PEER REVIEW DRAFT - DO NOT CITE OR QUOTE
Draft Risk Evaluation
for N-Methylpyrrolidone
(2-Pyrrolidinone, 1 Methyl-) (NMP)
Supplemental Information on
Occupational Exposure Assessment
xvEPA
United States
Environmental Protection Agency
Office of Chemical Safety and
Pollution Prevention
CASRN: 872-50-4
October 2019
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TABLE OF CONTENTS
ABBREVIATIONS 12
1 INTRODUCTION 15
1.1 Overview 15
1.2 Scope 15
1.3 Components of the Occupational Exposure Assessment 18
1.4 Approach and Methodology for Occupational Exposures 19
1.4.1 Process Description 19
1.4.2 Number of Sites, Workers, and ONUs 19
1.4.3 PBPK Input Parameter Determination 20
1.4.3.1 General Approach 21
1.4.3.2 Approach for thi s Ri sk Evaluati on 22
1.4.3.2.1 Weight Fraction of NMP 23
1.4.3.2.2 Skin Surface Area 23
1.4.3.2.3 Glove Usage 23
1.4.3.2.4 Duration of Dermal Contact 25
1.4.3.2.5 Air Concentration for Inhalation and Vapor-through-Skin Exposure 25
1.4.3.2.6 Body Weight 26
2 ENGINEERING ASSESSMENT 27
2.1 Manufacturing 27
2.1.1 Process Description 27
2.1.2 Exposure Assessment 28
2.1.2.1 Worker Activities 28
2.1.2.2 Number of Potentially Exposed Workers 28
2.1.2.3 Occupational Exposure Assessment Methodology 30
2.1.2.3.1 Inhalation 30
2.1.2.3.2 Dermal 31
2.1.3 PBPK Inputs 32
2.1.4 Summary 33
2.2 Repackaging 33
2.2.1 Process Description 33
2.2.2 Exposure Assessment 33
2.2.2.1 Worker Activities 33
2.2.2.2 Number of Potentially Exposed Workers 34
2.2.2.3 Occupational Exposure Assessment Methodology 35
2.2.2.3.1 Inhalation 36
2.2.2.3.2 Dermal 37
2.2.3 PBPK Inputs 38
2.2.4 Summary 39
2.3 Chemical Processing, Excluding Formulation 39
2.3.1 Process Description 39
2.3.1.1 Agricultural Chemical Manufacturing 39
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2.3.1.2 Petrochemical Manufacturing 39
2.3.1.3 Pharmaceutical Manufacturing 40
2.3.1.4 Polymer Manufacturing 41
2.3.1.5 Miscellaneous 41
2.3.2 Exposure Assessment 42
2.3.2.1 Worker Activities 42
2.3.2.2 Number of Potentially Exposed Workers 42
2.3.2.3 Occupational Exposure Assessment Methodology 46
2.3.2.3.1 Inhalation 46
2.3.2.3.2 Dermal 47
2.3.3 PBPK Inputs 48
2.3.4 Summary 48
2.4 Incorporation into Formulation, Mixture, or Reaction Product 48
2.4.1 Process Description 48
2.4.2 Exposure Assessment 49
2.4.2.1 Worker Activities 49
2.4.2.2 Number of Potentially Exposed Workers 50
2.4.2.3 Occupational Exposure Assessment Methodology 53
2.4.2.3.1 Inhalation 53
2.4.2.3.2 Dermal 54
2.4.3 PBPK Inputs 55
2.4.4 Summary 56
2.5 Metal Finishing 57
2.5.1 Process Description 57
2.5.2 Exposure Assessment 57
2.5.2.1 Worker Activities 57
2.5.2.2 Number of Potentially Exposed Workers 58
2.5.2.3 Occupational Exposure Assessment Methodology 60
2.5.2.3.1 Inhalation 60
2.5.2.3.2 Dermal 61
2.5.3 PBPK Inputs 62
2.5.4 Summary 63
2.6 Removal of Paints, Coatings, Adhesives, and Sealants 63
2.6.1 Process Description 63
2.6.2 Exposure Assessment 64
2.6.2.1 Worker Activities 64
2.6.2.2 Number of Potentially Exposed Workers 64
2.6.2.3 Occupational Exposure Assessment Methodology 65
2.6.2.3.1 Inhalation 65
2.6.2.3.2 Dermal 66
2.6.3 PBPK Inputs 67
2.6.4 Summary 69
2.7 Application of Paints, Coatings, Adhesives, and Sealants 69
2.7.1 Process Description 69
2.7.2 Exposure Assessment 69
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2.7.2.1 Worker Activities 70
2.7.2.2 Number of Potentially Exposed Workers 70
2.7.2.3 Occupational Exposure Assessment Methodology 74
2.7.2.3.1 Inhalation 74
2.7.2.3.2 Dermal 75
2.7.3 PBPK Inputs 76
2.7.4 Summary 78
2.8 Electronic Parts Manufacturing 78
2.8.1 Process Description 78
2.8.2 Exposure Assessment 79
2.8.2.1 Worker Activities 79
2.8.2.2 Number of Potentially Exposed Workers 80
2.8.2.3 Occupational Exposure Assessment Methodology 81
2.8.2.3.1 Inhalation 81
2.8.2.3.2 Dermal 83
2.8.3 PBPK Inputs 84
2.8.4 Summary 86
2.9 Printing and Writing 86
2.9.1 Process Description 86
2.9.2 Exposure Assessment 87
2.9.2.1 Worker Activities 87
2.9.2.2 Number of Potentially Exposed Workers 87
2.9.2.3 Occupational Exposure Assessment Methodology 88
2.9.2.3.1 Inhalation 88
2.9.2.3.2 Dermal 89
2.9.3 PBPK Inputs 90
2.9.4 Summary 91
2.10 Soldering 91
2.10.1 Process Description 91
2.10.2 Exposure Assessment 92
2.10.2.1 Worker Activities 92
2.10.2.2 Number of Potentially Exposed Workers 92
2.10.2.3 Occupational Exposure Assessment Methodology 93
2.10.2.3.1 Inhalation 93
2.10.2.3.2 Dermal 94
2.10.3 PBPK Inputs 94
2.10.4 Summary 95
2.11 Commercial Automotive Servicing 95
2.11.1 Process Description 95
2.11.2 Exposure Assessment 96
2.11.2.1 Worker Activities 96
2.11.2.2 Number of Potentially Exposed Workers 97
2.11.2.3 Occupational Exposure Assessment Methodology 98
2.11.2.3.1 Inhalation 98
2.11.2.3.2 Dermal 99
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2.11.3 PBPK Inputs 100
2.11.4 Summary 101
2.12 Laboratory Use 101
2.12.1 Process Description 101
2.12.2 Exposure Assessment 102
2.12.2.1 Worker Activities 102
2.12.2.2 Number of Potentially Exposed Workers 102
2.12.2.3 Occupational Exposure Assessment Methodology 103
2.12.2.3.1 Inhalation 103
2.12.2.3.2 Dermal 104
2.12.3 PBPK Inputs 105
2.12.4 Summary 105
2.13 Cleaning 105
2.13.1 Process Description 105
2.13.1.1 Aerosol Degreasing 106
2.13.1.2 Dip Degreasing and Cleaning 106
2.13.1.3 Wipe Cleaning, Including Use of Spray-Applied Cleaning Products 106
2.13.2 Exposure Assessment 107
2.13.2.1 Worker Activities 107
2.13.2.2 Number of Potentially Exposed Workers 107
2.13.2.3 Occupational Exposure Assessment Methodology 108
2.13.2.3.1 Inhalation 108
2.13.2.3.2 Dermal 109
2.13.3 PBPK Inputs 110
2.13.4 Summary Ill
2.14 Fertilizer Application Ill
2.14.1 Process Description Ill
2.14.2 Exposure Assessment 112
2.14.2.1 Worker Activities 112
2.14.2.2 Number of Potentially Exposed Workers 113
2.14.2.3 Occupational Exposure Assessment Methodology 113
2.14.2.3.1 Inhalation 113
2.14.2.3.2 Dermal 114
2.14.3 PBPK Inputs 115
2.14.4 Summary 116
2.15 Wood Preservatives 116
2.15.1 Process Description 116
2.15.2 Exposure Assessment 116
2.15.2.1 Worker Activities 116
2.15.2.2 Number of Potentially Exposed Workers 117
2.15.2.3 Occupational Exposure Assessment Methodology 117
2.15.2.3.1 Inhalation 117
2.15.2.3.2 Dermal 118
2.15.3 PBPK Inputs 119
2.15.4 Summary 120
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2.16 Recycling and Disposal 120
2.16.1 Process Description 120
2.16.2 Exposure Assessment 123
2.16.2.1 Worker Activities 123
2.16.2.2 Number of Potentially Exposed Workers 124
2.16.2.3 Occupational Exposure Assessment Methodology 125
2.16.2.3.1 Inhalation 125
2.16.2.3.2 Dermal 126
2.16.3 PBPK Inputs 127
2.16.4 Summary 128
3 DISCUSSION OF RESULTS 129
3.1 Variability 129
3.2 Uncertainties and Limitations 129
3.2.1 Number of Workers 129
3.2.2 PBPK Input Parameters 129
3.2.2.1 Tank Truck and Railcar Loading and Unloading Release and Inhalation Exposure
Model 131
3.2.2.2 Drum Loading and Unloading Release and Inhalation Exposure Model 131
3.2.2.3 Model for Occupational Exposures during Aerosol Degreasing of Automotive Brakes
131
3.2.2.4 Near-Field/Far-Field Model Framework 132
REFERENCES 133
APPENDICES 141
Appendix A Inhalation Data for Each Occupational Scenario 141
A.l Manufacturing 141
A.2 Repackaging......... .146
A.3 Chemical Processing, Excluding Formulation............... ..........146
A.4 Incorporation into Formulation, Mixture, or Reaction Product ......153
A.5 Metal Finishing ..160
A.6 Removal of Paints, Coatings, Adhesives, and Sealants .....163
A.7 Application of Paints, Coatings, Adhesives, and Sealants.......................... 167
A.8 Electronic Parts Manufacturing............ ......172
A.9 Printing and Writing....... ..178
A. 10 Soldering ..................182
A. 11 Commercial Automotive Servicing .......................184
A.'12 Laboratory use.......... ............185
A. 13 Cleaning .187
A.14 Fertilizer Application .........191
A. 15 Wood Preservatives... .....,,,.....,...193
A. 16 Recycling and Disposal.... [[[195
Appendix B Description of Models used to Estimate Worker and ONU Exposures 197
B.l Approaches for Estimating Number of Workers...... ...197
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B.2.1 Displacement of Saturated Air Inside Tank Trucks and Railcars 202
B.2.2 Emissions of Saturated Air that Remain in Transfer Hoses/Loading Arm 203
B.2.3 Emission from Leaks 204
B.2.3.1 Exposure Estimates 207
B.3 Dram Loading and Unloading Release and Inhalation Exposure Model Approach and
Parameters... 210
B.4 Model Air Release and Inhalation Exposure Equations 210
B. 5 Number of Containers and Short-T erm Exposure Duration Equations ....212
B.6 Model Input Parameters 213
B.7 Monte Carlo Simulation Results ...............214
B.8 Brake Servicing Near-Field/Far-Field Inhalation Exposure Model Approach and Parameters216
B.8.1 Model Design Equations 216
B.8.2 Model Parameters 222
B.8.2.1 Far-Field Volume 225
B.8.2.2 Air Exchange Rate 225
B.8.2.3 Near-Field Indoor Air Speed 225
B.8.2.4 Near-Field Volume 226
B.8.2.5 Application Time 226
B.8.2.6 Averaging Time 226
B.8.2.7 NMP Weight Fraction 226
B.8.2.8 Volume of Degreaser Used per Brake Job 227
B.8.2.9 Number of Applications per Brake Job 227
B.8.2.10 Amount of NMP Used per Application 227
B.8.2.11 Operating Hours per Week 227
B.8.2.12 Number of Brake Jobs per Work Shift 227
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LIST OF TABLES
Table 1-1. Crosswalk of Conditions of Use Listed to Occupational Exposure Scenarios Assessed in the
Risk Evaluation 16
Table 1-2. Glove Protection Factors for Different Dermal Protection Strategies from ECETOC TRA v3
24
Table 2-1. US Number of Establishments and Employees for Manufacturing 29
Table 2-2. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Manufacturing 30
Table 2-3. Summary of Parameters for Worker Dermal Exposure to Liquids During Manufacturing.... 32
Table 2-4. Characterization of PBPK Model Input Parameters for Manufacturing of NMP 32
Table 2-5. PBPK Model Input Parameters for Manufacturing of NMP 33
Table 2-6. US Number of Establishments and Employees for Repackaging 35
Table 2-7. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure Repackaging 36
Table 2-8. Summary of Parameters for Worker Dermal Exposure to Liquids During Repackaging 38
Table 2-9. Characterization of PBPK Model Input Parameters for Repackaging 38
Table 2-10. PBPK Model Input Parameters for Repackaging 39
Table 2-11. US Number of Establishments and Employees for Chemical Processing, Excluding
Formulation 44
Table 2-12. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Chemical Processing, Excluding Formulation 46
Table 2-13. Summary of Parameters for Worker Dermal Exposure to Liquids During Chemical
Processing, Excluding Formulation 47
Table 2-14. Characterization of PBPK Model Input Parameters for Chemical Processing, Excluding
Formulation 48
Table 2-15. PBPK Model Input Parameters for Chemical Processing, Excluding Formulation 48
Table 2-16. US Number of Establishments and Employees for Incorporation into Formulation, Mixture,
or Reaction Product 51
Table 2-17. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Incorporation into Formulation, Mixture, or Reaction Product 53
Table 2-18. Summary of Area Monitoring During Incorporation into Formulation, Mixture, or Reaction
Product 54
Table 2-19. Summary of Parameters for Worker Dermal Exposure to Liquids During Incorporation into
Formulation, Mixture, or Reaction Product 55
Table 2-20. Characterization of PBPK Model Input Parameters for Incorporation into Formulation,
Mixture, or Reaction Product 56
Table 2-21. PBPK Model Input Parameters for Incorporation into Formulation, Mixture, or Reaction
Product 56
Table 2-22. US Number of Establishments and Employees for Metal Finishing 59
Table 2-23. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During Metal
Finishing 60
Table 2-24. Summary of Area Monitoring During Metal Finishing 61
Table 2-25. Summary of Parameters for Worker Dermal Exposure to Liquids During Metal Finishing 62
Table 2-26. Characterization of PBPK Model Input Parameters for Metal Finishing 62
Table 2-27. PBPK Model Input Parameters for Metal Finishing 62
Table 2-28. US Number of Establishments and Employees for Removal of Paints, Coatings, Adhesives,
and Sealants 65
Table 2-29. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Removal of Paints, Coatings, Adhesives, and Sealants 66
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Table 2-30. Summary of Parameters for PBPK Modeling of Worker Dermal Exposure to Liquids During
Removal of Paints, Coatings, Adhesives, and Sealants 67
Table 2-31. Characterization of PBPK Model Input Parameters for Removal of Paints, Coatings,
Adhesives, and Sealants 68
Table 2-32. PBPK Model Input Parameters for Removal of Paints, Coatings, Adhesives, and Sealants 68
Table 2-33. US Number of Establishments and Employees for Application of Paints, Coatings,
Adhesives, and Sealants 72
Table 2-34. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Application of Paints, Coatings, Adhesives, and Sealants 74
Table 2-35. Summary of Occupational Non-User Inhalation Exposure During Application of Paints,
Coatings, Adhesives, and Sealants 75
Table 2-36. Summary of Parameters for Worker Dermal Exposure to Liquids During Application of
Paints, Coatings, Adhesives, and Sealants 76
Table 2-37. Characterization of PBPK Model Input Parameters for Application of Paints, Coatings,
Adhesives, and Sealants 77
Table 2-38. PBPK Model Input Parameters for Application of Paints, Coatings, Adhesives, and Sealants
77
Table 2-39. US Number of Establishments and Employees for Electronic Parts Manufacturing 80
Table 2-40. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Electronic Parts Manufacturing 82
Table 2-41. Summary of Area Monitoring During Electronic Parts Manufacturing 83
Table 2-42. Summary of Parameters for Worker Dermal Exposure During Electronic Parts
Manufacturing 84
Table 2-43. Characterization of PBPK Model Input Parameters for Electronic Parts Manufacturing 85
Table 2-44. PBPK Model Input Parameters for Electronic Parts Manufacturing 85
Table 2-45. US Number of Establishments and Employees for Printing and Writing 88
Table 2-46. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Printing and Writing 89
Table 2-47. Summary of Parameters for Worker Dermal Exposure to Liquids During Printing and
Writing 90
Table 2-48. Characterization of PBPK Model Input Parameters for Printing and Writing 91
Table 2-49. PBPK Model Input Parameters for Printing and Writing 91
Table 2-50. US Number of Establishments and Employees for Soldering 93
Table 2-51. Summary of Parameters for Worker Dermal Exposure During Soldering 94
Table 2-52. Characterization of PBPK Model Input Parameters for Soldering 95
Table 2-53. PBPK Model Input Parameters for Soldering 95
Table 2-54. US Number of Establishments and Employees for Commercial Automotive Servicing 97
Table 2-55. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Commercial Automotive Servicing 99
Table 2-56. Summary of Occupational Non-User Inhalation Exposure During Commercial Automotive
Servicing 99
Table 2-57. Summary of Parameters for Worker Dermal Exposure to Liquids During Commercial
Automotive Servicing 100
Table 2-58. Characterization of PBPK Model Input Parameters for Commercial Automotive Servicing
101
Table 2-59. PBPK Model Input Parameters for Commercial Automotive Servicing 101
Table 2-60. US Number of Establishments and Employees for Laboratory Use 103
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Table 2-61. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Laboratory Use 103
Table 2-62. Summary of Parameters for Worker Dermal Exposure During Laboratory Use 104
Table 2-63. Characterization of PBPK Model Input Parameters by Laboratory Use 105
Table 2-64. PBPK Model Input Parameters for Laboratory Use 105
Table 2-65. US Number of Establishments and Employees for Cleaning 108
Table 2-66. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Cleaning 108
Table 2-67. Summary of Parameters for Worker Dermal Exposure to Liquids During Cleaning 110
Table 2-68. Characterization of PBPK Model Input Parameters for Cleaning 110
Table 2-69. PBPK Model Input Parameters for Cleaning Ill
Table 2-70. U.S. Number of Establishments and Employees for Fertilizer Application 113
Table 2-71. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Fertilizer Application 114
Table 2-72. Summary of Parameters for Worker Dermal Exposure During Fertilizer Application 115
Table 2-73. Characterization of PBPK Model Input Parameters for Fertilizer Application 115
Table 2-74. PBPK Model Input Parameters for Fertilizer Application 116
Table 2-75. US Number of Establishments and Employees for Industries Using Wood Preservatives. 117
Table 2-76. Summary of Parameters for Wood Preservatives 118
Table 2-77. Summary of Parameters for Worker Dermal Exposure to Wood Preservatives 119
Table 2-78. Characterization of PBPK Model Input Parameters for Wood Preservatives 119
Table 2-79. PBPK Model Input Parameters for Wood Preservatives 119
Table 2-80. US Number of Establishments and Employees for Recycling and Disposal 124
Table 2-81. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Recycling and Disposal 126
Table 2-82. Summary of Parameters for Worker Dermal Exposure During Recycling and Disposal... 127
Table 2-83. Characterization of PBPK Model Input Parameters for Recycle and Disposal 127
Table 2-84. PBPK Model Input Parameters for Recycle and Disposal 128
TableApx A-l. Summary of Inhalation Monitoring Data for Manufacturing 143
TableApx A-2. Summary of Inhalation Monitoring Data for Chemical Processing, Excluding
Formulation 148
Table Apx A-3. Summary of Inhalation Monitoring Data for Incorporation into Formulation, Mixture,
or Reaction Product 155
Table Apx A-4. Summary of Parameters for Worker Inhalation Exposure Concentrations During Metal
Finishing 161
Table Apx A-5. Summary of Inhalation Monitoring Data for Removal of Paints, Coatings, Adhesives,
and Sealants 164
Table Apx A-6. Summary of Inhalation Monitoring Data for Application of Paints, Coatings,
Adhesives, and Sealants 169
Table_Apx A-7. Summary of SIA Data SIA (SIA, 2019a) 174
Table Apx A-8. Summary of Worker Inhalation Exposure Concentrations During Electronics
Manufacturing 175
Table Apx A-9. Summary of Parameters for Worker Inhalation Exposure Concentrations During
Printing and Writing 180
Table Apx A-10. Summary of Inhalation Exposure Concentrations During Soldering 183
Table_Apx A-l 1. Aerosol Degreasing Model Results 184
Table Apx A-12. Summary of Inhalation Monitoring Data for Laboratory Use 186
TableApx A-13. Summary of Inhalation Monitoring Data for Cleaning 188
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TableApx A-14. Summary of Worker Inhalation Exposure Concentrations During Fertilizer
Application 192
TableApx A-15. Summary of Worker Inhalation Exposure Concentrations During Use of Wood
Preservatives 194
Table Apx A-16. 2016 TRI Off-Site Transfers for NMP 195
TableApx B-l. SOCs with Worker and ONU Designations for All Conditions of Use Except Dry
Cleaning 198
Table Apx B-2. SOCs with Worker and ONU Designations for Dry Cleaning Facilities 198
Table_Apx B-3. Estimated Number of Potentially Exposed Workers and ONUs under NAICS 812320
199
Table Apx B-4. Example Dimension and Volume of Loading Arm/Transfer System 204
Table Apx B-5. Default Values for Calculating Emission Rate of N-Methylpyrrolidone from
Transfer/Loading Arm 204
Table Apx B-6. Parameters for Calculating Emission Rate of N-Methylpyrrolidone from Equipment
Leaks 205
Table_Apx B-7. Default Values for Fa and N 206
Table Apx B-8. Parameters for Calculating Exposure Concentration Using the EPA/OPPT Mass
Balance Model 208
Table Apx B-9. Calculated Emission Rates and Resulting Exposures of N-Methylpyrrolidone from the
Tank Truck and Railcar Loading and Unloading Release and Inhalation Exposure Model
209
Table Apx B-10. Summary of Parameter Values and Distributions Used in the Inhalation Exposure
Model 213
Table Apx B-l 1. Drum Loading and Unloading Inhalation Exposure Simulation Results 215
Table Apx B-12. Summary of Parameter Values and Distributions Used in the Brake Servicing Near-
Field/Far-Field Inhalation Exposure Model 223
LIST OF FIGURES
Figure 2-1. NMP Manufacturing Under Adiabatic Conditions 27
Figure 2-2. NMP Manufacturing Using Gamma-Butyrolactone (GBL) and Monomethylamine (MMA)27
Figure 2-3. General Process Flow Diagram for Repackaging 33
Figure 2-4. Typical Waste Disposal Process (U.S. EPA, 2017a) 121
Figure 2-5. Typical Industrial Incineration Process 122
FigureApx B-l. Illustration of Transfer Lines Used During Tank Truck Unloading and Associated
Equipment Assumed by EPA 207
Figure Apx B-2. Graphical Probability Density Function of Monte Carlo Simulation Results 215
Figure Apx B-3. The Near-Field/Far-Field Model as Applied to the Brake Servicing Near-Field/Far-
Field Inhalation Exposure Model 217
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ABBREVIATIONS
ACGIH
American Conference of Government Industrial Hygienists
AIA
Aerospace Industries Association
AIHA
American Industrial Hygiene Association
AP-42
Compilation of Air Pollutant Emissions Factors
APF
Assigned Protection Factor
BLS
Bureau of Labor Statistics
CAA
Clean Air Act
CARB
California Air Resources Board
CASRN
Chemical Abstracts Service Registry Number
CBI
Confidential Business Information
CDR
Chemical Data Reporting
CFR
Code of Federal Regulations
cm2
Centimeters squared
CSPA
Consumer Specialty Products Association
DOD
Department of Defense
DOEHRS-IH
Defense Occupational and Environmental Health Readiness System
Industrial Hygiene
ECETOC
European Center for Ecotoxicology and Toxicology of Chemicals
ECHA
European Chemicals Agency
EPA
Environmental Protection Agency
EPCRA
Emergency Planning and Community Right-to-Know Act
ESD
Emission Scenario Documents
EU
European Union
EVOH
Ethylene vinyl alcohol (gloves)
FDA
Food and Drug Administration
FFEM
FUJTFILM Electronic Materials
FIFRA
Federal Insecticide, Fungicide and Rodenticide Act
FR
Federal Register
g
grams
GBL
Gamma-buty rol actone
GS
Generic Scenario
HERO
Health & Environmental Research Online
HHE
Health Hazard Evaluation
hr
Hour
HVLP
High-Volume Low-Pressure
IBC
Intermediate bulk container
IFA
German Institute for Occupational Safety and Health
kg
Kilogram(s)
kPa
kilopascal
L
Liter(s)
lb
Pound
LEV
Local Exhaust Ventilation
LPG
Liquefied Petroleum Gas
m3
Cubic Meter(s)
MEM A
Motor & Equipment Manufacturers Association
mg
Milligram(s)
MMA
Monomethylamine
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mmHg
Millimeter(s) of Mercury
s
Seconds
SDS
Safety Data Sheet
NABTU
North America's Building Trades Unions
NAICS
North American Industry Classification System
NEMA
National Electrical Manufacturers Association
NICNAS
National Industrial Chemicals Notification and Assessment Scheme
NIOSH
National Institute of Occupational Safety and Health
NKRA
Not Known or Reasonably Ascertainable
NMP
N-Methylpyrrolidone
NPDES
National Pollutant Discharge Elimination System
OAQPS
Office of Air Quality Planning and Standards
OARS
Occupational Alliance for Risk Science
OECD
Organisation for Economic Co-operation and Development
OEL
Occupational Exposure Limit
OES
Occupational Exposure Scenario
ONU
Occupational Non-User
OPPT
Office of Pollution Prevention and Toxics
OSHA
Occupational Safety and Health Administration
PBPK
Physiologically Based Pharmacokinetic (Modeling)
PBZ
Personal Breathing Zone
PEL
Permissible Exposure Limit
PF
Problem Formulation
POTW
Publicly Owned Treatment Works
PNOR
Particulates Not Otherwise Regulated
PPE
Personal Protective Equipment
ppm
Part(s) per Million
PPS
Polyphenylene Sulfide
QC
Quality Control
RA
Risk Assessment
RCRA
Resource Conservation and Recovery Act
RDF
Refuse-Derived Fuel
REL
Recommended Exposure Limit
RIVM
The Netherlands' National Institute for Public Health and the Environment
SDS
Safety Data Sheet
SDWA
Safe Drinking Water Act
SIA
Semiconductor Industry Association
SOC
Standard Occupational Classification
SOCMI
Synthetic Organic Chemical Manufacturing Industry
SUSB
Statistics of U.S. Businesses
TLV
Threshold Limit Value
TRA
Targeted Risk Assessment (tool)
TRI
Toxics Release Inventory
TSCA
Toxic Substances Control Act
TWA
Time-Weighted Average
U.S.
United States
UV
Ultraviolet
USD A
U.S. Department of Agriculture
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VOC Volatile Organic Compound
WEEL Workplace Environment Exposure Limit
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1 INTRODUCTION
This document supports occupational exposure assessment in the "Risk Evaluation for N-
Methylpyrrolidone (2-Pyrrolidinone, 1 Methyl-) (NMP)."
1.1 Overview
For the purpose of this assessment, EPA considered occupational exposure of the total workforce of
exposed users and non-users, which include but are not limited to male and female workers of
reproductive age who are >16 years of age. Female workers of reproductive age are >16 to less than 50
years old. Adolescents (>16 to <21 years old) are a small part of this total workforce. The occupational
exposure assessment is applicable to and covers the entire workforce who are exposed to NMP.
EPA evaluated acute and chronic exposures to workers and occupational non-users (ONUs) by dermal
and inhalation routes in association with NMP use in industrial and commercial applications, which are
shown in Table 1-1. Oral exposure via incidental ingestion of inhaled vapor/mist/dust will be considered
as discussed in the "Risk Evaluation for N-Methylpyrrolidone (2-Pyrrolidinone, 1 Methyl-) (NMP)."
EPA assessed these exposures by inputting exposure parameters into a physiologically based
pharmacokinetic (PBPK) model, which is described in Appendix I of the Risk Evaluation document.
Parameter development for each occupational exposure scenario assessed are described in Section 2.
For each scenario, EPA distinguishes exposures for workers and ONUs when possible. Normally, a
primary difference between workers and ONUs is that workers may handle chemical substances and
have direct dermal contact with liquid chemicals that they handle, while ONUs are working in the
general vicinity of workers but do not handle the assessed chemical substances and do not have direct
dermal contact with liquid chemicals being handled by the workers. EPA expects that ONUs may often
have lower inhalation exposures than workers since they may be further from the exposure source than
workers. For inhalation, if EPA cannot distinguish ONU exposures from workers, EPA assumes that
ONU inhalation may be less than the inhalation estimates for workers.
1.2 Scope
Workplace exposures have been assessed for the following industrial and commercial uses of NMP, also
referred to as occupational exposure scenarios (OES):
1. Manufacturing
2. Repackaging
3. Chemical Processing, Excluding Formulation
4. Incorporation into a Formulation, Mixture or Reaction Product
5. Application of Paints, Coatings, Adhesives and Sealants
6. Printing and Writing
7. Metal Finishing
8. Removal of Paints, Coatings, Adhesives, and Sealants
9. Cleaning
10. Automotive Car Servicing
11. Laboratory Use
12. Electronics Manufacturing
13. Soldering
14. Fertilizer Application
15. Wood Preservatives
16. Recycling and Disposal
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These are mapped to the conditions of use listed in the Risk Evaluation document in the table below.
Table 1-1. Crosswalk of Conditions of Use Listed to Occupational Exposure Scenarios Assessed in
the Risk Evaluation
l.ilV ( \cle
S(;i»e
Csili'Sion ;|
Siil)Cii(e}i»r\ h
Occupiilioiiiil l.\|)(isui o
Smi;iri»
Manufacture
Domestic
Manufacture
Domestic Manufacture
Section 2.1 - Manufacturing
Import
Import
Section 2.2 - Repackaging
Processing as a
reactant or
intermediate
Intermediate in Plastic Material and Resin
Manufacturing and in Pharmaceutical and Medicine
Manufacturing
Section 2.3 - Chemical
Processing, Excluding
Formulation
Other
Adhesives and sealant chemicals in Adhesive
Manufacturing
Anti-adhesive agents in Printing and Related Support
Activities
Processing
Paint additives and coating additives not described by
other codes in Paint and Coating Manufacturing; and
Print Ink Manufacturing
Incorporated into
formulation,
mixture or
reaction product
Processing aids not otherwise listed in Plastic Material
and Resin Manufacturing
Section 2.4 - Incorporation
into Formulation, Mixture,
Manufacturing; Primary Metal Manufacturing; Soap,
Cleaning Compound and Toilet Preparation
Manufacturing; Transportation Equipment
Manufacturing; All Other Chemical Product and
Preparation Manufacturing; Printing and Related
Support Activities; Services; Wholesale and Retail
Trade
or Reaction Product
Surface active agents in Soap, Cleaning Compound and
Toilet Preparation Manufacturing
Plating agents and surface treating agents in Fabricated
Metal Product Manufacturing
Processing
Incorporated into
formulation,
mixture or
reaction product
Solvents (which become part of product formulation or
mixture) in Electrical Equipment, Appliance and
Component Manufacturing; Other Manufacturing; Paint
and Coating Manufacturing; Print Ink Manufacturing;
Soap, Cleaning Compound and Toilet Preparation
Manufacturing; Transportation Equipment
Manufacturing; All Other Chemical Product and
Preparation Manufacturing; Printing and Related
Support Activities; Wholesale and Retail Trade
Section 2.4 - Incorporation
into Formulation, Mixture,
or Reaction Product
Other uses in Oil and Gas Drilling, Extraction and
Support Activities; Plastic Material and Resin
Manufacturing; Services
Incorporated into
article
Lubricants and lubricant additives in Machinery
Manufacturing
Section 2.5 - Metal
Finishing
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l.il'e ( \ck'
S(;i»o
C.iU'Sion ;|
Siil)Cii(e}i»r\ h
Occii|);ilion;il I'xposuro
SiTii.irio
Paint additives and coating additives not described by
other codes in Transportation Equipment
Manufacturing
Section 2.5 - Application of
Paints, Coatings, Adhesives,
and Sealants
Solvents (which become part of product formulation or
mixture), including in Textiles, Apparel and Leather
Manufacturing
Section 2.4 - Incorporation
into Formulation, Mixture,
or Reaction Product
Processing
Incorporated into
article
Other, including in Plastic Product Manufacturing
Section 2.3 - Chemical
Processing, Excluding
Formulation
Recycling
Recycling
Section 2.16 - Recycling and
Disposal
Repackaging
Wholesale and Retail Trade
Section 2.2 - Repackaging
Distribution in
commerce
Distribution
Distribution in commerce
Activities related to
distribution (e.g., loading,
unloading) are considered
throughout the life cycle,
rather than using a single
distribution scenario.
Paint and coating removers
Section 2.6 - Removal of
Paints and
Adhesive removers
Paints, Coatings, Adhesives,
and Sealants
coatings
Lacquers, stains, varnishes, primers and floor finishes
Powder coatings (surface preparation)
Section 2.7 - Application of
Paints, Coatings, Adhesives,
and Sealants
Industrial,
commercial,
and consumer
Paint additives
and coating
additives not
described by other
codes
Use in Computer and Electronic Product
Manufacturing, Construction, Fabricated Metal Product
Manufacturing, Machinery Manufacturing, Other
Manufacturing, Paint and Coating Manufacturing,
Primary Metal Manufacturing, Transportation
Equipment Manufacturing, Wholesale and Retail Trade
use
Solvents (for
cleaning or
degreasing)
Use in Electrical Equipment, Appliance and Component
Manufacturing.
Section 2.8 - Electronics
Manufacturing
Ink, toner, and
Printer ink
Section 2.9 - Printing and
colorant products
Inks in writing equipment
Writing
Processing aids,
specific to
petroleum
production
Petrochemical Manufacturing
Section 2.3 - Chemical
Processing, Excluding
Formulation
Industrial,
Adhesives and sealant chemicals including binding
agents
Section 2.7 - Application of
Paints, Coatings, Adhesives,
and Sealants
commercial,
and consumer
use
Adhesives and
sealants
Single component glues and adhesives, including
lubricant adhesives
Two-component glues and adhesives, including some
resins
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l.il'e ( \ck'
C.iU'Sion ;|
Siil)Cii(e}i»r\ h
Occii|);ilion;il I'xposuro
S(;i»e
SiTii.irio
Soldering materials
Section 2.10 - Soldering
Anti-freeze and de-icing products
Section 2.11- Commercial
Automotive Serving
Automotive care products
Lubricants and greases
Metal products not
Section 2.5 - Metal
covered elsewhere
Finishing
Laboratory chemicals
Section 2.12 - Laboratory
Use
Lithium ion batteries
Section 2.8 - Electronics
Manufacturing
Other uses
Cleaning and furniture care products, including wood
cleaners, gasket removers
Section 2.13 - Cleaning
Other uses in Oil and Gas Drilling, Extraction and
Support Activities
Section 2.3 - Chemical
Processing, Excluding
Formulation
Lubricant and lubricant additives, including hydrophilic
Section 2.5 - Metal
coatings
Finishing
Fertilizer and other agricultural chemical manufacturing
- processing aids and solvents
Section 2.14 - Fertilizer
Application
Pharmaceutical and Medicine Manufacturing -
functional fluids (closed systems)
Section 2.3 - Chemical
Processing, Excluding
Formulation
Wood preservatives
Section 2.15 - Wood
Preservatives
Industrial pre-treatment
Industrial wastewater treatment
Publicly owned treatment works (POTW)
Disposal
Disposal
Underground injection
Section 2.16 - Recycling and
Disposal
Landfill (municipal, hazardous or other land disposal)
Incinerators (municipal and hazardous waste)
Emissions to air
a These categories of conditions of use appear in the Life Cycle Diagram, reflect CDR codes, and broadly represent
conditions of use of NMP in industrial and/or commercial settings.
b These subcategories reflect more specific uses of NMP
1.3 Components of the Occupational Exposure Assessment
The occupational exposure assessment of each use comprises the following components:
• Process Description: A description of the use, including the role of the chemical in the use;
process vessels, equipment, and tools used during the use; and descriptions of the worker
activities, including an assessment for potential points of worker exposure.
• Number of Sites: An estimate of the number of sites that use the chemical for the given use.
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• Number of Workers and Occupational Non-Users: An estimate of the number of workers and
occupational non-users potentially exposed to the chemical for the given use.
• PBPK Input Parameter Determination: A development of a set of central tendency and a set
of high-end PBPK input parameters for each occupational exposure scenario within a use,
accounting for both inhalation and dermal exposure.
1.4 Approach and Methodology for Occupational Exposures
EPA reviewed data such as general facility data (e.g., process descriptions, NMP concentration data),
inhalation monitoring data (i.e., personal exposure monitoring data and area monitoring data), and
environmental release data, found in published literature. Literature sources were evaluated using the
evaluation strategies laid out in Appendix D of the Application of Systematic Review in TSCA Risk
Evaluations (U.S. EPA. 2018a). Results of the evaluations are in the supplemental files titled "Risk
Evaluation for N-Methylpyrrolidone (NMP), Systematic Review Supplemental File: Data Quality
Evaluation for Occupational Exposure and Release Data. Docket EPA-HQ-OPPT-2019-0236" and "Risk
Evaluation for N-Methylpyrrolidone (2-Pyrrolidinone, 1-Methyl-) Systematic Review Supplemental
File: Data Quality Evaluation of Environmental Releases and Occupational Exposure Common Sources.
Docket EP A-HQ-OPPT-2019-023 6."
Each data source received an overall confidence of high, medium, low or unacceptable. For the risk
evaluation, EPA used the data of the highest quality. Data of lower rated quality may be used to
supplement analyses. Data that were found to be unacceptable were not used for risk assessment
purposes. Overall confidence ratings for the data used in this document (i.e., high, medium, low or
unacceptable) are included in Section 2 and the tables in Appendix A.
1.4.1 Process Description
EPA performed a literature search to find descriptions of processes involved in each use to identify
worker activities that could potentially result in occupational exposures. Where process descriptions
were unclear or not available, EPA referenced relevant Emission Scenario Documents (ESDs) or
Generic Scenarios (GSs). Process descriptions for each use can be found in Section 2.
1.4.2 Number of Sites, Workers, and ONUs
Where available, EPA used CDR data to provide a basis to estimate the numbers of sites, workers, and
occupational non-users (ONUs). EPA supplemented the available CDR data with U.S. economic data
using the following method:
1. Identify the North American Industry Classification System (NAICS) codes for the industry
sectors associated with these uses.
2. Estimate total employment by industry/occupation combination using the Bureau of Labor
Statistics" (BLS) Occupational Employment Statistics (OES) data ( . 2016).
3. Refine the OES estimates where they are not sufficiently granular by using the U.S. Census'
Statistics of US Businesses (SUSB) (citation) data on total employment by 6-digit NAICS.
4. Use market penetration data to estimate the percentage of employees likely to be using NMP
instead of other chemicals.
5. Combine the data generated in Steps 1 through 4 to produce an estimate of the number of
employees using NMP in each industry/occupation combination, and sum these to arrive at a
total estimate of the number of employees with exposure.
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Market penetration data for NMP are not readily available at this time; therefore, site, worker, and ONU
estimates do not take this into account and likely overestimate the number of sites, workers, and ONUs
potentially exposed to NMP. Where end-use sector is not clear, relevant GSs and ESDs are used to
estimate the number of sites and workers, such as for metal finishing.
1.4.3 PBPK Input Parameter Determination
For each occupational exposure scenario, PBPK modeling requires a set of input parameters related to
both dermal and inhalation exposures. The occupational exposure parameters and information needed
for the PBPK modeling are the following:
NMP weight fraction in the liquid product;
Total skin surface area in contact with the liquid product;
Glove protection factor (if applicable);
Duration of dermal contact with the liquid product;
Air concentration for inhalation and vapor-through-skin exposure; and
Body weight of the exposed worker.
EPA assumed that the skin of the hands was exposed dermally to NMP at the specified liquid weight
fraction and skin surface area and that there was simultaneous exposure by inhalation and vapor-
through-skin absorption for unobstructed skin areas. As described below, air concentrations were
adjusted to duration of contact of liquid on the skin, which is assumed to be removed by cleaning at the
end of the work period. Acute scenarios assumed 1 day of exposure and chronic scenarios assumed 5
days of exposure per week.
EPA used literature sources for estimating many of these occupational exposure parameters. EPA used
modeling or generic assumptions when data were not available. For most PBPK input parameters, EPA
did not find enough data to determine statistical distributions of the actual exposure parameters and
concentrations. Within the distributions, central tendencies describe 50th percentile or the substitute that
most closely represents the 50th percentile. The high-end of a distribution describes the range of the
distribution above 90th percentile (U.S. EPA. 1992). Ideally, EPA would use the 50th and 95th
percentiles for each parameter. Where these statistics were unknown, the mean or mid-range (mean is
preferable to mid-range) served as substitutes for 50th percentile and the high-end of ranges served as a
substitute for 95th percentile. However, these substitutes were highly uncertain and not ideal substitutes
for the percentiles. EPA could not determine whether these substitutes were suitable to represent
statistical distributions of real-world scenarios.
For each occupational exposure scenario, EPA developed two sets of PBPK input parameters, one
representative of central tendency conditions and one representative of high-end conditions. To generate
each central tendency scenario result, EPA used a group of all central tendency input parameter values
relevant to the scenario. To generate each high-end scenario result, EPA used a group of mostly high-
end input parameter values relevant to the scenario except body weight, which is a median value. Using
mostly high-end input values is a plausible approach to estimate a high-end PBPK result for the periods
of acute and chronic exposures of 1 to 5 days.
A central tendency is assumed to be representative of occupational exposures in the center of the
distribution for a given use. For risk evaluation, EPA may use the 50th percentile (median), mean
(arithmetic or geometric), mode, or midpoint values of a distribution as representative of the central
tendency scenario. EPA's preference is to provide the 50th percentile of the distribution. However, if the
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full distribution is not known, EPA may assume that the mean, mode, or midpoint of the distribution
represents the central tendency depending on the statistics available for the distribution.
A high-end is assumed to be representative of occupational exposures that occur at probabilities above
the 90th percentile but below the exposure of the individual with the highest exposure (U.S. EPA. 1992).
For risk evaluation, EPA provided high-end results at the 95th percentile, where available. If the 95th
percentile is not available, EPA may use a different percentile greater than or equal to the 90th percentile
but less than or equal to the 99.9th percentile, depending on the statistics available for the distribution. If
the full distribution is not known and the preferred statistics are not available, EPA may estimate a
maximum or bounding estimate in lieu of the high-end.
1.4.3.1 General Approach
This section discusses EPA's general approach for data selection. EPA follows the following hierarchy
in selecting data and approaches for estimating air concentrations:
1. Monitoring data:
a. Personal and directly applicable
b. Area and directly applicable
c. Personal and potentially applicable or similar
d. Area and potentially applicable or similar
2. Modeling approaches:
a. Surrogate monitoring data
b. Fundamental modeling approaches
c. Statistical regression modeling approaches
3. Occupational exposure limits:
a. Company-specific occupational exposure limits (OELs) (for site-specific exposure assessments,
e.g., there is only one manufacturer who provides to EPA their internal OEL but does not
provide monitoring data)
b. Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL)
c. Voluntary limits (American Conference of Governmental Industrial Hygienists [ACGIH]
Threshold Limit Value [TLV], National Institute for Occupational Safety and Health [NIOSH]
Recommended Exposure Limits [RELs], Occupational Alliance for Risk Science (OARS)
workplace environmental exposure level [WEEL] [formerly by AIHA])
Within each level of the hierarchy, EPA used the data with the highest overall confidence rating from
EPA's systematic review process. Note that EPA did not rate EPA models used to estimate air
concentrations; where these models are used, the overall confidence rating is listed as "not applicable".
EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically
review models that were developed by EPA.
Exposures are calculated from the datasets provided in the sources depending on the size of the dataset.
For datasets with six or more data points, central tendency and high-end exposures were estimated using
the 50th percentile and 95th percentile. For datasets with three to five data points, central tendency
exposure was calculated using the 50th percentile and the maximum was presented as the high-end
exposure estimate. For datasets with two data points, the midpoint was presented as a midpoint value
and the higher of the two values was presented as a higher value. Finally, data sets with only one data
point presented the value as a what-if exposure. For datasets including exposure data that were reported
as below the limit of detection (LOD), EPA estimated the exposure concentrations for these data,
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following EPA's Guidelines for Statistical Analysis of Occupational Exposure Data (EPA. 1994). which
recommends using the -j=- if the geometric standard deviation of the data is less than 3.0 and —if the
geometric standard deviation is 3.0 or greater. Specific details related to each occupational exposure
scenario can be found in Section 2.
Air concentrations may be a point estimate (i.e., a single descriptor or statistic, such as central tendency
or high-end) or a full distribution. EPA will consider three general approaches for estimating air
concentrations:
• Deterministic calculations: EPA will use combinations of point estimates of each model
parameter to estimate a central tendency and high-end for air concentration. EPA will document
the method and rationale for selecting parametric combinations to be representative of central
tendency and high-end.
• Probabilistic (stochastic) calculations: EPA will pursue Monte Carlo simulations using the full
distribution of each parameter to calculate a full distribution of the air concentration results and
selecting the 50th and 95th percentiles of this resulting distribution as the central tendency and
high-end, respectively.
• Combination of deterministic and probabilistic calculations: EPA may have full distributions for
some parameters but point estimates of the remaining parameters. For example, EPA may pursue
Monte Carlo modeling to estimate exposure concentrations, but only have point estimates of
working years of exposure, exposure duration and frequency, and lifetime years. In this case,
EPA will document the approach and rationale for combining point estimates with distribution
results for estimating central tendency and high-end results.
EPA follows the following hierarchy in selecting data and approaches for estimating other dermal input
parameters:
1. Monitoring data (in general, for weight fractions of NMP, glove usage information, and exposure
durations).
2. Industry data:
a. Data provided directly by industry (i.e., public comments, reports written by the company where
the data originates from, safety datasheets [SDSs])
b. Industry data from an indirect source (i.e., government documents, other risk assessment reports,
online vendors [for weight fractions of NMP])
3. Values from the 2011 edition of EPA's Exposure Factors Handbook (U.S. EPA. ).
4. Assumptions
1.4.3.2 Approach for this Risk Evaluation
For most exposure parameters, EPA did not find enough data to determine statistical distributions of the
actual exposure parameters. As described in Section 1.4.3, ideally, EPA would like to know 50th and
95th percentiles for each parameter. However, where these percentiles were unavailable, EPA used
substitutes such as mid-ranges or high-ends. These substitutes were highly uncertain and not ideal
substitutes for the percentiles. EPA could not determine whether these values were suitable to represent
statistical distributions of real-world scenarios.
Parameters were selected for the most sensitive populations: pregnant women and females of
reproductive age who may become pregnant.
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1.4.3.2.1 Weight Fraction of NMP
EPA determined the weight fraction of NMP in various products through information provided in the
available literature, previous risk assessments and the 2017 NMP Market Profile (Abt 2017). This
Market Profile was prepared in part by searching Safety Data Sheets (SDSs) of products that contain
NMP and compiling the associated name, use, vendor and NMP concentration associated with each of
these products. Where a data point was provided as range of NMP concentrations for a certain product
(e.g., paints and coatings), EPA utilized the mid-range (middle) and high-end (maximum) weight
fractions to estimate potential exposures. Where multiple data points for a given type of product (e.g.,
paints and coatings) were available, EPA estimated exposures using the central tendency (50th
percentile) and high-end (95th percentile) NMP concentrations.
1.4.3.2.2 Skin Surface Area
For both consumer and occupational dermal exposure assessments, EPA used skin surface area values
both for the hands of females and the hands of males, obtained from the 2011 edition of EPA's Exposure
Factors Handbook (Table 7-13) (U.S. EPA. 2011). These values overestimate exposures for younger
members of the workforce whose hand surface areas would be smaller. One exception is for the OES
that includes Writing, 1 cm2 was assumed based on a literature estimate for writing inks (Australian
Government Department of Health. 2016). For the remainder of the occupational dermal exposure
assessment, EPA used the following values:
• high-end value, which represents two full hands exposed to a liquid: 890 cm2 (female), 1,070
cm2 (males)
• central tendency value, which is half of two full hands (equivalent to one full hand) exposed to a
liquid and represents only the palm-side of both hands exposed to a liquid: 445 cm2 (females),
535 (males)
ONUs are not expected to have direct contact with NMP-based liquid products unless an incident (e.g.,
spill) were to occur. However, PBPK modeling of ONU (no liquid contact) used a skin surface area
value of 0.1 cm2 (about 0.1% of values used for occupational users) for liquid exposure to prevent a
division by zero error in model equations.
For dermal exposure to vapor for both occupational users and ONUs, the PBPK modeled up to 25% of
the total skin surface area, corresponding to the face, neck, arms and hands, as exposed to and capable of
absorbing vapors, minus any area covered by personal protection equipment (PPE). This area, which is
programmed into the PBPK model, is not a variable input value.
1.4.3.2.3 Glove Usage
EPA also made assumptions about glove use and associated protection factors (PFs). Where workers
wear gloves, workers are exposed to NMP-based product that penetrates the gloves, including potential
seepage through the cuff from improper donning of the gloves, permeation of NMP through the glove
material, and the gloves may occlude the evaporation of NMP from the skin. Where workers do not
wear gloves, workers are exposed through direct contact with NMP.
Overall, EPA understands that workers may potentially wear gloves but does not know the likelihood
that workers wear gloves of the proper material and have training on the proper usage of gloves. Some
sources indicate that workers wear chemical-resistant gloves (Meier et at.. 2013: OECD. 2009:
NICNAS. 2001). while others indicate that workers likely wear gloves that provide a lower protection
factor (RIVM. 2013). No information on employee training was found. Data on the prevalence of glove
use is not available for most uses of NMP. One anecdotal survey of glove usage among workers
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performing graffiti removal indicates that most workers wear gloves, although the glove materials varied
and were sometimes not protective ( 1015b). Prior to the initiation of this risk evaluation, EPA
had gathered information in support of understanding glove use for handling pure NMP and for paint
and coatings removal using NMP formulations. This information may be generally useful for a broader
range of uses of NMP and is presented for illustrative purposes in Appendix E of the Risk Evaluation.
SDSs found by EPA recommend glove use. Initial literature review suggests that there is unlikely to be
sufficient data to justify a specific probability distribution for effective glove use for a chemical or
industry. Instead, the impact of effective glove use is explored by considering different protection
factors, which are further discussed below and compiled in Table 1-2.
Gloves only offer barrier protection until the chemical breaks through the glove material. Using a
conceptual model, Cherrie (2004) proposed a glove workplace protection factor (PF) - the ratio of
estimated uptake through the hands without gloves to the estimated uptake though the hands while
wearing gloves: this protection factor is driven by glove usage practices and by flux, which varies with
time. The ECETOC TRA v3 model represents the protection factor of gloves as a fixed, assigned
protection factor equal to 5, 10, or 20 (Marquart et at.. 2.017). When assuming glove use, EPA assumed
protections factors using this strategy. Given the limited state of knowledge about the protection
afforded by gloves in the workplace, it is reasonable to utilize the PF values of the ECETOC TRA v3
model (Marquart et at.. 2017). rather than attempt to derive new values.
For each occupational exposure scenario, EPA used judgement to predict the likelihood of the use of
gloves based on the characteristics described in Table 1-2 below. For OESs with only industrial sites,
EPA assumes that workers are likely to wear protective gloves and have basic training on the proper
usage of these gloves, corresponding to a protection factor of 10 for both the central tendency and high-
end exposure scenarios. In high-end scenarios that include both commercial and industrial sites, EPA
assumes that either no gloves are used or, if gloves are used, that glove material may not be protective,
each of which corresponds to a protection factor of 1. For these same scenarios, EPA assesses a central
tendency scenario assuming the use of gloves with minimal to no employee training, corresponding to a
protection factor of 5. As indicated in Table 1-2, use of protection factors above 1 is valid only for glove
materials that have been tested for permeation against the NMP-containing liquids associated with the
condition of use. EPA has not found information that would indicate specific activity training (e.g.,
procedure for glove removal and disposal) for tasks where dermal exposure can be expected to occur in
industrial OESs, so the PF of 20 is not assumed for any central tendency or high-end estimates. EPA
also considered potential dermal exposure in cases where exposure is occluded. If occlusion were to
occur, contact duration would be extended and glove protection factors could be reduced, although such
extensions and reductions could not be quantified for this evaluation due to lack of data.
Table 1-2. Glove Protection Factors for Different Dermal Protection Strategies from ECETOC
TRA v3
Dcrniiil Prolcclion ( li;u ;ic(c'i is(ics
Selling
Prulcclion l ;ic(or.
PI-
a. No gloves used, or any glove / gauntlet without permeation data and without
employee training
Industrial and
Commercial Uses
1
b. Gloves with available permeation data indicating that the material of
construction offers good protection for the substance
5
c. Chemically resistant gloves (i.e., as b above) with "basic" employee training
10
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Dcrniiil Protect ion ( liiii'iiclorislics
Selling
Prulcclion l;ic(or.
PI
d. Chemically resistant gloves in combination with specific activity training
(e.g., procedure for glove removal and disposal) for tasks where dermal
exposure can be expected to occur
Industrial Uses
Only
20
1.4.3.2.4 Duration of Dermal Contact
Where available, EPA utilized exposure durations from the available task-based inhalation monitoring
data. No dermal duration data was found. In lieu of dermal duration data or task-based durations from
inhalation monitoring data, EPA assumed a minimum duration of 1 hour/day, which is a reasonable
assumption considering the initial contact time with the formulation containing NMP plus the time after
direct contact when the thin film evaporates from and absorbs into the skin. EPA assumed a high-end
value of 8 hours/day (i.e., a full shift). As a central tendency estimate, EPA assumed a mid-range value
of 4 hours/day (the calculated mid-point of 4.5 was rounded to 4 hours/day). The low-end and high-end
values are consistent with EPA's documented standard model assumptions for occupational dermal
exposure modeling (U.S. EPA. 1991).
1.4.3.2.5 Air Concentration for Inhalation and Vapor-through-Skin Exposure
EPA reviewed workplace inhalation monitoring data collected by government agencies such as OSHA
and NIOSH, and monitoring data found in published literature (i.e., personal exposure monitoring data
and area monitoring data). Data were evaluated using the evaluation strategies laid out in the Application
of Systematic Review in TSCA Risk Evaluations ( ). Where available, EPA used air
concentration data and estimates found in government or published literature sources to serve as inputs
to the PBPK modeling for occupational exposures to NMP. There is not a known correlation between
weight fraction of NMP in the material being handled / used and the concentration of NMP in air. Where
air concentration data were not available, data for the use of NMP in similar but different work activities
(surrogate approach) or modeling estimates were used. Details on which approaches and models EPA
used are included in Section 2 for the applicable OESs and discussion of the uncertainties associated
with these approaches and models is included in Section 3.2.
Inhalation data sources did not usually indicate whether NMP exposure concentrations were for
occupational users or nearby occupational non-users. In these cases, EPA assumed that inhalation
exposure data were applicable for a combination of users and nearby occupational non-users (ONUs);
EPA used the same inhalation exposure estimates for both occupational users and ONUs. While some
ONUs may have lower inhalation exposures than users, especially when they are further away from the
source of exposure, EPA assumed that ONUs that may be near workers handling NMP.
For PBPK modeling, the duration of inhalation exposure must equal the duration of dermal exposure.
Therefore, where EPA did not have exposure durations from task-based monitoring data, EPA adjusted
air concentrations by multiplying by a ratio of duration of the air concentration averaging time to
duration of dermal exposure to liquid, which is discussed above.
Few literature sources indicate the use of respirators for reducing worker exposures to NMP by
inhalation. Therefore, EPA central tendency and high-end scenarios do not incorporate protection factors
for respirator use. Regarding respirator use, only one of the NMP studies containing worker inhalation
data specified the type of respirator used by the workers in the study. This respirator, a half mask air-
purifying respirator with organic vapor cartridges (Kiefer. 1994). is classified as having an assigned
protection factor (APF) of 10. Therefore, EPA conducted additional modeling representing scenarios
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below central tendency for the use of respirators providing an APF of 10. This modeling reduces
inhalation concentrations by a factor of 10 as intended when this type of respirator is used in accordance
with OSHA's Respiratory Protection standard (29 CFR 1910.134). While respirators with other APFs
may be used, EPA only included this APF in additional modeling. The results of this additional
modeling are shown in Section 4 of the Risk Evaluation.
1.4.3.2.6 Body Weight
Both the consumer and occupational dermal exposure assessments used the 50th percentile body weight
value for pregnant women in their first trimester, which is 74 kg, and for males, which is 88 kg, for both
the central tendency and high-end exposure scenarios. EPA obtained this value from the 2011 edition of
EPA's Exposure Factors Handbook (Table 8-29) (U.S. EPA. 2011Y
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2 Engineering Assessment
The following sections will contain process descriptions and the specific details (worker activities,
analysis for determining number of workers, exposure assessment approach and results, release sources,
media of release, and release assessment approach and results) from the assessment for each
release/exposure scenario.
2.1 Manufacturing
2.1.1_ Process Description
NMP can be manufactured using multiple reaction pathways and relevant different processing steps.
One method involves reaction of butyrolactone with an excess of pure or aqueous methylamine in a
high-pressure tube ( JCBI. 2017; NIK 2017; Harreus et al.. 201 i; TURK 1996). This reaction is shown
in Figure 2-1 and is taken from (Anderson and Liu. 2000). This exothermic reaction takes place under
adiabatic conditions and produces a reaction product containing NMP that is subsequently distilled to
purify the produced NMP. This method of manufacturing results in a 97% yield of NMP ( arreus et al..
2011).
o
+ CH3NH2 HO(CH2)3CNHCH3 —-1 I + h2o
0^0 N^O
CH3
Figure 2-1. NMP Manufacturing Under Adiabatic Conditions
Another similar process for manufacturing NMP involves reacting gamma-butyrolactone (GBL) and
monomethylamine (MMA), as shown in Figure 2-2 (Johnson Matthev Process Technologies. 2017).
This reaction is non-catalyzed and takes place in two stages. The first stage produces a long-chain amide
that is cyclized, then dehydrated to form NMP during the second stage of the reaction. The reaction
product that contains NMP is then distilled to purify the NMP.
6
\ C\
+ N—CH, » + H20
1
ch3
gamma • butyrolactone MMA n-methyi-2-pyrrolidone water
(GBL) (NMP)
Figure 2-2. NMP Manufacturing Using Gamma-Butyrolactone (GBL) and Monomethylamine
(MMA)
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Other methods of NMP manufacturing include high pressure synthesis from acetylene and formaldehyde
(NIH. 2017; TLIR.I, 1996) carbonylation of allylamine (Barrens et at... ), and hydrogenation of
maleic anhydride or succinic acid and methylamine (Mitsubishi Chemical. 2017; NIH. 2017).
Methods of manufacturing may depend on the specifications for the end product. For example, higher
purities of NMP are generally required for electronic applications ( ).
2.1.2 Exposure Assessment
2.1.2.1 Worker Activities
Workers are potentially exposed to NMP during the manufacture of NMP from sampling, equipment
maintenance, cleaning activities, and loading NMP into containers (RIVM. 2013). These activities are
all potential sources of worker exposure through dermal contact, vapor-through-skin, and inhalation of
NMP vapors.
The 2013 Netherlands' National Institute for Public Health and the Environment (RIVM) Proposal for
Restriction - NMP report indicates that the production, storage, and bulk transfers of NMP are all
conducted within closed systems ( . 2013). In addition, this report indicates that bulk transfers of
NMP may occur with either open or closed transfer lines. Filling of smaller containers is expected to
occur at dedicated filling points equipped with ventilation.
The RIVM Annex XV Proposal for a Restriction - NMP report indicates that sites that manufacture NMP
are expected to implement local exhaust ventilation (LEV) and wear proper chemical-specific personal
protective equipment, including appropriate gloves ( . 2013). Specifically, workers wear gloves
with an assigned protection factor (APF) of 5 (80 percent exposure reduction) (RIVM. 2013). EPA did
not find information that indicates the extent that engineering controls and worker PPE are used at
facilities that manufacture NMP in the United States.
ONUs include employees that work at the sites where NMP is manufactured, but they do not directly
handle the chemical and are therefore expected to have lower inhalation exposures and vapor-through-
skin uptake and are not expected to have dermal exposures by contact with liquids. ONUs for this
scenario include supervisors, managers, and other employees that may be in the production areas but do
not perform tasks that result in the same level of exposures as those workers that engage in tasks related
to the manufacturing of NMP.
2.1.2.2 Number of Potentially Exposed Workers
EPA estimated the number of workers and occupational non-users potentially exposed to NMP at
manufacturing sites using 2016 CDR data (where available), 2016 TRI data (where available), Bureau of
Labor Statistics" OES data ( L 2016) and the U.S. Census" SUSB (U.S. Census Bureau. 2015).
