.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

3.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

3.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 52

3.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

3.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

3.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

3.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4.0 1,2-DICHLOROETHYLENE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

4.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

4.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

4.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

4.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
TABLE OF CONTENTS (continued)

v

4.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 62

4.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

4.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

5.0 CIS-1,2-DICHLOROETHYLENE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

5.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

5.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

5.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

5.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 70

5.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

6.0 TRANS-1,2-DICHLOROETHYLENE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

6.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 71

6.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

6.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

6.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

6.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

6.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

6.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

6.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

6.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

6.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

6.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

6.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

6.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

6.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 76

6.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
TABLE OF CONTENTS (continued)

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6.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

6.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

7.0 1,1,1,2-TETRACHLOROETHANE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

7.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 77

7.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

7.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

7.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

7.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

7.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

7.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

7.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

7.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

7.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

7.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

7.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

7.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

7.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 81

7.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

7.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

7.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

7.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

8.0 1,1-DICHLOROETHANE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

8.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 83

8.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

8.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

8.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

8.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

8.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

8.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

8.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

8.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

8.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

8.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

8.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

8.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

8.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 88

8.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

8.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

8.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

8.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

SECTION C. METABOLITES OF TRICHLOROETHYLENE 

AND PARENT COMPOUNDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
TABLE OF CONTENTS (continued)

vii

9.0 CHLORAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

9.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 91

9.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

9.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

9.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

9.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

9.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

9.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

9.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

9.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

9.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

9.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

9.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

9.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

9.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . . 96

9.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

9.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

9.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

9.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.0 CHLORAL HYDRATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

10.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . 98

10.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

10.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

10.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

10.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

10.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

10.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

10.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . 102

10.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

11.0 MONOCHLOROACETIC ACID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

11.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . 103

11.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

11.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

11.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

11.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

11.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
TABLE OF CONTENTS (continued)

viii

11.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

11.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

11.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

11.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

11.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

11.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

11.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

11.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . 107

11.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

12.0 DICHLOROACETIC ACID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

12.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . 109

12.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

12.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

12.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

12.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

12.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

12.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . 112

12.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

12.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

12.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

12.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

13.0 TRICHLOROACETIC ACID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

13.1 CHEMICAL AND PHYSICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . 113

13.1.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

13.1.2 Formula and Molecular Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

13.1.3 Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

13.1.4 Technical Products and Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

13.2 PRODUCTION AND USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

13.2.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

13.2.2 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

13.2.3 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

13.3 POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

13.3.1 Natural Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

13.3.2 Occupational . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

13.3.3 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
TABLE OF CONTENTS (continued)

ix

13.4 HUMAN EXPOSURE AND POPULATION ESTIMATES . . . . . . . . . . . . . . 118

13.4.1 General U.S. Population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

13.4.2 Occupational Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

13.4.3 Consumer Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

13.5 CHAPTER SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

14.0 DICHLORO-VINYL CYSTEINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
x

LIST OF TABLES

Table A-1. Summary of Potential Exposure Pathways and Potentially 

Exposed Populations ...............................................5

Table A-2. Preliminary Dose Estimates of TCE and Related Chemicals ................8

Table A-3. Summary of U.S. Production Data .....................................9

Table 1-1. Annual Releases of Trichloroethylene in the U.S. (lbs) . . . . . . . . . . . . . . . . . . . . 16

Table 1-2. Concentrations of Trichloroethylene in Ambient Air . . . . . . . . . . . . . . . . . . . . . 17

Table 1-3 Mean TCE Air Levels Across Monitors by Year . . . . . . . . . . . . . . . . . . . . . . . . . 18

Table 1-4 Mean TCE Air Levels Across Monitors by Land 

Setting and Use (1985 to 1998) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Table 1-5 Modeled TCE Air Concentrations in Continental U.S. for 1990 . . . . . . . . . . . . . 18

Table 1-6. Concentrations of Trichloroethylene in Water . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Table 1-7. TCE Levels in Whole Blood by Population Percentile . . . . . . . . . . . . . . . . . . . . 22

Table 1-8. Modeled Exposure Estimates for TCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Table 1-9. Comparison of Measured and Modeled TCE Concentrations . . . . . . . . . . . . . . . 25

Table 1-10. Trichloroethylene Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Table 2-1. Releases of Tetrachloroethylene (lbs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Table 2-2. Concentrations of Tetrachloroethylene in Ambient Air . . . . . . . . . . . . . . . . . . . . 34

Table 2-3. Concentrations of Tetrachloroethylene in Water . . . . . . . . . . . . . . . . . . . . . . . . . 35

Table 2-4. Tetrachloroethylene Levels in Whole Blood by Population 

Percentile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Table 2-5. Modeled Exposure Estimates for Tetrachloroethylene . . . . . . . . . . . . . . . . . . . . 38

Table 2-6. Comparison of Measured and Modeled Perchloroethylene 

Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Table 2-7. Tetrachloroethylene (Perchloroethylene) Summary . . . . . . . . . . . . . . . . . . . . . . . 43

Table 3-1. Releases of 1,1,1-Trichloroethane (lbs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table 3-2. Level of 1,1,1-Trichloroethane in Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 3-3. 1,1,1-Trichloroethane in Common Household Products . . . . . . . . . . . . . . . . . . . 54

Table 3-4. 1,1,1-Trichloroethane (Methyl Chloroform) Summary . . . . . . . . . . . . . . . . . . . . 55

Table 4-1. 1,2-Dichloroethylene Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Table 7-1. 1,1,1,2-Tetrachloroethane Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Table 8-1. 1,1-Dichloroethane Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Table 9-1. Concentrations of Chloral (As Chloral Hydrate) 

in Drinking Water in the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Table 9-2. Chloral Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Table 10-1. Chloral Hydrate Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Table 11-1. Release of Chloroacetic Acid (lbs/yr) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Table 11-2. Monochloroacetic Acid Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Table 12-1. Concentrations of Dichloroacetic Acid in Water . . . . . . . . . . . . . . . . . . . . . . . . 111

Table 12-2. Dichloroacetic Acid Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Table 13-1. Concentrations of Trichloroacetic Acid in Water . . . . . . . . . . . . . . . . . . . . . . . 116

Table 13-2. Trichloroacetic Acid Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
xi

LIST OF FIGURES

Figure A-1. Trichloroethylene, Related Parent Compounds, 

and Their Metabolites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 1-1. Modeled TCE Levels in Air from Cumulative 

Exposure Project by Census Tract, New Jersey . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 1-2. Frequency of NPL Sites with Trichloroethylene Contamination . . . . . . . . . . . . . 28

Figure 2-1. Concentration of Tetrachloroethylene in Blood at 

Selected Population Percentiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 2-2. Frequency of NPL Sites with Tetrachloroethylene Contamination . . . . . . . . . . . 42

Figure 3-1. Concentration of 1,1,1-Trichloromethane in Blood at 

Selected Population Percentiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Figure 3-2. Frequency of NPL Sites with 1,1,1-Trichloromethane Contamination . . . . . . . . 53

Figure 4-1. Frequency of NPL Sites with 1,2-Dichloroethene (Unspecified)

Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Figure 8-1. Frequency of NPL Sites with 1,1-Dichloroethane Contamination . . . . . . . . . . . 89
xii

PREFACE

This document was based mostly on the report, “Sources, Emission and Exposure for

Trichloroethylene (TCE)” which was prepared in August 1997 by the Versar, Inc. of Springfield,

Virginia under U.S. Environmental Protection Agency (EPA) Contract No. 68-D5-0051. 

Additional information was later added/updated, especially for the Trichloroethylene chapter.

This document is published as a state-of-the-science report on the exposure assessment of

TCE, its metabolites and other related chemicals known to produce similar metabolites. A

summary of much of the information contained in this report was also published in

Environmental Health Perspectives, Supplements, May 2000 and underwent the peer review

process required by the journal. 

The scientific literature search for this assessment is generally current through January

1997, although a number of more recent publications on key topics have been included.
xiii

AUTHORS, CONTRIBUTORS, AND REVIEWERS

Authors

This report was prepared by Versar, Inc. of Springfield, VA, for the National Center for

Environmental Assessment-Washington Office (NCEA-W) of EPA’s Office of Research and

Development. Dr. Chieh Wu (NCEA-W) served as the Work Assignment Manager for this

contract as well as a contributing author. John Schaum (NCEA-W) was also a contributing

author.

Reviewers

A summary of this report was published in Environmental Health Perspective, Volume

108, Supplement 2 in May 2000 by Wu and Schaum. This journal sponsored a peer review of

this article by their independent reviewers. Other reviewers of this document are listed below:

EPA reviewers:

Cheryl Scott

National Center for Environmental Assessment

Mike Dusetzina

Office of Air Quality Planning and Standards

External reviewers:

Dr. C.P. Huang

Chair and Distinguished Professor of Environmental Engineering

University of Delaware

Dr. Uwe Schneider 

Environmental Quality Branch

Environment Canada

Dr. Mildred Williams-Johnson

Agency for Toxic Substances and Disease Registry

U.S. Department of Health and Human Services

Acknowledgments

The authors wish to thank Cheryl Scott and Mike Dusetzina for their review and

comments of the draft report, and Susan Perlin of NCEA-W and David Wong of George Mason

University for their assisstance in the use of the Geographic Information System (GIS) modeling

to map the air concentrations in New Jersey. The authors also would like to thank all the

reviewers for their time and efforts.
1

SECTION A. SUMMARY AND INTRODUCTION

SUMMARY

This report is an exposure assessment of Trichloroethylene (TCE), its metabolites, and

other chemical compounds known to produce identical metabolites. In addition to TCE, other

parent compounds considered here are 1,1,1-trichloroethane (methyl chloroform),

tetrachloroethylene (PCE or PERC), 1,2-dichloroethylene (cis-, trans-, and mixed isomers),

1,1,1,2-tetrachloroethane, and 1,1-dichloroethane. The metabolites are chloral, chloral hydrate,

monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, and dichloro-vinyl cysteine

(DCVC). Although listed here, no information was found for the metabolite, DCVC.

The parent compounds are used in many diverse manufacturing industries such as food

processing, textiles, wood products, furniture and fixtures, paper, printing and publishing,

chemicals, petroleum, rubber, leather, stone and clay, primary metals, fabricated metals,

industrial machinery, electronics, and transportation equipment. They are primarily used as

solvents, carriers, or extractants; in dry cleaning of textiles; in metal cleaning and degreasing; in

textile manufacturing; as insulating fluids/coolants; and as chemical intermediates. The

metabolites have more restricted uses in industry as chemical intermediates, herbicides, and

pharmaceuticals.

The major routes of exposure for these chemicals are inhalation, ingestion, and dermal

absorption. The following paragraphs summarize available information concerning the general

population, occupational, and consumer exposure to these chemicals. A summary of the

potential exposure pathways and potential exposed populations for each chemical is presented in

Table A-1. Although inhalation seems to be the dominant route of exposure for most of the

chemicals, exposure can also occur through the ingestion of contaminated foods and drinking

water and through dermal contact (spills). Using media levels of the chemicals considered here,

one may predict the range of estimated exposures and the estimated range of daily doses. These

values are presented in Table A-2.

More research is needed to assess the exposure of these chemicals for the nonoccupational population (IARC, 1995; ATSDR, 1990, 1995, 1996a,b, 1997a,b). Most of the

monitoring data for humans are from occupational studies of specific workers exposed to the

chemical. Current data are needed for all chemicals for production, use in consumer products,

releases, and the efficiency of current disposal practices. Additionally, more data are needed on

the degradation of these chemicals in groundwater (specifically TCE, PCE, 1,1,1-trichloroethane,

and 1,2-dichloroethylene) and their rates of transformation in the soil. Current data to

characterize the levels of these chemicals in air, water, soil, and food also are needed. Current

monitoring data for these media will aid in the assessment of exposure for the general population,

especially persons living near waste sites. Biological monitoring data are also needed for

humans. Because TCE and PCE have been detected in breast milk samples (NHANES III, 1997)

of the general population, children ages 12 months and less who ingest breast milk may

potentially be exposed. Unspecified levels of TCE have been found in breast milk, however,

levels of PCE detected have ranged up to 43 μg/l in the general population. According to NAS
2

(1991), in 1989, the initiation of breast-fed newborn infants in the hospital was reported to 52.2

percent and by age 5-6 months, only 19.6 percent of the infants were breast-fed. Since some of

these chemicals (e.g., TCE and PCE) are present in soil, children may be exposed through

activities such as playing in or ingesting soil. Table A-3 presents the production data

(production, import, and export). As shown in this table, however, most of the production data

are old or non-existent.

Trichloroethylene

The general U.S. population is exposed via inhalation, ingestion, or dermal pathways. 

The most important pathways appear to be inhalation of contaminated ambient air and ingestion

of contaminated drinking water. Because of pervasiveness of TCE in the environment, most

people are exposed to low levels of TCE. Occupational exposure results primarily from its use

as a degreasing or metal cleaning agent. Workers in the vapor degreasing industry are exposed to

the highest levels through inhalation. Consumers are exposed through their use of wood stains,

varnishes, finishes, lubricants, adhesives, typewriter correction fluid, paint removers, and

cleaners that contain TCE. Levels of TCE in consumer products appear to be declining. 

Elevated exposure may occur to people living near waste facilities, those being exposed through

occupational activities, and residents of some urban and industrial areas where TCEcontaminated media occur. Since TCE has been detected in breast milk, nursing infants may be

exposed via this pathway.

Tetrachloroethylene (Perchloroethylene; PCE)

The general U.S. population is exposed to PCE via inhalation and ingestion. The most

important pathways appear to be inhalation of contaminated ambient air (including indoor air)

and ingestion of contaminated drinking water. Dermal exposure does not appear to be important. 

The greatest chance of exposure is occupational, primarily through inhalation, especially in the

dry cleaning industry. Consumers may be exposed through the use of adhesives, water

repellents, fabric finishes, spot removers, and wood cleaners. Since PCE has been detected in

breast milk, nursing infants may be exposed via this pathway.

1,1,1-Trichloroethane (methyl chloroform)

The general U.S. population is exposed to this chemical via inhalation of ambient air

(including indoor air). Exposure can also occur through ingestion of contaminated foods and

drinking water and through dermal contact. Exposure from commercial products may be more

significant than exposure resulting from industrial releases. Occupational exposure results from

degreasing, electric component manufacture, mixing and application of commercial resins, spray

painting and gluing. Occupational exposure is primarily through inhalation pathway. Consumers

are exposed via use of a wide variety of household products such as fingernail polish, paint

thinner, caulking compounds, paint removers, and antifreeze.
3

1,2-Dichloroethylene (cis-, trans-, and mixed isomers)

The general U.S. population is exposed to this chemical via the inhalation of

contaminated ambient air and from ingestion of water from contaminated groundwater sources. 

Potentially high exposures are possible to those living near production/processing facilities,

municipal wastewater sites, hazardous waste sites, and municipal landfills. The National

Institute for Occupational Safety and Health (NIOSH) estimates that a small number of workers

(about 275) are potentially exposed occupationally via an inhalation or dermal pathway to one or

both of the isomers. No data are available for consumer exposure.

1,1,1,2-Tetrachloroethane

The general U.S. population is exposed to this compound thorough the inhalation of

ambient air. No data are available for occupational exposures. Consumers are possibly exposed

through their use of paints and varnishes, but confirmatory data are not available.

1,1-Dichloroethane

The general U.S. population is exposed to this chemical via the inhalation of ambient air

and the ingestion of contaminated drinking water. Higher exposures may exist for persons living

near industrial and hazardous waste sites. Occupational exposure occurs primarily via inhalation

during manufacturing processes using 1,1,-dichloroethane as a chemical intermediate, solvent,

and component of fumigant formulations. No data are available for consumer exposure.

Chloral

The general U.S. population may be exposed to chloral from drinking chlorinated water

and from pharmaceutical use. Some occupational exposure may result from chloral's production

and manufacture. No data are available for consumer exposure.

Chloral hydrate

The general U.S. population may be exposed to chloral hydrate from drinking chlorinated

water and from pharmaceutical use. No data are available for consumer exposure.

Monochloroacetic acid

No data are available for general U.S. population, occupational, and consumer exposure.

Dichloroacetic acid

The general U.S. population is exposed to this compound to this chemical via ingestion of

chlorinated drinking water and chlorinated water in swimming pools. No data are available for

occupational and consumer exposure.
4

Trichloroacetic acid

The general U.S. population is exposed to this chemical via the ingestion of contaminated

drinking water and foods. Occupational exposure may occur during the production and use of

trichloroacetic acid as a pesticide. No data are available for consumer exposure.

Dichloro-Vinyl Cysteine

There are no data for this chemical.
5

Table A-1. Summary of Potential Exposure Pathways and Potentially Exposed Populati

Chemical

Potential Exposure Pathway Potentially Exposed Population

Populations with Potentially High E

Inhalation Ingestion Dermal General Occupational Consumer 

TCE a b

~401,000 U.S.employees (1981-83survey)

Likely from use ofconsumer products thatcontain TCE.

People living near waste sites, in urindustrial areas with populations livmilitary bases, and with occupationpopulations who are continuously eto elevated levels. Exposure to the cpopulation is possible from use of cproducts. Products that generally cTCE include (paint removers, adhesetc.). Short-term exposure to high linclude people using consumer prodcontaining TCE with inadequateventilation. TCE has been detected breast milk, so exposure to nursing may occur.

PCE a b

~450,000 workers inthe dry-cleaningindustry; 688,110other employees(1981-83 survey)

Many consumerproducts such as spotremovers, inks, fabricfinishes have beenfound to contain PCE.

Persons working in dry cleaning indand metal degreasing most heavily people living with workers in the drcleaning industries; other populatiomay have elevated exposures includliving near hazardous waste facilitiepeople using products containing Pareas with inadequate ventilation. Pbeen detected in breast milk, so expnursing infants may occur.

1,1,1-Trichloroethane a

~2.5 x 106 workers

(1981-83 survey). Subcategoriesinclude nurses,maids, janitors,electricians,electronics workers,and apparel industry.

Consumer productssuch as paints, paintthinners, caulkingcompounds, fingernailpolish, paint removers,and food packagingadhesives have beenreported to contain1,1,1-trichloroethane

elevated exposures may occur topopulations in occupational categoras degreasing operations.

1,2-Dichloroethylene(cis-, trans-, andmixed isomers)

a Occupational

exposure to ~275people (mixedisomers and cisisomer only; data notavailable for transisomer)

Reported uses are in themanufacture ofpharmaceuticals,artificial pearls, and inthe extraction of oil andfats from fish and meat. However, these data areold (1985) andconsumer exposure datawere not available.

People living near waste sites andproduction/processing facilities and with occupational exposure.
Table A-1. Summary of Potential Exposure Pathways and Potentially Exposed Populations (c

Chemical

Potential Exposure Pathway Potentially Exposed Population

Populations with Potentially High E

Inhalation Ingestion Dermal General Occupational Consumer 

6

1,1,2,2-Tetrachloroethane

a

--c -- Probably exposed

through inhalation ofcontaminatedambient air

Reported use isprimarily a feed stockin the production ofsolvent. It is not knownif this is a closedproduction process.

Reported uses are in the manufactupaints and varnishes. It is not knowuse is current or if the products areconsumer or industrial products.

1,1-Dichloroethane -- Estimated at 715-

1,957 workers inearly 1980s. Exposure primarilyfrom use of chemicalas intermediate andsolvent inmanufacturingprocesses

NA Persons living near industrial and h

waste sites.

Chloral and ChloralHydrate

-- -- Approximately 2,757

employees (1981-83survey - chloral only)

NA NA 

MonochloroaciticAcid

NA c NA NA NA NA NA

Dichloroacetic Acid Approximately 1,592

employees (1981-83survey)

NA NA 

Trichloroacetic Acid -- Estimated employees

exposed is 35,124(1981-83 survey)

NA NA 

Dichloro-vinylCysteine

NA NA NA NA NA NA NA 
Table A-1. Summary of Potential Exposure Pathways and Potentially Exposed Populations (c

7

NA = Information not available.

 = Possible exposure pathway.

a Believed to be most prominent route of exposure, according to available data.b Population with the greatest chance of elevated exposure (for longer periods of time).c Probable exposure pathway, but not confirmed.
8

Table A-2. Preliminary Dose Estimates of TCE and Related Chemicals

Chemical Population Media

Range of Estimated Adult

Exposures

 (ug/day)

Range of Adult Doses 

(mg/kg/day) Data Sources

Trichloroethylene General Air 11 -- 33 1.57E-04 -- 4.71E-04 ATSDR (1997a)

General Water 2 -- 20 2.86E-05 -- 2.86E-04 ATSDR (1997a)

Occupational Air 2,232 -- 9,489 3.19E-02 -- 1.36E-01 ATSDR (1997a)

Tetrachloroethylene (PERC) General Air 80 -- 200 1.14E-03 -- 2.86E-03 ATSDR (1997b)

General Water 0.1 -- 0.2 1.43E-06 -- 2.86E-06 ATSDR (1997b)

Occupational Air 5,897 -- 219,685 8.43E-02 -- 3.14 ATSDR (1997b)

1,1,1-Trichloroethane General Air 10.8 -- 108 1.54E-04 -- 1.54E-03 ATSDR (1995)

General Water 0.38 -- 4.2 5.5E-06 -- 6.00E-05 ATSDR (1995)

1,2-Dichloroethylene General Air 1 -- 6 1.43E-05 -- 8.57E-05 ATSDR (1996a)

General Water 2.2 3.14E -05 ATSDR (1996a)

Cis-1,2-Dichloroethylene General Air 5.4 7.71E -05 HSDB (1996)

General Water 0.5 -- 5.4 7.14E-06 -- 7.71E-05 HSDB (1996)

1,1,1,2-Tetrachloroethane General Air 142 2.03E -03 HSDB (1996)

1,1-Dichloroethane General Air 4 5.71E -05 ATSDR (1990)

General Water 2.47 -- 469.38 3.53E-05 -- 6.71E-03 ATSDR (1990)

Chloral General Water 0.02 -- 36.4 2.86E-07 -- 5.20E-04 HSDB (1996)

Monochloroacetic Acid General Water 2 -- 2.4 2.86E-05 -- 3.43E-05 USEPA (1994)

Dichloroacetic Acid General Water 10 -- 266 1.43E-04 -- 3.80E-03 IARC (1995)

Trichloroacetic Acid General Water 8.56 -- 322 1.22E-03 -- 4.60E-03 IARC (1995)
9

Table A-3. Summary of U.S. Production Data

Chemical

U.S. Production Data (kilograms)

Production (yr) Import (yr) Export (yr)

TCE 1.17 x 105

 (1981)

7.72 x 107 (1985)

1.45 x 108

 (1991)

1.98 x 107

 (1985) 1.06 x 107 (1985)

PCE 3.08 x 108

 (1985)

1.84 x 108

 (1986)

2.14 x 108 (1989)

1.60 x 108

 (1990)

1.08 x 108 (1991)

1.12 x 108 (1992)

1.23 x 108

 (1993)

1.70 x 107

 (1982)

6.36 x 107

 (1985)

8.3 x 104 (1986)

2.47 x 107

 (1983)

9.84 x 106

 (1985)

1,1,1-Trichloroethane 3.64 x 108

 (1990)

3.13 x 108 (1992)

4.54 x 104 (1981)

5.99 x 106 (1992)

9.08 x 104 (1993)

5.20 x 107

 (1990)

7.39 x 107 (1991)

6.34 x 107 (1992)

3.44 x 107

 (1993)

1,2-Dichloroethylene NA NA NA

Cis-1,2-Dichloroethylene 5.0 x 105

 (1977 - captive

production)

NA NA

Trans-1,2-Dichloroethylene NA NA NA

1,1,2,2-Tetrachloroethane NA NA NA

1,1-Dichloroethane NA NA NA

Chloral 2.83 x 107

 (1969)

2.27 x 107

 (1975)

1.02 x 105

 (1984) Negligible (1972; 1975)

Chloral Hydrate 1.14 x 107

 (1972 - anhydrous)

5.9 x 105

 (1975)

2.83 x 104

 (1972)

4.8 x 104

 (1975)

5.41 x 103

 (1984)

NA

Monochloroacetic Acid 3.5 x 107

 (1978)

>6.81 x 103

 (1982)

1.25 x 107

 (1978)

1.35 x 107

 (1982)

Negligible (1993)

Dichloroacetic Acid NA NA NA

Trichloroacetic Acid >3.6 x 103

 (1975)

>2.27 x 103

 (1976)

3.67 x 106

 (1984) 8.6 x 106 (1984)

Dichloro-vinyl Cysteine NA NA NA

NA = Not available.

Sources: HSDB, 1996; IARC, 1995.
10

INTRODUCTION

This report summarizes currently available exposure related information about TCE, its

metabolites, and other parent compounds that produce these same metabolites. Thus, this

assessment is a departure from typical exposure assessment of a chemical in that it considers

exposure to metabolites as well as parent compounds. Exposure information is summarized for

the following 14 compounds:

C Trichloroethylene;

C The primary metabolites of trichloroethylene: dichloro-vinyl cysteine, chloral,

chloral hydrate, trichloroacetic acid, dichloroacetic acid, monochloroacetic acid;

and

C The primary parent compounds which produce the same metabolites as

trichloroethylene: tetrachloroethylene, methyl chloroform, 1,1,1,2-

tetrachloroethane, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,2-

dichloroethylene, and 1,1-dichloroethane.

Not all possible metabolites of trichloroethylene and related parent compounds were

included in the scope of this document. The metabolites were limited to human metabolites that

are produced in the largest quantities and are most important in producing toxic effects. The

parent compounds were limited to those to which humans are most commonly exposed. The two

parent compounds of most importance were trichloroethylene and tetrachloroethylene, and the

two metabolites of most importance were trichloroacetic acid and dichloroacetic acid. These

four compounds were given the highest priority in terms of the level of effort spent in developing

this document.

Figure A-1 shows the parent-metabolite relationships between the compounds covered in

this document. The actual pathways of metabolism are much more complicated than shown here

and it should be understood that this diagram is intended only to give the reader a general

understanding of which parent compounds lead to which metabolites. The key limitations of this

diagram are summarized below:

C The diagram does not include all metabolites of trichloroethylene.

C The diagram does not include all potential parent compounds which could lead to

the listed metabolites. For example, acetic acids are common metabolites of many

compounds.

C The diagram does not show the intricacies of the metabolic pathways. For

example, interconversion can occur between some metabolites, many reactions

include intermediate steps and the reactions can be affected by enterohepatic

circulation and renal reabsorption.
Trichloroethylene 

(TCE)

Methyl C

1,1,1,2-Tetra

1,2-Dichlo

Tetrachlo

1,1-Dichlo

Trichloroethanol

Dichlorovinylcysteine

Monochloroacetic 

Acid

Dichloroacetic 

Acid

Chloral Hydrate 

Chloral

Trichloroacetic 

Acid

11

Figure A-1. Trichloroethylene, Related Parent Compounds, and Their Metabol
12

C The diagram does not represent quantitative relationships (i.e., some metabolites

are produced in much higher quantities than others and concepts such as half-life

and reaction kinetics are not represented).

This report has drawn heavily on information presented in the 1995 International Agency

for Research on Cancer publication (IARC 1995) and profiles on several chemicals from the

Agency for Toxic Substances and Disease Registry (ATSDR 1990, 1995, 1996a, 1997a,b).

Additional informational sources include electronic literature searches, on-line searches of the

Hazardous Substances Data Base, and data retrievals from the U.S. EPA Toxic Release Inventory

(TRI).

This report is organized in three sections. Section A includes this introduction and

summary of the results. Section B summarizes readily available information on the physicalchemical properties, production and use, potential for human exposure, and exposure and

population estimates for TCE and the other parent compounds. The final section, Section C,

summarizes the same exposure-related information for the TCE metabolites.

There are a number of limitations and uncertainties in this report that result primarily

from the lack of information and that much of the data are not current, although found in current

publications. It should be noted that monitored chemical levels presented in this report are

primarily for the United States. Information on most metabolites is relatively sparse and is

completely lacking for one chemical.

Research is needed to gather data, especially to confirm current production, use, release,

and disposal practices and study fate of the chemicals in certain media (especially groundwater

and soils). Reliable, current monitoring data for levels in environmental media are needed to

assess human exposures. Most of the monitoring data reported are old and based on occupational

studies data. Additionally, the monitoring data for humans are basically for levels in blood and

urine only. Research is needed to address monitored levels of these chemicals in other human

tissues for the general population and populations around hazardous waste sites as well.
13

SECTION B. PARENT COMPOUNDS

1.0 TRICHLOROETHYLENE

1.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

1.1.1 Nomenclature

CAS No.: 79-01-6

Synonyms: 1-chloro-2,2-dichloroethylene; ethene, trichloro-; acetylene

trichloride, TCE.

Trade Names: Chlorylea, Chlorylen, CirCosolv, Crawhaspol, Dow-Tri,

Dukeron, Per-A-Clor, Triad, Trial, TRI-Plus M, Vitran, Perm-AChlor (and others).

1.1.2 Formula and Molecular Weight

Molecular Formula: C2HCl3

Molecular Weight: 131.40

1.1.3 Chemical and Physical Properties

Description: Clear, colorless, or blue mobile liquid (Remington’s Pharm. Sci.,

16th Ed., 1980); chloroform-like odor (Weast, 1986-87).

Boiling Point: 87° C (Weast, 1987-1988).

Melting Point: -73° C (Weast, 1987-1988).

Density: 1.4649 @ 20° C/4° C (Merck Index, 11th Ed., 1989).

