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Title 40Chapter ISubchapter CPart 68Subpart F → §68.130


Title 40: Protection of Environment
PART 68—CHEMICAL ACCIDENT PREVENTION PROVISIONS
Subpart F—Regulated Substances for Accidental Release Prevention


§68.130   List of substances.

(a) Regulated toxic and flammable substances under section 112(r) of the Clean Air Act are the substances listed in Tables 1, 2, 3, and 4. Threshold quantities for listed toxic and flammable substances are specified in the tables.

(b) The basis for placing toxic and flammable substances on the list of regulated substances are explained in the notes to the list.

Table 1 to §68.130—List of Regulated Toxic Substances and Threshold Quantities for Accidental Release Prevention

[Alphabetical Order—77 Substances]

Chemical name CAS No. Threshold quantity (lbs) Basis for listing
Acrolein [2-Propenal]107-02-85,000b
Acrylonitrile [2-Propenenitrile]107-13-120,000b
Acrylyl chloride [2-Propenoyl chloride]814-68-65,000b
Allyl alcohol [2-Propen-l-ol]107-18-615,000b
Allylamine [2-Propen-l-amine]107-11-910,000b
Ammonia (anhydrous)7664-41-710,000a, b
Ammonia (conc 20% or greater)7664-41-720,000a, b
Arsenous trichloride7784-34-115,000b
Arsine7784-42-11,000b
Boron trichloride [Borane, trichloro-]10294-34-55,000b
Boron trifluoride [Borane, trifluoro-]7637-07-25,000b
Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro [oxybis [metane]]-, T-4-353-42-415,000b
Bromine7726-95-610,000a, b
Carbon disulfide75-15-020,000b
Chlorine7782-50-52,500a, b
Chlorine dioxide [Chlorine oxide (ClO2)]10049-04-41,000c
Chloroform [Methane, trichloro-]67-66-320,000b
Chloromethyl ether [Methane, oxybis[chloro-]542-88-11,000b
Chloromethyl methyl ether [Methane, chloromethoxy-]107-30-25,000b
Crotonaldehyde [2-Butenal]4170-30-320,000b
Crotonaldehyde, (E)- [2-Butenal, (E)-]123-73-920,000b
Cyanogen chloride506-77-410,000c
Cyclohexylamine [Cyclohexanamine]108-91-815,000b
Diborane19287-45-72,500b
Dimethyldichlorosilane [Silane, dichlorodimethyl-]75-78-55,000b
1,1-Dimethylhydrazine [Hydrazine, 1,1-dimethyl-]57-14-715,000b
Epichlorohydrin [Oxirane, (chloromethyl)-]106-89-820,000b
Ethylenediamine [1,2-Ethanediamine]107-15-320,000b
Ethyleneimine [Aziridine]151-56-410,000b
Ethylene oxide [Oxirane]75-21-810,000a, b
Fluorine7782-41-41,000b
Formaldehyde (solution)50-00-015,000b
Furan110-00-95,000b
Hydrazine302-01-215,000b
Hydrochloric acid (conc 37% or greater)7647-01-015,000d
Hydrocyanic acid74-90-82,500a, b
Hydrogen chloride (anhydrous) [Hydrochloric acid]7647-01-05,000a
Hydrogen fluoride/Hydrofluoric acid (conc 50% or greater) [Hydrofluoric acid]7664-39-31,000a, b
Hydrogen selenide7783-07-5500b
Hydrogen sulfide7783-06-410,000a, b
Iron, pentacarbonyl- [Iron carbonyl (Fe(CO)5), (TB-5-11)-]13463-40-62,500b
Isobutyronitrile [Propanenitrile, 2-methyl-]78-82-020,000b
Isopropyl chloroformate [Carbonochloridic acid, 1-methylethyl ester]108-23-615,000b
Methacrylonitrile [2-Propenenitrile, 2-methyl-]126-98-710,000b
Methyl chloride [Methane, chloro-]74-87-310,000a
Methyl chloroformate [Carbonochloridic acid, methylester]79-22-15,000b
Methyl hydrazine [Hydrazine, methyl-]60-34-415,000b
Methyl isocyanate [Methane, isocyanato-]624-83-910,000a, b
Methyl mercaptan [Methanethiol]74-93-110,000b
Methyl thiocyanate [Thiocyanic acid, methyl ester]556-64-920,000b
Methyltrichlorosilane [Silane, trichloromethyl-]75-79-65,000b
Nickel carbonyl13463-39-31,000b
Nitric acid (conc 80% or greater)7697-37-215,000b
Nitric oxide [Nitrogen oxide (NO)]10102-43-910,000b
Oleum (Fuming Sulfuric acid) [Sulfuric acid, mixture with sulfur trioxide]18014-95-710,000e
Peracetic acid [Ethaneperoxoic acid]79-21-010,000b
Perchloromethylmercaptan [Methanesulfenyl chloride, trichloro-]594-42-310,000b
Phosgene [Carbonic dichloride]75-44-5500a, b
Phosphine7803-51-25,000b
Phosphorus oxychloride [Phosphoryl chloride]10025-87-35,000b
Phosphorus trichloride [Phosphorous trichloride]7719-12-215,000b
Piperidine110-89-415,000b
Propionitrile [Propanenitrile]107-12-010,000b
Propyl chloroformate [Carbonochloridic acid, propylester]109-61-515,000b
Propyleneimine [Aziridine, 2-methyl-]75-55-810,000b
Propylene oxide [Oxirane, methyl-]75-56-910,000b
Sulfur dioxide (anhydrous)7446-09-55,000a, b
Sulfur tetrafluoride [Sulfur fluoride (SF4), (T-4)-]7783-60-02,500b
Sulfur trioxide7446-11-910,000a, b
Tetramethyllead [Plumbane, tetramethyl-]75-74-110,000b
Tetranitromethane [Methane, tetranitro-]509-14-810,000b
Titanium tetrachloride [Titanium chloride (TiCl4) (T-4)-]7550-45-02,500b
Toluene 2,4-diisocyanate [Benzene, 2,4-diisocyanato-1-methyl-]1584-84-910,000a
Toluene 2,6-diisocyanate [Benzene, 1,3-diisocyanato-2-methyl-]191-08-710,000a
Toluene diisocyanate (unspecified isomer) [Benzene, 1,3-diisocyanatomethyl-]126471-62-510,000a
Trimethylchlorosilane [Silane, chlorotrimethyl-]75-77-410,000b
Vinyl acetate monomer [Acetic acid ethenyl ester]108-05-415,000b

