40 C.F.R. Appendix A to Part 355
The List of Extremely Hazardous Substances and Their Threshold Planning Quantities
Cite as 40 C.F.R. Appendix A to Part 355 (2026)
[Alphabetical Order] CAS No. Chemical name Notes Reportable quantity * (pounds) Threshold planning quantity (pounds) 75-86-5 Acetone Cyanohydrin 10 1,000 1752-30-3 Acetone Thiosemicarbazide 1,000 1,000/10,000 107-02-8 Acrolein 1 500 79-06-1 Acrylamide f 5,000 1,000/10,000 107-13-1 Acrylonitrile f 100 10,000 814-68-6 Acrylyl Chloride d 100 100 111-69-3 Adiponitrile f 1,000 1,000 116-06-3 Aldicarb b 1 100/10,000 309-00-2 Aldrin 1 500/10,000 107-18-6 Allyl Alcohol 100 1,000 107-11-9 Allylamine 500 500 20859-73-8 Aluminum Phosphide a 100 500 54-62-6 Aminopterin 500 500/10,000 78-53-5 Amiton 500 500 3734-97-2 Amiton Oxalate 100 100/10,000 7664-41-7 Ammonia f 100 500 300-62-9 Amphetamine 1,000 1,000 62-53-3 Aniline f 5,000 1,000 88-05-1 Aniline, 2,4,6-Trimethyl- 500 500 7783-70-2 Antimony Pentafluoride 500 500 1397-94-0 Antimycin A b 1,000 1,000/10,000 86-88-4 ANTU 100 500/10,000 1303-28-2 Arsenic Pentoxide 1 100/10,000 1327-53-3 Arsenous Oxide d 1 100/10,000 7784-34-1 Arsenous Trichloride 1 500 7784-42-1 Arsine 100 100 2642-71-9 Azinphos-Ethyl 100 100/10,000 86-50-0 Azinphos-Methyl 1 10/10,000 98-87-3 Benzal Chloride 5,000 500 98-16-8 Benzenamine, 3-(Trifluoromethyl)- 500 500 100-14-1 Benzene, 1-(Chloromethyl)-4-Nitro- 500 500/10,000 98-05-5 Benzenearsonic Acid 10 10/10,000 3615-21-2 Benzimidazole, 4,5-Dichloro-2-(Trifluoromethyl)- c 500 500/10,000 98-07-7 Benzotrichloride 10 100 100-44-7 Benzyl Chloride 100 500 140-29-4 Benzyl Cyanide d 500 500 15271-41-7 Bicyclo[2.2.1]Heptane-2-Carbonitrile, 5-Chloro-6-((((Methylamino)Carbonyl)Oxy)Imino)-, (1s-(1-alpha,2-beta,4-alpha,5-alpha,6E))- 500 500/10,000 534-07-6 Bis(Chloromethyl) Ketone 10 10/10,000 4044-65-9 Bitoscanate 500 500/10,000 10294-34-5 Boron Trichloride 500 500 7637-07-2 Boron Trifluoride 500 500 353-42-4 Boron Trifluoride Compound With Methyl Ether (1:1) 1,000 1,000 28772-56-7 Bromadiolone 100 100/10,000 7726-95-6 Bromine f 500 500 1306-19-0 Cadmium Oxide 100 100/10,000 2223-93-0 Cadmium Stearate b 1,000 1,000/10,000 7778-44-1 Calcium Arsenate 1 500/10,000 8001-35-2 Camphechlor 1 500/10,000 56-25-7 Cantharidin 100 100/10,000 51-83-2 Carbachol Chloride 500 500/10,000 26419-73-8 Carbamic Acid, Methyl-, O-(((2,4-Dimethyl-1, 3-Dithiolan-2-yl)Methylene)Amino)- 100 100/10,000 1563-66-2 Carbofuran 10 10/10,000 75-15-0 Carbon Disulfide f 100 10,000 786-19-6 Carbophenothion 500 500 57-74-9 Chlordane 1 1,000 470-90-6 Chlorfenvinfos 500 500 7782-50-5 Chlorine 10 100 24934-91-6 Chlormephos 500 500 999-81-5 Chlormequat Chloride d 100 100/10,000 79-11-8 Chloroacetic Acid 100 100/10,000 107-07-3 Chloroethanol 500 500 627-11-2 Chloroethyl Chloroformate 1,000 1,000 67-66-3 Chloroform f 10 10,000 542-88-1 