Spectroscopy Data: Sadtler Ref. Number: 185 (IR, Prism); Max. Absorption: less

than 200 nm (vapor) (Weast, 1979); Index of refraction: 1.4773

@ 20° C/D (Weast, 1986-87); IR: 62 (Weast, 1979).

Solubility: 1,100 mg/l water at 25° C (Verschueren, 1983).

Volatility: Vapor Pressure: 19.9 mm Hg @ 0° C; 57.8 mm Hg @ 20° C

(NRC, 1981).
14

Vapor Density: 4.53 (air = 1) (Merck Index, 1989).

Stability: Relatively stable in air (Browning, Tox Metab Indus Solv, 1965);

Unstable in light and moisture (Osal, 1980).

Reactivity: Incompatible with strong caustics and alkalis; chemically-active

metals such as barium, lithium, sodium, magnesium, titanium,

and beryllium (NIOSH Pocket Guide Chemical Hazards, 1994).

Octanol/Water

Partition Coefficient: log Kow = 2.29 (Hansch, 1979).

1.1.4 Technical Products and Impurities

Trichloroethylene is available in the USA in high-purity, electronic USP, technical, metal

degreasing, and extraction grades (IARC Monographs, 1972-present, V20, 1979). Commonly

used stabilizers found in commercial trichloroethylene products include: pentanol-2

triethanolamine, 2,2,4-trimethylpentene-1, and iso-butanol. Tetrachloroethane is a contaminant

in commercial trichloroethylene (ARENA, 1986). Impurities found in commercial

trichloroethylene products include: carbon tetrachloride, chloroform, 1,1,1,2-trichloroethane, and

benzene (WHO, 1985).

1.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC

(1995).

1.2.1 Production

U.S. Production: (1981) 1.17 x 108

 g (USITC, 1981); (1985) 7.72 x 1010 g

estimated (USITC, 1985); (1991) 1.45 x 1011 g (SRI. Directory

Chem. Producers-USA, 1992).

Import Volume: (1985) 1.98 x 1010 g (Bureau of the Census, U.S. Imports, 1985).

Export Volume (1985) 1.06 x 1010 g (Bureau of the Census, U.S. Exports, 1985).

1.2.2 Uses

The major use of trichloroethylene is degreasing (IARC, 1995). About 85 percent of the

TCE produced is used in metal cleaning. Other uses include the manufacture of organic

chemicals; as a solvent in adhesives and paint-stripping formulations, paints, lacquers, varnishes;

heat transfer medium-EG; in case hardening of metals; a solvent base for metal phosphatizing

systems; and solvent in characterization test for asphalt (SRI). It was also used earlier as an

extractant for spice oleoresins, natural fats and oils, hops and decaffeination of coffee (IARC,
15

1995), and a carrier solvent for the active ingredients of insecticides and fungicides, and for

spotting fluids (WHO; Environ. Health Criteria, 1985). TCE has been replaced in the dry

cleaning industry with tetrachloroethylene (ATSDR, 1997a). Its use as a fumigant and as an

extractant for decaffeinating coffee has been discontinued in the U.S. (ATSDR, 1997a). Its use

in cosmetics and drug products was also discontinued (IARC, 1995).

1.2.3 Disposal

Generators of waste (equal to or greater than 100 kg/month) containing this contaminant

(EPA hazardous waste numbers U228, D040, and F002) must conform with U.S. EPA

regulations in storage, transportation, treatment, and disposal of waste (40 CFR 240-280, 7/1/91). 

Incineration is a method of disposal, preferably after mixing with another combustible fuel. Care

must be exercised to assure complete combustion to prevent the formation of phosgene. An acid

scrubber is necessary to remove the halo acids produced. An alternative to disposal for

trichloroethylene is recovery and recycling (Sittig, 1985. Handbook Toxic Hazardous Chemicals

and Carcinogens). This compound should be susceptible to removal from wastewater by air

stripping (U.S. EPA, 1980). 

1.3 POTENTIAL FOR HUMAN EXPOSURE

1.3.1 Natural Occurrence

The natural occurrence of trichloroethylene has been reported in one red microalga and in

temperate, subtropical and tropical algae (IARC, 1995).

1.3.2 Occupational Exposure

Occupational exposure to TCE of workers in industries using TCE may result from

inhalation of vapors or through dermal contact with TCE from spills.

1.3.3 Environmental

1.3.3.1 Environmental Releases

Total Toxic Release Inventory (EPA, 1996) releases for years 1987 to 1994 are shown in

Table 1-1. The receiving media are air, water, land, and for underground injection, POTW

(Public Owned Treatment Works) transfer and other transfers. These releases are reported from

manufacturing and processing facilities. Only certain facilities are required to report.
16

Table 1-1. Annual Releases of Trichloroethylene in the United States (lbs)

Year

Number of

reporting

facilities

Fugitive air

releases

Stack air

releases

Surface

water

releases

Underground

injection

Land

disposal

POTW

transfer

Other

transfers Total

1987 959 25,978,879 29,436,952 30,104 18,720 56,733 130,178 11,689,590 67,341,156

1988 951 26,168,126 29,759,510 13,801 390 21,186 85,652 6,509,867 62,558,532

1989 899 22,629,351 27,054,328 15,849 390 8,686 31,519 4,962,054 54,702,177

1990 807 19,030,377 20,900,640 14,285 805 12,554 11,949 3,879,599 43,850,209

1991 724 17,078,485 18,860,997 12,784 800 62,991 73,195 10,625,967 46,715,219

1992 681 15,585,757 14,866,100 8,606 466 20,726 70,149 9,807,719 40,359,523

1993 790 14,524,316 15,939,964 5,220 460 8,212 42,987 10,143,591 40,664,750

1994 783 14,788,788 15,083,085 1,671 288 4,417 50,325 12,307,585 42,236,159

Source: TRI 1996

Air: Most of the TCE used in the U.S. is released to the atmosphere primarily from

vapor degreasing operations by evaporation (ATSDR, 1997a). Releases to air also occur at

treatment and disposal facilities, water treatment facilities, and landfills (ATSDR, 1997a). TCE

has also been detected in stack emissions from the municipal and hazardous waste incineration

(ATSDR, 1997a). TCE has been detected in the air throughout the United States. Industrial

releases to the environment in the U.S. ranged from 55.6 million pounds in 1987 down to 29.9

million pounds in 1994 (TRI, 1996).

Water: TCE has been reported in rainwater, surface waters, groundwater, drinking

water, and seawater (IARC, 1995). TCE is released to the aquatic systems from industrial

discharges of wastewater streams (ATSDR, 1997a). It has been reported that TCE in landfill

leachate can contaminate groundwater; TCE has been reported to be one of the most frequent

contaminants of groundwater (ATSDR, 1997a).

Other Media: TCE has been reported in marine sediments, marine invertebrates, marine

mammals, foods, mother’s milk, and human urine and blood (IARC, 1995) (HSDB, 1996).

1.3.3.2. Monitored Environmental Media Levels

Air: TCE has been detected in the air throughout the United States. According to ATSDR

(1997a), atmospheric levels are highest in areas concentrated with industry and population, and

lower in remote and rural regions. Air levels of TCE are highly variable (fluctuate widely over

relatively short periods of time), depending on strength of emission sources, variation of wind

direction and velocity and other meteorological factors, rain scavenging, and

photodecomposition. Levels of TCE measured in the ambient air at a variety of locations in the

U.S. are shown in Table 1-2. These data were derived from studies conducted in the late 1970's

and early 1980's.
17

Table 1-2. Concentrations of Trichloroethylene in Ambient Air

Area Year

Concentration (μg/m3

)

*

Mean Range

Rural

Whiteface Mountain, NY

Badger Pass, CA

Reese River, NV

Jetmar, KS

1974

1977

1977

1978

0.5

0.06

0.06

0.07

<0.3-1.9

0.005-0.09

0.005-0.09

0.04-0.11

Urban and Suburban

New Jersey

New York City, NY

Los Angeles, CA

Lake Charles, LA

Phoenix, AZ

Denver, CO

St. Louis, MO

Portland, OR

Philadelphia, PA

1973-79

1974

1976

1976-78

1979

1980

1980

1984

1983-84

9.1

3.8

1.7

8.6

2.6

1.07

0.6

1.5

1.9

ND-97

0.6-5.9

0.14-9.5

0.4-11.3

0.06-16.7

0.15-2.2

0.1-1.3

0.6-3.9

1.6-2.1

 Source: IARC, 1995. * 1 μg/m3

=0.17 ppb

 Other ambient air measurement data for TCE were obtained from the Aerometric

Information Retrieval System (AIRS) using the AIRS Website: http://www.epa.gov/airsdata/. 

(U.S. EPA, 1999a). These data were collected from a variety of sources including State and local

environmental agencies and cover the years 1985 to 1998. They represent about 1,200

measurements from 25 states. The most recent data (1998) come from 115 monitors located in

14 states. The 1998 air levels in :g/m3 across all 115 monitors can be summarized as follows: 

range = 0.01 to 3.9; mean = 0.88, 50th percentile = 0.32 and 90th percentile = 1.76. Table 1-3

summarizes the data by year, showing the average and number of samples. Relatively few

samples were collected in 1985 and 1986, but each year after 1986 is represented by at least 50

samples. The data suggest a general downward trend from about 1.5 :g/m3 in the late 1980s to

0.8 :g/m3 in the late 1990s. Table 1-4 shows the monitoring data organized by land setting

(rural, suburban, or urban) and land use (agricultural, commercial, forest, industrial, mobile, and

residential). Urban air levels are about three times higher than rural areas. Among the land use

categories, TCE levels are highest in commercial/industrial areas and lowest in forest areas. 

TCE ambient air concentrations in 1990 were modeled for all census tracts of the

continental United States as part of the U.S. EPA Cumulative Exposure Project (CEP, see

www.epa.gov/cumulativeexposure/air/air.htm). (U.S. EPA, 1999b). A variety of sources were

used to obtain emissions data and the air modeling was done using a Gausian dispersion model.

Table 1-5 shows the distribution of modeled TCE ambient air concentrations across the

continental United States. The modeling suggests that 97% of the census tracts have TCE

concentrations ranging from 0 to 1.5 :g/m3

. The average level was estimated as 0.37 :g/m3 and

the maximum as 32 :g/m3. The averages and percentiles are better interpreted as populationweighted values than spatial averages because all census tracts have roughly equal populations,

but are more variable in geographic area. Figure 1-1 is a map of the CEP-modeled TCE air

concentrations in New Jersey. The average across all population tracts in the state is 0.5 :g/m3

.

The map indicates, however, that the vast majority of the state, on an area basis, has levels under 
Table 1-3. Mean TCE Air Levels Across Monitors by Year*

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 

Mean Concentration(:g/m3)

1.4 1.39 1.68 4.87 1.69 1.84 2.86 1.37 1.12 0.95 0.78 0.

n 11 21 53 57 96 59 70 76 84 89 146 15

Table 1-4. Mean TCE Air Levels Across Monitors by Land Setting and Use (1985 to 1998)*

Rural Suburban Urban Agricultural Commercial Forest Industrial 

Mean Concentration(:g/m3

)

0.42 1.26 1.61 1.08 1.84 0.1 1.54 1

n 93 500 558 31 430 17 186 3

Table 1-5. Modeled TCE Air Concentrations in Continental U.S. for 1990*

25th Percentile 50th Percentile 75th Percentile 95th Percentile Maximum Overall Me

Concentration(:g/m3

)

0.13 0.24 0.45 1.1 32 0.37 

 *1 ppb = 5.36 :g/m3

.

18
19

TCE (microgram/cub meter)

0.085 - 0.501

0.501 - 1.2

1.2 - 3.21

3.21 - 12.025

12.025 - 31.584

State Boundary, NJ

Inset

Figure 1-1. Modeled TCE Levels in Air from Cumulative Exposure Project by Census Tract,

New Jersey (:g/m3

)
20

0.5 :g/m3

. Relatively high levels (generally 1 to 12 :g/m3) were estimated for the densely

populated areas around Camden and Newark - Paterson. The highest levels (up to 30 :g/m3

)

were estimated for a few (presumably industrial) sectors within these areas. The CEP data

suggest that this pattern (i.e., generally low TCE levels in rural areas, moderate levels in urban

areas, and highest levels in small commercial/industrial sectors) is common across most states. 

The monitoring data, as discussed earlier, also suggest that this is the general pattern across the

country. 

These modeled values should be interpreted with caution. Clearly they are not as reliable

as measured values for specific locations. As discussed earlier, the AIRS data shows an average

for 1990 across 59 monitoring stations of 1.84 :g/m3. This is much higher than the national

average from CEP of 0.37 :g/m3. An important difference, though, is that the CEP estimate

represents all areas of the continental United States, whereas the 1990 AIRS data for TCE

represent only 59 monitors located in 8 states. CEP compared modeled estimates with measured

values in the same locations and found that for most chemicals, agreement was usually within a

factor of three, with underestimates being more common than overestimates. More variability,

however, was found in the model-monitor comparisons for TCE than for other HAPs (hazardous 

air pollutants). In addition, the tendency for underestimation in the model observed for other

HAPs was not seen for TCE. The TCE model-monitor comparisons can be summarized as

follows: model-monitor comparisons were made at 57 monitoring sites, the median of the modelmonitor ratios was 0.76, arithmetic mean ratio = 2.33, geometric mean ratio = 1.02, 53% of ratios

were less than 1.0, 51% were within a factor of 3 (i.e. within the range of 0.33 to 3.0), 19% were

less than 0.33 and 30% were greater than 3.0.

Water: According to IARC (1995), the reported median concentrations of TCE in 1983-

84 were 0.5 μg/l in industrial effluents and 0.1 μg/l in ambient water. ATSDR (1997a) has

reported that TCE is the most frequently reported organic contaminant in groundwater and the

one present in the highest concentration in a summary of ground water analyses reported in 1982. 

It has been estimated that between 9 percent and 34 percent of the drinking water supply sources

tested in the U.S. may have some trichloroethylene contamination. This estimate is based on

available Federal and State surveys (ATSDR, 1997a). Results from an analysis of the EPA

STORET Data Base (1980-1982) showed that TCE was detected in 28 percent of 9,295 surface

water reporting stations nationwide (ATSDR, 1997a). Levels of TCE found in rainwater,

groundwater, and drinking water are shown in Table 1-6. 

More recently, the U.S. EPA Office of Ground Water and Drinking Water reported that

most water supplies are in compliance with the maximum contaminant level [maximum

contaminant level (MCL), 5 :g/L] and that only 407 samples out of many thousands taken from

community and other water supplies throughout the country over the past 11 years (1987-1997)

have exceeded the MCL limit for TCE (U.S. EPA, 1998). 

TCE concentrations in ground water have been measured extensively in California. The

data were derived from a survey of large water utilities (i.e., utilities with more than 200 service

connections). The survey was conducted by the California Department of Health Services (DHS,

1986). From January 1984 through December 1985, wells in 819 water systems were sampled for

organic chemical contamination. The water systems use a total of 5,550 wells, 2,947 of which

were sampled. TCE was found in 187 wells at concentrations up to 440 :g/L, with a median 
21

Table 1-6. Concentrations of Trichloroethylene in Water

Water Type Location Year Mean Median Range Number of Samples Ref.

Industrial

Effluent

U.S. 83 0.5 NR IARC, 1995

Surface Waters U.S. 83 0.1 NR IARC, 1995

Rainwater Portland, OR 84 0.006 0.002-0.02 NR Ligocki, et.al , 1985

Groundwater MN

NJ

NY

PA

MA

AZ

83

76

80

80

76

0.2-144

<1530

<3800

<27300

<900

8.9-29

NR

NR

NR

NR

NR

NR

Sabel, et.al, 1984

Burmaster, et. al. ‘82

Burmaster, et. al. ‘82

Burmaster, et. al. ‘82

Burmaster, et. al. ‘82

IARC, 1995

Drinking water U.S.

U.S

U.S.

MA

NJ

CA

CA

NC

ND

76

77

78

84

84-

85

84

84

84

23.4

66

5

5

0.2 - 49

0 - 53

0.5 - 210

max. 267

max. 67

8-12

1130

486

486

48

48

IARC, 1995

IARC, 1995

IARC, 1995

IARC, 1995

Cohn, et.al., 1994

EPA, 1987

EPA, 1987

EPA, 1987

EPA, 1987

NR - Not Reported

concentration of 3.0 :g/L. Generally, the most contaminated wells and the wells with the highest

concentrations were found in the heavily urbanized areas of the state. Los Angeles County

registered the greatest number of contaminated wells (149).

Other Media: Levels of TCE were found in the sediment and marine animal tissue

collected in 1980-81 near the discharge zone of a Los Angeles County waste treatment plant. 

Concentrations were 17 μg/l in the effluent, <0.5 μg/kg in dry weight in sediment, and 0.3-7

μg/kg wet weight in various marine animal tissue (IARC, 1995). TCE has also been found in

foods in the U.S. and the United Kingdom. The average concentrations of TCE in food in the

U.S. were the following (IARC, 1995):

C 0.9 μg/kg in grain-based foods;

C 1.8 μg/kg in table-ready foods;

C 73.6 μg/kg in butter and margarine;

C 0.5 μg/kg in peanut butter;

C 3.0 μg/kg in ready-to-eat cereals;

C 1.3 μg/kg in highly processed foods; and

C 3.8 μg/kg in cheese products.

Biological Monitoring: Biological monitoring studies have detected TCE in human

blood and urine in the U.S. and other countries such as Croatia, China, Switzerland, and

Germany (IARC, 1995). Concentrations of TCE in persons exposed through occupational

degreasing operations were most likely to have detectable levels (IARC, 1995). In 1982, eight of
22

eight human breastmilk samples from four U.S. urban areas had detectable levels of TCE. The

levels of TCE detected, however, were not specified (HSDB, 1996; ATSDR, 1997a).

The Third National Health and Nutrition Examination Survey (NHANES III) examined

TCE concentrations in blood in 677 non-occupationally exposed individuals drawn from the

general U.S. population who were selected on the basis of age, race, gender and region of

residence (IARC, 1995 and Ashley et al., 1994). The samples were collected during 1988 to

1994. TCE levels in whole blood were below the detection limit of 0.01 :g/l for about 90% of

the people sampled (Table 1-7). Assuming that nondetects equal half of the detection limit, the

mean concentration was about 0.017 μg/l.

1.3.3.3 Environmental Fate and Transport

1.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of trichloroethylene released to

surface soils is volatilization. Because of its moderate to high mobility in soils, trichloroethylene

introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater. 

The relatively frequent detection of trichloroethylene in groundwater confirms the mobility of

trichloroethylene. Biodegradation in soil and groundwater may occur at a relatively slow rate

(half-lives on the order of months to years) (Howard et al., 1991).

Fate in the Atmosphere: In the atmosphere, trichloroethylene is expected to be present

primarily in the vapor phase rather than sorbed to particulates because of its high vapor pressure. 

Some removal by scavenging during wet precipitation is expected because of the moderate

solubility of trichloroethylene in water (1.1 g/L). The major degradation process affecting vapor

phase trichloroethylene is photo-oxidation by hydroxyl radicals (half-life on the order of 1 to 11

days) (HSDB, 1996).

Fate in Aquatic Environments: The dominant fate of trichloroethylene released to

surface waters is volatilization (predicted half-life of minutes to hours). Bioconcentration,

biodegradation, and sorption to sediments and suspended solids are not thought to be significant

(HSDB, 1996).

Table 1-7. TCE Levels in Whole Blood by Population Percentile*

Percentiles 10 20 30 40 50 60 70 80 90

Concentration

(:g/l)

0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.012

* Nondetects assumed equal to half the detection limit (0.01 :g/L).

Data from IARC (IARC, 1995) and Ashley (Ashley, 1994)
23

1.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: Kocs ranging from 30 to 150 have reported in studies with

various soil types indicate that trichloroethylene should exhibit moderate to high mobility in soil. 

The mobility of trichloroethylene in soil has been confirmed in soil column studies and river

bank infiltration studies (HSDB, 1996).

 

Volatilization: The dominant removal mechanism for trichloroethylene in surface waters

is volatilization. The half-life will depend on wind and mixing conditions and is estimated to

range from several minutes to hours in rivers, lakes, and ponds based on laboratory experiments

and field studies. Because of its high vapor pressure (73 torr at 25 degrees C) and relatively low

soil adsorption coefficient (30 to 150), trichloroethylene is expected to volatilize from soil

surfaces and also from suspended particulate matter in the atmosphere (HSDB, 1996).

Bioconcentration: Bioconcentration factors of 17 to 39 have been reported in bluegill

sunfish and rainbow trout. Marine monitoring data suggest BCFs of 2 to 25. Therefore,

bioconcentration in aquatic organisms should not be significant and there is little potential for

biomagnification in the food chain (HSDB, 1996).

1.3.3.3.3 Transformation and Degradation Processes

Biodegradation: Based on limited acclimated soil screening test data, trichloroethylene

undergoes aerobic biodegradation at a very slow rate with a half-life estimated at 6 months to a

year. Slow degradation under anaerobic conditions is expected (half-life of months to years)

based on the results of limited anaerobic sediment studies (Howard et al., 1991).

Photodegradation: Photolysis in the atmosphere or in aquatic environments is expected

to proceed very slowly, if at all. Trichloroethylene does not absorb UV light at wavelengths of

less than 290 nm and thus will not directly photolyze. Based on measured rate data for the vapor

phase photo-oxidation reaction with hydroxyl radicals, the estimated half-life of trichloroethylene

in the atmosphere is on the order of 1 to 11 days with production of phosgene, dichloroacetyl

chloride, and formyl chloride. Under smog conditions, degradation is more rapid (half-life on the

order of hours) (HSDB, 1996; Howard et al., 1991).

Hydrolysis: Trichloroethylene is not hydrolyzed under normal environmental conditions. 

However, slow photo-oxidation in water (half-life of 10.7 months) has been reported (HSDB,

1996; Howard et al., 1991)

1.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

1.4.1 General U.S. Population

Because of the pervasiveness of TCE in the environment, most people are exposed to it

through ingestion of drinking water, inhalation of ambient air, or ingestion of food (ATSDR,

1995a). Contamination of drinking water with TCE varies according to location and with the

drinking water source (whether source is surface water or groundwater). TCE readily volatilizes

from water and inhalation of indoor air may be a major route of exposure in homes with
24

contaminated water supply (ATSDR, 1997a). Available data indicate that for most people,

dermal exposure is not an important route of exposure (ATSDR, 1997a).

The 1998 AIRS monitoring data indicate a mean outdoor air level of 0.88 :g/m3. Using

this value and an inhalation rate of 20 m3 air/day yields an exposure estimate of 18 :g/day. This

is consistent with ATSDR (ATSDR, 1997a), which reported an average daily air intake for the

general population of 11 to 33 :g/day The California survey of large water utilities in 1984

found a median concentration of 3.0 :g/L (DHS, 1986). Using this value and a 2 L/day water

consumption rate yields an estimate of 6 :g/day. This is consistent with ATSDR (ATSDR,

1997a) which reported an average daily water intake for the general population of 2 to 20 :g/day.

The use of ambient air data to estimate inhalation exposure does not account for possible

differences between contaminant levels in indoor vs. outdoor air. TCE readily volatilizes from

water and indoor inhalation exposure may be comparable or greater than ingestion exposures in

homes where the water supply contains TCE (ATSDR, 1997a, Andelman, et.al., 1985, Giardino,

et.al., 1992, Andelman, et.al., 1986a, Andelman, et.al., 1986b). For example, in two homes using

well water with TCE levels averaging 22 to 128 :g/L, the TCE levels in bathroom air ranged

from <0.5 to 40 mg/m3 when the shower was run less than 30 minutes (Andelman et al., 1985). 

In one study, the transfer of TCE from shower water to air had a mean efficiency of 61%

(independent of water temperature); it was concluded that a 10-minute shower in TCEcontaminated water could result in a daily inhalation exposure comparable to that expected from

drinking TCE-contaminated tap water (ATSDR, 1997a). Indoor use of TCE containing products

can also contribute to exposures. Wallace et al. (Wallace, et.al., 1985) concluded that indoor air

contributes more to overall TCE exposure than outdoor air. This was based on monitoring of

expired breath of 190 people in New Jersey. This is also indicated in the TEAM (Total

Exposure Assessment Methodology) Study (U.S. EPA, 1987), which shows, for example, that

the ratio of the indoor to outdoor TCE concentration for Greensboro, NC was about 5:1. 

Accordingly, ambient air-based exposure estimates probably under represent total inhalation

exposures. 

TCE in bathing water can also cause dermal exposure. A modeling study has suggested

that a significant fraction of the total dose associated with exposure to volatile organics in

drinking water results from dermal absorption (Brown, et.al., 1984).

Pharmacokinetic modeling can be used to gain further understanding of general

population exposure. Clewell et al. (Clewell, et.al., 1995) developed a physiologically based

pharmacokinetic model for TCE that can be used to estimate the long-term average inhaled air

concentration that would result in a measured blood concentration, assuming no other TCE

exposure. The model can also estimate the long-term average ingested dose that would result in

a measured blood concentration, assuming no other TCE exposure. This dose can be converted

to a TCE water concentration assuming an ingestion rate such as 2 L/day. For each of these

exposure scenarios, the model also provides the corresponding concentrations of trichloroacetic

acid (TCA) and dichloroacetic acid (DCA) in blood and the amount of TCE metabolized per day. 

This model was applied to the range of TCE levels in blood as measured in NHANES III. Table

1-8 shows the resulting exposure estimates corresponding to the range of TCE blood levels. The

TCE environmental concentrations modeled from blood levels exceeded the range of measured

values for air and water: modeled mean concentration in drinking water was 59.5 :g/L

(measured range was trace to 50 :g/L) and the modeled mean air concentration was 4.2 :g/m3
25

(measured range was for 0.01 to 3.9 :g/m3) . This implies that neither inhalation nor water

ingestion dominate exposure; rather both contribute to the total exposure. Exposure estimates

derived from blood cannot distinguish among exposure routes and sources. It is generally

believed that TCE exposure occurs primarily via water consumption and air inhalation, but it is

impossible to use the blood data to directly estimate how much of the total exposure is

attributable to each. A wide range of combinations of exposures from air and water could have

produced the measured blood levels. As noted earlier, most water supplies have TCE levels

under the MCL of 5 :g/L. The modeling suggests that exposure at the MCL would correspond

to a very low blood level. This implies that the TCE exposure via the air and other nonwater

pathways may generally be more important than water ingestion. Table 1-8 provides the

modeled exposure estimates corresponding to a range of blood levels, and Table 1-9 shows a

comparison of measured and modeled TCE concentrations in air and drinking water.

1.4.1.1 Extent of General Population Exposure

Because of the pervasiveness of TCE in the environment, most people are likely to have

some exposure via one or more of the following pathways: ingestion of drinking water,

inhalation of ambient air, or ingestion of food (ATSDR, 1995a). As noted earlier, the NHANES

survey suggests that about 10% of the population has detectable levels of TCE in blood. The

exposures in these individuals may be higher than those in others in the general population as a

result of a number of factors. As discussed below, some occupations and the use of certain

consumer products can cause increased TCE exposure via inhalation. In addition, some members

of the general population may have increased TCE exposure via their drinking water. The extent

of TCE exposure via drinking water is difficult to estimate, but the following discussion provide

some perspective on this issue. 

Table 1-8. Modeled Exposure Estimates for TCE

Air concentration

(:g/m3

)

Ingested dose

(:g/kg-day)

Water concentration

(:g/L)

10th percentile blood level

(0.005:g/L)

1.25 0.5 17.5

90th percentile blood level

(0.012 :g/L)

3.0 1.2 42.0

Mean blood level (0.017

:g/L)

4.3 1.7 59.5

Table 1-9. Comparison of Measured and Modeled TCE Concentrations

Measured Range Modeled Mean

Air 0.0005 to 16 ug/m3 4.58 :g/m3

Drinking Water trace to 50 :g/L 59.5 :g/l
26

TCE is the most frequently reported organic contaminant in ground water (ATSDR,

1997a), 93% of the public water systems in the United States obtain water from groundwater

(U.S. EPA, 1995) and between 9% and 34% of the drinking water supply sources tested in the

United States may have some TCE contamination (ATSDR, 1997a). Although commonly

detected in water supplies, the levels are generally low since, as discussed earlier, MCL

violations for TCE in public water supplies are relatively rare for any extended period (U.S. EPA,

1998). Private wells, however, are often not closely monitored and if located near TCE

disposal/contamination sites where leaching occurs, may have undetected contamination levels.

About 10% of Americans (27 million people) obtain water from sources other than public water

systems, primarily private wells (U.S. EPA, 1995). TCE is a common contaminant at Superfund

sites. It has been identified in at least 861 sites of the 1,428 hazardous waste sites proposed for

inclusion on the EPA National Priorities List (NPL) (See Figure 1-2. ATSDR, 1997a). Studies

have shown that many people live near these sites: 41 million people live less than 4 miles from

one or more of the nation's NPL sites, and on average 3,325 people live within 1 mile of any

given NPL site (ATSDR, 1996b). Thus, although exact estimates cannot be made, many people

are probably exposed to TCE via drinking water from private wells. It is not known how often

such exposures would be above the MCL. 

Some members of the general population may have elevated TCE exposures. ATSDR

(ATSDR, 1997a) has reported that TCE exposures may be elevated for people living near waste

facilities where TCE may be released, residents of some urban or industrialized areas, people

exposed at work (discussed further below) and individuals using certain products (also discussed

further below). Because TCE has been detected in breast milk samples of the general population,

infants who ingest breast milk may be exposed. Also, since TCE can be present in soil, children

may be exposed through activities such as playing in or ingesting soil.

