P age B -1 

## Technical Support Document for U.S. EPA’s Proposed Rule for Addition of a Subsurface Intrusion Component to the Hazard Ranking System 

# Appendix B: Chemical Factor Analysis

Table B-1: Table B-2: Table B-3: Draft

S ubsurface In trusion H RS F actor Valu es and Benchmark s for Volatile Substances Hazardous Substance Inhalation Unit Risks (IUR s) Ha zar do us Substance Reference Co ncentration s (RfC s)Page B - 2 

## Chemical Factor Analysis As part of the development of the proposed Hazard Ranking System ( HRS ) addition, EPA has adopted a procedure for using Inhalation Unit Risk (IUR) and Reference concentration ( RfC ) values in determining the human toxicity factor and for assigning HRS benchmarks reflecting non - cancer related risk levels for inhalation exposures. Additional information regarding the use of RfCs instead of Reference Doses ( RfDs ) in the proposed HRS add ition is detailed in Section 9.0.b of the proposal ’s technical support document ( TSD )
. Tables B

- 1, B

- 2 and B

- 3 (below) contain the information used to develop the procedure for using the IURs and the RfCs to assign human toxicity factor values. Table B

- 1 provides the human toxicity factor value, air gas migration factor value (vapor migration potential values) , inhalation Reference Dose Screening Concentration benchmark and inhalation cancer risk screening concentration benchmarks for a partial list of com mon volatile substances consistent with the 1990 HRS
. The IURs and RfCs used in developing the new procedures are presented in Tables B

- 2 and B

- 3. An explanation of how the human toxicity factor value is determined and used in calculating the waste charac teristics factor category value can be found in Sections 2.4.1.1 and 5.2.1.2.1 of the proposed HRS additions. Air gas migration numbers are provided for the evaluated substances to aid in assigning the vapor migration potential value, which is used to dete rmine the likelihood of exposure factor category value via potential for exposure, as described in Section 5.2.1.1.2.4 and Table 5

- 17 of the proposed HRS additions.

.Please note, that these are draft HRS factor values and health

- based benchmarks that are provided for testing purposes only and are subject to change. Page B - 3 

## Table B - 1 Draft Subsurface Intrusion HRS Factor Values and Benchmarks for Volatile Substances

Substance Name CAS Number Toxicity Vapor Migration Potential Values Inhalation RfD Screening Conc. (mg/m 3 ) Inhalation Cancer Risk Screening Conc. (mg/m 3 ) Acenaphthene 83

- 32

- 9 10 11

- - Acetone 67

- 64

- 1 1 17 3.2E+1

- Acrolein 107

- 02

- 8 10000 17 2.1E

- 5

- Anthracene 120

- 12

- 7 10 6

- - Benzene 71

- 43

- 2 1000 17 3.1E

- 2 3.1E

- 4 Bromodichloromethane 75

- 27

- 4 100 17

- 6.6E

- 5 Carbon disulfide 75

- 15

- 0 10 17 7.3E

- 1

- Carbon tetrachloride 56

- 23

- 5 1000 17 1.0E

- 1 4.1E

- 4 Chlorobenzene 108

- 90

- 7 100 17 5.2E

- 2

- Chloroform 67

- 66

- 3 100 17 1.0E

- 1 1.1E

- 4 Cumene 98

- 82

- 8 10 17 4.2E

- 1

- Dibenzofuran 132

- 64

- 9 1000 11

- - Dibromo

- 3

- chloropropane, 1,2

- 96

- 12

- 8 10000 11 2.1E

- 4 1.6E

- 7 Dibromoethane, 1,2

- 106

- 93

- 4 10000 17 9.4E

- 3 4.1E

- 6 Dichlorobenzene, 1,4

- 106

- 46

- 7 100 17 8.3E

- 1 2.2E

- 4 Dichloroethane, 1,1

- 75

- 34

- 3 10 17

- 1.5E

- 3 Dichloroethane, 1,2

- 107

- 06

- 2 100 17 7.3E

- 3 9.4E

- 5 Dichloroethylene, 1,1

- 75

- 35

- 4 10 17 2.1E

- 1

- Dichloroethylene, 1,2

- ( mixed isomers ) 540

- 59

- 0 100 17

- -Please note, that these are draft HRS factor values and health

- based benchmarks that are provided for testing purposes only and are subject to change. Page B - 4 

## Table B - 1 (cont.) Draft Subsurface Intrusion HRS Factor Values and Benchmarks for Volatile Substances
Substance Name CAS Number Toxicity Vapor Migration Potential Values Inhalation RfD Screening Conc. (mg/m3) Inhalation Cancer Risk Screening Conc. (mg/m3) Dichloroethylene, 1,2