Chloromethyl Ether d 10 100 107-30-2 Chloromethyl Methyl Ether b 10 100 3691-35-8 Chlorophacinone 100 100/10,000 1982-47-4 Chloroxuron 500 500/10,000 21923-23-9 Chlorthiophos d 500 500 10025-73-7 Chromic Chloride 1 1/10,000 62207-76-5 Cobalt, ((2,2′-(1,2-Ethanediylbis (Nitrilomethylidyne)) Bis(6-Fluorophenolato))(2-)-N,N′,O,O′)- 100 100/10,000 10210-68-1 Cobalt Carbonyl d 10 10/10,000 64-86-8 Colchicine d 10 10/10,000 56-72-4 Coumaphos 10 100/10,000 5836-29-3 Coumatetralyl 500 500/10,000 95-48-7 Cresol, o- 100 1,000/10,000 535-89-7 Crimidine 100 100/10,000 4170-30-3 Crotonaldehyde 100 1,000 123-73-9 Crotonaldehyde, (E)- 100 1,000 506-68-3 Cyanogen Bromide 1,000 500/10,000 506-78-5 Cyanogen Iodide 1,000 1,000/10,000 2636-26-2 Cyanophos 1,000 1,000 675-14-9 Cyanuric Fluoride 100 100 66-81-9 Cycloheximide 100 100/10,000 108-91-8 Cyclohexylamine f 10,000 10,000 17702-41-9 Decaborane(14) 500 500/10,000 8065-48-3 Demeton 500 500 919-86-8 Demeton-S-Methyl 500 500 10311-84-9 Dialifor 100 100/10,000 19287-45-7 Diborane 100 100 111-44-4 Dichloroethyl ether 10 10,000 149-74-6 Dichloromethylphenylsilane 1,000 1,000 62-73-7 Dichlorvos 10 1,000 141-66-2 Dicrotophos 100 100 1464-53-5 Diepoxybutane 10 500 814-49-3 Diethyl Chlorophosphate d 500 500 71-63-6 Digitoxin b 100 100/10,000 2238-07-5 Diglycidyl Ether 1,000 1,000 20830-75-5 Digoxin d 10 10/10,000 115-26-4 Dimefox 500 500 60-51-5 Dimethoate 10 500/10,000 2524-03-0 Dimethyl Phosphorochloridothioate 500 500 77-78-1 Dimethyl sulfate 100 500 75-78-5 Dimethyldichlorosilane d 500 500 57-14-7 Dimethylhydrazine 10 1,000 99-98-9 Dimethyl-p-Phenylenediamine 10 10/10,000 644-64-4 Dimetilan 1 500/10,000 534-52-1 Dinitrocresol 10 10/10,000 88-85-7 Dinoseb 1,000 100/10,000 1420-07-1 Dinoterb 500 500/10,000 78-34-2 Dioxathion 500 500 82-66-6 Diphacinone 10 10/10,000 152-16-9 Diphosphoramide, Octamethyl- 100 100 298-04-4 Disulfoton 1 500 514-73-8 Dithiazanine Iodide 500 500/10,000 541-53-7 Dithiobiuret 100 100/10,000 316-42-7 Emetine, Dihydrochloride d 1 1/10,000 115-29-7 Endosulfan 1 10/10,000 2778-04-3 Endothion 500 500/10,000 72-20-8 Endrin 1 500/10,000 106-89-8 Epichlorohydrin f 100 1,000 2104-64-5 EPN 100 100/10,000 50-14-6 Ergocalciferol b 1,000 1,000/10,000 379-79-3 Ergotamine Tartrate 500 500/10,000 1622-32-8 Ethanesulfonyl Chloride, 2-Chloro- 500 500 10140-87-1 Ethanol, 1,2-Dichloro-, Acetate 1,000 1,000 563-12-2 Ethion 10 1,000 13194-48-4 Ethoprophos 1,000 1,000 538-07-8 Ethylbis(2-Chloroethyl)Amine d 500 500 371-62-0 Ethylene Fluorohydrin b, d 10 10 75-21-8 Ethylene Oxide f 10 1,000 107-15-3 Ethylenediamine 5,000 10,000 151-56-4 Ethyleneimine 1 500 542-90-5 Ethylthiocyanate 10,000 10,000 22224-92-6 Fenamiphos 10 10/10,000 115-90-2 Fensulfothion d 500 500 4301-50-2 Fluenetil 100 100/10,000 7782-41-4 Fluorine e 10 500 640-19-7 Fluoroacetamide 100 100/10,000 144-49-0 