1.4.2 Occupational Exposure

Occupational exposure to TCE in the U.S. has been identified in various degreasing

operations, silk screening, taxidermy, and electronic cleaning (IARC, 1995). The major use of

trichloroethylene is for metal cleaning or degreasing (IARC, 1995). Degreasing is used to

remove oils, greases, waxes, tars, and moisture before galvanizing, electroplating, painting,

anodizing, and coating. The five primary industrial groups are: furniture and fixtures; electronic

and electric equipment; transport equipment; fabricated metal products; and miscellaneous

manufacturing industries (IARC, 1995). Additionally, TCE is used in the manufacture of

plastics, appliances, jewelry, plumbing fixtures, automobile, textiles, paper, and glass (IARC,

1995). NIOSH conducted a survey of various industries from 1981 to 1983 and estimated that

approximately 401,000 U.S. employees in 23,225 plants in the U.S. are potentially exposed to

TCE (IARC, 1995; ATSDR, 1997a). The majority of published worker exposure data are for

degreasing operations; time weighted average (TWA) concentrations from personal monitoring

ranged from 6,535-27,775 μg/m3

 (1.2 to 5.1 ppm) at individual industrial sites where TCE was

used (ATSDR, 1997a).

According to ATSDR (1997a), workers, especially in the vapor degreasing industry, are

exposed to the highest levels of TCE through inhalation. These workers may be exposed to
27

levels ranging from approximately 5,446-544,600 μg/m3 (1 to 100 ppm), based on monitoring

survey (ATSDR, 1997a).

1.4.3 Consumer Exposure

Consumer products reported to contain TCE include wood stains, varnishes, and finishes;

lubricants; adhesives; typewriter correction fluids; paint removers; and cleaners (ATSDR,

1997a). Use of TCE has been discontinued in some consumer products (i.e., as an inhalation

anesthetic, fumigant, and an extractant for decaffeinating coffee) (ATSDR, 1997a).

1.5 CHAPTER SUMMARY

Table 1-10 summarizes the findings of TCE.
28

Figure 1-2. Frequency of NPL Sites with Trichloroethylene Contamination (Source: ATSDR,

1997a)
29

Table 1-10. Trichloroethylene Summary

Estimates Support

Uses Metal cleaning and degreasing; many other

solvent applications

Well documented in numerous studies,

recent information

Production 1.45 x 108

 kg/yr 1991 data

Releases All media - 42 million lb/yr (mostly to ai) in

1994

TRI (U.S. EPA, 1996) is primary source, so

current but uncertain due to self reporting

and exemptions

Properties/Fate Volatile, water soluble, stable in air, no

significant bio-degradation or bioconcentration

Well documented in numerous studies,

recent information

Media Levels - Air: mean = 0.88 :g/m3

- Drinking water: 2-7 :g/L

- Groundwater: median = 3 :g/L

- Human blood: mean = 0.017 :g/L

- Some data on food, human milk, and 

other tissues

- Air data is from 1998 survey of 115

monitors in 14 states 

- Based on extensive data from public

water systems which routinely monitor

for TCE, private systems generally do not

monitor for TCE and levels not well

established 

- Groundwater estimate from 1985 survey

of 819 water systems in CA

- Blood data collected from 1988 to 1994 

from 677 individuals

- n’s and dates for other data unclear, but

appear very limited

General Population

Exposure

- Inhalation: 11-33 :g/d (urban)

- Water ingestion: 2-20 :g/d

- Food exposure possible but probably low

- Inhalation and ingestion estimates based

on very limited monitoring data (see

above)

- Insufficient food data for reliable

estimates of exposure

Special Population

Exposures

- Nursing infants

- Workers in production plants or

degreasing operations: 1-100 ppm

- Human milk data insufficient for

estimating exposure

- Worker data based on several recent

surveys
30

2.0 TETRACHLOROETHYLENE (PERCHLOROETHYLENE)

2.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

2.1.1 Nomenclature

CAS No.: 127-18-4

Synonyms: 1,1,2,2-tetrachloroethylene; ethene, tetrachloro-,

perchloroethylene; tetrachloroethene; PCE.

Trade Names: ENT 1; 860; Perclene; Persec; Antisal 1; Dow-Per; Perchlor; Perklone.

2.1.2 Formula and Molecular Weight

Molecular Formula: C2Cl4

Molecular Weight: 165.83

2.1.3 Chemical and Physical Properties

Description: Colorless liquid, ether-like or chloroform-like odor (Merck Index, 10th

Ed., 1983).

Boiling Point: 121° C @ 760 mm Hg (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88).

Melting Point: -19° C (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88).

Density: 1.6227 at 20° C/4° C (Weast. Hdbk. Chem. & Phys., 68th Ed., 

 1987-88).

Spectroscopy

Data: Sadtler Ref. Number: 237 (IR, prism); 79 (IR, grating) (Weast. 

Hdbk.Chem. & Phys., 60th Ed., 1979). Index of refraction: 1.5053

@ 20° C/D (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88). IR:

4786 (Coblentz Society Spectral Collection), Mass: 1053 (Atlas of 

Mass Spectral Collection)

Solubility: Soluble in water, 0.15 g/100 ml @ 25°C (IARC Monographs)

 (1972-present) 1979. Miscible with alcohol, ether, chloroform,

 benzene (Merck Index, 10th Ed., 1983).

Volatility: Vapor Pressure - 18.47 mm Hg at 25°C (Riddick, J.A., et al. (1986)

Organic Solvents: Physical Properties and Methods of Purification).
31

Vapor Density - 5.7 (air = 1) (Browning Tox. & Metab. Indus. Solv.,

 1965).

Stability: Rapidly deteriorates in warm climates (Goodman, 1975);

tetrachloroethylene is stable up to 500°C in the absence of catalysts,

moisture, and oxygen (WHO, Environ. Health Criteria, 1984).

Reactivity: Reacts with metals to form explosive mixtures; sodium hydroxide,

possible explosion (ITII. Tox. & Hazard Indus. Chem. Safety Manual,

1982). Incompatible with chemically active metals, such as barium,

lithium, and beryllium (NIOSH Pocket Guide, 1985).

Octanol/Water

Partition 

Coefficient: log Kow = 3.40 (Hansch C., Leo A.J., 1985, Medchem Project Issue 

 No. 26)

2.1.4 Technical Products and Impurities

Tetrachloroethylene is available in the USA in the following grades: purified, technical,

USP, spectrophotometric, and dry-cleaning. The technical and dry-cleaning grades both meet

specifications for technical grade and differ only in the amount of stabilizer added to prevent

decomposition. Stabilizers include amines or mixtures of epoxides and esters. Typical analysis

of the commercial grade is nonvolatile residue, 0.0003%; free chlorine, none; moisture, no cloud

at -5°C. USP grade contains not less than 99.0% and no more than 99.5% tetrachloroethylene,

the remainder consisting of ethanol (IARC Monographs, 1972-Present V20 492, 1979). PCE is

also available in the United States in veterinary preparation (Nema Worm Capsules) (AMA Drug

Eval., 1986).

2.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

2.2.1 Production

- U.S. Production: (1985) 3.08 x 1011 g; (1986) 1.84 x 1011 g; (1989) 2.14 x 1011 g;

(1990) 1.6 x 1011 g; (1991) 1.08 x 1011 g; (1992) 1.12 x 1011 g; (1993) 1.23 x

1011 g (ATSDR, 1995b; HSDB, 1996).

- Import volumes: (1982) 1.70 x 1010 g; (1985) 6.36 x 1010 g; (1986) 8.3 x 107 g

(Bureau of the Census, U.S. Imports for Consumption and General Imports, 1985;

1986).

- Export volumes: (1983) 2.47 x 1010 g (SRI); (1985) 9.84 x 109

 g (Bureau of the

Census, U.S. Exports, 1985).
32

2.2.2 Uses

The three major uses of tetrachloroethylene in the U.S. are textile dry-cleaning;

processing and finishing in both cold cleaning and vapor degreasing of metals; and as a chemical

intermediate in the synthesis of fluorocarbon 113, 114, 115, and 116. However, because of an

international agreement to protect against ozone layer depletion, this latter use is being phased

out (IARC, 1995). Additionally, PCE is used as a heat-exchange fluid; a scouring, sizing, and

desizing agent; a carrier solvent for fabric dyes and finishes; a water repellant in textile

manufacture; a component of aerosol laundry-treatment products; a solvent for silicones;

insulating fluid and cooling gas in electric transformers (SRI); and a solvent in typewriter

correction fluids (IARC, 1995). Other reported uses are extractant in the pharmaceutical

industry; a pesticide; and a solvent for adhesive formulations, printing inks, leather treatments;

and paper coatings. It has also been reported to be used as an anthelminthic in the treatment of

hookworm and some trematode infestations (IARC, 1995) although it has been replaced now

with other less toxic and easier-to-administer compounds.

The current end-use pattern for PCE is estimated to be 55% for chemical intermediates,

25% for metal cleaning and vapor degreasing, 15% for dry cleaning and textile processing, and

5% for other unspecified uses (ATSDR, 1997b).

2.2.3 Disposal

Incineration at a temperature greater than 450°C is a method of disposal, preferably after

mixing with another combustible fuel. Care must be exercised to assure complete combustion to

prevent the formation of phosgene. An acid scrubber is necessary to remove the halo acids that

are produced (ATSDR, 1997b). PCE may be disposed of in landfills by adsorbing it in

vermiculite, dry sand, earth, or a similar material and disposing in a secured sanitary landfill

(ATSDR, 1997b). According to HSDB (1996), an environmental regulatory agency should be

consulted prior to implementing land disposal of waste containing PCE. The HSDB database

presents numerous disposal practice precautions for carcinogens from the IARC 1979 Scientific

Publication No. 33.

2.3 POTENTIAL FOR HUMAN EXPOSURE

2.3.1 Natural Occurrence

The natural production of PCE in temperate, subtropical, and tropical algae, and in one

red microalga has been reported (IARC, 1995).

2.3.2 Occupational

There is considerable potential for exposure to PCE (dermal and inhalation) during its use

in degreasing and dry cleaning operations (IARC, 1995). Other occupational areas where

exposures may occur are urethane foam, automotive brake, and rubber molding manufacture;

motion picture film processing; taxidermy; electroplating; and graphic arts.
33

2.3.3 Environmental

PCE is released to the environment through industrial emissions, from building products

and consumer products. Releases are primarily to the atmosphere, but there are additional

releases to surface water and land in sewage sludges, other liquids, and solid wastes. Because of

the high vapor pressure, PCE is volatilized to the atmosphere from these sources (ATSDR,

1997b). The Toxic Release Inventory (TRI) industrial release data for PCE releases to air, water,

land, and other media from manufacturing facilities are presented in Table 2-1. The number of

reporting facilities and the total releases per year are also shown in Table 2-1.

2.3.3.1 Environmental Releases

Air: Levels of PCE in air have been reported in numerous studies, both in the U.S. and

worldwide. PCE has been found in ambient air, especially in the near vicinity of dry cleaning

operations. The TRI emission estimate for total PCE industrial emissions to the atmosphere was

32.9 million pounds in 1987; 17 million pounds in 1991; and 5.2 million pounds in 1994 (TRI,

1996).

Water: PCE has been detected in rainwater, surface water, drinking water, and seawater. 

According to TRI, releases to surface water totaled 161,000 pounds in 1987; 7,448 pounds in

1991; and down to 3,872 pounds in 1994 (TRI, 1996).

Other Media: Levels of PCE have been reported in foods, marine invertebrates, fish,

waterbirds, marine mammals, marine sediments, and human blood, urine, breast milk, and tissue

(IARC, 1995; ATSDR, 1997b; HSDB 1996). TRI estimates of releases for land disposal were

618,026 pounds in 1993 down to 4,349 pounds in 1994 (TRI, 1996).

Table 2-1. Releases of Tetrachloroethylene (lbs)

Year

Number of

Reporting

Facilities Fugitive Air

Releases

Stack Air

Releases

Surface

Water

Release

Underground

Injection

Land

Disposal

POTW

Transfer

Other Transfers

Total

1987 715 15,628,341 17,273,459 160,921 354,000 5,220 468,295 9,155,484 43,046,435

1988 746 16,336,282 19,786,265 33,314 72,250 82,144 558,691 5,582,693 42,452,385

1989 732 12,187,707 15,753,023 53,940 50,000 10,791 467,181 4,356,193 32,879,567

1990 666 9,351,150 13,597,042 21,510 11,012 1,260 450,922 4,548,481 27,982,043

1991 577 6,669,093 10,339,157 7,448 14,000 23,309 234,642 16,290,418 33,578,644

1992 518 5,305,402 7,389,816 10,317 12,780 9,354 111,517 11,011,874 23,851,578

1993 490 4,538,411 6,634,275 10,152 15,041 618,026 111,002 9,564,687 21,492,084

1994 459 4,671,751 5,530,378 3,872 4,051 4,349 62,053 10,411,056 20,687,969

Source: TRI, 1996.
34

2.3.3.2 Monitored Environmental Media Levels

Air: Measured levels of PCE in air in rural, urban, and suburban locations in the U.S. are

shown in Table 2-2.

Water: Measurements of PCE in surface waters, groundwater, and drinking water in

U.S. locations are shown in Table 2-3.

Other Media: PCE was reported as a contaminant of cosmetic products (0.3-400 μg/l)

and cough mixtures (0.2-97.1 μg/l) (IARC, 1995). PCE has been detected in blood and urine of

occupationally exposed persons. It has also been reported in 7 of 42 breast milk samples from

the general population in 4 urban areas of the U.S. (IARC, 1995; HSDB, 1996). PCE was

detected at 1.4 - 5.7 ppt in rain/snow in California (HSDB, 1996). Levels found in food included

(ATSDR, 1997b; HSDB, 1996):

C Crab apple jelly - 2.5 μg/kg

C Grape jelly - 1.6 μg/kg

C Dairy products - 0.3 - 13 μg/kg

C Oils and fats - 0.01 - 7 μg/kg

C Beverages (canned fruit drinks, instant coffee, tea) - 2 - 3 μg/kg

C Fruits and vegetables (potatoes, apples, pears, tomatoes) - 0.7 - 2 μg/kg

C Grain-based products (wheat, corn, oats, corn grits, corn meal) - 1.8 - 2.5 μg/kg

Table 2-2. Concentrations of Tetrachloroethylene in Ambient Air

Area

Concentration (ng/m3

)

*

Mean Range

Rural

Southern Washington, USA

Rural California, USA

Central Michigan, USA

USA, 577 sites

136

210

1,085

200-300

Urban and Suburban

New York City, NY, USA

Houston, TX, USA

Detroit, MI, USA

Los Angeles, CA, USA

Phoenix, AZ, USA

Oakland, CA, USA

San Diego, CA, USA

San Francisco, CA, USA

Sacramento, CA, USA

9,017

2,644

3,119

10,034

6,739

2,054

1,831

1,559

475

1,085-71,936

<678-30,510

678-14,916

1,180-14,001

875-25,066

359-9,831

Source: IARC, 1995. * 1 ng/m3

=0.00014 ppb
35

Table 2-3. Concentrations of Tetrachloroethylene in Water

Area

Concentration (μg/L)

Mean Range

Surface Waters:

Seawater

Eastern Pacific

North Atlantic

Rainwater

Los Angels, CA, 1982

La Jolla, CA

Portland, OR

Germany

Rivers

USA, five states, surface water (14% of samples

positive)

Drinking Water

New Jersey, USA, 1981-83

New Jersey, USA

Woburn, MA, USA

0.021

0.006

0.08

0.4

7.7

0.0001-0.0021

0.00012-0.0008

0.0008-0.009

max. 21

max. 14

66-212

Groundwater:

USA, CA, 945 Water supplies

USA, five sites, 28% of samples positive

max. 0.58-69

max. 1500

Source: IARC, 1995.

Levels of PCE detected in margarine from several supermarkets in the Washington, D.C.,

area were $50 ppm in 10.7 percent of the products sampled. The highest levels, ranging from

500 to 5,000 ppb, were found in samples from a store located near a dry cleaning operation

(ATSDR, 1995b). The concentrations were highest on the ends of the margarine stick and

decreased towards the middle, suggesting that contamination occurred after manufacturing rather

than during the manufacturing process (ATSDR, 1997b).

Biological Monitoring: The Third National Health and Nutrition Examination Survey

(NHANES III) examined perchloroethylene concentrations in blood in 590 non-occupationally

exposed individuals (IARC, 1995 and Ashley et al., 1994). This study involved persons in the

general U.S. population who were selected on the basis of age, race, gender and region of

residence. The samples were collected during 1988 to 1994. As shown in Table 2-4 below, the

tetrachloroethylene levels in whole blood span over a wide range with a mean concentration of

0.19 μg/l. This result is also shown on Figure 2-1.
36

Figure 2-1. Concentration of Tetrachloroethylene in Blood at Selected Population Percentiles
37

Table 2-4. Tetrachloroethylene Levels in Whole Blood by Population Percentile*

Percentiles 10 20 30 40 50 60 70 80 90

Concentration (:g/l) 0.015 0.015 0.035 0.049 0.063 0.086 0.120 0.180 0.35

* detection limit = 0.03 :g/L

Source: Personal communication from David Ashley, Center for Disease Control.

Clewell (personal communication to J. Schaum, 1997) applied the NHANES III blood

data for tetrachloroethylene to a physiologically based pharmacokinetic model (described in

Gearhart et al., 1993) to estimate the following quantities: 

C The long term average inhaled air concentration which would result in the

measured blood concentration, assuming no other perchloroethylene exposure. 

C The long term average ingested dose which would result in the measured blood

concentration, assuming no other perchloroethylene exposure. This dose was

converted to a perchloroethylene water concentration assuming an ingestion rate

of 2 l/day.

C For each of these exposure scenarios, the model also provides the corresponding

concentrations of TCA and DCA in blood and the amount of perchloroethylene

metabolized per day.

This model (Gearhart et al., 1993) includes 30 to 40 parameters in its structure. Typically

only 25 to 30 percent of these parameters have a significant enough impact on the model

prediction to be considered. Significant parameters in this model include parameters such as

blood/air and tissue/blood partition coefficients, organ volumes, body weight, ventilation rates,

and in vivo metabolic rates.

Table 2-5 below provides the modeled exposure estimates corresponding to a range of

blood levels.

As shown in Table 2-6 below, the modeled mean perchloroethylene concentrations fall

within the range of measured values for both air and water. 

Further interpretations of this analysis are discussed below:

C The monitoring data are much older than the blood data (collection dates: air

1975-1981, water 1973-1994 and blood 1988 - 1994). Thus, the exposure

estimates derived from blood should better reflect current conditions. 

C Environmental monitoring data (especially for air) may not be very representative

of actual exposures. For example, ambient air monitors are fixed units typically

located on top of buildings and do not sample the air that a person actually 
38

Table 2-5. Modeled Exposure Estimates for Tetrachloroethylene

Blood Level Air Concentration

(:g/m3

)

Ingested Dose

(:g/kg-day)

Water Concentration

(:g/l)

10th percentile (0.015 :g/l) 1.34 0.24 8.4

90th percentile (0.35 :g/l) 31.2 5.5 192.5

Mean (0.19 :g/l) 17.0 3 105

Table 2-6. Comparison of Measured and Modeled Perchloroethylene Concentrations

Measured Range Modeled Mean

Air 0.2 to 30 :g/m3 18.5 :g/m3

Water 0.0001 to 210 :g/l 105 :g/l

breathes throughout a day. Also, indoor air (which is not measured by ambient air

monitors) may be a more important contributor to perchloroethylene exposure

than outdoor air. In contrast, blood measurements reflect the actual exposure that

an individual experiences. Thus, the exposure estimates derived from blood

should more accurately reflect total exposure. 

C Exposure estimates derived from blood cannot distinguish between exposure

routes and sources. It is generally believed that perchloroethylene exposure

occurs primarily via water consumption and air inhalation, but it is impossible to

use the blood data to estimate how much of the total exposure is attributable to

each. A wide range of combinations of exposures from air and water could have

produced the measured blood levels. 

2.3.3.3 Environmental Fate and Transport

2.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of tetrachloroethylene released to

surface soils is volatilization. Because of its low to moderate mobility in soils,

tetrachloroethylene introduced into soil (e.g., landfills) has the potential to migrate through the

soil into groundwater. Biodegradation under anaerobic conditions in soil and groundwater may

occur at a relatively slow rate (half-lives on the order of months or longer (HSDB, 1996).
39

Fate in the Atmosphere: In the atmosphere, tetrachloroethylene is expected to be present

primarily in the vapor phase rather than sorbed to particulates because of its high vapor pressure. 

Removal by scavenging during wet precipitation is expected because of the moderate solubility

of tetrachloroethylene in water (150 mg/L). The major degradation process affecting vapor phase

tetrachloroethylene is photo-oxidation by hydroxyl radicals and the chlorine radicals formed by

the hydroxyl radical reaction (half-life on the order of weeks to months).

Fate in Aquatic Environments: The dominant fate of tetrachloroethylene released into

surface waters is volatilization (predicted half-life of hours to days (HSDB, 1996)). 

Bioconcentration and sorption to sediments and suspended solids are not expected to be

significant transport/partitioning processes. Although biodegradation is not expected to be a

significant degradation process, any tetrachloroethylene that reaches the sediment will undergo

slow anaerobic biodegradation.

2.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: A Koc of 1,685 is predicted for tetrachloroethylene based on

its measured log octanol/water partition coefficient of 3.40. Actual Kocs calculated from studies

with various soils and sediments are less than 250 (HSDB, 1996). Based on the reported and

measured Kocs, tetrachloroethylene is expected to exhibit low to medium mobility in soil. 

Therefore, tetrachloroethylene may leach slowly to the groundwater particularly in soils with low

organic content (HSDB, 1996).

Volatilization: The dominant removal mechanism for tetrachloroethylene in surface

waters is volatilization. The half-life will depend on wind and mixing conditions and is

estimated to range from 3 hours to 14 days in rivers, lakes, and ponds based on laboratory and

mesocosm experiments. Because of its high vapor pressure and relatively low soil adsorption

coefficient, tetrachloroethylene is expected to volatilize from soil surfaces and also from

suspended particulate matter in the atmosphere (HSDB, 1996).

Bioconcentration: A bioconcentration factor of 226 is predicted for tetrachloroethylene

based on its measured log octanol/water partition coefficient of 3.40. Actual BCFs measured in

fish studies are less than 50. Therefore, bioconcentration in aquatic organisms should not be

significant and there is little potential for biomagnification in the food chain (HSDB, 1996).

2.3.3.3.3 Transformation and Degradation Processes

Biodegradation: Under aerobic conditions, tetrachloroethylene undergoes

biodegradation at a very slow rate with a half-life estimated at 6 months to a year. Little or no

degradation has been observed in several aerobic tests with acclimated or unacclimated inocula

nor in river die-away and mesocosm tests. Slow degradation under anaerobic conditions (halflives of weeks to months) has been demonstrated in laboratory screening tests. 

Trichloroethylene is the major intermediate observed with traces of vinyl chloride and

dichloroethylene isomers also formed (HSDB, 1996; Howard et al., 1991).
40

Photodegradation: Photolysis in the atmosphere or in aquatic environments is expected

to proceed very slowly if at all. Tetrachloroethylene does not absorb UV light at wavelengths

greater than 260 nm and thus will not directly photolyze. Based on measured rate data for the

vapor phase photo-oxidation reaction with hydroxyl radicals and with the chlorine radicals

formed during this reaction, the estimated half-life of tetrachloroethylene in the atmosphere is on

the order of weeks to months, although one study has reported complete degradation in one hour. 

The main reaction products are phosgene, carbon tetrachloride, dichloroacetyl chloride, and

trichloroacetyl chloride (HSDB, 1996; Howard et al., 1991).

Hydrolysis: Tetrachloroethylene has no hydrolyzable groups. The rate constants at pH 3,

7, and 11 have been measured to be zero in one study. Another study reported a half-life of 9

months in purified, deionized water (HSDB, 1996; Howard et al., 1991)

2.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

2.4.1 General U.S. Population

The most important routes of exposure to PCE for the general population are inhalation

of PCE in ambient air and ingestion of contaminated drinking water from contaminated aquifers

and drinking water distributed in pipelines with vinyl liners (HSDB, 1996). Available data

indicates that dermal exposure to PCE is not an important route of exposure for most people

(ATSDR, 1997b). Exposure from inhalation of ambient air varies according to location. In rural

and remote areas, background levels are generally in the low ppt range, and both low ppb and

high ppt are found in urban and industrial areas, and areas near point sources of emissions

(ATSDR, 1997b).

Results of several studies have indicated that indoor air is a more significant source of

exposure to PCE than outdoor air; reported concentrations in the air of four homes in North

Carolina were consistently higher than the outdoor concentrations (ATSDR, 1997b). The

detection of PCE in breast milk (see Section 2.3.3.2) indicates that infants may be exposed to

PCE through breast feeding (ATSDR, 1997b). For the general population, the estimated amount

of PCE that a person might breathe per day ranges from 0.08-0.2 mg/day and the most PCE

people might drink in water is 0.0001-0.002 mg/day (ATSDR, 1997b).

The EPA estimated that in 1985, 11,430,000 individuals (5.3 percent of the U.S.

population using municipal water supplies) in the U.S. were exposed to PCE at concentrations

$0.5 μg/l. Assuming a 70 kg person drinks 2 L/day of water containing 0.5 ppb PCE, the daily

intake of PCE was 1 μg or 0.014 μg/kg/day (ATSDR, 1997b). Additionally, 874,000 individuals

were estimated to be exposed to levels >5 μg/l (IARC, 1995). General population exposure from

ingestion of contaminated foods has been approximated by EPA assuming individual average

daily intakes of 0.753 kg dairy products; 0.262 kg meat, fish, and poultry; 0.073 kg fats and oils;

and 0.128 kg beverages (ATSDR, 1997b). The average daily intake of PCE was determined to

be between 0-4 μg from dairy products; 0-1 μg from meat, fish, and poultry; 0-9.5 μg from fats

and oils; and 0-0.06 μg from beverages (ATSDR, 1997b).
41

Showering or bathing with contaminated water is also a mechanism for PCE exposure. 

Using results from a study and a model, it was estimated that the shower air would contain an

average of 1 ppm and the air above a bath tub would contain an average of 0.725 ppm if the

water contained 1 mg/L of PCE (ATSDR, 1997b). The model assumed that the shower or bath

used 100 liters of water, the air volume in the shower stall or above the bath tub was 3 m3

, and

the shower flow rate was 6.667 L/minute (ATSDR, 1997b).

2.4.2 Occupational Exposure

Persons with the greatest chance of elevated exposure are those engaged in occupational

activities using PCE. In a survey conducted between 1981 and 1983 by NIOSH, it was estimated

that approximately 688,110 employees in 49,025 plants in the U.S. were potentially exposed to

PCE (ATSDR, 1997b). Further, in 1994 an independent industry estimate indicated that

approximately 450,000 workers in dry cleaning operations in the U.S. may be exposed (IARC,

1995). A NIOSH survey in 44 dry cleaning facilities showed PCE TWA exposures to machine

operators ranged from 4.0 to 149 ppm with a geometric mean of 22 ppm. Mean exposures to

pressers, seamstresses, and front counter workers were 3.3, 3.0, and 3.1 ppm, respectively

(ATSDR, 1997b).

Tetrachloroethylene has been identified in at least 771 of 1,430 hazardous waste sites that

have been proposed for inclusion in the EPA National Priorities List (NPL) (ATSDR, 1997b). 

The number of sites evaluated is not known; the frequency of the sites are shown in Figure 2-2.

2.4.3 Consumer Exposure

In a study to determine potential sources of indoor air pollution, approximately 63 of

1,159 common household products were found to contain PCE (IARC, 1995). Products that 

may contain PCE include adhesives; water repellents; fabric finishers; stain, spot, and rust

removers; and wood cleaners (ATSDR, 1997b). Other consumer products that have been found

to contain PCE are inks, polishes, rug and upholstery cleaners, sealants, and silicones.

2.5 CHAPTER SUMMARY

Table 2-7 summarizes the findings of TCE.
42

Figure 2-2. Frequency of NPL Sites with Tetrachloroethylene Contamination (Source: ATSDR,

1997b)
43

Table 2-7. Tetrachloroethylene (Perchloroethylene) Summary

Estimates Support

Uses Dry cleaning and metal degreasing Well documented in numerous studies,

recent information

Production 1.2 x 108

 kg/yr 1993 data

Releases Air: 5.2 million lb/yr

Water: 3,900 lb/yr

Land: 4,300 lb/yr

TRI (U.S. EPA, 1996) is primary source, so

current but uncertain due to self reporting

and exemptions

Properties/Fate Volatile, water soluble, photo-oxidizes

slowly in air, no significant biodegradation

or bioconcentration

Well documented in numerous studies,

recent information

Media Levels - Urban air: low ppb

- Rural air: low ppt

- Drinking water: 0.5-5 ug/L

- Food: 0.3-3 ug/kg

- Human blood: 0.19 ug/L

- Human milk: 6.2 ug/L

- Air data represents only 4 rural and 9

urban locations, dates unclear

- Blood data from NHANES III (n=590)

- n’s and dates unclear for water, food, and

human milk data

General Population

Exposure

- Inhalation: 0.08-0.2 mg/d (urban)

- Water ingestion: 0.1-2 ug/d

- Dairy: 0-4 ug/d

- Meat: 0-1 ug/d

- Fats/oils: 0-9 ug/d

- All estimates based on limited or unclear

monitoring data (see above)

Special Population

Exposures

- Nursing infants: ~4 ug/d

- Workers in production plants, degreasing

operations, dry cleaners (3-150) ppm

- Representativeness of human milk data

unknown

- Worker data based on several recent 

surveys
44

3.0 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM)

3.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

3.1.1 Nomenclature

CAS No.: 71-55-6

Synonyms: Chloroethene; chloroform; methyl-, chlorotene; ethane,

1,1,1-trichloro-; methyl chloroform; trichloroethane

Trade Names: alpha-t; algylen; baltana; gemalgene; inhibisol; solvent 111

3.1.2 Formula and Molecular Weight

Molecular Formula: C2H3Cl3

Molecular Weight: 133.43

3.1.3 Chemical and Physical Properties

Description: Colorless liquid (Patty, 1981-82); chloroform-like odor, sweetish

(Hazard Chem. Data Vol. II, 1984-85).