The method for estimating number of workers from the Bureau of Labor Statistics' OES data and U.S.
Census' SUSB data is detailed in Appendix B.l. These estimates were derived using industry- and
occupation-specific employment data from the BLS and U.S. Census.
The 2016 CDR non-CBI results identify a total of 33 sites that manufacture, import, or both manufacture
and import NMP (U.S. EPA. 2016a). Of these 33 sites, five sites report domestic manufacture of NMP
and an additional six sites claim the domestic manufacture/import activity field as either CBI or
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withheld.1 To try to determine whether the remaining six CDR sites were manufacturers or importers,
EPA mapped the sites to 2016 TRI data using the facility names and addresses but did not find these
sites in 2016 TRI (reporting releases of NMP) (U.S. EPA 2016b). EPA assumed that these six sites for
which the activity could not be determined through CDR or TRI may import or manufacture NMP.
Therefore, there may be up to 11 sites that domestically manufacture NMP.
Of these 11 sites, one site reports that there are at least 50 but fewer than 100 workers potentially
exposed to NMP, three sites report that there are at least 100 but fewer than 500 workers potentially
exposed to NMP, and one site reports that there are at least 500 but fewer than 1,000 workers potentially
exposed to NMP. The remaining sites claim number of worker estimates as CBI. EPA compiled these
worker estimates in Table 2-1.
In addition to worker estimates from the 2016 CDR results, EPA compiled the number of workers and
ONUs for NAICS code 325199 in Table 2-1 using data obtained from the BLS. To determine the
number of workers potentially exposed, EPA used one less than the range of number of workers
reported in the 2016 CDR for the manufacturing sites that reported worker information as non-CBI. For
the CDR submissions that claimed number of workers as CBI and for the additional sites identified per
2016 TRI data, EPA used the number of workers estimate from the BLS data for NAICS code 325199.
To determine the number of ONUs potentially exposed, EPA used the ratio of ONUs to workers from
BLS data multiplied by the total number of workers estimated with BLS and CDR data. Note that these
estimates may be overestimates of the actual number of employees potentially exposed to NMP.
Table 2-1. US Number of Establishments and Employees for Manufacturing
Source
Number of
Establishments
Number of
Workers per Site
Number
of ONUs
per Site
(U.S. BLS. 2016) data for NAICS 325199. All Other
Basic Organic Chemical Manufacturing
Not included in
this estimate
39a
18a
2016 CDR results indicate up to 11 sites manufacture
NMP
1
at least 50 but
fewer than 100 b
Unknown
- used
BLS
estimate
3
at least 100 but
fewer than 500 b
1
at least 500 but
fewer than 1,000 b
6
Unknown - used
BLS estimate
Total establishments and number of potentially exposed
workers and ONUs =c
11
2,800
200d
a - Rounded to the nearest whole number.
b - EPA uses one less than the upper end of this range for worker calculations (i.e., for "at least 50 but fewer than 100
workers, EPA assumes 99 workers).
c - Totals may not add exactly due to rounding to two significant figures.
d - EPA used the number of ONUs per site from BLS data to calculate the total number of ONUs using CDR estimate for
number of sites.
1 Manufacturers (including importers) are required to report under CDR if they meet certain production volume thresholds,
generally 25,000 lb or more of a chemical substance at any single site. Reporting is triggered if the annual reporting
threshold is met during any of the calendar years since the last principal reporting year. In general, the reporting threshold
remains 25,000 lb per site. However, a reduced reporting threshold (2,500 lb) now applies to chemical substances subject
to certain TSCA actions, https://www.epa.gov/chemical-data-reporting/how-report-under-chemical-data-reporting
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2.1.2.3 Occupational Exposure Assessment Methodology
In the occupational exposure assessment for this scenario, EPA assesses potential exposure from the
loading of various containers (i.e., drums, tank trucks, rail cars) with pure NMP. While EPA does expect
that workers may perform additional activities during this scenario, such as sampling or maintenance
work, EPA expects that loading activities present the largest range of potential exposures.
2.1.2.3.1 Inhalation
Due to limited relevance and quality of monitoring data and modeling estimates for manufacturing of
NMP found in the published literature, EPA used modeling estimates with the highest data quality for
this use, as further described below.
Limited monitoring data for the manufacture of NMP are available based on the information searched at
the time of preparation of this report. The one source with monitoring data ( 10), is for the storing
and conveying of NMP; however, no additional details on these data were provided so EPA did not use
these data. Modeled inhalation exposure concentrations during the manufacturing of NMP were
included in the RIVM Annex XV Proposal for a Restriction - NMP report, specifically in the context of
closed- and open-system transfers of NMP. The proposal report indicated closed system transfers are
likely for manufacturing of NMP. EPA modeled potential worker inhalation exposures during the
loading of bulk storage containers (i.e., tank trucks and rail cars) and drums using a common loading
model developed by EPA and compared them to the modeled exposures in the RIVM Annex XV
Proposal for a Restriction - NMP report. EPA's modeled exposure concentrations for loading NMP into
bulk containers are similar in value and the same order of magnitude as those modeled by RIVM for
closed-system NMP transfers. EPA's modeled exposure concentrations for loading NMP into drums are
the same magnitude but higher in value than those modeled by RIVM for open-system NMP transfers.
EPA's modeled exposure concentrations represent a larger range of potential inhalation exposure
concentrations than those presented by RIVM. EPA assessed the range of occupational inhalation
exposures modeled by EPA for this scenario. The discussed inhalation monitoring data as well as the
RIVM and EPA's modeled exposure concentrations are summarized and further explained in Appendix
A. 1.
The inhalation exposure concentrations modeled by EPA for loading of 100% NMP are summarized into
the input parameters used for the PBPK modeling in Table 2-2. The container loading models used by
EPA calculate short-term exposure concentrations, with the exposure duration equal to the duration of
the loading event (for bulk containers, typical case is 0.5 hours for loading tank trucks and worst-case is
1 hour for loading rail cars; for drums, 20 containers are loaded per hour and the duration was
determined based on the throughput of NMP at a site [refer to Appendix A. 1 for further explanation])
and number of loading events per day. EPA calculated the 8-hour TWA exposures as the weighted
average exposure during an entire 8-hour shift, assuming zero exposure during the remainder of the
shift.
The Tank Truck and Railcar Loading and Unloading Release and Inhalation Exposure Model involves
deterministic modeling and the Drum Loading and Unloading Release and Inhalation Exposure Model
involves probabilistic modeling. See Appendix B.2 and B.3 for additional details on the bulk container
loading modeling and the drum loading modeling, respectively.
Table 2-2. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Manufacturing
Work
l*:i rsi meter
1'iill-Shift NMP
l)ii riilion-liiised
Source
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Activity
Characterization
Air
Concentration
NMP Air
Concentration
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Loading
NMP into
bulk
containers
Central tendency
(50th percentile)
0.047
0.76 (duration =
0.5 hour)
Tank Truck and
Railcar Loading and
Unloading Release
and Inhalation
Exposure Model (U.S.
EPA. 2013a)
Not
applicable3
High-end (95th
percentile)
0.19
1.52 (duration = 1
hour)
Loading
NMP into
drums
Central tendency
(50th percentile)
0.427
1.65 (duration =
2.06 hour)
EPAOAOPS AP-42
Loading Model and
EPA/OPPTMass
Balance Model (U.S.
EPA. 2013a)
High-end (95th
percentile)
1.51
5.85 (duration =
2.06 hour)
a - EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically review models
that were developed by EPA.
2.1.2.3.2 Dermal
Table 2-3 summarizes the parameters used to assess dermal exposure during the manufacturing of NMP.
EPA assesses dermal exposure to NMP at the specified concentration weight fraction, skin surface area,
and exposure duration, based on the methodology described below. During the manufacturing of NMP,
workers are potentially exposed during sampling, maintenance, and loading (packaging) activities. For
this scenario, EPA assessed dermal exposures during the loading of pure NMP into bulk containers and
into drums. See below for additional information.
NMP Weight Fraction
For this scenario, EPA gathered NMP concentration data from the non-CBI 2016 CDR results and
literature. The 2016 CDR results include four submissions with non-CBI concentration data that indicate
NMP is manufactured at least 90 weight percent NMP (U.S. EPA 2016a). Because CDR reporting is in
ranges, the category for at least 90 weight percent includes those products that are between 90 and 100
weight percent. The RIVM Annex XV Proposal for a Restriction - NMP report indicates that
manufactured NMP is sold at a purity of at least 80 weight percent and up to 100 weight percent (RIVM.
2013). Other sources indicate manufactured NMP is sold at a purity of 99.8 (TURL 1996) and up to 100
weight percent NMP per 2012 CDR (U.S. EPA 2012). All underlying data from these sources have an
overall confidence rating of high. Based on this information, EPA assesses dermal exposures at 100
weight percent NMP, as a likely exposure scenario.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. Because NMP manufacturing occurs at industrial sites, EPA expects that the use of gloves is
likely (RIVM. 2013). Workers are likely to wear protective gloves and have basic training on the proper
usage of these gloves, corresponding to a protection factor of 10 from Table 1-2 of Section 1.4.3.2.3.
Thus, EPA assesses a protection factor 10 for both the central tendency and high-end scenarios for this
scenario. EPA did not find data on the use of gloves for this occupational exposure scenario and the
glove protection factor assumptions are based on professional judgment. The assumed glove protection
factor values are highly uncertain.
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Exposure Duration
For the loading of bulk containers, EPA assesses an exposure duration of half an hour and one hour,
based on the typical and worst-case scenarios assessed for inhalation exposures during the loading of a
tank truck and rail car, respectively. For loading of drums, EPA modeled the exposure duration to be
2.06 hours, based on annual NMP throughput at each site (determined from the production volume and
number of sites from 2016 CDR), 250 days of operation per year, and a loading rate of 20 drums per
hour. Refer to Appendix A. 1 for additional information on this exposure duration calculation.
Table 2-3. Summary of Parameters for Worker Dermal Exposure to Liquids During
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area Exposed
a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Loading NMP
into bulk
containers
Central Tendency
10
1
445 (f)
535 (m)
0.5
74 (f)
High-end
10
1
890 (f)
1,070 (m)
1
88 (m)
Loading NMP
Central Tendency
10
1
445 (f)
535 (m)
2.06
74 (f)
into drums
High-end
10
1
890 (f)
1,070 (m)
2.06
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.1.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-4.
The numeric parameters corresponding to the characterizations presented in Table 2-4 are summarized
in Table 2-5. These are the inputs used in the PBPK model.
Table 2-4. Characterization of PBPK Model Input Parameters for Manufacturing of NMP
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Ch ar acteriz ation
Central
Tendency
Loading of
bulk
containers
Central tendency
(50th percentile)
Duration
calculated
by model
1-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
High-end
Loading of
drums
High-end (95th
percentile)
Duration
calculated
by model
2-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
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Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
0.76
0.5
445 (f)
535 (m)
10
1
74 (f)
88 (m)
High-end
5.85
2.06
890 (f)
1,070 (m)
10
1
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.1.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.2 Repackaging
2.2.1 Process Description
In general, commodity chemicals are imported into the United States in bulk via water, air, land, and
intermodal shipments (Tomer and Kane. 2015). These shipments take the form of oceangoing chemical
tankers, railcars, tank trucks, and intermodal tank containers. Chemicals shipped in bulk containers may
be repackaged into smaller containers for resale, such as drums or bottles. Domestically manufactured
commodity chemicals may be shipped within the United States in liquid cargo barges, railcars, tank
trucks, tank containers, intermediate bulk containers (IBCs)/totes, and drums. Both imported and
domestically manufactured commodity chemicals may be repackaged by wholesalers for resale; for
example, repackaging bulk packaging into drums or bottles.
The exact shipping and packaging methods specific to NMP are not known. For this risk evaluation,
EPA assesses the repackaging of NMP from bulk packaging to drums at wholesale repackaging sites
(see Figure 2-3).
Unloaded from
larger containers
and loaded into
smaller containers
Smaller containers
shipped to
customers for use
NMP received in rail
cars, tanks, or totes
Figure 2-3. General Process Flow Diagram for Repackaging
This scenario includes the repackaging of both pure NMP and formulations containing NMP.
2.2.2 Exposure Assessment
2.2.2.1 Worker Activities
During repackaging, workers are potentially directly exposed while connecting and disconnecting hoses
and transfer lines to containers and packaging to be unloaded (e.g., railcars, tank trucks, totes),
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intermediate storage vessels (e.g., storage tanks, pressure vessels), and final packaging containers (e.g.,
drums, bottles). These activities are potential sources of worker exposure through dermal contact, vapor-
through-skin, and inhalation of NMP vapors. Workers are also potentially directly exposed through the
same pathways to incidental leaks or spills. Workers near loading racks and container filling stations are
potentially exposed to fugitive emissions from equipment leaks and displaced vapor as containers are
filled.
The RIVM Annex XV Proposal for a Restriction - NMP report recommends that workers conducting
repackaging activities wear gloves with an assigned protection factor (APF) of 5 (80 percent exposure
reduction) (K1V ). This report also indicates that LEV may be employed but is not customary.
EPA did not find information that indicates the extent that engineering controls and worker PPE are used
at facilities that repackage NMP in the United States.
ONUs include employees that work at the site where NMP is repackaged, but they do not directly handle
the chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin
uptake and are not expected to have dermal exposures by contact with liquids. ONUs for repackaging
include supervisors, managers, and tradesmen that may be in the repackaging area but do not perform
tasks that result in the same level of exposures as repackaging workers.
2.2.2.2 Number of Potentially Exposed Workers
EPA estimated the number of workers and occupational non-users potentially exposed to NMP at
repackaging sites using 2016 CDR data (where available), 2016 TRI data (where available), Bureau of
Labor Statistics' OES data ( .. 2016) and the U.S. Census' SUSB (U.S. Census Bureau. 2.015).
The method for estimating number of workers from the Bureau of Labor Statistics' OES data and U.S.
Census' SUSB data is detailed in Appendix B.l. These estimates were derived using industry- and
occupation-specific employment data from the BLS and U.S. Census.
The 2016 CDR non-CBI results identify a total of 33 sites that manufacture, import, or both manufacture
and import NMP (U.S. EPA. 2016a). Of these 33 sites, there are at least 22 and up to 29 sites that
manufacture NMP, with the exact number unknown due to CBI claims.2 EPA assumes that the sites
claiming CBI may either import or domestically manufacture NMP. Of these 29 sites, eight submissions
report that NMP is imported and never at the site. EPA assumes that these eight sites do not conduct
repackaging activities. Of the remaining 21 sites, EPA mapped these sites to 2016 TRI data and found
that one of these sites does not repackage NMP, one site does repackage NMP, and the remaining sites
were not identified in TRI (EPA assumes these sites repackage NMP). Thus, EPA assumes 20 sites
import and repackage NMP, per 2016 CDR results. Of the 21 import and repackaging sites, six sites
report that there are fewer than 10 workers potentially exposed to NMP, one site reports at least 10 but
fewer than 25 workers, five sites report at least 50 but fewer than 100 workers, and one site reports that
there are at least 100 but fewer than 500 workers potentially exposed to NMP. The remaining sites claim
number of workers estimates as CBI or not known or reasonably ascertainable. EPA compiled these
worker estimates in Table 2-6.
2 Manufacturers (including importers) are required to report under CDR if they meet certain production volume thresholds,
generally 25,000 lb or more of a chemical substance at any single site. Reporting is triggered if the annual reporting
threshold is met during any of the calendar years since the last principal reporting year. In general, the reporting threshold
remains 25,000 lb per site. However, a reduced reporting threshold (2,500 lb) now applies to chemical substances subject
to certain TSCA actions, https://wyyyy.epa.gov/chemical-data-reporting/how-report-under-chemical-data-repqrting
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EPA determined additional sites that potentially repackage NMP using 2016 TRI results. Specifically,
EPA first identified the sites reporting operations under NAICS code 424690, Other Chemical and
Allied Products Merchant Wholesalers, and removed those sites that reported to and are captured in the
2016 CDR results. EPA then identified those sites that report repackaging operations occur, leaving 12
sites.
In addition to worker estimates from the 2016 CDR results, EPA compiled the number of workers and
ONUs for NAICS code 424690 in Table 2-6 using data obtained from the BLS. To determine the
number of workers potentially exposed, EPA used the one less than the range of number of workers
reported in the 2016 CDR for the sites that reported worker information as non-CBI. For the CDR
submissions that claimed number of workers as CBI and for the additional sites identified per 2016 TRI
data, EPA used the number of workers estimate from the BLS data for NAICS code 424690. To
determine the number of ONUs potentially exposed, EPA used the ratio of ONUs to workers from BLS
data multiplied by the total number of workers estimated with BLS and CDR data. Note that these
estimates may be overestimates of the actual number of employees potentially exposed to NMP.
Table 2-6. US Number of Establishments and Employees for Repackaging
Source
Number of
Establishments
Number of Workers per
Site
Number
of ONUs
per Site
(U.S. BLS. 2016) data for NAICS 424690.
Other Chemical and Allied Products
Merchant Wholesalers
Not included in this
estimate
la
la
Per 2016 CDR results, there are up to 29 sites
that import (21 sites with NMP at the site and
8 with NMP never at site). Per 2016 TRI
data, one of these sites does not repackage,
one site does repackage, and the remaining
sites were not identified in the TRI. EPA
assumes the unidentified sites repackage
NMP. Thus, 20 sites repackage NMP.
6
fewer than 10b
Unknown
- used
BLS
estimate
1
at least 10 but fewer than
25 b
5
at least 50 but fewer than
100b
1
at least 100 but fewer
than 500 b
7
Unknown - used BLS
estimate
The 2016 TRI identifies 43 sites reporting
operations under NAICS code 424690.
Excluding those sites included in the 2016
CDR and only including those reporting
repackaging operations results in 12 sites.
12
Unknown - not reported
in TRI - used BLS
estimate
Total establishments and number of
potentially exposed workers and ONUs = c
32 d
1,100
14 e
a - Rounded to the nearest whole number. Exact values are 1.3 workers and 0.45 ONUs.
b - EPA uses one less than the upper end of this range for worker calculations (i.e., for "at least 50 but fewer than 100
workers, EPA assumes 99 workers).
c - Totals may not add exactly due to rounding to two significant figures,
d - EPA assumes the sum of sites reported in 2016 CDR and 2016 TRI.
e - EPA used the number of ONUs from BLS data to calculate the total number of ONUs based on the number of sites per
CDR.
2.2.2.3 Occupational Exposure Assessment Methodology
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2.2.2.3.1 Inhalation
EPA compiled the same monitoring and modeled exposure concentration data for this scenario as for
manufacturing. These data are summarized in Appendix A.2. As described in the previous scenario,
Section 2.1.2.3.1, due to limited relevance and quality of monitoring data and modeling estimates found
in the published literature, EPA used modeling estimates with the highest data quality for this use, as
further described below.
EPA only found one source with monitoring data on the storing and conveying of NMP, which did not
include details on worker activities, sample locations, or sampling times. EPA also summarized in
Appendix A.2 the modeled inhalation exposure concentrations during the manufacturing of NMP, for
closed- and open-system transfers of NMP, that were presented in the RIVM Annex XV Proposal for a
Restriction - NMP report (RIVM. 2013).
Consistent with the approach EPA took in Section 2.1.2.3.1 for the manufacture of NMP, EPA modeled
potential worker inhalation exposures during the unloading of bulk storage containers and drums using
EPA models. Details on this modeling approach are presented in Appendix A.2. EPA's modeled
exposure concentrations represent a larger range of potential inhalation exposure concentrations than
those presented by RIVM; thus, EPA uses these modeled exposures in lieu of using the monitoring data
or modeled exposure in the RIVM Annex XV Proposal for a Restriction - NMP report. The inhalation
monitoring data as well as the RIVM and EPA's modeled exposure concentrations are summarized and
further explained in Appendix A.2.
The inhalation exposure concentrations modeled by EPA for unloading of 100% NMP are summarized
into the input parameters used for the PBPK modeling in Table 2-7. The container unloading models
used by EPA calculates short-term exposure concentrations, with the exposure duration equal to the
duration of the unloading event (for bulk containers, typical case is 0.5 hours for unloading tank trucks
and worst-case is 1 hour for unloading rail cars; for drums, 20 containers are unloaded per hour and the
duration was determined based on the throughput of NMP at a site [refer to Appendix A.2 for further
explanation]) and number of loading events per day. EPA calculated the 8-hour TWA exposures to as
the weighted average exposure during an entire 8-hour shift, assuming zero exposures during the
remainder of the shift.
The Tank Truck and Railcar Loading and Unloading Release and Inhalation Exposure Model involves
deterministic modeling and the Drum Loading and Unloading Release and Inhalation Exposure Model
involves probabilistic modeling. See Appendix B.2 and B.3 for additional details on the bulk container
unloading modeling and the drum unloading modeling, respectively.
Table 2-7. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure
Repackaging
Full-Shift NMP
Duration-Based
Work
Activity
Parameter
Characterization
Air
NMP Air
Data
Concentration
Concentration
Source
Quality
(mg/m3, 8-hour
TWA)
(mg/m3)
Rating
Unloading
Central tendency
0.047
0.76 (duration =
Tank Truck and
NMP from
(50th percentile)
0.5 hour)
Railcar Loading and
Not
bulk
High-end (95th
0.19
1.52 (duration = 1
Unloading Release
applicable3
containers
percentile)
hour)
and Inhalation
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Work
Activity
Parameter
Characterization
Full-Shift NMP
Air
Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Exposure Model (U.S.
EPA. 2013a)
Unloading
NMP from
drums
Central tendency
(50th percentile)
0.427
1.65 (duration =
2.06 hour)
EPA OAOPS AP-42
Loading Model and
EPA/OPPTMass
Balance Model (U.S.
EPA. 2013a)
High-end (95th
percentile)
1.51
5.85 (duration =
2.06 hour)
a - EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically review models
that were developed by EPA.
2.2.2.3.2 Dermal
Table 2-8 summarizes the parameters used to assess dermal exposure during the repackaging of NMP
and formulations containing NMP. EPA assesses dermal exposure to NMP at the specified liquid weight
fraction, skin surface area, and exposure duration, based on the methodology described below. During
the importation and repackaging of NMP, EPA assessed dermal exposures during the unloading of pure
NMP from bulk containers and drums. See below for additional information.
NMP Weight Fraction
For this scenario, EPA gathered NMP concentration data from the non-CBI 2016 CDR results and
literature. The 2016 CDR results include 20 submissions with non-CBI concentration data that indicate
NMP is imported in formulations as low as less than one weight percent NMP and up to 90 to 100
weight percent NMP (U.S. EPA 2016a). One public comment indicates that NMP is imported in a
primer formulation at five weight percent NMP (Haas. 2017). Another source indicates NMP is
imported at a purity of 100 weight percent NMP (U.S. EPA 2012; TURI 1996). The underlying data
from all sources have overall confidence ratings of high. Based on this information, using the midpoint
when concentration data is available in a range, EPA calculated the 50th percentile weight percent of
NMP in imported products to be 95 weight percent. Based on the high 50th percentile NMP
concentration and EPA's expectation that bulk commodity chemicals are more likely to be repackaged
over formulations containing NMP (i.e., pure NMP is more likely to be repackaged than formulations
with lower NMP concentrations), EPA assesses dermal exposures at 100 weight percent NMP.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. Because repackaging of NMP occurs at industrial sites, EPA expects that the use of gloves is
likely (RIVM 2013). Workers are likely to wear protective gloves and have basic training on the proper
usage of these gloves, corresponding to a protection factor of 10 from Table 1-2 of Section 1.4.3.2.3.
Thus, EPA assesses a protection factor 10 for both the central tendency and high-end scenarios for this
scenario. EPA did not find data on the use of gloves for this occupational exposure scenario and the
glove protection factor assumptions are based on professional judgment. The assumed glove protection
factor values are highly uncertain.
Exposure Duration
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For the unloading of bulk containers, EPA assesses a central tendency exposure duration of half an hour,
based on the typical scenario assessed for inhalation exposures during the unloading of a tank truck and
rail car, respectively. For unloading of drums, EPA modeled the exposure duration to be 2.06 hours,
based on annual NMP throughput at each site (determined from the production volume and number of
sites from 2016 CDR), 250 days of operation per year, and an unloading rate of 20 drums per hour.
Refer to Appendix A.2 for additional information on this exposure duration calculation.
Table 2-8. Summary of Parameters for Worker Dermal Exposure to Liquids During Repackaging
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Unloading
NMP from bulk
containers
Central Tendency
10
1
445 (f)
535 (m)
0.5
74 (f)
88 (m)
High-end
10
1
890 (f)
1,070 (m)
1
Unloading
NMP from
drums
Central Tendency
10
1
445 (f)
535 (m)
2.06
74 (f)
88 (m)
High-end
10
1
890 (f)
1,070 (m)
2.06
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.2.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-9.
The numeric parameters corresponding to the characterizations presented in Table 2-9 are summarized
in Table 2-10. These are the inputs used in the PBPK model.
Table 2-9. Characterization of PBP
¦C Model Input Parameters for Repackaging
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Unloading
NMP from
bulk
containers
Central tendency
(50th percentile)
Duration
calculated
by model
1-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
High-end
Unloading
NMP from
drums
High-end (95th
percentile)
Duration
calculated
by model
2-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
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Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
0.76
0.5
445 (f)
535 (m)
10
1
74 (f)
88 (m)
High-end
5.85
2.06
890 (f)
1,070 (m)
10
1
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.2.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.3 Chemical Processing, Excluding Formulation
2.3.J_ Process Description
This scenario includes the use of NMP for processing activities other than formulation (i.e., non-
incorporative processing). Specifically, this may include the use of NMP as an intermediate, as a media
for synthesis, extractions, and purifications, or as some other type of processing aid. EPA identified the
following industries that use NMP in this manner (U.S. EPA 2016a; RIVM. 2013):
• Agricultural chemical manufacturing
• Petrochemical manufacturing
• Pharmaceutical manufacturing
• Polymer product manufacturing
• Miscellaneous chemical manufacturing
2.3.1.1 Agricultural Chemical Manufacturing
NMP is used for the manufacturing of agricultural chemicals, including fertilizers, fungicides,
insecticides, herbicides, and other types of pesticides (Abt 2017; U.S. EPA 2017b; RIVM. 2013). NMP
is used in the synthesis of active ingredients for agricultural chemicals (Roberts. 2017; RIVM. 2013). A
public comment to the NMP risk evaluation docket from the NMP Producers Group details that NMP is
used as a solvent in the production of a fertilizer additive that prevents the volatilization of urea in
fertilizer formulations (Roberts. 2017). The NMP Producers Group indicates that the amount of NMP in
the final fertilizer formulation is minimal (<0.1 percent). The RIVM Annex Xlr Proposal for a
Restriction - NMP report also indicates that, when NMP is used in the synthesis of active ingredients, it
is not expected to be in the final agricultural chemical formulation (RIVM. 2013).
NMP is also used in the formulation of agricultural chemicals such that it is present in the final
agricultural chemical formulation. Formulation activities are assessed in Section 2.4 of this risk
evaluation.
2.3.1.2 Petrochemical Manufacturing
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NMP is used as a petrochemical processing aid in a variety of applications including extraction of
aromatic hydrocarbons from lube oils; separation and recovery of aromatic hydrocarbons from mixed
hydrocarbon feedstocks; recovery of acetylenes, olefins and diolefins; removal of sulfur compounds
from and dehydration of natural gas and refinery gases (Anderson and Liu. 2000).
NMP is used both for the extraction of unwanted aromatics from lube oils and the recovery of
hydrocarbons from feedstocks, via extractive distillation (ERM. 2017; MacRov. .01"; MU J017;
RIVM. 2.013; ECHA. 2011). NMP is favorable for the extractive distillation of hydrocarbons because
hydrocarbons are highly soluble in NMP, and the use of NMP for extraction does not lead to the
formation of azeotropes.
Extractive distillation involves distillation in the presence of a solvent (or mixture of solvents) that acts
as a separating agent, displaying both a selectivity for and the capacity to solubilize components in a
mixture to be separated (Dohertv and Knapp. 2004). Solvents interact differently with the components of
the mixture to be separated, thereby altering their relative volatility and allowing them to be separated.
Solvents are added near the top of the extractive distillation column and the mixture to be separated is
added at a second feed point further down the column. The component with the higher volatility in the
presence of a solvent is distilled overhead as the distillate and components with lower volatility are
removed with the solvent in the column bottoms. The solvent is then separated from other components
of the mixture, generally through distillation in a second column, and then recycled back to the
extractive distillation column (Dohertv and Knapp. 2004).
Other uses of NMP in petrochemical processing involve using NMP to absorb specific compounds, then
separating the NMP from the absorbed compounds, similar to the extractive distillation process
(Anderson and Liu. 2000). Examples of absorptive processes include NMP use in the recovery of
acetylenes, olefins and diolefins; removal of sulfur compounds from natural and refinery gases; and the
dehydration of natural gas (MacRov. 2017; NIH. 2017; RIVM. 2013; Anderson and Liu. 2000).
Absorption using a solvent, such as NMP, generally involves two towers, an absorption tower and a
removal tower. The mixture to be separated and the solvent are first introduced into the absorption
tower. The solvent then absorbs the miscible compound and this heavier stream leaves in the bottoms of
the column. The solvent mixture is then sent to another column where the absorbed compound is
recovered from the solvent. The solvent may undergo further processes, such as scrubbing, to be fully
regenerated before being recycled back into the absorption column (Gannon and Schaffer. 2003).
2.3.1.3 Pharmaceutical Manufacturing
NMP is used as a solvent and extraction medium for the manufacture and formulation of
pharmaceuticals (ECHA.., 2011). The RIVM Annex XV Proposal for a Restriction - NMP report indicates
that NMP may be a reaction medium for the synthesis of antibiotics (RIVM. 2013). When NMP
functions as a reaction medium, it is not expected to be present above residual quantities in the final
product.
NMP may also be used in controlled release delivery systems for human and veterinary drugs, where
NMP is used as a solvent in which a biodegradable polymer housing the active drug is dissolved (RIVM.
2013).
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NMP has also historically been used as an excipient in pharmaceuticals, with potential function as a
transdermal enhancer (RIVM. 2013). However, the use of NMP in this function has since been banned
(NMP Producers Group. 2006).
2.3.1.4 Polymer Manufacturing
NMP is also used the polymer industry as a polymerization media for a variety of polymers.
NMP is used as a polymerization media for the manufacturing of polyphenylene sulfide (PPS) and other
high-temperature polymers such as polyethersulfones, polyamideimides and polyaramids (Materials.
2017; NIH. 2017; U.S. EPA. 2015b; RIVM. ). One public comment indicates that NMP is present
at below 17 ppm in produced PPS (Materials. 2017). Another public comment indicates that NMP may
be present at up to 1,500 ppm in resin pellets up to seven percent in resin powders (Roberts. 2017). EPA
expects that these quantities of NMP are driven off in subsequent compounding of the resins, which is
assessed in Section 2.4 of this risk evaluation.
Similarly, NMP is used as a processing aid in the production of polymer membranes (Roberts. iO I ;
RIVM. 2013). Polymer membranes are produced by immersion precipitation in which a solution of
polymer, solvents, and other additives is immersed in a water bath to produce a polymer-based film from
which the solvent is removed into the water bath. This film is isolated and solidified to produce the
desired membrane that can be applied in gas separations, filtrations, and desalination processes (RIVM.
2013). Further, a public comment on the NMP risk evaluation docket indicates polymer particles
dispersed in NMP may be imported into the US for the production of polymer film via a gravure process
( 'ftyroous. 2017). NMP is not present in the produced polymer membranes and films in appreciable
quantities (Anonymous. 2017; Roberts. 2017).
NMP is particularly useful for the dissolving and repolymerization of difficult to dissolve polymers
(ACC. 2017; RIVM. 2013). NMP can be used to dissolve polymers at elevated temperatures and
precipitate them to form beads and pellets (ACC. 2017). Additionally, NMP is used in this capacity to
produce high-performance polymers that are used for ballistic protection by dissolving the polymer and
allowing reaction between an amine group and a carboxylic acid halide group before polymerization
(RIV ). Again, NMP is not expected to be present above residual quantities in these products
(RIVM. 2013).
Finally, a comment on the NMP risk evaluation docket indicates that NMP can be used in the polymer
manufacturing industry as a polymerization inhibitor (Kemira. 2018). Specifically, NMP is used in
additives containing phenothiazine. According to this public comment, these additives can contain NMP
at 35 or 65 weight percent. In the case of uncontrolled polymerization, these additives are injected into
the reaction vessels to cease the polymerization reaction and prevent vessel ruptures. This comment
indicates that, if these additives are uses, NMP is not expected to be present in the final polymer articles.
2.3.1.5 Miscellaneous
NMP may be used in additional industries as a chemical intermediate. The exact process operations
involved during the use of NMP as a chemical intermediate are dependent on the final product that is
being synthesized. For NMP use as a chemical intermediate, operations would typically involve
unloading NMP from transport containers and feeding it into reaction vessel(s), where the NMP would
either react fully or to a lesser extent. Following completion of the reaction, the produced substance may
or may not be purified further, thus removing unreacted NMP (if present). The reacted NMP is not
expected to be released to the environment or to present a potential for worker exposure. Any unreacted
NMP presents potential sources of release or exposure.
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2.3.2 Exposure Assessment
2.3.2.1 Worker Activities
During the use of NMP as a reactant or other processing aid, workers are potentially exposed while
unloading NMP into intermediate storage or processing vessels, quality sampling of the NMP prior to
use, fugitive emissions from equipment leaks, and from maintenance and cleaning activities. These
activities are all potential sources of worker exposure through dermal contact, vapor-through-skin, and
inhalation of NMP vapors. For polymer processing, workers have further potential inhalation exposure
to NMP vapors during drying of the polymers as the NMP may evaporate as the produced polymer is
further processed or the NMP may be driven off with elevated temperatures (RIVM. 2013).
These processes are likely to be partially or fully closed operations, to avoid solvent losses (Roberts.
2017; RIVM. 2013) and due to the nature of the processes (i.e., extractions and other purification
processes are conducted in closed columns). One public comment indicates that workers who handle
solutions containing NMP wear a chemical resistant jacket, gloves, goggles, and a face shield (Kemira,
2.018). The RIVM Annex XV Proposal for a Restriction - NMP report recommends that workers within
these chemical processing industries wear gloves with an assigned protection factor (APF) of 5 (80
percent exposure reduction) (RIVM.! ). EPA did not find additional information on the use of
engineering controls and worker PPE at facilities that use NMP in non-incorporative processing
operations.
ONUs include employees that work at the site where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs include supervisors,
managers, and tradesmen that may be in the processing area but do not perform tasks that result in the
same level of exposures as workers.
2.3.2.2 Number of Potentially Exposed Workers
The use of NMP for non-incorporative processing operations may occur in many industries. EPA
determined the industries likely to use NMP for non-incorporative processing operations from the
following sources: the non-CBI 2016 CDR results for NMP ( 016a). 2016 TRI data (U.S.
), and the process descriptions in Section 2.3.1.
In the 2016 CDR, one submission reported processing of NMP as an intermediate in the plastic material
and resin manufacturing and pharmaceutical and medicine manufacturing industries (U.S. EPA. 2016a).
EPA identified three additional reported uses that EPA assessed in this scenario, including the use of
NMP as a processing aid in the following industries: petrochemical manufacturing (reported by two
submitters); pesticide, fertilizer, and other agricultural chemical manufacturing (reported by one
submitter); and, plastic material and resin manufacturing (reported by one submitter). Half of these
submissions report fewer than 10 sites that use NMP in non-incorporative activities, with the remaining
half reporting at least 10 but fewer than 25 sites. These submissions report varying estimates of the
number of workers potentially exposed. Due to the variability in the CDR reported values for number of
sites and workers and uncertainty in the basis of the CDR submitter estimates for downstream
processers, EPA estimated sites from 2016 TRI data and workers using data from the BLS and U.S.
Census Bureau.
EPA reviewed the 2016 TRI data for sites that use NMP as a reactant or as a chemical processing aid.
Based on the 2016 TRI data, 94 unique sites use NMP as a reactant and/or chemical processing aid. EPA
compiled the primary NAICS codes for these sites in Table 2-11. EPA determined the number of
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workers using the related SOC codes from BLS data that are associated with the primary NAICS codes
listed in Table 2-11. The method for estimating number of workers from the Bureau of Labor Statistics'
OES data and U.S. Census' SUSB data is detailed in Appendix B.l.
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Table 2-11. US Number of Establishments and Employees for Chemical Processing, Excluding Formulation
Number of
Establishments per
2016 TRI
Number of
Number of ONUs
2016
NAICS
2016 NAICS Title
Workers per Site
per BLS, 2016 and
per Site per BLS,
2016 and SUSB,
SUSB, 2015 Data3
2015 data8
313310
Textile and Fabric Finishing Mills
1
7
3
313320
Fabric Coating Mills
1
9
4
322299
All Other Converted Paper Product Manufacturing
1
21
3
323111
Commercial Printing (except Screen and Books)
1
2
1
323120
Support Activities for Printing
1
2
1
324110
Petroleum Refineries
4
170
75
325110
Petrochemical Manufacturing
1
64
30
325130
Synthetic Dye and Pigment Manufacturing
3
26
12
325199
All Other Basic Organic Chemical Manufacturing
7
39
18
325211
Plastics Material and Resin Manufacturing
6
27
12
325212
Synthetic Rubber Manufacturing
1
25
11
325220
Artificial and Synthetic Fibers and Filaments Manufacturing
1
47
21
325320
Pesticide and Other Agricultural Chemical Manufacturing
3
25
7
3254
Pharmaceutical and Medicine Manufacturing
9
41
25
325510
Paint and Coating Manufacturing
3
14
5
325520
Adhesive Manufacturing
1
18
7
325992
Photographic Film, Paper, Plate, and Chemical Manufacturing
1
19
6
325998
All Other Miscellaneous Chemical Product and Preparation Manufacturing
3
14
5
3261
Plastics Product Manufacturing
7
18
5
331420
Copper Rolling, Drawing, Extruding, and Alloying
3
32
10
332813
Electroplating, Plating, Polishing, Anodizing, and Coloring
2
8
2
333999
All Other Miscellaneous General Purpose Machinery Manufacturing
2
9
4
334400
Semiconductor and Other Electronic Component Manufacturing
12
30
27
334516
Analytical Laboratory Instrument Manufacturing
1
15
16
335911
Storage Battery Manufacturing
1
54
20
336100
Motor Vehicle Manufacturing
11
235
99
336300
Motor Vehicle Parts Manufacturing
3
51
15
339112
Surgical and Medical Instrument Manufacturing
1
34
11
339999
All Other Miscellaneous Manufacturing
3
5
1
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2016
NAICS
2016 NAICS Title
Number of
Establishments per
2016 TRI
Number of
Workers per Site
per BLS, 2016 and
SUSB, 2015 Data3
Number of ONUs
per Site per BLS,
2016 and SUSB,
2015 data8
Total establishments and number of potentially exposed workers and ONUs b=
94
5,400
2,500
a - Rounded to the nearest whole number.
b - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two significant figures.
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2.3.2.3 Occupational Exposure Assessment Methodology
2.3.2.3.1 Inhalation
EPA compiled inhalation monitoring data and modeled exposure concentrations for the use of NMP in
non-incorporative processing activities in Appendix A.3. The monitoring data included in this appendix
lacks data on worker activities, the function of NMP within the industry of use, and the sampling
duration; thus, EPA does not use these monitoring data. Due to limited relevance and quality of
monitoring data and modeling estimates for chemical processing with NMP found in the published
literature, EPA used modeling estimates with the highest data quality for this use, as described below.
In addition to the monitoring data, EPA compiled in Appendix A.3 the modeled NMP inhalation
exposure data that were presented in the RIVM Annex XV Proposal for a Restriction - NMP report
(RIVM. 2013). These modeled inhalation exposure concentrations are for the use of NMP as a process
solvent or reagent in an industrial setting and include scenarios for closed processing systems with
various levels of enclosure as well as the handling of NMP at both ambient and elevated temperatures.
Because the modeled exposure concentrations do not include loading and unloading operations, which
EPA expects to be a significant source of potential worker exposure, EPA modeled potential worker
inhalation exposure concentrations for the unloading of NMP from bulk containers (i.e., tank trucks and
rail cars) and drums. This modeling is consistent with the methodology described in Section 2.1.2.3.1 for
the manufacturing of NMP. The Drum Loading and Unloading Release and Inhalation Exposure Model
involves probabilistic modeling. Additional details on this modeling approach are presented in Appendix
A.3.
EPA used the short-term inhalation exposure concentration that EPA modeled during unloading of
drums containing 100% NMP as input to the PBPK model for short-term worker inhalation exposures.
The exposure duration for this short-term exposure scenario is the duration of the unloading event (20
drums are unloaded per hour and the duration was determined based on the throughput of NMP at a site
[refer to Appendix A.3 for further explanation]). These estimates are summarized in Table 2-12. EPA
calculated the 8-hour TWA exposures to as the weighted average exposure during an entire 8-hour shift,
assuming zero exposures during the remainder of the shift. See Appendix B.3 for additional details on
the drum unloading modeling.
Table 2-12. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Chemical Processing, Excluding Formulation
Work
Activity
Parameter
Characterization
Full-Shift NMP
Air
Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Unloading
liquid NMP
from drums
Central tendency
(50th percentile)
0.075
1.65 (duration =
0.36 hr)
Drum Loading and
Unloading Release
and Inhalation
Exposure Model
(U.S. EPA. 2013a)
Not
applicable3
High-end (95th
percentile)
0.265
5.85 (duration =
0.36 hr)
a - EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically review models
that were developed by EPA.
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2.3.2.3.2 Dermal
Table 2-13 summarizes the parameters used to assess dermal exposure during the use of NMP in non-
incorporative processing activities. EPA assesses dermal exposure to NMP at the specified liquid weight
fraction, skin surface area, and exposure duration, based on the methodology described below. During
the non-incorporative processing of NMP, workers are potentially exposed during sampling,
maintenance, unloading, and loading (packaging) activities. For this scenario, EPA assessed dermal
exposures during the unloading of pure NMP from drums. See below for additional information.
NMP Weight Fraction
For this scenario, EPA gathered NMP concentration data from the non-CBI 2016 CDR results, public
comments, and literature. The 2016 CDR results include seven submissions that indicate NMP is used as
an intermediate or non-incorporative processing aid (U.S. EPA 2016a). Six of these submissions
provide non-CBI concentration data, all indicating that NMP is used at 90 weight percent or greater.
Based on this information, EPA expects that chemical processors assessed in this scenario are likely to
purchase pure NMP and add to various processes in the amounts needed to achieve the desired
concentration for the process operation. Thus, EPA assesses dermal exposures for this scenario at 100
weight percent NMP. This data has an overall confidence rating of high.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. Because processing of NMP occurs at industrial sites, EPA expects that the use of gloves is likely
(RIVM 2013). Workers are likely to wear protective gloves and have basic training on the proper usage
of these gloves, corresponding to a protection factor of 10 from Table 1-2 of Section 1.4.3.2.3. Thus,
EPA assesses a protection factor 10 for both the central tendency and high-end scenarios for this
scenario. EPA did not find data on the use of gloves for this occupational exposure scenario and the
glove protection factor assumptions are based on professional judgment. The assumed glove protection
factor values are highly uncertain.
Exposure Duration
For unloading drums, EPA modeled the exposure duration to be 0.36 hours, based on the annual NMP
throughput at each site (determined by dividing the 2016 CDR production volume by the number of sites
for this and the Incorporation into Formulation, Mixture, or Reaction Product scenario), 250 days of
operation per year, and an unloading rate of 20 drums per hour. Refer to Appendix A.3 for additional
information on this exposure duration calculation.
Table 2-13. Summary of Parameters for Worker Dermal Exposure to Liquids During Chemical
Processing, Excluding Formulation
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Unloading
liquid NMP
from drums
Central Tendency
10
1
445 (f)
535 (m)
0.36
74 (f)
88 (m)
High-End
10
1
890 (f)
1,070 (m)
0.36
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
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2.3.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-14.
The numeric parameters corresponding to the characterizations presented in Table 2-14 are summarized
in Table 2-15. These are the inputs used in the PBPK model.
Table 2-14. Characterization of PBPK Model Input Parameters for Chemical Processing,
Excluding Formulation
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Unloading
drums
Central tendency
(50th percentile)
Duration
calculated
by model
1-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
High-end
Unloading
drums
High-end (95th
percentile)
Duration
calculated
by model
2-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
Table 2-15. PBPK Model Input Parameters for Chemical Processing, Excluding Formulation
Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
1.65
0.36
445 (f)
535 (m)
10
1
74 (f)
88 (m)
High-end
5.85
0.36
890 (f)
1,070 (m)
10
1
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.3.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.4 Incorporation into Formulation, Mixture, or Reaction Product
2.4J Process Description
Incorporation into a formulation, mixture or reaction product refers to the process of mixing or blending
of several raw materials to obtain a single product or preparation. The uses of NMP that may require
incorporation into a formulation include adhesives, sealants, paints, coatings, inks, metal finishing
chemicals, cleaning and degreasing products, agricultural products, and petrochemical products
including lube oils. NMP-specific formulation processes were not identified; however, several ESDs
published by the OECD and Generic Scenarios published by EPA have been identified that provide
general process descriptions for these types of products.
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The formulation of coatings and inks typically involves dispersion, milling, finishing and filling into
final packages (OB 10a. c). Adhesive formulation involves mixing together volatile and non-
volatile chemical components in sealed, unsealed or heated processes (OECD. 2009). Sealed processes
are most common for adhesive formulation because many adhesives are designed to set or react when
exposed to ambient conditions (OECD. 2009). Lubricant formulation typically involves the blending of
two or more components, including liquid and solid additives, together in a blending (OECD. 2017).
As described in Section 2.3.1.1, NMP is used in the formulation of agricultural products. While the
majority of these products are liquids, the NMP Producers Group provided a public comment to the
NMP risk evaluation docket indicating that a fertilizer additive is used to produce granular fertilizer
products (Roberts.! ). According to this public comment, the fertilizer additive containing NMP is
used in both liquid and granular fertilizer products and the blending of both the liquid and granular
fertilizers takes place in enclosed process equipment. The concentration of the NMP in the final fertilizer
product is expected to be less than 0.1 percent (Roberts. 2017). The "Preliminary Information on
Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document and 2017 market profile
on NMP also identify a granular fungicide product containing less than five weight percent NMP (Abt.
r!_ , \ lOiW.-VJ h).
As described in Section 2.3.1.4, NMP is used for the production of polymeric resins and may be present
in residual quantities from below 17 ppm (Materials. 2017) up to seven weight percent in the produced
resin (Roberts. 2017). The residual of seven percent is indicated for resin powders (Roberts. 2017). After
production, resins are typically compounded to produce a masterbatch. According to 2016 TRI data on
NMP, the compounding of resins is likely to occur at resin production sites, as opposed to at separate
compounding sites. In compounding, the polymer resin is blended with additives and other raw materials
to form a masterbatch in either open or closed blending processes (U.S. EPA. 2014). After
compounding, the resin is fed to an extruder where is it converted into pellets, sheets, films or pipes
(U.S. EPA.! ). These resin pellets and other shapes are then converted into final plastic articles,
generally by melting and forming or extruding, at plastic converting sites.
2.4.2 Exposure Assessment
2.4.2.1 Worker Activities
During the formulation of products containing NMP, workers are potentially exposed to NMP during
unloading of NMP, sampling, maintenance activities, and drumming or loading formulated products
containing NMP (RIVM. 2013). These activities are all potential sources of worker exposure through
dermal contact, vapor-through-skin, and inhalation of NMP vapors.
Several public comments to the NMP risk evaluation docket and literature sources report the use of
closed formulation processes. A public comment from FUJTFILM Electronic Materials (FFEM), which
formulates NMP products for the electronics industries, indicates that formulation is completed in an
enclosed process (Fuiifilm. 2017a). The NMP Producers Group provided a public comment indicating
that the blending of both liquid and granular fertilizers takes place in enclosed process equipment
(Roberts. 2017). Another comment from a coating and adhesive formulator indicates that products are
batch manufactured in an enclosed process (ACC. 2017). However, this comments also indicates that
metering of additives containing NMP may be done from open containers.
The Plastics Compounding GS indicates compounding of plastics may be done in either open or
enclosed vessels ( 014). The RIVM Annex XVProposal for a Restriction - NMP report on
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NMP indicates that formulation might or might not occur in closed processes and that formulation may
occur at elevated temperatures ( i. 2013). Another source on the formulation of paint stripping
products indicates that formulation of could be open or closed; however, closed processes are preferred
because they prevent solvent loss and mitigate exposures (White and Bardole. 2004).
Public comments indicate that respirators are used to prevent worker exposures to NMP (Roberts. 2017).
One public comment includes information from a formulator of coatings and adhesives, which indicates
that workers at that site wear full face respirators when handling NMP (ACC. 2017). One formulator of
products containing NMP indented for use in the electronics industry specifies that workers wear PPE,
including safety glasses, impervious gloves, and protective clothing with respirators, if needed (Fuiifilm.
2017a). Other literature sources indicate that workers generally wear safety glasses, impervious gloves,
and designated work clothes or overalls (Bader et at.. 2006; NICNAS. 2001). The RIVM Annex XI'
Proposal for a Restriction - NMP report recommends that workers within these formulation industries
wear gloves with an assigned protection factor (APF) of 5 (80 percent exposure reduction) (RIVM.
2013).
ONUs include employees that work sites where NMP is blended into formulations, but they do not
directly handle the chemical and are therefore expected to have lower exposures. ONUs for formulation
sites include supervisors, managers, and tradesmen that may be in the processing area, but do not
perform tasks that result in the same level of exposures as production workers.
2.4.2.2 Number of Potentially Exposed Workers
Formulation of NMP-based formulations, mixtures, and reaction products is widespread, occurring in
many industries. EPA determined the industries likely to conduct formulation activities using NMP from
the following sources: the non-CBI 2016 CDR results for NMP ( .016a). 2016 TRI data (U.S.
EPA. 2016b). the 2017 market profile for NMP (Abt 2017). the "Preliminary Information on
Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (' r \ -!0J_7h), and
public comments on the NMP risk evaluation docket.
In the 2016 CDR, 18 submissions reported processing of NMP by incorporation into a formulation,
mixture, or reaction product ( 2016a). More than half of these submissions report fewer than
10 sites that use NMP in incorporative activities, with the remaining submissions reporting a higher
estimate of sites or Not Known or Reasonably Ascertainable (NKRA). These submissions report varying
estimates of the number of workers potentially exposed, from fewer than 10 workers up to at least 500
but fewer than 1,000 workers. Due to the variability in the CDR reported values for number of sites and
workers and uncertainty in the basis of the CDR submitter estimates for downstream processers, EPA
estimated sites from 2016 TRI data and workers using data from the BLS and U.S. Census Bureau.
EPA reviewed the 2016 TRI data for sites that use NMP as a formulant. Based on the 2016 TRI data, 94
unique sites use NMP as a formulant. EPA compiled the primary NAICS codes for these sites in Table
2-16. EPA determined the number of workers using the related SOC codes from BLS analysis that are
associated with the primary NAICS codes listed in Table 2-16. The method for estimating number of
workers from the Bureau of Labor Statistics' OES data and U.S. Census' SUSB data is detailed in
Appendix B.l.
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Table 2-16. US Number of Establishments and Employees for Incorporation into Formulation, Mixture, or Reaction Product
Number of
Establishments per
2016 TRI
Number of
Number of ONUs
2016
NAICS
2016 NAICS Title
Workers per Site
per BLS, 2016 and
per Site per BLS,
2016 and SUSB,
SUSB, 2015 Data3
2015 data8
313320
Fabric Coating Mills
1
9
4
323111
Commercial Printing (except Screen and Books)
1
2
1
324191
Petroleum Lubricating Oil and Grease Manufacturing
1
20
9
325110
Petrochemical Manufacturing
1
64
30
325130
Synthetic Dye and Pigment Manufacturing
1
26
12
325180
Other Basic Inorganic Chemical Manufacturing
1
25
12
325199
All Other Basic Organic Chemical Manufacturing
5
39
18
325211
Plastics Material and Resin Manufacturing
9
27
12
325212
Synthetic Rubber Manufacturing
1
25
11
325220
Artificial and Synthetic Fibers and Filaments Manufacturing
1
47
21
325311
Nitrogenous Fertilizer Manufacturing
1
17
5
325314
Fertilizer (Mixing Only) Manufacturing
1
10
3
325320
Pesticide and Other Agricultural Chemical Manufacturing
9
25
7
325412
Pharmaceutical Preparation Manufacturing
1
44
27
325510
Paint and Coating Manufacturing
17
14
5
325520
Adhesive Manufacturing
4
18
7
325611
Soap and Other Detergent Manufacturing
2
19
4
325612
Polish and Other Sanitation Good Manufacturing
1
17
4
325910
Printing Ink Manufacturing
2
13
4
325992
Photographic Film, Paper, Plate, and Chemical Manufacturing
4
19
6
325998
All Other Miscellaneous Chemical Product and Preparation Manufacturing
12
14
5
3261
Plastics Product Manufacturing
2
18
5
326291
Rubber Product Manufacturing for Mechanical Use
1
43
7
331300
Alumina and Aluminum Production and Processing
1
33
13
331420
Copper Rolling, Drawing, Extruding, and Alloying
2
32
10
339112
Surgical and Medical Instrument Manufacturing
1
34
11
424690
Other Chemical and Allied Products Merchant Wholesalers
3
1
0
562211
Hazardous Waste Treatment and Disposal
7
9
5
562920
Materials Recovery Facilities
1
2
2
Total establishments and number of potentially exposed workers and ONUs b=
94
1,900
720
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a - Rounded to the nearest whole number.
b - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two significant figures.
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2.4.2.3 Occupational Exposure Assessment Methodology
2.4.2.3.1 Inhalation
EPA compiled inhalation monitoring data and modeled exposure concentration data for the
incorporation of NMP into a formulation, mixture, or reaction product in Appendix A.4. EPA favors the
use of monitoring data over modeled data, thus EPA used the monitoring data with the highest data
quality to assess exposure for this use, as described below.
Appendix A.4 includes NMP personal monitoring data during the formulation of adhesives, for workers
engaged in maintenance, cleaning, and packaging activities, which is summarized in Table 2-17. These
data also included area monitoring data in production and shipping areas, which is summarized in Table
2-18. EPA cannot distinguish ONU exposures from worker exposures from the data in Table 2-17 and
Table 2-18. EPA used the data in Table 2-17 for inhalation exposure inputs to the PBPK model, as
described in Section 2.4.3.
In addition to this monitoring data, EPA compiled in Appendix A.4 the modeled NMP inhalation
exposure data that were presented in the RIVM Annex XV Proposal for a Restriction - NMP report
(RIVM. 2013); however, EPA did not use modeled data from the RIVM Annex XV Proposal for a
Restriction - NMP report because EPA used monitoring data to assess these exposures. Consistent with
the modeling EPA described in Section 2.3.2.3.1 for the chemical processing (excluding formulation) of
NMP, EPA modeled potential worker inhalation exposures during the unloading of bulk storage
containers and drums containing 100% NMP. The Drum Loading and Unloading Release and
Inhalation Exposure Model involves probabilistic modeling. EPA used the inhalation exposure
concentrations that EPA modeled during unloading of drums containing pure NMP as input to the PBPK
model for central tendency worker exposure. The exposure duration for this short-term exposure
scenario is the duration of the unloading event (20 drums are unloaded per hour and the duration was
determined based on the throughput of NMP at a site [refer to Appendix A.4 for further explanation]).
EPA calculated the 8-hour TWA exposures to as the weighted average exposure during an entire 8-hour
shift, assuming zero exposures during the remainder of the shift. See Appendix B.3 for additional details
on the drum unloading modeling.
In addition to the formulation of liquid products, EPA identified formulation activities that may result in
potential worker exposures to particulates containing NMP. Specifically, these include plastics
compounding and blending of granular fertilizers, as described in Section 2.4.1. To determine potential
worker inhalation exposure to solids containing NMP, EPA used the OSHA permissible exposure limit
(PEL) for total particulates not otherwise regulated (PNOR) of 15 mg/m3 as an 8-hour TWA and NMP
concentration data in the products EPA identified as solids containing NMP that undergo formulation.
EPA does not use these exposure concentrations as input to the PBPK model because the PBPK model
does not account for solids, and the range of input parameters for the other exposure scenarios capture
these concentrations. See Appendix A.4 for additional details on this assessment.
Table 2-17. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Incorporation in
to Formulation,
Mixture, or React
tion Product
Work Activity
Parameter
Characterization
Full-Shift NMP
Air
Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
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Liquid -
unloading
drums
Central tendency
(50th percentile)
0.075
1.65 (duration =
0.36 hr)
Drum Loading
and Unloading
Release and
Inhalation
Exposure Model
Not
applicable3
Liquid -
Maintenance,
bottling,
shipping,
loading
High-end (95th
percentile)
12.8
No data
(Bader et al..
2006)
High
Solid - loading
into drums
Central tendency
(50th percentile)
0.75
No data
OSHA PNOR
PEL and NMP
concentration data
Not
applicable
High-end (95th
percentile)
0.96
No data
a - EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically review models
that were developed by EPA.
Table 2-18. Summary of Area Monitoring During Incorporation into Formulation, Mixture, or
Reaction Product
Scenario
Parameter
Characterization
Full-Shift NMP
Air Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Liquid -
Maintenance,
bottling, shipping,
loading
Central tendency
0.2
0.2
(Bader et
al.. 2006)
High
High-end
3
3
2.4.2.3.2 Dermal
Table 2-19 summarizes the parameters used to assess dermal exposure during the incorporation of NMP
into formulations, mixtures, and reaction products. EPA assesses dermal exposure to NMP at the
specified liquid weight fraction, skin surface area, and exposure duration, based on the methodology
described below. During the formulation of NMP, workers are potentially exposed during sampling,
maintenance, unloading, and loading activities. For this scenario, EPA assessed dermal exposures during
the unloading of pure NMP from drums. In addition, because NMP may be formulated into solid
products, EPA assessed the loading of solid formulations containing NMP into drums.
NMP Weight Fraction
NMP is most likely received at formulation sites in pure form (i.e., 100 weight percent NMP), before it
is unloaded by workers and formulated into products with various NMP concentrations. For this
scenario, EPA gathered NMP concentration data in formulated products from the non-CBI 2016 CDR
results, public comments to the NMP risk evaluation docket, the 2017 market profile for NMP, the
"Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document, and literature. The underlying data from these sources have overall confidence ratings
ranging from medium to high. The 2016 CDR results include 36 submissions that indicate NMP is used
for formulation in various industries, which formulate product ranging from at least one weight percent
up to at least 90 weight percent NMP (U.S. EPA 2016a). EPA reviewed the remaining data sources for
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the concentration of NMP in various formulations, including the products identified in all subsequent
scenarios except recycling and disposal. These products identify that NMP is present in formulations
ranging from 0.06 weight percent NMP up to 100 weight percent NMP (for industrial cleaning solvents).
For this scenario, EPA conservatively assessed dermal exposures during the unloading of pure NMP
from drums, which is the activity from which workers are potentially exposed to the highest
concentration of NMP.
Note that EPA also determined separate typical and worst-case NMP concentrations from seven
identified solid formulations (resins and granular agricultural products). EPA calculated the central
tendency (50th percentile) weight percent of NMP in solid formulations to be 5 weight percent and the
worst-case (95th percentile) to be 6.4 weight percent NMP.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. Because processing of NMP occurs at industrial sites, EPA expects that the use of gloves is likely
(RIVM 2013). Workers are likely to wear protective gloves and have basic training on the proper usage
of these gloves, corresponding to a protection factor of 10 from Table 1-2 of Section 1.4.3.2.3. Thus,
EPA assesses a protection factor 10 for both the central tendency and high-end scenarios for this
scenario. EPA did not find data on the use of gloves for this occupational exposure scenario and the
glove protection factor assumptions are based on professional judgment. The assumed glove protection
factor values are highly uncertain.
Exposure Duration
For unloading of drums containing NMP, EPA modeled the exposure duration to be 0.36 hours, based
on the annual NMP throughput at each site (determined by dividing the 2016 CDR production volume
by the number of sites for this and the previous scenario), 250 days of operation per year, and an
unloading rate of 20 drums per hour. Refer to Appendix A.4 for additional information on this exposure
duration calculation. EPA used this an exposure duration of 8 hours for the maintenance, bottling,
shipping, and loading of NMP because the exposure concentrations are 8-hour TWA values.
Table 2-19. Summary of Parameters for Worker Dermal Exposure to Liquids During
Incorporation into Formulation, Mixture, or
Reaction Proc
uct
Work Activity
Parameter
Characterization
Glove
Protection
Factor (s)
NMP
Weight
Fraction
Skin
Surface
Area
Exposed a
Exposure
Duration
Body
Weight
a
Unitless
cm2
hr/day
kg
Liquid - Unloading
drums
Central Tendency
10
1
445 (f)
535 (m)
0.36
74 (f)
88 (m)
Liquid -
Maintenance,
bottling, shipping,
loading
High-End
10
1
890 (f)
1,070 (m)
8
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.4.3 PBPK Inputs
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Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-20.