Fluoroacetic Acid 10 10/10,000 359-06-8 Fluoroacetyl Chloride b 10 10 51-21-8 Fluorouracil 500 500/10,000 944-22-9 Fonofos 500 500 50-00-0 Formaldehyde f 100 500 107-16-4 Formaldehyde Cyanohydrin d 1,000 1,000 23422-53-9 Formetanate Hydrochloride d 100 500/10,000 2540-82-1 Formothion 100 100 17702-57-7 Formparanate 100 100/10,000 21548-32-3 Fosthietan 500 500 3878-19-1 Fuberidazole 100 100/10,000 110-00-9 Furan 100 500 13450-90-3 Gallium Trichloride 500 500/10,000 77-47-4 Hexachlorocyclopentadiene d 10 100 4835-11-4 Hexamethylenediamine, N,N′-Dibutyl- 500 500 302-01-2 Hydrazine 1 1,000 74-90-8 Hydrocyanic Acid 10 100 7647-01-0 Hydrogen Chloride (gas only) f 5,000 500 7664-39-3 Hydrogen Fluoride 100 100 7722-84-1 Hydrogen Peroxide (Conc >52%) f 1,000 1,000 7783-07-5 Hydrogen Selenide 10 10 7783-06-4 Hydrogen Sulfide f 100 500 123-31-9 Hydroquinone f 100 500/10,000 13463-40-6 Iron, Pentacarbonyl- 100 100 297-78-9 Isobenzan 100 100/10,000 78-82-0 Isobutyronitrile d 1,000 1,000 102-36-3 Isocyanic Acid, 3,4-Dichlorophenyl Ester 500 500/10,000 465-73-6 Isodrin 1 100/10,000 55-91-4 Isofluorphate b 100 100 4098-71-9 Isophorone Diisocyanate g 500 500 108-23-6 Isopropyl Chloroformate 1,000 1,000 119-38-0 Isopropylmethyl-pyrazolyl Dimethylcarbamate 100 500 78-97-7 Lactonitrile 1,000 1,000 21609-90-5 Leptophos 500 500/10,000 541-25-3 Lewisite b, d 10 10 58-89-9 Lindane 1 1,000/10,000 7580-67-8 Lithium Hydride a 100 100 109-77-3 Malononitrile 1,000 500/10,000 12108-13-3 Manganese, Tricarbonyl Methylcyclopentadienyl d 100 100 51-75-2 Mechlorethamine b 10 10 950-10-7 Mephosfolan 500 500 1600-27-7 Mercuric Acetate 500 500/10,000 7487-94-7 Mercuric Chloride 500 500/10,000 21908-53-2 Mercuric Oxide 500 500/10,000 10476-95-6 Methacrolein Diacetate 1,000 1,000 760-93-0 Methacrylic Anhydride 500 500 126-98-7 Methacrylonitrile d 1,000 500 920-46-7 Methacryloyl Chloride 100 100 30674-80-7 Methacryloyloxyethyl Isocyanate d 100 100 10265-92-6 Methamidophos 100 100/10,000 558-25-8 Methanesulfonyl Fluoride 1,000 1,000 950-37-8 Methidathion 500 500/10,000 2032-65-7 Methiocarb 10 500/10,000 16752-77-5 Methomyl d 100 500/10,000 151-38-2 Methoxyethylmercuric Acetate 500 500/10,000 80-63-7 Methyl 2-Chloroacrylate 500 500 74-83-9 Methyl Bromide f 1,000 1,000 79-22-1 Methyl Chloroformate d 1,000 500 60-34-4 Methyl Hydrazine 10 500 624-83-9 Methyl Isocyanate 10 500 556-61-6 Methyl Isothiocyanate a 500 500 74-93-1 Methyl Mercaptan f 100 500 3735-23-7 Methyl Phenkapton 500 500 676-97-1 Methyl Phosphonic Dichloride a 100 100 556-64-9 Methyl Thiocyanate 10,000 10,000 78-94-4 Methyl Vinyl Ketone 10 10 502-39-6 Methylmercuric Dicyanamide 500 500/10,000 75-79-6 Methyltrichlorosilane d 500 500 1129-41-5 Metolcarb 1,000 100/10,000 7786-34-7 Mevinphos 10 500 315-18-4 Mexacarbate d 1,000 500/10,000 50-07-7 Mitomycin C 10 500/10,000 6923-22-4 Monocrotophos 