Boiling Point: 74.0°C @ 760 mm Hg (CRC Handbook Chem. & Physics, 1994-

95).

Melting Point: -30.4°C (CRC Handbook Chem. & Physics, 1994-95).

Density: 1.3376 @ 20°C/4°C (Merck Index, 11th Ed., 1989).

Spectroscopy Data: Index of refraction: 1.43838 @ 20°C/D (Merck Index, 10th Ed.,

1983); IR: 19461, NMR: 9171; Mass; 618 (Sadtler Research

Laboratories Prism Collection) (Weast, 1985).

Solubility: Soluble in acetone, benzene, methanol, carbon tetrachloride

(Merck Index, 11th Ed., 1989); 4,400 mg/l in water @ 20°C

(Verschueren, 1983).

Volatility: Vapor Pressure: 16.5 kPa @ 25°C (CRC Handbook, 1994-95)

Vapor Density: 4.63, relative (air = 1) (Verschueren, 1983).

Stability: No data.
45

Reactivity: Although apparently stable on contact, mixtures with potassium

(or its alloys) with a wide range of halocarbons (including 1,1,2-

trichloroethane) are shock-sensitive and may explode with great

violence on light impact. Violent decomposition with evolution

of hydrogen chloride may occur when it comes into contact with

aluminum or its alloys with magnesium (Handbook Reactive

Chem. Hazards, 1985). Reacts with strong caustics; strong

oxidizers; chemically-active metals such as zinc, magnesium

powders; sodium and potassium; water (note: reacts slowly with

water to form hydrochloric acid) (NIOSH Pocket Guide Chem.

Haz, 1994).

Octanol/Water

Partition Coefficient: log Kow = 2.49 (Hansch. Log P Database, 1984)

3.1.4 Technical Products and Impurities

1,1,1-Trichloroethane is available commercially in the USA in technical and solvent

grades, which differ only in the amount of stabilizer added to prevent corrosion of metal parts

(IARC Monographs, V20:516, 1979). It is available as chlorothene SM (industrial grade) and

aerothene TT (aerosol grade) (Kuney. Chemcyclopedia, 1988).

Impurities include 1,2-dichloroethane, 1,1-dichloroethane, chloroform, carbon

tetrachloride, trichloroethylene, 1,1,2-trichloroethane, and vinylidene chloride (Stewart, RD, et

al., 1969).

Stabilized grades contain 3-8% stabilizers such as nitromethane, N-methylpyrrole,

butylene oxide, 1,3-dioxolane, and secondary butyl alcohols (IARC Monographs, V20:516,

1979). Stabilizing agents which may be present in small amounts include: glycol diesters,

ketones, nitriles, dialkyl sulfoxides, dialkyl sulfides, dialkyl sulfites, tetraethyl lead, nitroaliphatic

hydrocarbons, 2-methyl-3-butyn-2-ol, tert-butyl alcohol, 1,4-dioxane, dioxolane, sec-butyl

alcohol, and monohydric acetylenic alcohols (NIOSH, 1976).

3.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and from

ATSDR (1995).

3.2.1 Production

- (1990) 3.64 x 1011 g (ATSDR, 1995); (1992) 3.13 x 1011g (HSDB, 1996).

- Import Volume: (1991) 4.54 x 107 g; (1992) 5.99 x 109 g; (1993) 9.08 x 107 g

(ATSDR, 1995).
46

- Export Volume: (1990) 5.2 x 1010 g; (1991) 7.37 x 1010 g; (1992) 6.34 x 1010 g; (1993)

3.44 x 1010 g (ATSDR, 1995).

3.2.2 Uses

1,1,1-Trichloroethane is used as a solvent for adhesives (including food packaging

adhesives) in pesticides, metal degreasing, textile processing, aerosols, lubricants, cutting oil

formulations, cutting fluids, shoe polishes, spot cleaners, stain repellents, drain cleaners, and

printing inks (ATSDR, 1995; HSDB, 1994). Its primary use in industry is for cold, dip, and

bucket cleaning and in vapor degreasing operations of electric and electronic instruments, fabrics,

wigs, and photographic film (ATSDR, 1995). It is also used as a chemical intermediate and for

on-site cleaning of printing presses, food packaging machinery, and molds (ATSDR, 1995;

HSDB, 1996). 1,1,1-Trichloroethane is also used extensively in household products that contain

solvents. 

3.2.3 Disposal

Generators of waste containing this contaminant (i.e., EPA hazardous waste numbers

U226 and F002) must conform with USEPA regulations in storage, transportation, treatment, and

disposal of waste [40 CFR 240-280, 300-306, 702-799]. 1,1,1-trichloroethane is a waste

chemical stream constituent which may be subjected to ultimate disposal by controlled

incineration, preferably after mixing with another combustible fuel. Complete combustion to

prevent the formation of phosgene must be exercised (U.S. EPA, 1981 Engineering Handbook

for Hazardous Waste Incineration). 1,1,1-Trichloroethane is a potential candidate for liquid

injection incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2

seconds; for rotary kiln incineration at a temperature range of 820 to 1,600°C and residence times

of seconds for liquids and gases, and hours for solids; and for fluidized bed incineration at a

temperature range of 450 to 980°C and residence times of seconds for liquids and gases, and

longer for solids (HSDB, 1996). Chemical treatability study results indicates that the chemical

may be extractable with solvents, air and stream strippable, and treatable using biological

treatment (U.S. EPA, 1982, Management of Hazardous Waste). Other methods that have shown

promise for destruction of 1,1,1-trichloroethane are a combination of ozonation and ultraviolet

treatment for groundwater and homogeneous sonochemical treatment for aqueous waste

(ATSDR, 1995).

3.3 POTENTIAL FOR HUMAN EXPOSURE

3.3.1 Natural Occurrence

1,1,1-Trichloroethane is not known to occur as a natural product.

3.3.2 Occupational

Humans may be exposed to 1,1,1-trichloroethane dermally and by inhalation of

contaminated air at the workplace (HSDB, 1996).
47

3.3.3 Environmental

1,1,1-Trichloroethane is likely to enter the environment from air emissions or in the

wastewater from its production or use in vapor degreasing, metal cleaning, and other operations. 

It can also enter the environment in leachates and volatile emissions from landfills (HSDB,

1996). Process and fugitive emissions may result from the use of both consumer and industrial

products (ATSDR, 1995). Because 1,1,1-trichloroethane is used as a solvent in many products

and is very volatile, it is most frequently found in the atmosphere due to volatilization from

production and use (ATSDR, 1995).

3.3.3.1 Environmental Releases

Air: Trichloroethane has been found in the ambient air around chemical manufacturing

areas, in remote and rural areas, and around suburban sites. Toxic Release Inventory (TRI) data

are shown in Table 3-1.

The TRI data for 1,1,1-trichloroethane have been correlated with industrial source code

(SIC Codes) and shows that emissions of this chemical are associated with 122 different

industrial classifications (ATSDR, 1995). The TRI data shown in Table 3-1 indicate that 1,1,1-

trichloroethane emissions to air ranged from 166.3 million pounds in 1987 down to 38.1 million

pounds in 1994 (TRI, 1996).

Table 3-1. Releases of 1,1,1-Trichloroethane (lbs)

Year

Number of

Reporting

Facilities Fugitive Air

Releases

Stack Air

Releases

Surface

Water

Release

Underground

Injection

Land

Disposal

POTW

Transfer

Other

Transfers Total

1987 3494 90,428,647 75,825,060 37,181 28,325 199,191 412,010 32,141,143 199, 071,557

1988 3915 92,995,587 87,654,575 95,624 1,000 204,923 305,358 19,389,542 200,646,609

1989 4201 94,100,022 86,086,417 27,564 2,318 70,547 312,515 16,815,840 197,415,223

1990 4210 85,672,408 83,0994,85 16,984 1,586 62,446 173,444 13,099,706 182,126,059

1991 3732 72,670,441 71,770,764 22,308 2,805 174,730 253,812 39,451,571 184,346,431

1992 3210 57,760,109 59,857,572 13,707 561 76,131 119,263 32,080,182 149,907,525

1993 2111 33,199,831 31,568,263 11,146 2528 42,743 60,463 20,842,953 85,727,927

1994 1207 20,070,741 17,981,336 1,980 102 2,732 6,439 11,387,618 49,450,948

Source: TRI, 1996.
48

Other sources for small emissions of 1,1,1-trichloroethane to the atmosphere include coal

fired plants, incineration of medical waste, incineration of industrial waste containing waste

solvents and certain plastics, and municipal wastewater sludge (ATSDR, 1995). When contained

in consumer products, 1,1,1-trichloroethane can be released to the atmosphere during application,

drying, or curing of the consumer products.

Water: 1,1,1-Trichloroethane has been reported in groundwater, surface water, and

drinking water in the United States. It has also been reported in seawater. TRI data on water

releases are presented in Table 3-1.

Other Media: Levels of 1,1,1-trichloroethane has been reported in raw, processed, and

prepared foods. Additionally, it has been detected in soils and sediments (ATSDR, 1995). TRI

estimates of releases to land are presented in Table 3-1.

3.3.3.2 Monitored Environmental Media Levels

Air: Numerous studies have reported levels of 1,1,1-trichloroethane in air throughout the

U.S. Monitoring data have been reported with sampling dates ranging primarily from years 1972

through 1986. However, there are several studies for years 1987 through 1990. Measured

concentrations in urban air range from 0.1 to 1 ppb; for large urban areas or areas near hazardous

waste sites, levels #1,000 ppb have been observed (ATSDR, 1995; HSDB, 1996). Level of this

chemical in rural areas typically are <0.2 ppb. ATSDR (1995c) provides a summary of

monitored levels in ambient air in the U.S. that includes sampling dates, number of samples,

concentrations (range and mean), study location, and author. Level of 1,1,1-trichloroethane in

indoor air seems to depend on parameters such as outdoor concentration, age of building,

individual practices, and building air exchange characteristics (ATSDR, 1995).

Water: 1,1,1-Trichloroethane has been detected in surface water, groundwater, drinking

water, rain, snow, effluent, and urban runoff (ATSDR, 1995). The levels detected in surface

water and groundwater depends upon the sampling point location. For groundwater random

samples, levels have ranged from 0 to 18 ppb; groundwater samples obtained near sources of

release to soil have been as high as 11,000 ppb (ATSDR, 1995). Drinking water from reported

surface or groundwater sources contained concentrations of 0.01 to 3.5 ppb (ATSDR, 1995).

Levels in raw surface water in 105 U.S. cities were 0.2 ppb (median) and 1.2 ppb

(maximum) (HSDB, 1996). In studies of surface water near industrialized sites, the measured

levels ranged up to 334 ppb (HSDB, 1996).

Other Media: 1,1,1-Trichloroethane has been detected in human adipose tissues (not

detected - 830 ppb); milk; blood; and breath. It has been found in foods which include

unprepared, uncooked foods; fruits; nuts; dairy products; etc. A range of the mean values for

levels of 1,1,1-trichloroethane reported in ATSDR (1995) are shown in Table 3-2 for some of

these foods. 1,1,1-Trichloroethane has been found in average concentrations in fish at 2.7 ppm;

shrimp at <0.3 ppm; and clams and oysters ranging from 39 to 310 ppm.
49

Table 3-2. Level of 1,1,1-Trichloroethane in Food

Food Type Concentration (ppb) (Range of Means)

Cereals

Vegetables (processed/cooked)

Baked goods (breads, cookies, cakes)

Dairy products

Nuts/nut products

Meats, meat dishes (cooked/processed)

Fruits (raw/dried)

Infant/toddler blend

3-35

1-9

2-40

1-520

10-228

2-76

2-32

6

Source: ATSDR, 1995.

The National Health and Nutrition Examination Survey (NHANES III) (1988-91) is a

national survey of the U.S. civilian non-institutionalized population. It provides data to monitor

changes in dietary, nutritional, and health status of the U.S. population. As part of this survey,

data were analyzed for the level of selected VOCs in the blood. Figure 3-1 presents the level of

1,1,1-trichloroethane in blood at selected percentiles.

Levels of 1,1,1-trichloroethane in soils have been measured in grab samples from two

former sludge lagoons of a solvent recovery operation, at a residence near a landfill, at a

production facility, and at several NPL sites. The reported levels were 23,000 to 120,000 ppb at

the lagoon, up to 230,000 ppb at the NPL sites, and 0.06 to 1.0 ppb at the production facility

(ATSDR, 1995). Levels of 1,1,1-trichloroethane in sediment have been reported up to 2 ppb for

non-NPL sites and ranged from 50 to 2,500 ppb at an NPL site (ATSDR, 1995). Monitoring data

for the occurrence of 1,1,1-trichloroethane in soil is limited and may be due to its rapid

volatilization from soil and/or its ability to leach through soil (ATSDR, 1995).

3.3.3.3 Environmental Fate and Transport

3.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of 1,1,1-trichloroethane released

to surface soils is volatilization. Because of its moderate mobility in soils, 1,1,1-trichloroethane

introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater.

Fate in the Atmosphere: In the atmosphere, 1,1,1-trichloroethane is expected to be

present primarily in the vapor phase rather than sorbed to particulates because of its moderate

vapor pressure. Removal by scavenging during wet precipitation is expected because of the

moderate solubility of 1,1,1-trichloroethane in water; 40 percent reductions in air concentrations

have been reported on rainy days. The major degradation process affecting vapor phase 1,1,1-

trichloroethane is photo-oxidation by hydroxyl radicals (half-life on the order of years). Due to

its persistence, 1,1,1-trichloroethane will disperse over long distances and slowly diffuse into the 
50

Figure 3-1. Concentration of 1,1,1-Trichloromethane in Blood at Selected Population Percentiles
51

stratosphere where it would be rapidly degraded. The global atmospheric average half-life has

been estimated to be 6 to 7 years (HSDB, 1996; ATSDR, 1995).

Fate in Aquatic Environments: The dominant fate of 1,1,1-trichloroethane released to

surface waters is volatilization (predicted half-life of hours to weeks depending on wind and

mixing conditions). Bioconcentration and sorption to sediments and suspended solids are not

expected to be significant transport/partitioning processes relative to volatilization.

3.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: The mean Koc range of 1,1,1-trichloroethane in a silty clay

soil and sandy loam soil is 81 to 89. 1,1,1-Trichloroethane is sorbed strongly to peat moss but

not at all to sand. From these measured Kocs and the fact that 1,1,1-trichloroethane is frequently

detected in groundwater, it can be concluded that 1,1,1-trichloroethane is not sorbed strongly by

soils. It can be expected to leach to groundwater particularly in soils with low organic content

(HSDB, 1996).

Volatilization: The dominant removal mechanism for 1,1,1-trichloroethane in surface

waters is volatilization. The half-life will depend on wind and mixing conditions and is

estimated to range from 3 to 29 hours in rivers, 4 to 12 days in lakes, and 5 to 11 days in ponds

based on laboratory experiments. Because of its moderate vapor pressure and relatively low soil

adsorption coefficient, 1,1,1-trichloroethane is expected to volatilize from soil and also from

suspended particulate matter in the atmosphere. The cumulative evaporation loss of a mass of

1,1,1-trichloroethane situated 1.0 to 1.3 meters beneath a soil surface for one year has been

estimated to be 61.8 percent in sandy soil and 4.9 percent in clay soil (HSDB, 1996).

Bioconcentration: A bioconcentration factor of 8.9 was measured in a 28-day test with

bluegill sunfish. BCFs measured in fish studies are less than 10 for structurally similar

halogenated aliphatic compounds. Therefore, bioconcentration in aquatic organisms should not

be significant and there is little potential for biomagnification in the food chain (HSDB, 1996).

3.3.3.3.3 Transformation and Degradation Processes

Biodegradation: 1,1,1-Trichloroethane has been shown to undergo reductive

dechlorination to 1,1-dichloroethane and chloroethane under anaerobic conditions in laboratory

tests using acclimated microorganisms with half-lives on the order of weeks to months. 

Biodegradation under aerobic conditions has also been demonstrated to occur at a slow rate

(weeks to months) with vinylidene chloride formed as a degradation product (HSDB, 1996;

Howard et al., 1991).

Photodegradation: Direct photolysis is not important in the troposphere since 1,1,1-

trichloroethane does not absorb light above 290 nm. In the stratosphere, photolysis is important

and 1,1,1-trichloroethane will be rapidly degraded. Photolytic degradation has not been observed

in aqueous media exposed to sunlight for one year. Based upon measured rate constants for the

vapor phase photo-oxidation reaction with photochemically produced hydroxyl radicals, the halflife of 1,1,1-trichloroethane in the atmosphere is on the order of years. Products of
52

photodegradation include phosgene, chlorine radicals, and hydrochloric acid. Degradation is

reported to be greatly increased by exposure to ozone and chlorine but no quantitative data are

available (HSDB, 1996; Howard et al., 1991).

Hydrolysis: The hydrolysis half-life of 1,1,1-trichloroethane has been reported to range

from 0.73 to 1.1 years. The half-life in water containing suspended sediment is 1.2 years. The

product of hydrolysis is vinylidene chloride (HSDB, 1996; Howard et al., 1991).

3.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

3.4.1 General U.S. Population

The general population may be exposed to 1,1,1-trichloroethane through the inhalation of

ambient air and inhalation of indoor air contaminated by use of household products containing

this chemical. The general population may be potentially exposed to 1,1,1-trichloroethane

through emissions from hazardous waste sites. 1,1,1-Trichloroethane has been identified at 696

of 1,408 NPL hazardous waste sites. The frequency of these sites in the U.S. is shown in Figure

3-2. Inhalation is expected to be the predominant exposure route; however, exposure can also

occur through ingestion of contaminated foods and drinking water and through dermal contact. 

Therefore, available data suggest that because of its ubiquitous occurrence in the environment

and its use in many consumer products, much of the general population is exposed to low levels

of 1,1,1-trichloroethane (ATSDR, 1995).

Exposure of the general population from the commercial use of products may potentially

be more significant than exposure resulting from industrial release. ATSDR reported maximum

exposure levels to this chemical during a variety of personal activities: visiting the dry cleaners

(185 ppb); working in chemistry lab (18.5 ppb) and as lab technician (12 ppb); using pesticides

(20 ppb); and using paint (20 ppb) (ATSDR, 1995).

The average daily intake (ADI) for air is assumed in HSDB (1996) to be: in rural areas

(0.110 ppb) - 12.2 μg; urban/suburban areas (0.420 ppb) - 46.5 μg; for residents in source

dominated areas assume (1.2 ppb) - 133.0 μg. The ADI for water is assumed in HSDB (1996) to

be: surface water source (0.4 ppb) - 0.8 μg; groundwater source (2.1 ppb) - 4.2 μg. ATSDR

(1995) assumed an average urban air concentration of 1,1,1-trichloroethane of 1 ppb and the

average rural concentration of 0.1 ppb and calculated daily nonoccupational intakes of 108 and

10.8 μg/day, respectively. The estimate is based on an average human air intake of 20 m3

/day. 

ATSDR (1995) noted that Wallace et al. (1985) has determined the mean daily air exposures for

12 subjects at 2 urban areas at 37 mg and the mean daily intake from all sources (air, food, water)

between 50 and 1,000 mg/day.

3.4.2 Occupational Exposure

NIOSH estimated in a 1981-1983 survey that approximately 2,528,300 workers were

potentially exposed to 1,1,1-trichloroethane in the U.S. (ATSDR, 1995). Trichloroethane

concentration in the air of various industries (degreasing, manufacture of electric components, 
53

March 29, 200163

Figure 3-2. Frequency of NPL Sites with 1,1,1-Trichloromethane Contamination (Source:

ATSDR, 1995)
54

mixing and application of commercial resins, spray painting, and gluing) applications of 1,1,1-

trichloroethane might result in elevated levels of exposure (ATSDR, 1995). Occupational

exposures predominantly occur through inhalation pathways.

3.4.3 Consumer Exposure

In a shelf survey for household products containing methylene chloride, 14.1 percent of

the samples and 47.8 percent of the product categories contained 1,1,1-trichloroethane (HSDB,

1996). Consumer products that may contain this chemical include typewriter correction fluid,

fingernail polish, paint thinner, caulking compounds, lacquer, paint removers, and antifreeze. A

list of common household products that contain 1,1,1-trichloroethane is presented in Table 3-3.

Table 3-3. 1,1,1-Trichloroethane in Common Household Products

Product

Concentration

(% w/w) Product

Concentration

(% w/w)

Adhesive cleaners

Adhesives

Aerosol spray paint

Battery terminal protectors

Belt lubricants

Brake cleaners

Carburetor cleaners

Circuit board cleaners

Door spray lubricants

Drain cleaner (nonacid)

Electric shaver cleaners

Engine degreasers

Fabric finishes

Gasket removers/adhesives

General purpose spray degreasers

General purpose liquid cleaners

Ignition wire driers

Lubricants

Miscellaneous nonautomotive

Miscellaneous automotive

0.1-95.0

0.2-121.1

0.2-1.0

37.1

11.4-72

0.4-75.6

0.2-0.3

NS

95.6

97.8

2.5-20.3

0.2

77.9-85.1

0.2-1.0

0.1-71.4

72.7-126.7

24.3-43.6

0.1-104.5

12.5-67.5

0.3-0.4

Oven cleaners

Paint removers/strippers

Primers

Rust removers

Silicone lubricants

Specialized aerosol cleaners

Spot removers

Spray shoe polish

Stereo/record player cleaners

Suede protectors

Tape recorder cleaners

Tire cleaners

Transmission cleaner/lubricant

TV/computer screen cleaners

Typewriter correction fluid

VCR cleaners

Video disk cleaners

Water repellents

Wood cleaners

Woodstain/varnishes/finishes

97

0.1-25.7

1.2-61.8

0.7

0.2-91.1

0.2-83.8

10.5-110.8

11.4-62.3

0.7

4.8-118.5

0.2-101.5

0.1-90.3

113

0.3

6-110

97.8

0.6

0.2-116.2

12.3-20.4

0.1-21.4

NS = not specified

Source: ATSDR (1995)

3.5 CHAPTER SUMMARY

Table 3-4 summarizes the findings of 1,1,1-trichloroethane.
55

Table 3-4. 1,1,1-Trichloroethane (Methyl Chloroform) Summary

Estimates Support

Uses Metal cleaning and degreasing, many

other solvent applications, chemical

intermediate, many household

products

Well documented in recent

studies

Production 3.13 x 108 kg 1992 data

Releases 49.45 x 106 lbs in 1994, mostly to air TRI (U.S. EPA, 1996) data is

primary source, so data are

current but uncertain due to self

reporting and exemptions

Properties/Fate Volatile, no significant bioconcentration, slow bio-degradationWell documented in recent

studies

Media Levels Air: outdoor urban - 0.545-5.45

:g/m3

outdoor rural - <1.09 :g/m3

Drinking Water: 0.01-3.5 ppb

Groundwater: 0-18 ppb

Some data on food and in many

household items

Data is dated and represent

uncertain number of samples

General Population

Exposure

Inhalation: rural - 12.2 :g/d

urban/suburban - 46.5

:g/d

Water ingestion: surface water - 0.8

:g/d; groundwater - 4.2 :g/d

Values based on limited data

Special Population

Exposures

Workers in dry cleaning, chemistry

labs, lab tech, painting

Data limited
56

4.0 1,2-DICHLOROETHYLENE

4.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

4.1.1 Nomenclature

CAS No.: 540-59-0

Synonyms: 1,2-dichloroethene; acetylene dichloride; ethene, 1,2-dichloro

Trade Names: Diform, NCI.C5603

4.1.2 Formula and Molecular Weight

Structural Formula: C2H2Cl2

Molecular Weight: 96.95

4.1.3 Chemical and Physical Properties

Description: Colorless liquid (usually a mixture of cis and trans isomers);

slightly acrid, chloroform-like odor (NIOSH Pocket Guide Chem.

Haz., 1994).

Boiling Point: 55°C (Merck Index, 9th Ed., 1976).

Melting Point: -50°C (Patty. Indus. Hyg. & Tox., 3rd Ed., 1981-82).

Density: 1.27 @ 25°C (liquid) (CHRIS Hazard Chem. Data Vol. II, 

1984-5).

Spectroscopy Data: IR: 3645 (Sadtler Research Laboratories Prism Collection); Mass:

203 (Atlas of Mass Spectral Data) (Weast. 1985. CRC Handbook

Data Organic CPDS, Vol. I, II).

Solubility: Soluble in alcohol, ether, acetone (cis- and trans-1,2-

dichloroethylenes) (CRC Handbook Chem. & Physics, 1994-1995). 

Soluble in most organic solvents (Merck Index, 11th Ed., 1989)

Volatility: Vapor Pressure: 324 torr at 25°C (Patty. Indus. Hyg. & Tox, 3rd.

Ed., Vol. 2A, 2B, 2C, 1981-1982).

Stability: Gradually decomposed by air, light, and moisture, forming HCl

(Merck Index, 10th Ed., 1983).
57

Reactivity: The reaction of 1,2-dichloroethylene and potassium hydroxide

produces chloroacetylene, which is explosive and spontaneously

flammable in air. It is highly toxic. The addition of sodium,

caustic, or caustic solution to 1,2-dichloroethylene may form

monochloroacetylene which is spontaneously flammable in air

(Fire Protect Guide Hazard Matls, 10th Ed., 1991). May release

explosive chloroacetylene by the contact with copper or copper

alloys (Tox & Hazard Indus Chem Safety Manual, 1988). 

Incompatible with alkalies, difluoromethylene dihypofluorite, and

nitrogen tetraoxide (Sax, 1984). Reactive with strong oxidizers,

strong alkalis, potassium hydroxide, copper (Note: usually contains

inhibitors to prevent polymerization) (NIOSH Pocket Guide Chem

Haz, 1994).

Octanol/Water

Partition Coefficient: No data

4.1.4 Technical Products and Impurities

1,2-Dichloroethylene is produced in the following grades: technical; As cis, trans; and as

a mixture of both (Sax, 1987). Technical 1,2-dichloroethylene consists of 60%, 40% cis- transisomers (ACGIH, 1985).

4.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and ATSDR

(1996a).

4.2.1 Production

No information concerning U.S. production, import, or export volumes was identified.

4.2.2 Uses

1,2-Dichloroethylene has been used as a solvent for fats, phenol, camphor; for retarding

fermentation (Merck Index, 11th Ed., 1989); solvent for natural rubber; coolant in refrigeration

plants; low temperature solvent; and a special-purpose solvent (HSDB, 1996; ATSDR, 1996a). 

It has also been used in extraction of dyes, caffeine, fats from animal flesh; perfumes; lacquers;

thermoplastics; and organic synthetics (Sax, 1987). Although cis- and trans-isomers of 1,2-

dichloroethylene have had use as solvents and chemical intermediates, neither of the isomers has

developed wide industrial usage in the U.S., partly because of their flammability (Patty. Indus

Hyg & Tox, 3rd Ed., Vol. 2A, 2B, 2C, 1981-82). 1,2-dichloroethylene obtained as a byproduct is

used as feed stock for the synthesis of tri- and perchloroethylene (Ullmann’s Encyc Indust Chem,

5th Ed., Vol. A1, 1985-present). It also has miscellaneous uses such as a liquid dry cleaning
58

agent; cleaning agent for printed circuit boards; for food packaging adhesive; and germicidal

fumigant. The extent of these continued uses has not been confirmed (ATSDR, 1996a).

In applications where dichloroethylenes could be used as solvents and for low

temperature extraction processes, they have been replaced with methylene chloride (Ullmann’s

Ency Indus Chem, 5th Ed., 1985-present).

4.2.3 Disposal

1,2-Dichloroethylene is a potential candidate for rotary kiln incineration at a temperature

range of 820 to 1,600°C and residence times of seconds for liquids and gases and hours for

solids; for fluidized bed incineration at a temperature range of 450 to 980°C and residence times

of seconds for liquids and gases, and longer for solids; and for liquid injection incineration at a

temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds (trans-1,2-

dichloroethylene) (USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration). 

This compound should be susceptible to removal from wastewater by air stripping

(USEPA/ORD. 1980. Innovative and Alternative Technology Assessment Manual). 

Incineration is a disposal method, preferably after mixing with another combustible fuel. Care

must be exercised to assure complete combustion to prevent the formation of phosgene. An acid

scrubber is necessary to remove the halo acids produced. The recommendable method is

incineration (Un. Treat Disposal Methods Waste Chem Data Series No. 5, 1985).

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal

practices are subject to significant revision. Prior to implementing land disposal of waste residue

(including waste sludge) consult with environmental regulatory agencies for guidance on

acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996).

4.3 POTENTIAL FOR HUMAN EXPOSURE

4.3.1 Natural Occurrence

No information on natural occurrence of 1,2-dichloroethylene was identified.

4.3.2 Occupational

Occupational potential for exposure is reported in Section 5 and Section 6 for the cis and

trans isomers, respectively.