1The mixture exemption in §68.115(b)(1) does not apply to the substance.

Note: Basis for Listing:

a   Mandated for listing by Congress.

b   On EHS list, vapor pressure 10 mmHg or greater.

c   Toxic gas.

d   Toxicity of hydrogen chloride, potential to release hydrogen chloride, and history of accidents.

e   Toxicity of sulfur trioxide and sulfuric acid, potential to release sulfur trioxide, and history of accidents.

Table 2 to §68.130—List of Regulated Toxic Substances and Threshold Quantities for Accidental Release Prevention

[CAS Number Order—77 Substances]

CAS No.Chemical nameThreshold quantity (lbs)Basis for listing
50-00-0Formaldehyde (solution)15,000b
57-14-71,1-Dimethylhydrazine [Hydrazine, 1,1-dimethyl-]15,000b
60-34-4Methyl hydrazine [Hydrazine, methyl-]15,000b
67-66-3Chloroform [Methane, trichloro-]20,000b
74-87-3Methyl chloride [Methane, chloro-]10,000a
74-90-8Hydrocyanic acid2,500a, b
74-93-1Methyl mercaptan [Methanethiol]10,000b
75-15-0Carbon disulfide20,000b
75-21-8Ethylene oxide [Oxirane]10,000a, b
75-44-5Phosgene [Carbonic dichloride]500a, b
75-55-8Propyleneimine [Aziridine, 2-methyl-]10,000b
75-56-9Propylene oxide [Oxirane, methyl-]10,000b
75-74-1Tetramethyllead [Plumbane, tetramethyl-]10,000b
75-77-4Trimethylchlorosilane [Silane, chlorotrimethyl-]10,000b
75-78-5Dimethyldichlorosilane [Silane, dichlorodimethyl-]5,000b
75-79-6Methyltrichlorosilane [Silane, trichloromethyl-]5,000b
78-82-0Isobutyronitrile [Propanenitrile, 2-methyl-]20,000b
79-21-0Peracetic acid [Ethaneperoxoic acid]10,000b
79-22-1Methyl chloroformate [Carbonochloridic acid, methylester]5,000b
91-08-7Toluene 2,6-diisocyanate [Benzene, 1,3-diisocyanato-2-methyl-]110,000a
106-89-8Epichlorohydrin [Oxirane, (chloromethyl)-]20,000b
107-02-8Acrolein [2-Propenal]5,000b
107-11-9Allylamine [2-Propen-1-amine]10,000b
107-12-0Propionitrile [Propanenitrile]10,000b
107-13-1Acrylonitrile [2-Propenenitrile]20,000b
107-15-3Ethylenediamine [1,2-Ethanediamine]20,000b
107-18-6Allyl alcohol [2-Propen-1-ol]15,000b
107-30-2Chloromethyl methyl ether [Methane, chloromethoxy-]5,000b
108-05-4Vinyl acetate monomer [Acetic acid ethenyl ester]15,000b
108-23-6Isopropyl chloroformate [Carbonochloridic acid, 1-methylethyl ester]15,000b
108-91-8Cyclohexylamine [Cyclohexanamine]15,000b
109-61-5Propyl chloroformate [Carbonochloridic acid, propylester]15,000b
110-00-9Furan5,000b
110-89-4Piperidine15,000b
123-73-9Crotonaldehyde, (E)- [2-Butenal, (E)-]20,000b
126-98-7Methacrylonitrile [2-Propenenitrile, 2-methyl-]10,000b
151-56-4Ethyleneimine [Aziridine]10,000b