10 10/10,000 2763-96-4 Muscimol 1,000 500/10,000 505-60-2 Mustard Gas d 500 500 13463-39-3 Nickel Carbonyl 10 1 54-11-5 Nicotine b 100 100 65-30-5 Nicotine Sulfate 100 100/10,000 7697-37-2 Nitric Acid 1,000 1,000 10102-43-9 Nitric Oxide b 10 100 98-95-3 Nitrobenzene f 1,000 10,000 1122-60-7 Nitrocyclohexane 500 500 10102-44-0 Nitrogen Dioxide 10 100 62-75-9 Nitrosodimethylamine d 10 1,000 991-42-4 Norbormide 100 100/10,000 Organorhodium Complex (PMN-82-147) 10 10/10,000 630-60-4 Ouabain b 100 100/10,000 23135-22-0 Oxamyl 100 100/10,000 78-71-7 Oxetane, 3,3-Bis(Chloromethyl)- 500 500 2497-07-6 Oxydisulfoton d 500 500 10028-15-6 Ozone 100 100 1910-42-5 Paraquat Dichloride 10 10/10,000 2074-50-2 Paraquat Methosulfate 10 10/10,000 56-38-2 Parathion b 10 100 298-00-0 Parathion-Methyl b 100 100/10,000 12002-03-8 Paris Green 1 500/10,000 19624-22-7 Pentaborane 500 500 2570-26-5 Pentadecylamine 100 100/10,000 79-21-0 Peracetic Acid 500 500 594-42-3 Perchloromethylmercaptan 100 500 108-95-2 Phenol 1,000 500/10,000 4418-66-0 Phenol, 2,2′-Thiobis(4-Chloro-6-Methyl)- 100 100/10,000 64-00-6 Phenol, 3-(1-Methylethyl)-, Methylcarbamate 10 500/10,000 58-36-6 Phenoxarsine, 10,10′-Oxydi- 500 500/10,000 696-28-6 Phenyl Dichloroarsine d 1 500 59-88-1 Phenylhydrazine Hydrochloride 1,000 1,000/10,000 62-38-4 Phenylmercury Acetate 100 500/10,000 2097-19-0 Phenylsilatrane d 100 100/10,000 103-85-5 Phenylthiourea 100 100/10,000 298-02-2 Phorate 10 10 4104-14-7 Phosacetim 100 100/10,000 947-02-4 Phosfolan 100 100/10,000 75-44-5 Phosgene f 10 10 13171-21-6 Phosphamidon 100 100 7803-51-2 Phosphine 100 500 2703-13-1 Phosphonothioic Acid, Methyl-, O-Ethyl O-(4-(Methylthio) Phenyl) Ester 500 500 50782-69-9 Phosphonothioic Acid, Methyl-, S-(2-(Bis(1Methylethyl)Amino)Ethyl) O-Ethyl Ester 100 100 2665-30-7 Phosphonothioic Acid, Methyl-, O-(4-Nitrophenyl) O-Phenyl Ester 500 500 3254-63-5 Phosphoric Acid, Dimethyl 4-(Methylthio)Phenyl Ester 500 500 2587-90-8 Phosphorothioic Acid, O,O-Dimethyl-S-(2-Methylthio) Ethyl Ester b, c 500 500 7723-14-0 Phosphorus a, d 1 100 10025-87-3 Phosphorus Oxychloride 1,000 500 10026-13-8 Phosphorus Pentachloride a 500 500 7719-12-2 Phosphorus Trichloride 1,000 1,000 57-47-6 Physostigmine 100 100/10,000 57-64-7 Physostigmine, Salicylate (1:1) 100 100/10,000 124-87-8 Picrotoxin 500 500/10,000 110-89-4 Piperidine 1,000 1,000 23505-41-1 Pirimifos-Ethyl 1,000 1,000 10124-50-2 Potassium Arsenite 1 500/10,000 151-50-8 Potassium Cyanide a 10 100 506-61-6 Potassium Silver Cyanide a 1 500 2631-37-0 Promecarb d 1,000 500/10,000 106-96-7 Propargyl Bromide 10 10 57-57-8 Propiolactone, Beta- 10 500 107-12-0 Propionitrile 10 500 542-76-7 Propionitrile, 3-Chloro- 1,000 1,000 70-69-9 Propiophenone, 4-Amino- c 100 100/10,000 109-61-5 Propyl Chloroformate 500 500 75-56-9 Propylene Oxide f 100 10,000 75-55-8 Propyleneimine 