- cis

- 156

- 59

- 2 1000 17

- - Dichloroethylene, 1,2

- trans
- 156

- 60

- 5 100 17 6.3E

- 2

- Dichloropropane, 1,2

- 78

- 87

- 5 1000 17 4.2E

- 3 2.4E

- 4 Dichloropropene, 1,3

- 542

- 75

- 6 100 17 2.1E

- 2 6.1E

- 4 Ethylbenzene 100

- 41

- 4 10 17 1.0E+0 9.7E

- 4 Fluorene 86

- 73

- 7 100 11

- - Mercury (elemental) 7439

- 97

- 6 1000 17 3.1E

- 4

- Methyl ethyl ketone (2

- butanone) 78

- 93

- 3 1 17 5.2E+0

- Methyl tert

- butyl ether (MBT E ) 1634

- 04

- 4 10 17 3.1E+0 9.4E

- 3 Methylene chloride 75

- 09

- 2 10 17 1.1E+0 5.2E

- 3 Methylnaphthalene, 2

- 91

- 57

- 6 1000 11

- - Naphthalene 91

- 20

- 3 1000 11 3.1E

- 3 7.2E

- 5 Nitrobenzene 98

- 95

- 3 1000 11 9.4E

- 3 6.1E

- 5 Pyrene 129

- 00

- 0 100 6

- - Styrene 100

- 42

- 5 10 17 1.0E+0

- Tetrachloroethane, 1,1,2,2

- 79

- 34

- 5 100 11

- 4.2E

- 5 Tetrachloroethylene 127

- 18

- 4 100 17 2.8E

- 1 4.1E

- 4 Toluene 108

- 88

- 3 10 17 5.2E+0

- Trichlorobenzene, 1,2,4

- 120

- 82

- 1 1000 17 2.1E

- 3

- Trichloroethane, 1,1,1

- 71

- 55

- 6 1 17 5.2E+0

- Trichloroethane, 1,1,2

- 79

- 00

- 5 1000 17 2.1E

- 4 1.5E

- 4 Trichloroethylene 79

- 01

- 6 1000 17 2.1E

- 3 5.9E

- 4 Trichlorofluoromethane 75

- 69

- 4 10 17 7.3E

- 1

- Trichloropropane, 1,2,3

- 96

- 18

- 4 10000 11 3.1E

- 4

- Vinyl acetate 108

- 05

- 4 10 17 2.1E

- 1

- Vinyl chloride 75

- 01

- 4 10000 17 1.0E

- 1 1.6E

- 4 Xylene, m

- 108

- 38

- 3 100 17 1.0E

- 1

- Xylene, o

- 95

- 47

- 6 100 17 1.0E

- 1

- Xylene, p

- 106

- 42

- 3 100 17 1.0E

- 1

- Xylenes 1330

- 20

- 7 100 17 1.0E

- 1

-Page B - 5 

## Table B - 2 Hazardous Substance Inhalation Unit Risk s (IURs) Substance Name Inhalation Unit Risk (IUR) Weight - ofEvidence (WOE) Benzene 2 0.0000078 A Vinyl chloride (2) 0.0000088 A 1,3

- Butadiene 0.00003 A Bis(chloroethyl)ether (BCEE) 0.00033 A Coke oven emissions 0.00062 A Arsenic, inorganic 0.0043 A Chromium(VI) 0.012 A Bis(chloromethyl)ether (BCME) 0.062 A Benzidine 0.067 A Nickel refinery dust 0.00024 A Nickel subsulfide 0.00048 A Trichloroethylene 0.000004 B Chloroform 0.000023 B Hexachloroethane 0.000004 B1 Carbon tetrachloride 0.000006 B1 Nitrobenzene 0.00004 B1 Acrylonitrile 0.000068 B1 Acrylamide 0.0001 B1 Chloroprene 0.0003 B1 1,2

- Dibromoethane (2) 0.0006 B1 Cadmium 0.0018 B1 Beryllium and compounds 0.0024 B1 Formaldehyde 0.000013 B1 Bromoform 0.0000011 B2 Acetaldehyde 0.0000022 B2 2,4,6

- Trichlorophenol 0.0000031 B2 Propylene oxide 0.0000037 B2 Aramite 0.0000071 B2 Azobenzene 0.000031 B2 p,p'

- Dichlorodiphenyltrichloroethane (DDT) 0.000097 B2 Chlordane (Technical) 0.0001 B2 Polychlorinated biphenyls (PCBs) 0.0001 B2 Toxaphene 0.00032 B2 technical Hexachlorocyclohexane (t