EPA only presents these scenarios for handling of liquid NMP, to present the most conservative
assessment of potential exposures.
The numeric parameters corresponding to the characterizations presented in Table 2-20 are summarized
in Table 2-21. These are the inputs used in the PBPK model.
Table 2-20. Characterization of PBPK Model Input Parameters for Incorporation into
Formulation, Mixture, or Reaction Product
Scenario
Work Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Liquid - Drum
unloading
Central tendency
(50th percentile)
Duration
calculated
by model
1-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
High-end
Liquid -
Maintenance,
bottling,
shipping,
loading
High-end (95th
percentile)
Duration
calculated
by model
2-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
Table 2-21. PBPK Model Input Parameters for Incorporation into Formulation, Mixture, or
Reaction Product
Scenario
Activity
Duration-
Based NMP
Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
Liquid -
Drum
unloading
1.65
0.36
445 (f)
535 (m)
10
1
74 (f)
88 (m)
High-end
Liquid -
Maintenance,
bottling,
shipping,
loading
12.8
8
890 (f)
1,070 (m)
10
1
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.4.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
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2.5 Metal Finishing
2.5.1 Process Description
EPA's "Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document indicates that NMP is used in metal finishing operations (U.S. EPA. 2017b). Metal finishing
is a broad term used in industry to include a wide variety of processes that alter the surface of metal
substrates, such as cleaning, coating, etching, and invasive quality testing.
Prior to any metal finishing process, the surfaces of metal substrates must first be cleaned to remove
grease and other surface contamination (OECD. 2004). Following cleaning, the substrates may then be
conditioned or activated, which involves the use of a dilute acid to neutralize any remaining alkaline
cleaner used in the cleaning process and to dissolve any tarnish or oxide film on the surface of the metal
substrates. Further, to produce the required surface smoothness or texture, facilities often use polishing
and other abrasive techniques. NMP is expected to be used in these types of surface preparation
processes.
In addition to surface preparation, the Consumer Specialty Products Association (CSPA) submitted a
public comment to EPA's NMP docket indicating that NMP is used as a penetrant for inspection of
metals, specifically on metal parts such as those used in turbines and bridges, among other types of parts
(Brown and Bennett 2017). Penetrants contain dyes and are used to identify defects in metal parts, such
as those from fatigue and welding cracks. Specifically, once parts are machined and assembled,
penetrant is applied to the surface of the metal, where it migrates into cracks and other surface defects.
The metal parts are then visually inspected for defects, frequently under an ultraviolet light where
fluorescent penetrant dyes are more visible, and then the penetrant is cleaned from the metal part
(Center. ).
The specific process steps depend on the type of substrate with application methods including: dip or
immersion, spray, roll, and brush application.
Based on the above information, EPA expects NMP is used in surface preparation and invasive testing
of metal parts. Therefore, EPA assesses the following distinct occupational exposure scenarios for this
scenario:
• Spray application
• Dip application
• Brush application
NMP may also be used in coatings that are applied to metal parts; however, coating processes with
NMP-based products are covered in Section 2.5.
2.5.2 Exposure Assessment
2.5.2.1 Worker Activities
Workers are potentially exposed to NMP in metal finishing formulations during multiple activities,
including quality testing of formulations, transferring the formulations into application equipment (if
used), applying the formulation to a substrate, and maintenance and cleaning activities. These activities
are all potential sources of worker exposure through dermal contact, vapor-through-skin, and inhalation
of NMP vapors.
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During application of metal finishing formulations, workers may manually apply the formulation with a
variety of application techniques, including spray application from a handheld spray gun or can, brush
application, and dipping. All types of application are potential exposure points for workers. Some
application methods may be automated, which reduces the potential for worker exposures. For example,
for larger metal parts, machinery may be used to dip these parts into metal finishing formulations. If the
dip application apparatus has an enclosed reservoir, this reduces the potential for NMP vapors to escape
and become available for worker inhalation exposure. The extent of automated application processes and
use of open versus closed systems in the various industries that conduct metal finishing operations is
unknown.
The German Institute for Occupational Safety and Health (IFA) compiled monitoring data for multiple
industries that use NMP, including foundries (IF 2010). EPA has not identified information describing
how NMP is used at the foundry companies that were included in this monitoring data compilation.
However, EPA believes these operations are most likely to fall within this scenario. These data include
samples from facilities that employ LEV, indicating that this engineering control is sometimes used at
facilities that conduct metal finishing operations. EPA did not find information regarding the frequency
of use of this or other engineering controls nor that for worker PPE in the various industries that may
conduct metal finishing operations.
ONUs include employees that work at the sites where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
supervisors, managers, and other employees that may be in the production areas but do not perform tasks
that result in the same level of exposures as those workers that engage in tasks related to the use of
NMP.
2.5.2.2 Number of Potentially Exposed Workers
Application of NMP-based metal finishing products may occur in multiple industries. EPA determined
the industries likely to use NMP for metal finishing from the non-CBI 2016 CDR results for NMP (U.S.
16a). the Scope of the Risk Evaluation for N-Methylpyrrolidone (U.S. EPA. 2017c). and the
public comment from the CSPA (Brown and Bennett. 2017).
The exact industries that distinctly perform metal finishing operations are unknown. EPA compiled the
associated NAICS codes for the identified industries in Table 2-22. EPA determined the number of
workers associated with each industry using Bureau of Labor Statistics' OES data (tiS, Bl-S. 2016) and
the U.S. Census" SUSB ( isus Bureau. 2015). The number of establishments within each industry
that use NMP-based metal finishing products and the number of employees within an establishment
exposed to these NMP-based products are unknown. Therefore, EPA provides the total number of
establishments and employees in these industries as bounding estimates of the number of establishments
that use and the number of employees that are potentially exposed to NMP-based metal finishing
products. These bounding estimates are likely overestimates of the actual number of establishments and
employees potentially exposed to NMP during metal finishing.
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Table 2-22. US Number of Establishments and Employees for Metal Finishing
2016
NAICS
Number of
Number
of
Workers
per Sitea
Number of
Industry
Source
2016 NAICS Title
Establishment
s
ONUs per
Site3
331100
Iron and Steel Mills and Ferroalloy Manufacturing
603
55
21
Primary Metal
Manufacturing
331200
Steel Product Manufacturing from Purchased Steel
667
34
10
(IFA. 2010)
331300
Alumina and Aluminum Production and Processing
529
37 b
15 b
331400
Nonferrous Metal (except Aluminum) Production and
Processing
964
28
10
331500
Foundries
1,770
18
10
332100
Forging and Stamping
2,467
11
5
332200
Cutlery and Handtool Manufacturing
1,194
8
3
332300
Architectural and Structural Metals Manufacturing
12,309
11
4
Fabricated
Metal Product
Manufacturing
332400
Boiler, Tank, and Shipping Container Manufacturing
1,575
21
8
(U.S. EPA
332500
Hardware Manufacturing
599
12
4
2016a)
332600
Spring and Wire Product Manufacturing
1,196
11
4
332700
Machine Shops; Turned Product; and Screw, Nut, and Bolt
Manufacturing
23,083
2
2
332800
Coating, Engraving, Heat Treating, and Allied Activities
5,732
11
4
332900
Other Fabricated Metal Product Manufacturing
6,612
12
6
Turbine
Manufacturing
(Brown and
Bennett. 2017)
333600
Engine, Turbine, and Power Transmission Equipment
Manufacturing
1,073
30
17
Total establishments and number of potentially exposed workers and ONUs =c
60,000
530,000
190,000
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest whole number.
b - No 2016 BLS data was available for this NAICS. Number of relevant workers per site and ONUs per site within this NAICS were calculated using the ratios of
relevant workers and ONUs to the number of total employees at the 3-digit NAICS level.
c - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two significant figures.
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2.5.2.3 Occupational Exposure Assessment Methodology
2.5.2.3.1 Inhalation
Appendix A.5 summarizes the inhalation monitoring data for NMP-based metal finishing application
that EPA compiled from published literature sources, including 8-hour TWA, short-term, and partial
shift sampling results. This appendix also includes EPA's rationale for inclusion or exclusion of these
data in the risk evaluation, as well as description of any modeling approaches used by EPA to assess
exposures in this scenario. In summary, where available, EPA used the monitoring data for metal
finishing or surrogate monitoring data for the use of NMP during Application of Paints, Coatings,
Adhesives, and Sealants and Cleaning that had the highest quality rating to assess exposure. Where
monitoring data was unavailable for an application type, EPA used modeling estimates with the highest
data quality to assess exposure. This is further described below.
EPA found limited data on the application of metal finishing chemicals, thus assesses spray application
using the data from Application of Paints, Coatings, Adhesives, and Sealants (refer to Section 2.5) as
surrogate (surrogate work activities using NMP) for this scenario. EPA used data for dip cleaning from
the Cleaning scenario (refer to Section 2.10) as surrogate (surrogate work activities using NMP) for this
scenario. Finally, EPA used a modeled exposure for the brush application of a substance containing
NMP that was presented in the RIVM Annex XV Proposal for a Restriction - NMP report. The personal
breathing zone monitoring data and the modeled exposures are summarized in Table 2-23. The area
monitoring data are summarized in Table 2-24. EPA cannot distinguish ONU exposures from worker
exposures from the data in Table 2-23 and Table 2-24. EPA used the data in Table 2-23 for inhalation
exposure inputs to the PBPK model, as described in Section 2.5.3.
Table 2-23. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Metal Finishing
Full-Shift NMP
Duration-Based
Work
Activity
Parameter
Characterization
Air
NMP Air
Data
Concentration
Concentration
Source
Quality
(mg/m3, 8- hour
TWA)
(mg/m3)
Rating
Low-end (of range)
0.040
0.040 (duration =
4 hr)
Spray
Application
Mean
0.530
0.530 (duration =
4 hr)
(NIOSH. 1998)
High
High-end (of
4.51
4.51 (duration = 4
range)
hr)
Surrogate data
Central tendency
(50th percentile)
0.990
No data
(surrogate work
activities using NMP)
Dip
from: (RIVM. 2013;
Medium
Application
Nishimura et al.. 2009;
to high
High-end (95th
percentile)
2.75
No data
Bader et al.. 2006) (IFA.
2010; Xiaofei et al..
2000)
Brush
Application
Single estimate
4.13
No data
(RIVM. 2013)
High
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Table 2-24. Summary of Area Monil
oring During Metal Finishing
Work
Activity
Parameter
Characterization
Full-Shift NMP
Air
Concentration
Duration-Based NMP
Air Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Spray
Application
Low-end
0.040
0.040 (duration = 4 hr)
(NIOSH.
1998)
High
Mean
0.140
0.140 (duration = 4 hr)
High-end
0.530
0.530 (duration = 4 hr)
2.5.2.3.2 Dermal
Table 2-25 summarizes the parameters used to assess dermal exposure during application of metal
finishing formulations containing NMP. EPA assesses dermal exposure to NMP at the specified liquid
weight fraction, skin surface area, and exposure duration.
NMP Weight Fraction
Neither the 2017 Market Profile for NMP (Abt 2017) nor the "Preliminary Information on
Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (U.S. EPA 2017b)
identified metal finishing products containing NMP. The 2012 and 2016 CDR results indicate industrial
and commercial categories of use for "metal products not covered elsewhere." These categories of use
indicate that the weight concentration of NMP in formulation is greater than 60 percent but less than 90
percent. Due to lack of additional information, EPA assesses a low-end weight fraction of 0.6 and a
high-end weight fraction of 0.9. Because metal finishing products can be applied with multiple different
methods (e.g., spray and brush), EPA assesses these weight fractions for all application methods in this
scenario. These data have overall confidence ratings of high.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. EPA did not find information on the use of gloves within the metal finishing industries. Thus,
EPA assesses that no gloves are used for the high-end exposure scenario, corresponding to a protection
factor of 1 from Table 1-2 of Section 1.4.3.2.3. EPA expects that workers may potentially wear gloves
but does not know the likelihood that workers wear gloves of the proper material and have training on
the proper usage of gloves. No information on employee training was found, but due to the commercial
nature of this use, EPA expects minimal to no employee training. Based on this information EPA
assesses a central tendency protection factor of 5 from Table 1-2 of Section 1.4.3.2.3. EPA did not find
data on the use of gloves for this occupational exposure scenario and the glove protection factor
assumptions are based on professional judgment. The assumed glove protection factor values are highly
uncertain.
Exposure Duration
EPA did not find data on exposure duration. As described in Section 1.4.3.2.4, EPA assumes a high-end
exposure duration of eight hours and a central tendency exposure duration of four hours.
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Table 2-25. Summary of Parameters for Worker Dermal Exposure to Liquids During Metal
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
All forms of
application
listed above
Central Tendency
5
0.6
445 (f)
535 (m)
4
74 (f)
88 (m)
High-End
1
0.9
890 (f)
1,070 (m)
8
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.5.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-26.
The numeric parameters corresponding to the characterizations presented in Table 2-26 are summarized
in Table 2-27. These are the inputs used in the PBPK model.
Table 2-26. Characterization of PBPK Model Input Parameters for Metal Finishing
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Spray
application
Mean
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Spray
application
High-end (of range)
Assumed 8
hours
2-hand
No
High-end
Central
Tendency
Dip
application
Central tendency
(50th percentile)
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Dip
application
High-end (95th
percentile)
Assumed 8
hours
2-hand
No
High-end
Central
Tendency
Brush
application
Single estimate
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Brush
application
Single estimate
Assumed 8
hours
2-hand
No
High-end
Table 2-27. PBPK Model Input Parameters for Metal Finishing
Scenario
Activity
Duration-
Based NMP
Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2)a b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
Spray
application
0.530
4
445 (f)
535 (m)
5
0.6
74 (f)
88 (m)
High-end
Spray
application
4.51
8
890 (f)
1,070 (m)
1
0.9
74 (f)
88 (m)
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Scenario
Activity
Duration-
Based NMP
Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
Dip
application
1.98
4
445 (f)
535 (m)
5
0.6
74 (f)
88 (m)
High-end
Dip
application
2.75
8
890 (f)
1,070 (m)
1
0.9
74 (f)
88 (m)
Central Tendency
Brush
application
8.26
4
445 (f)
535 (m)
5
0.6
74 (f)
88 (m)
High-end
Brush
application
4.13
8
890 (f)
1,070 (m)
1
0.9
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.5.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.6 Removal of Paints, Coatings, Adhesives, and Sealants
2.6.1 Process Description
EPA's 2017 market profile of NMP identified that NMP may be used in removers for paints, coatings,
and adhesives (Abt 2017). Similar to the 2015 EPA Assessment on Paint Stripper Use (U.S. EPA
2015b). this risk evaluation considers two different occupational exposure scenarios within this category
of use: miscellaneous stripping, which is assumed to occur mostly indoors, and graffiti removal, which
is assumed mostly outdoor but may include partially enclosed spaces, such as outdoor escalators and
elevators. EPA makes this distinction based on the specificity of the available monitoring data.
The typical process for removal of paints and coatings, including graffiti removal, from substrates first
includes optional preparation of surfaces via cleaning and sanding (U.S. EPA 2015b). This preparation
is to ensure that the removal product will stick to the coating to be removed. Following surface
preparation, the paint and coating removal product is applied to the surface of the substrate via hand-
held brush, tank dipping, spray application, pouring, wiping, or rolling. Depending on whether removal
is performed industrially or commercially, users may purchase paint and coating removal products in
55-gallon drums or in common, commercially available containers that range from 1 liter to 5 gallons
(U.S. EPA 2015b).
Paint stripper application methods can include brushing, spraying, dipping, and wiping (White and
Bardole. 2004). The particular application method is dependent on the size and location of the substrate.
For example, for walls and floors, the removal product is typically applied with a handheld brush. For
furniture, the furniture pieces are generally dipped into a tank containing the removal product, or the
removal product is applied by brushing or spraying. After application, the stripper is allowed to set and
soften the old coating (U.S. EPA 2015b). The old coating is then removed by scraping, brushing,
wiping, or mechanically buffering or sanding. Once the old coating is removed, the substrate may be
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washed with water or solvent to remove any remaining portions of the old coating and prepare the
surface for a new coating, if one is to be applied.
2.6.2 Exposure Assessment
2.6.2.1 Worker Activities
During paint and coating removal, workers may manually apply the removal product to the surface of
the substrate. Once the paint and coating removal product is applied to the substrate and allowed to set,
workers will likely manually remove the old coating. Both these worker activities are potential sources
of worker exposure, through dermal contact, vapor-through-skin, and inhalation of NMP vapors.
EPA did not find information on the customary engineering controls and worker PPE used in the paint,
coating, and graffiti removal industries; however, some resources list suggested engineering controls and
worker PPE that may be used during paint, coating, and graffiti removal. Graffiti removal is typically
performed outdoors, while paint and coating removal may occur indoors or outdoors. Should removal
activities occur indoors, the area may be mechanically ventilated (U.S. EPA. 2013b). Workers may wear
respirators to reduce potential exposure to NMP vapors. Workers may wear gloves that are resistant to
NMP, which include butyl rubber and laminated polyethylene or ethylene vinyl alcohol (EVOH) gloves.
The 2015 EPA ( ) for NMP assesses exposures considering the use of gloves that have
an exposure reduction efficiency of 90 percent and the use of respirators with an assigned protection
factor (APF) of 10 ( ). The RA also assesses exposures without consideration for gloves
or respirators, as EPA had not identified information indicating these PPE are generally implemented
across all industries that conduct paint and coating removal.
ONUs include employees that work at the sites where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
supervisors, managers, and other employees that may be in the production areas but do not perform tasks
that result in the same level of exposures as those workers that engage in tasks related to the use of
NMP.
2.6.2.2 Number of Potentially Exposed Workers
The 2015 EPA Assessment on Paint Stripper Use ( ) identified the following industries
that are likely to conduct paint stripping activities:
• Professional contractors;
• Bathtub refinishing;
• Automotive refinishing;
• Furniture refinishing;
• Art restoration and conservation;
• Aircraft paint stripping;
• Ship paint stripping; and
• Graffiti removal.
EPA's additional research does not indicate that this list of industries has changed since publication of
the 2015 Paint Stripper Risk Assessment. EPA determined the number of workers associated with each
industry using Bureau of Labor Statistics" OES data ( I. 2016) and the U.S. Census" SUSB (U.S.
Census Bureau. 2015). These data are summarized in Table 2-28. The number of establishments within
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each industry that use NMP-based removal products and the number of employees within an
establishment exposed to NMP-based removal products are unknown. Therefore, EPA provides the total
number of establishments and employees in these industries as bounding estimates of the number of
establishments that use and the number of employees that are potentially exposed to NMP-based
removal products. These bounding estimates are likely overestimates of the actual number of
establishments and employees potentially exposed to NMP during paint and coating removal.
Table 2-28. US Number of Establishments and Employees for Removal of Paints, Coatings,
Adhesives, and Sealants
Occupational
Exposure
Scenario
2016
NAICS
2016 NAICS Title
Number of
Establishments
Number
of
Workers
Site a
Number
of
ONUs
per Site
a
Miscellaneous
Paint,
Coating,
Adhesive, and
Sealant
Removal
238320
Painting and Wall Covering
Contractors
31,943
4
0
238330
Flooring Contractors
14,601
4
0
811121
Automotive Body, Paint and
Interior Repair and Maintenance
33,648
3
0
811420
Reupholstery and Furniture Repair
3,720
1
1
711510
Independent Artists, Writers and
Performers
25,205
1
0
712110
Museums
5,125
1
0
336411
Aircraft Manufacturing
321
187
159
336611
Ship building and repairing
674
62
22
Graffiti
Removal
Unknown
Total number of establishments, workers, and ONUs
potentially exposed b
120,000
410,000
100,000
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest worker.
b - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.6.2.3 Occupational Exposure Assessment Methodology
EPA evaluated potential worker exposures through PBPK modeling. The PBPK model was used to
calculate internal doses of NMP using a set of parameters determined from literature or through standard
assumptions, as described below.
2.6.2.3.1 Inhalation
Appendix A.6 summarizes the inhalation monitoring data for NMP-based paint and coating removal that
EPA compiled from published literature sources, including 8-hour TWA, short-term, and partial shift
sampling results. This appendix also includes EPA's rationale for inclusion or exclusion of these data in
the risk evaluation. EPA used the available monitoring data with the highest data quality to assess
exposure for this use.
The available monitoring data for paint and coating removal are summarized into low-end (lowest
concentration), high-end (highest concentration), and mean or mid-range values in Table 2-29. Note
that, where possible, EPA prefers to present a central tendency (based on 50th percentile) and worst-case
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(based on 95th percentile) exposure scenario. However, due to lack of data, EPA summarized the data
into low-end, high-end, and mid-range or mean.
EPA's research for this risk evaluation did not result in additional 8-hour TWA data points from the
2015 TSCA Work Plan Chemical Risk Assessment N-Methylpyrrolidone: Paint Stripping Use (U.S.
EPA 2015b). The data presented in Table 2-29 are the input parameters used for the PBPK modeling for
workers and ONUs, respectively. Note that, due to lack of specificity in the monitoring data, EPA
assumes the data are representative of both workers and ONUs.
Table 2-29. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Removal of Paints, Coatings, Adhesives, and Sealants
Work Activity
Parameter
Characterization
Full-Shift NMP
Air
Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Miscellaneous paint,
coating, adhesive, and
sealant removal
Low-end (of range)
1.0
6.1 (duration = 1 hr)
(U.S.
EPA.
2015b)
High
Mid-range
32.5
13.2 (duration = 1
hr)
High-end (of range)
64
280 (duration = 1
hr)
Graffiti removal
Low-end
0.03
No data
(U.S.
EPA.
2015b)
High
Mean
1.01
No data
High-end
4.52
No data
2.6.2.3.2 Dermal
Table 2-30 summarizes the parameters used to assess dermal exposure during paint and coating removal.
EPA assumed that the skin was exposed dermally to NMP at the specified liquid weight fraction, skin
surface area, and exposure duration, based on the methodology described below.
NMP Weight Fraction
The 2015 EPA Assessment on Paint Stripper Use (U.S. EPA 2015b) identified the weight percent of
NMP in paint and coating removal products as ranging from 25 up to 100. EPA identified additional
paint stripping and graffiti removal products in the 2017 market profile on NMP and "Preliminary
Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (Abt
2017; U.S. EPA 2017b). This data identified multiple commercial and industrial grade paint, coating,
and graffiti removers that contain NMP at weight fractions ranging from 1 to 100 weight percent NMP.
With these data, EPA determined a typical and worst-case estimate of NMP concentration in these
products, calculated as the 50th percentile and 95th percentile, respectively. Where NMP concentration
was provided in a range, EPA used the midpoint of the range for the calculations. Based on these data,
for miscellaneous paint, coating, adhesive, and sealant removal, the typical NMP concentration is 30.5
weight percent and the worst-case NMP concentration is 69.5 weight percent. For graffiti removal, the
typical NMP concentration is 50 weight percent and the worst-case NMP concentration is 61.25 weight
percent. The underlying data used for these estimates have overall confidence ratings ranging from
medium to high.
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For the remaining dermal parameters, skin surface area, exposure duration, and body weight, EPA uses
the same methodology for both miscellaneous removal and graffiti removal, as described below.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. The 2015 EPA (U.S. EPA 2015b) for NMP assesses exposures considering the use of gloves that
have an exposure reduction efficiency of 90 percent, equal to a protection factor of 10 (U.S. EPA
2015b). The RA also assesses exposures without consideration for gloves or respirators, as EPA had not
identified information indicating these PPE are generally implemented across all industries that conduct
paint and coating removal. Consistent with the RA and due to the wide-spread use of NMP-based paint
and coating removal products, EPA assumes that no gloves are used for the worst-case exposure
scenario, corresponding to a protection factor of 1. The 2015 EPA (U.S. EPA 2015b) assumed that, if
gloves were worn, they provided a protection factor of 10. However, for this risk evaluation, EPA
considers the potential for employee training on proper glove usage. No information on employee
training was found, but due to the commercial nature of this use, EPA expects minimal to no employee
training. Based on this information EPA assesses a central tendency protection factor of 5 from Table
1-2 of Section 1.4.3.2.3. EPA did not find data on the use of gloves for this occupational exposure
scenario and the glove protection factor assumptions are based on professional judgment. The assumed
glove protection factor values are highly uncertain.
Exposure Duration
For paint and coating removal, EPA found inhalation exposure monitoring data indicating an exposure
duration of one hour. EPA uses this duration as a central tendency scenario. For a high-end scenario, as
described in Section 1.4.3.2.4, EPA assumes eight hours. For graffiti removal, EPA did not find data on
exposure duration. As described in Section 1.4.3.2.4, EPA assumes a high-end exposure duration of
eight hours and a central tendency exposure duration of four hours.
Table 2-30. Summary of Parameters for PBPK Modeling of Worker Dermal Exposure to Liquids
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin
Surface
Area
Exposed a
Exposure
Duration
Body
Weight
a
Unitless
cm2
hr/day
kg
Miscellaneous paint,
coating, adhesive,
and sealant removal
Central Tendency
5
0.305
445 (f)
535 (m)
1
74 (f)
High-End
1
0.695
890 (f)
1,070 (m)
8
88 (m)
Graffiti removal
Central Tendency
5
0.5
445 (f)
535 (m)
4
74 (f)
High-End
1
0.6125
890 (f)
1,070 (m)
8
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.6.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-31.
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The numeric parameters corresponding to the characterizations presented in Table 2-31 are summarized
in Table 2-32. These are the inputs used in the PBPK model.
Table 2-31. Characterization of PBPK Model Input Parameters for Removal of Paints, Coatings,
Adhesives, and Sealants
Scenario
Work Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Miscellaneous
paint, coating,
adhesive, and
sealant removal
Mid-range
Based on
1-hour
TWA data
1-hand
Yes
Central Tendency
High-end
Miscellaneous
paint, coating,
adhesive, and
sealant removal
High-end (of range)
Assumed 8
hours
2-hand
No
High-end
Central
Tendency
Graffiti removal
Mean
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Graffiti removal
High-end (of range)
Assumed 8
hours
2-hand
No
High-end
Table 2-32. PBPK Model Input Parameters for Removal of Paints, Coatings, Adhesives, and
Sealants
Scenario
Activity
Duration-
Based NMP
Air
Concentratio
n (mg/m3)
Exposur
e
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protectio
n Factor
NMP
Weight
Fr actio
n
Body
Weigh
t(kg)a
Miscellaneou
Central
Tendency
s paint,
coating,
adhesive, and
sealant
removal
13.2
1
445 (f)
535 (m)
5
0.305
74 (f)
88 (m)
Miscellaneou
High-end
s paint,
coating,
adhesive, and
64
8
890 (f)
1,070
(m)
1
0.695
74 (f)
88 (m)
sealant
removal
Central
Graffiti
2.02
A
445 (f)
0.5
74 (f)
Tendency
removal
4
535 (m)
88 (m)
High-end
Graffiti
removal
4.52
8
890 (f)
1,070
(m)
1
0.6125
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
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2.6.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.7 Application of Paints, Coatings, Adhesives, and Sealants
2.7.1 Process Description
Based on information identified in the "Preliminary Information on Manufacturing, Processing,
Distribution, Use, and Disposal: NMP" document and 2016 CDR reporting, NMP is used as a solvent in
a wide variety of industrial, commercial, and consumer paints, coatings, adhesives, and sealants (
EPA. 2017b. 2016a). The application methods vary with the specific use.
Several OECD ESDs and EPA generic scenarios provide general process descriptions and worker
activities for industrial and commercial uses. The ESD on Radiation Curable Coatings, Inks, and
Adhesives indicates that, before application onto substrates, paint and coating formulations may be
diluted and are then charged into application equipment (OECD. 2011). Typical coating applications
include manual application with roller or brush, air spray systems, airless and air-assisted airless spray
systems, electrostatic spray systems, electrodeposition/electrocoating and autodeposition, dip coating,
curtain coating systems, roll coating systems, and supercritical carbon dioxide systems (OE 11).
After application, solvent-based coatings typically undergo a drying stage in which the solvent
evaporates from the coating (OECD. 2011).
The OECD ESD for Use of Adhesives (OECD. 2015) provides general process descriptions and worker
activities for industrial adhesive uses. Liquid adhesives are unloaded from containers into the coating
reservoir, applied to a flat or three-dimensional substrate, and the substrates are then joined and allowed
to cure (J ). The majority of adhesive applications include spray, roll, curtain, and syringe or
bead application (OECD. 2015). For solvent-based adhesives, the volatile solvent (in this case NMP)
evaporates during the curing stage (OECD. 2015). Based on EPA's knowledge of the industry, EPA
expects similar process descriptions, worker activities, and application methods for sealant products as
those described above.
Based on the types of paint, coating, adhesive, and sealant products listed in the "Preliminary
Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (U.S.
17b) and 2017 market profile on NMP (AM. 2017). EPA could not clearly distinguish the
relevant application methods for these NMP-based products. Due to the potential widespread industrial
and commercial use of NMP-based coating products, EPA expects that the majority of application
methods described above are relevant. Therefore, EPA assesses the following distinct occupational
exposure scenarios for this scenario:
• Spray application
• Roll or curtain application
• Dip application
• Brush or roller application
• Syringe or bead application
2.7.2 Exposure Assessment
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2.7.2.1 Worker Activities
Workers are potentially exposed to NMP in paint, coating, adhesive, and sealant formulations during
quality testing of formulations, transferring the formulations into application equipment, applying the
formulation to a substrate, and maintenance and cleaning activities (Meier et at.. 20! 3; OKJi ,
NICNAS. 2001). These activities are all potential sources of worker exposure through dermal contact,
vapor-through-skin, and inhalation of NMP vapors or paint, coating, adhesive, and sealant mists
containing NMP. Workers have further potentially inhalation exposure to NMP vapors during curing or
drying of solvent-borne formulations as the NMP evaporates from the applied formulations.
During application of paints, coatings, adhesives, and sealants, workers may manually apply the
formulation with a variety of application techniques, including spray application from a handheld spray
gun or can, brush or roller application, dipping, or syringe/bead application. All types of application are
potential exposure points for workers. However, the application of the paint, coating, adhesive, and
sealant formulations may be automated using automated spray equipment, roll/curtain equipment, or dip
application equipment. The potential for worker exposure during automated application depends on the
type of system used, specifically whether the system is open or closed. For example, automated spray
application may occur in an enclosed booth equipped with an air filtration or water curtain system to
capture overspray, limiting the potential for worker exposure (NICNAS. 2001). Alternatively, spray
application may be automated but occur in only a semi-enclosed or open space, which increases the
potential for worker exposures. The extent to which closed application systems is used in the various
industries that apply NMP-based paints, coatings, adhesives, and sealants is unknown.
The 2011 ESD on Application of Radiation Curable Coatings, Inks, and Adhesives indicates that typical
PPE may include protective clothing, gloves, safety shoes, and respiratory protection, as needed (OECD.
2011). Additional sources indicate that it is common practice for workers to wear chemical-resistant
gloves (Meier et at.. 2013; OE s09; NICNAS. 2001). The RIVM Annex XV Proposal for a
Restriction - NMP report (RIVM. ) assesses exposure scenarios that account for the use of local
exhaust ventilation (LEV) (using a 90 percent exposure reduction), gloves (using an 80 percent or a 95
percent exposure reduction), and, in some cases, a respirator with assigned protection factors (APFs) of
5 (80 percent exposure reduction) or 20 (95 percent exposure reduction).
ONUs include employees that work at the sites where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
supervisors, managers, and other employees that may be in the production areas but do not perform tasks
that result in the same level of exposures as those workers that engage in tasks related to the use of
NMP.
2.7.2.2 Number of Potentially Exposed Workers
Application of NMP-based paints, coatings, adhesives, and sealants are widespread, occurring in many
industries. EPA determined the industries likely to use NMP in paints, coatings, adhesives, and sealants
from the following sources: the non-CBI 2016 CDR results for NMP (U.S. EPA. 2016a). the 2017
market profile for NMP (AM. 2017). and the "Preliminary Information on Manufacturing, Processing,
Distribution, Use, and Disposal: NMP" document (U.S. EPA. 2017b).
In addition, EPA received public comments on the NMP risk evaluation docket indicating NMP is used
in paints, coatings, adhesives, and / or sealants in the following industries:
• Aerospace manufacturing industry (Riegle. 20.1.7')
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• Automotive manufacturing industry ("ACC. 20.1.7; Alliance of Automobile Manufacturers. 20.1.7')
• Electronics manufacturing (National Electrical Manufacturers Association., 20.1.7; Thomas. 2017)
• Semiconductor manufacturing (Fuiiftlm. 20.1.7a; Isaacs. 20.1.7)
• Construction (architectural coatings) (Davis. 20.1.7; NABTU. 20.1.7)
The industries that distinctly perform the various methods of paint, coating, adhesive, and sealant
application (e.g., spray, dip, roll) are unknown. EPA assumes that all industries may perform all
methods of application. EPA compiled the associated NAICS codes for the identified industries in Table
2-33. EPA determined the number of workers associated with each industry using Bureau of Labor
Statistics' OES data ('_ S
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Industry
Industry
Source
2016
NAICS
2016 NAICS Title
Number of
Establishment
s
Number
of
Workers
per Sitea
Number of
ONUs per
Site3
Construction
and Flooring
(Abt. 2017: U.S.
EPA. 2017b.
2016a)
238320
Painting and Wall Covering Contractors
31,943
4
0
238330
Flooring Contractors
14,601
4
0
Primary Metal
Manufacturing
(U.S. EPA
2016a)
331100
Iron and Steel Mills and Ferroalloy Manufacturing
603
53
18
331200
Steel Product Manufacturing from Purchased Steel
667
28
7
331300
Alumina and Aluminum Production and Processing
529
33 b
13 b
331400
Nonferrous Metal (except Aluminum) Production and
Processing
964
22
7
331500
Foundries
1,770
18
10
Fabricated
Metal Product
Manufacturing
(Abt. 2017: U.S.
EPA 2017b.
2016a)
332100
Forging and Stamping
2,467
10
4
332200
Cutlery and Handtool Manufacturing
1,194
7
3
332300
Architectural and Structural Metals Manufacturing
12,309
10
3
332400
Boiler, Tank, and Shipping Container Manufacturing
1,575
19
6
332500
Hardware Manufacturing
599
12
4
332600
Spring and Wire Product Manufacturing
1,196
10
3
332700
Machine Shops; Turned Product; and Screw, Nut, and Bolt
Manufacturing
23,083
2
1
332800
Coating, Engraving, Heat Treating, and Allied Activities
5,732
8
2
332900
Other Fabricated Metal Product Manufacturing
6,612
12
5
Machinery
Manufacturing
(U.S. EPA
2017b. 2016a)
333100
Agriculture, Construction, and Mining Machinery
Manufacturing
3,094
20
9
333200
Industrial Machinery Manufacturing
3,262
8
6
333300
Commercial and Service Industry Machinery Manufacturing
2,014
14
6
333400
Ventilation, Heating, Air-Conditioning, and Commercial
Refrigeration Equipment Manufacturing
1,776
31
8
333500
Metalworking Machinery Manufacturing
6,527
4
4
333600
Engine, Turbine, and Power Transmission Equipment
Manufacturing
1,073
30
17
333900
Other General Purpose Machinery Manufacturing
6,048
13
7
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Industry
Industry
Source
2016
NAICS
2016 NAICS Title
Number of
Establishment
s
Number
of
Workers
per Sitea
Number of
ONUs per
Site3
Computer and
Electronic
Product
Manufacturing
(Abt. 2017: U.S.
EPA. 2017b.
2016a)
334100
Computer and Peripheral Equipment Manufacturing
1,091
12 b
12 b
334200
Communications Equipment Manufacturing
1,369
13
14
334300
Audio and Video Equipment Manufacturing
486
6 b
6 b
334400
Semiconductor and Other Electronic Component
Manufacturing
3,979
30
27
334500
Navigational, Measuring, Electromedical, and Control
Instruments Manufacturing
5,231
17
18
334600
Manufacturing and Reproducing Magnetic and Optical Media
521
6 b
6 b
Electrical
Equipment,
Appliance, and
Component
Manufacturing
(U.S. EPA
2016a)
335100
Electric Lighting Equipment Manufacturing
1,104
17
5
335200
Household Appliance Manufacturing
303
102
20
335300
Electrical Equipment Manufacturing
2,124
28
12
335900
Other Electrical Equipment and Component Manufacturing
2,140
23
8
Transportation
Equipment
Manufacturing
(Abt. 2017: U.S.
EPA 2017b.
2016a)
336100
Motor Vehicle Manufacturing
340
235 b
99 b
336200
Motor Vehicle Body and Trailer Manufacturing
1,917
41
7
336300
Motor Vehicle Parts Manufacturing
5,088
51
15
336400
Aerospace Product and Parts Manufacturing
1,811
75
64
336500
Railroad Rolling Stock Manufacturing
243
35
15
336600
Ship and Boat Building
1,541
36
13
Wholesale and
Retail Trade
(U.S. EPA
2016a)
424690
Other Chemical and Allied Products Merchant Wholesalers
9,517
1
0
Total establishments and number of potentially exposed workers and ONUs =c
170,000
2,000,000
910,000
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest whole number.
b - No 2016 BLS data was available for this NAICS. Number of relevant workers per site and ONUs per site within this NAICS were calculated using the ratios of
relevant workers and ONUs to the number of total employees at the 3-digit NAICS level.
c - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two significant figures.
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2.7.2.3 Occupational Exposure Assessment Methodology
2.7.2.3.1 Inhalation
Appendix A.7 summarizes the inhalation monitoring data for NMP-based paint, coating, adhesive, and
sealant application that EPA compiled from published literature sources, including 8-hour TWA, short-
term, and partial shift sampling results. EPA also compile modeled exposure data in this appendix.
Where available for the various types of application, EPA used monitoring data or surrogate monitoring
data for the use of NMP during Cleaning that had the highest quality rating to assess exposure. Where
monitoring data was unavailable for an application type, EPA used modeling estimates with the highest
data quality to assess exposure. This is further described below and in Appendix A.7.
EPA used monitoring data presented in Appendix A.7 to determine the PBPK model inputs for
inhalation exposures during spray application. EPA did not find inhalation monitoring data on roll
coating with NMP-containing formulations, thus used data from EPA OPPT's t IV Roll Coating Model
in conjunction with NMP concentration data to determine inputs to the PBPK model for roll coating in
this scenario. The EPA OPPT UV Roll Coating Model involved deterministic modeling. EPA found
limited data on the dip application of paints, coatings, adhesives, and sealants, thus EPA used data for
dip cleaning with NMP from the Cleaning scenario (refer to Section 2.10) as surrogate (surrogate work
activities using NMP) for this scenario. EPA used a modeled exposure for the brush application of a
substance containing NMP that was presented in the RIVM Annex XV Proposal for a Restriction - NMP
report. The personal breathing zone monitoring data and the modeled exposures are summarized in
Table 2-34. The area monitoring data are summarized in Table 2-35. EPA cannot distinguish ONU
exposures from worker exposures from the data in Table 2-34 and Table 2-35. EPA used the data in
Table 2-34 for inhalation exposure inputs to the PBPK model, as described in Section 2.7.3.
Table 2-34. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Application of Paints, Coatings, Adhesives, and Sealants
Full-Shift NMP
Duration-Based
Work
Activity
Parameter
Characterization
Air
NMP Air
Data
Concentration
Concentration
Source
Quality
(mg/m3, 8-hour
TWA)
(mg/m3)
Rating
Low-end (of
0.04 (duration =
range)
0.04
4 hr)
Spray
Application
Mean
0.53
0.53 (duration =
4 hr)
(NIOSH. 1998)
High
High-end (of
4.51 (duration =
range)
4.51
4 hr)
Roll / Curtain
Central tendency
(50th percentile)
0.03
No data
EPA OPPT UV Roll
Not
Application
High-end (95th
percentile)
0.19
No data
Coating Model
applicable3
Dip
Application
Central tendency
(50th percentile)
0.99
No data
Surrogate data
(surrogate work
activities using NMP)
Medium to
high
High-end (95th
percentile)
2.75
No data
from: (RIVM. 2013:
IFA. 2010: Nishimura
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et al.. 2009; Bader et
al.. 2006; Xiaofei et
al.. 2000)
Roller / Brush
and Syringe /
Bead
Application
Single estimate
4.13
No data
(RIVM. 2013)
High
a - EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically review models
that were developed by EPA.
Table 2-35. Summary of Occupational Non-User Inhalation Exposure During Application of
Paints, Coatings, Adhesives, and Sealants
Work Activity
Parameter
Characterization
Full-Shift NMP
Air Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Spray Application
Low-end
0.04
0.04 (duration = 4
hr)
(NIOSH.
1998)
High
Mean
0.14
0.14 (duration = 4
hr)
High-end
0.53
0.53 (duration = 4
hr)
Roll / Curtain
Application
No data
No data
No data
No data
Not
applicable
No data
No data
No data
No data
Not
applicable
Dip Application
No data
No data
No data
No data
Not
applicable
No data
No data
No data
No data
Not
applicable
Roller / Brush and
Syringe / Bead
Application
No data
No data
No data
No data
Not
applicable
2.7.2.3.2 Dermal
Table 2-36 summarizes the parameters used to assess dermal exposure during application of paints,
coatings, adhesives, and sealants containing NMP. EPA assesses dermal exposure to NMP at the
specified liquid weight fraction, skin surface area, and exposure duration, based on the methodology
described below.
NMP Weight Fraction
EPA gathered paint, coating, adhesive, and sealant product concentration from a variety of sources,
including 2017 market profile for NMP (Abt. 2017). the "Preliminary Information on Manufacturing,
Processing, Distribution, Use, and Disposal: NMP" document (U.S. EPA 2017b). public comments to
the NMP risk evaluation docket, and published literature (U.S. EPA. 2017b; RIVM. 2013; Muenter and
Blach. 2010; NICNAS. 2001. 1998). The overall confidence rating of the data from these sources range
from medium to high.
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EPA identified multiple paint, coating, adhesive, and sealant products containing NMP. Note that some
data points are not for one specific product but are estimated ranges of the expected NMP concentration
in paints, coatings, adhesives, and sealants. Where NMP concentration was provided in a range, EPA
used the midpoint of the range for the calculations of typical and worst-case NMP concentration
described below. NMP concentrations in paints, coatings, adhesives, and sealants range from 0.06
weight percent NMP up to 90 weight percent NMP. With these data, EPA determined a typical and
worst-case estimate of NMP concentration in these products, calculated as the 50th percentile and 95th
percentile, respectively. Based on these data, the typical NMP concentration is 2 weight percent and the
worst-case NMP concentration is 53.4 weight percent.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. Due to the wide-spread commercial and industrial use of NMP-based paints, coatings, adhesives,
and sealants, EPA assumes that no gloves are used for the high-end exposure scenario, corresponding to
a protection factor of 1 from Table 1-2 of Section 1.4.3.2.3. EPA expects that workers may potentially
wear gloves but does not know the likelihood that workers wear gloves of the proper material and have
training on the proper usage of gloves. Some sources indicate that workers wear chemical-resistant
gloves (Meier et al.. 2013; OECD. 2009; NICNAS. 20011 while others indicate that workers likely wear
gloves that provide a lower protection factor (RIVM. 2013). No information on employee training was
found. Based on this information and the widespread use of NMP in this scenario, EPA assesses a
central tendency scenario assuming the use of gloves with minimal to no employee training,
corresponding to a protection factor of 5 from Table 1-2 of Section 1.4.3.2.3. EPA did not find data on
the use of gloves for this occupational exposure scenario and the glove protection factor assumptions are
based on professional judgment. The assumed glove protection factor values are highly uncertain.
Exposure Duration
EPA found inhalation monitoring data for spray application indicating an exposure duration of four
hours. EPA did not find additional data on exposure duration. As described in Section 1.4.3.2.4, EPA
assumes a high-end exposure duration of eight hours and a central tendency exposure duration of four
hours.
Table 2-36. Summary of Parameters for Worker Dermal Exposure to Liquids During Application
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
All forms of
application
listed above
Central Tendency
5
0.02
445 (f)
535 (m)
4
74 (f)
88 (m)
High-End
1
0.534
890 (f)
1,070 (m)
8
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.7.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-37.
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The numeric parameters corresponding to the characterizations presented in Table 2-37 are summarized
in Table 2-38. These are the inputs used in the PBPK model.
Table 2-37. Characterization of PBPK Model Input Parameters for Application of Paints,
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Ch ar acteriz ation
Central
Tendency
Spray
application
Mean
Based on 4-
hour TWA
data
1-hand
Yes
Central Tendency
High-end
Spray
application
High-end (of range)
Based on 8-
hour TWA
data
2-hand
No
High-end
Central
Tendency
Roll/
curtain
application
Central tendency
(50th percentile)
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Roll/
curtain
application
High-end (95th
percentile)
Based on 8-
hour TWA
data
2-hand
No
High-end
Central
Tendency
Dip
application
Central tendency
(50th percentile)
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Dip
application
High-end (95th
percentile)
Based on 8-
hour TWA
data
2-hand
No
High-end
Central
Tendency
Brush
application
Single estimate
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Brush
application
Single estimate
Based on 8-
hour TWA
data
2-hand
No
High-end
Table 2-38. PBPK Model Input Parameters for Application of Paints, Coatings, Adhesives, and
Sealants
Scenario
Activity
Duration-
Based NMP
Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2)a b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
Spray
application
0.53
4
445 (f)
535 (m)
5
0.02
74 (f)
88 (m)
High-end
Spray
application
4.51
8
890 (f)
1,070 (m)
1
0.534
74 (f)
88 (m)
Central Tendency
Roll/
curtain
application
0.06
4
445 (f)
535 (m)
5
0.02
74 (f)
88 (m)
High-end
Roll/
curtain
application
0.19
8
890 (f)
1,070 (m)
1
0.534
74 (f)
88 (m)
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Scenario
Activity
Duration-
Based NMP
Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
Dip
application
1.98
4
445 (f)
535 (m)
5
0.02
74 (f)
88 (m)
High-end
Dip
application
2.75
8
890 (f)
1,070 (m)
1
0.534
74 (f)
88 (m)
Central Tendency
Brush
application
8.26
4
445 (f)
535 (m)
5
0.02
74 (f)
88 (m)
High-end
Brush
application
4.13
8
890 (f)
1,070 (m)
1
0.534
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.7.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.8 Electronic Parts Manufacturing
2.8.1 Process Description
Within the electronics industries, NMP serves multiple functions, including:
• As a binder solvent in the assembly of lithium-ion batteries (Mitsubishi Chemical 2017;
Argonne National Laboratory. 2015; RIVM. 2013)
• Solvent for the cleaning of electronic parts, including semiconductor wafer cleaning (Isaacs.
2017; NIH. 2017; RIVM. 2013; U.S. EPA 1998)
• Component of various formulations, including photoresists, polyimides, anti-reflective coatings,
and insulative coatings (Isaacs. 2017; Thomas. 2017; RIVM. 2013)
• Additive to coatings for magnet wires that are used in the manufacturing of motors, generators,
and transformers (RIVM. 2013)
• Component of photoresist stripper formulations (Isaacs. 2017; RIVM. 2013)
• Component of solder mask remover formulations for printed circuit boards (Roberts. 2017)
NMP is used as a solvent in lithium battery manufacturing (Mitsubishi Chemical. 2017). Specifically,
NMP is used as a carrier for binder resins used to adhere electrolytic cells to the battery (Roberts. 2017;
Argonne National Laboratory. 2015; RIVM. 2013). In a public comment submitted to the EPA NMP
risk evaluation docket, one company indicated that NMP is first mixed with powder chemicals, binders,
and other substrates, then the solution is coated onto thin metal foils with a precise automated roll
coating process (Roberts. 2017). EPA found information that NMP may also be used as an additive in
electrolytes and in coatings used on the outside of batteries (RIVM. 2013).
NMP is used for the cleaning and stripping of silicon wafers to prepare the wafer surfaces for
application of photoresist and other coating formulations (Mitsubishi Chemical. 2017; NIH. 2017;
RIVM. 2013). NMP may be used to clean other electronic parts (U.S. EPA. 1998). NMP also functions
as an ingredient for wafer coatings, including polyimides and anti-reflective coatings (RIVM. 2013).
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NMP may be used as a thinner in photoresist formulations (Mitsubishi Chemical. 2017) and as a carrier
for other coatings (U.S. EPA. 1998). A public comment to the NMP risk evaluation docket from Elantas
Electrical Insulation indicates NMP is present in residual quantities in electrical insulating films
(Thomas. 2017). EPA did not find additional information on the cleaning of electronic parts or the
applications of the described coatings but expects that the processes occur under well-controlled
conditions, as is customary for the electronics industry.
NMP is also used in coatings for magnet wires (RIVM. 2013). Specifically, NMP is an additive in
polymeric coatings that are used to coat magnet wires, often to give them thermal and solvent resistance.
The coating containing NMP is applied to the magnet wires by dipping, rolling, or pouring the coating
onto the wires, which are then heated, thereby allowing the coating to cure onto the wire. NMP is
evaporated from the coating during the curing process such that it is not likely present in the final coated
magnet wires. The RIVM Annex XVProposal for a Restriction - NMP report (RIVM. 2013) indicates
that NMP is used particularly for magnet wires that require high quality coatings or coatings that are
cured at relatively high temperatures. The magnet wires are used in the manufacturing of products such
as motors, generators, and transformers.
NMP is used to strip photoresist resins from wafer surfaces (Roberts. _ * \_ 8). The NMP
Producers Group, Inc. provided information on the photoresist stripping process, stating that the process
can be batch or continuous and is controlled within a closed system equipped with exhaust ventilation
(Roberts. 2017). NMP is used at up to 100 percent concentration and is heated up to 85°F for use in the
stripping process. During stripping, the NMP solution dissolves any photoresist remaining on the
surfaces of the wafers after developing and etching (OECD. 2010b). Waste NMP containing the
photoresist that was removed from the wafers is either treated on-site or disposed off-site as hazardous
waste (Roberts. ).
The NMP Producers Group, Inc. also indicated that NMP is used to remove solder mask from circuit
boards (Roberts. 2017). NMP is used at up to 99.9 percent purity in an open-topped tank equipped with
ventilation. The NMP can either be used at ambient temperature or heated up to 180°F. Waste NMP
containing the removed solder mask is either treated on-site or disposed off-site as hazardous waste.
EPA did not find exposure data to differentiate the processes described above. EPA collectively refers to
these operations as electronic parts manufacturing in the remainder of this section.
2.8.2 Exposure Assessment
2.8.2.1 Worker Activities
During this scenario, workers are potentially exposed while unloading NMP from containers and
charging it into equipment. If containers are not manually unloaded by workers, workers may still be
potentially exposed when connecting and disconnecting transfer hoses between the containers and
equipment. Workers may also be potentially exposed during dilution, mixing, or sampling of solutions
containing NMP, if these processes occur (Saft, 2017b; RIVM. 2013). All these activities are potential
sources of worker exposure through dermal contact, vapor-through-skin, and inhalation of NMP vapors.
As described in Section 2.8, NMP may be used at elevated temperatures, which may increase the
generation of NMP vapors and potential worker inhalation exposures. However, the processes in which
heated NMP is used, as well as many other processes within the electronics industries, are frequently
totally or partially enclosed and equipped with ventilation that reduces the potential for worker
exposures (Saft, 2017b; Isaacs. 2017; Roberts. 2017; RIVM. 2013).
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A battery manufacturing company that submitted a public comment to the NMP risk evaluation docket
indicated that workers use face shields, gloves, and chemical resistant clothing (Saft. 2017b). The NMP
Producers Group, Inc. also indicated in a public comment that worker exposures in the electronics
industries are controlled through the use of the appropriate PPE (Roberts. 2017).
The 2010 ESD on the Use of Photoresist in Semiconductor Manufacturing and a public comment from
the Semiconductor Industry Association (SIA) indicate that workers in the semiconductor manufacturing
industry are typically required to wear full-body chemical-resistant clothing with face shields, chemical-
resistant gloves, goggles, and respirators, as needed, inside production areas, including the areas where
photoresist supply containers and waste disposal lines are connected to the equipment (Isaacs. 2017;
OECD. 2010b).
ONUs include employees that work at the sites where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
supervisors, managers, and other employees that may be in the production areas but do not perform tasks
that result in the same level of exposures as those workers that engage in tasks related to the use of
NMP.
2.8.2.2 Number of Potentially Exposed Workers
Based on the processes described in Section 2.8, NMP is used primarily in the computer and electronic
product manufacturing sector, which are included in NAICS codes starting with 334, and the electrical
equipment, appliance, and component manufacturing sector, which are included in NAICS codes
starting with 335. In addition to these NAICS codes, EPA expects that NMP may be used in similar
capacities within other electronics manufacturing industries. A public comment submitted to the NMP
risk evaluation docket from the Aerospace Industries Association (AIA) indicates NMP is used for
electronics manufacturing for the aerospace industry (Riegle. 2017). EPA compiled the identified
NAICS codes for these industries in Table 2-39. The number of workers associated with each industry
were identified using Bureau of Labor Statistics' OES data (U.S. BLS. 2016) and the U.S. Census'
SUSB (U.S. Census Bureau. 2015). The number of establishments within each industry that use NMP
and the number of employees within an establishment exposed to NMP are unknown. Therefore, EPA
provides the total number of establishments and employees in these industries as bounding estimates of
the number of establishments that use and the number of employees that are potentially exposed to NMP
in electronics manufacturing. These bounding estimates are likely overestimates of the actual number of
establishments and employees potentially exposed to NMP in the electronics manufacturing industries.
Table 2-39. US Number of Establishments and Employees for Electronic Parts Manufacturing
Number
of
Worker
s Site8
Numbe
2016
Number of
r of
Industry
NAIC
S
2016 NAICS Title
Establishment
s
ONUs
per
Site8
Computer and
Electronic
3341
Computer and Peripheral Equipment
Manufacturing
1,091
12 b
12
Product
3342
Communications Equipment Manufacturing
1,369
13
14
3343
Audio and Video Equipment Manufacturing
486
6 b
6
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Number
of
Worker
s Site3
Numbe
2016
Number of
r of
Industry
NAIC
S
2016 NAICS Title
Establishment
s
ONUs
per
Site8
Manufacturin
3344
Semiconductor and Other Electronic
3,979
30
27
g
Component Manufacturing
3345
Navigational, Measuring, Electromedical, and
Control Instruments Manufacturing
5,231
17
18
3356
Manufacturing and Reproducing Magnetic
and Optical Media
521
6 b
6
Electrical
3351
Electric Lighting Equipment Manufacturing
1,104
17
5
Equipment,
3352
Household Appliance Manufacturing
303
102
20
Appliance,
3353
Electrical Equipment Manufacturing
2,124
28
12
and
Component
Manufacturin
g
3359
Other Electrical Equipment and Component
Manufacturing
2,140
23
8
Other
3364
Aerospace Product and Parts Manufacturing
1,811
75
64
Miscellaneous
Technologies
3391
Medical Equipment and Supplies
Manufacturing
10,767
11
4
Total number of establishments, workers, and ONUs potentially
exposedc
31,000
660,000
450,000
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest whole number.
b - No 2016 BLS data was available for this NAICS. Number of relevant workers per site and ONUs per site within this
NAICS were calculated using the ratios of relevant workers and ONUs to the number of total employees at the 3-digit
NAICS level.
c - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.8.2.3 Occupational Exposure Assessment Methodology
2.8.2.3.1 Inhalation
Appendix A.8 summarizes the inhalation monitoring data for use of NMP in the electronics
manufacturing industry. As previously indicated, electronic parts manufacturing in this scenario covers
the use of NMP for battery manufacturing, cleaning of electronic parts, coating of electronic parts,
including magnet wire coatings, and photoresist and solder mask stripping.
However, EPA only found inhalation monitoring data for the use of NMP in semiconductor
manufacturing. Specifically, EPA uses data received from the European Semiconductor Industry
Association (SIA), which include full-shift personal breathing zone sampling results at semiconductor
fabrication facilities during container handling of both small containers and drums, workers inside the
fabrication rooms, maintenance workers, workers that unload trucks containing virgin NMP (100%), and
workers that load trucks with waste NMP (92%) (SIA 2019a). While operations for the various types of
electronics manufacturing that are included in this scenario may vary, EPA expects these data from SIA
are representative of the operating conditions expected at electronic parts manufacturing facilities, due to
the use of similarly controlled operations.
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The available monitoring data was summarized into the PBPK modeling full-shift input parameters in
Table 2-40. The majority (96% of all samples) of samples in SIA were non-detect for NMP (SIA
2019a). Because the geometric standard deviation of the data set is greater than three, EPA used the
limit of detection (LOD) divided by two to calculate central tendency and high-end values where
samples were non-detect for NMP (EPA 1994). Due to the high amount of non-detect results, this
method may result in bias. This is further described in Appendix A.8. The SIA data included samples of
both 8-hour TWA and 12-hour TWA values, with the majority of the data being 12-hour TWA. EPA
used the 12-hour TWA values to assess occupational exposures in this scenario, as there is more data
available for this exposure duration, indicating that typical shifts in this industry are 12 hours. Note,
however, that the single data points available for the last two tasks in Table 2-40 are 8-hour TWA
values.
These data also include area monitoring data in the fabrication area, which are summarized in Table
2-41. EPA cannot distinguish ONU exposures from worker exposures from the data in Table 2-40 and
Table 2-41. EPA used the data in Table 2-40 for inhalation exposure inputs to the PBPK model, as
described in Section 2.8.3.
Table 2-40. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Elecl
ronic Parts Manufacturing
Work Activity a
Parameter
Characterization
Full-Shift NMP
Air Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3,12-hour
TWA)
(mg/m3)
Container
handling, small
containers
Central tendency
(50th percentile)
0.507
No data
(SIA.
2019a)
High
High-end (95th
percentile)
0.608
No data
Container
handling, drums
Central tendency
(50th percentile)
0.013
No data
High-end (95th
percentile)
1.54
No data
Fab worker
Central tendency
(50th percentile)
0.138
No data
High-end (95th
percentile)
0.405
No data
Maintenance
Central tendency
(50th percentile)
0.020
No data
High-end (95th
percentile)
0.690
No data
Virgin NMP truck
unloading
Single value
4.78 b
No data
Waste truck
loading
Single value
0.709 b
No data
a - Electronic parts manufacturing includes the use of NMP for battery manufacturing, cleaning of electronic parts, coating of
electronic parts, including magnet wire coatings, and photoresist and solder mask stripping,
b - These are 8-hour TWA values.
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Table 2-41. Summary of Area Monitoring During Electronic Parts Manufacturing
Work
Activity a
Parameter
Characterization
NMP Exposure
Duration-Based NMP
Data
Concentration
Air Concentration
Source
Quality
(mg/m3, 8-hr TWA)
(mg/m3)
Rating
Fab area
Central tendency
0.162
No data
(SIA.
High
High-end
0.284
No data
2019a)
a - Electronic parts manufacturing includes the use of NMP for battery manufacturing, cleaning of electronic parts, coating of
electronic parts, including magnet wire coatings, and photoresist and solder mask stripping.
2.8.2.3.2 Dermal
Table 2-42 summarizes the parameters used to assess dermal exposure during use of NMP in the
electronics industries. EPA assumed that the skin was exposed dermally to NMP at the specified liquid
weight fraction, skin surface area, and exposure duration.
NMP Weight Fraction
The SIA monitoring data included some NMP concentration data for the products associated with the
inhalation monitoring samples. These data have an overall confidence rating of high. Where this data
was available, EPA calculated the 50th percentile and 95th percentile NMP concentration for use as the
central tendency and high-end NMP concentrations, on a per task basis. Where the SIA data did not
include NMP concentrations data, EPA used NMP concentrations determined from literature as
described below. These concentrations are summarized in Table 2-42.
EPA identified multiple products and sources containing data on the concentration of NMP used in the
electronics industry. The 2017 market profile on NMP and the "Preliminary Information on
Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document identified electronics
products with NMP concentrations ranging from less than one up to 100 weight percent NMP (Abt.
2017; U.S. EPA 2017b). The NMP Producers Group, Inc. submitted a public comment to the NMP risk
evaluation docket that indicates NMP is used up to 100 percent purity in photoresist removers and up to
99.9 percent purity in a remover solution for solder mask from printed circuit boards (Roberts. 2017).
These data have an overall confidence rating of high. Based on this information, EPA calculated typical
(50th percentile) and worst-case (95th percentile) weight percent of NMP to be 15and 99.9, respectively.
Note that, where NMP concentration was provided in a range, EPA used the midpoint of the range for
the calculations of typical and worst-case NMP concentration.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. The PPE information described in Section 2.8.2.1 indicates that workers in these industries are
likely to wear gloves. This information indicates workers likely wear chemical-resistant gloves (Isaacs.
2017; OECD. 2010b). In addition, due to the highly controlled nature of certain electronics
manufacturing operations, EPA expects employees to have at least basic training on glove usage. Thus,
EPA assesses a protection factor of 10 from Table 1-2 of Section 1.4.3.2.3 for both the central tendency
and high-end scenarios for this scenario. EPA did not find data on the use of gloves for this occupational
exposure scenario and the glove protection factor assumptions are based on professional judgment. The
assumed glove protection factor values are highly uncertain.