302-01-2Hydrazine15,000b
353-42-4Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro[oxybis[methane]]-, T-4-15,000b
506-77-4Cyanogen chloride10,000c
509-14-8Tetranitromethane [Methane, tetranitro-]10,000b
542-88-1Chloromethyl ether [Methane, oxybis[chloro-]1,000b
556-64-9Methyl thiocyanate [Thiocyanic acid, methyl ester]20,000b
584-84-9Toluene 2,4-diisocyanate [Benzene, 2,4-diisocyanato-1-methyl-]110,000a
594-42-3Perchloromethylmercaptan [Methanesulfenyl chloride, trichloro-]10,000b
624-83-9Methyl isocyanate [Methane, isocyanato-]10,000a, b
814-68-6Acrylyl chloride [2-Propenoyl chloride]5,000b
4170-30-3Crotonaldehyde [2-Butenal]20,000b
7446-09-5Sulfur dioxide (anhydrous)5,000a, b
7446-11-9Sulfur trioxide10,000a, b
7550-45-0Titanium tetrachloride [Titanium chloride (TiCl4) (T-4)-]2,500b
7637-07-2Boron trifluoride [Borane, trifluoro-]5,000b
7647-01-0Hydrochloric acid (conc 37% or greater)15,000d
7647-01-0Hydrogen chloride (anhydrous) [Hydrochloric acid]5,000a
7664-39-3Hydrogen fluoride/Hydrofluoric acid (conc 50% or greater) [Hydrofluoric acid]1,000a, b
7664-41-7Ammonia (anhydrous)10,000a, b
7664-41-7Ammonia (conc 20% or greater)20,000a, b
7697-37-2Nitric acid (conc 80% or greater)15,000b
7719-12-2Phosphorus trichloride [Phosphorous trichloride]15,000b
7726-95-6Bromine10,000a, b
7782-41-4Fluorine1,000b
7782-50-5Chlorine2,500a, b
7783-06-4Hydrogen sulfide10,000a, b
7783-07-5Hydrogen selenide500b
7783-60-0Sulfur tetrafluoride [Sulfur fluoride (SF4), (T-4)-]2,500b
7784-34-1Arsenous trichloride15,000b
7784-42-1Arsine1,000b
7803-51-2Phosphine5,000b
8014-95-7Oleum (Fuming Sulfuric acid) [Sulfuric acid, mixture with sulfur trioxide]110,000e
10025-87-3Phosphorus oxychloride [Phosphoryl chloride]5,000b
10049-04-4Chlorine dioxide [Chlorine oxide (ClO2)]1,000c
10102-43-9Nitric oxide [Nitrogen oxide (NO)]10,000b
10294-34-5Boron trichloride [Borane, trichloro-]5,000b
13463-39-3Nickel carbonyl1,000b
13463-40-6Iron, pentacarbonyl- [Iron carbonyl (Fe(CO)5), (TB-5-11)-]2,500b
19287-45-7Diborane2,500b
26471-62-5Toluene diisocyanate (unspecified isomer) [Benzene, 1,3-diisocyanatomethyl-1]110,000a

1The mixture exemption in §68.115(b)(1) does not apply to the substance.

Note: Basis for Listing:

a   Mandated for listing by Congress.

b   On EHS list, vapor pressure 10 mmHg or greater.

c   Toxic gas.

d   Toxicity of hydrogen chloride, potential to release hydrogen chloride, and history of accidents.

e   Toxicity of sulfur trioxide and sulfuric acid, potential to release sulfur trioxide, and history of accidents.