- HCH) 0.00051 B2 N

- Nitrosopyrrolidine 0.00061 B2 N

- Nitroso

- di

- n - butylamine 0.0016 B2 alpha

- Hexachlorocyclohexane (alpha

- HCH) 0.0018 B2 Aldrin 0.0049 B2 N

- Nitrosodiethylamine 0.043 B2 Hexachlorodibenzo

- p - dioxin (HxCDD), mixture of 1,2,3,6,7,8

- HxCDD and 1,2,3,7,8,9

- HxCDD 1.3 B2Page B - 6 

## Table B - 2 (cont.) Hazardous Substance Inhalation Unit Risk s (IURs) Substance Name Inhalation Unit Risk (IUR) Weight - ofEvidence (WOE) N

- Nitrosodimethylamine 0.014 B2 1,3

- Dichloropropene 0.000004 B2 Hexachlorobenzene 0.00046 B2 Heptachlor epoxide 0.0026 B2 Dichloromethane 0.00000047 B2 Epichlorohydrin 0.0000012 B2 1,2

- Dichloroethane 0.000026 B2 1,2

- Diphenylhydrazine 0.00022 B2 Heptachlor 0.0013 B2 Dieldrin 0.0046 B2 1,1,1,2

- Tetrachloroethane 0.0000074 C 1,1,2

- Trichloroethane 0.000016 C Hexachlorobutadiene 0.000022 C beta

- Hexachlorocyclohexane (beta

- HCH) 0.00053 CPage B - 7 

## Table B - 3 Hazardous Substance Reference Concentrations (RfCs) Substance Name Reference Concentration (RfC) Acetaldehyde 0.009 Acetonitrile 0.06 Acrolein 0.00002 Acrylamide 0.006 Acrylic acid 1000 Acrylonitrile 0.002 Allyl chloride 0.001 Ammonia 0.1 Aniline 0.001 Antimony trioxide 0.0002 Arsine 0.00005 Benzene 0.03 Beryllium and compounds 0.00002 Bromobenzene 0.06 Bromomethane 0.005 1,3

- Butadiene 0.002 Carbon disulfide 0.7 Carbon tetrachloride 0.1 Cerium Oxide and Cerium Compounds 0.0009 Chlordane (Technical) 0.0007 Chlorine dioxide 0.0002 1

- Chloro

- 1,1

- difluoroethane 50 2

- Chloroacetophenone 0.00003 Chlorodifluoromethane 50 Chloroprene 0.02 Chromium(VI) 0.0001 Chromium(VI) 0.000008 Cumene 0.4 Cyclohexane 6 1,2

- Dibromo

- 3

- chloropropane (DBCP) 0.0002 1,2

- Dibromoethane 0.009 1,4

- Dichlorobenzene 0.8 1,1

- Dichloroethylene (1,1

- DCE) 0.2 1,2

- Dichloropropane 0.004 1,3

- Dichloropropene 0.02 Dichlorvos 0.0005 Diesel engine exhaust 0.005 1,1

- Difluoroethane 40 N,N

- Dimethylformamide 0.03 Epichlorohydrin 0.001 1,2

- Epoxybutane (EBU) 0.02 2

- Ethoxyethanol 0.2Page B - 8 

## Table B - 3 (cont.) Hazardous Substance Reference Concentrations (RfCs) Substance Name Reference Concentration (RfC) Ethyl chloride 10 Ethylbenzene 1 Ethylene glycol monobutyl ether (EGBE) (2

- Butoxyethanol) 1.6 Hexachlorocyclopentadiene (HCCPD) 0.0002 1,6

- Hexamethylene diisocyanate 0.00001 n - Hexane 0.7 2

- Hexanone 0.03 Hydrogen Cyanide and Cyanide Salts 0.0008 Hydrogen chloride 0.02 Hydrogen sulfide 0.002 Manganese 0.00005 Mercury, elemental 0.0003 2

- Methoxyethanol 0.02 Methyl chloride 0.09 Methyl ethyl ketone (MEK) 5 Methyl isobutyl ketone (MIBK) 3 Methyl methacrylate 0.7 Methyl tert

- butyl ether (MTBE) 3 Methylene Diphenyl Diisocyanate (monomeric MDI) and polymeric MDI (PMDI) 0.0006 Naphthalene 0.003 Nitrobenzene 0.009 2

- Nitropropane 0.02 Phosgene 0.0003 Phosphine 0.0003 Phosphoric acid 0.01 Propionaldehyde 0.008 Propylene glycol monomethyl ether (PGME) 2 Propylene oxide 0.03 Styrene 1 1,1,1,2

- Tetrafluoroethane 80 Toluene 5 2,4

- /2,6

- Toluene diisocyanate mixture (TDI) 0.00007 1,1,1

- Trichloroethane 5 1,2,3

- Trichloropropane 0.0003 Triethylamine 0.007 Vinyl acetate 0.2 Vinyl bromide 0.003 Vinyl chloride 0.1 Xylenes 0.1 Trichloroethylene 0.0005