Exposure Duration
EPA did not find data on exposure duration. As described in Section 1.4.3.2.4, EPA uses the maximum
shift duration for the high-end and the mid-point of the shift duration for the central tendency. As
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described in the previous section, the container handling, fab worker, and maintenance tasks are
performed by workers on a 12-hour shift. The high-end and central tendency for these tasks are 12 hours
and 6 hours, respectively. The virgin NMP truck unloading and waste NMP truck loading tasks are
performed by workers on a 8-hour shift. The high-end and central tendency for these tasks are 8 hours
and 4 hours, respectively.
Table 2-42. Summary of Parameters for Worker Dermal Exposure During Electronic Parts
Manufacturing
Work Activity a
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed b
Exposure
Duration
Body
Weight b
Unitless
cm2
hr/day
kg
Container
handling, small
containers
Central Tendency
10
0.6
445 (f)
535 (m)
6
74 (f)
High-End
10
0.75
890 (f)
1,070 (m)
12
88 (m)
Container
Central Tendency
10
0.5
445 (f)
535 (m)
6
74 (f)
handling, drums
High-End
10
0.75
890 (f)
1,070 (m)
12
88 (m)
Fab worker
Central Tendency
10
0.15
445 (f)
535 (m)
6
74 (f)
High-End
10
0.999
890 (f)
1,070 (m)
12
88 (m)
Maintenance
Central Tendency
10
0.55
445 (f)
535 (m)
6
74 (f)
High-End
10
1
890 (f)
1,070 (m)
12
88 (m)
Virgin NMP
Central Tendency
10
1
445 (f)
535 (m)
4
74 (f)
truck unloading
High-End
10
1
890 (f)
1,070 (m)
8
88 (m)
Waste truck
Central Tendency
10
0.92
445 (f)
535 (m)
4
74 (f)
loading
High-End
10
0.92
890 (f)
1,070 (m)
8
88 (m)
a Electronic parts manufacturing includes the use of NMP for battery manufacturing, cleaning of electronic parts, coating of
electronic parts, including magnet wire coatings, and photoresist and solder mask stripping.
b EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.8.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-43.
The numeric parameters corresponding to the characterizations presented in Table 2-43 are summarized
in Table 2-44. These are the inputs used in the PBPK model.
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Table 2-43. Characterization of PBPK Model Input Parameters for Electronic Parts
i Manufacturing
Scenario
Work
Activity a
Air Concentration
Data
Characterization b
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Ch ar acteriz ation
Central
Tendency
All
activities
Central tendency (50th
percentile)
Mid-point
of shift
duration
1-hand
Yes
Central tendency
High-end
All
activities
High-end (95th
percentile)
High-end of
shift
duration
2-hand
Yes
High-end
a Electronic parts manufacturing includes the use of NMP for battery manufacturing, cleaning of electronic parts, coating of
electronic parts, including magnet wire coatings, and photoresist and solder mask stripping.
b Only a single estimate was available for virgin NMP truck unloading and waste truck loading. This single air concentration
value was used with both central tendency and high-end duration and dermal parameters.
Table 2-44. PBPK Model Input Parameters for Electronic Parts Manufacturing
Duration-Based
NMP Air
Concentration
(mg/m3)
Skin
Activity
Scenario
Exposure
Duration
(hr)
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weigh
t (kg)a
Container
handling,
Central
tendency
N/A
6
445 (f)
535 (m)
10
0.6
74 (f)
88 (m)
small
containers
High-end
N/A
12
890 (f)
1,070 (m)
10
0.75
74 (f)
88 (m)
Container
handling,
drums
Central
tendency
N/A
6
445 (f)
535 (m)
10
0.5
74 (f)
88 (m)
High-end
N/A
12
890 (f)
1,070 (m)
10
0.75
74 (f)
88 (m)
Fab Worker
Central
tendency
N/A
6
445 (f)
535 (m)
10
0.15
74 (f)
88 (m)
High-end
N/A
12
890 (f)
1,070 (m)
10
0.999
74 (f)
88 (m)
Maintenanc
Central
tendency
N/A
6
445 (f)
535 (m)
10
0.55
74 (f)
88 (m)
e
High-end
N/A
12
890 (f)
1,070 (m)
10
1
74 (f)
88 (m)
Virgin NMP
truck
Inhalation -
Single value;
Dermal -
Central
tendency
N/A
4
445 (f)
535 (m)
10
1
74 (f)
88 (m)
unloading
Inhalation -
Single value;
Dermal -
High-end
N/A
8
890 (f)
1,070 (m)
10
1
74 (f)
88 (m)
Waste truck
loading
Inhalation -
Single value;
Dermal -
N/A
4
445 (f)
535 (m)
10
0.92
74 (f)
88 (m)
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Activity
Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weigh
t (kg)a
Central
tendency
Inhalation -
Single value;
Dermal -
High-end
N/A
8
890 (f)
1,070 (m)
10
0.92
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.8.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.9 Printing and Writing
2.9.1 Process Description
There are multiple types of printing technologies, including lithography, rotogravure, flexography,
screen, letterpress, and digital, which encompasses electrophotography and inkjet printing. Facilities
tend to employ one type of printing process exclusively, although some of the larger facilities may use
two or more types. Solvents are used in inks as carriers for colorants and allow the colorants to bind to
the substrate after drying (OECD. 2010c). Solvents also modify the viscosity of the inks, allowing them
to be more easily applied to substrates. Hawley's Condensed Chemical Dictionary indicates that NMP
specifically can be used as a pigment dispersant in printing formulations (Larranaga et al.. 2016).
The "Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document and a public comment submitted to the NMP risk evaluation docket identify three inks,
ranging from one to 10 weight percent NMP, that are used in inkjet printing (Gerber. 2017; U.S. EPA
2017b). The "Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal:
NMP" document and 2017 market profile for NMP identify two additional ink products that are both
less than five weight percent NMP and have unspecified printing application methods (Abt 2017: U.S.
EPA 2017b). The "Preliminary Information on Manufacturing, Processing, Distribution, Use, and
Disposal: NMP" document additionally states that NMP is expected to be used in lithography and screen
printing but did not identify products that specify this type of printing method (U.S. EPA 2017b).
The fundamental steps in printing are referred to as imaging/film processing, image carrier preparation,
printing, and post-press operations. Printing processes also include cleanup operations, that may occur
continuously during the print run or between runs. The 2010 Draft Scoping Document for an ESD on the
Manufacture and Use of Printing Inks provides information on the various types of printing processes
(OECD. 2010c).
During lithography, an image is transferred from a plate onto paper or another substrate. The image area
on printing plates is treated to absorb an oil-based ink in the image areas and to absorb only water in the
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non-image areas (OECD. 2010c). At the printing facility, ink is loaded into the printing machine and
transferred from the plate to the ink rollers and ultimately onto the paper. Depending on the final printed
product, additional roller units may be used to add various colors and layers to the printed image.
During screen printing, an image is transferred to a substrate through a porous mesh (OECD. 2010c).
The mesh is stretched over a frame and a stencil is applied to the mesh to define the image. Ink is
applied to the mesh and pressure is applied to the ink to force it through the mesh and onto the substrate.
Inkjet printing is the most common method used in digital printing (OECD. 2010c). A digital image is
created on a computer and then transferred onto the substrate with a digital printing press. Small drops
of ink are applied to the substrate from a printing press nozzle by first passing the ink drops through an
electrostatic field and then deflecting the charged drops from a oppositely charge printing plate onto the
substrate. Several types of inks can be used for digital printing, including solid ink, wet/dry toner
systems, and liquid ink.
The "Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document and 2017 market profile for NMP additionally identify one commercial and consumer product
in which NMP is used in the ink within a marker at 10 to 20 weight percent NMP (Abt > . I ^ ^ \
2017b). The safety datasheet (SDS) for this product lists the product use as "weather-resistant marker for
polyurethane tags" (http://www.markal.eom/assets/l/7/aw plastic eartag white medtip.pdf).
2.9.2 Exposure Assessment
2.9.2.1 Worker Activities
Workers are potentially exposed to NMP during multiple activities involved in printing operations,
including unloading volatile inks, transferring inks into printing equipment, operating the printing
process, and subsequent cleaning and maintenance activities. These activities are potential sources of
worker exposure through dermal contact, vapor-through-skin, and inhalation of NMP mists and vapors.
EPA did not identify information on the use of engineering controls and worker PPE in the printing
industry. NIOSH conducted a health hazard evaluation (HHE) at a newspaper printing facility and found
that workers may wear hearing protection and gloves, but do not always do so (Belanger and Cove.
1983).
ONUs include employees that work at the sites where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
supervisors, managers, and other employees that may be in the printing areas but do not perform tasks
that result in the same level of exposures as those workers that engage in tasks related to the use of
NMP.
2.9.2.2 Number of Potentially Exposed Workers
This section identifies worker population estimates for use of NMP-based printing inks. Application of
these products are expected to fall within the NAICS group 323, Printing and Related Support
Activities. EPA compiled the 6-digit NAICS codes for each industry within this group in Table 2-45.
NAICS 323111, Commercial Printing (except Screen and Books), captures businesses that perform
lithographic, gravure, flexographic, letterpress, engraving, and digital printing. NAICS 323113,
Commercial Screen Printing, capture screen printing activities. NAICS 323117 and 323120 capture
printing of books and support activities for printing, respectively. As discussed in Section 2.10, EPA
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identified one marker containing NMP, which is a commercial and consumer product. EPA does not
know if this marker is specifically used in certain industries and does not have a way of estimating the
number of commercial workers that use and are potentially exposed to these markers.
The number of workers associated with each identified industry using Bureau of Labor Statistics' OES
data (U.S. BLS. 2016) and the U.S. Census' SUSB (U.S. Census Bureau. 2015). The number of
establishments within each industry that use NMP-based printing inks and the number of employees
within an establishment exposed to these NMP-based products are unknown. Therefore, EPA provides
the total number of establishments and employees in these industries as bounding estimates of the
number of establishments that use and the number of employees that are potentially exposed to NMP-
based printing inks. These bounding estimates are likely overestimates of the actual number of
establishments and employees potentially exposed to NMP during printing activities.
Table 2-45. US Number of Establishments and
Employees for Printing and Writing
Number of
Establishments
Number of
Number of
2016 NAICS
2016 NAICS Title
Workers
ONUs per
per Sitea
Site8
323111
Commercial Printing (except Screen and
Books)
18,687
2
1
323113
Commercial Screen Printing
4,956
1
1
323117
Books Printing
447
6
3
323120
Support Activities for Printing
1,598
2
1
Total establishments and number of potentially exposed
workers and ONUs = b
26,000
53,000
25,000
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest whole number.
b - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.9.2.3 Occupational Exposure Assessment Methodology
2.9.2.3.1 Inhalation
Appendix A.9 summarizes methodology for determining potential worker inhalation exposure
concentrations. EPA did not find personal breathing zone monitoring data for the use of NMP-based
printing inks. As surrogate for personal breathing zone monitoring data for printing activities, EPA used
ink mist concentration data from a NIOSH Health Hazard Evaluation at a newspaper printing shop, with
assumed NMP concentrations, to assess potential inhalation exposures in this scenario (Belanger and
Cove. 1983). Of the available data, this surrogate data has the highest quality; thus, EPA uses this data to
assess exposure for this use.
In addition, EPA did not find inhalation monitoring data for the use of writing utensils containing NMP.
EPA does not assess potential inhalation exposures during the use of NMP-based writing inks based on
information indicating these exposures may be negligible from a NICNAS assessment (Australian
Government Department of Health. 2016) and the likely outdoor use of the one writing product that was
identified (weather-resistant marker). See Appendix A.9 for additional rationale.
The monitoring data presented in Table 2-46 are the input parameters used for the PBPK modeling. EPA
compiled 4-hour exposure concentration data that can be correlated to the associated dermal exposure
durations in Table 2-47.
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Table 2-46. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Printing ant
Writing
Full-Shift NMP Air
Duration-Based
NMP Air
Concentration
Data
Quality
Work
Activity
Parameter
Characterization
Concentration
Source
(mg/m3, 8-hour
TWA)
(mg/m3)
Rating
Central tendency (50th
0.018
0.016 (duration = 4
Printing
percentile)
hr)
(Belanser and
Medium
High-end (95th
0.172
0.042 (duration = 4
Cove. 1983)
percentile)
hr)
Writing
Not assessed
2.9.2.3.2 Dermal
Table 2-47 summarizes the parameters used to assess dermal exposure during printing and writing
activities. EPA assesses dermal exposure to NMP at the specified liquid weight fraction, skin surface
area, and exposure duration, based on the methodology described below.
NMP Weight Fraction
The "Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document (U.S. EPA 2017b). a public comment submitted to the NMP risk evaluation docket (Gerber.
2017). and the 2017 market profile on NMP (Abt. 2017) identify the following printing products:
• Two inkjet inks, each less than five weight percent NMP;
• Inkjet ink, one to five weight percent NMP;
• Inkjet ink, five to 10 weight percent NMP;
• High performance silver ink, up to five weight percent NMP; and
• Unspecified printing ink, less than five weight percent NMP.
Based on these data, for printing activities, EPA assumes a typical (50th percentile) of five weight
percent NMP and a worst-case (95th percentile) weight fraction of 7 percent NMP in printing inks. For
use of NMP in writing utensils, the "Preliminary Information on Manufacturing, Processing,
Distribution, Use, and Disposal: NMP" document (U.S. EPA. 2017b) and 2017 market profile on NMP
(Abt. 2017) identified one marker containing NMP at 10 to 20 weight percent. No other writing products
containing NMP were identified. Thus, EPA assumes a low-end composition of 10 weight percent NMP
and a high-end composition of 20 weight percent NMP.
Skin Surface Area and Glove Usage
For printing, as described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for
females and 1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535
cm2 for males. However, for writing, EPA does not expect that workers get writing inks on a significant
portion of their hands. Thus, based on information from a NICNAS assessment on potential consumer
exposures to writing inks, EPA assesses that 1 cm2 of skin surface area may be exposed to writing inks
(Australian Government Department of Health. 2016). for both females and males.
The PPE information described in Section 2.9.2.1 indicates that workers may or may not wear gloves
during printing activities. Additionally, EPA does not expect that workers wear gloves during use of
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markers and other writing utensils that use inks containing NMP. Thus, EPA assesses that no gloves are
used for the high-end exposure scenario, corresponding to a protection factor of 1 from Table 1-2 of
Section 1.4.3.2.3. EPA expects that workers may potentially wear gloves but does not know the
likelihood that workers wear gloves of the proper material and have training on the proper usage of
gloves. No information on employee training was found, but due to the likely commercial nature of
these uses, EPA expects minimal to no employee training. Based on this information EPA assesses a
central tendency protection factor of 5 from Table 1-2 of Section 1.4.3.2.3. EPA did not find data on the
use of gloves for this occupational exposure scenario and the glove protection factor assumptions are
based on professional judgment. The assumed glove protection factor values are highly uncertain.
Exposure Duration
For printing activities, EPA identified monitoring data in Appendix A.9 that identifies worker inhalation
exposure data that range in duration from 4 hr/day up to 8 hr/day. Thus, for the central tendency
scenario, EPA assumes that incidental exposure can occur at such a frequency that the dermal exposure
duration is 4 hours. For the high-end exposure scenario, EPA assumes that incidental exposures can
occur at such a frequency that the dermal exposure duration is over an entire shift of 8 hours.
For writing, as EPA assumed one dermal contact event as low-end exposure scenario. Thus, the
exposure duration is assumed to be the approximate time for evaporation of NMP from skin, or half an
hour. EPA does not assess duration of exposure during writing exceeding this time.
Table 2-47. Summary of Parameters for Worker Dermal Exposure to Liquids During Printing
Work
Activity
Parameter
Characterization
Glove
Protection
Factor (s)
NMP
Weight
Fraction
Skin Surface
Area Exposed
a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Printing
Central Tendency
5
0.05
445 (f)
535 (m)
4
74 (f)
High-End
1
0.07
890 (f)
1,070 (m)
8
88 (m)
Writing
Central Tendency
5
0.1
lb
0.5
74 (f)
High-End
1
0.2
lb
0.5
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
b This surface area was assumed based on (Australian Government Department of Health. 2016).
2.9.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-48.
The numeric parameters corresponding to the characterizations presented in Table 2-48 are summarized
in Table 2-49. These are the inputs used in the PBPK model.
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Table 2-48. Characterization of PBPK Model Input Parameters
'or Print
ting and Writing
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Printing
Central tendency (50th
percentile)
Based on 4-
hour TWA
data
1-hand
Yes
Central Tendency
High-end
Printing
High-end (95th
percentile)
Based on 8-
hour TWA
data
2-hand
No
High-end
Central
Tendency
Writing
Inhalation Exposure
Not Assessed
Based on
one contact
event
1 cm2
Yes
Central Tendency
High-end
Writing
Inhalation Exposure
Not Assessed
Based on
one contact
event
1 cm2
No
High-end
Table 2-49. PBPK Model Input Parameters for Printing and Writing
Scenario
Activity
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
Printing
0.016
4
445 (f)
535 (m)
5
0.05
74 (f)
88 (m)
High-end
Printing
0.172
8
890 (f)
1,070 (m)
1
0.07
74 (f)
88 (m)
Central Tendency
Writing
0
0.5
1
5
0.1
74 (f)
88 (m)
High-end
Writing
0
0.5
1
1
0.2
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.9.4 Summary
In summary, dermal exposure and inhalation are expected for use of NMP in printing. Only dermal
exposure is expected for use of NMP in writing activities. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.10 Soldering
2.10.1 Process Description
The 2017 market profile for NMP and the "Preliminary Information on Manufacturing, Processing,
Distribution, Use, and Disposal: NMP" document identifies one soldering flux product with an NMP
concentration ranging from 1.0 to 2.5 weight percent, used in professional applications (Abt. 2017; U.S.
EPA 2017b Y
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The North America's Building Trades Unions (NABTU) submitted a public comment to the NMP risk
evaluation docket that indicates solder materials containing NMP may be used in the construction
industry, including in plumbing work ( ). The RIVM Annex XV Proposal for a Restriction
- NMP report indicates that the Finnish product registry identified around four NMP-based welding and
soldering products, the composition and industries of application of which are unknown (RIVM. 2013).
Soldering is a process in which two or more substrates, or parts (usually metal), are joined together by
melting a filler metal material (solder) into the joint and allowing it to cool, thereby joining the
independent parts. The solder has a lower melting point than the adjoining metal substrates. Soldering
differs from welding in that soldering does not involve melting the work pieces. Solder (or soldering
flux) is applied to the metal substrates in a variety of methods. The manufacturer and distributor of the
solder flux containing NMP that was described above indicates the soldering flux formula is designed to
be used (dispensed) with a rotating disc, a doctor blade, or a drum fluxer
(https://www.kester.com/products/prodiict/tsf-6522). This product may also be dispensed with a syringe
or a dot dispensing system.
2.10^2 Exposure Assessment
2.10.2.1 Worker Activities
Workers are potentially exposed to NMP in soldering formulations during the application of solder flux
onto the substrate to be soldered. This activity is a potential source of worker exposure through dermal
contact, vapor-through-skin, and inhalation of NMP vapors. Workers are also potentially exposed to
NMP vapors during the soldering process, which occurs at an elevated temperature, increasing the
potential for NMP vapor production and associated worker inhalation exposure potential.
EPA did not find information regarding the use of engineering controls or worker PPE during the use of
NMP-based soldering products. The safety datasheet (SDS) for the soldering product identified above
recommends the use of nitrile or natural rubber gloves and safety glasses with side shields
(http://www.kester.com/DesktopModules/Bring2mind/DMX/Download.aspx?Command=Core Pownlo
ad&Entry!d=l 169&language=en-US&PortalId=0&TabId=96). The SDS also indicates that respiratory
protection is not needed if the room is well ventilated.
ONUs include employees that work at the sites where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
supervisors, managers, and other employees that may be in the production areas but do not perform tasks
that result in the same level of exposures as those workers that engage in tasks related to the use of
NMP.
2.10.2.2 Number of Potentially Exposed Workers
As discussed in Section 2.10, soldering products containing NMP may be used in the construction
industry, which is covered within the 2-digitNAICS group 23, construction. Within this NAICS group,
EPA identified the 4-digit NAICS groups that are most likely to perform soldering activities. EPA
compiled these identified NAICS codes in Table 2-50. EPA determined the number of workers
associated with each industry identified using Bureau of Labor Statistics" OES data (U.S. BLS. 2016)
and the U.S. Census" SUSB (U.S. Census Bureau. 2015). The number of establishments within each
industry that use NMP-based soldering products and the number of employees within an establishment
exposed to these NMP-based products are unknown. Therefore, EPA provides the total number of
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establishments and employees in these industries as bounding estimates of the number of establishments
that use and the number of employees that are potentially exposed to NMP-based soldering products.
These bounding estimates are likely overestimates of the actual number of establishments and
employees potentially exposed to NMP during soldering.
Tab
e 2-50. US Number of Establishments and Employees for Soldering
Number
Number
of
ONUs
per Site
b
Industry
2016
NAICS
2016 NAICS Title
Number of
Establishments
of
Workers
Sitea
2361
Residential Building Construction
164,519
3
1
2362
Nonresidential Building
Construction
41,767
11
1
2371
Utility System Construction
19,585
21
2
Construction
2373
Highway, Street, and Bridge
Construction
9,804
20
2
2379
Other Heavy and Civil Engineering
Construction
4,331
15
1
2381
Foundation, Structure, and Building
Exterior Contractors
87,703
7
1
2382
Building Equipment Contractors
176,142
8
1
2389
Other Specialty Trade Contractors
66,339
6
1
Total number of establishments, workers, and ONUs
potentially exposedc
570,000
4,000,000
380,000
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a Rounded to the nearest worker. No 2016 BLS data found for this NAICS. EPA determined number of workers per site by
dividing the total number of employees by the total number of establishments from the available SUSB data for the 2-digit
NAICS group.
b Rounded to the nearest worker. No 2016 BLS data found for this NAICS. EPA determined number of ONUs per site by
dividing the total number of employees by the total number of establishments from the available SUSB data for the 2-digit
NAICS group.
0 Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.10.2.3 Occupational Exposure Assessment Methodology
2.10.2.3.1 Inhalation
Appendix A. 10 summarizes the inhalation monitoring data for NMP-based soldering that EPA compiled
from published literature sources. While the identified monitoring data may be potentially relevant to
this scenario, EPA did not find information on the specific worker activity descriptions that correlate to
these exposure concentrations. Due to this lack of information, EPA excludes the data presented in
Appendix A. 10, as EPA cannot determine with confidence that these data relate to soldering activities.
Due to the low NMP content in the one identified soldering production containing NMP (one to 2.5
weight percent NMP), the potential for worker and ONU inhalation exposures is likely small. In
addition, some of the NMP may be destroyed in the soldering process, further mitigating the potential
for inhalation exposures. Thus, EPA does not assess potential inhalation exposures during soldering.
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2.10.2.3.2 Dermal
Table 2-51 summarizes the parameters used to assess dermal exposure during the use of soldering
products containing NMP. EPA assessed dermal exposure to NMP at the specified liquid weight
fraction, skin surface area, and exposure duration.
NMP Weight Fraction
The 2017 market profile for NMP (Abt 2017) and the 2017 document on the "Preliminary Information
on Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (U.S. EPA 2017b)
identified one soldering product containing NMP at a concentration of one to 2.5 weight percent. Due to
lack of additional information, EPA assesses a low-end concentration of one percent and a high-end
concentration of 2.5 percent.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. EPA did not find information on the use of gloves. Thus, EPA assesses that no gloves are used
for the high-end exposure scenario, corresponding to a protection factor of 1 from Table 1-2 of Section
1.4.3.2.3. EPA expects that workers may potentially wear gloves but does not know the likelihood that
workers wear gloves of the proper material and have training on the proper usage of gloves. No
information on employee training was found, but due to the commercial nature of this use, EPA expects
minimal to no employee training. Based on this information EPA assesses a central tendency protection
factor of 5 from Table 1-2 of Section 1.4.3.2.3. EPA did not find data on the use of gloves for this
occupational exposure scenario and the glove protection factor assumptions are based on professional
judgment. The assumed glove protection factor values are highly uncertain.
Exposure Duration
EPA did not find data on exposure duration. As described in Section 1.4.3.2.4, EPA assumes a high-end
exposure duration of eight hours and a central tendency exposure duration of four hours.
Table 2-51. Summary of Parameters for Worker Dermal Exposure During Soldering
Work
Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area Exposed
a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Soldering
Central Tendency
5
0.01
445 (f)
535 (m)
4
74 (f)
88 (m)
High-End
1
0.025
890 (f)
1,070 (m)
8
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.10.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-52.
The numeric parameters corresponding to the characterizations presented in Table 2-52 are summarized
in Table 2-53. These are the inputs used in the PBPK model.
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Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Soldering
Inhalation Exposure
Not Assessed
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Soldering
Inhalation Exposure
Not Assessed
Assumed 8
hours
2-hand
No
High-end
Table 2-53. PBPK Model Input Parameters for Soldering
Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
0
4
445 (f)
535 (m)
5
0.01
74 (f)
88 (m)
High-end
0
8
890 (f)
1,070 (m)
1
0.025
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
^.10.4 Summary
In summary, only dermal exposure is expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.11 Commercial Automotive Servicing
2.11.1 Process Description
NMP is used in a variety of automotive service operations. The "Preliminary Information on
Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (U.S. EPA 2017bI 2017
market profile for NMP (Abt 20171 and the 2017 Scope of the Risk Evaluation for NMP (U.S. EPA
2017c) identified multiple automotive servicing products that contain NMP. These products and the
associated methods of use are described further in this section.
The "Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document and 2017 market profile for NMP identified two sealants, with concentrations of less than one
weight percent and 0.1 to one weight percent, respectively (Abt 2017: U.S. EPA 2017b). One sealant is
a paste and is thus likely to be manually applied from the package in discrete quantities or using a trowel
or other tool. The other sealant is an aerosol leak sealer that could potentially be used in the automotive
servicing industry. EPA does not have any additional data on these products or potential worker
exposures during the use of these products. Due to a lack of specific information for this scenario, EPA
does not assess potential exposures during the manual application of paste sealant. EPA assessed
potential exposures during manual brush or roller application of a paste in Section 2.14.3 on Wood
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Preservatives, which EPA expects to be the most representative of potential exposures during
application of paste sealants based on the available information.
The "Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document and 2017 market profile for NMP identified multiple automotive cleaning products, including
three leather cleaners that contain from 0.1 to four weight percent of NMP, one air intake cleaner that
contains 15 to 40 weight percent NMP, and one automotive headlight cleaner that contains 0.2 weight
percent NMP (Abt. _^ j«i t:). The product details do not specify the methods of
application. EPA expects the most applicable methods of application for these products to be spray then
wiping or polishing and aerosol cleaning. EPA assessed potential exposures during spray / wipe cleaning
in Section 2.10, thus does not reassess these exposures in this scenario because EPA did not find
additional monitoring data specific to automotive cleaning.
In addition to the products listed above, the Scope of Risk Evaluation of NMP, which refers to 2016
CDR results as well as public comments on the NMP docket, indicates that NMP is used in the
following automotive products: paints / coatings / adhesives, strippers, anti-freeze and de-icing products,
and lubricants (MacRov. 2017: U.S. EPA. 2017c). EPA assessed application of paints, coating, and
adhesives in Section 2.5 and paint stripping in Section 2.6; EPA did not assess these exposures in this
scenario because no new information was found that would result in differing exposure estimates from
those already assessed.
EPA expects that some of the above products may be used as aerosols. Additionally, the California Air
Resources Board (CARB) surveyed automotive brake cleaner manufacturers and automotive repairs
shops as part of a rulemaking to mitigate air releases of certain chlorinated solvents used in aerosol
cleaning products by automotive maintenance and repair shops (CARB, 2000). CARB's survey of
automotive maintenance and repair shops included a compilation of safety data sheets of brake cleaners,
carburetor and air intake cleaners, engine degreasers, and general purpose degreasers used in California
at the time of the survey. NMP was identified as a component of unspecified formulations in this survey.
Thus, it is feasible that NMP is used in aerosol applications during automotive servicing.
Aerosol activities typically involve the application of a solution from pressurized cans or bottles that use
propellant to aerosolize the solution, allowing it to be sprayed onto substrates. Based on identified safety
data sheets (SDS) for cleaning products, NMP-based formulations typically use liquified petroleum gas
(LPG) (i.e., propane and butane) as the propellant (AM. 2017: U.S. EPA. 2017b).
EPA did not assess aerosol exposures in other conditions of use; thus, EPA presents potential exposures
for the use of aerosols in this scenario.
2.11.2 Exposure Assessment
2.11.2.1 Worker Activities
Workers may be potentially exposed to NMP during multiple activities involved in automotive
servicing, including the application of cleaning, lubricant, and other servicing formulations onto car
parts, as well as any subsequent wiping, polishing, or maintenance activities that occur once the
formulation has been applied to the car parts. These activities are potential sources of worker exposure
through dermal contact, vapor-through-skin, and inhalation of NMP mists and vapors.
EPA identified limited information on the use of PPE and engineering controls at automotive service
sites. The Draft ESD on Chemical Additives used in Automotive Lubricants indicates that workers in
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automotive servicing shops are likely to wear disposable gloves and protective footwear (OECD. 2017).
Workers may also use protective headwear when working in pits, under lifts, or hoisting machinery. The
ESD did not identify typical PPE used but indicates that breathing protection may include dust masks or
respirators, if workers are handling highly volatile substances.
ONUs include employees that work at the automotive servicing shops where NMP is used, but they do
not directly handle the chemical and are therefore expected to have lower inhalation exposures and
vapor-through-skin uptake and are not expected to have dermal exposures by contact with liquids.
ONUs for this scenario include supervisors, managers, and other mechanics that may be in the
automotive servicing areas but do not perform tasks that result in the same level of exposures as those
workers that engage in tasks related to the use of NMP.
2.11.2.2 Number of Potentially Exposed Workers
This section identifies worker population estimates for use of NMP-based automotive servicing
formulations. Application of these products are expected to occur at automotive servicing shops, which
fall within the NAICS group 8111, Automotive Repair and Maintenance. The 6-digit NAICS codes
within this group include both automotive servicing and automotive body work. While EPA expects that
the use of aerosols is largely within the automotive servicing sector, workers at automotive body shops
may still be exposed to NMP in paints and sealants. Thus, EPA includes these NAICS in the worker
estimates provided in this section.
Additionally, because EPA is including aerosol cleaning / degreasing within this scenario, EPA included
industries beyond the automotive servicing sector that are expected to perform aerosol degreasing
activities. Specifically, EPA identified additional industries in which aerosol degreasing may occur from
the 2016 Risk Assessment on Spray Adhesives, Dry Cleaning, and Degreasing Uses of 1-BP (U.S. EPA
2016c).
EPA compiled the associated NAICS codes for the identified industries in Table 2-54. The number of
workers associated with each industry using Bureau of Labor Statistics' OES data (U.S. BLS. 2016) and
the U.S. Census' SUSB (U.S. Census Bureau. 2015). The number of establishments within each industry
that use NMP-based aerosol products and the number of employees within an establishment exposed to
these NMP-based products are unknown. Therefore, EPA provides the total number of establishments
and employees in these industries as bounding estimates of the number of establishments that use and
the number of employees that are potentially exposed to NMP-based aerosol products. These bounding
estimates are likely overestimates of the actual number of establishments and employees potentially
exposed to NMP during use of aerosol products.
Table 2-54. US Number of Establishments and Employees for Commercial Automotive Servicing
Industry
2016
NAICS
a
2016 NAICS Title
Number of
Establishment
s
Number
of
Workers
per Site b
Number
of
ONUs
per Site
b
Automotive
Servicing
441110
Automobile Dealers
46,531
6
1
811111
General Automotive Repair
80,243
2
0
811112
Automotive Exhaust System Repair
1,907
2
0
811113
Automotive Transmission Repair
4,684
2
0
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Industry
2016
NAICS
a
2016 NAICS Title
Number of
Establishment
s
Number
of
Workers
per Site b
Number
of
ONUs
per Site
b
811118
Other Automotive Mechanical and Electrical
Repair and Maintenance
3,839
2
0
811121
Automotive Body, Paint, and Interior Repair
and Maintenance
33,648
3
0
811122
Automotive Glass Replacement Shops
6,106
2
0
811191
Automotive Oil Change and Lubrication Shops
8,380
4
0
811192
Car Washes
15,902
5
0
811198
All Other Automotive Repair and Maintenance
4,140
2
0
Other
Industries
Conducting
Aerosol
Degreasing
811211
Consumer Electronics Repair and Maintenance
1,814
3
0
811212
Computer and Office Machine Repair and
Maintenance
5,195
4
0
811213
Communication Equipment Repair and
Maintenance
1,604
5
1
811219
Other Electronic and Precision Equipment
Repair and Maintenance
3,470
6
1
811310
Commercial and Industrial Machinery and
Equipment (except Automotive and Electronic)
Repair and Maintenance
21,721
5
1
811411
Home and Garden Equipment Repair and
Maintenance
1,735
1
1
811490
Other Personal and Household Goods Repair
and Maintenance
9,943
1
1
451110
Sporting Goods Stores
21,890
1
0
Total establishments and number of potentially exposed workers and
ONUs =c
270,000
910,000
110,000
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Source: (U.S. EPA. 2016c)
b - Rounded to the nearest whole number.
c - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.11.2.3 Occupational Exposure Assessment Methodology
2.11.2.3.1 Inhalation
EPA did not find monitoring data for the use of NMP products during automotive servicing. Because
EPA did not find relevant monitoring data monitoring data for this use in the published literature, EPA
used modeling estimates with the highest data quality to assess exposure for this use, as described
below.
In lieu of monitoring data, EPA modeled potential occupational inhalation exposures for workers and
ONUs using EPA's model for Occupational Exposures during Aerosol Degreasing of Automotive
Brakes. This model uses a near-field/far-field approach, where an aerosol application located inside the
near-field generates a mist of droplets, and indoor air movements lead to the convection of the droplets
between the near-field and far-field. Workers are assumed to be exposed to NMP droplet concentrations
in the near-field, while ONUs are exposed at concentrations in the far-field. This model involves
probabilistic modeling. Appendix A. 11 includes some background information on this model, EPA's
rationale for using this model, and the model results.
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The results of this modeling are summarized for workers in Table 2-55 and for ONUs in Table 2-56.
This model calculates both 8-hour TWA and 1-hour TWA exposure concentrations. For workers, EPA
uses the 50th and 95th percentile model results in Table 2-55 to represent central tendency and worst-case
inhalation exposures, respectively. Consistent with the approach for other OESs, EPA uses the central
tendency worker air concentration to evaluate ONU exposure and further refines this estimate using far-
field modeling or applicable area monitoring data if needed due to risk. Refinement was not necessary
for this OES.
Table 2-55. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Commercial Aul
tomotive Servicing
Work
Activity
Parameter
Characterization
Full-Shift NMP
Air
Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Aerosol
Degreasing
Central tendency
(50th percentile)
6.39
19.96 (duration =
1 hr)
Occupational
Exposures during
Aerosol Degreasing
of Automotive Brakes
Model
Not
applicable3
High-end (95th
percentile)
43.4
128.8 (duration =
1 hr)
a - EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically review models
that were developed by EPA.
Table 2-56. Summary of Occupational Non-User Inhalation Exposure During Commercial
Automotive Servicing
Work
Activity
Parameter
Characterization
Full-Shift NMP
Air
Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Aerosol
Degreasing
Central Tendency
0.13
0.40 (duration = 1
hr)
Occupational
Exposures during
Aerosol Degreasing
of Automotive Brakes
Model
Not
applicable3
High-end
1.57
4.71 (duration = 1
hr)
a - EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically review models
that were developed by EPA.
2.11.2.3.2 Dermal
Table 2-57 summarizes the parameters used to assess dermal exposure during cleaning activities. EPA
assumed that the skin was exposed dermally to NMP at the specified liquid weight fraction, skin surface
area, and exposure duration.
NMP Weight Fraction
As discussed in Section 2.13.1.1, EPA identified two aerosol cleaning products containing NMP at
concentrations of 4.5 weight percent and between 35 and 40 weight percent. EPA identified multiple
additional automotive care products ranging in NMP concentration from 0.1 to 40 weight percent. Based
on this information, EPA calculated typical (50th percentile) and worst-case (95th percentile) weight
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percent of NMP to be 2.5 and 33, respectively. Note that, where NMP concentration was provided in a
range, EPA used the midpoint of the range for the calculations of typical and worst-case NMP
concentration. The underlying data used for these estimates have an overall confidence rating of high.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. As described in Section 2.11.2.1, EPA did not find information on the typical usage of gloves in
the automotive servicing industry. Due to the wide-spread use of NMP-based products in this scenario,
EPA assumes that no gloves are used for the worst-case exposure scenario. Thus, EPA assesses that no
gloves are used for the high-end exposure scenario, corresponding to a protection factor of 1 from Table
1-2 of Section 1.4.3.2.3. EPA expects that workers may potentially wear gloves but does not know the
likelihood that workers wear gloves of the proper material and have training on the proper usage of
gloves. No information on employee training was found, but due to the wide-spread nature of this use,
EPA expects minimal to no employee training. Based on this information EPA assesses a central
tendency protection factor of 5 from Table 1-2 of Section 1.4.3.2.3. EPA did not find data on the use of
gloves for this occupational exposure scenario and the glove protection factor assumptions are based on
professional judgment. The assumed glove protection factor values are highly uncertain.
Exposure Duration
Based on EPA's model for Occupational Exposures during Aerosol Degreasing of Automotive Brakes
described in Appendix A. 11, EPA modeled worker inhalation exposure over 8 hr/day (based on a full
shift) and 1 hr/day (based on the length of time for aerosol degreasing of one job).
Table 2-57. Summary of Parameters for Worker Dermal Exposure to Liquids During Commercial
Automotive Servicing
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Commercial
Automotive
Servicing
Central Tendency
5
0.025
445 (f)
535 (m)
1
74 (f)
High-End
1
0.33
890 (f)
1,070 (m)
8
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.11.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-58.
The numeric parameters corresponding to the characterizations presented in Table 2-58 are summarized
in Table 2-59. These are the inputs used in the PBPK model.
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Table 2-58. Characterization of PBPK Model Input Parameters for Commercial Automotive
Servicing
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Aerosol
degreasing
Central tendency
(50th percentile)
Based on
time for one
job
1-hand
Yes
Central Tendency
High-end
Aerosol
degreasing
High-end (95th
percentile)
Assumed 8
hours
2-hand
No
High-end
Scenario
Activity
Duration-
Based NMP
Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2)a b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
Aerosol
degreasing
19.96
1
445 (f)
535 (m)
5
0.025
74 (f)
88 (m)
High-end
Aerosol
degreasing
43.4
8
890 (f)
1,070 (m)
1
0.33
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.11.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.12Laboratory Use
2.12.1 Process Description
The 2017 Scope Document for the Risk Evaluation for NMP (U.S. EPA. 2017c) and the "Preliminary
Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (U.S.
EPA 2017b) both indicate that NMP is used in laboratories, but do not identify any specific products
that are marketed for laboratory use. Additionally, no NMP-based laboratory chemicals were identified
in the 2017 market profile on NMP (Abt 2017).
EPA found limited information on the function of NMP in laboratory chemicals. The Scope Document
(U.S. EPA 2017c) identifies one public comment to the NMP risk evaluation from the Motor &
Equipment Manufacturers Association (MEMA), which states that NMP is used as a carrier in chemical
analyses for research and development within the automotive industry (Holmes. 2017). A health study
published in the Journal of Occupational Medicine indicates NMP was used to dissolve solid samples,
which were analyzed in atomic absorption spectrophotometers, and subsequently discarded as hazardous
waste (Solomon et al.. 1996). In this application, NMP was poured by the laboratory technician from 5-
gallon containers through an ion exchange column for filtering before use.
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Based on the information found, NMP is likely used in laboratories largely as a carrier chemical, which
is a media in which samples are prepared for analysis. EPA did not find information indicating that
NMP is used as a reagent, which is consumed to some extent in laboratory research activities.
2,12,2 Exposure Assessment
2.12.2.1 Worker Activities
Workers may be potentially exposed to NMP in laboratories during multiple activities, including
unloading of NMP from the containers in which they were received, transferring NMP into laboratory
equipment (i.e., beakers, flasks, other intermediate storage containers), dissolving substances into NMP
or otherwise preparing samples that contain NMP, analyzing these samples, and discarding the samples.
In addition, NMP may be used to clean glassware, which is likely done manually by workers. These
activities are potential sources of worker exposure through dermal contact, vapor-through-skin, and
inhalation of NMP vapors.
The RIVM Annex XV Proposal for a Restriction - NMP report assessed potential worker exposures to
NMP during use in laboratories (RIVM. 2013). While this report does not have information from
industries on the type of engineering controls and worker PPE employed, RIVM does consider the use
of LEV in its assessment of potential worker exposures in laboratories. EPA expects that some
laboratories may use fume hoods.
The health study report at a laboratory that uses NMP to dissolve solid photoresist for quality testing
indicates that the lab uses LEV in some, but not all, areas within the lab (Solomon et at... 1996). The
report also indicates that workers in the lab typically wear a lab coat, safety goggles, and latex gloves,
and occasionally use a half-face air-purifying respirator.
ONUs include employees that work at the sites where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
supervisors, managers, and other employees that may be in the laboratory but do not perform tasks that
result in the same level of exposures as those workers that engage in tasks related to the use of NMP.
2.12.2.2 Number of Potentially Exposed Workers
EPA found limited information on the industries that use of NMP-based products in laboratories. The
public comment to the NMP risk evaluation docket from the Motor & Equipment Manufacturers
Association (MEMA) indicates that NMP is used for research and development within the automotive
industry (Holmes. 2017).
Based on this information, EPA expects the NMP is used in professional laboratories and within the
automotive manufacturing industry. The use of NMP for research and development in other industries is
unknown. EPA compiled the associated NAICS codes for the identified industries in Table 2-60. The
number of workers associated with each industry using Bureau of Labor Statistics" OES data (U.S. BLS.
2016) and the U.S. Census" SUSB ( isus Bureau. 2015). The number of establishments within
each industry that use NMP and the number of employees within an establishment exposed to NMP are
unknown. Therefore, EPA provides the total number of establishments and employees in these industries
as bounding estimates of the number of establishments that use and the number of employees that are
potentially exposed to NMP in a laboratory setting. These bounding estimates are likely overestimates of
the actual number of establishments and employees potentially exposed to NMP in laboratories.
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Table 2-60. US Number of Establishments and Employees for Laboratory Use
Industry
2016
NAICS
2016 NAICS Title
Number of
Establishments
Number
of
Workers
Site a
Number
of
ONUs
per Site
a
Automotive
Research &
Development
336100
Motor Vehicle Manufacturing
340
235
99
336200
Motor Vehicle Body and Trailer
Manufacturing
1,917
41
7
336300
Motor Vehicle Parts Manufacturing
5,088
51
15
Professional
Laboratories
541380
Testing Laboratories
6844
1
9
Total number of establishments, workers, and ONUs
potentially exposed b
14,000
420,000
180,000
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest worker. No 2016 BLS data found for this NAICS. EPA determined number of workers per site by
dividing the total number of employees by the total number of establishments from SUSB data.
b - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.12.2.3 Occupational Exposure Assessment Methodology
2.12.2.3.1 Inhalation
Appendix A. 12 summarizes EPA's methodology for determining potential worker inhalation exposure
concentrations during this scenario. EPA only found one data source that had inhalation monitoring data,
representing the preparation of NMP for use in samples, sample preparation involving the dissolving of
solids in NMP, and sample analysis. This sample result is used as input into the PBPK model for 2-hour
exposure duration. EPA did not find additional monitoring data, thus used a modeled exposure for the
use of NMP in a laboratory setting from the RIVM Annex Xlr Proposal for a Restriction - NMP report
(RIVM 2013) to represent 8-hour NMP exposure concentration. As the quality of both the monitoring
and modeled data is acceptable, EPA used all available data to assess this scenario.
The monitoring data and modeled exposure summarized in Table 2-61 are the input parameters used for
the PBPK modeling. Note that EPA assesses full-shift exposure duration and a 2-hour exposure duration
based on the available monitoring data (Solomon et al.. 1996) (two hours is the duration of the sampled
task - sample preparation and analysis).
Table 2-61. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Laboratory Use
Work
Activity
Parameter
Characterization
Full-Shift NMP
Air Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Laboratory
Use
Central tendency
(unknown statistical
characterization)
2.07
0.200 (duration = 2
hr)
(Solomon et
al.. 1996)
Medium
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High-end (unknown
(RIVM.
2013)
statistical
4.13
No data
High
characterization)
2.12.2.3.2 Dermal
Table 2-62 summarizes the parameters used to assess dermal exposure during use of NMP in
laboratories. EPA assumed that the skin was exposed dermally to NMP at the specified liquid weight
fraction, skin surface area, and exposure duration.
NMP Weight Fraction
EPA found limited information on the concentration of NMP carrier and reagent solutions used in
laboratories. Neither the 2017 market profile on NMP (Abt 2017) nor the "Preliminary Information on
Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (U.S. EPA 2017b) any
NMP products that are marketed for laboratory use. Because NMP is used as a carrier chemical, EPA
expects that NMP may be used in pure form (i.e., 100 percent NMP). This assumption was also used by
RIVM in the Proposal for Restriction of NMP report (RIVM. 2013). While NMP may be used in
concentrations below 100 weight percent, EPA did not find additional information on these potential
concentrations.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. Because laboratories have procedures and trainings to ensure accuracy and quality of the
performed analyses, EPA expects workers are likely to wear protective gloves and have basic training on
the proper usage of these gloves, corresponding to a protection factor of 10 from Table 1-2 of Section
1.4.3.2.3. Thus, EPA assesses a protection factor 10 for both the central tendency and high-end scenarios
for this scenario. EPA did not find data on the use of gloves for this occupational exposure scenario and
the glove protection factor assumptions are based on professional judgment. The assumed glove
protection factor values are highly uncertain.
Exposure Duration
EPA found one task-based inhalation monitoring data point (for the preparation and analysis of a sample
containing NMP) indicating an exposure duration of two hours. EPA uses this exposure duration for the
central tendency scenario. For the high-end scenario, EPA assumes eight hours, as described in Section
1.4.3.2.4.
Table 2-62. Summary of Parameters for Worker Dermal Exposure During Laboratory Use
Work
Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area Exposed
a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Laboratory
Central tendency
10
1
445 (f)
535 (m)
2
74 (f)
Use
High-end
10
1
890 (f)
1,070 (m)
8
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
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2.12.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-63.
The numeric parameters corresponding to the characterizations presented in Table 2-63 are summarized
in Table 2-64. These are the inputs used in the PBPK model.
Table 2-63. Characterization of PBPK Model Input Parameters by Laboratory Use
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Laboratory
activities
Central tendency
(unknown statistical
characterization)
Based on 2-
hour TWA
data
1-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
High-end
Laboratory
activities
High-end (unknown
statistical
characterization)
Assumed 8
hours
2-hand
Yes
N/A - 100% is
assumed for both
exposure scenarios
Table 2-64. PBPK Model Input Parameters for Laboratory Use
Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2)a b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
0.200
2
445 (f)
535 (m)
10
1
74 (f)
88 (m)
High-end
4.13
8
890 (f)
1,070 (m)
10
1
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
^.12.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.13 Cleaning
2.13.1 Process Description
NMP may be used in a variety of cleaning products that can be used in multiple occupational
applications, including industrial facilities and commercial shops. EPA identified the following distinct
NMP-containing cleaning products with expected occupational applications:
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• Aerosol degreasing
• Dip degreasing and cleaning products
• Wipe cleaning, including use of spray-applied cleaning products
2.13.1.1 Aerosol Degreasing
EPA's 2017 market profile for NMP (Abt, 2017) and "Preliminary Information on Manufacturing,
Processing, Distribution, Use, and Disposal: NMP" document (U.S. EPA. 2017b) identified three
aerosol cleaning products containing NMP. One product is listed as a bore cleaning foam with 4.5
weight percent NMP (Abt 2017; U.S. EPA. 2017b). Another product is listed as an aerosol stainless
polish with an unknown concentration of NMP (U.S. EPA. 2017b). The final product is listed as a resin
remover used as an aerosol with a concentration of 35 to 40 weight percent NMP (Abt 2*-' L , 1 v < < ^
2017b). A public comment on the NMP risk evaluation docket from CRC Industries, Inc. indicates that
NMP is present at less than 20 weight percent in their gasket removal products (Rudnick. 2017).
EPA did not find monitoring data for the use of the above-listed aerosol cleaners and did not identify
information that clearly defines scenarios in which these aerosol cleaners are used. However, EPA has
identified NMP as a potential ingredient in aerosol brake cleaners (see Section 2.11). Therefore, EPA
assesses potential inhalation exposures during the aerosol cleaning of automotive brakes and assesses
these potential exposures as surrogate for miscellaneous aerosol cleaning. Section 2.11 presents the
assessment of aerosol brake cleaning.
2.13.1.2 Dip Degreasing and Cleaning
NMP has historically been used for the degreasing of optical lenses and metal parts by dipping into a
tank containing NMP (Xiaofei et ai. 2000; BASF. 1993). A public comment to the NMP risk evaluation
docket indicates that NMP is used in the immersive cleaning of wire coating equipment at facilities that
also used NMP-based wire coatings (National Electrical Manufacturers Association. 2017).
In dip cleaning processes, the parts to be cleaned are first placed in a basket. Workers will then open the
lid of a tank containing NMP and submerge the basket into the tank (National Electrical Manufacturers
Association. 2017; Xiaofei et at.. 2000). The cleaning solution in the tank can range from 90 percent up
to 100 percent NMP and may optionally be heated (RIVM. 2013; BASF. 1993). Once the basket of parts
is submerged in the tank, the lid of the tank is closed and the parts soak in the NMP cleaning solution.
Sonication or some other form of agitation of the parts may be used to aid in the cleaning process. The
basket containing the parts is then lifted from the tank and the parts may be air dried or may be
transferred to a tank containing water to rinse the parts of any residual NMP or NMP-solubilized oil
remaining on the surfaces of the parts.
EPA's "Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document (U.S. EPA. 2017b) identified one cleaning product with an NMP concentration of 60 to 80
weight percent. EPA's 2017 market profile identified two additional products that can be used for
immersion cleaning of items such as spray gun heads (Abt. 2017). These products contain 40 to 60
weight percent NMP and >99 weight percent NMP, respectively. Additionally, literature indicates that
some dip cleaning processes use pure NMP (i.e., 100 percent NMP) (BASF. 1993).
2.13.1.3 Wipe Cleaning, Including Use of Spray-Applied Cleaning Products
Wipe cleaning involves first wetting towels or rags with cleaning solution or spraying, pouring, or
brushing the cleaning solution onto the surfaces to be cleaned. Spray products are deployed from non-
pressurized containers, such as bottles, and use a spray nozzle to discharge the liquid at a high velocity
to atomize the liquid into fine droplets. Some spray applications use an atomizing gas, such as air, to aid
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in the atomization of the liquid ( 016c). Workers then manually wipe surfaces clean with
towels and rags (Bader et at... 2006). Any residual cleaning solution on the wiped surfaces is expected to
volatilize. The dirty towels and rags may be disposed of entirely or laundered so they may be reused.
EPA found limited information regarding products that are used for wipe cleaning. The 2017 market
profile for NMP (Abt.! ) identified numerous cleaning products of unknown application type (i.e.,
aerosol, dip, wipe), ranging in NMP concentration of <1 to 100 weight percent. Based on the SDSs for
these products, EPA believes that it is feasible that these products may be spray applied or otherwise
poured onto surfaces or rags and then wiped off.
2.13,2 Exposure Assessment
2.13.2.1 Worker Activities
Worker are potentially exposed to NMP when unloading cleaning solutions from containers, mixing
and/or diluting the solutions before use, performing cleaning activities (i.e., spraying, dipping, wiping),
and associated equipment cleaning and maintenance ( A, 2013). These worker activities are potential
sources of worker exposure through dermal contact, vapor-through-skin, and inhalation of NMP vapors.
EPA did not find information on the customary engineering controls and worker PPE used in the many
industries that conduct cleaning activities. However, a public comment on the NMP risk evaluation
docket from the National Electrical Manufacturers Association (NEMA) indicates that, at facilities that
use NMP for wire coating and associated equipment cleaning, the cleaning tanks containing NMP are
enclosed and equipped with ventilation (National Electrical Manufacturers Association. 2017). This
comment also indicates that workers utilize PPE such as gloves, aprons and goggles.
ONUs include employees that work at the sites where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
supervisors, managers, and other employees that may be in the production areas but do not perform tasks
that result in the same level of exposures as those workers that engage in tasks related to the use of
NMP.
2.13.2.2 Number of Potentially Exposed Workers
This section identifies relevant industries and worker population estimates for NMP-based cleaners.
Cleaning activities are widespread, occurring in many industries. EPA determined the industries likely
to use NMP for cleaning activities from the following sources: the non-CBI 2016 CDR results for NMP
(U.S. EPA. 2016a). the 2017 market profile for NMP (Abt. 2017). process descriptions for the use of
NMP for cleaning purposes (Xiaofei et at.. 2000; BASF. 1993). and the "Preliminary Information on
Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document (U.S. EPA. 2017b). EPA
estimates the number of potentially exposed workers for aerosol cleaning activities in Section 2.11.
In some cases, the industries that distinctly perform dip cleaning and/or spray/wipe cleaning are
unknown. For these cases, EPA conservatively assumes that cleaning within these industries may
involve all cleaning scenarios. EPA compiled the associated NAICS codes for the identified industries in
Table 2-65. EPA determined the number of workers associated with each industry from using Bureau of
Labor Statistics" OES data ( 1. 2016) and the U.S. Census" SUSB (U.S. Census Bureau. 2015).
The number of establishments within each industry that use NMP-based cleaning products and the
number of employees within an establishment exposed to NMP-based cleaning products are unknown.
Therefore, EPA provides the total number of establishments and employees in these industries as
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bounding estimates of the number of establishments that use and employees potentially exposed to
NMP-based cleaning products. These bounding estimates are likely overestimates of the actual number
of establishments and employees potentially exposed to NMP during cleaning activities.
Table 2-65. US Number of Establishments and Employees for C
Occupational
Exposure
Scenario
Occupational
Exposure
Scenario
2016
NAICS
2016 NAICS Title
Number of
Establishments
Number
of
Workers
Number
of
ONUs
per Site
a
Source
per Sitea
Dip Cleaning
(Machinery,
Optical
Lenses)
(RIVM. 2013;
IF A. 2010;
Xiaofei et al..
2000)
333300
Commercial and Service
Industry Machinery
Manufacturing
2,014
14
6
(U.S. EPA.
2016a)
335100
Electric Lighting Equipment
Manufacturing
1,104
17
5
Unknown -
assumes all
cleaning
scenarios may
occur in these
industries
(U.S. EPA
335200
Household Appliance
303
102
20
2016a)
Manufacturing
(U.S. EPA
2016a)
335300
Electrical Equipment
Manufacturing
2,124
28
12
(U.S. EPA
2016a)
335900
Other Electrical Equipment
and Component
Manufacturing
2,140
23
8
(U.S. EPA
2016c)
811420
Reupholstery and furniture
repair
3,720
1
1
Total establishments and number of potentially exposed workers and
ONUs = b
11,000
190,000
71,000
eaning
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest whole number.
b - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.13.2.3 Occupational Exposure Assessment Methodology
2.13.2.3.1 Inhalation
Appendix A. 13 summarizes the inhalation monitoring data for NMP-based cleaning activities that EPA
compiled from published literature sources, including full-shift, short-term, and partial shift sampling
results. This appendix also includes EPA's rationale for inclusion or exclusion of these data in the risk
evaluation. EPA used the available monitoring data for use of NMP in cleaning that had the highest
quality rating to assess exposure for this use.
EPA used the available full-shift monitoring data and the modeled exposures for cleaning activities to
calculate central tendency (based on 50th percentile) and worst-case (based on 95th percentile) inhalation
exposure concentrations. These values are summarized in Table 2-66. EPA did not find short-term
exposure concentration data. Again, note that EPA did not assess aerosol exposures in this section, but
considers the modeled exposures in Section 2.11 to be the closest representation of these exposures
based on the available information.
Table 2-66. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Cleaning
Work
Parameter
Full-Shift NMP
Duration-Based
Source
Data
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Activity
Characterization
Air
Concentration
NMP Air
Concentration
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Dip Cleaning
/ Degreasing
Central tendency
(50th percentile)
0.99
No data
(RIVM. 2013; IFA.
2010; Nishimura et
al.. 2009; Bader et
al.. 2006; Xiaofei et
al.. 2000)
Medium
to high
High-end (95th
percentile)
2.75
No data
Spray / Wipe
Cleaning
Central tendency
(50th percentile)
1.01
No data
(RIVM. 2013; IFA.
2010; Nishimura et
al.. 2009; Bader et
al.. 2006)
Medium
to high
High-end (95th
percentile)
3.38
No data
2.13.2.3.2 Dermal
Table 2-67 summarizes the parameters used to assess dermal exposure during cleaning activities. EPA
assumed that the skin was exposed dermally to NMP at the specified liquid weight fraction, skin surface
area, and exposure duration.
NMP Weight Fraction
As discussed in Section 2.13.1, EPA identified three immersion cleaning formulations that range
concentrations of 40 to >99 weight percent NMP. Additionally, literature indicates that some dip
cleaning processes use pure NMP (i.e., 100 percent NMP) (BASF. 1993). Based on this information,
EPA calculated typical (50th percentile) and worst-case (95th percentile) weight percent of NMP to be
84.5 and 99.9, respectively. Note that, where NMP concentration was provided in a range, EPA used the
midpoint of the range for the calculations of typical and worst-case NMP concentration. The underlying
data used for these estimates have overall confidence ratings that range from medium to high.
As discussed in Section 2.13.1, EPA found limited information regarding products that are used for
spray and wipe cleaning. The 2017 market profile for NMP (Abt 2017) identified numerous cleaning
products of unknown application type (i.e., aerosol, dip, wipe), ranging in NMP concentration of 0.1 to
100 weight percent. Based on the SDSs for these products, EPA believes that it is feasible that these
products may be spray applied or otherwise poured onto surfaces or rags and then wiped off. Based on
these data, EPA calculated typical (50th percentile) and worst-case (95th percentile) weight percent of
NMP to be 31.3 and 98.9, respectively. Note that, where NMP concentration was provided in a range,
EPA used the midpoint of the range for the calculations of typical and worst-case NMP concentration.
The underlying data used for these estimates have overall confidence ratings that range from medium to
high.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. Due to the wide-spread commercial and industrial use of NMP-based cleaners, EPA assumes that
no gloves are used for the worst-case exposure scenario. Thus, EPA assesses that no gloves are used for
the high-end exposure scenario, corresponding to a protection factor of 1 from Table 1-2 of Section
1.4.3.2.3. The PPE information described in Section 2.7.2.1 indicates that workers who perform dip
degreasing wear gloves (National Electrical Manufacturers Association. 2017). EPA does not know the
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likelihood that workers wear gloves of the proper material and have training on the proper usage of
gloves. No information on employee training was found, but due to the widespread nature of this use,
EPA expects minimal to no employee training. Based on this information EPA assesses a central
tendency protection factor of 5 from Table 1-2 of Section 1.4.3.2.3. EPA did not find data on the use of
gloves for this occupational exposure scenario and the glove protection factor assumptions are based on
professional judgment. The assumed glove protection factor values are highly uncertain.
Exposure Duration
EPA did not find data on exposure duration. As described in Section 1.4.3.2.4, EPA assumes a high-end
exposure duration of eight hours and a central tendency exposure duration of four hours.
Table 2-67. Summary of Parameters for Worker Dermal Exposure to Liquids During Cleaning
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Dip Degreasing
Central Tendency
5
0.845
445 (f)
535 (m)
4
74 (f)
and Cleaning
High-End
1
0.999
890 (f)
1,070 (m)
8
88 (m)
Spray/Wipe
Central Tendency
5
0.313
445 (f)
535 (m)
4
74 (f)
Cleaning
High-End
1
0.989
890 (f)
1,070 (m)
8
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.13.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-68.
The numeric parameters corresponding to the characterizations presented in Table 2-68 are summarized
in Table 2-69. These are the inputs used in the PBPK model.
able 2-68. Characterization of PBPK Model Input Parameters for Cleaning
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Dip
cleaning
Central tendency (50th
percentile)
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Dip
cleaning
High-end (95th
percentile)
Assumed 8
hours
2-hand
No
High-end
Central
Tendency
Spray /
wipe
cleaning
Central tendency (50th
percentile)
Assumed 4
hours
1-hand
Yes
Central Tendency
High-end
Spray /
wipe
cleaning
High-end (95th
percentile)
Assumed 8
hours
2-hand
No
High-end
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Scenario
Activity
Duration-
Based NMP
Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
Dip
cleaning
1.98
4
445 (f)
535 (m)
5
0.845
74 (f)
88 (m)
High-end
Dip
cleaning
2.75
8
890 (f)
1,070 (m)
1
0.999
74 (f)
88 (m)
Central Tendency
Spray /
wipe
cleaning
2.02
4
445 (f)
535 (m)
5
0.313
74 (f)
88 (m)
High-end
Spray /
wipe
cleaning
3.38
8
890 (f)
1,070 (m)
1
0.989
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2.13.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.14 Fertilizer Application
2.14.1 Process Description
Based on information identified in the "Preliminary Information on Manufacturing, Processing,
Distribution, Use, and Disposal: NMP" document, NMP is used as a component in a variety of granular
or liquid pesticides, as well as in herbicides, fungicides, and dog flea treatments (U.S. EPA 2017b). The
2017 Scope Document for the Risk Assessment of NMP and 2016 CDR results indicate that NMP may
also be used in fertilizers (U.S. EPA 2017c. 2016a). The use of pesticides, including herbicides and
fungicides, is regulated under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and is
not assessed in this risk evaluation. The use of flea treatments is regulated by the Food and Drug
Administration (FDA). However, the use of fertilizers is under the purview of TSCA and is assessed in
this risk evaluation.