4.3.3 Environmental

Most of the 1,2-dichloroethylene released into the environment will eventually enter the

groundwater or the atmosphere (ATSDR, 1996a). Releases to the environment are a result of

process and fugitive emissions from production and use as a chemical intermediate; leaching

from landfills; evaporation from wastewater streams, landfills, and solvents; emissions from

heating or combustion PVC and vinyl copolymers; and formation via anaerobic biodegradation

of some chlorinated solvents (ATSDR, 1996a).
59

4.3.3.1 Environmental Releases

Air: Releases of 1,2-dichloroethylene to air are usually the result of emissions from

industrial production and use facilities, contaminated waste disposal sites, and emissions from

pyrolysis/combustion of certain plastic resins. TRI estimates for releases to the air in 1991

totaled 44,782 pounds (>99 percent of total TRI estimated environmental releases) (ATSDR,

1996a).

Water: 1,2-dichloroethylene may be released to surface waters, groundwater, and has

been detected in drinking water. It may be released to surface waters through runoff from

contaminated waste disposal sites, wastewater from industrial sources, and from some POTWs. 

According to TRI estimates for 1993, a total of 28 pounds of 1,2-dichloroethylene (<0.1 percent

of total releases to the environment) were released to water from reporting manufacturing and

processing facilities (ATSDR, 1996a).

1,2-dichloroethylene may be released to groundwater due to leaching from contaminated

waste disposal sites and cracked sewer interceptors carrying industrial waste contaminated with

this chemical. It may also be released to groundwater as a result of anaerobic degradation of

highly chlorinated ethenes (TCE, PCE) and ethanes present in groundwater (ATSDR, 1996a). 

1,2-dichloroethylene’s presence in drinking water may be attributed to raw water source

contamination; however, there is little documentation of direct groundwater contamination.

Other Media: The cis and trans isomers of 1,2-dichloroethylene are released to soil from

disposal of waste contaminated with this chemical. Additionally, they may also be found in

landfills from anaerobic biodegradation of PCE, TCE, 1,1,1-trichloroethane, and 1,1,2,2-

tetrachloroethane (ATSDR, 1996a). TRI estimates for 1993 indicated that no 1,2-

dichloroethylene was released to land from manufacturing and processing facilities (ATSDR,

1996a). Available data are not sufficient to estimate the amount of 1,2-dichloroethylene released

to soil and to sediments.

4.3.3.2 Monitored Environmental Media Levels

Air: 1,2-dichloroethylene has been detected in ambient air samples in various urban

locations throughout the U.S. It has also been detected in the gas from various landfills in the

U.S. Levels found in the ambient air ranged from <0.1 to 2.6 ppb, and levels in the gas from

landfills ranged from 70 ppb (mean) to 75,600 ppb (maximum values; trans isomer) (ATSDR,

1996a). 1,2-dichloroethylene detected in the indoor air of 2 studies were 0.015 ppb and 8.1 ppb,

respectively (ATSDR, 1996a). The data reported in most studies were not isomer-specific. In

the EPA National Ambient Database update, outdoor ambient concentrations of 1,2-

dichloroethylene averaged 0.326 ppb. A median value of 0.037 ppb was also reported. These

reported levels were base on 161 data points (ATSDR, 1996a). According to ATSDR (1996a),

the efficiency of waste treatment plants has improved and loadings to receiving waters have

decreased. But, this decrease has often resulted in increased emissions to the atmosphere as the

volatile constituents are removed through processes such as air stripping (ATSDR, 1996a).
60

Water: Concentrations of 1,2-dichloroethylene found in water reported in ATSDR

(1996a) are described below. These ranges are based on various studies.

C Surface water: not detected - 1,370.5 ppb (maximum value)

C Groundwater: 0.25-0.28 ppb (average value) - 50,000 ppb (maximum value; trans

isomer)

C Drinking water: trace - 64 ppb (maximum value - groundwater source)

C Leachate: 1.4-470 (cis isomer) ppb - 45-800 ppb (average concentration of

leachate; maximum value)

C Aqueous Lagoon: 50 ppb (trans isomer)

C Wastewater at various industries: 1.6 ppb (cis isomer) - 2,265 ppb (trans isomer;

median value)

C Rainwater: 0.230 ppb (1 sample)

A maximum concentration of 33 ppb for cis isomer was found in a shallow unconfirmed aquifer

receiving waste water from metal plating operations. The EPA Contract Laboratory Program

(CLP) data base has reported trans isomer mean concentrations ranging from 5 to 4,000 ppb at 8

of 357 hazardous waste sites.

Other Media: Trans 1,2-dichloroethylene concentrations ranging from 22 to 55 g/L have

been detected in municipal sludge from various treatment throughout the United States (1996a),

while 0.04 ppm (mean value) to 0.05 ppm (maximum value) of 1,2-dichloroethylene were found

in fish tissues from Commencement Bay in Tacoma, Washington (1996a). Monitoring data for

levels of 1,2-dichloroethylene in soil are very limited. The mean concentration range of 5 to

4,000 ppb was reported at 87 of 357 hazardous waste sites (ATSDR, 1996a). However, the trans

isomer was reported in all cases (ATSDR, 1996a). According to ATSDR (1996a), the available

data for 1,2-dichloroethylene in soil are limited to data from hazardous waste site monitoring.

4.3.3.3 Environmental Fate and Transport

4.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released

to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil

column because of the high water solubility and low Koc values of the two isomers. Also, 1,2-

dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a

breakdown product from microbial reductive dehalogenation of the common industrial solvents

trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2-

dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the

formation of vinyl chloride as a degradation product.

Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be

present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging
61

during wet precipitation is expected because of the high solubility of the two isomers. The

predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals. 

Predicted half-lives for this reaction are 3.6 and 8 days for the trans- and cis- isomers,

respectively.

Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to

surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to

sediments and suspended solids are not expected to be significant transport/partitioning

processes. Although biodegradation is not expected to be a significant degradation process, any

1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation.

4.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (Koc)

for cis- and trans-1,2-dichloroethylene, 36 and 49, respectively, indicate that adsorption of the

1,2-dichloroethylene isomers to soil, sediment, and suspended solids is not a significant fate

process. As a consequence, these isomers should show high mobility in soil (HSDB, 1996;

Howard, 1993).

 

Volatilization: The dominant removal mechanism for the dichloroethylene isomers in

surface waters is volatilization. The Henry's Law constants for cis- and trans- dichloroethylene

are 0.00408 and 0.00938, respectively. Based on these values, the estimated half-lives for

volatilization of cis- and trans-dichloroethylene from a model river 1 m deep with a 1 m/sec

current and a 3 m/sec wind speed are 3.1 and 3.0 hours, respectively. Similarly, the volatilization

half-lives from a 1 m deep body of water predicted from laboratory volatilization studies are 5.0

and 6.2 hours, respectively. Because of their high vapor pressures, both isomers are also

expected to readily volatilize from soil surfaces and also from suspended particulate matter in the

atmosphere (HSDB, 1996; Howard, 1993).

Bioconcentration: Bioconcentration factors of 15 and 22 are predicted for cis- and transdichloroethylene, respectively, based on their respective octanol/water partition coefficients. 

Therefore, bioconcentration in aquatic organisms should not be significant and there is little

potential for biomagnification in the food chain (HSDB, 1996; Howard, 1993).

4.3.3.3.3 Transformation and Degradation Processes

Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2-

dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the

order of months); however, one study reported half-lives on the order of days to weeks. Several

studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils

and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation

product (HSDB, 1996; Howard, 1993; Howard et al., 1991).

Photodegradation: In the atmosphere, cis- and trans-1,2-dichloroethylene react with

photochemically produced hydroxyl radicals resulting in half-lives of 8 and 3.6 days,

respectively. The only product positively identified from this reaction is formyl chloride. Photo-
62

oxidation through reaction with ozone is much slower, on the order of months. Because cis- and

trans-1,2-dichloroethylene absorb only a small amount of UV light in the environmentally

significant range, direct photolysis is an insignificant fate process (HSDB, 1996; Howard, 1993;

Howard et al., 1991).

Hydrolysis: The two isomers of 1,2-dichloroethylene contain no hydrolyzable groups

(Howard et al., 1991)

4.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

4.4.1 General U.S. Population

The general population may be exposed to low levels ranging from 0.013 to 0.076 ppb of

1,2-dichloroethylene through inhalation of contaminated air in urban areas (ATSDR, 1996a). 

ATSDR (1996a) calculated the corresponding average daily intake of 1 to 6 μg/day based on an

average air intake of 20 m3

/day. HSDB (1996) has reported the following assumed

concentrations for average daily intake:

Air intake - assume air concentration of 68 ppt (5.4 μg)

Water intake - assume water concentration from contaminated sources of 1.1 ppb

(2.2 μg) when drinking water is contaminated

The general population with potentially the highest exposures are those living near

production/processing facilities, municipal wastewater treatment plant, hazardous waste sites,

and municipal landfills. Potential exposure exists in air downwind of these sites and in the

contaminated drinking water from groundwater down gradient from the sites (ATSDR, 1996a).

Cis-1,2-dichloroethylene has been identified in 146 of the 1,430 current or former EPA

National Priorities List (NPL) hazardous waste sites and trans -1,2-dichloroethylene has been

identified in at least 563 of the current or former NPL sites (ATSDR, 1996a). Although the

number of sites evaluated for this chemical is not known, the frequency of these sites has been

determined and is presented in Figure 4-1.

4.4.2 Occupational Exposure

According to a 1981-1983 NIOSH survey, a statistical estimate of 215 workers in the

U.S. are potentially exposed to 1,2-dichloroethylene (mixture of cis and trans isomers) in the

workplace (ATSDR, 1996a). An estimated 61 workers are potentially exposed to the cis isomer

(ATSDR, 1996a). An estimate for potential occupational exposure to the trans isomer was not

estimated from the survey.
63

Figure 4-1. Frequency of NPL Sites with 1,2-Dichloroethene (Unspecified) Contamination

(Source: ATSDR, 1996a)
64

4.4.3 Consumer Exposure

Readily available data were not found on consumer exposures for 1,2-dichloroethylene.

4.5 CHAPTER SUMMARY

Table 4-1 summarizes the findings of 1,2-dichloroethylene.

Table 4-1. 1,2-Dichloroethylene Summary

Estimates Support

Uses Many solvent applications Well documented

Production No recent information was identified

Releases 44.8 x 103

 lbs/year to air (>99% of total

environmental releases)

TRI (U.S. EPA, 1996) data

Properties/Fate Volatile; insoluble in water; relatively stable

in air; flammable; significant

bioconcentration not expected

Well documented

Media Levels Air: <0.545-14.16 :g/m3

Ambient air: 0.202 :g/m3

Surface water: ND-1,370 ppb

Groundwater: 0.25-0.28 ppb (average value)

Drinking water: trace-64 ppb

ATSDR (1996a)

161 data points, from EPA National

Ambient Database

General Population

Exposure

Inhalation: 1 to 6 ug/d ATSDR (1996a)

Special Population

Exposures

215 workers are potentially exposed Data from early 1980s
65

5.0 CIS-1,2-DICHLOROETHYLENE

5.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

5.1.1 Nomenclature

CAS No.: 156-59-2

Synonyms: 1,2-cis-dichloroethene; cis-dichloroethylene; ethene, 1,2-dichloro-,

ethylene; 1,2-dichloroTrade Names: Acetalyne dichloride

5.1.2 Formula and Molecular Weight

Structural Formula: C2H2Cl2

Molecular Weight: 96.95

5.1.3 Chemical and Physical Properties

Description: Liquid (Merck Index, 11th Ed., 1989); colorless (Tox & Hazard

Indus Chem Safety manual, 1982); Sweetish (Ullmann’s Encyc

Indust Chem, 5th Ed., Vol A1, 1985-present).

Boiling Point: 60.3°C @ 760 mm Hg (CRC Handbook Chem & Physics, 75th

Ed., 1994-1995).

Melting Point: -80.5°C (CRC Handbook Chem & Physics, 75th Ed., 1994-1995).

Density: 1.2837 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed.,

1994-1995).

Spectroscopy Data: Index of refraction: 1.4490 20°C/D; maximum absorption (vapor):

greater than 200 nm (CRC Handbook Chem & Physics, 75th Ed.,

1994-1995). Sadtler reference number: 3645 (IR, Prism) (Weast,

1979). Refractive index: 1.4519 @ 15°C (Flick. Indust Solvents

Handbook, 1985). Mass: 203 (Atlas of Mass Spectral Data)

(Weast, 1985).

Solubility: Water solubility = 0.35 g/100 g @ 25°C (Kirk-Othmer, 4th Ed.,

Vol. 1, 1991-present). Soluble in alcohol, acetone, ether, benzene,

and chloroform (Weast. Hdbk Chem & Phys, 67th Ed., 1986-87).
66

Volatility: Vapor Pressure: 273 mm Hg @ 30°C.

Vapor Density: 3.54 g/l (at bp, 760 mm Hg) (Flick. Indust Solvents

Hdbk, 1985).

Stability: Decomposes slowly on exposure to air, light, and moisture.

Reactivity: May release explosive chloroacetylene by the contact with copper

or copper alloys (1,2-dichloroethylene (ITII. Tox & Hazard Indus

Chem Safety Manual, 1988). Reacts with strong oxidizers (1,2-

dichloroethylene (Sittig. Handbook Toxic Hazard Chem &

Carcinog, 2nd Ed., 1985).

Octanol/Water

Partition Coefficient: log Kow = 1.86 (Hansch. Log P Database, 1987)

5.1.4 Technical Products and Impurities

No data were identified.

5.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

5.2.1 Production

The U.S. production in 1977 was at least 5.0 x 108

 g (captive production) (SRI). More

recent production data were unavailable. No data were identified for import and export volumes.

5.2.2 Uses

Cis-1,2-dichloroethylene is used as a solvent (isomeric mixture) for perfumes, dyes, and

lacquers; solvent (as mixture) for thermoplastics, fats, and phenols; solvent (as mixture) for

camphor and natural rubber; chemical intermediate (as isomeric mixture) for chlorinated

compound; and an agent in retarding fermentation (SRI). It is also used as a solvent in waxes,

resins, and acetylcellulose and used in the extraction of rubber, as a refrigerant, in the

manufacture of pharmaceuticals and artificial pearls and in the extraction of oils and fats from

fish and meat (Sittig. Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985).

Although cis- and trans-isomers of 1,2-dichloroethylene have had use as solvents and

chemical intermediates, neither isomer has developed wide industrial usage in the U.S., partly

because of their flammability (Patty. Indus Hyg & Tox, 3rd Ed., 1981-82). 1,2-dichloroethylenes

obtained as byproducts are used as feed stock for the synthesis of tri- and perchloroethylene

(Ullmann’s Encyc. Indust. Chem., 5th Ed., Vol 1a, 1985-present).
67

In applications where dichloroethylenes could be used as solvents and for low

temperature extraction processes, they have been replaced by methylene chloride (Ullmann’s

Encyc Indust Chem, 5th Ed., Vol A1, 1985-present).

5.2.3 Disposal

1,2-dichloroethylene may be disposed of by atomizing in a suitable combustion chamber

equipped with an appropriate effluent gas cleaning device (NIOSH/OSHA. Occupat Health

Guide Chem Hazards, 1981). Incineration is a disposal method, preferably after mixing with

another combustible fuel. Care must be exercised to assure complete combustion to prevent the

formation of phosgene. An acid scrubber is necessary to remove the halo acids produced (Sittig. 

Handbook Toxic Hazard Chem & Carcinog, 2nd Ed, 1985). This compound should be

susceptible to removal from wastewater by air stripping (USEPA/ORD. 1980. Innovative and

Alternative Technology Assessment Manual).

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal

practices are subject to significant revision. Prior to implementing land disposal of waste residue

(Including waste sludge) consult with environmental regulatory agencies for guidance on

acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996).

5.3 POTENTIAL FOR HUMAN EXPOSURE

5.3.1 Natural Occurrence

Cis-1,2-dichloroethylene is not known to occur naturally.

5.3.2 Occupational 

Occupational exposure to cis-1,2-dichloroethylene is expected to be through dermal

contact with the vapor and liquids and through inhalation of contaminated air at the work place

(HSDB, 1996).

5.3.3 Environmental

5.3.3.1 Environmental Releases

Cis-1,2-dichloroethylene may be released to the environment in emissions and

wastewater during its production and use as a solvent and extract (HSDB, 1996). The cis isomer

is apparently more commonly found than the trans isomer, but is usually mistakenly listed as the

trans isomer. The Michigan Department of Health has reported that it has the capability of

distinguishing between the two isomers and where concentrations are high, they occasionally find

traces of the trans isomer (HSDB, 1996). Under aerobic conditions that may exist in landfills or

sediments, 1,2-dichloroethylenes may be present as breakdown products from reduction

dehalogenation of trichloroethylene and tetrachloroethylene (HSDB, 1996).
68

5.3.3.2 Monitored Environmental Media Levels

According to HSDB (1996), an assessment of the sources of the cis-1,2-dichloroethylene

is complicated because the cis isomer was a priority pollutant, unlike the trans isomer. These

isomers cannot be differentiated using the EPA standard method analysis. Therefore, monitoring

reports have erroneously listed the trans isomer when the cis isomer is present (HSDB, 1996). 

(See Section 4.0 (1,2-Dichloroethylene) for more information on environmental levels.)

Air: For urban/suburban areas in the U.S., reported levels for 669 sites/samples were 68

ppt (median values) and 3,500 ppt (maximum value). Source areas (101 sites/samples) reported

levels were 300 ppt (median) and 6,700 ppt (maximum value) (HSDB, 1996).

Water: Cis-1,2-dichloroethylene was found in Miami drinking water at 16 ppb,

Cincinnati and Philadelphia at 0.1 ppb, but was not found in 7 other drinking waters surveyed

(HSDB, 1996). Raw water from a well in Wisconsin contained 83.3 ppb of this chemical. The

Biscayne Aquifer (near the Miami inactive drum recycling hazardous waste site) that supplies

drinking water to Dade County, Florida, contained 0-26 ppb. Shallow groundwater near the site

had reported levels of 839 and 13.3-17.9 ppb (HSDB, 1996).

Other Media: Data were not available for levels in food, plants, fish, animals, and milk.

5.3.3.3 Environmental Fate and Transport

5.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released

to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil

column because of the high water solubility and low Koc values of the two isomers. Also, 1,2-

dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a

breakdown product from microbial reductive dehalogenation of the common industrial solvents

trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2-

dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the

formation of vinyl chloride as a degradation product.

Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be

present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging

during wet precipitation is expected because of the high solubility of the two isomers. The

predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals. 

Predicted half-lives for this reaction is 8 days for the cis- isomers.

Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to

surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to

sediments and suspended solids are not expected to be significant transport/partitioning
69

processes. Although bio-degradation is not expected to be a significant degradation process, any

1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation.

5.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (Koc)

for cis-1,2-dichloroethylene of 36 indicate that adsorption of the cis-1,2-dichloroethylene isomer

to soil, sediment, and suspended solids is not a significant fate process. As a consequence, these

isomers should show high mobility in soil (HSDB, 1996; Howard, 1993).

 

Volatilization: The dominant removal mechanism for the dichloroethylene isomers in

surface waters is volatilization. The Henry's Law constants for cis-dichloroethylene is 0.00408. 

Based on this value, the estimated half-life for volatilization of cis-dichloroethylene from a

model river 1 m deep with a 1 m/sec current and a 3 m/sec wind speed is 3.1 hours. Similarly,

the volatilization half-life from a 1 m deep body of water predicted from laboratory volatilization

studies is 5.0 hours. Because of its high vapor pressures, this isomer is also expected to readily

volatilize from soil surfaces and also from suspended particulate matter in the atmosphere

(HSDB, 1996; Howard, 1993).

Bioconcentration: Bioconcentration factors of 15 is predicted for cis-dichloroethylene,

based on its respective octanol/water partition coefficient. Therefore, bioconcentration in aquatic

organisms should not be significant and there is little potential for biomagnification in the food

chain (HSDB, 1996; Howard, 1993).

5.3.3.3.3 Transformation and Degradation Processes

Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2-

dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the

order of months); however, one study reported half-lives on the order of days to weeks. Several

studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils

and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation

product (HSDB, 1996; Howard, 1993; Howard et al., 1991).

Photodegradation: In the atmosphere, cis-1,2-dichloroethylene reacts with

photochemically produced hydroxyl radicals resulting in half-life of 8 days. The only product

positive identified from this reaction is formyl chloride. Photo-oxidation through reaction with

ozone is much slower, on the order of months. Because cis-1,2-dichloroethylene absorb only a

small amount of UV light in the environmentally significant range, direct photolysis is an

insignificant fate process (HSDB, 1996; Howard, 1993; Howard et al., 1991).

Hydrolysis: This isomer of 1,2-dichloroethylene contain no hydrolyzable groups

(Howard et al., 1991)
70

5.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

5.4.1 General U.S. Population

The general population is exposed to cis-1,2-dichloroethylene in urban air and from

contaminated drinking water from groundwater sources. For the average daily intake, HSDB

(1996) has reported the following: air intake, assume a concentration of 68 ppt (5.4 μg); water

intake, assume water concentration from contaminated sources of 0.23-2.7 ppb (0.5-5.4 μg) when

drinking water is contaminated (HSDB, 1996).

5.4.2 Occupational Exposure 

Occupational exposure to cis-1,2-dichloroethylene is expected to be through dermal

contact with the vapor and liquids and through inhalation of contaminated air at the work place

(HSDB, 1996). Data for occupational exposures and exposed population estimates were not

found.

5.4.3 Consumer Exposure

Data for consumer exposures were not found.
71

6.0 TRANS-1,2-DICHLOROETHYLENE

6.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

6.1.1 Nomenclature

CAS No.: 156-60-5

Synonyms: Ethylene, 1,2-dichloro-; sym-dichloroethylene

Trade Names: No data

6.1.2 Formula and Molecular Weight

Structural Formula: C2H2Cl2

Molecular Weight: 96.95

6.1.3 Chemical and Physical Properties

Description: Colorless, light liquid; sweetish odor (Ullmann’s Encyc Indust

Chem, 5th Ed., Vol A1, 1985-present).

Boiling Point: 48.0-48.5°C @ 760 mm Hg (Flick. Indust Solvents Hdbk, 1985).

Melting Point: -50°C (Flick. Indust Solvents Hdbk, 1985).

Density: 1.2565 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed,

1994-1995).

Spectroscopy Data: Refractive index: 1.4490 @ 15°C/D (Flick. Indust Solvents Hdbk,

1985), IR: 3646 (Sadtler Research Laboratories Prism Collection);

NMR: 6742 (Sadtler Research Laboratories Spectral Collection);

MASS: 203 (Atlas of Mass Spectral Data) (Weast, 1985).

Solubility: Soluble in alcohol, ether, acetone, benzene, and chloroform

(Weast, 1986-97). Water solubility: 0.63 g/100 g @ 25°C (Flick. 

Indust Solvents Hdbk, 1985).

Volatility: Vapor Pressure: 395 mm Hg at 30°C (Flick. Indust Solvents Hdbk,

1985).

Vapor Density: 3.67 g/l at (bp at 760 mm Hg) (Flick. Indust

Solvents Hdbk, 1985).
72

Stability: Gradually decomposed by air, light, and moisture, forming HCl

(HSDB Scientific Review Panel; HSDB, 1996); potential phosgene

formation (Merck Index, 10th Ed., 1983).

Reactivity: May release explosive chloroacetylene by the contact with copper

or copper alloys (1,2-dichloroethylene) (ITII. Tox & Hazard Indus

Chem Safety Manual, 1988). Reacts with strong oxidizers (Sittig. 

Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). 

Incompatible with alkalies, difluoromethylene dihypofluorite, and

nitrogen tetraoxide (Sax. Danger Props Indus Mater, 6th Ed.,

1984).

Octanol/Water

Partition Coefficient: log Kow = 2.06 (Hansch. Log P Database, 1987).

6.1.4 Technical Products and Impurities

No data were identified.

6.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank during September 1996.

6.2.1 Production

No data concerning U.S. production, import, or export volumes were identified.

6.2.2 Uses

Trans-1,2-dichloroethylene is more widely used in industry than either the cis isomer or

the commercial mixture (HSDB, 1996). It is used as a solvent for waxes, resins, and

acetylcellulose. It is also used in the extraction of rubber, as a refrigerant, in the manufacture of

pharmaceuticals and artificial pearls and in the extraction of oils and fats from fish and meat

(Sittig. Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). 1,2-dichloroethylenes

obtained as byproducts are used as feed stock for the synthesis of tri- and perchloroethylene. In

applications where dichloroethylenes could be used as solvents and for low temperature

extraction processes, they have been replaced by methylene chloride (Ullmann’s Encyc Indust

Chem, 5th Ed., Vol. A1, 1985-present). Although this chemical has had use as a solvent and

chemical intermediate, it has not developed wide industrial usage in the U.S., partly because of

its flammability (Patty. Indus Hyg and Tox, 3rd Ed., Vol. 2A, 1981-82).
73

6.2.3 Disposal

A method of disposal is incineration, preferably after mixing with another combustible

fuel. Care must be exercised to assure complete combustion to prevent the formation of

phosgene. An acid scrubber is necessary to remove the halo acids produced (Sittig. Handbook

Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). Trans-1,2-dichloroethylene is a potential

candidate for rotary kiln incineration at a temperature range of 820 to 1,600°C and residence

times of seconds for liquids and gases and hours for solids. It is also a potential candidate for

fluidized bed incineration at a temperature range of 450 to 980°C and residence times of seconds

for liquids and gases, and longer for solids and a potential candidate for liquid injection

incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds

(USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration). This compound

should be susceptible to removal from wastewater by air stripping (USEPA/ORD. 1980. 

Innovative and Alternative Technology Assessment Manual).

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal

practices are subject to significant revision. Prior to implementing land disposal of waste residue

(Including waste sludge) consult with environmental regulatory agencies for guidance on

acceptable disposal practices (HSDB Scientific Review Panel, HSDB, 1996).

6.3 POTENTIAL FOR HUMAN EXPOSURE

6.3.1 Natural Occurrence

Trans-1,2-dichloroethylene is not known to occur naturally.

6.3.2 Occupational

Potential occupational exposures exist in production and manufacturing facilities from

the use of trans-1,2-dichloroethylene as a solvent and extractant.

6.3.3 Environmental

6.3.3.1 Environmental Releases

Trans-1,2-dichloroethylene may be released to the environment in air emissions and

wastewater during its production and use. Dichloroethylenes can be found as breakdown

products from the reduction dehalogenation of common industrial solvents such as

trichloroethylene, tetrachloroethylene, and 1,1,2,2-tetrachloroethane under aerobic high organic

mix conditions, that may exist in landfills, aquifers, or sediment. The cis isomer is the isomer

found most. However, it mistakenly reported as the trans isomer because EPA standard methods

analytical procedures do not distinguish between isomers (HSDB, 1996). See Section 4.0 (1,2-

Dichloroethylene) for more information on environmental levels.

Air: Trans-1,2-dichloroethylene has been identified in ambient air near production and

manufacturing facilities from its use.
74

Water: Trans-1,2-dichloroethylene has been detected in drinking water, surface water,

and groundwater.

Other Media: Trans-1,2-dichloroethylene has been identified in the effluent of many

manufacturing facilities, POTW effluents (and sludges), urban runoff, and sediment and soil

samples (HSDB, 1996).

6.3.3.2 Monitored Environmental Media Levels

Air: The atmospheric concentration near source areas in Edison, New Jersey, was 930 ppt

(HSDB, 1996).

Water: Trans-1,2-dichloroethylene was found in drinking water in Miami at 1 PPB; in

private wells in Illinois at nondetected to 64 ppb with a median of 8 ppb (HSDB, 1996). It was

found in a groundwater plume of predominantly trichloroethylene that was believed to originate

from an old industrial source. In Tacoma, Washington, two utility production wells had levels of

200 ppb trans-1,2-dichloroethylene. Groundwater monitoring wells (789 wells) near a

degreasing plant in Connecticut contained levels of this chemical ranging from 1.2 - 320.9 ppb

(HSDB, 1996).

Other Media: In an EPA survey of wastewater from 4,000 industrial and publicly owned

treatment works, the highest effluent concentration among several industries was for iron and

steel manufacturing at 3,013 ppb, with a median contamination of 2,265.9 ppb. Median

concentrations in the effluents of other industries were: organics and plastics (14.6 ppb);

inorganic chemicals (3.9 ppb); rubber processing (19.0 ppb); auto and other laundries (60.6 ppb);

explosives (3.9 ppb); electronics (140.7 ppb); mechanical products (13.7 ppb); transportation

equipment (29.3 ppb); POTWs (16.3 ppb) (Shackelford et al., Analyt Chem Acta, Vol. 146,

1983; HSDB, 1996). In another survey of industrial occurrences, wastewater discharges had the

following mean concentrations: metal finishing (260 ppb); photographic equipment (2,200 ppb

maximum concentration); nonferrous metal manufacturing (75 ppb); rubber processing (150

ppb).

6.3.3.3 Environmental Fate and Transport

6.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released

to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil

column because of the high water solubility and low Koc values of the two isomers. Also, 1,2-

dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a

breakdown product from microbial reductive dehalogenation of the common industrial solvents

trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2-
75

dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the

formation of vinyl chloride as a degradation product.

Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be

present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging

during wet precipitation is expected because of the high solubility of the two isomers. The

predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals. 

Predicted half-lives for this reaction is 3.6 days for the trans- isomers.

Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to

surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to

sediments and suspended solids are not expected to be significant transport/partitioning

processes. Although biodegradation is not expected to be a significant degradation process, any

1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation.