Table 3 to §68.130—List of Regulated Flammable Substances1 and Threshold Quantities for Accidental Release Prevention

[Alphabetical Order—63 Substances]

Chemical name CAS No. Threshold quantity (lbs) Basis for listing
Acetaldehyde75-07-010,000g
Acetylene [Ethyne]74-86-210,000f
Bromotrifluorethylene [Ethene, bromotrifluoro-]598-73-210,000f
1,3-Butadiene106-99-010,000f
Butane106-97-810,000f
1-Butene106-98-910,000f
2-Butene107-01-710,000f
Butene25167-67-310,000f
2-Butene-cis590-18-110,000f
2-Butene-trans [2-Butene, (E)]624-64-610,000f
Carbon oxysulfide [Carbon oxide sulfide (COS)]463-58-110,000f
Chlorine monoxide [Chlorine oxide]7791-21-110,000f
2-Chloropropylene [1-Propene, 2-chloro-]557-98-210,000g
1-Chloropropylene [1-Propene, 1-chloro-]590-21-610,000g
Cyanogen [Ethanedinitrile]460-19-510,000f
Cyclopropane75-19-410,000f
Dichlorosilane [Silane, dichloro-]4109-96-010,000f
Difluoroethane [Ethane, 1,1-difluoro-]75-37-610,000f
Dimethylamine [Methanamine, N-methyl-]124-40-310,000f
2,2-Dimethylpropane [Propane, 2,2-dimethyl-]463-82-110,000f
Ethane74-84-010,000f
Ethyl acetylene [1-Butyne]107-00-610,000f
Ethylamine [Ethanamine]75-04-710,000f
Ethyl chloride [Ethane, chloro-]75-00-310,000f
Ethylene [Ethene]74-85-110,000f
Ethyl ether [Ethane, 1,1′-oxybis-]60-29-710,000g
Ethyl mercaptan [Ethanethiol]75-08-110,000g
Ethyl nitrite [Nitrous acid, ethyl ester]109-95-510,000f
Hydrogen1333-74-010,000f
Isobutane [Propane, 2-methyl]75-28-510,000f
Isopentane [Butane, 2-methyl-]78-78-410,000g
Isoprene [1,3-Butadinene, 2-methyl-]78-79-510,000g
Isopropylamine [2-Propanamine]75-31-010,000g
Isopropyl chloride [Propane, 2-chloro-]75-29-610,000g
Methane74-82-810,000f
Methylamine [Methanamine]74-89-510,000f
3-Methyl-1-butene563-45-110,000f
2-Methyl-1-butene563-46-210,000g
Methyl ether [Methane, oxybis-]115-10-610,000f
Methyl formate [Formic acid, methyl ester]107-31-310,000g
2-Methylpropene [1-Propene, 2-methyl-]115-11-710,000f
1,3-Pentadinene504-60-910,000f
Pentane109-66-010,000g
1-Pentene109-67-110,000g
2-Pentene, (E)-646-04-810,000g
2-Pentene, (Z)-627-20-310,000g
Propadiene [1,2-Propadiene]463-49-010,000f
Propane74-98-610,000f
Propylene [1-Propene]115-07-110,000f
Propyne [1-Propyne]74-99-710,000f
Silane7803-62-510,000f
Tetrafluoroethylene [Ethene, tetrafluoro-]116-14-310,000f
Tetramethylsilane [Silane, tetramethyl-]75-76-310,000g
Trichlorosilane [Silane, trichloro-]10025-78-210,000g
Trifluorochloroethylene [Ethene, chlorotrifluoro-]79-38-910,000f
Trimethylamine [Methanamine, N,N-dimethyl-]75-50-310,000f
Vinyl acetylene [1-Buten-3-yne]689-97-410,000f
Vinyl chloride [Ethene, chloro-]75-01-410,000a, f
Vinyl ethyl ether [Ethene, ethoxy-]109-92-210,000g
Vinyl fluoride [Ethene, fluoro-]75-02-510,000f
Vinylidene chloride [Ethene, 1,1-dichloro-]75-35-410,000g
Vinylidene fluoride [Ethene, 1,1-difluoro-]75-38-710,000f
Vinyl methyl ether [Ethene, methoxy-]107-25-510,000f

1A flammable substance when used as a fuel or held for sale as a fuel at a retail facility is excluded from all provisions of this part (see §68.126).

Note: Basis for Listing:

   aMandated for listing by Congress.

   fFlammable gas.

   gVolatile flammable liquid.