NMP is used both in the synthesis of and as a co-solvent in the formulation of agricultural chemicals
(U.S. EPA 2017c; RIVM. 2013). When used for synthesis, NMP may only be present in the final
formulation in residual quantities. When used as a co-solvent, NMP remains in the final formulation,
usually in concentrations ranging from one to 20 weight percent (U.S. EPA 2017b; RIVM. 2013). The
NMP Producers Group, Inc. submitted a comment to the NMP risk evaluation docket indicating that
NMP is used in a fertilizer additive that prevents the volatilization of urea (Roberts. 2017). The NMP
Producers Group, Inc. states that NMP comprises 15 to 45 weight percent of the fertilizer additive,
which is blended into a final fertilizer formulation at a recommended rate such that the final fertilizer
contains less than 0.1 weight percent NMP. Per the NMP Producers Group, Inc., the final fertilizer
formulations can be liquid or granular.
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Fertilizer application is based on the physical form of the fertilizer, which is typically a liquid
solution/suspension or solid (MRI. 1998). Liquid solutions are often applied from a vehicle that houses a
tank containing the fertilizer. The fertilizer is metered from the vehicle and onto fields through a
manifold of spray nozzles. Applicators may adjust these spray nozzles to manipulate the flow of
fertilizer solution. Solid fertilizers are similarly applied from vehicles containing hoppers through which
the solid fertilizers are metered. The metered fertilizer drops onto a belt that feeds into spreading
equipment. The spreaders are usually either fans through which fertilizer is propelled or long booms that
extend from the back of the vehicle that drop fertilizer onto the field.
This information relates to the automated application of fertilizers from vehicles. Fertilizers may also be
applied manually by workers using handheld spray application systems or other types of application
equipment. EPA did not find additional information regarding the extent of automated versus manual
application of NMP-containing fertilizers or other agricultural products.
2.14.2 Exposure Assessment
2.14.2.1 Worker Activities
Workers are potentially exposed to NMP in fertilizers during multiple activities. These activities include
transfers of fertilizers from storage containers into application equipment, any additional mixing
activities that may occur prior to application, application of the fertilizers, and cleaning of application
equipment that may occur after application (NIOSH J; kl\. a t 2013). These activities are potential
sources of worker exposure through dermal contact, vapor-through-skin, and inhalation of NMP vapors.
In addition, if the fertilizers are granular, workers may have potential inhalation exposures to dusts that
contain NMP during the application of these fertilizers.
The 1993 Generic Scenario (GS) on the Application of Agricultural Pesticides indicates that workers
will typically wear boots, gloves, and masks during the application of pesticides on fields (
1993). A NIOSH Health Hazard Evaluation (HHE) on the application of sea lamprey pesticides found
that workers wore eye protection (safety glasses, goggles, or face shield) and chemical resistant gloves
when mixing and applying pesticides (NIOSH. 2014). The investigation also included the application of
granular pesticides, for which workers were observed wearing NIOSH-approved full facepiece dual
cartridge (particulate and organic vapor) respirators. EPA expects that similar PPE may be employed for
workers who apply fertilizers.
The RIVM Annex XV Proposal for a Restriction - NMP report recommends that workers who manually
apply agrochemicals by spraying and fogging wear protective coveralls and a respirator (RIVM. 2013).
For workers that apply agrochemicals from an automated vehicle, the report recommends that workers
do so from a vented cab supplied with filtered air. Additionally, the report indicates that workers should
wear gloves for all work where dermal contact is possible.
EPA did not find information on the extent of use of the above engineering controls and PPE within the
fertilizer application industry.
ONUs include farmers that work at the farms where NMP is used, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for this scenario include
farm managers and other farmers that may be near the fields that are receiving fertilizer application, but
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do not perform tasks that result in the same level of exposures as those workers that apply fertilizer
containing NMP.
2.14.2.2 Number of Potentially Exposed Workers
Fertilizer products containing NMP are used in the agricultural industry on crop farms (as opposed to
cattle farms). These farms are covered within the 3-digit NAICS group 111, Crop Production.
EPA compiled these identified NAICS codes in Table 2-70. EPA determined the number of workers
associated with each industry from U.S. Department of Agriculture (USD A) Census of Agriculture Data
(USDA 2014). The USDA conducts a census of agriculture instead of the US Census Bureau. Census of
agriculture data were available for 2012 and the number of farms and workers is summarized in Table
2-70. EPA did not find data on the number of workers and occupational non-users on a NAICS level.
Information on the total number of workers is available, but no information on the number of
occupational non-users was found in the census of agriculture.
The number of farms within each industry that use NMP-based fertilizers and the number of employees
at a farm exposed to these NMP-based products are unknown. Therefore, EPA provides the total number
of establishments and employees in these industries as bounding estimates of the number of
establishments that use and the number of employees that are potentially exposed to NMP-based
fertilizers. These bounding estimates are likely overestimates of the actual number of establishments and
employees potentially exposed to NMP during fertilizer application.
Table 2-70. U.S. Number of Establishments and
Employees for Fertilizer Application
2016
NAICS
2016 NAICS Title
Number of
Establishments
Number of
Workers
Sitea
Number of
ONUs per
Site8
1111
Oilseed and Grain Farming
369,332
NAICS specific data not
found
1112
Vegetable and Melon Farming
43,021
1113
Fruit and Tree Nut Farming
93,020
1114
Greenhouse, Nursery, and Floriculture Production
52,777
1119
Other Crop Farming
496,837
Total number of establishments, workers, and ONUs
potentially exposed b
1,100,000
1,300,000
Unknown
Sources: Number of establishments, workers per site, ONUs per site - (USDA. 2014)
a - EPA did not find data on the number of workers and occupational non-users on a NAICS level. EPA determined the
number of total workers for these NAICS codes by multiplying the total number of workers for all farms on the 2012 NAICS
by the fraction of farms that fall within the listed NAICS codes.
b - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.14.2.3 Occupational Exposure Assessment Methodology
2.14.2.3.1 Inhalation
EPA did not find inhalation monitoring data for the application of fertilizers containing NMP. The
RIVM Annex XV Proposal for a Restriction - NMP report presented the modeled potential inhalation
exposures during spray and fog application of agrochemicals (RIVM. 2013). EPA summarized these
modeled exposures in Appendix A. 14. Due to lack of additional information or modeling approaches,
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EPA uses the modeled exposures from the RIVM Annex XV Proposal for a Restriction - NMP report to
represent potential inhalation exposures during this scenario. These data are of acceptable quality.
The input parameters used for the PBPK modeling based on the modeled exposures are summarized in
Table 2-71. The RIVM Annex XF Proposal for a Restriction - NMP report recommends that manual
application activities should be limited to four hours per shift or less (RIVM. 2013). Application with
more automated equipment and separation of the worker from the sources of exposure can exceed this
recommendation. EPA thus assesses both full-shift 8-hour TWA and short-term 4-hour TWA inhalation
exposures. EPA did not find data on short-term exposures.
Table 2-71. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Fertilizer Application
Work Activity
Parameter
Characterization
Full-Shift NMP
Air Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Manual spray or
boom application
of fertilizers a
Low-end (of range)
2.97
No data
(RIVM.
2013)
High
High-end (of range)
5.27
No data
a - These data are from (RIVM. 2013) and are modeled exposures during the manual spray or boom application of
agrochemicals. No data on other forms of application were identified.
2.14.2.3.2 Dermal
Table 2-72 summarizes the parameters used to assess dermal exposure during the use of agricultural
products containing NMP. EPA assessed dermal exposure to NMP at the specified liquid weight
fraction, skin surface area, and exposure duration.
NMP Weight Fraction
As described in Section 2.14.1, the NMP Producers Group, Inc. indicated that NMP is present in
fertilizers in very small quantities, less than 0.1 weigh percent (Roberts. 2017). EPA identified multiple
other agricultural products from the 2017 market profile on NMP and the "Preliminary Information on
Manufacturing, Processing, Distribution, Use, and Disposal: NMP" document; however, these products
are all pesticides and other products that are not regulated under TSCA (Abt. 2017; U.S. EPA. 2017b).
EPA excludes those products from this risk evaluation. The RIVM Annex XV Proposal for a Restriction
- NMP report indicates that NMP is typically less than seven weight percent in agrochemical
formulations (RIVM. 2013). Due to lack of additional information, EPA assesses a low-end
concentration of 0.1 percent and a high-end concentration of seven percent. The underlying data used for
these estimates have overall confidence ratings of high.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. The PPE information described in Section 2.14.2.1 indicates that workers are likely to wear
gloves. EPA does not know the likelihood that workers wear gloves of the proper material and have
training on the proper usage of gloves. No information on employee training was found, but due to the
commercial nature of this use, EPA expects minimal to no employee training. Based on this information
EPA assesses a central tendency protection factor of 5 from Table 1-2 of Section 1.4.3.2.3. EPA also
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assesses that no gloves are used for a high-end exposure scenario, corresponding to a protection factor of
1 from Table 1-2 of Section 1.4.3.2.3. EPA did not find data on the use of gloves for this occupational
exposure scenario and the glove protection factor assumptions are based on professional judgment. The
assumed glove protection factor values are highly uncertain.
Exposure Duration
EPA did not find data on exposure duration. As described in Section 1.4.3.2.4, EPA assumes a high-end
exposure duration of eight hours and a central tendency exposure duration of four hours.
Table 2-72. Summary of Parameters for Worker Dermal Exposure During Fertilizer Application
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed b
Exposure
Duration
Body
Weight
b
Unitless
cm2
hr/day
kg
Manual spray or
boom application
of fertilizers a
Central Tendency
5
0.001
445 (f)
535 (m)
4
74 (f)
88 (m)
High-End
1
0.07
890 (f)
1,070 (m)
8
a These data are from (RIVM. 2013) and are modeled exposures during the manual spray or boom application of
agrochemicals. No data on other forms of application were identified.
b EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.14.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-73.
The numeric parameters corresponding to the characterizations presented in Table 2-73 are summarized
in Table 2-74. These are the inputs used in the PBPK model.
Table 2-73. Characterization of PBPK IV
odel Input Parameters for Fertilizer Application
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Characterization
Central
Tendency
Manual spray
or boom
application of
fertilizers
Low-end (of range)
Calculated 4-
hour TWA
from the 8-
hour TWA
data
1-hand
Yes
Central Tendency
High-end
Manual spray
or boom
application of
fertilizers
High-end (of range)
Based on 8-
hour TWA
data
2-hand
No
High-end
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Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
5.94
4
445 (f)
535 (m)
5
0.001
74 (f)
88 (m)
High-end
5.27
8
890 (f)
1,070 (m)
1
0.07
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
^.14.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.15Wood Preservatives
2.15.1 Process Description
The 2017 NMP market profile and the "Preliminary Information on Manufacturing, Processing,
Distribution, Use, and Disposal: NMP" document identify one product containing NMP that is used as a
wood preservative for in-service utility poles (Abt 2017; U.S. EPA 2017b). The physical state of this
product is a paste. Per the supplier, this product protects against decay and deterioration of wood
(https://www.osmose.com/documents/MP400-EXT%20product%20information%20bulletin.pdf).
Additionally, based on the physical form of the product and the description provided in the supplier's
information bulletin, EPA assesses application of this product as manual brushing or plastering onto
utility poles.
Because only one wood preservative product containing NMP was identified, this is likely a niche use of
NMP.
2.15.2 Exposure Assessment
2.15.2.1 Worker Activities
Workers are potentially exposed to NMP in wood preservative formulations during transferring of
formulations into smaller portable containers that can be taken out into the field to service utility poles.
During application of wood preservative pastes, EPA believes that workers are likely to manually apply
the wood preservatives using a large brush or trowel. These activities are both potential sources of
worker exposure through dermal contact, vapor-through-skin, and inhalation of NMP vapors.
EPA did not find information regarding the use of engineering controls or worker PPE during the use of
wood preservatives containing NMP. Because utility poles are located outdoors, EPA does not expect
the use of engineering controls during servicing of the utility poles. Utility workers generally wear hard
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hats, safety vests, and may wear work gloves. The use of respiratory protection is unknown but
considered unlikely.
Because the servicing of in-use utility poles typically occurs outdoors, along the sides of roads and other
outdoor areas that aren't typically occupied, EPA does not expect there to be ONUs nearby during the
use of wood preservatives for the servicing of existing utility poles. Thus, EPA does not assess potential
ONU exposure to NMP.
2.15.2.2 Number of Potentially Exposed Workers
Because the use of NMP in wood preservatives is a niche use, the only affected workers are likely to be
municipal utility workers. The utility industries are covered within the 3-digit NAICS code 221. Within
this NAICS group, EPA expects that the only NAICS codes that are likely to cover industries that
service utility poles are those within NAICS group 221120, Electric Power Transmission, Control, and
Distribution.
EPA compiled the associated NAICS codes for the identified industries in Table 2-75. EPA determined
the number of workers associated with each industry using Bureau of Labor Statistics' OES data (U.S.
BLS. 2016) and the U.S. Census' SUSB (U.S. Census Bureau. 2015). The number of establishments
within each industry that use NMP-based wood preservative products and the number of employees
within an establishment exposed to these NMP-based products are unknown. Therefore, EPA provides
the total number of establishments and employees in these industries as bounding estimates of the
number of establishments that use and the number of employees that are potentially exposed to NMP-
based wood preservative products. These bounding estimates are likely overestimates of the actual
number of establishments and employees potentially exposed to NMP during use of wood preservatives.
Table 2-75. US Number of Establishments and Employees for Industries Using Wood
Preservatives
Industry
2016
NAICS
2016 NAICS Title
Number of
Establishments
Number
of
Workers
Site a
Number
of ONUs
per Site
b
Utilities
221121
Electric Bulk Power Transmission
and Control
268
49
0
221122
Electric Power Distribution
7487
48
0
Total number of establishments, workers, and ONUs
potentially exposedc
7,800
380,000
0
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest worker. No 2016 BLS data found for this NAICS. EPA determined number of workers per site by
dividing the total number of employees by the total number of establishments from SUSB data.
b - No 2016 BLS data found for this NAICS. EPA does not expect ONUs to be affected during outdoor utility pole servicing,
c - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.15.2.3 Occupational Exposure Assessment Methodology
2.15.2.3.1 Inhalation
Appendix A. 15 summarizes the inhalation monitoring data and modeled exposure data for NMP-based
wood preservative application. Due to limited relevance and quality of monitoring data and modeling
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estimates for application of wood preservatives found in the published literature, EPA used modeling
estimates with the highest data quality for this use, as described further below.
The summarized monitoring data does not include worker activities which EPA expects to occur within
this scenario. Thus, EPA uses a modeled exposure for the brush application of a substance containing
NMP that was presented in the RIVM Annex XV Proposal for a Restriction - NMP report. Additional
details on EPA's rationale for inclusion or exclusion of these data in the risk evaluation are included in
Appendix A. 15.
The modeled exposure from brush application is summarized into the input parameters used for the
PBPK modeling in Table 2-76. EPA did not find data on short-term exposures for this scenario.
Note that EPA does not expect there to be ONUs nearby during the use of wood preservatives for the
servicing of existing utility poles. Thus, EPA does not assess potential ONU exposure to NMP.
Table 2-76. Summary of Parameters for Wood Preservatives
Work
Activity
Parameter
Characterization
Full-Shift NMP Air
Concentration
Duration-Based NMP
Air Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Brush
Application
Single estimate
4.13
No data
(RIVM.
2013)
High
2.15.2.3.2 Dermal
Table 2-77 summarizes the parameters used to assess dermal exposure during the use of wood
preservatives containing NMP. EPA assessed dermal exposure to NMP at the specified liquid weight
fraction, skin surface area, and exposure duration.
NMP Weight Fraction
The 2017 market profile for NMP (Abt 2017) and the "Preliminary Information on Manufacturing,
Processing, Distribution, Use, and Disposal: NMP" document (U.S. EPA 2017b) identified one wood
preservative product containing NMP. The SDS for this product indicates NMP is present in the
formulation at less than one percent. Due to lack of additional information, EPA assesses a weight
fraction of one percent.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. EPA did not find information on the use of gloves. Thus, EPA assesses that no gloves are used
for the high-end exposure scenario, corresponding to a protection factor of 1 from Table 1-2 of Section
1.4.3.2.3. EPA expects that workers may potentially wear gloves but does not know the likelihood that
workers wear gloves of the proper material and have training on the proper usage of gloves. No
information on employee training was found, but due to the commercial nature of this use, EPA expects
minimal to no employee training. Based on this information EPA assesses a central tendency protection
factor of 5 from Table 1-2 of Section 1.4.3.2.3. EPA did not find data on the use of gloves for this
occupational exposure scenario and the glove protection factor assumptions are based on professional
judgment. The assumed glove protection factor values are highly uncertain.
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Exposure Duration
EPA did not find data on exposure duration. As described in Section 1.4.3.2.4, EPA assumes a high-end
exposure duration of eight hours and a central tendency exposure duration of four hours.
Table 2-77. Summary of Parameters for Worker Dermal Exposure to Wood Preservatives
Work
Activity
Parameter
Characterization
Glove
Protection
Factor (s)
NMP
Weight
Fraction
Skin Surface
Area Exposed
a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Brush
Application
Central Tendency
5
0.01
445 (f)
535 (m)
4
74 (f)
88 (m)
High-End
1
0.01
890 (f)
1,070 (m)
8
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.15.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-78.
The numeric parameters corresponding to the characterizations presented in Table 2-78 are summarized
in Table 2-79. These are the inputs used in the PBPK model.
Table 2-78. Characterization of PBPK Model Input Parameters for Wood Preservatives
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Ch ar acteriz ation
Central
Tendency
Brush
application
Single estimate
Assumed 4
hours
1-hand
Yes
Single data point
available and used for
both exposure
scenarios
High-end
Brush
application
Single estimate
Assumed 8
hours
2-hand
No
Single data point
available and used for
both exposure
scenarios
Table 2-79. PBPK Model Input Parameters for Wood Preservatives
Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg) b
Central Tendency
8.26
4
445 (f)
535 (m)
5
0.01
74 (f)
88 (m)
High-end
4.13
8
890 (f)
1,070 (m)
1
0.01
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
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bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
2,15,4^ Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
2.16 Recycling and Disposal
2.16.1 Process Description
Each of the conditions of use of NMP may generate waste streams of the chemical that are collected and
transported to third-party sites for disposal, treatment, or recycling. Industrial sites that treat or dispose
onsite wastes that they themselves generate are likely for chemical processing sites (excluding
formulation) and are assessed in Section 2.3. Wastes of NMP that are generated during a scenario and
sent to a third-party site for treatment, disposal, or recycling may include the following:
• Wastewater: NMP may be contained in wastewater discharged to POTW or other, non-public
treatment works for treatment. Industrial wastewater containing NMP discharged to a POTW
may be subject to EPA or authorized NPDES state pretreatment programs.
• Solid Wastes: Solid wastes are defined under RCRA as any material that is discarded by being:
abandoned; inherently waste-like; a discarded military munition; or recycled in certain ways
(certain instances of the generation and legitimate reclamation of secondary materials are
exempted as solid wastes under RCRA). Solid wastes may subsequently meet RCRA's definition
of hazardous waste by either being listed as a waste at 40 CFR §§ 261.30 to 261.35 or by
meeting waste-like characteristics as defined at 40 CFR §§ 261.20 to 261.24. Solid wastes that
are hazardous wastes are regulated under the more stringent requirements of Subtitle C of
RCRA, whereas non-hazardous solid wastes are regulated under the less stringent requirements
of Subtitle D of RCRA.
o NMP is not designated as a hazardous substance under federal regulations. However,
three states, Massachusetts, New Jersey and Pennsylvania have designated NMP as a
hazardous substance, thereby regulating NMP disposal ( )18c). The 2016 TRI
results indicate multiple sites reported releases to RCRA Subtitle C Landfills (
2016b).
• Wastes Exempted as Solid Wastes under RCRA: Certain conditions of use of NMP may generate
wastes of NMP that are exempted as solid wastes under 40 CFR § 261.4(a). For example, the
generation and legitimate reclamation of hazardous secondary materials of NMP may be exempt
as a solid waste.
2016 TRI data lists off-site transfers of NMP to land disposal, wastewater treatment, incineration,
recycling facilities, and other off-site transfers. About 51% of off-site transfers were recycled off-site,
26% were incinerated, 12% were sent to land disposal, 7% were sent to wastewater treatment, and 5%
were disposed of via other off-site transfers ( ). See Figure 2-4 for a diagram of a typical
waste disposal process.
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Recycling
Hazardous Waste Hazardous Waste
Generation Transportation
Treatment
CSS
_ Disposal
Figure 2-4. Typical Waste Disposal Process (J.S, EPA, 2017a)
Municipal Waste Incineration
Municipal waste combustors (MWCs) that recover energy are generally located at large facilities
comprising an enclosed tipping floor and a deep waste storage pit. Typical large MWCs may range in
capacity from 250 to over 1,000 tons per day. At facilities of this scale, waste materials are not generally
handled directly by workers. Trucks may dump the waste directly into the pit, or waste may be tipped to
the floor and later pushed into the pit by a worker operating a front-end loader. A large grapple from an
overhead crane is used to grab waste from the pit and drop it into a hopper, where hydraulic rams feed
the material continuously into the combustion unit at a controlled rate. The crane operator also uses the
grapple to mix the waste within the pit, in order to provide a fuel consistent in composition and heating
value, and to pick out hazardous or problematic waste.
Facilities burning refuse-derived fuel (RDF) conduct on-site sorting, shredding, and inspection of the
waste prior to incineration to recover recyclables and remove hazardous waste or other unwanted
materials. Sorting is usually an automated process that uses mechanical separation methods, such as
trommel screens, disk screens, and magnetic separators. Once processed, the waste material may be
transferred to a storage pit, or it may be conveyed directly to the hopper for combustion.
Tipping floor operations may generate dust. Air from the enclosed tipping floor, however, is
continuously drawn into the combustion unit via one or more forced air fans to serve as the primary
combustion air and minimize odors. Dust and lint present in the air is typically captured in filters or
other cleaning devices in order to prevent the clogging of steam coils, which are used to heat the
combustion air and help dry higher-moisture inputs (Kitto. 1992).
Hazardous Waste Incineration
Commercial scale hazardous waste incinerators are generally two-chamber units, a rotary kiln followed
by an afterburner, that accept both solid and liquid waste. Liquid wastes are pumped through pipes and
are fed to the unit through nozzles that atomize the liquid for optimal combustion. Solids may be fed to
the kiln as loose solids gravity fed to a hopper, or in drums or containers using a conveyor (ETC, 2018;
r'T ifSai
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Heritage. 2018).
Incoming hazardous waste is usually received by truck or rail, and an inspection is required for all waste
received. Receiving areas for liquid waste generally consist of a docking area, pumphouse, and some
kind of storage facilities. For solids, conveyor devices are typically used to transport incoming waste
(ETC. 2018; Heritage. 2018V
Smaller scale units that burn municipal solid waste or hazardous waste (such as infectious and hazardous
waste incinerators at hospitals) may require more direct handling of the materials by facility personnel.
Units that are batch-loaded require the waste to be placed on the grate prior to operation and may
involve manually dumping waste from a container or shoveling waste from a container onto the grate.
A typical industrial incineration process is depicted in Figure 2-5 below.
Emissions Stack
Scrubber Water or
Ash Handling
Feed Preparation
Heat Recovery
Gas Temperature
Reduction
Combustion
Ash Handling
Waste Storage
Air Pollution Control
Disposal Disposal
Figure 2-5. Typical Industrial Incineration Process
Municipal Waste Landfill
Municipal solid waste landfills are discrete areas of land or excavated sites that receive household
wastes and other types of non-hazardous wastes (e.g. industrial and commercial solid wastes). Standards
and requirements for municipal waste landfills include location restrictions, composite liner
requirements, leachate collection and removal system, operating practices, groundwater monitoring
requirements, closure-and post-closure care requirements, corrective action provisions, and financial
assurance. Non-hazardous solid wastes are regulated under RCRA Subtitle D, but states may impose
more stringent requirements.
Municipal solid wastes may be first unloaded at waste transfer stations for temporary storage, prior to
being transported to the landfill or other treatment or disposal facilities.
Hazardous Waste Landfill
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Hazardous waste landfills are excavated or engineered sites specifically designed for the final disposal
of non-liquid hazardous wastes. Design standards for these landfills require double liner, double leachate
collection and removal systems, leak detection system, run on, runoff and wind dispersal controls, and
construction quality assurance program ( 2018b). There are also requirements for closure and
post-closure, such as the addition of a final cover over the landfill and continued monitoring and
maintenance. These standards and requirements prevent potential contamination of groundwater and
nearby surface water resources. Hazardous waste landfills are regulated under Part 264/265, Subpart N.
According to 2016 TRI data, a large portion of land releases are to landfills other than RCRA Subtitle C
hazardous waste landfills. Approximately 150,000 pounds of NMP were reportedly released RCRA
Subtitle C hazardous waste landfills, while 2.4 million pounds of NMP were reported to other landfills
(U.S. EPA. 2016b). EPA expects that NMP wastes sent to municipal landfills are likely to be consumer
and commercial wastes with low potential for NMP to be available for exposure. For example, NMP in
used aerosol cans, paint and coating containers, and other containers that held NMP formulations.
Recycling
Waste NMP solvent is generated when it becomes contaminated with suspended and dissolved solids,
organics, water, or other substances ( 0). Waste solvents can be restored to a condition that
permits reuse via solvent reclamation/recycling ( 85, 1980). Waste NMP is shipped to a
solvent recovery site where it is piped or manually loaded into process equipment ( >)•
The waste solvent then undergoes a vapor recovery (e.g., condensation, adsorption and absorption) or
mechanical separation (e.g., decanting, filtering, draining, setline and centrifuging) step followed by
distillation, purification and final packaging (UJ 85, 1980).
2.16.2 Exposure Assessment
2.16.2.1 Worker Activities
EPA assumes that any exposures related to on-site waste treatment and disposal are addressed in the
assessments for those uses in this report; therefore, this section assesses exposures to workers for wastes
transferred from the use site to an off-site waste treatment and disposal facility. At waste disposal sites,
workers are potentially exposed via dermal contact with waste containing NMP or via inhalation of
NMP vapor. Depending on the concentration of NMP in the waste stream, the route and level of
exposure may be similar to that associated with container unloading activities.
ONUs include employees that work disposal and recycling sites, but they do not directly handle the
chemical and are therefore expected to have lower inhalation exposures and vapor-through-skin uptake
and are not expected to have dermal exposures by contact with liquids. ONUs for disposal and recycling
sites include supervisors, managers, and tradesmen that may be in the processing and disposal area but
do not perform tasks that result in the same level of exposures as workers that directly handle NMP
wastes.
Municipal Waste Incineration
At municipal waste incineration facilities, there may be one or more technicians present on the tipping
floor to oversee operations, direct trucks, inspect incoming waste, or perform other tasks as warranted by
individual facility practices. These workers may wear protective gear such as gloves, safety glasses, or
dust masks. Specific worker protocols are largely up to individual companies, although state or local
regulations may require certain worker safety standards be met. Federal operator training requirements
pertain more to the operation of the regulated combustion unit rather than operator health and safety.
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Workers are potentially exposed via inhalation to vapors while working on the tipping floor. Potentially-
exposed workers include workers stationed on the tipping floor, including front-end loader and crane
operators, as well as truck drivers. The potential for dermal exposures is minimized by the use of trucks
and cranes to handle the wastes.
Hazardous Waste Incineration
More information is needed to determine the potential for worker exposures during hazardous waste
incineration and any requirements for personal protective equipment. There is likely a greater potential
for worker exposures for smaller scale incinerators that involve more direct handling of the wastes.
Municipal and Hazardous Waste Landfill
At landfills, typical worker activities may include operating refuse vehicles to weigh and unload the
waste materials, operating bulldozers to spread and compact wastes, and monitoring, inspecting, and
surveying and landfill site (CalRecvcle. 2018).
2.16.2.2 Number of Potentially Exposed Workers
As discussed in Section 2.16.1, NMP may be disposed of as hazardous waste at TSDFs, recycled, or
disposed of as municipal waste in used commercial and consumer articles. These operations are covered
by the NAICS codes EPA compiled in Table 2-80. EPA determined the number of workers associated
with each industry identified using Bureau of Labor Statistics' OES data (U.S. BLS. 2016) and the U.S.
Census' SUSB (U.S. Census Bureau. 2015). EPA also searched available 2016 TRI NMP data for the
each NAICS code. The 2016 TRI results indicate that there are 22 sites with operations covered by
NAICS 562211 and two sites with operations covered by NAICS 562920 reporting NMP releases.
The total number of sites that treat and dispose wastes containing NMP is not known. It is possible that
additional hazardous waste treatment facilities treat and dispose NMP but do not meet the TRI reporting
threshold for reporting year 2016. In addition, it is possible that some consumer products containing
NMP may be improperly disposed as municipal solid wastes, and that some amount of NMP is present
in non-hazardous waste streams. Therefore, the total number of workers and ONUs potentially exposed
to NMP may exceed those estimates presented in Table 2-80.
Table 2-80. US Number of Establishments and Employees for Recycling
and Disposal
Industry
2016
NAICS
2016 NAICS Title
Number of
Establishments
per 2016 TRI
Number
of
Workers
per Site
per BLS
Data a
Number
of
ONUs
per Site
per
BLS
Data a
Hazardous waste
disposal and recycling
562211
Hazardous Waste Treatment and
Disposal
22
9
5
Non-hazardous waste
disposal
562212
Solid Waste Landfill
0
3
2
562213
Solid Waste Combustors and
Incinerators
0
13
8
562219
Other Nonhazardous Waste
Treatment and Disposal
0
3
2
Other materials
recovery
562920
Materials Recovery Facilities
2
2
2
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2016
NAICS
Number of
Number
of
Workers
per Site
per BLS
Data a
Number
of
ONUs
Industry
2016 NAICS Title
Establishments
per 2016 TRI
per Site
per
BLS
Data a
Total number of establishments, workers, and ONUs potentially
exposedc
24
200
120
Sources: Number of establishments, workers per site, ONUs per site - (U.S. BLS. 2016: U.S. Census Bureau. 2015)
a - Rounded to the nearest worker.
b - Unrounded figures were used for total worker and ONU calculations. Totals may not add exactly due to rounding to two
significant figures.
2.16.2.3 Occupational Exposure Assessment Methodology
2.16.2.3.1 Inhalation
EPA did not find monitoring data on the handling of NMP wastes at disposal and recycling sites. EPA
therefore compiled the same monitoring and modeled exposure concentration data for this scenario as
that for manufacturing. These data are summarized in Appendix A. 1. As described for Manufacturing in
Section 2.1.2.3.1, due to limited relevance and quality of monitoring data and modeling estimates found
in the published literature, EPA used modeling estimates with the highest data quality for this use, as
further described below.
EPA only found one source with monitoring data on the storing and conveying of NMP, which did not
include details on worker activities, sample locations, or sampling times. EPA also summarized in
Appendix A. 16 the modeled inhalation exposure concentrations during the manufacturing of NMP, for
closed- and open-system transfers of NMP, that were presented in the RIVM Annex XV Proposal for a
Restriction - NMP report (RIVM. 2013).
Consistent with the approach EPA took in Section 2.1.2.3.1 for the manufacture of NMP, EPA modeled
potential worker inhalation exposures during the unloading of bulk storage containers and drums using
EPA models. EPA's modeled exposure concentrations represent a larger range of potential inhalation
exposure concentrations than those presented by RIVM; thus, EPA uses these modeled exposures in lieu
of using the monitoring data or modeled exposure in the RIVM Annex XV Proposal for a Restriction -
NMP report. The inhalation monitoring data as well as the RIVM and EPA's modeled exposure
concentrations are summarized and further explained in Appendix A. 16.
The inhalation exposure concentrations modeled by EPA for unloading of 100% NMP are summarized
into the input parameters used for the PBPK modeling in Table 2-81. The container unloading models
used by EPA calculate short-term exposure concentrations, with the exposure duration equal to the
duration of the unloading event (for bulk containers, typical case is 0.5 hours for unloading tank trucks
and worst-case is 1 hour for unloading rail cars; for drums, 20 containers are unloaded per hour and the
duration was determined based on the throughput of NMP at a site [refer to Appendix A. 16 for further
explanation]) and number of unloading events per day. EPA calculated the 8-hour TWA exposures to as
the weighted average exposure during an entire 8-hour shift, assuming zero exposures during the
remainder of the shift.
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The Tank Truck and Railcar Loading and Unloading Release and Inhalation Exposure Model involves
deterministic modeling and the Drum Loading and Unloading Release and Inhalation Exposure Model
involves probabilistic modeling. See Appendix B.2 and B.3 for additional details on the bulk container
loading modeling and the drum loading modeling, respectively.
Table 2-81. Summary of Parameters for PBPK Modeling of Worker Inhalation Exposure During
Recycling and Disposal
Work
Activity
Parameter
Characterization
Full-Shift NMP
Air
Concentration
Duration-Based
NMP Air
Concentration
Source
Data
Quality
Rating
(mg/m3, 8-hour
TWA)
(mg/m3)
Unloading
bulk
containers
Central tendency
(50th percentile)
0.048
0.760 (duration =
0.5 hr)
Tank Truck and
Railcar Loading and
Unloading Release
and Inhalation
Exposure Model
(U.S. EPA. 2013a)
Not
applicable3
High-end (95th
percentile)
0.190
1.52 (duration = 1
hr)
Unloading
drums
Central tendency
(50th percentile)
0.125
1.65 (duration =
0.603 hr)
Drum Loading and
Unloading Release
and Inhalation
Exposure Model
(U.S. EPA. 2013a)
Not
applicable3
High-end (95th
percentile)
0.441
5.85 (duration =
0.603 hr)
a - EPA models are standard sources used by RAD for engineering assessments. EPA did not systematically review models
that were developed by EPA.
2.16.2.3.2 Dermal
Table 2-82 summarizes the parameters used to assess dermal exposure during worker handling of wastes
containing NMP. EPA assesses dermal exposure to NMP at the specified liquid weight fraction, skin
surface area, and exposure duration, based on the methodology described below. During this scenario,
workers are potentially exposed during unloading and loading activities, waste sorting activities, and
equipment maintenance. For this scenario, EPA assessed dermal exposures during the unloading of pure
NMP from bulk containers and drums. See below for additional information.
NMP Weight Fraction
EPA found limited information on the concentration of NMP in waste solvents to be recycled and
industrial and commercial wastes containing NMP. The data submitted by SIA for the use of NMP in the
production of semiconductors (discussed in Section 2.8.2) include one inhalation monitoring data point
for the loading of trucks with waste NMP. This data point indicates that NMP is 92% in the handled
waste material (SIA 2019b). EPA uses this concentration for the central tendency NMP weight fraction.
Due to lack of information on the concentration of NMP in waste solvents, for the high-end NMP
concentration value, EPA expects that waste NMP may contain very little impurities and be up to 100
weight percent NMP.
Skin Surface Area and Glove Usage
As described in Section 1.4.3.2.2, EPA assessed high-end skin surface areas of 890 cm2 for females and
1,070 cm2 for males and central tendency skin surface areas of 445 cm2 for females and 535 cm2 for
males. As discussed in Section 2.16.2.1, EPA did not find information regarding the use of PPE for this
scenario. EPA expects that workers may potentially wear gloves but does not know the likelihood that
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workers wear gloves of the proper material and have training on the proper usage of gloves. No
information on employee training was found. Because solvent recycling activities likely occur at
industrial sites, but are not highly controlled in nature, EPA expects that employees may have basic
training, corresponding to a protection factor of 10 from Table 1-2 of Section 1.4.3.2.3. As EPA expects
this is the most likely scenario, EPA uses a glove protection factor of 10 for both the central tendency
and high-end scenarios. EPA did not find data on the use of gloves for this occupational exposure
scenario and the glove protection factor assumptions are based on professional judgment. The assumed
glove protection factor values are highly uncertain.
Exposure Duration
EPA did not find data on exposure duration. As described in Section 1.4.3.2.4, EPA assumes a high-end
exposure duration of eight hours and a central tendency exposure duration of four hours.
Table 2-82. Summary of Parameters for Worker Dermal Exposure During Recycling and Disposal
Work Activity
Parameter
Characterization
Glove
Protection
Factor(s)
NMP
Weight
Fraction
Skin Surface
Area
Exposed a
Exposure
Duration
Body
Weighta
Unitless
cm2
hr/day
kg
Unloading bulk
containers;
Unloading drums
Central Tendency
10
0.92
445 (f)
535 (m)
4
74 (f)
High-End
10
1
890 (f)
1,070 (m)
8
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
2.16.3 PBPK Inputs
Based on the methodology described in the previous sections, EPA assessed PBPK parameters for
central tendency and high-end exposure scenarios based on the characterizations listed in Table 2-83.
The numeric parameters corresponding to the characterizations presented in Table 2-83 are summarized
in Table 2-84. These are the inputs used in the PBPK model.
Table 2-83. Characterization of PBPK Model Input Parameters for Recycle and Disposal
Scenario
Work
Activity
Air Concentration
Data
Characterization
Exposure
Duration
Skin
Surface
Area
Exposed
Gloves
NMP Weight
Fraction
Ch ar acteriz ation
Central
Tendency
Unloading
bulk
containers
Central tendency
(50th percentile)
Duration
calculated
by model
1-hand
Yes
Central tendency
High-end
Unloading
drums
High-end (95th
percentile)
Duration
calculated
by model
2-hand
Yes
High-end
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Table 2-84. PBPK Model Input Parameters for Recycle and Disposal
Scenario
Duration-Based
NMP Air
Concentration
(mg/m3)
Exposure
Duration
(hr)
Skin
Surface
Area
Exposed
(cm2) a'b
Gloves
Protection
Factor
NMP
Weight
Fraction
Body
Weight
(kg)a
Central Tendency
0.760
0.5
445 (f)
535 (m)
10
0.92
74 (f)
88 (m)
High-end
5.85
0.603
890 (f)
1,070 (m)
10
1
74 (f)
88 (m)
a EPA assessed these exposure factors for both females and males. Values associated with females are denoted with (f) and
values associated with males are denoted with (m).
bEPA assessed a skin surface area exposed of 0.1 cm2for ONUs for each scenario. However, EPA did not assess glove usage
(protection factor = 1) for ONUs.
^.16.4 Summary
In summary, dermal exposure and inhalation are expected for this use. EPA has not identified additional
uncertainties for this use beyond those included in Section 3.
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3 Discussion of Results
3.1 Variability
EPA addressed variability in models by identifying key model parameters to apply a statistical
distribution that mathematically defines the parameter's variability. EPA defined statistical distributions
for parameters using documented statistical variations where available.
3.2 Uncertainties and Limitations
Uncertainty is "the lack of knowledge about specific variables, parameters, models, or other factors" and
can be described qualitatively or quantitatively (U.S. EPA, 2001). The following sections discuss
uncertainties in each of the assessed NMP use scenarios.
3.2.1 Number of Workers
There are a number of uncertainties surrounding the estimated number of workers potentially exposed to
NMP, as outlined below.
First, BLS' OES employment data for each industry/occupation combination are only available at the 3-,
4-, or 5-digit NAICS level, rather than the full 6-digit NAICS level. This lack of granularity could result
in an overestimate of the number of exposed workers if some 6-digit NAICS are included in the less
granular BLS estimates but are not, in reality, likely to use NMP for the assessed applications. EPA
addressed this issue by refining the OES estimates using total employment data from the U.S. Census'
SUSB. However, this approach assumes that the distribution of occupation types (SOC codes) in each 6-
digit NAICS is equal to the distribution of occupation types at the parent 5-digit NAICS level. If the
distribution of workers in occupations with NMP exposure differs from the overall distribution of
workers in each NAICS, then this approach will result in inaccuracy. The effects of this uncertainty on
the number of worker estimates are unknown, as the uncertainties may result in either over or
underestimation of the estimates depending on the actual distribution.
Second, EPA's judgments about which industries (represented by NAICS codes) and occupations
(represented by SOC codes) are associated with the uses assessed in this report are based on EPA's
understanding of how NMP is used in each industry. Designations of which industries and occupations
have potential exposures is nevertheless subjective, and some industries/occupations with few exposures
might erroneously be included, or some industries/occupations with exposures might erroneously be
excluded. This would result in inaccuracy but would be unlikely to systematically either overestimate or
underestimate the count of exposed workers.
3.2.2 PBPK Input Parameters
Key uncertainties in the occupational exposure parameters are summarized below. Most parameters are
related specifically to the route of dermal contact with liquids by workers, while air concentrations are
related to the routes of inhalation and vapor-through-skin exposure. The body weight parameter is
related to all of these routes. The assumed values for human body weight have relatively lower
uncertainties, and the median values used may underestimate exposures at the high-end of PBPK
exposure results.
The dermal exposure parameters used in this assessment have uncertainties because many parameters
lack data and were therefore based on assumptions. The assumed parameter values with the greatest
uncertainties are glove use and effectiveness (using protection factors based on the ECETOC TRA
model that are what-if type values as described in Section 1.4.3.2.3), durations of contact with liquid,
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and skin surface areas for contact with liquids. The assumed values for effectiveness, durations of
contact, and surface areas for contact may or may not be representative of actual values. The assumed
values for NMP concentrations in formulations have relatively lower uncertainties. The midpoints of
some ranges serve as substitutes for 50th percentiles of the actual distributions and high ends of ranges
serve as substitutes for 95th percentiles of the actual distributions. However, these substitutes are
uncertain and are weak substitutes for the ideal percentile values. Generally, EPA cannot determine
whether most of these assumptions may overestimate or underestimate exposures. However, high-end
duration of dermal contact estimates of 8 hours may be more likely to overestimate exposure potential to
some extent, and some activity-based durations may be more likely to underestimate exposure potential
to some extent. For many OESs, the high-end surface area assumption of contact over the full area of
two hands likely overestimates exposures. Occupational non-users (ONUs) may have direct contact with
NMP-based liquid products due to incidental exposure at shared work areas with workers who directly
work with NMP, and the estimate of zero surface area contact may underestimate their exposure. The
parameter values NMP concentrations are from available data and are likely to have a relatively low
impact on the magnitude (less than an order of magnitude, or factor of 10) of overestimation or
underestimation of exposure. The impact of vapors being trapped next to the skin during glove use is
also uncertain.
Where monitoring data are available, limitations of the data also introduce uncertainties into the
exposures. The principal limitation of the air concentration data is the uncertainty in the
representativeness of the data. EPA identified a limited number of exposure studies and data sets that
provided data for facilities or job sites where NMP was used. Some of these studies primarily focused on
single sites. This small sample pool introduces uncertainty as it is unclear how representative the data
for a specific end use are for all sites and all workers across the US. Differences in work practices and
engineering controls across sites can introduce variability and limit the representativeness of any one site
relative to all sites. Age of the monitoring data can also introduce uncertainty due to differences in work
practices and equipment used at the time the monitoring data were taken and those used currently, so the
use of older data may over- or underestimate exposures. Additionally, some data sources may be
inherently biased. For example, bias may be present if exposure monitoring was conducted to address
concerns regarding adverse human health effects reported following exposures during use. The effects of
these uncertainties on the occupational exposure assessment are unknown, as the uncertainties may
result in either over or underestimation of exposures depending on the actual distribution of inhalation
exposure concentrations and the variability of work practices among different sites.
The impact of these uncertainties precluded EPA from describing actual parameter distributions. In most
scenarios where data were available, EPA did not find enough data to determine complete statistical
distributions. Ideally, EPA would like to know 50th and 95th percentiles for each exposed population. In
the absence of percentile data for monitoring, the means or midpoint of the range serve as substitutes for
50th percentiles of the actual distributions and high ends of ranges serve as substitutes for 95th
percentiles of the actual distributions. However, these substitutes are uncertain and are weak substitutes
for the ideal percentile values. The effects of these substitutes on the occupational exposure assessment
are unknown, as the substitutes may result in either over or underestimation of exposures depending on
the actual distribution.
Where data were not available, the modeling approaches used to estimate air concentrations also have
uncertainties. Parameter values used in models did not all have distributions known to represent the
modeled scenario. It is also uncertain whether the model equations generate results that represent actual
workplace air concentrations. Some activity-based modeling does not account for exposures from other
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activities. Additional model-specific uncertainties are included below. In general, unless specified
otherwise, the effects of the below model-specific uncertainties on the exposure estimates are unknown,
as the uncertainties may result in either over or underestimation on exposures depending on the actual
distributions of each of the model input parameters.
3.2.2.1 Tank Truck and Railcar Loading and Unloading Release and Inhalation
Exposure Model
For manufacturing; repackaging; and recycling and disposal, the Tank Truck and Railcar Loading and
Unloading Release and Inhalation Exposure Model was used to estimate the airborne concentration
associated with generic chemical loading scenarios at industrial facilities. Specific uncertainties
associated with this model are described below:
• After each loading event, the model assumes saturated air containing NMP that remains in the
transfer hose and/or loading arm is released to air. The model calculates the quantity of saturated
air using design dimensions of loading systems published in the OPW Engineered Systems
catalog and engineering judgment. These dimensions may not be representative of the whole
range of loading equipment used at industrial facilities handling NMP.
• The model estimates fugitive emissions from equipment leaks using total organic compound
emission factors from EPA's Protocol for Equipment Leak Emission Estimates (U.S. EPA.
1995). and engineering judgement on the likely equipment type used for transfer (e.g. number of
valves, seals, lines, and connections). The applicability of these emission factors to NMP, and
the accuracy of EPA's assumption on equipment type are not known.
3.2.2.2 Drum Loading and Unloading Release and Inhalation Exposure Model
For chemical processing, excluding formulation and incorporation into formulation, mixture, or reaction
product, the Drum Loading and Unloading Release and Inhalation Exposure Model was used to
estimate the airborne concentration associated with generic chemical loading scenarios at industrial
facilities. Specific uncertainties associated with this model are described below:
• The model estimates fugitive emissions using the EPA/OAQPS AP-42 Loading Model. The
applicability of the emission factors used in this model to NMP is not known.
• EPA assigned statistical distributions based on available literature data or engineering judgment
to address the variability in Ventilation Rate (Q), Mixing Factor (k), Vapor Saturation Factor (f),
and Exposed Working Years per Lifetime (WY). The selected distributions may vary from the
actual distributions.
3.2.2.3 Model for Occupational Exposures during Aerosol Degreasing of Automotive
Brakes
The aerosol degreasing assessment uses a near-field/far-field approach (uncertainties on this approach
are presented below) to model worker exposure. Specific uncertainties associated with the aerosol
degreasing scenario are presented below:
• The model references a CARB study (GARB. 2000) on brake servicing to estimate use rate and
application frequency of the degreasing product. The brake servicing scenario may not be
representative of the use rates for other aerosol degreasing applications involving NMP;
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• Aerosol formulations were taken from available safety data sheets, and some were provided as
ranges. For each Monte Carlo iteration the model selects an NMP concentration within the range
of concentrations using a uniform distribution. In reality, the NMP concentration in the
formulation may be more consistent than the range provided.
3.2.2.4 Near-Field/Far-Field Model Framework
The near-field/far-field approach is used as a framework to model inhalation exposure for aerosol
degreasing. The following describe uncertainties and simplifying assumptions generally associated with
this modeling approach:
• There is some degree of uncertainty associated with each model input parameter. In general, the
model inputs were determined based on review of available literature. Where the distribution of
the input parameter is known, a distribution is assigned to capture uncertainty in the Monte Carlo
analysis. Where the distribution is unknown, a uniform distribution is often used. The use of a
uniform distribution will capture the low-end and high-end values but may not accurately reflect
actual distribution of the input parameters.
• The model assumes the near-field and far-field are well mixed, such that each zone can be
approximated by a single, average concentration.
• All emissions from the facility are assumed to enter the near-field. This assumption will
overestimate exposures and risks in facilities where some emissions do not enter the airspaces
relevant to worker exposure modeling.
• The exposure models estimate airborne concentrations. Exposures are calculated by assuming
workers spend the entire activity duration in their respective exposure zones (i.e., the worker in
the near-field and the occupational non-user in the far-field). A worker may actually walk away
from the near-field during part of the process. As such, assuming the worker is exposed at the
near-field concentration for the entire activity duration may overestimate exposure.
• The exposure models represent model workplace settings for NMP used in aerosol degreasing of
automotive brakes. The model has not been regressed or fitted with monitoring data.
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APPENDICES
Appendix A Inhalation Data for Each Occupational Scenario
This appendix summarizes the personal monitoring data EPA found for each scenario, as well as EPA's
rationale for inclusion or exclusion in the risk evaluation.
A.l Manufacturing
Limited monitoring data for the manufacture of NMP are available based on the information searched at
the time of preparation of this report. Two data points for the storing and conveying of NMP were
included in a compilation of NMP monitoring data prepared by the German Institute for Occupational
Safety and Health (IFA) ( 10). These data are summarized in Rows 1 and 2 of Table Apx A-l.
However, the associated worker activities, sampling areas, sampling times, and type of storing and
conveying systems associated with these data are unknown. EPA therefore excluded these data points
from this analysis.
In addition to this monitoring data, EPA identified modeled potential inhalation exposures during
manufacturing of NMP that were included in the RIVM Annex XV Proposal for a Restriction - NMP
report (RIVM. 2013). These modeled exposures are presented in Rows 3 through 12. Rows 3 through 5
are for closed-system transfers of NMP, with various degrees of control of the system (i.e., the system in
Row 3 is the most well-controlled, while the system in Row 5 is the least controlled closed system).
RIVM modeled and assessed potential inhalation exposures during manufacturing for each of these three
modeled scenarios of system control levels. The report indicated closed-system transfers are likely for
manufacturing of NMP.
In addition to these closed systems, RIVM included modeled exposures for the transfer of NMP in open
systems, which the report assesses for conditions of use other than manufacturing (as closed systems are
assumed for manufacturing). These modeled exposures are presented in Rows 6 through 12 of
Table Apx A-l. EPA excludes those points that describe commercial operations, as manufacturing of
NMP is expected to be an industrial process.
EPA modeled potential worker inhalation exposures during the loading of bulk storage containers (i.e.,
tank trucks and rail cars) and drums with pure NMP using common loading models developed by EPA,
to compare to the RIVM modeled exposures. The loading activity during manufacture is expected to
present the highest potential for worker exposure during a shift. EPA assumes NMP is loaded into
transport containers and distributed in bulk as a pure substance (100 percent concentration).
For the loading of bulk containers with NMP, EPA developed the Tank Truck and Railcar Loading and
Unloading Release and Inhalation Exposure Model, which calculates potential exposure concentrations
based on the loading of one tank truck (typical case) and one rail car (worst-case) assuming a closed
transfer system and accounting for displacement of vapors from the transfer line and from leaks in
equipment such as transfer line seals and valves. The exposure duration is the time required to load one
container, which is half an hour for tank trucks and one hour for rail cars. For the loading of drums with
NMP, EPA used the EPA/OAQPS AP-42 Loading Model and EPA/OPPT Mass Balance Model to
determine NMP volatilization to air and associated potential worker inhalation exposures, respectively.
These models use default parameter values and standard assumptions to provide screening level
assessments of inhalation and dermal exposures for container loading operations.
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Note that, to determine an exposure duration for the loading of drums during the manufacturing
scenario, EPA first determined annual throughput of NMP at manufacturing sites. To do so, EPA
divided the total NMP production volume of 161 million pounds (determined from 2016 CDR results;
(U.S. EPA. 2016a) by the 33 sites that reported to 2016 CDR (see Section 2.1.2.2). EPA assumes that
each of the 33 sites have the same annual throughput, regardless of whether the site manufactures or
imports NMP. Thus, the site throughput for manufacturing and importation sites is the same. To
determine the daily throughput of NMP at these sites, EPA assumed that sites operate 250 days per year.
Based on this throughput information and the model's assumed loading rate of 20 drums/hour, the model
determined an exposure duration of 2.06 hr/day for the loading of drums with NMP at manufacturing
sites (assuming the site only fills drums and no other container sizes, as a worst-case exposure scenario).
For both loading of bulk containers and drums, EPA calculated short-term and 8-hour TWA exposures
to workers during loading activities. The short-term TWA exposure is the weighted average exposure
during the entire exposure duration per shift, accounting for the number of loading events per shift. The
8-hour TWA exposure is the weighted average exposure during an entire 8-hour shift, assuming zero
exposures during the remainder of the shift. Table Apx A-l presents a summary of the exposure
modeling results in Rows 13 through 16.
EPA's modeled exposure concentrations for loading NMP into bulk containers are similar in value and
the same order of magnitude as those modeled by RIVM for closed-system NMP transfers. EPA's
modeled exposure concentrations for loading NMP into drums are the same magnitude but higher in
value than those modeled by RIVM for open-system NMP transfers. EPA's modeled exposure
concentrations represent a larger range of potential inhalation exposure concentrations than those
presented by RIVM; thus, EPA uses these modeled exposures in lieu of using the monitoring data or
modeled exposure in the RIVM Annex XV Proposal for a Restriction - NMP report. EPA uses the
modeled exposures in these Rows 13 through 16 as inputs for the PBPK model for worker inhalation
exposure over 8-hours and short-term.
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Table Apx A-l. Summary of Inhalation Monitoring Data for Manufacturing
Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or Sampling
Location
NMP Airborne Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample Time
Source
Data
Identifier
from Data
Extraction
and
Evaluation
Overall
Confidence
Rating from
Data
Extraction
and
Evaluation
Rationale for
Inclusion /
Exclusion
1
Storing,
conveying
Area
Listed as "storing, conveying." No
specific industries are listed.
50th percentile: below analytical
quantification limit of 0.42
90th percentile: 0.64
95th percentile: 1.155
13
Unknown
Unknown - Per source,
the sampling time is
greater than or equal to
1 hour and exposure
duration is greater than
or equal to 6 hours,
such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 -
129
Medium
Excluded -
unknown sample
times, worker
activities, and
sampling areas
2
Storing,
conveying
Unknown
Listed as "storing, conveying." No
specific industries are listed. Samples
taken in the presence of LEV.
50th percentile: 0.2 (below analytical
quantification limit of 0.42)
90th percentile: 0.7
95th percentile: 1.35
10
Unknown
Unknown - Per source,
the sampling time is
greater than or equal to
1 hour and exposure
duration is greater than
or equal to 6 hours,
such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 -
145
Medium
Excluded -
unknown sample
times, worker
activities, and
sampling areas
3
Closed system
transfers
Modeled using EasyTRA model
Transfer using closed systems -
varying levels of openness. Most
closed system.
0.04
Not applicable -
this is a modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 -
106
High
Excluded - EPA
modeled
exposures, as
shown in Rows
13 through 16
4
Closed system
transfers
Modeled using EasyTRA model
Transfer using closed systems -
varying levels of openness. Medium
closed system.
4.13
Not applicable -
this is a modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 -
106
High
Excluded - EPA
modeled
exposures, as
shown in Rows
13 through 16
5
Closed system
transfers
Modeled using EasyTRA model
Transfer using closed systems -
varying levels of openness. Least
closed system.
12.39
Not applicable -
this is a modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 -
106
High
Excluded - EPA
modeled
exposures, as
shown in Rows
13 through 16
6
Open system
transfers -
industrial setting
without LEV
Modeled using EasyTRA model
Loading and unloading from
containers using transfer lines or a
dedicated fill point. No ventilation.
Industrial setting.
17.35
Not applicable -
this is a modeled
exposure
Partial shift
4 hours
(RIVM. 2013)
3809440 -
108
High
Excluded - EPA
modeled
exposures, as
shown in Rows
13 through 16
7
Open system
transfers -
industrial setting
without LEV
Modeled using EasyTRA model
Loading and unloading from
containers using transfer lines or a
dedicated fill point. No ventilation.
Industrial setting.
14.46
Not applicable -
this is a modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 -
108
High
Excluded - EPA
modeled
exposures, as
shown in Rows
13 through 16
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Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or Sampling
Location
NMP Airborne Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample Time
Source
Data
Identifier
from Data
Extraction
and
Evaluation
Overall
Confidence
Rating from
Data
Extraction
and
Evaluation
Rationale for
Inclusion /
Exclusion
8
Open system
transfers -
commercial
setting without
LEV
Modeled using EasyTRA model
Loading and unloading from
containers using transfer lines or a
dedicated fill point. No ventilation.
Commercial setting.
14.46
Not applicable -
this is a modeled
exposure
Partial shift
1 hours
(RIVM. 2013)
3809440 -
108
High
Excluded -
commercial
settings are not
expected for
NMP
manufacturing
9
Open system
transfers -
commercial
setting without
LEV
Modeled using EasyTRA model
Loading and unloading from
containers using transfer lines or a
dedicated fill point. No ventilation.
Commercial setting.
17.35
Not applicable -
this is a modeled
exposure
Partial shift
4 hours
(RIVM. 2013)
3809440 -
108
High
Excluded -
commercial
settings are not
expected for
NMP
manufacturing
10
Open system
transfers - high
temperature NMP
- industrial setting
with LEV (95%)
Modeled using EasyTRA model
Loading and unloading from
containers using transfer lines or a
dedicated fill point. NMP handled at
elevated temperatures. Local exhaust
ventilation (95% efficiency).
Industrial setting.
3.1
Not applicable -
this is a modeled
exposure
Partial shift
4 hours
(RIVM. 2013)
3809440 -
108
High
Excluded - EPA
modeled
exposures, as
shown in Rows
13 through 16
11
Open system
transfers - high
temperature NMP
- industrial setting
with LEV (90%)
Modeled using EasyTRA model
Loading and unloading from
containers using transfer lines or a
dedicated fill point. NMP handled at
elevated temperatures. Local exhaust
ventilation (90% efficiency).
Industrial setting.
12.39
Not applicable -
this is a modeled
exposure
Partial shift
4 hours
(RIVM. 2013)
3809440 -
108
High
Excluded - EPA
modeled
exposures, as
shown in Rows
13 through 16
12
Open system
transfers - high
temperature NMP
- industrial setting
without LEV
Modeled using EasyTRA model
Loading and unloading from
containers using transfer lines or a
dedicated fill point. NMP handled at
elevated temperatures. No ventilation.
Industrial setting.
12.91
Not applicable -
this is a modeled
exposure
Partial shift
1 hour
(RIVM. 2013)
3809440 -
108
High
Excluded - EPA
modeled
exposures, as
shown in Rows
13 through 16
13
Transferring
NMP to / from
bulk containers
(tank trucks and
rail cars)
Modeled with Tank Truck and
Railcar Loading and Unloading
Release and Inhalation
Exposure Model
Manually transferring 100% NMP to /
from tank trucks (typical) and rail
cars (worst-case), including
equipment leaks
Typical = 0.76
Worst-case = 1.52
Not applicable -
this is a modeled
exposure
TWA (averaged
over exposure
duration)
transfer activity is 0.5
hours (typical) and 1
hour (worst-case)
Tank Truck
and Railcar
Loading and
Unloading
Release and
Inhalation
Exposure
Model
Not
applicable
Not applicable
Included as short-
term inhalation
exposure
concentration for
PBPK model
14
Transferring
NMP to / from
bulk containers
(tank trucks and
rail cars)
Modeled with Tank Truck and
Railcar Loading and Unloading
Release and Inhalation
Exposure Model
Manually transferring 100% NMP to /
from tank trucks (typical) and rail
cars (worst-case), including
equipment leaks
Typical = 0.047
Worst-case = 0.19
Not applicable -
this is a modeled
exposure
8-hour TWA
8 hours - transfer
activity is 0.5 hours
(typical) and 1 hour
(worst-case), with zero
exposure the remainder
of the shift
Tank Truck
and Railcar
Loading and
Unloading
Release and
Inhalation
Exposure
Model
Not
applicable
Not applicable
Included as 8-
hour worker
inhalation
exposure
concentration for
PBPK model
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Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or Sampling
Location
NMP Airborne Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample Time
Source
Data
Identifier
from Data
Extraction
and
Evaluation
Overall
Confidence
Rating from
Data
Extraction
and
Evaluation
Rationale for
Inclusion /
Exclusion
15
Transferring
NMP to / from
drains
Modeled with AY'.! OAOI'S .11'-
42 Loading Model and
EPA/OPPT Mass Balance
Model
Manually transferring 100% NMP to /
from drams
Typical = 1.65
Worst-case = 5.85
Not applicable -
this is a modeled
exposure
TWA (averaged
over exposure
duration)
Manufacturing &
Reoackaeine:
2.06 hours
Disposal:
0.603 hours
(U.S. EPA
2013a)
Not
applicable
Not applicable
Included as short-
term inhalation
exposure
concentration for
PBPK model
16
Transferring
NMP to / from
drums
Modeled with AY'.! OAOI'S AI'-
42 Loading Model and
EPA/OPPT Mass Balance
Model
Manually transferring 100% NMP to /
from drams
Manufacturing & Reoackaeine:
Typical = 0.427
Worst-case =1.51
Disposal:
Typical = 0.125
Worst-case = 0.441
Not applicable -
this is a
modelled
exposure
TWA (averaged
over exposure
duration)
8 hours - transfer
activity duration from
the above cell, with zero
exposure the remainder
of the shift
(U.S. EPA
2013a)
Not
applicable
Not applicable
Included as 8-
hour worker
inhalation
exposure
concentration for
PBPK model
N/A - Not Applicable.