6.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (Koc)

for trans-1,2-dichloroethylene, 49, indicate that adsorption of this 1,2-dichloroethylene isomer to

soil, sediment, and suspended solids is not a significant fate process. As a consequence, this

isomer should show high mobility in soil (HSDB, 1996; Howard, 1993).

 

Volatilization: The dominant removal mechanism for the dichloroethylene isomers in

surface waters is volatilization. The Henry's Law constants for trans-dichloroethylene is 0.00938. 

Based on this value, the estimated half-life for volatilization of trans-dichloroethylene from a

model river 1 m deep with a 1 m/sec current and a 3 m/sec wind speed is 3.0 hours. Similarly,

the volatilization half-life from a 1 m deep body of water predicted from laboratory volatilization

studies is 6.2 hours. Because of its high vapor pressure, this isomer is also expected to readily

volatilize from soil surfaces and also from suspended particulate matter in the atmosphere

(HSDB, 1996; Howard, 1993).

Bioconcentration: Bioconcentration factors of 15 and 22 are predicted for cis- and transdichloroethylene, respectively, based on their respective octanol/water partition coefficients. 

Therefore, bioconcentration in aquatic organisms should not be significant and there is little

potential for biomagnification in the food chain (HSDB, 1996; Howard, 1993).

6.3.3.3.3 Transformation and Degradation Processes

Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2-

dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the

order of months); however, one study reported half-lives on the order of days to weeks. Several

studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils

and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation

product (HSDB, 1996; Howard, 1993; Howard et al., 1991).
76

Photodegradation: In the atmosphere, trans-1,2-dichloroethylene react with

photochemically produced hydroxyl radicals resulting in a half-life of 3.6 days. The only product

positive identified from this reaction is formyl chloride. Photo-oxidation through reaction with

ozone is much slower, on the order of months. Because trans-1,2-dichloroethylene absorb only a

small amount of UV light in the environmentally significant range, direct photolysis is an

insignificant fate process (HSDB, 1996; Howard, 1993; Howard et al., 1991).

Hydrolysis: Trans-1,2-dichloroethylene contains no hydrolyzable groups (Howard et al.,

1991)

6.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

6.4.1 General U.S. Population

The general population is exposed to trans-1,2-dichloroethylene in urban air and

contaminated drinking water from ground water sources.

6.4.2 Occupational Exposure

Occupational exposure will be through dermal contact with the vapor and liquid or

through inhalation. Data for occupational exposures and exposed population estimates were not

found.

6.4.3 Consumer Exposure

Data for consumer exposures were not found.
77

7.0 1,1,1,2-TETRACHLOROETHANE

7.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

7.1.1 Nomenclature

CAS No.: 630-20-6

Synonyms: Ethane, 1,1,1,2-tetrachloroTrade Names: NCI-C52459

7.1.2 Formula and Molecular Weight

Structural Formula: C2H2Cl4

Molecular Weight: 167.85

7.1.3 Chemical and Physical Properties

Description: Yellowish-red liquid (NIOSH Pocket Guide Chem Haz, 1994).

Boiling Point: 130.5°C @ 760 mm Hg (CRC Handbook Chem & Physics, 75th

Ed., 1994-1995).

Melting Point: -70.2°C (CRC Handbook Chem & Physics, 75th Ed., 1994-1995).

Density: 1.4506 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed.,

1994-1995).

Spectroscopy Data: Index of Refraction: 1.4821 @ 20°C/D (Weast, 1986-87); Mass:

1074 (Atlas of Mass Spectral Data) (Weast, 1985).

Solubility: Water solubility is 1.1 x 103

 mg/l @ 25°C (McKay and Shiu, 1981;

J. Phys. Chem. Ref. Data, Vol. 19). Soluble in alcohol, ether,

acetone, benzene, chloroform (Weast, 1986-87).

Volatility: Vapor Pressure - 14 Torr at 25°C (Willing, WL. 1977. Environ Sci

Technol, Vol. 11).

Vapor Density - No data.

Stability: Decomposes when heated and emits toxic fumes of chlorine (Sax,

6th Ed., 1984); when in contact with flame, incandescent material,
78

or red hot metal surfaces, it decomposes to form hydrochloric acid,

carbon monoxide, and carbon dioxide (Encyc. Occupat. Health and

Safety, 1983).

Reactivity: Mixtures of sodium-potassium alloy and bromoform,

tetrachloroethane, or pentachloroethane can explode on standing at

room temperature. They are especially sensitive to impact (NFPA. 

1986. Fire Protect Guide Hazard Matls, 9th Ed.) Reacts with

dinitrogen tetraoxide; potassium hydroxide nitrogen tetroxide; 2,4-

dinitrophenyl disulfide (NIOSH Pocket Guide Chem Haz, 1994).

Octanol/Water

Partition Coefficient: Log Kow = 2.66 (IARC Monographs, 1972-present)

7.1.4 Technical Products and Impurities

1,1,1,2-tetrachloroethane is available at 99% purity and is used for a laboratory standard

for selected EPA methods (The Aldrich Catalog/Handbook of Fine Chemicals, 1994-95). It is

not available in commercial quantities.

7.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

7.2.1 Production

As of 1982, this chemical was not produced commercially in USA; no data are available

for other years. This chemical is not produced on an industrial scale and is mainly the byproduct

from the production of chlorinated ethanes. No data are available concerning import and export

volumes.

7.2.2 Uses

1,1,1,2-tetrachloroethane is used as a solvent in cleaning, degreasing, and extraction

processes; in manufacture of insecticides, herbicides, soil fumigants, bleaches, paints and

varnishes and as a laboratory reagent (NRC. 1977. Drinking Water & Health; IARC

Monograph, V.41, 1986). 1,1,1,2-tetrachloroethane is used primarily as a feedstock for the

production of solvents such as trichloroethylene and tetrachloroethylene (Kirk-Othmer. 1991-

present. Encyc Chem Tech, 4th Ed., Vol 1).
79

7.2.3 Disposal

1,1,1,2-tetrachloroethane is a potential candidate for fluidized bed incineration at a

temperature range of 450 to 980°C and residence times of seconds for liquids and gases and

longer for solids; for rotary kiln incineration at a temperature range of 820 to 1,600°C and

residence times of seconds for liquids and gases and hours for solids; and for liquid injection

incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds

(USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration. EPA 68-03-3025). 

Incineration is a method of disposal, preferably after mixing with another combustible fuel. Care

must be exercised to assure complete combustion to prevent the formation of phosgene. An acid

scrubber is necessary to remove the halo acids produced. Recommendable methods are

incineration and evaporation. Not recommendable method: discharge to sewer.

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal

practices are subject to significant revision. Prior to implementing land disposal of waste residue

(including waste sludge), consult with environmental regulatory agencies for guidance on

acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996).

7.3 POTENTIAL FOR HUMAN EXPOSURE

7.3.1 Natural Occurrence

Available data do not indicate that 1,1,1,2-tetrachloroethane occurs naturally.

7.3.2 Occupational

1,1,1,2-tetrachloroethane is not produced on an industrial scale but is formed as an

incidental byproduct. Potential occupational exposure would occur from exposure to air

emissions or contact with the vapor or liquid in the workplace.

7.3.3 Environmental

7.3.3.1 Environmental Releases

According to available data, it appears that 1,1,1,2-tetrachloroethane is currently not

produced in the U.S. However, since the chemical may be formed incidentally during the

manufacture of other chlorinated ethanes, it may be released into the environment as air

emissions or in wastewater (HSDB, 1996). It has not been confirmed if this chemical is currently

used in the U.S. However, if used, environmental releases as a result of use would be expected.

7.3.3.2 Monitored Environmental Media Levels

Air: Field studies were conducted in Arizona and California to better characterize the

abundance of selected chemicals in the atmosphere. Average daily dosages from exposure to

haloethane, including 1,1,1,2-tetrachloroethane, was determined to be 142 μg/day (Singh, H.B. et

al., 1981; Atmos. Environ. Vol. 15, No. 4; HSDB, 1996). 1,1,1,2-tetrachloroethane was not
80

detected in two rural/remote sites in the U.S. For 602 urban/suburban sites in the U.S., a median

level of 2.2 ppt and a maximum level of 63 ppt were found. In source areas, 43 sites/samples in

the U.S., the mean concentration was 0.071 ppt and the maximum level 3.1 ppt. However,

1,1,1,2-tetrachloroethane was not detected in over 75 percent of the samples (Brodzinsky and

Singh, SRI Contract 68-02-34; Class and Ballschmiter, 1986, Chemosphere, Vol. 15; HSDB,

1996).

Water: In the U.S. Groundwater Supply Survey, 1,1,1,2-tetrachloroethane was not

detected (detection limit 0.2 ppb) in the drinking water of 945 supplies where groundwater was

the source (Westrick et al., 1984; J. Amer. Water Works Assoc., Vol. 76; HSDB, 1996).

Other Media: Wastewater was analyzed in a survey conducted by the EPA of 4,000

industrial and publicly owned treatment works. 1,1,1,2-tetrachloroethane was identified in the

discharges from several industrial categories. The median concentrations reported as follows: 

organics and plastic (27.4 ppb); inorganic chemicals (14.8 ppb); and electronics (272.6 ppb)

(Shackelford, W.M. et al., 1983, Analyt. Chem. Acta., Vol. 146; HSDB, 1996).

7.3.3.3 Environmental Fate and Transport

7.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of 1,1,1,2-tetrachloroethane

released to surface soils is volatilization. Because of its moderate mobility in soils,

tetrachloroethylene introduced into soil (e.g., landfills) has the potential to migrate through the

soil into groundwater.

Fate in the Atmosphere: In the atmosphere, 1,1,1,2-tetrachloroethane is expected to be

present primarily in the vapor phase rather than sorbed to particulates because of its moderate

vapor pressure. Removal by scavenging during wet precipitation is expected because of the

moderate solubility of 1,1,1,2-tetrachloroethane in water (1,100 mg/L). The major degradation

process affecting vapor phase 1,1,1,2-tetrachloroethane is photo-oxidation by hydroxyl radicals

and the chlorine radicals formed by the hydroxyl radical reaction (half-life on the order of years). 

Due to its persistence, 1,1,1,2-tetrachloroethane will disperse over long distances and slowly

diffuse into the stratosphere where it would be rapidly degraded.

Fate in Aquatic Environments: The dominant fate of 1,1,1,2-tetrachloroethane released

to surface waters is volatilization (predicted half-life of hours). Bioconcentration and sorption to

sediments and suspended solids are not expected to be significant transport/partitioning

processes.
81

7.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: A Koc of 93 is predicted for 1,1,1,2-tetrachloroethane based

on its measured water solubility. An experimentally determined Koc for 1,1,1,2-tetrachloroethane

is reported to be 399. Based on the predicted and measured Kocs, 1,1,1,2-tetrachloroethane is

expected to exhibit moderate mobility and may leach slowly to the groundwater particularly in

soils with low organic content (HSDB, 1996).

 

Volatilization: The dominant removal mechanism for 1,1,1,2-tetrachloroethane in

surface waters is volatilization. The half-life will depend on wind and mixing conditions and is

estimated to range from 4 to 11 hours in rivers, lakes, and ponds based on laboratory

experiments. Because of its moderate vapor pressure (14 torr at 25 degrees C) and relatively low

soil adsorption coefficient (Koc of 93 to 399), 1,1,1,2-tetrachloroethane is expected to volatilize

from dry soil surfaces and also from suspended particulate matter in the atmosphere (HSDB,

1996).

Bioconcentration: No experimental data are available on the bioconcentration of 1,1,1,2-

tetrachloroethane. A bioconcentration factor of 12 is predicted for 1,1,1,2-tetrachloroethane

based on its measured water solubility of 1,100 mg/L. Actual BCFs measured in fish studies are

less than 10 for structurally similar halogenated aliphatic compounds. Therefore,

bioconcentration in aquatic organisms should not be significant and there is little potential for

biomagnification in the food chain (HSDB, 1996).

7.3.3.3.3 Transformation and Degradation Processes

Biodegradation: Little information is available on the biodegradability of 1,1,1,2-

tetrachloroethane. Based on the results of a river die-away test for 1,1,1,2-tetrachloroethane and

several studies examining the biodegradability of 1,1,1-trichloroethane, 1,1,1,2-tetrachloroethane

is estimated to undergo biodegradation at a slow rate. The estimated half-lives are one to six

months under aerobic conditions and 4 to six months under anaerobic conditions (Howard et al.,

1991).

Photodegradation: Based upon an estimated rate constant for the vapor phase photooxidation reaction with photochemically produced hydroxyl radicals, the half-life of 1,1,1,2-

tetrachloroethane in the atmosphere is 550 days. No data are readily available on the photolysis

of 1,1,1,2-tetrachloroethane (HSDB, 1996).

Hydrolysis: Hydrolysis of 1,1,1,2-tetrachloroethane is not significant at environmental

temperatures and pHs; the half-life for this process (at 25 C, pH 7) is 46.8 years (HSDB, 1996).

7.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

7.4.1 General U.S. Population

Potential exposure, if any, to the general population would probably be through inhalation

of ambient air contaminated with 1,1,1,2-tetrachloroethane (HSDB, 1996).
82

7.4.2 Occupational Exposure

Data are not available for the estimated occupationally exposed populations.

7.4.3 Consumer Exposure

According to Kirk-Othmer (1991), 1,1,1,2-tetrachloroethane is used primarily as a

feedstock for the production of solvents such as trichloroethylene and tetrachloroethylene

(HSDB, 1996). The IARC Monographs in 1986 have reported use in the manufacture of

products such as paints and varnishes. It has not been confirmed if this use is current or if these

products are/were consumer or industrial products (HSDB, 1996).

7.5 CHAPTER SUMMARY

Table 7-1 summarizes the findings of 1,1,1,2-tetrachloroethane.

Table 7-1. 1,1,1,2-Tetrachloroethane Summary

Estimates Support

Uses Many solvent applications; chemical

intermediate

Recent information

Production As of 1982, not produced in U.S.; no other

data are available

Releases No available data

Properties/Fate Volatile; water soluble; no significant

bioconcentration; moderate mobility

Recent information

Media Levels Air: 0.012 :g/m3

 - median value at

602 urban/suburban sites

Water: Non detect (detection limit = 0.2

ppb) in 945 groundwater supplies

General Population

Exposure

No available data

Special Population

Exposures

No available data
83

8.0 1,1-DICHLOROETHANE

8.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

8.1.1 Nomenclature

CAS No.: 75-34-3

Synonyms: Ethane, 1,1-dichloro-; ethylidene chloride; ethylidene dichloride

Trade Names: NCI-C04535

8.1.2 Formula and Molecular Weight

Molecular Formula: C2H4Cl2

Molecular Weight: 98.97

8.1.3 Chemical and Physical Properties

Description: Oily liquid, chloroform-like odor, taste as of chloroform

(Merck Index, 11th Ed., 1989); colorless liquid (Sax. Danger

Props Idus Mater, 6th Ed., 1984); colorless, oily liquid,

chloroform-like odor (NIOSH Pocket Guide Chem Haz, 1994);

aromatic ethereal odor (Sax. Hawley’s Condensed Chem Dict,

11th Ed., 1987).

Boiling Point: 57.3°C (Merck Index, 11th Ed., 1989).

Melting Point: -96.9°C (CRC Handbook Chem & Physics, 75th Ed., 1994-

1195).

Density: 1.175 @ 20°C/4°C (Merck Index, 11th Ed., 1989).

Spectroscopy Data: Index of Refraction: 1.4167 @ 20°C (Merck Index, 11th Ed.,

1989); Sadtler Reference Number: 3205 (IR, prism); J118

(NMR) (Weast, 1979); Mass: 68 (National Bureau of Standards

EPA-NIH Mass Spectra Data Base) (Weast, 1985).

Solubility: 0.55 g/100 ml water at 20°C; soluble in ethanol, ethyl ether

(Patty. Indus Hyg & Tox, 3rd Ed., Vol 2A, 2B, 2C, 1981-82)

Volatility: Vapor Pressure: 3.44 (air = 1) (Sax. Danger Props Indus

Mater, 6th Ed., 1984).
84

Vapor Density: 234 torr at 25°C (Patty. Indus Hyg & Tox, 3rd

Ed., Vol 2A, 2B, 3C, 1981-82).

Stability: No data.

Reactivity: Reacts with strong oxidizers, strong caustics (NIOSH Pocket

Guide Chem Haz, 1994).

Octanol/Water

Partition Coefficient: Log Kow = 1.9 (ITC/USEPA. Information Review #209

(Draft) Chloroethanes, 1980).

8.1.4 Technical Products and Impurities

1,1-dichloroethane is produced as reagent grade, 99.7% pure, with the following

impurities: ethyl chloride 0.02%, butylene oxide 0.08%, trichloroethylene 0.08%, ethylene

dichloride 0.01%, unknown 0.14% (expressed as volume percentage by weight of sample

(ITC/USEPA. 1980. Information Review #209).

8.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

8.2.1 Production

No information was identified for U.S. production, import, or export volumes.

8.2.2 Uses

1,1-dichloroethane is used as a solvent for plastics, oils, and fats; cleaning agent;

degreaser; in rubber cementing; as a fumigant and insecticide spray; in fabric spreading; in fire

extinguishing; and in medication: formerly used as an anesthetic (Browning. 1965. Tox &

Metab Indus Solv). It is also used as an extractant for heat-sensitive substances (NIOSH OSHA. 

1981. Occupat Health Guide Chem Hazards). Other uses include as a coupling agent in

antiknock gasoline; in paint, varnish and paint removers; metal degreasing; and in ore flotation

(Verschueren. 1983. Handbook Environ Data Org Chem). 1,1-dichloroethane is usually used as

an intermediate in the production of 1,1,1-trichloroethane by thermal chlorination or

photochlorination and in the production of vinyl chloride (Kirk-Othmer, 1991-present).

8.2.3 Disposal

Generators of waste containing this contaminant (i.e., EPA hazardous waste number

U076) must conform with USEPA regulations in storage, transportation, treatment, and disposal

of waste (40 CFR 240-280, 300-306, 702-799). 1,1-dichloroethane may be disposed of by

atomizing in a suitable combustion chamber equipped with an appropriate effluent gas cleaning
85

device (NIOSH OSHA. 1981. Occupat Health Guide Chem Hazards). It is a potential candidate

for liquid injection incineration, with a temperature range of 650 to 1,600°C and a residence time

of 0.1 to 2 seconds; for rotary kiln incineration, with a temperature range of 820 to 1,600 °C and

a residence time of seconds; and for fluidized bed incineration, with a temperature range of 450

to 980°C and a residence time of seconds (USEPA. 1981. Engineering Handbook for Hazardous

Waste Incineration). The following wastewater treatment technologies have been investigated

for 1,1-dichloroethane: concentration process: stripping, solvent extraction, activated carbon,

and resin adsorption (USEPA. 1982. Management of Hazardous Waste Leachate. EPA

Contract No. 68-03-2766).

8.3 POTENTIAL FOR HUMAN EXPOSURE

8.3.1 Natural Occurrence

There are no known natural sources of 1,1-dichloroethane; however, it has been reported

that 1,1,1-trichloroethane is biodegraded to 1,1-dichloroethane in anaerobic environments such as

landfills (ATSDR, 1990).

8.3.2 Occupational

In addition to members of the general populations living near emission point sources and

hazardous waste sites, human exposure to 1,1-dichloroethane is expected to be highest among

certain occupational groups (ATSDR, 1990). These groups are workers in the chemical and

allied products industry (ATSDR, 1990).

8.3.3 Environmental

8.3.3.1 Environmental Releases

The primary disposition of 1,1-dichloroethane in the environment is the result of

production, storage, consumption, transport, and disposal from its use as chemical intermediate,

solvent, finish remover, and degreaser (ATSDR, 1990). Releases from industrial processes are

almost exclusively to the atmosphere. 1,1-dichloroethane has been detected generally at low

levels in ambient air, surface water, groundwater, drinking water, and human breath. 

Concentrations are largest in environmental media near source areas (ATSDR, 1990). Another

source of this chemical in the environment is the reduction (biotic or abiotic) of 1,1,1-

trichloroethane to 1,1-dichloroethane in groundwater (HSDB, 1996).

Air: The majority (99 percent) of all releases of 1,1-dichloroethane to the environment

are emissions to the atmosphere (ATSDR, 1990). Releases from the production of 1,1,1-

trichloroethane and 1,2-dichloroethane account for approximately 52 percent and 35 percent,

respectively of these releases (ATSDR, 1990). Approximately 52,000 kg of 1,1-dichloroethane

are released to the air from POTWs (ATSDR, 1990).

Water: Releases of 1,1-dichloroethane to surface waters from industrial solvent use and

from POTWs are approximately 2,000 kg/yr (ATSDR, 1990). The largest sources of these
86

releases are believed to be from its use as a cleaning solvent or chemical intermediate and from

POTWs (ATSDR, 1990). Approximately 1,000 kg/yr of 1,1-dichloroethane are released in the

effluents of POTWs (ATSDR, 1990).

Other Media: Releases to land from solvent use and POTWs were estimated at 6,000 kg

in 1978 (ATSDR, 1990). According to ATSDR (1990), approximately 4,000 kg/yr of 1,1-

dichloroethane are released to land as sludge from POTWs.

8.3.3.2 Monitored Environmental Media Levels

Air: Atmospheric levels of 1,1-dichloroethane have been detected at urban, rural, and

industrial sites across the U.S. The reported median concentration is 55 ppt (ATSDR, 1990). In

the urban/suburban parts of the U.S., reported concentrations were 61 ppt (median value) and 100

ppt (maximum values) for the analysis of 455 samples (HSDB, 1996). The concentrations in

source areas (101 samples) were 11 ppt (median value) and 1,400 ppt (maximum value) (HSDB,

1996).

Water: Data summarized from the EPA STORET data base in 1982 have shown

concentrations for 1,1-dichloroethane ranging from <10 ppb (not detected) to 1,900 ppb

(ATSDR, 1990). The highest reading was from the upper Mississippi River Basin; however, the

reported monitoring results indicated that in surface water the levels were mostly <10 ppb.

According to a study summarizing groundwater data from numerous State agencies, 18

percent of monitored drinking water wells contained 1,1-dichloroethane; the highest reported

concentration in wells was 11,300 ppb and a maximum surface concentration of 0.2 ppb

(ATSDR, 1990; HSDB, 1996). In Iowa, 127 wells from 58 public water supplies contained 1,2-

dichloroethane residues 1 to 24 ppb (HSDB, 1996).

Finished water supplies in the U.S. from groundwater sources that were tested for EPA

contaminants had a maximum concentration of 4.2 ppb; detectable levels of 1,1-dichloroethane

was found in 10.8 percent of 158 non-random samples. Groundwater samples taken from 178

hazardous waste disposal sites contained an average concentration of 0.31 ppm with a maximum

concentration of 56.1 ppm and had a frequency of 18 percent (ATSDR, 1990).

Other Media: Data for levels in soil were not found. The reported mean concentration

was 33 ppt for oysters obtained from the Mississippi River delta (HSDB, 1996). Information

were not found for ambient concentrations of 1,1-dichloroethane in soil, current disposal of

waste products containing this chemical in landfills, foods, plants, fish, or animals (HSDB, 1996;

ATSDR, 1990).
87

8.3.3.3 Environmental Fate and Transport

8.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport sections.

Fate in Terrestrial Environments: The dominant fate of 1,1-dichloroethane released to

surface soils is volatilization. Because of its high mobility in soils, 1,1-dichloroethane

introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater. 

Biodegradation under anaerobic conditions in soil and groundwater may occur at a relatively

slow rate (half-lives on the order of months or longer).

Fate in the Atmosphere: In the atmosphere, 1,1-dichloroethane is expected to be present

in the vapor phase rather than sorbed to particulate matter. Removal of 1,1-dichloroethane

during wet precipitation is expected because of its relatively high water solubility. 1,1-

Dichloroethane will degrade by reaction with photochemically produced hydroxyl radicals. 

Because photo-oxidation is not a rapid process (predicted half-lives ranging from 10 to 100

days), considerable dispersion of 1,1-dichloroethane in the atmosphere may occur.

Fate in Aquatic Environments: The dominant fate of 1,1-dichloroethane released to

surface waters is volatilization (predicted half-life of 1 to 10 days). Bioconcentration,

biodegradation, and sorption to sediments and suspended solids are not expected to be significant

fate processes.

8.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: The very low predicted soil adsorption coefficients (Koc) for

1,1-dichloroethane (Koc of 43) indicates that sorption of 1,1-dichloroethane to soil, sediment, and

suspended solids is not a significant fate process. As a consequence, these isomers should show

high mobility in soil (HSDB, 1996).

 

Volatilization: The dominant removal mechanism for the 1,1-dichloroethane isomers in

surface waters is volatilization. The half-life will depend on wind and mixing conditions and is

estimated to range from 1 to 10 days in rivers, lakes, and ponds based on laboratory experiments. 

Because of its high vapor pressure and relatively low soil adsorption coefficient, 1,1-

dichloroethane is expected to volatilize rapidly from soil surfaces and also from suspended

particulate matter in the atmosphere (HSDB, 1996).

Bioconcentration: A bioconcentration factor of 1.3 is predicted for 1,1-dichloroethane

based on the reported water solubility of 5,500 mg/L. Therefore, bioconcentration in aquatic

organisms should not be significant and there is little potential for biomagnification in the food

chain (HSDB, 1996).
88

8.3.3.3.3 Transformation and Degradation Processes

Biodegradation: The results of aerobic biodegradation studies indicate that 1,1-

dichloroethane is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the order

of months). Although no studies examining the anaerobic biodegradation of 1,1-dichloroethane

are available, the estimated half-life under anaerobic conditions has been estimated to range from

months to years (HSDB, 1996; Howard et al., 1991).

Photodegradation: Based on measured rate data for the vapor phase reaction with

hydroxyl radicals, the estimated half-life of 1,1-dichloroethane in the troposphere ranges from 10

to 100 days (HSDB, 1996; Howard et al., 1991).

Hydrolysis: No information specifically addressing the hydrolytic half-life of 1,1-

dichloroethane is available. Considering the volatility of 1,1-dichloroethane from water and the

fact that the hydrolytic half-lives of structurally similar chlorinated ethanes are on the order of

months to years, indicates that hydrolysis is not an important fate process (HSDB, 1996; Howard

et al., 1991).

8.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

8.4.1 General U.S. Population

The primary route of exposure for the general population to 1,1-dichloroethane is the

inhalation of air contaminated with this chemical. An additional potential route of exposure is

ingestion of 1,1-dichloroethane contaminated drinking water. Specifically, persons near

industrial facilities and hazardous waste may be potentially exposed from inhalation of ambient

air and ingestion of drinking water (ATSDR, 1990). EPA has identified 1,1-dichloroethane in

248 of the 1,177 NPL sites; the number of sites evaluated for this chemical was not reported

(ATSDR, 1990). The frequency of these sites within the U.S. are presented in Figure 8-1.

The U.S. EPA assumed median ambient air concentration of 55 ppt and an average

inhalation rate of 20 m3/day and estimated the average inhalation exposure to 1,1-dichloroethane

from the general population to be 4 μg/day (ATSDR, 1990).

8.4.2 Occupational Exposure

Populations potentially exposed in the workplace in the early 1980s were estimated by

NIOSH to have ranged from 715 to 1,957 workers (ATSDR, 1990). Occupational exposures are

primarily the result of the use of 1,1-dichloroethane as a chemical intermediate, solvent, and a

component of fumigant formulations (ATSDR, 1990).

8.4.3 Consumer Exposure

No data were found for consumer exposure estimates.
89

Figure 8-1. Frequency of NPL Sites with 1,1-Dichloroethane Contamination (Source: ATSDR,

1990)
90

8.5 CHAPTER SUMMARY

Table 8-1 summarizes the findings of 1,1-dichloroethane.

Table 8-1. 1,1-Dichloroethane Summary

Estimates Support

Uses Many solvent uses; fumigant; chemical

intermediate; degreaser

Well documented

Production No available information

Releases Predominantly air - 52,000 kg released to air

from POTWs

ATSDR (1990)

Properties/Fate Volatile; slightly soluble in water; no

significant bioconcentration or

biodegradation expected

Media Levels Air: urban/suburban - 0.332 :g/m3

(median)

Water: surface water <10 ppb to 1,900 ppb

Groundwater: varies

1 to 24 ppb (Iowa; 127 wells)

455 samples

General Population

Exposure

Primarily through air or potentially

contaminated groundwater

Air = 4 :g/d

ATSDR (1990)

Special Population

Exposures

Chemical and allied product workers ATSDR (1990)
91

SECTION C. METABOLITES OF TRICHLOROETHYLENE AND PARENT

COMPOUNDS

9.0 CHLORAL

9.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC

(1995).

9.1.1 Nomenclature

CAS No.: 75-87-6

Synonyms: 2,2,2-trichloroacetaldehyde; acetaldehyde, trichloro-; anhydrous

chloral; trichloroacetaldehyde; trichloroethanol

Trade Name: Grasex

9.1.2 Formula and Molecular Weight

Structural Formula: C2HCl3-0

Molecular Weight: 147.40

9.1.3 Chemical and Physical Properties

Description: Colorless, oily liquid with an irritating odor (Encyc. Occupat.

Health & Safety, 1983).

Boiling Point: 97.8°C @ 760 mm Hg (Merck Index, 10th Ed., 1983).

Melting Point: -57.5°C (Merck Index, 10th Ed., 1983).

Density: 1.5121 @ 20°C/4°C (Weast. Hdbk. Chem. & Phys., 67th Ed., 

 1986-87).