Table 4 to §68.130—List of Regulated Flammable Substances1 and Threshold Quantities for Accidental Release Prevention

[CAS Number Order—63 Substances]

CAS No.Chemical nameThreshold quantity
(lbs)
Basis for listing
60-29-7Ethyl ether [Ethane, 1,1-oxybis-]10,000g
74-82-8Methane10,000f
74-84-0Ethane10,000f
74-85-1Ethylene [Ethene]10,000f
74-86-2Acetylene [Ethyne]10,000f
74-89-5Methylamine [Methanamine]10,000f
74-98-6Propane10,000f
74-99-7Propyne [1-Propyne]10,000f
75-00-3Ethyl chloride [Ethane, chloro-]10,000f
75-01-4Vinyl chloride [Ethene, chloro-]10,000a, f
75-02-5Vinyl fluoride [Ethene, fluoro-]10,000f
75-04-7Ethylamine [Ethanamine]10,000f
75-07-0Acetaldehyde10,000g
75-08-1Ethyl mercaptan [Ethanethiol]10,000g
75-19-4Cyclopropane10,000f
75-28-5Isobutane [Propane, 2-methyl]10,000f
75-29-6Isopropyl chloride [Propane, 2-chloro-]10,000g
75-31-0Isopropylamine [2-Propanamine]10,000g
75-35-4Vinylidene chloride [Ethene, 1,1-dichloro-]10,000g
75-37-6Difluoroethane [Ethane, 1,1-difluoro-]10,000f
75-38-7Vinylidene fluoride [Ethene, 1,1-difluoro-]10,000f
75-50-3Trimethylamine [Methanamine, N, N-dimethyl-]10,000f
75-76-3Tetramethylsilane [Silane, tetramethyl-]10,000g
78-78-4Isopentane [Butane, 2-methyl-]10,000g
78-79-5Isoprene [1,3,-Butadiene, 2-methyl-]10,000g
79-38-9Trifluorochloroethylene [Ethene, chlorotrifluoro-]10,000f
106-97-8Butane10,000f
106-98-91-Butene10,000f
106-99-01,3-Butadiene10,000f
107-00-6Ethyl acetylene [1-Butyne]10,000f
107-01-72-Butene10,000f
107-25-5Vinyl methyl ether [Ethene, methoxy-]10,000f
107-31-3Methyl formate [Formic acid, methyl ester]10,000g
109-66-0Pentane10,000g
109-67-11-Pentene10,000g
109-92-2Vinyl ethyl ether [Ethene, ethoxy-]10,000g
109-95-5Ethyl nitrite [Nitrous acid, ethyl ester]10,000f
115-07-1Propylene [1-Propene]10,000f
115-10-6Methyl ether [Methane, oxybis-]10,000f
115-11-72-Methylpropene [1-Propene, 2-methyl-]10,000f
116-14-3Tetrafluoroethylene [Ethene, tetrafluoro-]10,000f
124-40-3Dimethylamine [Methanamine, N-methyl-]10,000f
460-19-5Cyanogen [Ethanedinitrile]10,000f
463-49-0Propadiene [1,2-Propadiene]10,000f
463-58-1Carbon oxysulfide [Carbon oxide sulfide (COS)]10,000f
463-82-12,2-Dimethylpropane [Propane, 2,2-dimethyl-]10,000f
504-60-91,3-Pentadiene10,000f
557-98-22-Chloropropylene [1-Propene, 2-chloro-]10,000g
563-45-13-Methyl-1-butene10,000f
563-46-22-Methyl-1-butene10,000g
590-18-12-Butene-cis10,000f
590-21-61-Chloropropylene [1-Propene, 1-chloro-]10,000g
598-73-2Bromotrifluorethylene [Ethene, bromotrifluoro-]10,000f
624-64-62-Butene-trans [2-Butene, (E)]10,000f
627-20-32-Pentene, (Z)-10,000g
646-04-82-Pentene, (E)-10,000g
689-97-4Vinyl acetylene [1-Buten-3-yne]10,000f
1333-74-0Hydrogen10,000f
4109-96-0Dichlorosilane [Silane, dichloro-]10,000f
7791-21-1Chlorine monoxide [Chlorine oxide]10,000f
7803-62-5Silane10,000f
10025-78-2Trichlorosilane [Silane, trichloro-]10,000g
25167-67-3Butene10,000f

1A flammable substance when used as a fuel or held for sale as a fuel at a retail facility is excluded from all provisions of this part (see §68.126).

Note: Basis for Listing:

aMandated for listing by Congress.

fFlammable gas.

gVolatile flammable liquid.

[59 FR 4493, Jan. 31, 1994. Redesignated at 61 FR 31717, June 20, 1996, as amended at 62 FR 45132, Aug. 25, 1997; 63 FR 645, Jan. 6, 1998; 65 FR 13250, Mar. 13, 2000; 82 FR 4702, Jan. 13, 2017]

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