145
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Peer Review Draft Document. Do not release or distribute.
A.2 Repackaging
EPA did not find inhalation monitoring data related to the repackaging of NMP. The same monitoring
data and modeled data presented in Appendix A. 1 for the manufacturing of NMP are also applicable to
repackaging of NMP, as these data apply to the transfers (i.e., loading and unloading) of NMP, which
occurs at both manufacturing and repackaging sites.
EPA uses the calculated PBPK input parameters for full-shift (8-hour TWA) and short-term (acute)
worker inhalation exposures presented in Rows 13 through 16 of Table Apx A-l in Appendix A.l. See
Appendix A. 1 for additional information on the calculation of these exposure concentrations.
A.3 Chemical Processing, Excluding Formulation
Table Apx A-2 summarizes the inhalation monitoring data that are available in published literature for
the use of NMP in non-incorporative processing activities. Rows 1 through 10 include air monitoring
data for NMP from a compilation of NMP monitoring data prepared by the German Institute for
Occupational Safety and Health (IFA) ( 2010). These data are for processing activities related to the
production of polymer activities, as well as for the storing and conveying of NMP. However, these data
do not include information on the associated worker activities, sampling areas, sampling times, and type
of storing and conveying systems associated with these data are unknown. EPA, therefore, cannot
determine the function of NMP at the sites conducting polymer processing activities or the type of
measurement taken. Thus, EPA excluded these data points from this analysis.
Rows 11 through 28 include air monitoring data that was submitted to EPA from E.I. DuPont De
Nemours & Company in response to a proposed TSCA Section 4 test rule on NMP. These data were
submitted in 1990 and were taken from 1983 to 1989, during polymer production using NMP. Some of
these data lack information on sample durations and explanation on what the associated worker activities
involve. Due to the age and lack of sample context, these data were rated of Medium quality. EPA found
data that was rated High quality, presented in Rows 29 through 38 and discussed further below, which
EPA used to estimate exposures for this scenario.
EPA summarized modeled inhalation exposure concentrations from the RIVM Annex XV Proposal for a
Restriction - NMP report (RIVM. ). These modeled inhalation exposure concentrations are for the
use of NMP as a process solvent or reagent in an industrial setting and include scenarios for closed
processing systems with various levels of enclosure as well as the handling of NMP at both ambient and
elevated temperatures. These data are all 8-hour TWA values and are presented in Rows 29 to 34 of
Table_Apx A-2.
In addition to the modeled exposures compiled from the RIVM Annex XV Proposal for a Restriction -
NMP report, EPA modeled potential worker inhalation exposures during the unloading of pure NMP.
The unloading activity during this scenario is expected to present a high potential for worker exposure
and is not already covered in the RIVM modeled exposures presented for this scenario. EPA modeled
these exposure concentrations consistent with the methodology presented in Appendix A.l for the
manufacturing of NMP. Refer to Appendix A. 1 for additional details on this modeling.
For the unloading of bulk containers containing pure NMP, EPA developed the Tank Truck and Railcar
Loading and Unloading Release and Inhalation Exposure Model, which calculates potential exposure
concentrations based on the unloading of one tank truck (typical case) and one rail car (worst-case). The
exposure duration is the time required to unload one container, which is half an hour for tank trucks and
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one hour for rail cars. For the unloading of drums containing NMP, EPA used the EPA/OAQPS AP-42
Loading Model and EPA/OPPTMass Balance Model to determine NMP volatilization to air and
associated potential worker inhalation exposures, respectively.
Note that, to determine an exposure duration for the unloading of drums at processing sites, EPA first
determined throughput of NMP at these sites. NMP processing is assessed in both this scenario and in
Section 2.4, Incorporation into Formulation, Mixture, or Reaction Product. EPA does not expect that
NMP is processed in both conditions of use, but that the production volume of NMP is split between
these conditions of use. EPA assumes that the entire production volume of NMP (161 million pounds
per 2016 CDR; ( ,) is processed and determined the throughput at processing sites by
dividing the production volume by the total number of sites assessed between the two processing
conditions of use (94 sites each per Sections 2.3.2.2 and 2.4.2.2) and by 250 days of operation per site
per year. Based on this daily site throughput, the capacity of drums, and an assumed unloading rate of 20
drums/hour, the model determined an exposure duration of 0.362 hours for processing sites (assuming
the site only unloads drums and no other container sizes).
For both unloading of bulk containers and drums, EPA calculated short-term and 8-hour TWA
exposures to workers during unloading activities. The short-term TWA exposure is the weighted average
exposure during the entire exposure duration per shift, accounting for the number of unloading events
per shift. The 8-hour TWA exposure is the weighted average exposure during an entire 8-hour shift,
assuming zero exposures during the remainder of the shift. Table Apx A-2 presents a summary of the
exposure modeling results in Rows 35 through 38. EPA used the short-term modeled exposure
concentrations for unloading drums (Row 37) as a conservative exposure scenario as input for the PBPK
model for worker short-term exposures.
To determine potential full-shift inhalation exposure concentration, EPA calculated the central tendency
(50th percentile) and worst-case (95th percentile) 8-hour TWA exposure concentrations from the data in
Rows 29 through 35, and 38.
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Table Apx A-2. Summary of Inhalation Monitoring Data for Chemical Processing, Excluding Formulation
Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration (mg/m3)
Number
of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence Rating
from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
1
Processing - polymer
Area
Listed as "plastics and
plastic foam, processing and
manufacture; manufacture
and processing of rubber
products." Worker activities
and sampling areas are
unknown.
50th percentile: 0.3
(below analytical
quantification limit of
0.42)
90th percentile: 3
95thpercentile: 3.5
40
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 102
Medium
Excluded - unknown worker
activities and sampling areas
2
Processing - polymer
Personal
Listed as "plastics and
plastic foam, processing and
manufacture; manufacture
and processing of rubber
products." Worker activities
and sampling areas are
unknown.
50th percentile: 0.35
(below analytical
quantification limit of
0.42)
90th percentile: 2.93
95th percentile: 4.985
61
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 110
Medium
Excluded - unknown worker
activities and sampling areas
3
Processing - polymer
Unknown
Listed as "plastics and
plastic foam, processing and
manufacture; manufacture
and processing of rubber
products." Worker activities
and sampling areas are
unknown. Samples taken in
the presence of LEV.
50th percentile: 0.5
90thpercentile: 3.45
95th percentile: 4.775
65
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 117
Medium
Excluded - unknown worker
activities and sampling areas
4
Processing - polymer
Unknown
Listed as "plastics and
plastic foam, processing and
manufacture; manufacture
and processing of rubber
products." Worker activities
and sampling areas are
unknown. Samples taken in
the absence of LEV.
50th percentile: 0.2
(below analytical
quantification limit of
0.42)
90th percentile: 1.92
95th percentile: 2.9
22
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 124
Medium
Excluded - unknown worker
activities and sampling areas
5
Processing - polymer
Unknown
Listed as "plastics and
plastic foam, processing and
manufacture; manufacture
and processing of rubber
products." Work area group
listed as "Foaming." These
data are likely a subset of the
above data.
50th percentile: 0.2
(below analytical
quantification limit of
0.42)
90th percentile: 0.84
95th percentile: 1.72
14
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 160
Medium
Excluded - unknown worker
activities and sampling areas
6
Processing - polymer
Unknown
Listed as "plastics and
plastic foam, processing and
manufacture; manufacture
and processing of rubber
products." Work area group
listed as "Surface coating,
painting, coating." These
data are likely a subset of the
above data.
50th percentile: 0.3
(below analytical
quantification limit of
0.42)
90th percentile: 2
95th percentile: 2.6
28
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 161
Medium
Excluded - unknown worker
activities and sampling areas
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Number
of
Samples
Data Identifier
Overall
Confidence Rating
from Data
Extraction and
Evaluation
Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration (mg/m3)
Type of
Measurement
Sample Time
Source
from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
50th percentile: below
analytical quantification
limit of 0.42
90th percentile: 0.38
(below analytical
quantification limit of
0.42)
95th percentile: 0.49
Unknown - Per source, the
sampling time greater than or
7
Processing - polymer
Personal
Work group area is listed as
"foaming." No additional
details are provided.
11
Unknown
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
(IFA. 2010)
4271620 - 136
Medium
Excluded - unknown worker
activities and sampling areas
measurement
Unknown - Per source, the
Work group area is listed as
50th percentile: below
sampling time greater than or
8
Processing - polymer
Unknown
"foaming." Samples taken in
the presence of LEV. No
additional details are
provided.
analytical quantification
limit of 0.42
90th percentile: 0.88
95th percentile: 1.84
13
Unknown
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 147
Medium
Excluded - unknown worker
activities and sampling areas
Unknown - Per source, the
50th percentile: below
sampling time greater than or
9
Storing, conveying
Area
Listed as "storing,
conveying." No specific
industries are listed.
analytical quantification
limit of 0.42
90th percentile: 0.64
95th percentile: 1.155
13
Unknown
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 129
Medium
Excluded - unknown worker
activities and sampling areas
10
Storing, conveying
Unknown
Listed as "storing,
conveying." No specific
industries are listed. Samples
taken in the presence of
LEV.
50th percentile: 0.2
(below analytical
quantification limit of
0.42)
90th percentile: 0.7
95th percentile: 1.35
10
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to
6 hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 145
Medium
Excluded - unknown worker
activities and sampling areas
11
Processing - polymer
Personal
Organic polymer prep and
solvent recovery
Mean: 0.02
Maximum: 0.81
21
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100-101
Medium
Excluded - data is from the 1980s
and sample duration is unknown
12
Processing - polymer
Personal
Manufacture of composite
prepreg
0.81
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 102
Medium
Excluded - data is from the 1980s
and sample duration is unknown
13
Processing - polymer
Personal
Manufacture of composite
prepreg
4.05
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 102
Medium
Excluded - data is from the 1980s
and sample duration is unknown
14
Processing - polymer
Area
Resin heating mill hood
24.33
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 103
Medium
Excluded - data is from the 1980s
and sample duration is unknown
15
Processing - polymer
Area
Resin heating mill hood
4.05
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 103
Medium
Excluded - data is from the 1980s
and sample duration is unknown
16
Processing - polymer
Personal
Curing composite article at
800 F
<0.41
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 106
Medium
Excluded - data is from the 1980s
and sample duration is unknown
17
Processing - polymer
Area
Curing composite article at
800 F
<0.41
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 107
Medium
Excluded - data is from the 1980s
and sample duration is unknown
18
Processing - polymer
Personal
Devolatilizing composite
article in laboratory hood
<0.41
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 108
Medium
Excluded - data is from the 1980s
and sample duration is unknown
19
Processing - polymer
Personal
Devolatilizing composite
article in ventilated press
<0.41
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 109
Medium
Excluded - data is from the 1980s
and sample duration is unknown
20
Processing - polymer
Area
Devolatilizing composite
article in ventilated press
<0.41
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 110
Medium
Excluded - data is from the 1980s
and sample duration is unknown
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Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration (mg/m3)
Number
of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence Rating
from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
21
Processing - polymer
Personal
Impregnating fibers with
resin in laboratory hood
<0.41
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 111
Medium
Excluded - data is from the 1980s
and sample duration is unknown
22
Processing - polymer
Personal
Cut patterns from prepreg
and devolatilized for 2 hours
<0.41
1
Unknown
2 hours
(DuPont. 1990)
4214100 - 112
Medium
Excluded - data is from the 1980s
23
Processing - polymer
Area
Cut patterns from prepreg
and devolatilized for 2 hours
<0.41
2
Unknown
2 hours
(DuPont. 1990)
4214100 - 113
Medium
Excluded - data is from the 1980s
24
Processing - polymer
Personal
Operator cut patterns from
prepreg wearing skin
protective equipment
<0.41
1
Unknown
unknown - greater than 5.5
hours
(DuPont. 1990)
4214100 - 114
Medium
Excluded - data is from the 1980s
and sample duration is unknown
25
Processing - polymer
Personal
Clean up of 310 F heater
plates
21.08
1
Unknown
9 minutes
(DuPont. 1990)
4214100 - 115
Medium
Excluded - data is from the 1980s
26
Processing - polymer
Personal
Clean up of 310 F heater
plates
15.00
1
Unknown
13 minutes
(DuPont. 1990)
4214100 - 116
Medium
Excluded - data is from the 1980s
27
Processing - polymer
Personal
Clean up of 310 F heater
plates
40.55
1
Unknown
17 minutes
(DuPont. 1990)
4214100 - 116
Medium
Excluded - data is from the 1980s
28
Processing - polymer
Personal
Clean up of 310 F heater
plates
48.65
1
Unknown
13 minutes
(DuPont. 1990)
4214100 - 117
Medium
Excluded - data is from the 1980s
29
Processing - NMP used
as a process solvent or
reagent - closed system
Modeled
using
EasyTRA
model
Manufacture of chemicals
(NMP used as a process
solvent or reagent) in a
closed system at ambient
temperatures. Most enclosed
system. Industrial setting.
No local exhaust ventilation.
0.04
Not
applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Included - EPA calculated the
central tendency and worst-case
8-hour TWA exposure
concentrations from the data in
Rows 11 through 17, and 20
30
Processing - NMP used
as a process solvent or
reagent - closed system
Modeled
using
EasyTRA
model
Manufacture of chemicals
(NMP used as a process
solvent or reagent) in a
closed system at ambient
temperatures. Medium level
of enclosed system.
Industrial setting. No local
exhaust ventilation.
4.13
Not
applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Included - EPA calculated the
central tendency and worst-case
8-hour TWA exposure
concentrations from the data in
Rows 11 through 17, and 20
31
Processing - NMP used
as a process solvent or
reagent - closed system
Modeled
using
EasyTRA
model
Manufacture of chemicals
(NMP used as a process
solvent or reagent) in a
closed system at ambient
temperatures. Least enclosed
system. Industrial setting.
No local exhaust ventilation.
12.39
Not
applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Included - EPA calculated the
central tendency and worst-case
8-hour TWA exposure
concentrations from the data in
Rows 11 through 17, and 20
32
Processing - NMP used
as a process solvent or
reagent - closed system -
elevated temperature
Modeled
using
EasyTRA
model
Manufacture of chemicals
(NMP used as a process
solvent or reagent) in a
closed system at an elevated
temperature up to 180C.
Medium level of enclosed
system. Industrial setting.
Local exhaust ventilation
with 90% capture efficiency.
0.04
Not
applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Included - EPA calculated the
central tendency and worst-case
8-hour TWA exposure
concentrations from the data in
Rows 11 through 17, and 20
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Number
of
Samples
Data Identifier
Overall
Confidence Rating
from Data
Extraction and
Evaluation
Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration (mg/m3)
Type of
Measurement
Sample Time
Source
from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
Manufacture of chemicals
(NMP used as a process
33
Processing - NMP used
as a process solvent or
reagent - closed system -
elevated temperature
Modeled
using
EasyTRA
model
solvent or reagent) in a
closed system at an elevated
temperature up to 180C.
Least enclosed system.
Industrial setting. Local
exhaust ventilation with 90%
capture efficiency.
10.33
Not
applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Included - EPA calculated the
central tendency and worst-case
8-hour TWA exposure
concentrations from the data in
Rows 11 through 17, and 20
Manufacture of chemicals
34
Processing - NMP used
as a process solvent or
reagent - closed system -
elevated temperature
Modeled
using
EasyTRA
model
(NMP used as a process
solvent or reagent) in a
closed system at an elevated
temperature up to 180C.
Least enclosed system.
Industrial setting. No local
exhaust ventilation.
20.65
Not
applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Included - EPA calculated the
central tendency and worst-case
8-hour TWA exposure
concentrations from the data in
Rows 11 through 17, and 20
Modeled
with Tank
35
Transferring NMP to /
from bulk containers
(tank trucks and rail cars)
Truck and
Railcar
Loading and
Unloading
Release and
Inhalation
Exposure
Model
Manually transferring 100%
NMP to / from tank trucks
(typical) and rail cars (worst-
case), including equipment
leaks
Typical = 0.047
Worst-case = 0.95
Not
applicable
- this is a
modeled
exposure
8-hour TWA
8 hours - transfer activity is 0.5
hours (typical) and 1 hour
(worst-case), with zero
exposure the remainder of the
shift
Tank Truck and
Railcar Loading and
Unloading Release
and Inhalation
Exposure Model
Not applicable
Not applicable
Included - EPA calculated the
central tendency and worst-case
8-hour TWA exposure
concentrations from the data in
Rows 11 through 17, and 20
Modeled
with Tank
Truck and
Railcar
Loading and
Unloading
Release and
Inhalation
Exposure
Model
Transferring 100% NMP to /
from tank trucks (typical)
and rail cars (worst-case),
including equipment leaks
Not
TWA
(averaged
over exposure
duration)
Tank Truck and
Excluded - EPA used the
36
Transferring NMP to /
from bulk containers
(tank trucks and rail cars)
Typical = 0.76
Worst-case = 7.62
applicable
- this is a
modeled
exposure
transfer activity is 0.5 hours
(typical) and 1 hour (worst-
case)
Railcar Loading and
Unloading Release
and Inhalation
Exposure Model
Not applicable
Not applicable
modeled short-term exposure
from loading drums (Row 19) as
a more conservative exposure
scenario
Modeled
with
37
Transferring NMP to /
from drums
EPA/OAOPS
AP-42
Loading
Model and
EPA/0PPT
Mass
Balance
Model
Manually transferring 100%
NMP to / from drums
Typical = 1.65
Worst-case = 5.85
Not
applicable
- this is a
modelled
exposure
TWA
(averaged
over exposure
duration)
Transfer activity is 0.362 hours,
based on assumed throughput
(U.S. EPA. 2013a)
Not applicable
Not applicable
Included as short-term inhalation
exposure concentration for PBPK
model
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Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration (mg/m3)
Number
of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence Rating
from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
38
Transferring NMP to /
from drums
Modeled
with
EPA/OAOPS
AP-42
Loading
Model and
EPA/OPPT
Mass
Balance
Model
Manually transferring 100%
NMP to / from drums
Typical = 0.075
Worst-case = 0.265
Not
applicable
- this is a
modelled
exposure
TWA
(averaged
over exposure
duration)
8 hours - transfer activity is
0.362 hours, with zero
exposure the remainder of the
shift
(U.S. EPA. 2013a)
Not applicable
Not applicable
Included - EPA calculated the
central tendency and worst-case
8-hour TWA exposure
concentrations from the data in
Rows 11 through 17, and 20
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A.4 Incorporation into Formulation, Mixture, or Reaction Product
TableApx A-3 shows inhalation monitoring data that are available in published literature for
incorporation of NMP into a formulation, mixture, or reaction product. Rows 1 through 14 include air
monitoring data for NMP at a site that formulate adhesives. These data include both 8-hour TWA
exposure concentrations, as well as short-term exposure concentrations. EPA used the 8-hour TWA data
in Rows 1 through 7 to calculate central tendency (50th percentile) and worst-case (95th percentile)
potential full-shift worker inhalation exposure concentrations. EPA calculated a 50th percentile of 2.8
mg/m3 and a 95th percentile of 12.8 mg/m3 from these data. EPA used the 95th percentile 8-hour TWA
value of 12.8 mg/m3 as input for the PBPK model for this scenario.
EPA excluded the monitoring data in Row 8 through 14, as indicated in Table Apx A-3. The monitoring
data in Row 15 is for the formulation of printing inks and is not NMP-specific; thus, EPA excluded
these data in favor of the NMP monitoring data as described above. The monitoring data in Rows 16
through 27 are from a compilation of NMP monitoring data prepared by the German Institute for
Occupational Safety and Health (IFA) ( ). However, the associated worker activities, sampling
areas, sampling times, and type of storing and conveying systems associated with these data are
unknown. EPA therefore excluded these data points from this analysis.
In addition to personal monitoring data, EPA summarized modeled inhalation exposure concentrations
from the RIVM Annex XV Proposal for a Restriction - NMP report (RIVM. 2013). These exposure
concentrations were modeled using the EasyTRA model, which is based on the European Center for
Ecotoxicology and Toxicology of Chemicals (ECETOC) Targeted Risk Assessment (TRA) tool. These
modeled inhalation exposure concentrations include all formulation activities and include scenarios for
open and closed processing systems as well as for formulation at both ambient and elevated
temperatures. These data are presented in Rows 28 to 38 of Table Apx A-3. However, EPA uses NMP
monitoring data as described above in lieu of modeled data.
In addition to the monitoring data, EPA modeled potential worker inhalation exposures unloading of
pure NMP at formulation sites. The unloading activity during this scenario is expected to present a high
potential for worker exposure and is not already covered in the RIVM modeled exposures presented for
this scenario. EPA modeled these exposure concentrations consistent with the methodology presented in
Appendix A.l for the manufacturing of NMP. Refer to Appendix A.l for additional details on this
modeling.
For the unloading of bulk containers containing pure NMP, EPA developed the Tank Truck and Railcar
Loading and Unloading Release and Inhalation Exposure Model, which calculates potential exposure
concentrations based on the loading of one tank truck (typical case) and one rail car (worst-case). The
exposure duration is the time required to load one container, which is half an hour for tank trucks and
one hour for rail cars. For the unloading of drums containing pure NMP, EPA used the EPA/OAQPS
AP-42 Loading Model and EPA/OPPTMass Balance Model to determine NMP volatilizations to air and
associated potential worker inhalation exposures, respectively.
Note that, to determine an exposure duration for the unloading of drums at processing sites, EPA first
determined throughput of NMP at these sites. NMP processing is assessed in both this scenario and in
Section 2.3, Chemical Processing, Excluding Formulation. EPA does not expect that NMP is processed
in both conditions of use, but that the production volume of NMP is split between these conditions of
use. EPA assumes that the entire production volume of NMP (161 million pounds per the (
2016a) is processed and determined the throughput at processing sites by dividing the production
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volume by the total number of sites assessed between the two processing conditions of use (94 sites each
per Sections 2.3.2.2 and 2.4.2.2) and by 250 days of operation per site per year. Based on this daily site
throughput, the capacity of drums, and an assumed unloading rate of 20 drums/hour, the model
determined an exposure duration of 0.362 hours for processing sites (assuming the site only unloads
drums and no other container sizes).
For both unloading of bulk containers and drums, EPA calculated short-term and 8-hour TWA
exposures to workers during unloading activities. The short-term TWA exposure is the weighted average
exposure during the entire exposure duration per shift, accounting for the number of unloading events
per shift. The 8-hour TWA exposure is the weighted average exposure during an entire 8-hour shift,
assuming zero exposures during the remainder of the shift. Table Apx A-3 presents a summary of the
exposure modeling results in Rows 39 through 42. EPA used the central tendency (50th percentile) short-
term and 8-hour TWA modeled exposure concentrations for unloading drums (Row 19 and Row 20) as
the central tendency input for the PBPK model, in addition to the monitoring data described above.
In addition to the formulation of liquid products, EPA identified formulation activities that may result in
potential worker exposures to particulates containing NMP. Specifically, these include plastics
compounding and blending of granular fertilizers, as described in Section 2.4.1. Due to the lower
volatility of NMP, workers may be potentially exposed to NMP in inhaled dusts. EPA did not find
monitoring data for NMP at sites that compound plastic or blend granular fertilizers.
The Draft 2014 ESD on Use of Additives in Plastics Compounding summarized OSHA monitoring data
for total dust at compounding sites that was compiled in ( 014). These OSHA data are
personal monitoring samples taken between 2006 and 2010 for particulates not otherwise regulated
(PNOR) at facilities whose operations fall within the NAICS code 325991, Custom Compounding of
Purchased Resins. However, these data are not activity-specific and have varying sample times ranging
from about one to four hours. Thus, consistent with the methodology presented in the Draft 2014 ESD
on Use of Additives in Plastics Compounding, EPA uses the OSHA PEL for Total Dust of 15 mg/m3 to
assess potential worker inhalation exposures to solids in this scenario. EPA identified five solid polymer
resins with residual NMP ranging from 0.0017 to seven weight percent NMP and two granular
agricultural chemicals with NMP content of less than 0.1 and less than five weight percent NMP. EPA
multiplied the OSHA PEL by each of the identified NMP weight fractions to determine the potential
NMP inhalation exposure concentrations, then calculated the central tendency (50th percentile) and
worst-case (95th percentile) to be 0.75 and 0.96 mg/m3, respectively, from these seven exposure
concentrations. EPA did not use these values as input to the PBPK model because the model does not
account for solid NMP.
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Table Apx A-3. Summary oi
' Inhalation Monil
toring Data for Incorporation into Formulation, Mixture, or Reaction Product
Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from
Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
1
Formulation of adhesives
Personal
Maintenance, foreman
1
1
8-hour TWA
8 hours
(Bader et al..
2006)
3539720 - 106
High
Included - EPA calculated
central tendency and worst-
case 8-hour TWA exposure
concentrations from the data
in Rows 1 through 7
2
Formulation of adhesives
Personal
Maintenance
2.8
1
8-hour TWA
8 hours
(Bader et al..
2006)
3539720 - 106
High
Included - EPA calculated
central tendency and worst-
case 8-hour TWA exposure
concentrations from the data
in Rows 1 through 7
3
Formulation of adhesives
Personal
Bottling, shipping
0.9
1
8-hour TWA
8 hours
(Bader et al..
2006)
3539720 - 106
High
Included - EPA calculated
central tendency and worst-
case 8-hour TWA exposure
concentrations from the data
in Rows 1 through 7
4
Formulation of adhesives
Personal
Maintenance, cleaning
2.3
1
8-hour TWA
8 hours
(Bader et al..
2006)
3539720 - 107
High
Included - EPA calculated
central tendency and worst-
case 8-hour TWA exposure
concentrations from the data
in Rows 1 through 7
5
Formulation of adhesives
Personal
Mixing, stirrer cleaning
3.4
1
8-hour TWA
8 hours
(Bader et al..
2006)
3539720 - 109
High
Included - EPA calculated
central tendency and worst-
case 8-hour TWA exposure
concentrations from the data
in Rows 1 through 7
6
Formulation of adhesives
Personal
Mixing, stirrer cleaning
6.6
1
8-hour TWA
8 hours
(Bader et al..
2006)
3539720 - 109
High
Included - EPA calculated
central tendency and worst-
case 8-hour TWA exposure
concentrations from the data
in Rows 1 through 7
7
Formulation of adhesives
Personal
Vessel cleaning
15.5
1
8-hour TWA
8 hours
(Bader et al..
2006)
3539720 - 111
High
Included - EPA calculated
central tendency and worst-
case 8-hour TWA exposure
concentrations from the data
in Rows 1 through 7
8
Formulation of adhesives
Personal
Maintenance, cleaning
5.9
1
Peak
42 min
(Bader et al..
2006)
3539720 - 108
High
Excluded - these data are
short-term
9
Formulation of adhesives
Personal
Mixing, stirrer cleaning
18.7
1
Peak
19 min
(Bader et al..
2006)
3539720 - 110
High
Excluded - these data are
short-term
10
Formulation of adhesives
Personal
Vessel cleaning
18
1
Peak
102 min
(Bader et al..
2006)
3539720 - 104
High
Excluded - these data are
short-term
11
Formulation of adhesives
Personal
Vessel cleaning
85
1
Peak
5 min
(Bader et al..
2006)
3539720 - 112
High
Excluded - these data are
short-term
12
Formulation of adhesives
Personal
manual vessel and fittings cleaning
Mean: 10.7 to 18.0
Unknown
Short term
NR
(Bader et al..
2006)
3539720 - 104
High
Excluded - these data are
short-term
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Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from
Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
13
Formulation of adhesives
Area
Production area
Mean: 3.0
Unknown
NR
NR
(Bader et al..
2006)
3539720 - 103
High
Excluded - type of
measurement is unknown
14
Formulation of adhesives
Area
Bottling and shipping department
Mean: 0.2
Unknown
NR
NR
(Bader et al..
2006)
3539720 - 105
High
Excluded - type of
measurement is unknown
15
formulation of paste and
liquid printing inks
Unknown
Average sample concentration at a
printing inks manufacturing site that
produces paste (75%) and liquid
(assumed 25%) inks
2 (concentration of
particulates, not
NMP-specific)
Unknown
8-hour TWA
8 hours
(U.S. EPA.
2001)
Not applicable
Not applicable
Excluded - This sample
result is not for NMP, but for
particulates in general
16
Storing, conveying
Area
Listed as "storing, conveying." No
specific industries are listed.
50th percentile:
below analytical
quantification limit
of 0.42
90th percentile:
0.64
95th percentile:
1.155
13
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 129
Medium
Excluded - unknown worker
activities and sampling areas
17
Storing, conveying
Unknown
Listed as "storing, conveying." No
specific industries are listed. Samples
taken in the presence of LEV.
50th percentile: 0.2
(below analytical
quantification limit
of 0.42)
90th percentile: 0.7
95th percentile:
1.35
10
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 145
Medium
Excluded - unknown worker
activities and sampling areas
18
Manufacture / processing
of coatings, glue,
adhesives
Area
Listed as "chemical industry and
mineral processing," including
manufacture / processing of coatings,
glue, adhesives. Worker activities and
sampling areas are unknown.
50th percentile:
0.175 (below
analytical
quantification limit
of 0.42)
90th percentile:
13.41
95th percentile:
16.93
11
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 101
Medium
Excluded - unknown worker
activities and sampling areas
19
Manufacture / processing
of coatings, glue,
adhesives
Personal
Listed as "chemical industry and
mineral processing," including
manufacture / processing of coatings,
glue, adhesives. Worker activities and
sampling areas are unknown.
50th percentile:
0.45
90th percentile: 6
95th percentile:
9.75
30
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 109
Medium
Excluded - unknown worker
activities and sampling areas
20
Manufacture / processing
of coatings, glue,
adhesives
Unknown
Listed as "chemical industry and
mineral processing," including
manufacture / processing of coatings,
glue, adhesives. Worker activities and
sampling areas are unknown. Samples
taken in the presence of LEV.
50th percentile:
0.45
90th percentile:
12.5
95th percentile:
16.8
30
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620- 116
Medium
Excluded - unknown worker
activities and sampling areas
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Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from
Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
21
Manufacture / processing
of coatings, glue,
adhesives
Unknown
Listed as "chemical industry and
mineral processing," including
manufacture / processing of coatings,
glue, adhesives. Work area group listed
as "mixing, pressing." These data are
likely a subset of the above data.
50th percentile: 0.4
(below analytical
quantification limit
of 0.42)
90th percentile: 4.5
95th percentile: 6.2
14
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 159
Medium
Excluded - unknown worker
activities and sampling areas
22
Formulation - Mixing,
pressing
Personal
Listed as work group area "mixing,
pressing (compacting)." No additional
details provided.
50th percentile:
0.35 (below
analytical
quantification limit
of 0.42)
90th percentile:
3.45
95th percentile:
5.875
21
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 135
Medium
Excluded - unknown worker
activities and sampling areas
23
Formulation - Mixing,
pressing
Unknown
Listed as work group area "mixing,
pressing (compacting)." Samples taken
in the presence of LEV. No additional
details provided.
50th percentile:
below analytical
quantification limit
of 0.42
90th percentile:
3.45
95th percentile:
5.875
21
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 146
Medium
Excluded - unknown worker
activities and sampling areas
24
Processing of liquid
coating materials
Unknown
Mfg. and processing of metals -
processing of liquid coating materials
50th percentile: 0.2
below analytical
quantification limit
of 0.42
90th percentile:
13.45
95th percentile:
86.9
19
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 125
Medium
Excluded - unknown worker
activities and sampling areas
25
Processing of liquid
coating materials
Unknown
Mfg. and processing of metals -
processing of liquid coating materials
50th percentile:
0.55
90th percentile: 4
95th percentile: 6.5
55
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620- 119
Medium
Excluded - unknown worker
activities and sampling areas
26
Processing of liquid
coating materials
Personal
Mfg. and processing of metals -
processing of liquid coating materials
50th percentile: 0.5
90th percentile:
2.72
95th percentile: 3
44
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620- 111
Medium
Excluded - unknown worker
activities and sampling areas
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Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from
Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
27
Processing of liquid
coating materials
Area
Mfg. and processing of metals -
processing of liquid coating materials
50th percentile: 0.2
below analytical
quantification limit
of 0.42
90th percentile:
13.41
95th percentile:
24.65
43
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 104
Medium
Excluded - unknown worker
activities and sampling areas
28
Formulation - Closed
system - Including all
formulation activities
Modeled using
EasyTRA
model
Formulation of products at ambient
temperature in a closed system. Most
enclosed system. Industrial setting. No
local exhaust ventilation.
0.04
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
29
Formulation - Closed
system - Including all
formulation activities
Modeled using
EasyTRA
model
Formulation of products at ambient
temperature in a closed system. Medium
level of enclosed system. Industrial
setting. No local exhaust ventilation.
4.13
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
30
Formulation - Closed
system - Including all
formulation activities
Modeled using
EasyTRA
model
Formulation of products at ambient
temperature in a closed system. Least
enclosed system. Commercial and
industrial settings. No local exhaust
ventilation.
12.39
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
31
Formulation - Closed
system - Elevated
temperature - Including all
formulation activities
Modeled using
EasyTRA
model
Formulation of products at an elevated
temperature up to 120C in a closed
system. Most enclosed system.
Industrial setting. No local exhaust
ventilation.
0.04
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
32
Formulation - Closed
system - Elevated
temperature - Including all
formulation activities
Modeled using
EasyTRA
model
Formulation of products at an elevated
temperature up to 120C in a closed
system. Medium level of enclosed
system. Industrial setting. No local
exhaust ventilation.
20.65
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
33
Formulation - Closed
system - Elevated
temperature - Including all
formulation activities
Modeled using
EasyTRA
model
Formulation of products at an elevated
temperature up to 120C in a closed
system. Least enclosed system.
Industrial setting. Local exhaust
ventilation with 90% capture efficiency.
4.13
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
34
Formulation - Open system
- Elevated temperature -
Including all formulation
activities
Modeled using
EasyTRA
model
Mixing and blending products at an
elevated temperature up to 60C.
Industrial setting. No local exhaust
ventilation.
20.65
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
35
Formulation - Open system
- Elevated temperature -
Including all formulation
activities
Modeled using
EasyTRA
model
Mixing and blending products at an
elevated temperature up to 120C.
Industrial setting. Local exhaust
ventilation with 90% capture efficiency.
20.65
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
36
Formulation - Open system
- Elevated temperature -
Including all formulation
activities
Modeled using
EasyTRA
model
Mixing and blending products at an
elevated temperature up to 60C.
Commercial setting. No local exhaust
ventilation.
17.35
Not applicable
- this is a
modeled
exposure
Partial shift
4 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
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Overall
NMP Airborne
Concentration
(mg/m3)
Data Identifier
Confidence
Row
Occupational Exposure
Scenario
Type of
Sample
Worker Activity or Sampling
Location
Number of
Samples
Type of
Measurement
Sample Time
Source
from Data
Extraction and
Rating from
Data
Rationale for Inclusion /
Exclusion
Evaluation
Extraction and
Evaluation
37
Formulation - Loading
Modeled using
EasyTRA
model
Filling containers with final product
(assumed) at ambient temperatures.
Industrial setting. No local exhaust
ventilation.
14.46
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
38
Formulation - Loading -
Elevated temperature
Modeled using
EasyTRA
model
Filling containers with final product
(assumed) at an elevated temperature up
to 120C. Industrial setting. Local
exhaust ventilation with 90% capture
efficiency.
20.65
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 110
High
Excluded - EPA uses
monitoring data over
modeled data
Modeled with
Tank Truck
and Railcar
Loading and
Unloading
Release and
Inhalation
Exposure
Model
Tank Truck
and Railcar
39
Transferring NMP to /
from bulk containers (tank
trucks and rail cars)
Transferring 100% NMP to / from tank
trucks (typical) and rail cars (worst-
case), including equipment leaks
Typical = 0.047
Worst-case = 0.95
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours - transfer activity is 0.5
hours (typical) and 1 hour (worst-
case), with zero exposure the
remainder of the shift
Loading and
Unloading
Release and
Inhalation
Exposure
Model
Not applicable
Not applicable
Excluded - EPA uses
monitoring data over
modeled data
Modeled with
Tank Truck
and Railcar
Loading and
Unloading
Release and
Inhalation
Exposure
Model
Tank Truck
and Railcar
40
Transferring NMP to /
from bulk containers (tank
trucks and rail cars)
Transferring 100% NMP to / from tank
trucks (typical) and rail cars (worst-
case), including equipment leaks
Typical = 0.76
Worst-case = 7.62
Not applicable
- this is a
modeled
exposure
TWA
(averaged over
exposure
duration)
transfer activity is 0.5 hours
(typical) and 1 hour (worst-case)
Loading and
Unloading
Release and
Inhalation
Exposure
Model
Not applicable
Not applicable
Excluded - EPA uses
monitoring data over
modeled data
Modeled with
EPA/OAOPS
AP-42
Not applicable
TWA
Included as short-term
41
Transferring NMP to /
from drums
Loading
Model and
EPA/0PPT
Mass Balance
Model
Manually transferring 100% NMP to /
from drums
Typical = 1.65
Worst-case = 5.85
- this is a
modelled
exposure
(averaged over
exposure
duration)
Transfer activity is 0.362 hours,
based on assumed throughput
(U.S. EPA.
2013a)
Not applicable
Not applicable
inhalation exposure
concentration for PBPK
model
Modeled with
EPA/OAOPS
42
Transferring NMP to /
from drums
AP-42
Loading
Model and
EPA/OPPT
Mass Balance
Model
Manually transferring 100% NMP to /
from drums
Typical = 0.075
Worst-case = 0.265
Not applicable
- this is a
modelled
exposure
TWA
(averaged over
exposure
duration)
8 hours - transfer activity is 0.362
hours, with zero exposure the
remainder of the shift
(U.S. EPA.
2013a)
Not applicable
Not applicable
Excluded - EPA uses
monitoring data over
modeled data
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A.5 Metal Finishing
TableApx A-4 shows inhalation monitoring data that are available in published literature for use of
NMP-based metal finishing products. In addition to personal monitoring data, EPA summarized
modeled inhalation exposure concentrations from the RIVM Annex XV Proposal for a Restriction -
NMP report (RIVM. 2013). These exposure concentrations were modeled using the EasyTRA model,
which is based on the European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC)
Targeted Risk Assessment (TRA) tool, and the Stoffenmanager risk assessment software. The ECHA
report modeled potential inhalation exposures during generic application scenarios, specifically the dip,
roll/brush, and spray application of formulations containing NMP. These modeled inhalation exposure
concentrations are presented in Rows 3 to 7 of Table Apx A-4.
The data in Rows 1 through 4 are from a compilation of monitoring data by the German Institute for
Occupational Safety and Health (IFA). These data are listed as "foundries" and "manufacture and
processing of metals" (IF A. 2010). EPA is unsure how NMP is used at the companies that fall within
these industry categories. It is uncertain if the exposure monitoring data are 8-hour TWA values, but
IFA indicates that they are representative of shift measurements ( 10). However, these data do not
include any information regarding worker activities or sampling areas that can be used to determine the
appropriate occupational exposure scenario.
While there are no personal monitoring data for spray application of metal formulations, there are data
for the spray application of paints and coatings. EPA summarized and used these data in Section 2.5.
Due to lack of data for this scenario, EPA used the same low-end, mean, and high-end values for spray
application of paints and coatings in Section 2.7 as surrogate (surrogate work activities using NMP) for
this scenario.
EPA also did not find any personal monitoring data for dip application of metal finishing fluids. While
EPA did not find monitoring data for dip application of metal finishing fluids containing NMP, EPA did
find monitoring data for the dip application of cleaning products containing NMP. EPA summarized and
used these data in Section 2.13. Due to lack of data for this scenario, EPA used the same central
tendency and worst-case values calculated for dip application of cleaning products in Section 2.13 as
surrogate (surrogate work activities using NMP) for this scenario.
Finally, EPA did not find personal monitoring data on the brush application of metal finishing
formulations. Thus, EPA assesses potential inhalation exposures for this scenario consistent with the
approach used for brush application of paints, coatings, adhesives, and sealants used in Section 2.7.
Specifically, EPA assesses the concentration of the modeled value shown in Row 7 of Table Apx A-4.
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Table Apx A-4. Summary of Parameters for Worker Inhalation Ex
josure Concentrations During Metal
Ro
w
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration (mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall Confidence
Rating from Data
Extraction and
Evaluation
Rationale for
Inclusion /
Exclusion
Unknown - Per source, the
50th percentile: below
sampling time greater than or
Excluded - This
1
Unknown
application
type
Area
Unknown application
type. Unknown area of
sampling.
analytical quantification
limitb
90 th percentile: 15.8
95th percentile: 21.1
11
Unknown
equal to 1 hour and exposure
time is greater than or equal to 6
hours, such that this is
comparable to a shift
measurement
(IF A,
2010)
4271620 - 134
Unacceptable
sample does not
indicate the type of
application or
sample time
Unknown - Per source, the
2
Unknown
application
type
Personal
Unknown application
type. Unknown area of
sampling. Samples were
taken in the presence of
LEV.
50th percentile: below
analytical quantification b
90th percentile: 0.6
95th percentile: 0.75
10
Unknown
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to 6
hours, such that this is
comparable to a shift
measurement
(IF A,
2010)
4271620 - 152
Unacceptable
Excluded - This
sample does not
indicate the type of
application or
sample time
Industry listed as
3
Unknown
application
type
Unknown
"manufacture and
processing of metals."
Work group area listed as
"surface coating,
painting." Unknown
application type.
Unknown area of
50th percentile: 0.7
90thpercentile: 3.86
95th percentile: 5.415
37
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure
time is greater than or equal to 6
hours, such that this is
comparable to a shift
measurement
(IF A,
2010)
4271620 - 153
Medium
Excluded - This
sample does not
indicate the type of
application nor
sample time
sampling. No additional
details are provided.
Industry listed as
"manufacture and
Unknown - Per source, the
processing of metals."
sampling time greater than or
Excluded - This
4
Unknown
application
type
Unknown
Work group area listed as
"cleaning." Unknown
application type.
Unknown area of
sampling. No additional
details are provided.
50th percentile: 1.5
90th percentile: 57
95th percentile: 96.4
14
Unknown
equal to 1 hour and exposure
time is greater than or equal to 6
hours, such that this is
comparable to a shift
measurement
(IF A,
2010)
4271620 - 154
Medium
sample does not
indicate the type of
application nor
sample time
5
Dip application
Modeled using
EasyTRA model
Dip application of
substrate into NMP-
containing solution
4.13
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 117
High
Excluded - dip
cleaning data for
NMP is used as
surrogate for this
scenario
6
Dip application
Modeled using
EasyTRA model
Dip application of
substrate into NMP-
containing solution
12.4
Not applicable
- this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 117
High
Excluded - dip
cleaning data for
NMP is used as
surrogate for this
scenario
7
Brash / Roller
Application
Modeled using
EasyTRA model
Roll/brush application of
NMP-containing solution
4.13
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 115
High
Included as PBPK
input for roller /
brash application
Finishing
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Ro
w
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration (mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall Confidence
Rating from Data
Extraction and
Evaluation
Rationale for
Inclusion /
Exclusion
8
Spray
application
Modeled using
Stoffeninanager model
Spray application of
NMP-containing solution.
With spray booth.
7.96
Not applicable
- this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 113
High
Excluded - NMP
monitoring data for
application of
coatings is used as
surrogate for this
scenario
9
Spray
application
Modeled using
Stoffeninanager model
Spray application of
NMP-containing solution.
Without spray booth.
18.7
Not applicable
- this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 113
High
Excluded - NMP
monitoring data for
application of
coatings is used as
surrogate for this
scenario
Statistics were calculated by the cited source and are presented here as they were presented in the source.
This analytical quantification limit is 0.42 mg/m3 (IFA. 2010)
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A.6 Removal of Paints, Coatings, Adhesives, and Sealants
Table Apx A-5 shows all inhalation monitoring data for NMP-based paint and coating removal that
EPA compiled from published literature sources, including 8-hour TWA, short-term, and partial shift
sampling results. In addition to personal monitoring data, EPA summarized modeled inhalation exposure
concentrations from the RIVM Annex XVProposal for a Restriction - NMP report (R1V ). These
exposure concentrations were modeled using the EasyTRA model, which is based on the European
Center for Ecotoxicology and Toxicology of Chemicals (ECETOC) Targeted Risk Assessment (TRA)
tool, and the Stoffenmanager risk assessment software. The ECHA report modeled potential inhalation
exposures during generic application scenarios, specifically the dip, roll/brush, and spray application of
formulations containing NMP. These modeled inhalation exposure concentrations are presented in Rows
22 to 26 of Table_Apx A-5.
The available data does not always distinguish the specific circumstances and industries in which paint
and coating removal occurs; however, these data customarily identify graffiti removal separately from
other paint and coating removal activities. Note that, where the literature source did not specify the
industry or location of the removal activities, EPA includes these data in the miscellaneous paint,
coating, adhesive, and sealant removal category.
Rows 1-8 were translated into 1-hour TWA values, from which low, mean, and high-end values were
calculated for inputs into the PBPK model. Rows 9 and 10 were used for 8-hour TWA inputs into the
PBPK model for paint stripping. Rows 11-15 were not considered in the risk evaluation because the
sample times are unknown or are not representative of the assessed exposure durations.
For graffiti removal, the data in Row 19 were used as 8-hour TWA inputs into the PBPK model. The
data in Rows 17 and 18 were not used because the results fall within the range in Row 19. Row 16, 21,
and 22 were not used because the sample time is not representative of the assessed exposure durations.
Rows 22 - 26 were not used because actual data are favorable to modeled data.
The Department of Defense (DoD) provided monitoring data from its Defense Occupational and
Environmental Health Readiness System - Industrial Hygiene (DOEHRS-IH), which collects
occupational and environmental health risk data from each service branch (DOEHRS-IH. 2018). These
data are included in Rows 27 and 28. These measurements all appear to be task-based samples; however,
the work shift duration for workers performing the monitored activities is reported to be eight hours. The
DOD NMP samples were taken during the removal of coatings and adhesives, which occur at a weekly
or occasional frequency. Information on whether an activity is repeated during a work shift is not
provided. One data point was provided as a less than value and no metadata were provided with which
to interpret the data point (i.e., less than values are provided for measurements below the limit of
detection). The overall confidence rating of the DOD data is High; however, the numeric confidence
score is higher than the data from (U.S. EPA. 2015b). indicating lower quality. Therefore, EPA did not
use these data in this risk evaluation.
163
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Peer Review Draft Document. Do not release or distribute.
NMP Airborne
Concentration
(mg/m3)a
Data Identifier
Overall Confidence
Row
Occupational
Exposure Scenario
Type of Sample
Worker Activity or
Sampling Location
Number of
Samples
Type of
Measurement
Sample
Time
Source b
from Data
Extraction and
Evaluation
Rating from Data
Extraction and
Evaluation
Rational for Inclusion /
Exclusion
1
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Application of floor
stripping solution
17.4
1
Short-term
93 minutes
(U.S. EPA. 2015b:
NIOSH. 1998)
3827504 - 104
High
Included in 1-hour PBPK input
summary
2
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Floor stripping
9.3
1
Short-term
48 minutes
(U.S. EPA. 2015b:
NIOSH. 1998)
3827504 - 104
High
Included in 1-hour PBPK input
summary
3
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Floor stripping with
window open
5.7
1
Short-term
64 minutes
(U.S. EPA. 2015b:
NIOSH. 1998)
3827504 - 104
High
Included in 1-hour PBPK input
summary
4
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Application of floor
stripping solution
21.1
1
Short-term
46 minutes
(U.S. EPA. 2015b:
NIOSH. 1998)
3827504 - 104
High
Included in 1-hour PBPK input
summary
5
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Application of floor
stripping solution.
Windows and doors
closed.
12.6
1
Short-term
47 minutes
(U.S. EPA. 2015b:
NIOSH. 1998)
3827504 - 104
High
Included in 1-hour PBPK input
summary
6
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Application of floor
stripping solution.
Windows and doors
closed.
21.1
1
Short-term
52 minutes
(U.S. EPA. 2015b:
NIOSH. 1998)
3827504 - 104
High
Included in 1-hour PBPK input
summary
7
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Application of floor
stripping solution.
Windows and doors
closed.
14.2
1
Short-term
43 minutes
(U.S. EPA. 2015b:
NIOSH. 1998)
3827504 - 104
High
Included in 1-hour PBPK input
summary
8
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Non-Specific Paint
stripping
280
Unknown
Peak
1 hour
(U.S. EPA. 2015b:
RIVM. 2013: EC.
2007: WHO. 2001)
3827504 - 104
High
Included in 1-hour PBPK input
summary
Miscellaneous paint
Furniture paint
stripping
125 to 167
minutes
(U.S. EPA. 2015b:
Grour). 2012)
Included as the minimum for 8-
9
coating, adhesive, and
sealant removal
Personal
1.0 to 3.8
Unknown
TWA
3827504 - 104
High
hour TWA input summary to
PBPK model
10
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Non-Specific Paint
stripping
64
Unknown
Maximum 8-
hour TWA
8 hours
(U.S. EPA. 2015b:
RIVM. 2013: EC.
2007: WHO. 2001)
3827504 - 105
High
Included in 8-hour TWA input
summary to PBPK model
11
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Brush application of
paint stripper
39
1
Consumer
measurement0
129
minutes
(U.S. EPA. 2015b.
1994)
3827504 - 104
High
Excluded - This short-term
sample is not representative of
the assessed exposure durations
12
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Brush application of
paint stripper
37
1
Consumer
measurement0
130
minutes
(U.S. EPA. 2015b.
1994)
3827504 - 104
High
Excluded - This short-term
sample is not representative of
the assessed exposure durations
13
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Brush application of
paint stripper
37
1
Consumer
measurement0
143
minutes
(U.S. EPA. 2015b.
1994)
3827504 - 104
High
Excluded - This short-term
sample is not representative of
the assessed exposure durations
14
Miscellaneous paint
coating, adhesive, and
sealant removal
Unknown
Non-Specific Paint
stripping with dip
application
0.01 to 6
Unknown
Unknown
Unknown
(U.S. EPA. 2015b:
Grour). 2012)
3827504 - 104
High
Excluded - This short-term
sample is not representative of
the assessed exposure durations
15
Miscellaneous paint
coating, adhesive, and
sealant removal
Unknown
Non-Specific Paint
stripping
0.82 to 4.1
Unknown
Unknown
Unknown
(RIVM. 2013: Will
et al.. 2004)
3827504 - 104
High
Excluded - This short-term
sample is not representative of
the assessed exposure durations
and Sealants
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Row
Occupational
Exposure Scenario
Type of Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample
Time
Source b
Data Identifier
from Data
Extraction and
Evaluation
Overall Confidence
Rating from Data
Extraction and
Evaluation
Rational for Inclusion /
Exclusion
16
Graffiti removal
Unknown
Graffiti removal -
Unknown worker
activities or conditions
0.01 to 30
Unknown
Unknown
Unknown
(U.S. EPA. 2015b:
Grout). 2012)
3827504 - 104
High
Excluded - This short-term
sample is not representative of
the assessed exposure durations
17
Graffiti removal
Personal
Graffiti removal in
poorly ventilated,
partially enclosed
spaces
Range: 0 to 1.68
Geometric mean:
0.4
Mean: 0.56
Unknown (data
for 6 workers)
8-hour TWA
8 hours
(U.S. EPA. 2015b:
Anundi et al.. 2000)
3827504 - 106
High
Excluded - this sample set falls
within the range used from Row
19
18
Graffiti removal
Personal
Graffiti removal in
poorly ventilated,
partially enclosed
spaces
Range: 0.61 to 2.56
Geometric mean:
1.5
Mean: 1.78
Unknown (data
for 3 workers)
8-hour TWA
8 hours
(U.S. EPA. 2015b:
Anundi et al.. 2000)
3827504 - 106
High
Excluded - this sample set falls
within the range used from Row
19
19
Graffiti removal
Personal
Graffiti removal in
poorly ventilated,
partially enclosed
spaces
Range: 0.03 to 4.52
Geometric mean:
0.67
Mean: 1
Unknown (data
for 25 workers)
8-hour TWA
8 hours
(U.S. EPA. 2015b:
Anundi et al.. 2000)
3827504 - 103
High
Included - this sample set has
the highest range for graffiti
removal thus is used for 8-hour
TWA PBPK inputs
Range: 0.01 to
20
Graffiti removal
Personal
Graffiti removal in
poorly ventilated,
partially enclosed
spaces
24.61
Geometric mean:
1.97
Mean: 4.71
Standard deviation:
6.17
Unknown (data
for 40 workers)
Short-term
15 minutes
(U.S. EPA. 2015b:
Anundi et al.. 2000)
3827504 - 107
High
Excluded - This short-term
sample is not representative of
the assessed time frames
21
Graffiti removal
Personal
Graffiti removal in
partially enclosed
spaces
9.9
1
Short-term
15 minutes
(U.S. EPA. 2015b:
Anundi et al.. 1993)
3827504 - 107
High
Excluded - This short-term
sample is not representative of
the assessed time frames
22
Miscellaneous paint
coating, adhesive, and
sealant removal
Modeled using EasyTRA model
Dip application of
substrate into NMP-
containing solution
4.13
Not applicable -
this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 117
High
Excluded - Monitoring data is
used over modeled data
23
Miscellaneous paint
coating, adhesive, and
sealant removal
Modeled using EasyTRA model
Dip application of
substrate into NMP-
containing solution
12.4
Not applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM. 2013)
3809440 - 117
High
Excluded - Monitoring data is
used over modeled data
24
Miscellaneous paint
coating, adhesive, and
sealant removal
Modeled using EasyTRA model
Roll/brush application
of NMP-containing
solution
4.13
Not applicable -
this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM. 2013)
3809440 - 115
High
Excluded - Monitoring data is
used over modeled data
25
Miscellaneous paint
coating, adhesive, and
sealant removal
Modeled using Stoffemnanager model
Spray application of
NMP-containing
solution. With spray
booth.
7.96
Not applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM. 2013)
3809440 - 113
High
Excluded - Monitoring data is
used over modeled data
26
Miscellaneous paint
coating, adhesive, and
sealant removal
Modeled using Stoffemnanager model
Spray application of
NMP-containing
solution. Without
spray booth.
18.7
Not applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM. 2013)
3809440 - 113
High
Excluded - Monitoring data is
used over modeled data
27
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Using Safe Strip to
Remove Plastic
Covering
<15.2
1
Short-term
17 minutes
(DOEHRS-IH.
2018)
5178607 - 103
High
Excluded - Air concentration is
a less than value and no
metadata were provided to
interpret this value
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Row
Occupational
Exposure Scenario
Type of Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample
Time
Source b
Data Identifier
from Data
Extraction and
Evaluation
Overall Confidence
Rating from Data
Extraction and
Evaluation
Rational for Inclusion /
Exclusion
28
Miscellaneous paint
coating, adhesive, and
sealant removal
Personal
Glue removal
11
1
Short-term
78 minutes
(DOEHRS-IH.
2018)
5178607 - 104
High
Excluded - These data have a
lower confidence score than the
data from (U.S. EPA. 2015b)
a - Statistics were calculated by the cited source and are presented here as they were presented in the source.
b - Where information is presented in multiple sources all sources are listed. Information was not combined from these sources but was presented in all sources independently,
c - Consumer measurements may be used as surrogate for occupational exposures.
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A.7 Application of Paints, Coatings, Adhesives, and Sealants
TableApx A-6 shows inhalation monitoring data that are available in published literature for NMP-
based paints, coatings, adhesives and sealants. In addition to personal monitoring data, EPA summarized
modeled inhalation exposure concentrations from the RIVM Annex XV Proposal for a Restriction -
NMP report (RIVM. 2.013). These exposure concentrations were modeled using the EasyTRA model,
which is based on the European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC)
Targeted Risk Assessment (TRA) tool, and the Stoffenmanager risk assessment software. The RIVM
Annex XV Proposal for a Restriction - NMP report modeled potential inhalation exposures during
generic application scenarios, specifically the dip, roll/brush, and spray application of formulations
containing NMP. These modeled inhalation exposure concentrations are presented in Rows 19 to 23 of
Table Apx A-6.
In the study by NIOSH, presented in Rows 1-9, samples were taken over two 3.5-hour periods (7 am to
10:30 am and 10:30 am to 2 pm) (totaling 7 hours per day for each monitored worker) (NIOSH. 1998).
Since the NIOSH study authors did not assemble the two 3.5-hour samples for each worker together into
a single 7-hour TWA exposure, nor provide the 3.5-hour TWA exposures for each unique worker, EPA
assumed the distribution of exposures for a given worker in the first half of their shift is equal to the
distribution of exposures in the second-half of their shift. Therefore, the 3.5-hour TWA exposure in the
first-half of the shift equals the 3.5-hour TWA exposure in the second-half of the shift, which is also
equal to the 7-hour TWA exposure.
Further, for spray application, EPA uses the data in Row 1 to represent potential inhalation exposure to
workers. EPA translated these data into 4-hour TWA values by assuming no exposure during the
remaining half hour in the 4 hour exposure duration. EPA translated these data into 8-hour TWA values
by assuming workers are exposed to the concentrations in Row 1 for 7 hours, as described above, and
have no exposure for the remaining 1 hour.
EPA did not use the data in Rows 3 to 5 because of the smaller sample size and the potential for the
same workers to be captured in the sample results presented in Row 1. EPA did not use the data in Rows
6 to 11 because these are area samples, which are expected to be less representative of worker and ONU
exposures than personal breathing zone samples.
The DoD provided NMP monitoring data taken during spray painting processes that occur at a weekly
frequency (DOEHRS -EH. 2018). These data are included in Rows 24 and 25. Information on whether an
activity is repeated during a work shift is not provided. Additionally, these data were provided as less
than values and no metadata were provided with which to interpret these data (i.e., less than values are
provided for measurements below the limit of detection). Therefore, EPA did not use these data in this
risk evaluation.
Due to lack of personal monitoring data or modeled exposure data for roll coating, EPA assessed
exposures using the EPA/OPPTIIVRoll Coating Inhalation Model, which assumes a low-end
particulate concentration in air of 0.04 mg/m3 and a high-end particulate concentration of 0.26 mg/m3
(( ). To determine the potential worker exposure concentration of NMP, EPA multiplied
these particulate air concentrations by the low, mid-range, and high-end mass fractions of NMP
discussed in Section 2.7.2.3.2. Then, from these six calculated NMP exposure concentrations, EPA
calculated a central tendency (50th percentile) and worst-case (95th percentile) exposure concentration to
be 0.03 and 0.19, respectively. Note that the EPA/OPPT UV Roll Coating Inhalation Model is intended
for assessing potential exposure concentrations to non-volatile portions of mists. Therefore, these
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exposure estimates may underestimate exposure as they do not account for the portion of NMP that
volatilizes. However, NMP's low volatility should mitigate this underestimation.
EPA did not find any personal monitoring data for dip application of paints, coatings, adhesives, and
sealants. The RIVM Annex XV Proposal for a Restriction - NMP report modeled a typical 8-hour TWA
NMP exposure concentration of 4.13 mg/m3 for a generic dip application scenario (see Row 19 of
TableApx A-6) (RIVM. 2013). While EPA did not find monitoring data for dip application of paints,
coatings, adhesives, and sealants containing NMP, EPA did find monitoring data for the dip application
of cleaning products containing NMP. EPA summarized and used these data in Section 2.13. Due to lack
of data for this scenario, EPA used the same central tendency and worst-case values calculated for dip
application of cleaning products in Section 2.13 as surrogate (surrogate work activities using NMP) for
this scenario.
EPA did not find any personal monitoring data for manual brush / roller or syringe / bead application of
paints, coatings, adhesives, and sealants. The RIVM Annex XV Proposal for a Restriction - NMP report
modeled a typical NMP exposure concentration of 4.13 mg/m3 for a generic roller / brush application
scenario (see Row 21 of Table Apx A-6) ( A.. 2013). EPA expects that these two application types
result in similar exposure potential, as neither are expected to produce mists or aerosols, thus the main
inhalation exposure point is the potential worker inhalation exposure to NMP vapors during the
application and drying of paints, coatings, adhesives and sealants. Due to lack of any additional
information, EPA utilizes this value to assess a typical potential worker exposure scenario.
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Table Apx A-6. Summary of Inhalation Monitoring Data for Application of Paints, Coatings, Adhesives, and Sealants
Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
1
Spray
application
Personal
Workers who entered the
paint booths to adjust the
spray guns and/or to change
the air filters.
Range: 0.04 to 5.15
Mean: 0.61 b
26
Short-term
3.5 hours
(NIOSH.