Spectroscopy Data: Index of refraction: 1.45572 @ 20°C/D (Weast. Hdbk. Chem. &

Phys., 67th Ed., 1986-87); IR: 4626, IR: 4426 (Sadtler Research

Laboratories Prism Collection); IR: 6507 (Coblentz Society

Spectral Collection); UV: 5-3 (Organic Electronic Spectral

Data); Mass: 814 (Atlas of Mass Spectral Data) (Weast. CRC

Hdbk. Data Organic CPDS., Vol. I, II, 1985)
92

Solubility: Highly soluble in water; soluble in alcohol, ether (Merck Index,

10th Ed., 1983); chloral hydrate is extremely soluble in water

(825 g/100 g water (Seidell, A. (1941) Solubilities of Organic

Compounds); soluble in chloroform (Condensed Chem.

Dictionary, 10th Ed., 1981).

Volatility: Vapor Pressure: 35 mm Hg @ 20°C (Encyc. Occupat. Health &

Safety, 1983; IARC, 1995).

Vapor Density: 5.1 (air = 1) (Patty. Indus. Hyg. & Tox, 1981-

1982).

Stability: Unstable (Goodman (1985) Pharm. Basis Therap., 7th Ed.).

Reactivity: Forms chloral hydrate when dissolved in water and forms chloral

alcoholate when dissolved in alcohol (Merck Index, 10th Ed.,

1983).

Octanol/Water

Partition Coefficient: No data.

9.1.4 Technical Products and Impurities

Chloral is produced in a technical grade with a minimum of 94% purity (Hawley (1981)

Condensed Chem. Dictionary, 10th Ed.). Instead of water, various alcohols can be added to

chloral to form hemiacetals. Chloral alcoholate and chloral betaine are simple adducts and

laboratory anesthetic alpha-chloralose is a complex adduct. Chloral is an unstable oil that does

not lend itself well to pharmaceutical formulations; therefore, in medicine it was introduced in

the form of chloral hydrate (Goodman (1985) Pharm. Basis Therap, 7th Ed.) The typical

impurities (max.) are as follows: water, 0.06%; 2,2-dichloroethane, 0.3%; 2,2,3-trichlorobutanal,

0.01%; hydrogen chloride, 0.06%; and chloroform (IARC, 1995).

9.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC

(1995).

9.2.1 Production

The principal use of chloral in the U.S. was in the manufacture of DDT. According to

IARC (1995), when the use of DDT was banned in the U.S. in 1972, the demand for chloral in

the U.S. rapidly declined. DDT is still produced in the U.S. for use in tropical countries (IARC,

1995).

- U.S. Production: (1969) 2.83 x 1010 g; (1975) 2.27 x 1010 g (SRI).
93

- Import Volumes: (1984) 1.02 x 108

 g (Bureau of the Census. U.S. Imports for

Consumption and General Imports, 1984).

- Export Volumes: (1972 and 1975) negligible.

9.2.2 Uses

Chloral is used in the spraying and pouring of polyurethanes (NRC, 1977); as a chemical

intermediate for the herbicide trichloroacetic acid and chloral hydrate (HSDB, 1996); used to

induce swelling of starch granules at room temperature (Kirk-Othmer, 1978-present); and as an

intermediate in DDT and other insecticides, including: methoxychlor, dichlorvos, naled, and

trichlorofon (Sittig. (1985) Handbook Toxic hazard Chem & Carcinog, 2nd Ed.; IARC, 1995). 

Estimated use in the U.S. in 1975 was in the manufacture of DDT (40%); methoxychlor,

dichlorvos, and naled (10%); and miscellaneous other applications (50%) (IARC, 1995).

9.2.3 Disposal

Chloral is a potential candidate for liquid injection incineration at a temperature range of

650 to 1,600°C and a residence time of 0.1 to 2 seconds; for rotary kiln incineration at a

temperature range of 820 to 1,600°C and residence times of seconds for liquids and gases, and

hours for solids; and for fluidized bed incineration at a temperature range from 450 to 980°C and

residence times of seconds for liquids and gases, and longer for solids. (USEPA (1981) 

Engineering Handbook for Hazardous Waste Incineration).

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal

practices are subject to significant revision. Prior to implementing land disposal of waste residue

(including waste sludge), consult with environmental regulatory agencies for guidance on

acceptable disposal practices (HSDB Technical Review Panel; HSDB, 1996).

9.3 POTENTIAL FOR HUMAN EXPOSURE

9.3.1 Natural Occurrence

Chloral is not known to occur as a natural product (IARC, 1995).

9.3.2 Occupational

Exposure to chloral is thought to be primarily via inhalation and dermal contact with the

vapor (HSDB, 1996). Chloral has been detected in the work environment during spraying and

casting of polyurethane foam, identified as an auto-oxidation product of trichloroethylene during

extraction of vegetable oil, and also identified at the output of etching chambers in

semiconductor processing (IARC, 1995).
94

9.3.3 Environmental

9.3.3.1 Environmental Releases

Chloral may be released to the environment from the synthesis of methoxychlor and

DVPP, and also from wood processing plants in the chlorination portion of the bleaching process

(HSDB, 1996). It is a reactive intermediate metabolite of trichloroethylene (IARC, 1995).

9.3.3.2 Monitored Environmental Media Levels

Air: No data.

Water: Chloral is formed during aqueous chlorination of humic substances and amino

acids (IARC, 1995). It may therefore occur in drinking water as a result of chlorine disinfection

of raw waters containing natural organic substances. The concentration of chloral measured in

drinking water in the U.S. is summarized in Table 9-1.

Chloral was reported in the drinking water supplies of several U.S. cities as follows: 

Philadelphia, PA - 5 μg/l; Seattle, WA - 3.5 μg/l; Cincinnati, OH - 2 μg/l; Terrebonne Parish, LA

- 1 μg/l; New York City, NY - 0.02 μg/l; Grand Forks, ND - 0.01 μg/l (HSDB, 1996). In surface

water samples taken from water of New Orleans/Baton Rouge, chloral was reported at a mean

concentration of 1.0 μg/l (HSDB, 1996).

Chloral has also been detected in the spent chlorination liquor from bleaching of sulfite

pulp after oxygen treatment at concentrations of <0.1 to 0.5 g/ton of pulp. Trace amounts have

also been reported from photocatalytic degradation of trichloroethylene in water (IARC, 1995).

Other Media: Chloral is a reactive intermediate metabolite of trichloroethylene (IARC,

1995).

Table 9-1. Concentrations of Chloral (As Chloral Hydrate)

in Drinking Water in the United States

Water Type (Location) Concentration (μg/L)

Tap water (reservoir)

Surface, reservoirs, lake, and groundwater

Tap water

Distribution system

Surface water

7.2-18.2

1.7-3.0

0.01-5.0

0.14-6.7

6.3-28

Source: IARC, 1995.
95

9.3.3.3 Environmental Fate and Transport

9.3.3.3.1 Summary

Fate in Terrestrial Environments: The dominant fate of chloral released to soils is

rapid hydrolysis by soil water to form chloral hydrate. Volatilization is likely to be important

only in the event of a spill onto relatively dry soil.

Fate in the Atmosphere: Chloral should react rapidly with the moisture in air to form

chloral hydrate. Although photo-oxidation by hydroxyl radicals will likely occur to some extent,

the reaction rate is much slower than for hydrolysis; the half-life for the vapor phase reaction of

chloral with photochemically produced hydroxy radicals is estimated to be 10.8 hours.

Fate in Aquatic Environments: The dominant fate of any chloral released to water is

rapid hydrolysis to form chloral hydrate. Although this hydrolysis reaction is reversible, the

equilibrium constant favors the formation of chloral hydrate (27,000 to 1). Chloral is thus

essentially removed from the water. Volatilization, sorption to suspended solids, and

bioconcentration are not expected to be significant.

9.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: No data are available concerning the sorption of chloral to

soil. However, since chloral reacts rapidly with water to form chloral hydrate, it should also react

rapidly with soil moisture. Since chloral hydrate is extremely soluble in water (8,250 g/L) and is

not expected to sorb to soil, chloral hydrate has the potential to leach through soils (HSDB,

1996).

 

Volatilization: Chloral has a relatively high vapor pressure (35 torr at 25 degrees C) and

should therefore volatilize rapidly from dry surfaces. Chloral reacts rapidly with water to form

chloral hydrate thus precluding any significant volatilization of chloral from water (HSDB,

1996).

Bioconcentration: No data are available concerning the bioconcentration of chloral. 

However, since chloral reacts rapidly with water to form chloral hydrate, bioconcentration would

not be expected to be a significant fate process. Since chloral hydrate is extremely soluble in

water (8,250 g/L), bioconcentration in aquatic organisms should not be significant for chloral

hydrate (HSDB, 1996).

9.3.3.3.3 Transformation and Degradation Processes

Biodegradation: No data are available concerning the biodegradability of chloral. 

However, since chloral reacts rapidly with water to form chloral hydrate, biodegradation would

not be expected to be a significant fate process.

Photodegradation: The half-life for the vapor phase reaction of chloral with

photochemically produced hydroxy radicals is estimated to be 10.8 hours. No data are available
96

on the photolytic sensitivity of chloral. However, acetaldehyde has a UV absorption maximum at

293 nm which suggests that chloral will also absorb some UV light (HSDB, 1996).

Hydrolysis: Chloral reacts exothermically with water to form chloral hydrate. Because

the equilibrium constant for this reaction is 3.6 x 10-5, very little chloral will remain in solution

(HSDB, 1996)

9.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

9.4.1 General U.S. Population

The general population can be exposed to chloral during its production and use, from

drinking chlorinated water, and from pharmaceutical use (IARC, 1995).

9.4.2 Occupational Exposure

Results of the National Occupational Exposure Survey conducted between 1981 and 1983

indicate that 2,757 employees in the U.S. were potentially exposed to chloral (IARC, 1995). The

estimate was based on a survey of companies and did not involve measurements of actual

exposure.

9.4.3 Consumer Exposure

No data concerning consumer exposure were found.

9.5 CHAPTER SUMMARY

Table 9-2 summarizes the findings of chloral.
97

Table 9-2. Chloral Summary

Estimates Support

Uses Chemical intermediate for manufacture of

pesticides; used in spraying and pouring of

polyurethanes

Well documented

Production 2.3 x 107

 kg 1975 data

Releases No available data

Properties/Fate Soluble in water; rapid hydrolysis to chloral

hydrate; no significant bio-concentration

expected

Media Levels Air: no data

Drinking water supplies: six U.S. cities -

0.02 ug/l to 5 mg/l

General Population

Exposure

No available data

Special Population

Exposures

2,757 employees potentially exposed Data from early 1980s
98

10.0 CHLORAL HYDRATE

10.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

10.1.1 Nomenclature

CAS No. 302-17-0

Synonyms: 1,1,1-trichloro-2,2-dihydroxyethane; 2,2,2-trichloro-1,1-ethanediol;

trichloroacetaldehyde hydrate; trichloroacetaldehyde monohydrate;

trichloroethylidene glycol; 2,2,2-trichloroethane-1,1-diol

Trade Names: Kessodrate, Noctec, Phaldrone, Sontec, Chloralvan, Chloralex

10.1.2 Formula and Molecular Weight

Molecular Formula: C2H3Cl302

Molecular Weight: 165.42

10.1.3 Chemical and Physical Properties

Description: Transparent, colorless crystals (Sax, 1984); aromatic,

penetrating and slightly acrid odor; slightly bitter, caustic taste

(Merck Index, 11th Ed., 1989).

Boiling Point: 96.3°C @ 764 mm Hg (decomp) (CRC Handbook Chem. &

 Physics, 1991-1992).

Melting Point: -57°C (Merck Index, 11th Ed., 1989).

Density: 1.908 @ 20°C/4°C (CRC Handbook Chem. & Physics, 1991-

1992).

Spectroscopy Data: IR: 5423 (Coblentz Society Spectral Collection); NMR: 10362

(Sadtler Research Laboratories Spectral Collection); Mass:

1054 (Atlas of Mass Spectral Data) (Weast, 1985); intense

mass spectral peaks: 82 m/z, 111 m/z, 146 m/z (Pfleger, 1985).

Solubility: 2.4 g/ml water @ 0°C; 14.3 g/ml water @ 40°C; 8.3 g/ml water

at 25°C. Sparingly soluble in turpentine, petroleum ether,

benzene, toluene, carbon tetrachloride; 1 g/68 g carbon

disulfide; 1 g/1.3 ml alcohol; 1 g/1.4 ml olive oil; freely soluble
99

in acetone, methyl ethyl ketone; 1 g/2 ml chloroform; 1 g/1.5

ml ether; 1 g/0.5 ml glycerol (Merck Index, 11th Ed., 1989).

Volatility: No data.

Stability: Slowly volatilizes on exposure to air (Merck Index, 11th Ed.,

1989). Aqueous solutions of chloral hydrate decomposed

rapidly when exposed to ultraviolet light, with the formation of

hydrochloric acid, trichloroacetic acid, and formic acid. A 1%

solution lost about 5% of its strength after storage at room

temperature for 20 weeks; aqueous solutions are likely to

develop mold growth (Martindale. Extra Pharmacopeia, 28th

Ed., 1982).

Reactivity: No data.

Octanol/Water

Partition Coefficient: log Kow = 0.99 (Hansch. Log P Database, 1987)

10.1.4 Technical Products and Impurities

Dosage forms for chloral hydrate are the following: capsules: 250 and 500 mg, and 1 g;

elixir: 500 mg/5 ml; suppositories: 325, 500, and 650 mg; syrup: 250 and 500 mg/5 ml

(Remington’s Pharm. Sci., 17Ed., 1985). Noctec capsules contain 250 or 500 mg chloral hydrate

per capsule; Noctec syrup contains 500 mg chloral hydrate per 5 cc (AHFS drug Information 92

Plus Suppl’s). Chloral hydrate is produced in technical and USP grades (Sax, 1987). For

chloropent injection; intravenous anesthetic; each ml contains chloral hydrate 42.5 mg;

magnesium sulfate 21.2 mg; pentobarbital 8.86 mg; ethyl alcohol 14.25%; propylene glycol

33.8%; and purified water, qs (for cattle and horses) (Vet Pharm. & Biolog., 1982-1983). 

Chloral hydrate capsules contain not less than 95.0% and not more than 110.0% of the labeled

amount of chloral hydrate; chloral hydrate syrup contains not less than 95.0% and not more than

110.09% of the labeled amount of chloral hydrate (USPC. USP XXII & NF XVII 1990, Plus

Suppl’s).

10.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

10.2.1 Production

U.S. Production: (1972) 1.14 x 1010 g (anhydrous chloral); (1975) 5.9 x 108

 g

 (SRI).
100

Import Volume: (1972) 2.83 x 107

 g; (1975) 4.8 x 107 g (SRI); (1984) 5.41 x 106

g; 4.67 x 1012 g (Bureau of the Census. U.S. Imports for

Consumption and General Imports, 1984; 1986).

Export Volume: No data.

10.2.2 Uses

Chloral hydrate is used in medication as a hypnotic and sedative (Merck Index, 11th

Ed., 1989; IARC, 1995). It is also used as a rubefacient in topical preparations (AHFS Drug

Information 92 Plus Suppl’s); veterinary medication (Vet Pharm. & Biolog., 1982-1983); and as

a glue peptizing agent (Kirk-Othmer, 1980).

10.2.3 Disposal

Chloral hydrate is a waste chemical stream constituent which may be subjected to

ultimate disposal by controlled incineration, preferably after mixing with another combustible

fuel. Care must be exercised to assure complete combustion to prevent the formation of

phosgene; an acid scrubber is necessary to remove the halo acids produced (USEPA. 1981.

Engineering Handbook of Hazardous Waste Leachate). Solvent extraction is a wastewater

treatment technology that has been investigated for chloral hydrate (USEPA. 1982. Engineering

Handbook of Hazardous Waste Leachate).

10.3 POTENTIAL FOR HUMAN EXPOSURE

10.3.1 Natural Occurrence

Chloral hydrate is not known to occur as a natural product (IARC, 1995).

10.3.2 Occupational

Specific information concerning potential for occupational exposure were not found.

10.3.3 Environmental

10.3.3.1 Environmental Releases

Specific data on environmental releases of chloral hydrate were not found.

10.3.3.2 Monitored Environmental Media Levels

Air: No data.

Water: Chloral hydrate may occur in drinking water as a result of chlorine disinfection

of raw waters containing natural organic substances. The concentration of chloral measured in

drinking water (as chloral hydrate) in the U.S. is summarized in Section 9, Table 9-1.
101

Other Media: Chloral hydrate has been detected in human milk (HSDB, 1996). Data

were not available in HSDB (1996) on the mechanism whereby the breast milk became

contaminated.

10.3.3.3 Environmental Fate and Transport

10.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: Since chloral hydrate is very soluble in water

(8,250 g/L), it is not expected to sorb to soil and thus has the potential to leach through soils. No

information is available on the biodegradation of chloral hydrate.

Fate in the Atmosphere: Any chloral hydrate released to the atmosphere is expected to

be readily scavenged during precipitation events. Chloral hydrate may also undergo photolysis,

but the available data are not adequate to determine its relative importance.

Fate in Aquatic Environments: Because of its very high water solubility, chloral

hydrate is not expected to volatilize, sorb to suspended solids or sediments, or bioconcentrate. 

No information is available on the biodegradation of chloral hydrate.

10.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: No data are available concerning the sorption of chloral

hydrate to soil. However, since chloral hydrate is very soluble in water (8,250 g/L), it is not

expected to sorb to soil and thus has the potential to leach through soils (HSDB, 1996).

Volatilization: Although vapor pressure data for chloral hydrate are not readily

available, chloral hydrate has been reported to slowly volatilize from surfaces when exposed to

air. Because of its very high water solubility, volatilization from water is not expected to be

significant (HSDB, 1996).

Bioconcentration: No data are available concerning the bioconcentration of chloral

hydrate. However, since chloral hydrate is very soluble in water (8,250 g/L), bioconcentration in

aquatic organisms should not be significant (HSDB, 1996).

10.3.3.3.3 Transformation and Degradation Processes

Biodegradation: No information is available on the biodegradation of chloral hydrate

(HSDB, 1996).

Photodegradation: Although no studies have apparently been published that

quantitatively have examined direct atmospheric photolysis of chloral hydrate, a 1 percent
102

aqueous solution of chloral hydrate was reported to have lost 5 percent of its strength after

storage for 20 weeks at room temperature. Hydrochloric acid, trichloroacetic acid, and formic

acid were formed as products (HSDB, 1996).

Hydrolysis: Hydrolysis is not expected to be a significant fate process for chloral

hydrate.

10.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

Human exposure to chloral hydrate can occur during its production and use, from

pharmaceutical use, and from drinking chlorinated water (IARC, 1995). Specific exposure data

and data on estimates of exposed populations were not found. The general population may be

potentially exposed from ingestion of drinking water contaminated with chloral hydrate. The

occupational population may be exposed in the workplace during production and use. The

consumer population may be potentially exposed from use of pharmaceuticals.

10.5 CHAPTER SUMMARY

Table 10-1 summarizes the findings of chloral hydrate.

Table 10-1. Chloral Hydrate Summary

Estimates Support

Uses Pharmaceutical Well documented

Production 5.9 x 105

 kg 1975 data

Releases No available data

Properties/Fate Water soluble; no significant

bioconcentration expected; no information

on biodegradation

Media Levels No available data

General Population

Exposure

No available data

Special Population

Exposures

No available data
103

11.0 MONOCHLOROACETIC ACID

11.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

11.1.1 Nomenclature

CAS No.: 79-11-8

Synonyms: Acetic acid; chloro-; alpha-chloroacetic acid; chloracetic acid;

chloroethanoic acid; monochloroacetic acid; monochloroethanoic acid

Trade Names: NCI-C60231

11.1.2 Formula and Molecular Weight

Molecular Formula: C2H3Cl02

Molecular Weight: 94.50

11.1.3 Chemical and Physical Properties

Description: Colorless or white crystals (Merck Index, 11th Ed., 1989). 

Characteristic penetrating odor similar to vinegar.

Boiling Point: All three forms (alpha, beta, gamma) boil at 189° C (Merck

Index, 11th Ed., 1989).

Melting Point: Exists in three physical modifications: alpha 63° C; beta 55-

56° C; gamma 50° C (Merck Index, 11th Ed., 1989).

Density: 1.4043 @ 40° C/4° C (Gardner’s Chem Synonyms, Trade

Names, 1987).

Spectroscopy Data: Index of Refraction: 1.4351 @ 55° C/D; Sadtler Ref. Number: 

2094 (IR, Prism (Weast, 1988-89); IR: 5567 (Coblentz Society

Spectral Collection) (Weast, 1985); NMR: 128 (Sadtler

Research Laboratories Spectral Collection) (Weast, 1985);

Mass; 196 (Weast, 1985).

Solubility: Very soluble in water, slightly soluble in chloroform (Weast,

1988-89); Soluble in acetone, carbon disulfide (Weast, 1979);

soluble in benzene (Merck Index, 1989); soluble in ethanol,

diethyl ether (Worthing, Pesticide Manual, 1979); soluble in

carbon tetrachloride (Encyc. Occupat. Health & Safety, 1983).
104

Volatility: Vapor Pressure: 1 mm Hg @ 43.0° C (Patty, Indus. Hyg. &

Tox., 3rd Ed., 1981-82).

Vapor Density: 3.26 (air = 1) (Sax, 1984).

Stability: No data.

Reactivity: Highly reactive; chemically reacts with ammonia to form

glycine and with aniline to form a precursor for indigo dyes

(Encyc. Occupat. Health & Safety, 1983).

Octanol/Water

Partition Coefficient: log Kow = 0.22 (Hansch, 1981)

11.1.4 Technical Products and Impurities

Monochloroacetic acid is produced in technical and medicinal grades with 99.5%

purity. Data were not available for impurities.

11.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

11.2.1 Production

U.S. Production: (1978) 3.50 x 1010 g (SRI); (1982) probably greater than 6.81 x 106

 g

(SRI); Chemical Int. For sodium carboxymethyl cellulose, 60%; for

herbicides, 30%; for other derivatives (e.g., glycine, thioglycolic acid,

pharmaceuticals, and indigoid dyes), 10% (SRI, 1979).

Import Volumes: (1978) 1.25 x 1010 g (SRI); (1982) 1.35 x 1010 g (SRI).

11.2.2 Uses

Monochloroacetic acid is used as a chemical intermediate for pharmaceuticals (e.g.,

vitamin A); chemical intermediate for indigoid dyes; and as a herbicide (Merck Index, 1989). It

is also used as a preservative, bacteriostat, intermediate in production of synthetic caffeine;

carboxymethyl cellulose; ethyl chloracetate; glycine; scariosine; thioglycolic acid; EDTA; 2,4-D;

2,4,5-T (Hawley’s Condensed Chem. Dict., 11th Ed., 1987). It has also been recommended as a

defoliant (Pesticide Manual, 4th Ed., 1974, p.106).

11.2.3 Disposal

No data were identified.
105

11.3 POTENTIAL FOR HUMAN EXPOSURE

11.3.1 Natural Occurrence

No information on the natural occurrence of chloracetic acid was found.

11.3.2 Occupational

No specific information on potential for occupational exposure of chloracetic acid was

found.

11.3.3 Environmental

11.3.3.1 Environmental Releases

Chloracetic acid may enter the environment in emissions and wastewater from its

production and use as a chemical intermediate primarily in the manufacture of chlorophenoxy

herbicides and carboxymethyl cellulose. Such releases of the chemical would be limited to

industrial settings (HSDB, 1996). Chloroacetic acid has been used as a pre-emergent herbicide

and defoliant, and if it is still used for these applications, its use would constitute an emission

source and ground contamination of a more general nature (HSDB, 1996).

Total Toxic Release (TRI) releases for years 1987 to 1994 are shown in Table 11-1. 

The receiving media are air, water, land, and for underground injection, POTW transfer, and

other transfer. These releases are reported from manufacturing and processing facilities. Only

certain facilities are required to report, and therefore may not capture all releases.

Table 11-1. Release of Chloroacetic Acid (lbs/yr)

Year

Number of

Reporting

Facilities

Fugitive Air

Releases Stack Air

Releases

Surface

Water

Release

Underground

Injection

Land

Disposal

POTW

Transfer

Other

Transfers Total

1987 34 24229 4383 29956 280 0 1380 4010 64272 

1988 37 21660 5159 850 10 0 10727 9406 47849 

1989 35 20616 4229 1524 10 0 9717 4096 40227 

1990 37 20660 4759 1691 0 0 1785 6779 35711 

1991 36 60745 446920 1696 0 123675 3279 6444 642795 

1992 31 10778 1024 3199 0 0 1792 3147 19971 

1993 29 5796 767 8719 0 750 1433 2219 19713 

1994 32 5983 710 10178 0 950 1015 6259 25127 

Source: TRI, 1996.
106

11.3.3.2 Monitored Environmental Media Levels

Air: Data were not found for monitored levels in air.

Water: Between the spring of 1988 and the winter of 1989, grab samples were

collected at the clearwell effluents (after disinfection) from 35 treatment facilities and analyzed

by gas chromatography/mass spectroscopy (GC/MS). The concentration of monochloroacetic

acid was <1.0 to 1.2 μg/L (U.S. EPA, 1994). Chloroacetic acid was also found in a study where

concentrated humic acid from a coastal North Carolina lake was chlorinated (U.S. EPA, 1994).

Other Media: Data were not found for monitored levels in other media.

11.3.3.3 Environmental Fate and Transport

11.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of chloroacetic acid released to

or into soils is biodegradation. Although no soil biodegradation studies with chloroacetic acid

have been reported, studies with wastewater and river water inocula indicate that biodegradation

in soil will be a relatively rapid process. This ready biodegradability should minimize the

possibility of any significant leaching of chloroacetic acid into groundwater.

Fate in the Atmosphere: Because of its high water solubility and slow rates of photooxidation and photolysis, any chloroacetic acid released into the atmosphere will likely be

scavenged during precipitation events before any significant photodegradation occurs.

Fate in Aquatic Environments: The dominant fate of chloroacetic acid released to

surface waters is biodegradation (predicted half-life of days). Bioconcentration and sorption to

sediments and suspended solids are not expected to be significant transport/partitioning

processes.

11.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficient (log

Koc) for chloroacetic acid (0.08) indicates that adsorption to soil, sediment, and suspended solids

is not a significant fate process. As a consequence, chloroacetic acid has the potential for high

mobility in soil; however, the extent of migration will be minimized because of the ready

biodegradability of chloroacetic acid (HSDB, 1996; U.S. EPA, 1996).

 

Volatilization: The very low predicted Henry's Law constant for chloroacetic acid

(<10-7 atm-m3

/mol) indicates that minimal volatilization is expected from water bodies. Because

of its relatively low vapor pressure (<1 torr), minimal volatilization from soil surfaces is

expected (HSDB, 1996; U.S. EPA, 1996).
107

Bioconcentration: A bioconcentration factor of 0.86 is predicted for chloroacetic acid

based on its very low measured log octanol/water partition coefficient of 0.22. Therefore,

bioconcentration in aquatic organisms should not be significant and there is little potential for

biomagnification in the food chain (HSDB, 1996; U.S. EPA, 1996).

11.3.3.3.3 Transformation and Degradation Processes

Biodegradation: Chloroacetic acid is expected to undergo ultimate biodegradation in

aerobic environmental settings with a half-life on the order of days. Degradation under anaerobic

conditions is expected to proceed more slowly with a predicted half-life on the order of weeks. 

In laboratory tests using sewage or acclimated sludge inocula, chloroacetic acid readily

undergoes biodegradation with greater than 70-90 percent degradation being reported in 5-10

days. The results of river water studies indicate 73 percent mineralization (i.e., conversion to

carbon dioxide) in 8-10 days (HSDB, 1996; U.S. EPA, 1996; Howard et al., 1991).

Photodegradation: Photolysis in the atmosphere or in aquatic environments is

expected to proceed very slowly with predicted half-lives on the order of months to years. 

Chloroacetic acid does not appreciably absorb UV light above 290 nm and thus will not directly

photolyze. The presence of sensitizers such as p-cresol and tryptophan that generate superoxide

radicals has been shown to increase the rate of photodechlorination by up to 16-fold. Based on

the estimated reaction rate constant of chloroacetic acid with hydroxyl radicals, the estimated

half-life of chloroacetic acid in the atmosphere is on the order of weeks to months (HSDB, 1996;

Howard et al., 1991).

Hydrolysis: Based upon the results of darkened controls during photolysis experiments,

the half-life of chloroacetic acid is on the order of years (HSDB, 1996; Howard et al., 1991)

11.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

Data were not found for human exposure and population estimates.

11.5 CHAPTER SUMMARY

Table 11-1 summarizes the findings of monochloroacetic acid.
108

Table 11-2. Monochloroacetic Acid Summary

Estimates Support

Uses Chemical intermediate; herbicide Well documented

Production 6.81 x 103 kg/yr 1982 data

Releases 25,127 lbs - all media 1994 TRI data

Properties/Fate Very soluble in water; no significant

bioconcentration or biodegradation expected

Media Levels Air: no available data

Water samples from treatment facilities -

<1.0 to 1.2 ug/l

35 facilities

General Population

Exposure

No available data

Special Population

Exposures

No available data
109

12.0 DICHLOROACETIC ACID

12.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from IARC Monographs, Volume 63, 1995.

12.1.1 Nomenclature

CAS No.: 79-43-6

Synonyms: Bichloracetic acid; DCA; CDA (acid); DCAA; dichloracetic acid;

dichlorethanoic acid; dichloroethanoic acid; 2,2-dichloroethanoic acid

12.1.2 Formula and Molecular Weight

Molecular Formula: C2H2Cl202

Molecular Weight: 128.94

12.1.3 Chemical and Physical Properties

Description: Colorless to slightly yellowish liquid with a pungent acid-like

odor (Merck Index, 1989; Hoechst Chemicals, 1990).