1998)
4287129- 101
High
Included - used to
represent 8-hour TWA
input summary to PBPK
model for spray
application for workers
2
Spray
application
Personal
Workers who did not work
with paint or paint booths.
Range: 0.04 to 0.61
Mean: 0.16 b
19
Short-term
3.5 hours
(NIOSH.
1998)
4287129 - 102
High
Excluded - EPA used the
range of exposures from
Row 1, which is inclusive
of these data
3
Spray
application
Personal
Spray equipment operators
(application done in a spray
booth by worker from
outside of booth).
Range: 0.04 to 0.12
Mean: 0.08 b
3
Short-term
3.5 hours
(NIOSH.
1998)
4287129 - 102
High
Excluded - these workers
are expected to be
included in those samples
for the data set in Row 1
4
Spray
application
Personal
Changing air filters inside a
paint booth.
0.77 b
1
Short-term, for
duration of task
5 minutes
(NIOSH.
1998)
4287129- 101
High
Excluded - This sample
is not representative of
the assessed exposure
durations
5
Spray
application
Personal
Mixing the paint and filling
the paint booth canister.
0.024 b
1
Short-term, for
duration of task
12 minutes
(NIOSH.
1998)
4287129 - 102
High
Excluded - This sample
is not representative of
the assessed exposure
durations
6
Spray
application
Area
Inside paint booth.
Range: 18 to 101
Mean: 49 b
6
Short-term
90 minutes
(NIOSH.
1998)
4287129 - 103
High
Excluded - Personal
samples are used over
area samples
7
Spray
application
Area
Area outside paint booth.
Range: 0.04 to 0.47
Mean: 0.20 b
8
Short-term
90 minutes
(NIOSH.
1998)
4287129 - 104
High
Excluded - Personal
samples are used over
area samples
8
Spray
application
Area
Paint mix area.
Range: 0.16 to 0.81
Mean: 0.41 b
3
Short-term
90 minutes
(NIOSH.
1998)
4287129 - 104
High
Excluded - Personal
samples are used over
area samples
9
Spray
application
Area
Lunch area.
Range: 0.04 to 0.12
Mean: 0.08 b
3
Short-term
90 minutes
(NIOSH.
1998)
4287129 - 104
High
Excluded - Personal
samples are used over
area samples
10
Spray
application
Area
Air concentration of
particulates while using a
conventional air-atomized
spray gun
Particulate
concentration: 2.3
(downdraft) and 15
(cross-draft)
Unknown
Unknown
Unknown
(OECD.
2011)
Not applicable
Not applicable
Excluded - This sample
is not representative of
the assessed exposure
durations
11
Spray
application
Area
Air concentration of
particulates while high
volume-low pressure
(HVLP) spray gun
Particulate
concentration: 1.9
(downdraft) and 15
(cross-draft)
Unknown
Unknown
Unknown
(OECD.
2011)
Not applicable
Not applicable
Excluded - This sample
is not representative of
the assessed exposure
durations
12
Unknown
application type
Area
Unknown paint application
type. Unknown area of
sampling.
50th percentile: 0.2
90th percentile: 0.5
95th percentile: 2.5
12
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure time
is greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 108
Medium
Excluded - This sample
does not indicate the type
of application nor sample
time
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Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
13
unknown
application type
Area
Work group area listed as
"surface coating, painting."
No additional details are
provided.
50th percentile: 0.2
(below analytical
quantification limit of
0.42)
90th percentile: 3
95th percentile: 5.3 5
55
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure time
is greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 131
Medium
Excluded - This sample
does not indicate the type
of application nor sample
time
14
unknown
application type
Personal
Work group area listed as
"surface coating, painting."
No additional details are
provided.
50th percentile: 0.65
90th percentile: 3
95th percentile: 4.865
39
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure time
is greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 138
Medium
Excluded - This sample
does not indicate the type
of application nor sample
time
15
unknown
application type
Unknown
Work group area listed as
"surface coating, painting."
Samples taken in the
absence of LEV. No
additional details are
provided.
50 th percentile:
below analytical
quantification limit of
0.42
90thpercentile: 3.24
95th percentile: 4.055
11
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure time
is greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 142
Medium
Excluded - This sample
does not indicate the type
of application nor sample
time
16
unknown
application type
Unknown
Work group area listed as
"surface coating, painting."
Samples taken in the
presence of LEV. No
additional details are
provided.
50th percentile: 0.3
(below analytical
quantification limit of
0.42)
90th percentile: 3.76
95th percentile: 5.46
68
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure time
is greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IFA. 2010)
4271620 - 149
Medium
Excluded - This sample
does not indicate the type
of application nor sample
time
17
unknown
application type
Personal
Equipment clean up in paint
shop
Mean: 0.53
Maximum: 0.81
3
Unknown
unknown - greater than 5.5 hours
(DuPont.
1990)
4214100-104
Medium
Excluded - data is from
the 1980s and sample
duration is unknown
18
unknown
application type
Personal
Solvent for spray
application of roll coating
Mean: 8.11
Maximum: 12.16
2
Unknown
25 mins
(DuPont.
1990)
4214100-105
Medium
Excluded - data is from
the 1980s
19
Dip application
Modeled using EasyTRA model
Dip application of substrate
into NMP-containing
solution
4.13
Not
applicable -
this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 117
High
Excluded - dip cleaning
data for NMP is used as
surrogate for this scenario
20
Dip application
Modeled using EasyTRA model
Dip application of substrate
into NMP-containing
solution
12.4
Not
applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 117
High
Excluded - dip cleaning
data for NMP is used as
surrogate for this scenario
21
Brash / Roller
Application
Modeled using EasyTRA model
Roll/brash application of
NMP-containing solution
4.13
Not
applicable -
this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 115
High
Included as PBPK input
for roller / brash
application
22
Spray
application
Modeled using Stoffemnanager model
Spray application of NMP-
containing solution. With
spray booth.
7.96
Not
applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 113
High
Excluded - Monitoring
data is used over modeled
data
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Data Identifier
from Data
Extraction and
Evaluation
Overall
Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Confidence
Rating from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
Not
23
Spray
application
Modeled using Stoffemnanager model
Spray application of NMP-
containing solution.
Without spray booth.
18.7
applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 113
High
Excluded - Monitoring
data is used over modeled
data
Excluded - Air
24
Spray
application
Personal
Spray paint tending
<5.08
1
Short-term
50 minutes
(DOEHRS-
IH.2018)
5178607- 101
High
concentration is a less
than value and no
metadata were provided
to interpret this value
Excluded - Air
25
Spray
application
Personal
Spray paint tending
<5.64
1
Short-term
45 minutes
(DOEHRS-
IH.2018)
5178607- 102
High
concentration is a less
than value and no
metadata were provided
to interpret this value
a - Statistics were calculated by the cited source and are presented here as they were presented in the source.
b - Converted from ppm to mg/m3 by multiplying the measurement in ppm by the molecular weight of NMP (99.133 g/mol) and dividing by molar volume (24.45 L).
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A.8 Electronic Parts Manufacturing
EPA reviewed the assessment of exposures for workers in the electronics manufacturing industry that
was presented in the RIVM Annex XVProposal for a Restriction - NMP report (RIVM. ). This
report does not assess the use of NMP for cleaning in the electronics industries separately from other
cleaning occupational exposure scenarios. The report additionally does not assess battery manufacturing
separately from other coatings occupational exposure scenarios. EPA assessed exposures to NMP in the
electronics manufacturing industry distinctly, due to the potential differences in processes and
engineering controls at electronics manufacturing sites over other sites that perform cleaning and coating
activities using NMP-based products.
TableApx A-8 shows inhalation monitoring data that are available in published literature for the use of
NMP in the electronics manufacturing industries. Rows 1 through 5 present data compiled by the
German Institute for Occupational Safety and Health ( 10). These data are categorized as being
within the industry categories of electrical engineering, fine mechanics, and optics, which are classified
as conducting surface coating and cleaning activities. The specific worker activities associated with the
presented data are unknown. EPA therefore does not use these data.
The data presented in Rows 6 and 7 are from a study conducted by Beaulieu and Schmerber (1991) on
the use of NMP in the microelectronics fabrication industry. The data in Row 7 represents the area air
concentration of NMP when NMP is used at elevated temperatures (80°C). This sample is not expected
to be representative of worker exposures because it is not a personal breathing zone sample and because
current industry information indicates that processes are frequently totally or partially enclosed and
equipped with ventilation that reduces the potential for worker exposures (Saft, 2 ; Roberts. 2017;
RIVM. 20131
The data provided in Rows 8 through 11 were provided in a public comment by the Semiconductor
Industry Association (SIA) (SIA. 2017). These data were originally provided by the European
Semiconductor Industry Association to the EU commission and ECHA for consideration in the RIVM
Annex XV Proposal for a Restriction - NMP report (RIVM. 2013) and were collected at various
semiconductor fabrication facilities between 2003 and 2012. These samples were taken in worker
personal breathing zones.
SIA provided an additional data submission to EPA in 2019 (S ). These data are presented in
Rows 12 through 22. These data are 8-hour and 12-hour TWA values for personal breathing zone
samples of workers involved in handing and changeout of containers, photolithography operations,
maintenance activities, virgin (100%) NMP unloading, and waste NMP (92%) loading. In addition, the
SIA data contains 8-hour and 12-hour TWA area samples taken in the fabrication area. EPA calculated
central tendency and high-end values for this dataset, for each task and 8-hour and 12-hour TWA values.
The majority (i.e., 96% of all sample results) of samples were non-detect for NMP. Where non-detect
values were included in the dataset, EPA calculated the limit of detection (LOD) divided by two. EPA
used this method for approximating a concentration for non-detect samples because the geometric
standard deviation of the dataset is greater than three (EPA. 1994). Because greater than 50% of the
monitoring data results are non-detect for NMP, the use of the LOD/2 for the calculation of statistics
will results in potentially biased estimates. However, no other methods to address the reporting limit of
detection exist (EPA. 1994).
EPA calculated the central tendency and high-end values listed in Table Apx A-7, using the LOD/2 for
sample results that were non-detect for NMP. EPA used the SIA (SIA. 2019a) data to evaluate inhalation
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exposures for this scenario. EPA used these data in place of the 2017 data submitted by SIA (SIA.
2017V The SIA (SIA. 2019a) data was rated as High overall confidence compared to the previous SIA
data, which was rated Medium. Additionally, the SIA (SIA. 2019a) data represents the same worker
activities as those in the previous SIA submission, as well as a few additional worker activities.
Specifically, using the SIA (SIA. 2019a) data, EPA used the calculated 12-hour TWA central tendency
(50th percentile) and high-end (95th percentile) values as inputs in the PBPK modeling. EPA used the 12-
hour TWA data because there are more sample results for 12-hour shifts, indicating this is the more
frequent shift length for this industry. EPA used these 12-hour TWA values in conjunction with dermal
parameters for the PBK modeling. Note that EPA used updated NMP concentration values provided in
the SIA (SIA. 2019a) data set to calculate the central tendency and high-end NMP concentration that
workers may be dermally exposed to.
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Table Apx A-7. Summary of SIA Data SIA (SIA, 2019a)
8-hour TWA
12-hour TWA
Central
High-
Central
Task
Number of
samples
Non-
detects
Count
Tendency
(mg/m3)
End
(mg/m3)
Count
Tendency
(mg/m3)
High-End
(mg/m3)
notes
Container
handling, small
containers
19
19
5
0.026
0.243
14
0.507
0.608
8-hr: 50th percentile presented as central
tendency and maximum value presented as
high end
12-hr: 50th percentile presented as central
tendency and 95th percentile presented as
high end
Container
handling, drums
15
15
5
0.026
0.026
10
0.013
1.544
8-hr: 50th percentile presented as central
tendency and maximum value presented as
high end
12-hr: 50th percentile presented as central
tendency and 95th percentile presented as
high end
Fab worker
28
28
0
N/A
28
0.138
0.405
12-hr: 50th percentile presented as central
tendency and 95th percentile presented as
high end
Maintenance
45
41
9
0.026
0.726
36
0.020
0.690
8-hr and 12-hr: 50th percentile presented as
central tendency and 95th percentile
presented as high end
Fab area samples
9
9
2
0.026
0.026
7
0.162
0.284
8-hr: Central tendency is the midpoint value
between the two data points; high end is the
higher of the two values
12-hr: 50th percentile presented as central
tendency and 95th percentile presented as
high end
Virgin NMP truck
unloading
1
0
1
4.78
0
N/A
Single 8-hr TWA value available
Waste truck
loading
1
1
1
0.709
0
N/A
Single 8-hr TWA value available
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Table Apx A-8. Summary of Worker Inhalation Exposure Concentrations During Electronics Manufacturing
Row
Occupational
Exposure Scenario
Type of
Sample
Worker Activity or Sampling Location
NMP Airborne
Concentration
(mg/m3)a
Number
of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence Rating
from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
50th percentile: 0.3
Unknown - Per source, the
1
Electrical
engineering, fine
mechanics, optics
Area
Unknown activities within electrical
engineering, fine mechanics, and optics
manufacturing. Likely includes both cleaning
and surface coatings activities.
(below analytical
quantification limit of
0.42)
90thpercentile: 3.54
95th percentile: 6.2
44
Unknown
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IF A,
2010)
4271620 - 106
Medium
Excluded - conditions of use
and sample time are unknown
50th percentile: below
Unknown - Per source, the
2
Electrical
engineering, fine
mechanics, optics
Personal
Unknown activities within electrical
engineering, fine mechanics, and optics
manufacturing. Likely includes both cleaning
and surface coatings activities.
analytical
quantification limit of
0.42
90th percentile: 9.6
95th percentile: 11.9
21
Unknown
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IF A,
2010)
4271620- 113
Medium
Excluded - conditions of use
and sample time are unknown
3
Electrical
engineering, fine
mechanics, optics
Unknown
Unknown activities within electrical
engineering, fine mechanics, and optics
manufacturing. Likely includes both cleaning
and surface coatings activities. Samples taken
at facilities with LEV.
50th percentile: 0.2
(below analytical
quantification limit of
0.42)
90th percentile: 3
95thpercentile: 3.9
40
Unknown
Unknown - Per source, the
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IF A,
2010)
4271620 - 121
Medium
Excluded - conditions of use
and sample time are unknown
50th percentile: 0.2
Unknown - Per source, the
4
Electrical
engineering, fine
mechanics, optics
Unknown
Listed as "surface coating, painting" within
electrical engineering, fine mechanics, and
optics manufacturing. Additional details are
not provided.
(below analytical
quantification limit of
0.42)
90 th percentile: 1.22
95th percentile: 1.965
21
Unknown
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IF A,
2010)
4271620 - 157
Medium
Excluded - conditions of use
and sample time are unknown
Unknown - Per source, the
5
Electrical
engineering, fine
mechanics, optics
Unknown
Listed as "cleaning" within electrical
engineering, fine mechanics, and optics
manufacturing. Additional details are not
provided.
50th percentile: 0.95
90 th percentile: 11.9
95th percentile: 12
21
Unknown
sampling time greater than or equal
to 1 hour and exposure time is
greater than or equal to 6 hours,
such that this is comparable to a
shift measurement
(IF A,
2010)
4271620 - 158
Medium
Excluded - conditions of use
and sample time are unknown
(EC.
Excluded - this sample is from a
f.
Microelectronics
Personal
Unknown - workers in the microelectronics
Up to 6 mg/m3
Unknown
8-hour TWA
8 hours
2007;
3809476 - 102
Low
1991 study and may not be
fabrication
fabrication industry
WHO,
2001)
representative of current
industry conditions
1
Microelectronics
fabrication
Area
Unknown - workers in the microelectronics
fabrication industry when warm NMP (80°C)
was being handled
Up to 280 mg/m3
(NMP at a temperature
of 80°C)
Unknown
Full-shift
Unknown
(EC.
2007;
WHO,
2001)
3809476 - 103
Low
Excluded - this sample is from a
1991 study and may not be
representative of current
industry conditions
8
Wafer stripping and
removing processes
Personal
Wafer stripping ('cleaning') removing
photoresist. Wafer cleaning for organics
removal. Operations are in a closed processing
system.
Range: less than the
detection limit to 0.202
Unknown
Unknown -
likely full-shift
Unknown
(SI A,
2017)
5176409 - 101
Medium
Excluded - EPA used updated
data from SI A (SI A. 2019a)
included below
9
Deposition
processes
Personal
Photolithography layer spin-on. Polyimide
deposition. Operations are in a closed
processing system.
Range: 0.0247 to 0.857
Unknown
Unknown -
likely full-shift
Unknown
(SI A,
2017)
5176409 - 102
Medium
Excluded - EPA used updated
data from SI A (SI A. 2019a)
included below
10
Maintenance
Personal
Preventive maintenance at process equipment
tools in the cleanroom. Invasive maintenance.
Range: less than the
detection limit to 0.770
Unknown
Unknown -
likely full-shift
Unknown
(SI A,
2017)
5176409 - 103
Medium
Excluded - EPA used updated
data from SI A (SI A. 2019a)
included below
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Row
Occupational
Exposure Scenario
Type of
Sample
Worker Activity or Sampling Location
NMP Airborne
Concentration
(mg/m3)a
Number
of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence Rating
from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
11
Chemical storage
and handling
Personal
Chemicals storage and delivery areas open to
ambient air. Canister, bottle and container
change at tools and chemfill stations not in the
cleanroom.
Range: less than the
detection limit to 4.054
Unknown
Unknown -
likely full-shift
Unknown
(SI A,
2017)
5176409 - 104
Medium
Excluded - EPA used updated
data from SI A (SI A. 2019a)
included below
12
Container handling
Personal
Container handling, small containers: 5-gallon
to 20L
0.0263 - 0.243 (all
samples are non-detect;
values presented are
LOD/2)
5
8-hr TWA
8-hour TWA
(SI A,
2019a)
5161295 - 101 to
105
High
Included - EPA used these data
to estimate occupational
exposures
13
Container handling
Personal
Container handling, small containers: 5-gallon
to 20L
0.162-0.608 (all
samples are non-detect;
values presented are
LOD/2)
14
12-hr TWA
12-hour TWA
(SI A,
2019a)
5161295 - 101 to
105
High
Included - EPA used these data
to estimate occupational
exposures
14
Container handling
Personal
Container handling, changeout: 5 5-gallon drum
0.0263 (all samples are
non-detect; value
presented is LOD/2)
5
8-hr TWA
8-hr TWA
(SI A,
2019a)
5161295 - 101 to
105
High
Included - EPA used these data
to estimate occupational
exposures
15
Container handling
Personal
Container handling, changeout: 55-gallon drum
0.0020 - 1.544 (all
samples are non-detect;
values presented are
LOD/2)
10
12-hr TWA
12-hour TWA
(SI A,
2019a)
5161295 - 101 to
105
High
Included - EPA used these data
to estimate occupational
exposures
16
Microelectronics
fabrication
Personal
Fab worker: Photolithography maintenance,
production operator, routine operator, wet
station operator
0.0067 - 0.405 (all
samples are non-detect;
values presented are
LOD/2)
28
12-hr TWA
12-hour TWA
(SI A,
2019a)
5161295 - 110
High
Included - EPA used these data
to estimate occupational
exposures
17
Maintenance
area
Maintenance activities: filter changeout,
cleaning, preventative maintenance
0.00608 -0.750 (8 of 9
samples are non-detect;
values presented are
LOD/2)
9
8-hr TWA
8-hr TWA
(SI A,
2019a)
5161295 - 106 to
109
High
Included - EPA used these data
to estimate occupational
exposures
18
Maintenance
Area
Maintenance activities: filter changeout,
cleaning, preventative maintenance
0.0020 - 1.544 (33 of
36 samples are non-
detect; values presented
are LOD/2)
36
12-hr TWA
12-hour TWA
(SI A,
2019a)
5161295 - 106 to
109
High
Included - EPA used these data
to estimate occupational
exposures
19
Fabrication area
Personal
Fab area samples: photolithography, polyimide
cure oven, wet area
0.0263 (all samples are
non-detect; value
presented is LOD/2)
2
8-hr TWA
8-hr TWA
(SI A,
2019a)
5161295 - 111
High
Excluded - EPA used personal
breathing zone samples to
estimate occupational exposures
and did assess risk from ONU
exposures for this scenario
20
Fabrication area
Personal
Fab area samples: photolithography, polyimide
cure oven, wet area
0.130 -0.284 (all
samples are non-detect;
values presented are
LOD/2)
7
12-hr TWA
12-hour TWA
(SI A,
2019a)
5161295 - 111
High
Excluded - EPA used personal
breathing zone samples to
estimate exposures
21
Virgin NMP
unloading
Personal
Virgin NMP truck off-loading: Pull 6 samples
for purity analysis; transfer of virgin NMP
from a 10,000-gallon tanker truck to a 10,000-
gallon tank in the tank farm. Turn on pump;
stay in enclosure upstairs during ~ 2-hour
transfer.
4.78
1
8-hr TWA
8-hr TWA
(SI A,
2019a)
5161295 - 113
High
Included - EPA used these data
to estimate occupational
exposures
22
Waste NMP loading
Personal
Waste truck loading: Transfer of
approximately 5,000 gallons of NMP waste
from a 10,000-gallon tank to a tanker truck.
0.709 (sample is non-
detect; value presented
is LOD/2)
1
8-hr TWA
8-hr TWA
(SI A,
2019a)
5161295 - 112
High
Included - EPA used these data
to estimate occupational
exposures
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- Statistics were calculated by the cited source and are presented here as they were presented in the source.
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A.9 Printing and Writing
EPA identified one source containing NMP monitoring data at a screen printing shop. However, this
data is presented without any context. This data is presented in Row 1 of Table Apx A-9 and is from a
facility that conducts screen printing, but the sample type, sample duration, and associated worker
activities are unknown, thus the data is not used in this risk evaluation.
The data in Rows 2 through 10 are from a compilation of monitoring data by the German Institute for
Occupational Safety and Health (IFA). These data are listed as "woodworking, paper, and printing
industry" (il A 1:0] 0). EPA is unsure how NMP is used at the companies that fall within this industry
category, as no worker activities or sampling areas are described. Additionally, no sample times are
provided in this compilation. Therefore, EPA excluded these data in this risk evaluation.
No other personal monitoring data on the use of NMP-based inks was found. Due to this lack of data,
EPA assessed potential inhalation exposures during this scenario using data from NIOSH study on ink
mist exposures at a printing shop (Belanger and Cove. 1983). The printing shop did not specifically use
NMP-based inks; thus, this study did not monitor for NMP, but rather for ink mists in worker breathing
zones. EPA used this ink mist data as surrogate and assumed likely NMP concentrations based on the
concentrations of NMP identified in current products described in Section 2.6. The NIOSH study and
EPA methodology for using the study results are described further below.
NIOSH conducted sampling at a newspaper printing plant in 1983 (Belanger and Cc >3.)- This
printing plant operated five printing presses continuously for 24 hours per day. Specifically, NIOSH
conducted personal breathing zone sampling of multiple workers, including printing press operators and
assistants, for ink mist. This study consisted of 43 full shift samples, ranging from around 5 to 8 hours,
and 5 partial shift samples, all between 3 and 4 hours. These data are summarized in Row 11. EPA
translated these sample results into 8-hour TWA and 4-hour TWA concentrations, respectively, by
assuming that exposure concentration is zero for the time remaining in the 8 and 4 hour durations. EPA
then multiplied these ink mist air concentrations by the identified low-end, mean, and high-end weight
fractions of NMP in ink. EPA identified products that range from 1 to 10 weight percent NMP, with a
mean NMP concentration of 6.3 weight percent, as described in Section 2.6. From the calculated air
concentrations, EPA then calculated central tendency (50th percentile) and worst-case (95th percentile)
from these TWA values.
EPA did not find monitoring data on the use of markers or other writing instruments containing NMP.
One assessment performed by Australia's National Industrial Chemicals Notification and Assessment
Scheme (NICNAS) on the use of consumer products indicates that inhalation exposure from the use of
writing inks is assumed negligible due to the small amount of ink, and therefore NMP, used (Australian
Government Department of Health. 2016). In addition, the one writing product identified in the
"Preliminary Information on Manufacturing, Processing, Distribution, Use, and Disposal: NMP"
document and 2017 market profile for NMP indicate that the marker is a weather-resistant (Abt. 2017;
017b). The SDS for this product confirms that the marker is weather-resistant and intended
for use on polyurethane tags / labels
(http://www.markal.eom/assets/l/7/aw plastic eartae white medtip.pdf). Because, this product is
weather-resistant, EPA expects that the primary users will use this product outside, which mitigates the
potential for inhalation exposures.
Consistent with the NICNAS assessment approach and the outdoor use of the identified writing product
containing NMP, EPA does not assess inhalation exposures during use of NMP writing inks.
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Row
Occupational
Exposure
Scenario
Type of
Sample
Worker Activity or Sampling
Location
NMP Airborne Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall Confidence
Rating from Data
Extraction and
Evaluation
Rationale for Inclusion / Exclusion
1
Screen printing
Unknown
Unknown
7.1 to 22.2
Unknown
Unknown
Unknown
(RIVM.
2013)
3809440 - 119
Unacceptable
Excluded - Sample time and measurement
types unknown
2
Unknown
Area
Listed as "woodworking,
paper, printing"
50th percentile: below analytical
quantification limitb
90th percentile: 1
95th percentile: 1.7
40
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
that this is comparable
to a shift measurement
(IFA. 2010)
4271620 - 107
Medium
Excluded - sample times and conditions of
use are unknown
3
Unknown
Area
Listed as "woodworking,
paper, printing"
50th percentile: below analytical
quantification limitb
90th percentile: 6.76
95th percentile: 26
28
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
that this is comparable
to a shift measurement
(IFA. 2010)
4271620 - 163
Medium
Excluded - sample times and conditions of
use are unknown
4
Unknown
Personal
Listed as "woodworking,
paper, printing"
50th percentile: below analytical
quantification limitb
90 th percentile: 12.56
95th percentile: 120.6
14
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
that this is comparable
to a shift measurement
(IFA. 2010)
4271620 - 164
Medium
Excluded - sample times and conditions of
use are unknown
5
Unknown
Personal
Listed as "woodworking,
paper, printing"
50th percentile: below analytical
quantification limitb
90thpercentile: 3.2
95th percentile: 12.8
39
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
that this is comparable
to a shift measurement
(IFA. 2010)
4271620 - 114
Medium
Excluded - sample times and conditions of
use are unknown
6
Unknown
Unknown
Listed as "woodworking,
paper, printing". Taken in the
presence of LEV.
50th percentile: below analytical
quantification limitb
90th percentile: 1
95th percentile: 3.86
33
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
that this is comparable
to a shift measurement
(IFA. 2010)
4271620 - 122
Medium
Excluded - sample times and conditions of
use are unknown
7
Unknown
Unknown
Listed as "woodworking,
paper, printing". Taken in the
presence of LEV.
50th percentile: below analytical
quantification limitb
90th percentile: 2.35
95th percentile: 3
45
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
(IFA. 2010)
4271620 - 123
Medium
Excluded - sample times and conditions of
use are unknown
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Row
Occupational
Exposure
Scenario
Type of
Sample
Worker Activity or Sampling
Location
NMP Airborne Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall Confidence
Rating from Data
Extraction and
Evaluation
Rationale for Inclusion / Exclusion
that this is comparable
to a shift measurement
8
Unknown
Unknown
Listed as "woodworking,
paper, printing". Taken in the
absence of LEV.
50th percentile: below analytical
quantification limitb
90th percentile: 1.7
95th percentile: 1.74
33
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
that this is comparable
to a shift measurement
(IFA. 2010)
4271620 - 127
Medium
Excluded - sample times and conditions of
use are unknown
9
Unknown
Unknown
Listed as "woodworking,
paper, printing". Taken in the
absence of LEV.
50th percentile: below analytical
quantification limitb
90th percentile: 28
95th percentile: 34
45
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
that this is comparable
to a shift measurement
(IFA. 2010)
4271620 - 128
Medium
Excluded - sample times and conditions of
use are unknown
10
Unknown
Unknown
Listed as "woodworking,
paper, printing". Taken in the
absence of LEV.
50th percentile: below analytical
quantification limit of 0.42
90th percentile: 0.46
95th percentile: 0.95
22
Unknown
Unknown - Per source,
the sampling time
greater than or equal to
1 hour and exposure
time is greater than or
equal to 6 hours, such
that this is comparable
to a shift measurement
(IFA. 2010)
4271620 - 155
Medium
Excluded - sample times and conditions of
use are unknown
11
Unknown
Personal
Multiple different workers
Range: 0.12 to 3.29
48
Partial and Full
Shift
3.3 to 7.9 hours
(Belanser
and Cove.
1983)
3101190 - 101
Medium
Included - individual samples were
translated to 4-hour or 8-hour TWAs
(assuming no exposure for remaining time
in shift), then central tendency and worst-
case were calculated for PBPK inputs
a - Statistics were calculated by the cited source and are presented here as they were presented in the source,
b - This analytical quantification limit is 0.42 mg/m3 (IFA. 2010)
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A. 10 Soldering
EPA did not find inhalation monitoring data specifically related to the use of NMP-based soldering
products. The German Institute for Occupational Safety and Health (IFA) compiled monitoring data for
multiple industries that use NMP, including the machinery manufacturing industry and the building
industry ( 1110). These data are summarized in TableApx A-10.
EPA has not identified information describing how NMP is used within the machinery manufacturing
industry. However, EPA believes that the operations within the machinery manufacturing industry likely
fall into the paint and coatings category, which is assessed in Section 2.5. EPA therefore excludes these
data, presented in Rows 1, 2, 3, 5, and 6, from the assessment of this scenario.
The activities associated with the building industry data presented in Row 4 of Table Apx A-10 are also
unknown, and may include soldering, paint stripping, or any other use of NMP within the building
industry. EPA therefore excludes these data.
Due to lack of additional information and the low NMP content in the one identified soldering
production containing NMP (one to 2.5 weight percent NMP), the potential for worker and ONU
inhalation exposures is likely small. In addition, some of the NMP may be destroyed in the soldering
process, further mitigating the potential for inhalation exposures. Thus, EPA does not assess potential
inhalation exposures during soldering.
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Table Apx A-10. Summary of Inhalation Exposure Concentrations During Soldering
Row
Occupational
Exposure
Scenario
Type of
Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration (mg/m3)a
Number
of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall Confidence
Rating from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
1
Manufacture of
machinery and
vehicles
Area
Unknown activities for the
manufacture of parts for motor
vehicles and engines.
50th percentile: below
analytical quantification
limit of 0.42
90th percentile: 5.02
95th percentile: 7.36
16
Unknown
Unknown - Per source, the sampling time
greater than or equal to 1 hour and exposure
time is greater than or equal to 6 hours, such
that this is comparable to a shift measurement
(IF A,
2010)
4271620 - 105
Medium
Excluded - conditions of
use are unknown; this is
likely related to coatings
application
2
Manufacture of
machinery and
vehicles
Personal
Unknown activities for the
manufacture of parts for motor
vehicles and engines.
50th percentile: 0.3
90th percentile: 1.75
95th percentile: 2.725
15
Unknown
Unknown - Per source, the sampling time
greater than or equal to 1 hour and exposure
time is greater than or equal to 6 hours, such
that this is comparable to a shift measurement
(IF A,
2010)
4271620- 112
Medium
Excluded - conditions of
use are unknown; this is
likely related to coatings
application
3
Manufacture of
machinery and
vehicles
Unknown
Listed as "Steel construction,
manufacture of machinery and
vehicles." Work group listed as
surface coating, painting."
50th percentile: 0.7
90th percentile: 5.56
95th percentile: 7.36
16
Unknown
Unknown - Per source, the sampling time
greater than or equal to 1 hour and exposure
time is greater than or equal to 6 hours, such
that this is comparable to a shift measurement
(IF A,
2010)
4271620 - 156
Medium
Excluded - conditions of
use are unknown; this is
related to coatings
application
4
Building industry
Personal
Unknown activities within the
building industry.
50th percentile: 1.5
90th percentile: 6.6
95th percentile: 7.9
11
Unknown
Unknown - Per source, the sampling time
greater than or equal to 1 hour and exposure
time is greater than or equal to 6 hours, such
that this is comparable to a shift measurement
(IF A,
2010)
4271620- 115
Medium
Excluded - conditions of
use are unknown
5
Manufacture of
machinery and
vehicles
Unknown
Unknown activities for the
manufacture of parts for motor
vehicles and engines.
Taken in presence of LEV.
50th percentile: 0.55
90th percentile: 5.8
95th percentile: 7.45
15
Unknown
Unknown - Per source, the sampling time
greater than or equal to 1 hour and exposure
time is greater than or equal to 6 hours, such
that this is comparable to a shift measurement
(IF A,
2010)
4271620 - 120
Medium
Excluded - conditions of
use are unknown; this is
likely related to coatings
application
6
Manufacture of
machinery and
vehicles
Unknown
Unknown activities for the
manufacture of parts for motor
vehicles and engines.
Taken at facilities without LEV.
All measurements were
below the analytical
quantification limit of 0.42
10
Unknown
Unknown - Per source, the sampling time
greater than or equal to 1 hour and exposure
time is greater than or equal to 6 hours, such
that this is comparable to a shift measurement
(IF A,
2010)
4271620 - 126
Medium
Excluded - conditions of
use are unknown; this is
likely related to coatings
application
a - Statistics were calculated by the cited source and are presented here as they were presented in the source.
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A.ll Commercial Automotive Servicing
EPA did not find monitoring data for the use of NMP products during automotive servicing. Further,
EPA did not find any monitoring data for the use of NMP aerosol products in any industry. To estimate
potential worker inhalation exposures during the use of aerosol products that contain NMP, EPA
modeled potential occupational inhalation exposures for workers and ONUs using EPA's model for
Occupational Exposures during Aerosol Degreasing of Automotive Brakes. This model was used
because EPA does not have related monitoring data nor throughput parameters (i.e., annual and daily
amounts of NMP products used per servicing site). This model includes default parameters for
throughput based on information that CARB obtained from industry surveys of automotive brake
cleaner manufacturers and automotive repair shops.
EPA used the NMP concentrations of the two aerosol degreasing products identified in Section 2.13.1.1
as inputs to the model. The concentrations of these products are 4.5 and 35 to 40 weight percent. The
results of this modeling are near-field and far-field inhalation exposure estimates, which are used as the
input parameters used for the PBPK modeling for workers in and ONUs, respectively. Specifically, EPA
uses the 50th and 95th percentile model results to represent central tendency and worst-case inhalation
exposures, respectively. This model calculates both 8-hour TWA and 1-hour TWA exposure
concentrations.
Table Apx A-ll. Aerosol Degreasing Model Results
Statistic
C(mg/m3)
8-hour TWA
1-hour TWA
Near-field (Worker)
Exposure
Far-field (ONU)
Exposure
Near-field (Worker)
Exposure
Far-field (ONU)
Exposure
Maximum
564.36
128.87
1,504.94
331.33
99th Percentile
72.55
4.20
210.89
12.44
95th Percentile
43.44
1.57
128.76
4.71
50th Percentile
6.39
0.13
19.96
0.40
5th Percentile
0.94
0.01
3.07
0.04
Minimum
0.07
0.00
0.42
0.01
Mean
12.95
0.40
39.13
1.20
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A.l_2_ Laboratory use
Table Apx A-12 shows the inhalation monitoring data that is available in published literature for use of
NMP in a laboratory setting. EPA only found one data source that had inhalation monitoring data, which
is presented in Row 1. This data is for a two-hour exposure duration at a laboratory that uses NMP as a
media in which to dissolve a photoresist formulation for quality testing (Solomon etai. 1996).
Specifically, this sample was taken during the preparation of NMP before use (purification), sample
preparation (dissolving of solid photoresist into NMP), and sample analysis (operating atomic
absorption Spectrophotometer). EPA uses this result as an input into the PBPK model for 2-hour
exposure duration.
In addition to this data point, EPA presented modeled potential inhalation exposures during use of NMP
in industrial and commercial laboratory settings that were included in the RIVM Annex XV Proposal for
a Restriction - NMP report (RIVM. 2013). These modeled exposures are presented in Rows 2 and 3.
RIVM included these modeled exposures in the report due to the lack of actual inhalation monitoring
data for NMP. In lieu of additional monitoring data, EPA uses the modeled exposure concentration in
Row 2 for use of NMP in industrial laboratories with 90 percent efficient LEV as the input into the
PBPK model for a typical full-shift, 8-hour exposure duration. EPA uses the modeled exposure in Row 3
for use of NMP in commercial laboratories with 80 percent efficient LVE as the input for worst-case
full-shift inhalation exposures. EPA uses Row 3 as worst-case because these data relate to commercial
laboratories that use LEV with a lower capture efficiency than those employed by the industrial
laboratories represented in Row 2.
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Table Apx A-12. Summary of Inhalation Monitoring Data for Laboratory Use
Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or Sampling Location
NMP Airborne
Concentration (mg/m3)
Number of Samples
Type of
Measurement
Sample
Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from
Data Extraction
and Evaluation
Rationale for
Inclusion / Exclusion
1
Laboratory use
Source notes that this result
was obtained in both personal
and area samples
Pouring NMP through an ion-exchange column
underpressure (forpurification); sample
preparation and analysis (QC samples of negative
photoresist used in the electronics industry that
were dissolved in NMP)
0.2
Unknown
Partial Shift
2 hours
(Solomon et
al.. 1996)
3043623 - 101
Medium
Included - this
concentration is used
as input into the
PBPK model for a 2
hour exposure
duration
2
Laboratory use
Modeled using EasyTRA
model
Laboratory use in an industrial setting with local
exhaust ventilation (90% efficiency).
2.07
Not applicable - this
is a modeled exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 127
High
Included - this
concentration is used
as input into the
PBPK model for a
typical full-shift
exposure
3
Laboratory use
Modeled using EasyTRA
model
Laboratory use in a commercial setting with local
exhaust ventilation (80% efficiency).
4.13
Not applicable - this
is a modeled exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 127
High
Included - this
concentration is used
as input into the
PBPK model for a
worst-case full-shift
exposure
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A, 13 Cleaning
TableApx A-13 shows inhalation monitoring data that is available in published literature for NMP-
based cleaning products. In addition to personal monitoring data, EPA summarized modeled inhalation
exposure concentrations from the RIVM Annex XV Proposal for a Restriction - NMP report (KIWI,
2013). These exposure concentrations were modeled using the EasyTRA model, which is based on the
European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC) Targeted Risk
Assessment (TRA) tool, and the Stoffenmanager risk assessment software. The ECHA report modeled
potential inhalation exposures during generic application scenarios, specifically the dip, roll/brush, and
spray application of formulations containing NMP. These modeled inhalation exposure concentrations
are presented in Rows 20 to 24 of Table Apx A-13.
The available data do not always distinguish the specific circumstances and industries in which cleaning
activities occur. Note that, where the literature source did not specify the type of cleaning, EPA includes
these data in all cleaning occupational exposure scenarios.
For dip cleaning, EPA calculated 8-hour TWA central tendency (based on 50th percentile) and worst-
case (based on 95th percentile) estimates for using the mean values listed in Rows 1 - 6, 8 - 13, 17, and
20. For spray / wipe cleaning, EPA calculated 8-hour TWA central tendency and worst-case estimates
using the mean values listed in Rows 1-6, 17, and 22. Note, EPA used the modeled exposure for NMP
that is listed in Row 23 as surrogate for wipe cleaning. EPA did not use the data in Rows 7, 14, and 15
because the sample times are unknown. EPA did not use the data in Rows 16, 18, and 19 because the
sample types are area or unknown, which may not be representative of exposures.
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Table Apx A-13. Summary of Inhalation Monitoring Data for Cleaning
Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from Data
Extraction and
Evaluation
Rational for Inclusion /
Exclusion
1
Unknown
Personal
Cleaning of metal parts to
remove resin (unknown cleaner
application type)
Mean: 0.57
Max: 5.24
14
8-hour TWA
8 hours
(Nishimura
et al.. 2009)
735269 - 101
High
Included in 8-hour TWA
input summary to PBPK
model for dip and spray /
wipe cleaning
2
Unknown
Personal
Cleaning of metal parts to
remove resin (unknown cleaner
application type)
Mean: 0.97 b
14
8-hour TWA
8 hours
(Nishimura
et al.. 2009)
735269 - 101
High
Included in 8-hour TWA
input summary to PBPK
model for dip and spray /
wipe cleaning
3
Unknown
Personal
Cleaning of metal parts to
remove resin (unknown cleaner
application type)
Mean: 0.69 b
14
8-hour TWA
8 hours
(Nishimura
et al.. 2009)
735269 - 101
High
Included in 8-hour TWA
input summary to PBPK
model for dip and spray /
wipe cleaning
4
Unknown
Personal
Cleaning of metal parts to
remove resin (unknown cleaner
application type)
Mean: 1.05 b
14
8-hour TWA
8 hours
(Nishimura
et al.. 2009)
735269 - 101
High
Included in 8-hour TWA
input summary to PBPK
model for dip and spray /
wipe cleaning
5
Unknown
Personal
Cleaning of metal parts to
remove resin (unknown cleaner
application type)
Mean: 0.65 b
14
8-hour TWA
8 hours
(Nishimura
et al.. 2009)
735269 - 101
High
Included in 8-hour TWA
input summary to PBPK
model for dip and spray /
wipe cleaning
6
Unknown
Personal
Cleaning of optical and metal
parts (unknown cleaner
application type)
Mean: 2.0
Max: 2.8
12
12-hour TWA
12 hours
(Bader et al..
2006)
3539720 - 101
Medium
Included in 8-hour TWA
input summary to PBPK
model for dip and spray /
wipe cleaning
(RIVM.
2013)
Excluded - This sample
7
Unknown
Unknown
Industrial tank cleaning
Range: 4.1 to 12.4
Unknown
Unknown
Unknown
3809440 - 124
High
is not representative of
the assessed exposure
durations
8
Dip cleaning
Personal
Full-shift sampling for
volunteers who stayed in the
lens cleaning workroom
Range: 0.97 to 1.30
Mean: 1.01 +/- 0.12 b
5 (one per day
for one
worker for a
week)
8-hour TWA
8 hours
(Xiaofei et
al.. 2000)
3562767 - 101
Medium
Included in 8-hour TWA
input summary to PBPK
model for dip cleaning
9
Dip cleaning
Personal
Workers place parts in basket,
put basket in chamber, close
chamber, open chamber,
remove basket and allow
drying in ambient conditions,
transfer basket to washing
process
Range: 1.14 to 2.80
Mean: 1.70 +/- 0.57 b
5 (one per day
for one
worker for a
week)
12-hour TWA
12 hours
(Xiaofei et
al.. 2000)
3562767 - 101
medium
Included in 8-hour TWA
input summary to PBPK
model for dip cleaning
10
Dip cleaning
Personal
Workers place parts in basket,
put basket in chamber, close
chamber, open chamber,
remove basket and allow
drying in ambient conditions,
transfer basket to washing
process
Range: 0.57 to 1.62
Mean: 0.97 +/- 0.36 b
5 (one per day
for one
worker for a
week)
12-hour TWA
12 hours
(Xiaofei et
al.. 2000)
3562767 - 101
medium
Included in 8-hour TWA
input summary to PBPK
model for dip cleaning
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Data Identifier
from Data
Extraction and
Evaluation
Overall
Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Confidence
Rating from Data
Extraction and
Evaluation
Rational for Inclusion /
Exclusion
Workers place parts in basket.
11
Dip cleaning
Personal
put basket in chamber, close
chamber, open chamber,
remove basket and allow
drying in ambient conditions,
transfer basket to washing
process
Range: 0.36 to 0.85
Mean: 0.57+/-0.20 b
5 (one per day
for one
worker for a
week)
12-hour TWA
12 hours
(Xiaofei et
al.. 2000)
3562767 - 101
Medium
Included in 8-hour TWA
input summary to PBPK
model for dip cleaning
Workers place parts in basket.
12
Dip cleaning
Personal
put basket in chamber, close
chamber, open chamber,
remove basket and allow
drying in ambient conditions,
transfer basket to washing
process
Range: 0.97 to 1.14
Mean: 0.77+/-0.24 b
5 (one per day
for one
worker for a
week)
12-hour TWA
12 hours
(Xiaofei et
al.. 2000)
3562767 - 101
Medium
Included in 8-hour TWA
input summary to PBPK
model for dip cleaning
Dip cleaning of metal parts.
13
Dip cleaning
Personal
Workers place parts in basket,
lower basket, life basket when
cleaning complete, and transfer
to water tank
Range: 0.16 to 2.39
Mean: 1.34+/- 0.81b
8
12-hour TWA
12 hours
(Xiaofei et
al.. 2000)
3562767 - 102
medium
Included in 8-hour TWA
input summary to PBPK
model for dip cleaning
Excluded - This sample
14
Dip cleaning
Unknown
Immersion cleaning of metal
parts
Mean: 1.26 b
Unknown
Unknown
Unknown
(BASF.
1993)
3982074 - 101
Low
is not representative of
the assessed exposure
durations
Excluded - This sample
15
Dip cleaning
Unknown
Immersion cleaning of metal
parts
Mean: 7.46 b
Unknown
Unknown
Unknown
(BASF.
1993)
3982074 - 102
Low
is not representative of
the assessed exposure
durations
Unknown - Per source, the
sampling time greater than or
Excluded - Area
Work group area listed as
50th percentile: 0.7
equal to 1 hour and exposure time
samples are not as
16
Unknown
Area
"cleaning." No additional
details are provided.
90 th percentile: 15
95th percentile: 90
30
Unknown
is greater than or equal to 6
hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 132
Medium
representative of
exposures as personal
samples
Unknown - Per source, the
50th percentile: 2
sampling time greater than or
Included in 8-hour TWA
Work group area listed as
90 th percentile:
equal to 1 hour and exposure time
input summary
17
Unknown
Personal
"cleaning." No additional
details are provided.
12.35
95th percentile:
18.875
23
Unknown
is greater than or equal to 6
hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 139
Medium
calculation for PBPK
model for dip and spray /
wipe cleaning
50th percentile: 0.4
Unknown - Per source, the
18
Unknown
Unknown
Work group area listed as
"cleaning." Samples taken in
the absence of LEV. No
additional details are provided.
(below analytical
quantification limit
of 0.42)
11
Unknown
sampling time greater than or
equal to 1 hour and exposure time
is greater than or equal to 6
(IFA. 2010)
4271620 - 143
Medium
Excluded - Unknown
sample type. These data
may not be
90th percentile: 79.6
95th percentile:
102.1
hours, such that this is
comparable to a shift
measurement
representative of
exposures
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Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration
(mg/m3)a
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence
Rating from Data
Extraction and
Evaluation
Rational for Inclusion /
Exclusion
19
Unknown
Unknown
Work group area listed as
"cleaning." Samples taken in
the presence of LEV. No
additional details are provided.
50th percentile: 0.9
90 th percentile:
10.85
95th percentile:
13.125
35
Unknown
Unknown - Per source, the
sampling time greater than or
equal to 1 hour and exposure time
is greater than or equal to 6
hours, such that this is
comparable to a shift
measurement
(IFA. 2010)
4271620 - 150
Medium
Excluded - Unknown
sample type. These data
may not be
representative of
exposures
20
Dip cleaning
Modeled using EasyTRA model
Dip application of substrate
into NMP-containing solution
4.13
Not
applicable -
this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 117
High
Included in 8-hour TWA
input summary
calculation for PBPK
model for dip cleaning
21
Dip cleaning
Modeled using EasyTRA model
Dip application of substrate
into NMP-containing solution
12.4
Not
applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 117
High
Excluded - EPA uses
monitoring data over
modeled data
22
Wipe/spray
Cleaning
Modeled using EasyTRA model
Roll/brush application of
NMP-containing solution
4.13
Not
applicable -
this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 115
High
Included in 8-hour TWA
input summary
calculation for PBPK
model for wipe/spray
cleaning
23
Wipe/spray
Cleaning
Modeled using Stoffemnanager model
Spray application of NMP-
containing solution. With spray
booth.
7.96
Not
applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 113
High
Excluded - EPA uses
monitoring data over
modeled data
24
Wipe/spray
Cleaning
Modeled using Stoffemnanager model
Spray application of NMP-
containing solution. Without
spray booth.
18.7
Not
applicable -
this is a
modeled
exposure
Short-term
4 hours
(RIVM.
2013)
3809440 - 113
High
Excluded - EPA uses
monitoring data over
modeled data
a - Statistics were calculated by the cited source and are presented here as they were presented in the source.
b - Converted fromppmto mg/m3 by multiplying the measurement inppmby the molecular weight of NMP (99.133 g/mol) and dividing by molar volume (24.45 L/mol).
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A. 14 Fertilizer Application
EPA did not find inhalation monitoring data for the application of fertilizers containing NMP. The
RIVM Annex XV Proposal for a Restriction - NMP report presented the modeled potential inhalation
exposures during spray and fog application of agrochemicals (RIVM. ). EPA summarized these
modeled exposures in TableApx A-14. The RIVM Annex XV Proposal for a Restriction - NMP report
recommends that manual application activities should be limited to four hours per shift or less (RIVM.
2013). Application with more automated equipment and separation of the worker from the sources of
exposure can exceed this recommendation. EPA thus assesses both full-shift 8-hour TWA and short-
term 4-hour TWA inhalation exposures. EPA did not find data on short-term exposures.
Due to lack of additional information or modeling approaches, EPA uses the full-shift modeled
exposures from the RIVM Annex XV Proposal for a Restriction - NMP report to represent potential
inhalation exposures during this scenario. Specifically, EPA uses the exposure estimate in Row 1 as a
central tendency inhalation exposure concentration and the estimate in Row 2 as a worst-case inhalation
exposure concentration. These estimates are both full-shift, 8-hour TWA exposures.
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Table Apx A-14. Summary of Worker Inhalation Exposure Concentrations During Fertilizer Application
Row
Occupational
Exposure Scenario
Type of Sample
Worker Activity or Sampling
Location
NMP Airborne
Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample
Time
Source
Data Identifier from
Data Extraction and
Evaluation
Overall Confidence Rating
from Data Extraction and
Evaluation
Rationale for
Inclusion /
Exclusion
1
Spray or fog
application of
agrochemicals
Modeled using EasyTRA model
Spray or fog application of
agrochemicals by a worker located
outside, in a cabin with supplied air.
2.97
Not applicable -
this is a modeled
exposure
8-hour TWA
8 hours
(RIVM
2013)
3809440- 131
High
Included - central
tendency
2
Spray or fog
application of
agrochemicals
Modeled using EasyTRA model
Spray or fog application of
agrochemicals by a worker located
inside without the use of a cabin.
5.27
Not applicable -
this is a modeled
exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 131
High
Included - worst
case
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A. 15 Wood Preservatives
Table Apx A-15 shows inhalation monitoring data that are available in published literature for use of
NMP-based wood preservative products. In addition to personal monitoring data, EPA presented the
modeled potential inhalation exposures during generic roller/brush application of formulations
containing NMP found in the RIVM Annex XV Proposal for a Restriction - NMP report.
The data presented in Row 1 are applicable to the use of wood preservatives on wooden furniture, not on
utility poles as is assessed in this scenario. Additionally, this sample represents indoor air concentration
of NMP, not personal worker inhalation exposures during the use of wood preservatives on outdoor
utility poles. Thus, this data point is excluded from the risk assessment.
The data presented in Rows 2 through 5 are from a compilation of monitoring data by the German
Institute for Occupational Safety and Health (IFA). These data are listed as "processing and treatment of
wood," with specific work group areas listed as "processing, sanding, removal" ( 310). It is
uncertain if the exposure monitoring data are 8-hour TWA values, but IFA indicates that they are
representative of shift measurements. However, the listed work group areas indicate worker activities
that are not expected to occur during the application of wood preservatives onto utility poles, thus are
not likely to be representative of potential worker inhalation exposures during this scenario.
Due to lack of additional data, EPA used the modeled exposure concentration in Row 6 as the typical
exposure concentration to which workers may be exposed during the use of wood preservatives.
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Table Apx A-15. Summary of Worker Inhalation Exposure Concentrations During Use of Wood Preservatives
Row
Occupational
Exposure
Scenario
Type of Sample
Worker Activity or
Sampling Location
NMP Airborne
Concentration
(mg/m3)
Number of
Samples
Type of
Measurement
Sample Time
Source
Data Identifier
from Data
Extraction and
Evaluation
Overall
Confidence Rating
from Data
Extraction and
Evaluation
Rationale for Inclusion /
Exclusion
1
Unknown
Area
Area with furniture that had
been coated in a wood
preservative mixture
0.142
Unknown
Unknown
Unknown
(NIH,
2017)
3860493 - 102
Low
Excluded - This sample is not
representative of exposures
during this scenario
2
Processing and
treatment of
wood
Area
Listed as "processing,
sanding, removal." Specific
activities and sample areas
are unknown.
50 th percentile:
below analytical
quantification limit of
0.42
90th percentile: 49.8
95th percentile: 149.8
24
Unknown
Unknown - Per source, the sampling
time greater than or equal to 1 hour
and exposure time is greater than or
equal to 6 hours, such that this is
comparable to a shift measurement
(IF A,
2010)
4271620 - 130
Medium
Excluded - the listed
activities are not expected to
be performed during the
application of wood
preservatives onto utility
poles.
3
Processing and
treatment of
wood
Personal
Listed as "processing,
sanding." Specific activities
and sample areas are
unknown.
50th percentile: 0.5
90th percentile: 8.4
95th percentile: 13.9
13
Unknown
Unknown - Per source, the sampling
time greater than or equal to 1 hour
and exposure time is greater than or
equal to 6 hours, such that this is
comparable to a shift measurement
(IF A,
2010)
4271620 - 137
Medium
Excluded - the listed
activities are not expected to
be performed during the
application of wood
preservatives onto utility
poles.
4
Processing and
treatment of
wood
Unknown
Listed as "processing,
sanding, removal." Specific
activities and sample areas
are unknown. Samples taken
in the presence of LEV.
50 th percentile:
below analytical
quantification limit of
0.42
90th percentile: 5.72
95th percentile: 7.8
12
Unknown
Unknown - Per source, the sampling
time greater than or equal to 1 hour
and exposure time is greater than or
equal to 6 hours, such that this is
comparable to a shift measurement
(IF A,
2010)
4271620 - 141
Medium
Excluded - the listed
activities are not expected to
be performed during the
application of wood
preservatives onto utility
poles.
5
Processing and
treatment of
wood
Unknown
Unknown application type.
Unknown area of sampling.
Samples were taken in the
absence of LEV.
50 th percentile:
below analytical
quantification limit of
0.42
90th percentile: 1
95th percentile: 1
14
Unknown
Unknown - Per source, the sampling
time greater than or equal to 1 hour
and exposure time is greater than or
equal to 6 hours, such that this is
comparable to a shift measurement
(IF A,
2010)
4271620 - 148
Medium
Excluded - the listed
activities are not expected to
be performed during the
application of wood
preservatives onto utility
poles.
6
Brush / Roller
Application
Modeled using EasyTRA model
Roll/brush application of
NMP-containing solution
4.13
Not applicable
- this is a
modeled
exposure
8-hour TWA
8 hours
(RIVM.
2013)
3809440 - 115
High
Included as PBPK input
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A. 16 Recycling and Disposal
EPA did not find inhalation monitoring data related to the handling of wastes containing NMP.
Bulk Shipments of Liquid Hazardous Waste
EPA assumes NMP wastes that are generated, transported, and treated or disposed as hazardous waste
are done so as bulk liquid shipments. For example, a facility that uses NMP as a processing aid may
generate and store the waste processing aid as relatively pure NMP and have it shipped to hazardous
waste TSDFs for ultimate treatment, disposal, or recycling. The same monitoring data and modeled data
presented in Appendix A. 1 for the manufacturing of NMP are also applicable to handling of wastes
containing NMP, as these data apply to the transfers (i.e., loading and unloading) of NMP, which occurs
at both manufacturing and waste handling sites. These exposure concentrations assume the handling of
pure (100 percent) NMP.
Due to the limitations of the available monitoring data and RIVM modeled data discussed in Appendix
A. 1, EPA modeled exposures for the unloading of NMP from bulk containers (i.e., tank trucks and rail
cars) and drums. Note that EPA used the same methodology in this section as that described in
Appendix A.l. For bulk containers, the exposure duration is the time required to unload one container,
which is half an hour for tank trucks and one hour for rail cars. For the unloading of drums containing
NMP, EPA used the EPA/OAQPS AP-42 Loading Model and EPA/OPPT Mass Balance Model to
determine exposure duration. Note that, to determine an exposure duration, EPA first determined
throughput of NMP at disposal sites. EPA determined the total production volume for this scenario from
2016 TRI results. Table Apx A-16 lists the off-site waste transfers reported in the 2016 TRI. EPA uses
the total value reported in this table as the production volume for this assessment, excluding off-site
transfers to wastewater treatment, as these are expected to occur via sanitary sewer pipeline. For the
drum unloading exposure scenario, EPA assumes the waste chemical is typically transported to the non-
wastewater treatment and disposal sites in 55-gallon drums and calculates 74,719 total drums per year.
2016 TRI reports 24 waste treatment and disposal sites, resulting in an average of 3,113 drums per site
per year.
Assuming 250 days of operation per year and the model's assumed unloading rate of 20 drums/hour, the
model determined an exposure duration of 0.6 hr/day for recycling and disposal sites.
Table Apx A-16. 2016 TRI Off-Site Transfers for NMP
OIT-Sik' Transfer
Mass (Ih)
Land Disposal
4,272,199
Wastewater Treatmenta
2,719,984
Incineration
9,571,479
Recycled
18,709,460
Other
1,724,080
Total
34,277,218 b
a - Note that EPA does not expect transfers to off-site
wastewater treatment to occur via shipped containers but
expects these transfers are done via sanitary sewer
pipeline.
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OIT-SiU' Transfer
Mass (Ih)
b - Excluding NMP transferred off-site for wastewater
treatment.
EPA uses the calculated PBPK input parameters for full-shift (8-hour TWA) and short-term (acute)
worker inhalation exposures presented in Rows 13 through 16 of Table Apx A-l in Appendix A.l. See
Appendix A. 1 for additional information on the calculation of these exposure concentrations.
Municipal Solid Wastes
Certain commercial and consumer conditions of use of NMP may generate solid wastes that are sent to
municipal waste combustors or landfills. For example, spent aerosol degreasing cans containing residual
NMP used by mechanics or consumers may be disposed as household hazardous waste, which is
exempted as a hazardous waste under RCRA. While some municipalities may have collections of
household hazardous wastes to prevent the comingling of household hazardous wastes with municipal
waste streams, some users may inappropriately dispose of household hazardous wastes in the municipal
waste stream.
EPA is not able to quantitatively assess worker or ONU exposures to NMP within municipal solid waste
streams. The quantities of NMP are expected to be diluted among the comingled municipal solid waste
stream, and uses of NMP, such as aerosol degreasing, result in waste NMP being contained in a sealed
can. Exposures to NMP in spent pressurized cans are only expected if the can is punctured during waste
handling.
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Appendix B Description of Models used to Estimate Worker and ONU
Exposures
B.l Approaches for Estimating Number of Workers
This appendix summarizes the methods that EPA used to estimate the number of workers who are
potentially exposed to NMP in each of its conditions of use. The method consists of the following steps:
1. Identify the North American Industry Classification System (NAICS) codes for the industry
sectors associated with each scenario.
2. Estimate total employment by industry/occupation combination using the Bureau of Labor
Statistics' Occupational Employment Statistics (OES) data (U.S. BLS. 2016).
3. Refine the OES estimates where they are not sufficiently granular by using the U.S. Census'
(2015) Statistics of U.S. Businesses (SUSB) data on total employment by 6-digit NAICS.
4. Estimate the percentage of employees likely to be using NMP instead of other chemicals (i.e., the
market penetration of NMP in the scenario).
5. Estimate the number of sites and number of potentially exposed employees per site.
6. Estimate the number of potentially exposed employees within the scenario.
Step 1: Identifying Affected NAICS Codes
As a first step, EPA identified NAICS industry codes associated with each scenario. EPA generally
identified NAICS industry codes for a scenario by:
• Querying the U.S. Census Bureau's NAICS Search tool using keywords associated with each scenario to
identify NAICS codes with descriptions that match the scenario.
• Referencing EPA Generic Scenarios (GS's) and Organisation for Economic Co-operation and
Development (OECD) Emission Scenario Documents (ESDs) for a scenario to identify NAICS codes
cited by the GS or ESD.
• Reviewing Chemical Data Reporting (CDR) data for the chemical, identifying the industrial sector codes
reported for downstream industrial uses, and matching those industrial sector codes to NAICS codes
using Table D-2 provided in the CDR reporting instructions.
Each scenario section in the main body of this report identifies the NAICS codes EPA identified for the
respective scenario.
Step 2: Estimating Total Employment by Industry and Occupation
BLS's (2016) OES data provide employment data for workers in specific industries and occupations.
The industries are classified by NAICS codes (identified previously), and occupations are classified by
Standard Occupational Classification (SOC) codes.
Among the relevant NAICS codes (identified previously), EPA reviewed the occupation description and
identified those occupations (SOC codes) where workers are potentially exposed to NMP. Table Apx
B-l shows the SOC codes EPA classified as occupations potentially exposed to NMP. These
occupations are classified into workers (W) and occupational non-users (O). All other SOC codes are
assumed to represent occupations where exposure is unlikely.
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TableApx B-l. SOCs with Worker and ONU Designations for All Conditions of Use Except Dry
SOC
Occupation
Designation
11-9020
Construction Managers
O
17-2000
Engineers
O
17-3000
Drafters, Engineering Technicians, and Mapping Technicians
0
19-2031
Chemists
0
19-4000
Life, Physical, and Social Science Technicians
0
47-1000
Supervisors of Construction and Extraction Workers
0
47-2000
Construction Trades Workers
w
49-1000
Supervisors of Installation, Maintenance, and Repair Workers
0
49-2000
Electrical and Electronic Equipment Mechanics, Installers, and
Repairers
w
49-3000
Vehicle and Mobile Equipment Mechanics, Installers, and Repairers
w
49-9010
Control and Valve Installers and Repairers
w
49-9020
Heating, Air Conditioning, and Refrigeration Mechanics and Installers
w
49-9040
Industrial Machinery Installation, Repair, and Maintenance Workers
w
49-9060
Precision Instrument and Equipment Repairers
w
49-9070
Maintenance and Repair Workers, General
w
49-9090
Miscellaneous Installation, Maintenance, and Repair Workers
w
51-1000
Supervisors of Production Workers
0
51-2000
Assemblers and Fabricators
w
51-4020
Forming Machine Setters, Operators, and Tenders, Metal and Plastic
w
51-6010
Laundry and Dry-Cleaning Workers
w
51-6020
Pressers, Textile, Garment, and Related Materials
w
51-6030
Sewing Machine Operators
0
51-6040
Shoe and Leather Workers
0
51-6050
Tailors, Dressmakers, and Sewers
0
51-6090
Miscellaneous Textile, Apparel, and Furnishings Workers
0
51-8020
Stationary Engineers and Boiler Operators
w
51-8090
Miscellaneous Plant and System Operators
w
51-9000
Other Production Occupations
w
W = worker designation
O = ONU designation
For dry cleaning facilities, due to the unique nature of work expected at these facilities and that different
workers may be expected to share among activities with higher exposure potential (e.g., unloading the
dry-cleaning machine, pressing/finishing a dry-cleaned load), EPA made different SOC code worker and
ONU assignments for this scenario. Table Apx B-2 summarizes the SOC codes with worker and ONU
designations used for dry cleaning facilities.
Table Apx B-2. SOCs with Worker and ONU Designations for Dry Cleaning Facilities
SOC
Occupation
Designation
41-2000
Retail Sales Workers
O
49-9040
Industrial Machinery Installation, Repair, and Maintenance Workers
w
49-9070
Maintenance and Repair Workers, General
w
49-9090
Miscellaneous Installation, Maintenance, and Repair Workers
w
51-6010
Laundry and Dry-Cleaning Workers
w
51-6020
Pressers, Textile, Garment, and Related Materials
w
51-6030
Sewing Machine Operators
0
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SOC
Occupation
Designation
51-6040
Shoe and Leather Workers
O
51-6050
Tailors, Dressmakers, and Sewers
O
51-6090
Miscellaneous Textile, Apparel, and Furnishings Workers
O
W = worker designation
O = ONU designation
After identifying relevant NAICS and SOC codes, EPA used BLS data to determine total employment
by industry and by occupation based on the NAICS and SOC combinations. For example, there are
110,640 employees associated with 4-di git NAICS 8123 {Drycleaning and Laundry Services) and SOC
51-6010 (Laundry and Dry-Cleaning Workers).
Using a combination of NAICS and SOC codes to estimate total employment provides more accurate
estimates for the number of workers than using NAICS codes alone. Using only NAICS codes to
estimate number of workers typically result in an overestimate, because not all workers employed in that
industry sector will be exposed. However, in some cases, BLS only provide employment data at the 4-
digit or 5-digit NAICS level; therefore, further refinement of this approach may be needed (see next
step).
Step 3: Refining Employment Estimates to Account for lack of NAICS Granularity
The third step in EPA's methodology was to further refine the employment estimates by using total
employment data in the U.S. Census Bureau's (2015) SUSB. In some cases, BLS OES's occupation-
specific data are only available at the 4-digit or 5-digit NAICS level, whereas the SUSB data are
available at the 6-digit level (but are not occupation-specific). Identifying specific 6-digit NAICS will
ensure that only industries with potential NMP exposure are included. As an example, OES data are
available for the 4-digit NAICS 8123 Drycleaning and Laundry Services, which includes the following
6-digit NAICS:
• NAICS 812310 Coin-Operated Laundries and Dry cleaners;
• NAICS 812320 Drycleaning and Laundry Services (except Coin-Operated);
• NAICS 812331 Linen Supply; and
• NAICS 812332 Industrial Launderers.
In this example, only NAICS 812320 is of interest. The Census data allow EPA to calculate employment
in the specific 6-digit NAICS of interest as a percentage of employment in the BLS 4-digit NAICS.
The 6-digit NAICS 812320 comprises 46 percent of total employment under the 4-digit NAICS 8123.
This percentage can be multiplied by the occupation-specific employment estimates given in the BLS
OES data to further refine our estimates of the number of employees with potential exposure.
Table_Apx B-3 illustrates this granularity adjustment for NAICS 812320.
Table Apx B-3. Estimated Number of Potentially Exposed Workers and ONUs under NAICS
812320
Employment
by SOC at 4-
digit NAICS
level
Estimated
NAICS
SOC
CODE
SOC Description
Occupation
Designation
% of Total
Employment
Employment
by SOC at 6-
digit NAICS
level
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8123
41-2000
Retail Sales Workers
O
44,500
46.0%
20,459
8123
49-9040
Industrial Machinery
Installation, Repair, and
Maintenance Workers
w
1,790
46.0%
823
8123
49-9070
Maintenance and Repair
Workers, General
w
3,260
46.0%
1,499
8123
49-9090
Miscellaneous Installation,
Maintenance, and Repair
Workers
w
1,080
46.0%
497
8123
51-6010
Laundry and Dry-Cleaning
Workers
w
110,640
46.0%
50,867
8123
51-6020
Pressers, Textile, Garment,
and Related Materials
w
40,250
46.0%
18,505
8123
51-6030
Sewing Machine Operators
0
1,660
46.0%
763
8123
51-6040
Shoe and Leather Workers
0
Not Reported for this NAICS Code
8123
51-6050
Tailors, Dressmakers, and
Sewers
0
2,890
46.0%
1,329
8123
51-6090
Miscellaneous Textile,
Apparel, and Furnishings
Workers
0
0
46.0%
0
Total Potentially Exposed Employees
206,070
94,740
Total Workers
72,190
Total Occupational Non-Users
22,551
Note: numbers may not sum exactly due to rounding.
W = worker
O = occupational non-user
Source: (U.S. BLS. 20.1.6: U.S. Census Bureau. 2015")
Step 4: Estimating the Percentage of Workers Using NMP Instead of Other Chemicals
In the final step, EPA accounted for the market share by applying a factor to the number of workers
determined in Step 3. This accounts for the fact that NMP may be only one of multiple chemicals used
for the applications of interest. EPA did not identify market penetration data for any conditions of use.
In the absence of market penetration data for a given scenario, EPA assumed NMP may be used at up to
all sites and by up to all workers calculated in this method as a bounding estimate. This assumes a
market penetration of 100%. Market penetration is discussed for each scenario in the main body of this
report.
Step 5: Estimating the Number of Workers per Site
EPA calculated the number of workers and occupational non-users in each industry/occupation
combination using the formula below (granularity adjustment is only applicable where SOC data are not
available at the 6-digitNAICS level):
Number of Workers or ONUs in NAICS/SOC (Step 2) x Granularity Adjustment Percentage (Step 3) =
Number of Workers or ONUs in the Industry/Occupation Combination
EPA then estimated the total number of establishments by obtaining the number of establishments
reported in the U.S. Census Bureau's SUSB (U.S. Census Bureau. 2015) data at the 6-digit NAICS
level.
EPA then summed the number of workers and occupational non-users over all occupations within a
NAICS code and divided these sums by the number of establishments in the NAICS code to calculate
the average number of workers and occupational non-users per site.
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Step 6: Estimating the Number of Workers and Sites for an Occupational Exposure Scenario
EPA estimated the number of workers and occupational non-users potentially exposed to NMP and the
number of sites that use NMP in a given scenario through the following steps:
6.A. Obtaining the total number of establishments by:
i. Obtaining the number of establishments from SUSB (U.S. Census Bureau. 20.1.5') at the 6-digit
NAICS level (Step 5) for each NAICS code in the scenario and summing these values; or
ii. Obtaining the number of establishments from the Toxics Release Inventory (TRI), Discharge
Monitoring Report (DMR) data, National Emissions Inventory (NEI), or literature for the
scenario.
6.B. Estimating the number of establishments that use NMP by taking the total number of establishments
from Step 6 A and multiplying it by the market penetration factor from Step 4.
6.C. Estimating the number of workers and occupational non-users potentially exposed to NMP by taking
the number of establishments calculated in Step 6.B and multiplying it by the average number of
workers and occupational non-users per site from Step 5.
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B.2 Tank Truck and Railcar Loading and Unloading Release and
Inhalation Exposure Model Approach and Parameters
This appendix presents the modeling approach and model equations used in the Tank Truck and Railcar
Loading and Unloading Release and Inhalation Exposure Model. The model was developed through
review of relevant literature and consideration of existing EPA exposure models. The model approach is
a generic inhalation exposure assessment at industrial facilities that is applicable for any volatile
chemical with the following conditions of use:
• Manufacture (loading of chemicals into containers);
• Processing as a reactant/intermediate (unloading of chemicals);
• Processing into formulation, mixture, or reaction products;
• Repackaging; and
• Other similar conditions of use at industrial facilities (e.g., industrial processing aid).
As an example, NMP at a manufacturing facility is expected to be packaged and loaded into a container
before distributing to another industrial processing or use site (e.g., formulation sites and sites using
NMP as a processing aid). At the industrial processing or use site, NMP is then unloaded from the
container into a process vessel before being incorporated into a mixture or otherwise processed/used.
For the model, EPA assumes NMP is unloaded into tank trucks and railcars and transported and
distributed in bulk. EPA also assumes the chemical is handled as a pure substance (100 percent
concentration).
Because NMP is volatile (vapor pressure above 0.01 torr at room temperature), fugitive emissions may
occur when NMP is loaded into or unloaded from a tank truck or railcar. Sources of these emissions
include:
• Displacement of saturated air containing NMP as the container/truck is filled with liquid;
• Emissions of saturated air containing NMP that remains in the loading arm, transfer hose, and
related equipment; and
• Emissions from equipment leaks from processing units such as pumps, seals and valves.
These emissions result in subsequent exposure to workers involved in the transfer activity. The
following subsections address these emission sources.
B.2.1 Displacement of Saturated Air Inside Tank Trucks and Railcars
For screening-level assessments, EPA typically uses the EPA/OAQPS AP-42 Loading Model to
conservatively assess exposure during container unloading activities (U.S. EPA. 2013a). The model
estimates release to air from the displacement of air containing chemical vapor as a container/vessel is
filled with liquid ( :.013a). The model assumes the unloading activity displaces an air volume
equal to the size of the container, and that displaced air is either 50 percent or 100 percent saturated with
chemical vapor (U.S. EPA. 2013a).
Industrial facilities often install and operate a vapor capture system and control device (or vapor
balancing system) for loading/unloading operations. As such, vapor losses from displacement of air is
likely mitigated by the use of such systems. Actual fugitive emissions are likely limited to any saturated
vapor that remain in the hose, loading arm, or related equipment after being disconnected from the truck
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or railcar. This emission source is addressed in the next subsection.
B.2.2 Emissions of Saturated Air that Remain in Transfer Hoses/Loading Arm
After loading is complete, transfer hoses and/or loading arms are disconnected from tank trucks and
railcars. Saturated air containing the chemical of interest that remains in transfer equipment may be
released to air, presenting a source of fugitive emissions. The quantity of NMP released will depend on
concentration in the vapor and the volume of vapor in the loading arm/hose/piping.
TableApx B-4 presents the dimensions for several types of loading systems according to an OPW
Engineered Systems catalog (Systems. 2014). OPW Engineered Systems (2014) specializes in the
engineering, designing, and manufacturing of systems for loading and unloading a wide range of
materials including petroleum products, liquefied gases, asphalt, solvents, and hazardous and corrosive
chemicals. These systems include loading systems, swivel joints, instrumentation, quick and dry-
disconnect systems, and safety breakaways. Based on the design dimensions, the table presents the
calculated total volume of loading arm/system and assumes the volume of vapor containing NMP equals
the volume of the loading arm/system.
Chemical-specific transport container information was not available; therefore, EPA assumed a default
approach with the "central tendency" as tank truck loading/unloading and the "high-end" as railcar
loading/unloading. Central tendency and high-end approaches are based on the expected transfer arm
volume (and therefore, potential exposure concentration). To estimate the high-end transfer arm volume,
EPA calculated the 95th percentile of the OPW Engineered Systems loading arms volumetric data
resulting in a high-end value of 17.7 gallons. For the central tendency tank truck scenario, EPA assumed
a 2-inch diameter, 12-ft long transfer hose. This hose has a volume of 2.0 gallons.
Once the volume is known, the emission rate, Et (g/s), can be calculated as follows:
EquationApx B-l
_fxMWx3,786AxVhxXxVP
T ~ tdtsconnect x T x R x 3,600 x 760
Default values for Equation Apx B-l can be found in Table Apx B-5.
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Table Apx B-4. Example Dimension and Volume of Loading Arm/Transfer System
Length of Loading
Arm/Connection (in)a
Volume, Vh (gal) b
OPW Engineered Systems Transfer Arm
2-inch
3-inch
4-inch
6-inch
2-
inch
3-
inch
4-
inch
6-
inch
Unsupported Boom-Type Bottom Loader
149.875
158.5
165.25
191.75
2.0
4.9
9.0
23.5
"A" Frame Loader M-32-F
153.75
159.75
164.5
NA
2.1
4.9
8.9
NA
"A" Frame Hose Loader AFH-32-F
180.75
192.75
197.5
NA
2.5
5.9
10.7
NA
CWH Series Counterweighted Hose Loader
NA
NA
309
NA
NA
NA
16.8
NA
Spring Balanced Hose Loader SRH-32-F
204.75
216.75
221.5
NA
2.8
6.6
12.0
NA
Spring Balanced Hose Loader LRH-32-F
NA
270
277.625
NA
NA
8.3
15.1
NA
Top Loading Single Arm Fixed Reach
201.75
207.75
212.5
NA
2.7
6.4
11.6
NA
Top Loading Scissor Type Arm
197.875
206.5
213.25
NA
2.7
6.3
11.6
NA
Supported Boom Arm B-32-F
327.375
335
341.5
NA
4.5
10.3
18.6
NA
Unsupported Boom Arm GT-32-F
215.875
224.5
231.25
NA
2.9
6.9
12.6
NA
Slide Sleeve Arm A-32F
279
292.5
305.125
NA
3.8
9.0
16.6
NA
Hose without Transfer Arm
Hose (EPA judgment)
120
--
--
--
1.6
—
—
—
Source: (Systems. 2014)
a - Total length includes length of piping, connections, and fittings.
b - Calculated based on dimension of the transfer hose/connection, Vh = mrL (converted from cubic inch to gallons).
Table Apx B-5. Default Values for Calculating Emission Rate of N-Methylpyrrolidone from
Transfer/Loading Arm
Parameter
Parameter Description
Default Value
Unit
Et
Emission rate of chemical from transfer/loading
system
Calculated from model
equation
g/s
f
Saturation factor3
1
dimensionless
MW
Molecular weight of the chemical
99.1
g/mol
Vh
Volume of transfer hose
See Table Apx B-4
gallons
r
Fill rate3
2 (tank truck)
1 (railcar)
containers/hour
tdisconnect
Time to disconnect hose/couplers (escape of
saturated vapor from disconnected hose or transfer
arm into air)
0.25
hour
X
Vapor pressure correction factor
1
dimensionless
VP
Vapor pressure of the pure chemical
0.345
ton-
T
Temperature
298
IC
R
Universal gas constant
82.05
atm-cm3/gmol-
K
a - Saturation factor and fill rate values are based on established EPA release and inhalation exposure assessment
methodologies (U.S. EPA. 2013a).
B.2.3 Emission from Leaks
During loading/unloading activities, emissions may also occur from equipment leaks from valves,
pumps, and seals. Per EPA's Chapter 5: Petroleum Industry of AP-42 (U.S. EPA. 2015a) and EPA's
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Protocol for Equipment Leak Emission Estimates (U.S. EPA. 1995). the following equation can be used
to estimate emission rate El, calculated as the sum of average emissions from each process unit:
EquationApx B-2
Z 1,000
(FaxWFT0CxN)Xj^
Parameters for calculating equipment leaks using Equation Apx B-2 can be found in TableApx B-6.
TableApx B-6. Parameters for Calculating Emission Rate of N-Methylpyrrolidone from
Equipment Leaks
Parameter
Parameter Description
Default Value
Unit
El
Emission rate of chemical from equipment leaks
Calculated from
model equation
g/s
Fa
Applicable average emission factor for the
equipment type
See Table Apx B-7
kg/hour-source
WFtoc
Average weight fraction of chemical in the stream
1
dimensionless
N
Number of pieces of equipment of the applicable
equipment type in the stream
See Table Apx B-7
Source
To estimate emission leaks using this modeling approach, EPA modeled a central tendency loading rack
scenario using tank truck loading/unloading and a high-end loading rack scenario using railcar
loading/unloading as discussed in Appendix A.l. EPA used engineering judgment to estimate the type
and number of equipment associated with the loading rack in the immediate vicinity of the loading
operation. EPA assumes at least one worker will be near the loading rack during the entire duration of
the loading operation.
Table Apx B-7 presents the average emission factor for each equipment type, based on the synthetic
organic chemical manufacturing industry (SOCMI) emission factors as provided by EPA's 1995
Protocol (U.S. EPA. 1995). and the likely number of pieces of each equipment used for each chemical
loading/unloading activity, based on EPA's judgment. Note these emission factors are for emission rates
of total organic compound emission and are assumed to be applicable to NMP. In addition, these factors
are most valid for estimating emissions from a population of equipment and are not intended to be used
to estimate emissions for an individual piece of equipment over a short period of time.
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Table Apx B-7. Default Values for Fa and N
SOCMI Emission
Number of
Number of
Equipment Type
Service
Factor, Fa (kg/hour-
source) a
Equipment, N
(central tendency)
Equipment, N
(high-end)
Valves
Gas
Light liquid
Heavy liquid
0.00597
0.00403
0.00023
3 (gas)
5 (heavy liquid)
3 (gas)
10 (heavy liquid)
Pump sealsb
Light liquid
Heavy liquid
0.0199
0.00862
--
--
Compressor seals
Gas
0.228
--
--
Pressure relief valves
Gas
0.104
1
1
Connectors
All
0.00183
2
3
Open-ended lines
All
0.0017
--
--
Sampling connections
All
0.015
2
3
Source: (U.S. EPA. 1995)
a - SOCMI average emission factors for total organic compounds from EPA's 1995 Protocol (U.S. EPA. 1995).
"Light liquid" is defined as "material in a liquid state in which the sum of the concentration of individual
constituents with a vapor pressure over 0.3 kilopascals (kPa) at 20 °C is greater than or equal to 20 weight
percent". "Heavy liquid" is defined as "not in gas/vapor service or light liquid service." Since NMP has a vapor
pressure of 0.345 mmHg (0.046 kPa) at 25 °C, EPA modeled NMP liquid as a light liquid,
b - The light liquid pump seal factor can be used to estimate the leak rate from agitator seals.
EPA assumed the following equipment are used in loading racks for the loading/unloading of tank
trucks and railcars. Figure Apx B-l illustrates an example tank truck and unloading rack equipment.
• Tank Truck Loading/Unloading:
o Liquid Service:
¦ Four valves (modeled as valves in heavy liquid service)
¦ One safety relief valve (modeled as valve in heavy liquid service)
¦ One bleed valve or sampling connection
¦ One hose connector
o Vapor Service:
¦ Three valves (modeled as valves in gas service)
¦ One pressure relief valve
¦ One bleed valve (modeled as a sampling connection)
¦ One hose connector
• Railcar Loading/Unloading
o Liquid Service: EPA assumed, for the high-end scenario, two parallel liquid service lines,
each using the same equipment as assumed for tank trucks. Therefore, a total of:
¦ Eight valves (modeled as valves in heavy liquid service)
¦ Two safety relief valves (modeled as valve in heavy liquid service)
¦ Two bleed valves or sampling connections
¦ Two transfer arm connectors
o Vapor Service: EPA assumed a single line in vapor service with the same equipment as
assumed for tank trucks.
¦ Three valves (modeled as valves in gas service)
¦ One pressure relief valve
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One bleed valve (modeled as a sampling connection)
One transfer arm connector
Vaporservice line
_ Liquidservice line
FigureApx B-l. Illustration of Transfer Lines Used During Tank Truck Unloading and
Associated Equipment Assumed by EPA
B.2.3.1 Exposure Estimates
The vapor generation rate, G, or the total emission rate over time, can be calculated by aggregating
emissions from all sources:
• During the transfer period, emissions are only due to leaks, with emission rate G = EL.
• After transfer, during the disconnection of the hose(s), emissions are due to both leaks and
escape of saturated vapor from the hose/transfer arm with emission rate G = ET + EL.
The vapor generation rate can then be used with the EPA OPPTMass Balance Inhalation Model to
estimate worker exposure during loading/unloading activities (U.S. EPA 2013a). The EPA OPPT Mass
Balance Inhalation Model estimates the exposure concentration using EquationApx B-3 and the default
parameters found in TableApx B-8 (U.S. EPA 2013a). TableApx B-9 presents exposure estimates for
NMP using this approach. These estimates assume one unloading/loading event per day and NMP is
loaded/unloaded at 100% concentration. The loading operation occurs in an outdoor area with minimal
structure, with wind speeds of 9 mph (central tendency) or 5 mph (high-end).
Equation Apx B-3
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TableApx B-8. Parameters for Calculating Exposure Concentration Using the EPA/OPPT Mass
Balance Model
Parameter
Parameter Description
Default Value
Unit
cm
Mass concentration of chemical in air
Calculated from model equation
mg/m3
Cv
Volumetric concentration of chemical
in air
Calculated as the lesser of:
170,000XTX(j 1,000,000XXXW
or
MWXQXk 760
ppm
T
Temperature of air
298
K
G
Vapor generation rate
El during transfer period
Et+El after transfer/during
disconnection of hose/transfer arm
g/s
MW
Molecular weight of the chemical
99.1
g/mol
Q
Outdoor ventilation rate
237,600 (central tendency)
26,400 x (60 x ) (high-end)
V 5280/
ft3/min
vz
Air speed
440
ft/min
k
Mixing factor
0.5
dimensionless
X
Vapor pressure correction factor
1
dimensionless
VP
Vapor pressure of the pure chemical
0.345
torr
Vm
Molar volume
24.45 @ 25°C, 1 atm
L/mol
EPA also calculated acute and 8-hour TWA exposures as shown in EquationApx B-4 and
EquationApx B-5, respectively. The acute TWA exposure is the weighted average exposure during the
entire exposure duration per shift, accounting for the number of loading/unloading events per shift. The
8-hour TWA exposure is the weighted average exposure during an entire 8-hour shift, assuming zero
exposures during the remainder of the shift. EPA assumed one container is loaded/unloaded per shift:
one tank truck per shift for the central tendency scenario and one railcar per shift for the high-end
scenario.
Equation Apx B-4
^m(leak only) ^ 0^-event ~ ^disconnect) (j^m(leak and hose) ^ ^ disconnect)^ ^ ^cont
Acute TWA =
h-shift
Equation Apx B-5
^Cm(leak only) ^ (.h-event ~ tdisconnect) (pm(leak and hose) ^ ^disconnect)) ^ ^cont
8 - hr TWA =
Where:
Cm(ieak only) = Airborne concentration (mass-based) due to leaks during unloading while
hose connected (mg/m3)
Cm(ieak and hose) = Airborne concentration (mass-based) due to leaks and displaced air during
hose disconnection (mg/m3)
hevent = Exposure duration of each loading/unloading event (hour/event);
calculated as the inverse of the fill rate, r : 0.5 hour/event for tank trucks
and 1 hour/event for railcars
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hshift = Exposure duration during the shift (hour/shift); calculated as h event X Ncont'.
0.5 hour/shift for tank trucks and 1 hour/shift for railcars
tdisconnect = Time duration to disconnect hoses/couplers (during which saturated vapor
escapes from hose into air) (hour/event)
Ncont = Number of containers loaded/unloaded per shift (event/shift); assumed one
tank truck per shift for central tendency scenario and one railcar per shift
for high-end scenario
TableApx B-9. Calculated Emission Rates and Resulting Exposures of N-Methylpyrrolidone
from the Tank Truck and Railcar Loading and Unloading Release and Inhalation Exposure
Model
Scenario
El
(g/s)
Et
(g/s)
El +
Et
(g/s)
r
v in
(leaks
only)
(mg/m3)
r
v in
(leaks and hose
vapor)
(mg/m3)
Acute
TWA
(mg/m3)a
8-hour
TWA
(mg/m3)
Central Tendency
0.044
1.52E-05
0.044
0.76
0.76
0.76
0.047
High-End
0.049
1.37E-04
0.049
1.52
1.53
1.52
0.19
a - Acute TWA exposure is a 0.5-hour TWA exposure for the central tendency scenario and a 1-hour TWA exposure for the
high-end scenario.
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B.3 Drum Loading and Unloading Release and Inhalation Exposure
Model Approach and Parameters
This appendix presents the approach for central tendency and high-end inhalation exposure estimation
for the loading and unloading of pure (100%) NMP from 55-gallon drums. This approach applies a
stochastic modeling approach to the EPA/OAQPS AP-42 Loading Model, which estimates air releases
during container loading and unloading, and the EPA /OPPTMass Balance Model, which estimates
inhalation exposures resulting from air releases (U.S. EPA. 2013a).
This approach is intended to assess air releases and associated inhalation exposures associated with
indoor container loading scenarios at industrial and commercial facilities. Inhalation exposure to
chemical vapors is a function of the chemical's physical properties, ventilation rate of the container
loading area, type of loading method, and other model parameters. While physical properties are fixed
for a chemical, some model parameters, such as ventilation rate (Q), mixing factor (k), and vapor
saturation factor (f), are expected to vary from one facility to another. This approach addresses
variability for these parameters using a Monte Carlo simulation.
An individual model input parameter could either have a discrete value or a distribution of values. EPA
assigned statistical distributions based on available literature data or engineering judgment to address the
variability in ventilation rate (Q), mixing factor (k), vapor saturation factor (f), and exposed working
years per lifetime (WY). A Monte Carlo simulation (a type of stochastic simulation) was conducted to
capture variability in the model input parameters. The simulation was conducted using the Latin
hypercube sampling method in @Risk Industrial Edition, Version 7.0.0 (Palisade, Ithaca, New York).
The Latin hypercube sampling method is a statistical method for generating a sample of possible values
from a multi-dimensional distribution. Latin hypercube sampling is a stratified method, meaning it
guarantees that its generated samples are representative of the probability density function (variability)
defined in the model. EPA performed 100,000 iterations of the model to capture the range of possible
input values, including values with low probability of occurrence.
From the distribution resulting from the Monte Carlo simulation, EPA selected the 95th and 50th
percentile values to represent a high-end exposure and central tendency exposure level respectively. The
statistics were calculated directly in @Risk. The following subsections detail the model design equations
and parameters used for Inhalation exposure estimates.
B.4 Model Air Release and Inhalation Exposure Equations
The average vapor generation rate needed to estimate inhalation exposure concentration with
the EPA/OPPTMass Balance Model is calculated from the following EPA/OAQPS AP-42 Loading
Model equation for vapor generation rate.
EquationApx B-6
G =
f x MW x (3,785.4 xVc)xrxXxj^
3,600 XT x R
Where:
G
F
Average vapor generation rate [g/s]
Saturation factor [Dimensionless]
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MW = Molecular weight of chemical [g/mol]
Vc = Container volume [gallon]
r = Container loading/unloading rate [number of containers/hr]
X = Vapor pressure correction factor [ Dimensionless], assumed equal to weight
fraction of component
VP = Vapor pressure (at temperature, T) [mmHg]
T = Temperature [K]
R = Universal gas constant [atm-cm3/mol-K]
The EPA/OPPTMass Balance Model uses EquationApx B-7 to calculate the volumetric concentration
of the chemical in air, using the vapor generation rate calculated above.
Equation Apx B-7
170,000 xTxG
Cy ~ MW xQxk
Where:
Cv
= Volumetric concentration of chemical vapor in air [ppm]
T
= Temperature [K]
G
= Average vapor generation rate [g/s]
MW
= Molecular weight of chemical [g/mol]
Q
= Ventilation rate [ft3/min]
K
= Mixing factor [Dimensionless]
The EPA/OPPT Mass Balance Model then uses EquationApx B-8 to estimate mass concentration of the
chemical vapor in air (mg/m3):
Equation Apx B-8
r =
CvxMW
Vrn
Where:
Cm
Cv
MW
Vn
= Mass concentration of chemical vapor in air [mg/m3]
= Volumetric concentration of chemical vapor in air [ppm]
= Molecular Weight of chemical [g/mol]
= Molar volume [L/mol]
The estimated mass concentration in air is the short-term inhalation exposure concentration. This short-
term exposure is subsequently used in Equation Apx B-9 to estimate the 8-hour TWA exposure
concentration.
Equation Apx B-9
C8-hr
Cm X t
unload
8
hr
day
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Where:
C8-hr = contaminant concentration in air (8-hour TWA) [mg/m3]
Cm = Mass concentration of chemical vapor in air [mg/m3]
tunload = total unloading time for all drums per day [hr/day]
B.5 Number of Containers and Short-Term Exposure Duration
Equations
The short-term exposure duration, tunload, is the length of time workers spend unloading NMP from
drums in a given day. To determine the exposure duration, the number of drums loaded or unloaded at a
given site per day is first calculated with EquationApx B-10.
EquationApx B-10
JV,
PVr
drum_site_day
gal/yr
Vc X Nsifes X OD
Where:
Ndrum site day =
PVgal/yr
Y
Nsites
()[)
Number of drums loaded / unloaded per site per day [drum/site-day]
Production volume for the scenario in gallons of NMP per year [gal/yr]
Volume of container [gallons/drum]
Number of sites [sites]
Operating days [day/yr]
To calculate the production volume in gallons of NMP per year for Equation Apx B-10, the production
volume in pounds per year (included in Table Apx B-10) is converted with Equation Apx B-l 1.
Equation Apx B-ll
PVlb/yr x 453.6
PVgal/yr = TZT-j
p X 3,785 w
Where:
PVgai/yr = Production volume for the scenario in gallons of NMP per year [gal/yr]
PVib/yr = Production volume for the scenario in pounds of NMP per year [lb/yr]
p = density of NMP [g/cm3]
Finally, EPA determined the short-term exposure duration using the number of drums calculated in
Equati onApx B-10.
Equation Apx B-12
^ _ Ndrum_site_day
tunload ~
r
Where:
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tunload = Total unloading time for all drums per day [hr/site-day]
Ndrum site day = Number of drums loaded / unloaded per site per day [drum/site-day]
r = Drum fill rate [drums/hr]
B.6 Model Input Parameters
Table_ApxB-10 summarizes the model parameters and their values for the Monte Carlo simulation. High-
end and central tendency exposure are estimated by selecting the 50th and 95th percentile values from the
output distribution.
TableApx B-10. Summary of Parameter Values and Distributions Used in the Inhalation
Exposure Model
Input Parameter
Symbol
Unit
Constant
Model
Parameter
Values
Variable Model Parameter
Values
Rational / Basis
Value
Lower
Bound
Upper
Bound
Mode
Distribution
Type
Molecular Weight
MW
ft/11101
99.1
—
—
—
Physical property
Vapor Pressure at
298 K
VP
mmHg
0.345
—
—
—
—
Physical property
Molar Volume at
298 K
vm
L/mol
24.46
—
—
—
—
Physical constant
Gas Constant
R
atm-cm3/mol-
K
82.05
—
—
—
—
Temperature
T
K
298
—
—
—
—
Process parameter
Vapor Pressure
Correction Factor
X
Dimensionless
1
—
—
—
—
Process parameter
Mole Fraction of
Chemical
Xi
Dimensionless
1
—
—
—
—
Process parameter, refer to
Appendix A for additional
information
Production Volume
PVlb/yr
lb/yr
Manufacture
and
Rerackasins:
161,000,000
Chemical
Processins and
Formulation:
80,500,000
Recvclins and
Disposal:
34,227,218
—
—
—
—
Process parameter, refer to
Appendix A for additional
information
Number of sites
Nsites
sites
Manufacture
and
Rerackasins:
33
Chemical
Processins and
Formulation: 94
—
—
—
—
Process parameter, refer to
Appendix A for additional
information
Recvclins and
Disposal:
24
Operating Days
OD
day/yr
250
—
—
—
—
Process parameter, based on
schedule of five days per
week and 50 weeks per year
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Input Parameter
Symbol
Unit
Constant
Model
Parameter
Values
Variable Model Parameter
Values
Rational / Basis
Value
Lower
Bound
Upper
Bound
Mode
Distribution
Type
Container Volume
Vo
Gallons/drum
55
—
—
—
Value is determined by the
selected container type for
given exposure scenario
(U.S. EPA. 2013a)
Container
Loading/Unloading
Rate
r
Containers
/ lir
20
—
—
—
—
Value is determined by the
selected container tvoe (U.S.
EPA. 2013a)
Ventilation Rate
0
ft'/in in
—
500
10,000
3,000
Triangular
U.S. EPA (2013a) indicates:
Mixing Factor
k
Dimensionless
—
0.1
1
0.5
Triangular
1. General ventilation rates
in industry ranges from a
low of 500 ftVmin to over
10,000 ftVmin; a typical
value is 3,000.
2. Mixing Factor ranges
from 0.1 to 1.
3. Saturation factor ranges
from 0.5 for submerged
loading to 1.45 for splash
loading.
Underlying distribution of
these parameters are not
known, EPA assigned
triangular distributions,
since triangular distribution
requires least assumptions
and is completely defined
by range and mode of a
parameter.
Saturation Factor
f
Dimensionless
—
0.5
1.45
0.5
Triangular
—: Not Applicable
B.7 Monte Carlo Simulation Results
The probability density function for the short-term exposure concentration values resulting from the
simulation are depicted in Figure Apx B-2. Specifically, EPA used the 50th and 95th percentile short-
term exposure concentration values to represent central tendency and high-end inhalation exposure
potential.
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Short-Term Concentration
>¦
o
c
<1>
3
O"
<1)
(U
cc
25%
20%
15%
> 10%
5%
0%
50th Percentile Value =
95th Percentile Value =
= 1.65 mg/m3
= 5.85 mg/m3
L
r
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10
Short-Term Concentration (mg/m3)
FigureApx B-2. Graphical Probability Density Function of Monte Carlo Simulation Results
The 50th and 95th percentile short-term exposure concentration values are the same for all conditions of
use. However, the 8-hour TWA exposure concentration values vary based on the production volume and
number of sites for each scenario. The short-term and 8-hour TWA inhalation exposure concentrations
are summarized for each scenario for which this model was used in Table Apx B-l 1.
Table Apx B-ll. Drum Loading and Unloading Inhalation Exposure Simulation Results
Occupational
Exposure Scenario
8-hour TWA Exposure
(mg/m3)
Short-Term Exposure
(mg/m3)
Number of Drums
per Site per Day
(drums/site-day)
Short-Term
Exposure
Duration
(hr/day)
50th
Percentile
95th
Percentile
50th
Percentile
95th
Percentile
Manufacturing
0.427
1.510
1.65
5.85
41.3
2.064
Repackaging
0.427
1.510
1.65
5.85
41.3
2.064
Chemical
Processing,
Excluding
Formulation
0.075
0.265
1.65
5.85
7.3
0.362
Formulation
0.075
0.265
1.65
5.85
7.3
0.362
Recycling and
Disposal
0.125
0.441
1.65
5.85
12.1
0.603
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B.8 Brake Servicing Near-Field/Far-Field Inhalation Exposure Model
Approach and Parameters
This appendix presents the modeling approach and model equations used in the Brake Servicing Near-
Field/Far-Field Inhalation Exposure Model. The model was developed through review of the literature
and consideration of existing EPA exposure models. This model uses a near-field/far-field approach
( 2009), where an aerosol application located inside the near-field generates a mist of droplets,
and indoor air movements lead to the convection of the droplets between the near-field and far-field.
Workers are assumed to be exposed to NMP droplet concentrations in the near-field, while occupational
non-users are exposed at concentrations in the far-field.
The model uses the following parameters to estimate exposure concentrations in the near-field and far-
field:
• Far-field size;
• Near-field size;
• Air exchange rate;
• Indoor air speed;
• Concentration of NMP in the aerosol formulation;
• Amount of degreaser used per brake job;
• Number of degreaser applications per brake job;
• Time duration of brake j ob;
• Operating hours per week; and
• Number of j obs per work shift.
An individual model input parameter could either have a discrete value or a distribution of values. EPA
assigned statistical distributions based on available literature data. A Monte Carlo simulation (a type of
stochastic simulation) was conducted to capture variability in the model input parameters. The
simulation was conducted using the Latin hypercube sampling method in @Risk Industrial Edition,
Version 7.0.0. The Latin hypercube sampling method is a statistical method for generating a sample of
possible values from a multi-dimensional distribution. Latin hypercube sampling is a stratified method,
meaning it guarantees that its generated samples are representative of the probability density function
(variability) defined in the model. EPA performed the model at 100,000 iterations to capture the range of
possible input values (i.e., including values with low probability of occurrence).
Model results from the Monte Carlo simulation are presented as 95th and 50th percentile values. The
statistics were calculated directly in @Risk. The 95th percentile value was selected to represent high-end
exposure level, whereas the 50th percentile value was selected to represent central tendency exposure
level. The following subsections detail the model design equations and parameters for the brake
servicing model.
B.8.1 Model Design Equations
In brake servicing, the vehicle is raised on an automobile lift to a comfortable working height to allow
the worker (mechanic) to remove the wheel and access the brake system. Brake servicing can include
inspections, adjustments, brake pad replacements, and rotor resurfacing. These service types often
involve disassembly, replacement or repair, and reassembly of the brake system. Automotive brake
cleaners are used to remove oil, grease, brake fluid, brake pad dust, or dirt. Mechanics may occasionally
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use brake cleaners, engine degreasers, carburetor cleaners, and general purpose degreasers
interchangeably (CARB. 2000). Automotive brake cleaners can come in aerosol or liquid form (CARB.
2000): this model estimates exposures from aerosol brake cleaners (degreasers).
FigureApx B-3 illustrates the near-field/far-field modeling approach as it was applied by EPA to brake
servicing using an aerosol degreaser. The application of the aerosol degreaser immediately generates a
mist of droplets in the near-field, resulting in worker exposures at a NMP concentration Cnf. The
concentration is directly proportional to the amount of aerosol degreaser applied by the worker, who is
standing in the near-field-zone (i.e., the working zone). The volume of this zone is denoted by Vnf. The
ventilation rate for the near-field zone (Qnf) determines how quickly NMP dissipates into the far-field
(i.e., the facility space surrounding the near-field), resulting in occupational bystander exposures to
NMP at a concentration Cff. Vff denotes the volume of the far-field space into which the NMP
dissipates out of the near-field. The ventilation rate for the surroundings, denoted by Qff, determines
how quickly NMP dissipates out of the surrounding space and into the outside air.
NF C
Non-
volatile Source
Figure Apx B-3. The Near-Field/Far-Field Model as Applied to the Brake Servicing Near-
Field/Far-Field Inhalation Exposure Model
In brake servicing using an aerosol degreaser, aerosol degreaser droplets enter the near-field in non-
steady "bursts," where each burst results in a sudden rise in the near-field concentration. The near-field
and far-field concentrations then decay with time until the next burst causes a new rise in near-field
concentration. Based on site data from automotive maintenance and repair shops obtained by CARB
(CARB. 2000) for brake cleaning activities and as explained in Sections B.8.2.5 and B.8.2.9 below, the
model assumes a worker will perform an average of 11 applications of the degreaser product per brake
job with five minutes between each application and that a worker may perform one to four brake jobs
per day each taking one hour to complete. EPA modeled two scenarios: one where the brake jobs
occurred back-to-back and one where brake jobs occurred one hour apart. In both scenarios, EPA
assumed the worker does not perform a brake job, and does not use the aerosol degreaser, during the
first hour of the day.
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EPA denoted the top of each five-minute period for each hour of the day (e.g., 8:00 am, 8:05 am, 8:10
am, etc.) as tm,n. Here, m has the values of 0, 1, 2, 3, 4, 5, 6, and 7 to indicate the top of each hour of the
day (e.g., 8 am, 9 am, etc.) and n has the values of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11 to indicate the top
of each five-minute period within the hour. No aerosol degreaser is used, and no exposures occur, during
the first hour of the day, to,o to to,n (e.g., 8 am to 9 am). Then, in both scenarios, the worker begins the
first brake job during the second hour, ti,o (e.g., 9 am to 10 am). The worker applies the aerosol
degreaser at the top of the second 5-minute period and each subsequent 5-minute period during the hour-
long brake job (e.g., 9:05 am, 9:10 am,... 9:55 am). In the first scenario, the brake jobs are performed
back-to-back, if performing more than one brake job on the given day. Therefore, the second brake job
begins at the top of the third hour (e.g., 10 am), and the worker applies the aerosol degreaser at the top
of the second 5-minute period and each subsequent 5-minute period (e.g., 10:05 am, 10:10 am,... 10:55
am). In the second scenario, the brake jobs are performed every other hour, if performing more than one
brake job on the given day. Therefore, the second brake job begins at the top of the fourth hour (e.g., 11
am), and the worker applies the aerosol degreaser at the top of the second 5-minute period and each
subsequent 5-minute period (e.g., 11:05 am, 11:10 am,... 11:55 am).
In the first scenario, after the worker performs the last brake job, the workers and occupational non-users
(ONUs) continue to be exposed as the airborne concentrations decay during the final three to six hours
until the end of the day (e.g., 4 pm). In the second scenario, after the worker performs each brake job,
the workers and ONUs continue to be exposed as the airborne concentrations decay during the time in
which no brake jobs are occurring and then again when the next brake job is initiated. In both scenarios,
the workers and ONUs are no longer exposed once they leave work.
Based on data from CARB (CARB. 2000). EPA assumes each brake job requires one 14.4-oz can of
aerosol brake cleaner as described in further detail below. The model determines the application rate of
NMP using the weight fraction of PCE in the aerosol product. EPA uses a uniform distribution of weight
fractions for NMP based on facility data for the aerosol products in use (CARB. 2000).
The model design equations are presented below in EquationApx B-13 through EquationApx B-33.
Near-Field Mass Balance
Equation Apx B-13
Far-Field Mass Balance
Equation Apx B-14
Where:
Vnf
Vff
Qnf
Qff
Cnf
Cff
near-field volume;
far-field volume;
near-field ventilation rate;
far-field ventilation rate;
average near-field concentration;
average far-field concentration; and
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t = elapsed time.
Solving EquationApx B-13 and EquationApx B-14 in terms of the time-varying concentrations in the
near-field and far-field yields Equation Apx B-15 and Equation Apx B-16, which EPA applied to each
of the 12 five-minute increments during each hour of the day. For each five-minute increment, EPA
calculated the initial near-field concentration at the top of the period (tm,n), accounting for both the burst
of NMP from the degreaser application (if the five-minute increment is during a brake job) and the
residual near-field concentration remaining after the previous five-minute increment (tm,n-i; except
during the first hour and tm.o of the first brake job, in which case there would be no residual NMP from a
previous application). The initial far-field concentration is equal to the residual far-field concentration
remaining after the previous five-minute increment. EPA then calculated the decayed concentration in
the near-field and far-field at the end of the five-minute period, just before the degreaser application at
the top of the next period (tm,n+i). EPA then calculated a 5-minute TWA exposure for the near-field and
far-field, representative of the worker's and ONUs' exposures to the airborne concentrations during each
five-minute increment using Equation Apx B-25 and Equation Apx B-26. The k coefficients
(Equation Apx B-17 through Equation Apx B-20) are a function of the initial near-field and far-field
concentrations, and therefore are re-calculated at the top of each five-minute period. In the equations
below, where the subscript "m, n-1" is used, if the value of n-1 is less than zero, the value at "m-1, 11"
is used and where the subscript "m, n+1" is used, if the value of n+1 is greater than 11, the value at
"m+1, 0" is used.
Equation Apx B-15
Equation Apx B-16
Where:
Equation Apx B-17
K
CNF t _li — t eXlt ^2 t
iyir>Lm,n+1 v z>Lm,n J
Cpp t M=(k3t eXlt-kAt e^)
rr>Lm,n+1 V s>lm,n ^>lm,n J
QnF {^FF.O^m.n) ^NF.oiSm.n}) ^^NF^NF.oiSm.n)
tr
mn Vnf&i ~ ^2)
Equation Apx B-18
QnF (CwF,o(tm,n) — ^FF,0 (*771,71)) + ^-l^VF^JVF.O(*771,71)
2,tm,n Vnf(A, — A2)
Equation Apx B-19
(QnF + ^1Vnf)(.QnF (CFF,o(tm,n) ~ ^NF,o{^m,nS) ~ ^ 2 Kv F ^/V F, 0 (*771,71) )
kn
3,tmn Qnf^nf(^i ~ ^2)
Equation Apx B-20
(.QnF + ^2^Nf){QnF (CWF,o(tm,n) — CFF 0(tmn)^ + A^Vj^pCj^p 0(tmn))
4'tm,n Qnf^nf(^i ^2)
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EquationA
Aj_ = 0.5
EquationA
X2 = 0.5
PEER REVIEW DRAFT - DO NOT CITE OR QUOTE
ox B-21
(Qnf^ff + Vnf(Qnf + Qff)\ /Qnf^ff + Vnf(Qnf + Qff)\ _ . /QnfQff\
\ ^NF^FF ) J\ VnF^FF J \VNFVFF)
ox B-22
f QnF^FF + Vnf(QnF + Qff) \ I /Qnf^ff + Vnf(.Qnf + Qff) \ _ . /QnfQff\
\ ^/VF^FF / J\ ^/VF^FF / V ^/VF^FF '
EquationApx B-23
f 0, m = 0
CNF,o{tm,n) — "j {1000—+ CMpftmn-i) , n > 0 for all m where brake job
{VNP v 9 > '
Equation Apx B-24
r 0, m = 0
FF,o\tm,n) — [CFF(tmn_x) , for all n where m > 0
occurs
Equation Apx B-25
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EquationApx B-29
r _ Hr!=o[C/vF,5-min TWA,tmjl x 0-0833 hr\
CNF, 1-hr TWA - Yhr"
Equation Apx B-30
r _ Hn=0 \pFF,5-min TWA,tm,n X 0.0833 hr\
CFF,1-hr TWA ~
EPA calculated rolling 1-hour TWA's throughout the workday and the model reports the maximum
calculated 1-hour TWA.
To calculate the mass transfer to and from the near-field, the free surface area (FSA) is defined to be the
surface area through which mass transfer can occur. The FSA is not equal to the surface area of the
entire near-field. EPA defined the near-field zone to be a hemisphere with its major axis oriented
vertically, against the vehicle, and aligned through the center of the wheel (see Figure Apx 7). The top
half of the circular cross-section rests against, and is blocked by, the vehicle and is not available for
mass transfer. The FSA is calculated as the entire surface area of the hemisphere's curved surface and
half of the hemisphere's circular surface per EquationApx B-31, below:
Equation Apx B-31
FSA = x AtcR^p^ + x TcRftF^j
Where: Rnf is the radius of the near-field
The near-field ventilation rate, Qnf, is calculated in Equation Apx B-32 from the indoor wind speed,
vnf, and FSA, assuming half of the FSA is available for mass transfer into the near-field and half of the
FSA is available for mass transfer out of the near-field:
Equation Apx B-32
1
Qnf — 2 vnfFSA
The far-field volume, Vff, and the air exchange rate, AER, is used to calculate the far-field ventilation
rate, Qff, as given by Equation Apx B-33:
Equation Apx B-33
Qff = Vff^ER
Using the model inputs described in Appendix B.8.2, EPA estimated NMP inhalation exposures for
workers in the near-field and for occupational non-users in the far-field. EPA then conducted the Monte
Carlo simulations using @Risk (Version 7.0.0). The simulations applied 100,000 iterations and the Latin
Hypercube sampling method.
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B.8.2 Model Parameters
Table Apx B-12 summarizes the model parameters and their values for the Brake Servicing Near-
Field/Far-Field Inhalation Exposure Model. Each parameter is discussed in detail in the following
subsections.
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TableApx B-12. Summary of Parameter Values and Distributions Used in the Brake Servicing Near-Field/Far-Field Inhalation
Exposure Model
Input
Parameter
Symbol
Unit
Constant Model
Parameter Values
Variable Model Parameter Values
Comments
Value
Basis
Lower
Bound
Upper
Bound
Mode
Distributio
n Type
Far-field volume
Vff
m3
—
—
206
70,679
3,769
Triangular
Distribution based on data
collected bv CARB (CARD.
2006).
Air exchange
rate
AER
lir1
—
—
1
20
3.5
Triangular
(Demon et al.. 2009) identifies
typical AERs of 1 lir1 and 3 to 20
lir1 for occupational settings
without and with mechanical
ventilation systems, respectively.
(Hellwee et al.. 2009) identifies
average AERs for occupational
settings utilizing mechanical
ventilation systems to be between
3 and 20 lir1. (Golsteiin et al..
2014) indicates a characteristic
AER of 4 lir1. Peer reviewers of
EPA's 2013 TCE draft risk
assessment commented that
values around 2 to 5 lir1 may be
more likelv (U.S. EPA. 2013a). in
agreement with (Golsteiin et al..
2014). A trianeular distribution is
used with the mode equal to the
midpoint of the range provided by
the peer reviewer (3.5 is the
midpoint of the range 2 to 5 lir1).
Near-field indoor
wind speed
Vkf
Mir
1,037
50th
percentile
—
—
—
Lognonnal
Lognonnal distribution fit to
commercial-type workplace data
from Baldwin and Maynard
(1998).
cm/s
8.78
50th
percentile
—
—
—
Lognonnal
Near-field radius
Rnf
m
1.5
—
—
—
—
Constant
Value
Constant.
Starting time for
each application
period
tl
lir
0
—
—
—
—
Constant
Value
Constant.
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Input
Parameter
Symbol
Unit
Constant Model
Parameter Values
Variable Model Parameter Values
Comments
Value
Basis
Lower
Bound
Upper
Bound
Mode
Distributio
n Type
End time for
each application
period
t2
hr
0.0833
—
—
—
—
Constant
Value
Assumes aerosol degreaser is
applied in 5-minute increments
during brake job.
Averaging Time
tavg
hr
8
—
—
—
—
Constant
Value
Constant.
NMP weight
fraction
wtfrac
wt frac
—
—
0.045
0.40
—
Discrete
Discrete distribution of NMP-
based aerosol product
formulations based on products
identified in EPA (U.S. EPA.
2017b).
Degreaser Used
per Brake Job
wd
oz/job
14.4
—
—
—
—
Constant
Value
Based on data from CARB
(CARB. 2000).
Number of
Applications per
Job
Na
Applications/
job
11
—
—
—
—
Constant
Value
Calculated from the average of
the number of applications per
brake and number of brakes per
job.
Amount Used
per Application
Amt
gNMP/
application
—
—
1.7
14.8
—
Calculated
Calculated from wtfrac, Wd, and
Na.
Operating hours
per week
OHpW
hr/week
—
—
40
82.5
—
Lognonnal
Lognonnal distribution fit to the
operating hours per week
observed in CARB (CARB.
2000) site visits.
Number of
Brake Jobs per
Work Shift
Nj
jobs/site-sliift
—
—
2
4
—
—
Calculated from the average
number of brake jobs per site per
year, OHpW, and assuming 52
operating weeks per year and 8
hours per work shift.
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B.8.2.1 Far-Field Volume
The far-field volume is based on information obtained from CARB (2000) from site visits of 137
automotive maintenance and repair shops in California. CARB (2000) indicated that shop volumes at the
visited sites ranged from 200 to 70,679 m3 with an average shop volume of 3,769 m3. Based on this data
EPA assumed a triangular distribution bound from 200 m3 to 70,679 m3 with a mode of 3,769 m3 (the
average of the data from CARB (2000).
CARB measured the physical dimensions of the portion of the facility where brake service work was
performed at the visited facilities. CARB did not consider other areas of the facility, such as customer
waiting areas and adjacent storage rooms, if they were separated by a normally closed door. If the door
was normally open, then CARB did consider those areas as part of the measured portion where brake
servicing emissions could occur (CARB. 2000). CARB's methodology for measuring the physical
dimensions of the visited facilities provides the appropriate physical dimensions needed to represent the
far-field volume in EPA's model. Therefore, CARB's reported facility volume data are appropriate for
EPA's modeling purposes.
B.8.2.2 Air Exchange Rate
The air exchange rate (AER) is based on data from (Golsteiin et ai. 2014; Demou et al. 2009; Hellweg
et al.. 2009). and information received from a peer reviewer during the development of the 2014 TSCA
Work Plan Chemical Risk Assessment Trichloroethylene: Degreasing, Spot Cleaning and Arts & Crafts
Uses (U.S. EPA. 2013a). (Demon et al.. 2009) identifies typical AERs of 1 hr"1 and 3 to 20 hr"1 for
occupational settings without and with mechanical ventilation systems, respectively. Similarly, (Hellweg
et al.. 2009) identifies average AERs for occupational settings using mechanical ventilation systems to
vary from 3 to 20 hr"1. (Golsteiin et al.. 2014) indicates a characteristic AER of 4 hr"1. The risk
assessment peer reviewer comments indicated that values around 2 to 5 hr"1 are likely (U.S. EPA.
2013a). in agreement with Golsteijn, et al. (2014) and the low end reported by (Demon et al.. 2009) and
(Hellweg et al.. 2009). Therefore, EPA used a triangular distribution with the mode equal to 3.5 hr"1, the
midpoint of the range provided by the risk assessment peer reviewer (3.5 is the midpoint of the range 2
to 5 hr"1), with a minimum of 1 hr"1, per (Demou et al.. 2009) and a maximum of 20 hr"1 per (Demou et
al.. 2.009) and (Hellweg et al.. 2.009).
B.8.2.3 Near-Field Indoor Air Speed
Baldwin and Maynard (1998) measured indoor air speeds across a variety of occupational settings in the
United Kingdom. Fifty-five work areas were surveyed across a variety of workplaces.
EPA analyzed the air speed data from Baldwin and Maynard (1998) and categorized the air speed
surveys into settings representative of industrial facilities and representative of commercial facilities.
EPA fit separate distributions for these industrial and commercial settings and used the commercial
distribution for facilities performing aerosol degreasing.
EPA fit a lognormal distribution for both data sets as consistent with the authors observations that the air
speed measurements within a surveyed location were lognormally distributed and the population of the
mean air speeds among all surveys were lognormally distributed. Since lognormal distributions are
bound by zero and positive infinity, EPA truncated the distribution at the largest observed value among
all of the survey mean air speeds from Baldwin and Maynard (1998).
EPA fit the air speed surveys representative of commercial facilities to a lognormal distribution with the
following parameter values: mean of 10.853 cm/s and standard deviation of 7.883 cm/s. In the model,
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the lognormal distribution is truncated at a maximum allowed value of 202.2 cm/s (largest surveyed
mean air speed observed in Baldwin and Maynard (1998) to prevent the model from sampling values
that approach infinity or are otherwise unrealistically large.
Baldwin and Maynard (1998) only presented the mean air speed of each survey. The authors did not
present the individual measurements within each survey. Therefore, these distributions represent a
distribution of mean air speeds and not a distribution of spatially-variable air speeds within a single
workplace setting. However, a mean air speed (averaged over a work area) is the required input for the
model.
B.8.2.4 Near-Field Volume
EPA defined the near-field zone to be a hemisphere with its major axis oriented vertically, against the
vehicle, and aligned through the center of the wheel (see FigureApx 1). The near-field volume is
calculated per EquationApx B-34. EPA defined a near-field radius (Rnf) of 1.5 meters, approximately
4.9 feet, as an estimate of the working height of the wheel, as measured from the floor to the center of
the wheel.
Equation Apx B-34
1 4
V nf = 2 X 3 71
B.8.2.5 Application Time
EPA assumed an average of 11 brake cleaner applications per brake job (see Section B.8.2.9). CARB
observed, from their site visits, that the visited facilities did not perform more than one brake job in any
given hour (CARB. 2.000). Therefore, EPA assumed a brake job takes one hour to perform. Using an
assumed average of 11 brake cleaner applications per brake job and one hour to perform a brake job,
EPA calculates an average brake cleaner application frequency of once every five minutes (0.0833 hr).
EPA models an average brake job of having no brake cleaner application during its first five minutes
and then one brake cleaner application per each subsequent 5-minute period during the one-hour brake
job.
B.8.2.6 Averaging Time
EPA was interested in estimating 8-hr TWAs for use in risk calculations; therefore, a constant averaging
time of eight hours was used.
B.8.2.7 NMP Weight Fraction
EPA reviewed the Use and Market Profile for N-methylpyrrolidone (NMP) report (Abt. 2017) for
aerosol degreasers that contain NMP. EPA ( 2017b) identifies two aerosol cleaners that
overall range in NMP content from 4.5 to 40 weight percent. The identified aerosol cleaners are a gun
bore cleaner and a resin remover. EPA includes these aerosol cleaners in the estimation of NMP content
as EPA uses this brake servicing model as an exposure scenario representative of all commercial-type
aerosol degreaser applications.
EPA used a discrete distribution to model the NMP weight fraction based on the number of occurrences
of each product type. EPA modeled a 50% probability of occurrence for each of the two aerosol cleaner
products. The gun bore cleaner (Break-Free bore cleaning foam) contains 4.5 weight percent NMP and
the resin remover (Slide resin remover) contains 35 to 40 weight percent. EPA used a uniform
distribution to model the NMP weight fraction within the resin remover.
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B.8.2.8 Volume of Degreaser Used per Brake Job
CARB (2000) assumed that brake jobs require 14.4 oz of aerosol product. EPA did not identify other
information to estimate the volume of aerosol product per job; therefore, EPA used a constant volume of
14.4 oz per brake job based on CARB (2000).
B.8.2.9 Number of Applications per Brake Job
Workers typically apply the brake cleaner before, during, and after brake disassembly. Workers may
also apply the brake cleaner after brake reassembly as a final cleaning process (CARB. 2000).
Therefore, EPA assumed a worker applies a brake cleaner three or four times per wheel. Since a brake
job can be performed on either one axle or two axles ( 2000). EPA assumed a brake job may
involve either two or four wheels. Therefore, the number of brake cleaner (aerosol degreaser)
applications per brake job can range from six (3 applications/brake x 2 brakes) to 16 (4
applications/brake x 4 brakes). EPA assumed a constant number of applications per brake job based on
the midpoint of this range of 11 applications per brake job.
B.8.2.10 Amount of NMP Used per Application
EPA calculated the amount of NMP used per application using EquationApx B-35. The calculated
mass of perchloroethylene used per application ranges from 1.7 to 14.8 grams.
Equation Apx B-35
Where:
Amt
Wd
Wtfrac
Na
Amt =
Wd x wtfrac x 28.3495^-
oz
Na
Amount of NMP used per application (g/application);
Weight of degreaser used per brake job (oz/job);
Weight fraction of NMP in aerosol degreaser (unitless); and
Number of degreaser applications per brake job (applications/job).
B.8.2.11 Operating Hours per Week
CARB (2000) collected weekly operating hour data for 54 automotive maintenance and repair facilities.
The surveyed facilities included service stations (fuel retail stations), general automotive shops, car
dealerships, brake repair shops, and vehicle fleet maintenance facilities. The weekly operating hours of
the surveyed facilities ranged from 40 to 122.5 hr/week. EPA fit a lognormal distribution to the surveyed
weekly operating hour data. The resulting lognormal distribution has a mean of 16.943 and standard
deviation of 13.813, which set the shape of the lognormal distribution. EPA shifted the distribution to
the right such that its minimum value is 40 hr/week and set a truncation of 122.5 hr/week (the truncation
is set as 82.5 hr/week relative to the left shift of 40 hr/week).
B.8.2.12 Number of Brake Jobs per Work Shift
CARB (2000) visited 137 automotive maintenance and repair shops and collected data on the number of
brake jobs performed annually at each facility. CARB calculated an average of 936 brake jobs
performed per facility per year. EPA calculated the number of brake jobs per work shift using the
average number of jobs per site per year, the operating hours per week, and assuming 52 weeks of
operation per year and eight hours per work shift using Equation Apx B-36 and rounding to the nearest
integer. The calculated number of brake jobs per work shift ranges from one to four.
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EquationApx B-36
Where:
Nj
OHpW
N,=
936_M£_x8*£!£
site-year shif t
r„wee/cs „.. ...
52 x OHpW
yr
Number of brake jobs per work shift (j ob s/site-shift); and
Operating hours per week (hr/week).
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