Boiling Point: 194°C

Melting Point: 13.5°C

Density: 1.5634 @ 20°C/4°C

Spectroscopy Data: Infrared (prism [2806]; grating [36771]), nuclear magnetic

resonance (proton [116], C-13 [500], and mass spectral data

have been reported (Sadtler Research Laboratories, 1980;

IARC, 1995).

Solubility: Soluble in water, acetone, ethanol, and diethyl ether; also

soluble in ketones, hydrocarbons, and chlorinated hydrocarbons

(IARC, 1995). In aqueous solution, dichloroacetic acid and

dichloroacetate exist as an equilibrium mixture, the proportions

of each depending primarily on the pH of the solution. The pKa

of dichloroacetic acid is 1.48 @ 25°C.

Volatility: Vapor Pressure - 0.19 mbar (19 Pa) @ 20°C (Hoechst

Chemicals, 1990).

Vapor Density - No data.
110

Reactivity: Highly corrosive and attacks metals; releases hydrogen chloride

gas (see IARC, 1992) when heated (Hoechst Chemicals, 1990).

Octanol/Water

Partition Coefficient: log P, 0.92 (Hansch, 1995)

12.1.4 Technical Products and Impurities

Dichloroacetic acid is available commercially at a purity of 99% with a maximum of

0.3% water (Hoechst Chemicals, 1990; Spectrum Chemical Mfg Corp., 1994)

12.2 PRODUCTION AND USE

12.2.1 Production

Figures for the production and use of dichloroacetic acid in the U.S. or throughout the

world are not available (IARC, 1995).

12.2.2 Uses

Dichloroacetic acid is presently of little economic importance. Its acid chloride and

methyl ester, however, are used as intermediates in the manufacture of agrochemicals and the

pharmaceutical, chloramphenicol (IARC, 1995). Dichloroacetic acid is also a starting material

for the production of glyoxylic acid, dialkyloxy and diaryloxy acids, and sulfonamides. The

compound is used as a test reagent for analytical measurements during the manufacture of

polyethylene terephthalate and as a medical disinfectant, in particular as a substitute for

formaldehyde (IARC, 1995). It has been considered for use in the treatment of lactic acidosis,

diabetes mellitus, hyperlipoproteinaemia, and several other disorders; however, it has never been

marketed for any of these purposes (Merck Index, 1989).

12.2.3 Disposal

No information concerning disposal methods for dichloroacetic acid was identified.

12.3 POTENTIAL FOR HUMAN EXPOSURE

12.3.1 Natural Occurrence

Dichloroacetic acid is not known to occur as a natural product.

12.3.2 Occupational

No specific information concerning the potential for human exposure in an occupational

setting was found.
111

12.3.3 Environmental

12.3.3.1 Environmental Releases

No information concerning environmental releases of dichloroacetic acid was found.

12.3.3.2 Monitored Environmental Media Levels

Air: No data available.

Water: Dichloroacetic acid is produced as a by-product during aqueous chlorination of

humic substances and therefore it may occur in drinking water after chlorine disinfection of raw

waters containing natural substances (IARC, 1995). The concentrations of dichloroacetic acid

measured in various water sources and reported in various studies are summarized in Table 12-1. 

According to IARC (1995), it has been identified as a major chlorinated by-product of the

photocatalytic degradation of tetrachloroethylene in water and a minor by-product of the

degradation of trichoroethylene.

Other Media: In humans, dichloroacetic acid is a reactive intermediate metabolite of

trichloroethylene and an end-metabolite of 1,1,1,2-tetrachloroethane. Dichloroacetic acid has

also been reported as a biotransformation product of methoxyflurane (IARC, 1995) and

dichlorvos (IARC, 1995). It may occur in the tissues and fluids of animals treated with

dichlorvos for helminthic infections (IARC, 1995).

Table 12-1. Concentrations of Dichloroacetic Acid in Water

Water Type (Location) Concentration Range (μg/L)

Drinking Water (chlorinated tap water (USA) 63.1 - 133

Drinking Water (chlorinated surface, reservoir, lake, and groundwater) (USA) 5.0 - 7.3

Chlorinated Surface Water (USA) 9.4 - 23

Chlorinated Drinking Water (USA) 8 - 79

Swimming Pool (Germany) indoors: 0.2 - 10.6

open air: 83.5 - 181.0a

Surface Water (downstream from a paper mill) &Austria) <3 - 522

Biologically Treated Kraft Pulp Mill Effluent (Malaysia) 14 - 18

a The higher levels found in open-air swimming pools may be due to the input of organic material by swimmers.

Source: IARC, 1995.
112

12.3.3.3 Environmental Fate and Transport

No information is readily available on the environmental fate and transport of

dichloroacetic acid. However, its environmental fate is expected to be similar to that of

monochloroacetic acid and trichloroacetic acid. The environmental fate and transport of

monochloroacetic acid and trichloroacetic acid are discussed in Sections 11.3.3.3 and 13.3.3.3,

respectively.

12.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

12.4.1 General U.S. Population

The general population is potentially exposed to dichloroacetic acid through the

ingestion of chlorinated drinking water, contact with surface water contaminated with this

chemical, and chlorinated water in swimming pools.

12.4.2 Occupational Exposure

The National Occupational Exposure Survey conducted between 1981 and 1983

indicated that 1,592 employees in the United States were potentially exposed to dichloroacetic

acid in 39 facilities (IARC, 1995).

12.4.3 Consumer Exposure

Data were not found on consumer exposure to dichloroacetic acid.

12.5 CHAPTER SUMMARY

Table 12-2 summarizes the findings of dichloroacetic acid.

Table 12-2. Dichloroacetic Acid Summary

Estimates Support

Uses Chemical intermediate

Production No available data

Releases No available data

Properties/Fate Water soluble

Media Levels Water: 5-133 ug/l

General Population

Exposure

No available data

Special Population

Exposures

1,592 employees potentially exposed Data from early 1980s
113

13.0 TRICHLOROACETIC ACID

13.1 CHEMICAL AND PHYSICAL PROPERTIES

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

13.1.1 Nomenclature

CAS No.: 70-03-9

Synonyms: Acetic acid; trichloro-, <TCA’, trichloroethanoic acid

Trade Names: AMCHEM Grass Killer, Nata, Natal

13.1.2 Formula and Molecular Weight

Structural Formula: C2HCl302

Molecular Weight: 163.40

13.1.3 Chemical and Physical Properties

Description: Colorless to white, crystalline solid; sharp, pungent odor

(NIOSH Pocket Guide Chem. Haz., 1994).

Boiling Point: 195.5°C (CRC Handbook Chem. & Physics, 76th Ed., 1995-

96).

Melting Point: -57.5°C (CRC Handbook Chem. & Physics, 76th Ed., 1995-

96).

Density: 1.6126 @ 64°C (CRC Handbook Chem. & Physics, 76th Ed.,

1995-96).

Spectroscopy Data: Index of refraction: 1.4603 @ 61°C (CRC Handbook Chem. &

Physics, 76th Ed., 1995-96); IR: 2376 (Coblentz Society

Spectral Collection); UV: 1-6 (Organic Electronic Spectral

Data); NMR: 6 (Sadtler Research Laboratories Spectral

Collection); Mass: 1026 (Atlas of Mass Spectral Data) (Weast,

CRC Handbook Data Organic CPDS, Vol. I, II, 1985).

Solubility: In water - 1306 g/100 g @ 25°C; in methanol - 2143 g/100 g @

25°C; in ethyl ether - 617 g/100 g @ 25°C; in acetone - 850

g/100 g @ 25°C; in benzene - 201 g/100 g @ 25°Cl in o-xylene

- 110 g/100 g @ 25°C (Kirk-Othmer. Encyc. Chem. Tech., 4th

Ed., Vol. 1, 1991-present); soluble in ethanol, ethyl ether;
114

slightly soluble in carbon tetrachloride (CRC Handbook Chem.

& Physics, 76th Ed., 1995-96).

Volatility: Vapor Pressure - 1 mm Hg @ 51.0°C (solid) (CRC Handbook

Chem. & Physics, 72nd Ed., 1991-1992).

Stability: Stable in the absence of moisture (Pesticide Manual, 8th Ed.,

1987); 2-year shelf life minimum, may cake however

(Herbicide Hdbk, 5th Ed., 1983).

Reactivity: Reacts with moisture, iron, zinc, aluminum, strong oxidizers

(Note: decomposes on heating to form phosgene and hydrogen

chloride. Corrosive to metals.) (NIOSH Pocket Guide Chem.

Haz., 1994).

Octanol/Water

Partition Coefficient: No data.

13.1.4 Technical Products and Impurities

Trichloroacetic acid is produced in a technical grade (chemically pure: a grade

designation signifying a minimum of impurities, but not 100% purity) and a USP grade

(Hawley’s Condensed Chem. Dict., 12th Ed., 1993).

13.2 PRODUCTION AND USE

The information/data presented in this section and the supporting references were

obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).

13.2.1 Production

- U.S. Production: (1975) greater than 3.60 x 106

 g; (1976) greater than 2.27 x

106 g (SRI).

- Import Volumes: (1984) 3.67 x 109 g/chloroacetic acid (Bureau of the

Census. U.S. Imports for Consumption and General

imports, 1984).

- Export Volumes: (1984) 8.60 x 109 g (Halogenated Hydrocarbons, Bureau of

the Census. U.S. Exports, 1984).

13.2.2 Uses

Trichloroacetic acid is used as a chemical intermediate for the production of ethylene

glycol bis(trichloroacetate) and herbicides, sodium trichloroacetate and monuron-TCA; and used

as a lab reagent for biological applications (SRI). TCA has been used as an astringent and

antiseptic, and polymerization catalyst (Kirk-Othmer. Encyc. Chem. Tech., 4th Ed., Vol. 1,
115

1991-present). About 21,000-23,000 t/a of the TCA sodium salt are used worldwide as a

selective herbicide (Ullmann’s Encyc. Indust. Chem., 5th Ed., 1985-present).

13.2.3 Disposal

Reverse osmosis is a wastewater treatment technology that has been investigated for

trichloroacetic acid (USEPA, 1982, Management of Hazardous Waste Leachate). After mixing,

transfer into a drum and fill with water for drainage after 24 hours (Tox. & Hazard. Indus. Chem.

Safety Manual, 1988).

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal

practices are subject to significant revision. Prior to implementing land disposal of waste residue

(including waste sludge), consult with environmental regulatory agencies for guidance on

acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996).

13.3 POTENTIAL FOR HUMAN EXPOSURE

13.3.1 Natural Occurrence

Trichloroacetic acid is not known to occur naturally (IARC, 1995).

13.3.2 Occupational

The probable routes of occupational exposure are dermal contact and inhalation. 

Trichloroacetic acid is the major end metabolite of trichloroethylene and tetrachloroethylene in

humans and has been used as a biological marker of exposure to these compounds (IARC, 1995). 

Additionally, it is a metabolite of 1,1,1-trichoroethane and 1,1,1,2-tetrachloroethane and chloral

hydrate is rapidly oxidized to trichloroacetic acid in humans (IARC, 1995).

13.3.3 Environmental

13.3.3.1 Environmental Releases

The production of trichloroacetic acid and its use in organic synthesis, medicine,

pharmaceuticals, and as a herbicide may result in its release to the environment through

wastestreams (HSDB, 1996).

13.3.3.2 Monitored Environmental Media Levels

Air: No data.

Water: The concentrations of trichloroacetic acid in water are presented in Table 13-1.

Other Media: Trichloroacetic acid has been detected in the following foods(IARC,

1995):
116

Table 13-1. Concentrations of Trichloroacetic Acid in Water

Water Type (Location) Concentration Range (μg/L)

Chlorinated Tap Water (USA) (drinking water) 33.6 - 161

Chlorinated Drinking Water (USA) 4.23 - 53.8

Raw Water (USA) 95 - 2,120

Chlorinated Surface, Reservoir, Lake, and Groundwaters

(USA)

4.0 - 6.0

Chlorinated Surface Water (USA) 7.4 - 22

Chlorinated Drinking Water (USA) 15 - 64

Raw Water (USA) 60 - 1,630

Source: IARC, 1995.

• Seed of wheat, barley, and oats after treatment with trichloroacetic acid as

postemergent herbicide;

• Fruits and vegetables after irrigation with trichloroacetic acid contaminated water

(trace levels); and

• Field bean pods and seeds (0.13 to 0.43 mg/kg)

Concentration of trichloracetic acid was in irrigation water after the application of the

sodium salt (herbicide) to control canary grass on the banks of dry canals in the State of

Washington. The levels measured ranged from 53 to 297 ppb (HSDB, 1996).

13.3.3.3 Environmental Fate and Transport

13.3.3.3.1 Summary

The summary is based on the data presented in the subsequent fate and transport

subsections.

Fate in Terrestrial Environments: The dominant fate of trichloroacetic acid released

onto or into soils is biodegradation. Studies with wastewater and soil indicate that aerobic

biodegradation in soil will occur within weeks to months depending on the soil type, moisture

and temperature. However, the low reported Koc for trichloroacetic acid indicates that

trichloroacetic acid should have high mobility in soil and, therefore, significant leaching to

groundwater could occur, particularly in sandy soils.

Fate in the Atmosphere: Because of its moderate vapor pressure (<1 mm Hg at 25

degrees C), trichloroacetic acid should exist predominantly in the vapor phase in the atmosphere. 

Vapor phase trichloroacetic acid is degraded in the atmosphere by reaction with photochemically

produced hydroxyl radicals; the half-life for this reaction is estimated to be about 31 days.
117

Fate in Aquatic Environments: The dominant fate of trichloroacetic acid released into

surface waters is biodegradation (predicted weeks to months). Bioconcentration, sorption to

sediments and suspended solids, and volatilization are not expected to be significant

transport/partitioning processes.

13.3.3.3.2 Transport and Partitioning

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficient (Koc

= 1) for trichloroacetic acid indicates that adsorption to soil, sediment, and suspended solids is

not a significant fate process. Several laboratory and field soil studies confirm that

trichloroacetic acid shows little sorption to soils. As a consequence, trichloroacetic acid has the

potential for high mobility in soil (HSDB, 1996).

Volatilization: The very low predicted Henry's Law constant for trichloroacetic acid

(<10-7 atm-m3/mol) indicates that minimal volatilization is expected from water bodies. Because

of its relatively low vapor pressure (<1 mm Hg), minimal volatilization from soil surfaces is

expected (HSDB, 1996).

Bioconcentration: Bioconcentration factors measured in carp range from 0.4 to 1.7. 

Therefore, bioconcentration in aquatic organisms should not be significant and there is little

potential for biomagnification in the food chain (HSDB, 1996).

13.3.3.3.3 Transformation and Degradation Processes

Biodegradation: Trichloroacetic acid has been demonstrated to be undergo

biodegradation under aerobic conditions in soil and in laboratory tests with activated sludge

inocula (half-lives on the order of weeks to months). However, a noticeable lag period was

observed (i.e., a period in which slow degradation was followed by rapid degradation).

Degradation appears to be favored by warm moist conditions conducive to high microbiological

activity (HSDB, 1996).

Photodegradation: Based on the estimated reaction rate constant of trichloroacetic acid

with hydroxyl radicals, the estimated half-life of trichloroacetic acid in the atmosphere is about

31 days. No information is available on the photolysis of trichloroacetic acid. However,

monochloroacetic acid does not appreciably absorb UV light above 290 nm and thus will not

directly photolyze; the presence of sensitizers such as p-cresol and tryptophan that generate

superoxide radicals has been shown to increase the rate of photodechlorination by up to 16-fold

(HSDB, 1996; Howard et al., 1991).

Hydrolysis: No information is available on the hydrolytic half-life of trichloroacetic

acid. However, the hydrolytic half-life of monochloroacetic acid is on the order of years based

on the results of darkened controls during photolysis experiments (HSDB, 1996; Howard et al.,

1991)
118

13.4 HUMAN EXPOSURE AND POPULATION ESTIMATES

13.4.1 General U.S. Population

Based on available data, the general population could be potentially exposed to

trichloroacetic acid through ingestion of drinking water and foods contaminated with this

chemical.

13.4.2 Occupational Exposure

Estimates from a NIOSH survey conducted between 1981 and 1983 show that 35,124

employees in the U.S. were potentially exposed occupationally to trichloroacetic acid (IARC,

1995). This potentially exposed population were employees in seven different industries and

1,562 plants (IARC, 1995).

Trichloroacetic acid (3-116 mg/g creatinine) was found in the urine of employees in the

metal degreasing industry. These employees were exposed to trichloroethylene (HSDB, 1996).

13.4.3 Consumer Exposure

Data were not found for consumer exposures.

13.5 CHAPTER SUMMARY

Table 13-2 summarizes the findings of trichloroacetic acid.

Table 13-2. Trichloroacetic Acid Summary

Estimates Support

Uses Chemical intermediate; herbicide Well documented data

Production More than 2,270 kg 1976 data

Releases No available data

Properties/Fate Water soluble; no significant

bioconcentration is expected

Media Levels Air: no data

Drinking water: 4.2 to 161 ug/l

Raw water: 60 to 1,630 ug/l

General Population

Exposure

Special Population 35,124 employees potentially Data from early 1980s
119

14.0 DICHLORO-VINYL CYSTEINE

No information is readily available for this chemical.
120

REFERENCES

Agency for Toxic Substances and Disease Registry (ATSDR). (1990) Toxicological profile for

cis-1,2-dichloroethene, trans-1,2-dichloroethene, 1,2-dichloroethene. Update draft. Atlanta, GA.

ATSDR. (1995) Toxicological profile for 1,1,1-trichloroethane. Update. Atlanta, GA: Agency

for Toxic Substances and Disease Registry.

ATSDR. (1996a) Toxicological profile for 1,2-dichloroethene. Update. Atlanta, GA: Agency

for Toxic Substances and Disease Registry.

ATSDR. (1996b) Biennial Report to Congress (1991 and 1992) Atlanta, GA: U.S. Department

of Health and Human Services, Centers for Disease Control and Prevention, ATSDR. Internet

site: www.dhhs.gov.

ATSDR. (1997a) Toxicological profile for trichloroethylene. Update. Atlanta, GA: Agency for

Toxic Substances and Disease Registry.

ATSDR. (1997b) Toxicological profile for tetrachloroethylene. Update. Atlanta, GA: Agency

for Toxic Substances and Disease Registry.

American Conference of Governmental Indusrial Hygienists (ACGIH). (1995) Threshold limit

values (TLVs) for chemical substances and physical agents and biological exposure indices

(BEIs) for 1995-1996. Cincinnati, OH: ACGIH.

Andelman, JB. (1985) Human exposure to volatile halogenated organic chemicals in indoor and

outdoor air. Environ Health Perspect 62:313-318.

Andelman, J; Couch, A; Thurston, WW. (1986a) Inhalation exposures in indoor air to

trichloroethylene from shower water. Chapter 16. In: Environmental epidemiology. Kopfler, FC;

Craun, GC, eds. Chelsea, MI: Lewis Publishers. 

Andelman, JB; Meyers, SM; Wilder, LC. (1986b) Volatilization of organic chemicals from

indoor uses of water. In: Chemicals in the environment. Lester, JN; Perry, R; Sterritt, RM, eds.

London: Selper Ltd.

Arena, JM; Drew RH. (eds.) (1986) Poisoning—toxicology, symptoms, treatments, 5th ed. 

Springfield, IL: Charles C. Thomas Publishers.

Ashley, DL; Bonin, MA; Cardinali, FL; et al. (1994) Blood concentrations of volatile organic

compounds in a nonoccupationally exposed US population and in groups with suspected

exposure. Clin Chem 40(7):1401-1404.

Booth, NH; McDonald, LE. (eds.) (1982) Veterinary pharmacology and therapeutics, 5th ed.

Ames, IA: Iowa State University Press. 
121

Brown, HS; Bishop, DR; Rowan, CA. (1984) The role of skin absorption as a route of exposure

for volatile organic compounds in drinking water. Am J Publ Health 74(5):479-484.

Browning, E. (1965) Toxicity and metabolism of industrial solvents. New York: American

Elsevier.

Burmaster, DE. (1982) The new pollution-groundwater contamination. Environment 24(2)6-36.

Class, T; Ballschmiter, K. (1986) Chemistry of organic traces in Air - VI. Distribution of

chlorinated C1-C4 hydrocarbons in air over the northern and southern Atlantic Ocean. 

Chemosphere 15:413-427.

Clayton, GD; Clayton, FE. (eds.) (1981-1982) Patty’s industrial hygiene and toxicology: volume

2A, 2B, 2C: toxicology, 3rd ed. New York: John Wiley and Sons.

Clewell, HJ; Gentry, PR; Gearhart, JM; et al. (1995) Considering pharmacokinetic and

mechanistic information in cancer risk assessments for environmental contaminants: examples

with vinyl chloride and trichloroethylene. Chemosphere 31(1):2561-2578.

Cohn, P; Klotz, J; Bove, F; et al. (1994) Drinking water contamination and the incidence of

lukemia and non-Hodgkin’s lymphoma. Environ Health Perspect 102:556-561.

DHS. (1986) Organic chemical contamination of large public water systems in California.

Sacramento, CA: California Department of Health Services.

Dilling, WL, Tefertiller, NB; Kallos, GJ. (1975) Evaporation rates and reactivities of methylene

chloride, chloroform, 1,1,1-trichloroethane, tetrachloroethylene, and other chlorinated

compounds in dilute aqueous solutions. Environ Sci Technol 9:833-838.

Gearhart, JM; Mahle, DA; Greene, RJ; et al. (1993) Variability of physiologically-based

pharmacokinetic (PB-PK) model parameters and their effects on PB-PK model predictions in a

risk assessment for perchloroethylene. Toxicol Lett 68:131-144.

Giardino, NJ; Gumerman, E; Esmen, NA; et al. (1992) Shower volatilization exposures in

homes using tap water contaminated with TCE. J Exposure Analysis Environ Epidemiol (Suppl.

1):147-158.

Goodman, LS; Gilman, A, (eds.) (1975) The pharmacological basis of therapeutics, 5th ed. New

York: Macmillan Publishing Co., Inc.

Hazardous Substances Data Bank (HSDB). (1996) National Library of Medicine. National

Institutes of Health. Washington, DC: U.S. Department of Health and Human Services.

Howard, PH. (1993) Handbook of environmental fate and exposure data for organic chemicals,

vol. IV. Chelsea, MI: Lewis Publishers.
122

Howard, PH; Boethling, RS; Jarvis, WF; et al. (1991) Handbook of environmental degradation

rates. Chelsea, MI: Lewis Publishers.

International Agency for Research on Cancer (IARC). (1972-present) Monographs on the

evaluation of the carcinogenic risk of chemicals to man. Geneva: World Health Organization,

International Agency for Research on Cancer. 

IARC. (1995) IARC monographs on the evaluation of carcinogenic risks to humans: dry

cleaning, some chlorinated solvents and other industrial chemicals. Vol. 63. Lyon, France:

IARC.

ITII. (1982) Toxic and hazardous industrial chemicals safety manual. Tokyo: The International

Technical Information Instsitute.

Kirk-Othmer Encyclopedia of Chemical Technology. (1978-84) 3rd ed., volumes 1-26. New

York: John Wiley and Sons.

Kuney, JH; Nullican, JN. (eds.) (1988) Chemcyclopedia. Washington, DC: American Chemical

Society. 

Ligocki, MP; Leuenberger, C; Pankow, JF. (1985) Trace organic compounds in rain-II. Gas

scavenging of neutral organic compounds. Atmos Environ 19:1609-1617.

The Merck Index. (1983) 10th ed. Rahway, NJ: Merck Co., Inc.

The Merck Index. (1989) 11th ed. Rahway, NJ: Merck Co., Inc.

NAS (National Academy of Sciences). (1991) Who breastfeeds in the United States. In:

Nutrition during lactation. Washington, DC: National Academy Press.

National Fire Protection Association. (1986) Fire protection guide on hazardous materials, 9th

ed. Boston: National Fire Protection Association.

National Research Council (NRC). (1977) Drinking water and health, vol 1. Washington, DC:

National Academy Press.

NHANES III. (July 1997) Written communication from Dr. David Ashley of CDC on levels of

VOCs in blood.

NIOSH. (1976) NIOSH criteria document;1,1,1-trichloroethane. Washington, DC: U.S.

Department of Health, Education and Welfare. Pub. No. 76-184.

Osol, A. (ed.) (1980) Remington’s pharmaceutical science, 16th ed. Easton, PA: Mack

Publishing Co.
123

Pfleger, K; Maurer, H; Weber, A. (1985) Mass spectral and GC data of drugs, poisons and their

metabolites. Deerfield Beach, FL: VCR Publishers.

Reynolds, JEF; Prasad, AB. (eds.) (1982) Martindale—the extra pharmacopoeia, 28th ed. 

London: The Pharmaceutical Press.

Riddick, JA; Bunger, WB; Sakano, TK. (1985) Techniques of chemistry, 4th ed., vol II. Organic

solvents. New York: John Wiley and Sons.

Riddick, JA; et al. (1986) Organic solvents: physical properties and methods of purification. In:

Techniques of chemistry, 4th ed. New York: Wiley-Interscience. 

Sabel, GV; Clark, TP. (1984) Volatile organic compounds as indicators of municipal solid waste

leachate contamination. Waste Manage Res 2:119-130.

Sax, NI. (1984) Dangerous properties of industrial materials, 6th ed. New York: Van Nostrand

Reinhold Co.

Sax, NI; Lewis, RJ, Sr. (eds.) (1987) Hawley’s condensed chemical dictionary, 11th ed. New

York: Van Nostrand Reinhold Co.

Sittig, M. (1985) Handbook of toxic and hazardous chemicals and carcinogens, 2nd ed. Park

Ridge, NJ: Noyes Data Corporation.

SRI. (1979) Assessment of human exposures to atmospheric perchloroethylene. U.S. EPA

Contract No. 68-02-2835.

Stewart, RD; Gay, HH; Schaffer, AW; et al. (1969) Experimental human exposure to methyl

chloroform vapor. Arch Environ Health 19(4):467-472.

U.S. Bureau of the Census. (1985) U.S. imports for the consumption and general imports. 

Washington, DC: U.S. Bureau of the Census.

U.S. Bureau of the Census. (1986) U.S. imports for the consumption and general imports. 

Washington, DC: U.S. Bureau of the Census.

U.S. Coast Guard. (1984-85) CHRIS - Hazardous chemical data. Volume II. Washington, DC:

U.S. Government Printing Office.

U.S. Environmental Protection Agency (U.S. EPA). (1980) Innovative alternative technology

assessment manual. Washington, DC: U.S. Environmental Protection Agency.

U.S. EPA. (1981a) Treatability manual. EPA/600/2-82-001A.

U.S. EPA. (1981b) Engineering handbook for hazardous waste incineration. EPA/68-03-3025. 

Washington, DC; pp. 3-15.
124

U.S. EPA. (1982a) Management of hazardous waste leachate. EPA Contract No. 68-03-2766. 

Washington, DC.

U.S. EPA. (1982b) STORET database. Office of Water. Washington, DC: U.S. Environmental

Protection Agency.

U.S. EPA. (1987) The Total Exposure Assessment Methodology (TEAM) study: summary and

analysis: volume 1, EPA/600/6-87/002a.

U.S. EPA. (1994) Final draft for the drinking water criteria document on chlorinated acids/

aldehydes/ketones/alcohols. Office of Water, Health and Ecological Criteria Division.

Washington, DC: U.S. Environmental Protection Agency.

U.S. EPA. (1995) The National Public Water Systems Supervision Program. The FY 1994

Compliance Report. Office of Water. EPA 812-R-94-001. Washington, DC: U.S. Environmental Protection Agency.

U.S. EPA. (1996a) Toxic release inventory. Washington, DC: U.S. Environmental Protection

Agency.

U.S. EPA. (1996b) SIDS data summary for chloroacetic acid. January 31, 1996. Draft

summary. Office of Pollution and Toxic Substances. Washington, DC: U.S. Environmental

Protection Agency.

U.S. EPA. (1998) EPA data file. Office of Groundwater and Drinking Water. Washington,

DC: U.S. Environmental Protection Agency.

U.S. EPA. (1999a) AIRSDATA. EPA Internet. http://www.epa.gov/airsdata/. Office of Air

Quality Planning & Standards. Research Triangle Park, NC. 

U.S. EPA. (1999b) Cumulative Exposure Project (CEP). EPA Internet. www.epa.gov/

cumulativeexposure/air/air.htm.

USITC. (1981) Chemical products synopsis. Washington, DC: U.S. Interantional Trade

Commision.

USITC. (1985) Chemical products synopsis. Washington, DC: U.S. Interantional Trade

Commision.

Vershueren, K. (1983) Handbook of environmental data of organic chemicals, 2nd ed. New

York: Van Nostrand Reinhold Co.

Wallace, LA; Pellizzari, ED; Hartwell, TC. (1985) Personal exposures, indoor-outdoor

relationships and breath levels of toxic air pollutants measured for 355 persons in New Jersey. 

Atmos Environ 19:1651-1661.
125

Weast, RC. (1979) Handbook of chemistry and physics, 60th ed. Boca Raton, FL: CRC Press,

Inc.

Weast, RC. (1987-88) Handbook of chemistry and physics, 68th ed. Boca Raton, FL: CRC Press,

Inc.

WHO. (1983) Environmental health criteria: trichloroethylene. Geneva, Switzerland: World

Health Organization.