1 10,000 2275-18-5 Prothoate 100 100/10,000 129-00-0 Pyrene b 5,000 1,000/10,000 140-76-1 Pyridine, 2-Methyl-5-Vinyl- 500 500 504-24-5 Pyridine, 4-Amino- d 1,000 500/10,000 1124-33-0 Pyridine, 4-Nitro-,l-Oxide 500 500/10,000 53558-25-1 Pyriminil d 100 100/10,000 14167-18-1 Salcomine 500 500/10,000 107-44-8 Sarin d 10 10 7783-00-8 Selenious Acid 10 1,000/10,000 7791-23-3 Selenium Oxychloride 500 500 563-41-7 Semicarbazide Hydrochloride 1,000 1,000/10,000 3037-72-7 Silane, (4-Aminobutyl)Diethoxymethyl- 1,000 1,000 7631-89-2 Sodium Arsenate 1 1,000/10,000 7784-46-5 Sodium Arsenite 1 500/10,000 26628-22-8 Sodium Azide (Na(N 3 )) a 1,000 500 124-65-2 Sodium Cacodylate 100 100/10,000 143-33-9 Sodium Cyanide (Na(CN)) a 10 100 62-74-8 Sodium Fluoroacetate 10 10/10,000 13410-01-0 Sodium Selenate 100 100/10,000 10102-18-8 Sodium Selenite d 100 100/10,000 10102-20-2 Sodium Tellurite 500 500/10,000 900-95-8 Stannane, Acetoxytriphenyl- c 500 500/10,000 57-24-9 Strychnine b 10 100/10,000 60-41-3 Strychnine Sulfate 10 100/10,000 3689-24-5 Sulfotep 100 500 3569-57-1 Sulfoxide, 3-Chloropropyl Octyl 500 500 7446-09-5 Sulfur Dioxide f 500 500 7783-60-0 Sulfur Tetrafluoride 100 100 7446-11-9 Sulfur Trioxide a 100 100 7664-93-9 Sulfuric Acid 1,000 1,000 77-81-6 Tabun b, d 10 10 7783-80-4 Tellurium Hexafluoride e 100 100 107-49-3 TEPP 10 100 13071-79-9 Terbufos d 100 100 78-00-2 Tetraethyllead b 10 100 597-64-8 Tetraethyltin b 100 100 75-74-1 Tetramethyllead b, f 100 100 509-14-8 Tetranitromethane 10 500 10031-59-1 Thallium Sulfate d 100 100/10,000 6533-73-9 Thallous Carbonate b, d 100 100/10,000 7791-12-0 Thallous Chloride b, d 100 100/10,000 2757-18-8 Thallous Malonate b, d 100 100/10,000 7446-18-6 Thallous Sulfate 100 100/10,000 2231-57-4 Thiocarbazide 1,000 1,000/10,000 39196-18-4 Thiofanox 100 100/10,000 297-97-2 Thionazin 100 500 108-98-5 Thiophenol 100 500 79-19-6 Thiosemicarbazide 100 100/10,000 5344-82-1 Thiourea, (2-Chlorophenyl)- 100 100/10,000 614-78-8 Thiourea, (2-Methylphenyl)- 500 500/10,000 7550-45-0 Titanium Tetrachloride 1,000 100 584-84-9 Toluene 2,4-Diisocyanate 100 500 91-08-7 Toluene 2,6-Diisocyanate 100 100 110-57-6 Trans-1,4-Dichlorobutene 500 500 1031-47-6 Triamiphos 500 500/10,000 24017-47-8 Triazofos 500 500 76-02-8 Trichloroacetyl Chloride 500 500 115-21-9 Trichloroethylsilane d 500 500 327-98-0 Trichloronate e 500 500 98-13-5 Trichlorophenylsilane d 500 500 1558-25-4 Trichloro(Chloromethyl)Silane 100 100 27137-85-5 Trichloro(Dichlorophenyl) Silane 500 500 998-30-1 Triethoxysilane 500 500 75-77-4 Trimethylchlorosilane 1,000 1,000 824-11-3 Trimethylolpropane Phosphite d 100 100/10,000 1066-45-1 Trimethyltin Chloride 500 500/10,000 639-58-7 Triphenyltin Chloride 500 500/10,000 555-77-1 Tris(2-Chloroethyl)Amine d 100 100 2001-95-8 Valinomycin b 1,000 1,000/10,000 1314-62-1 Vanadium Pentoxide 1,000 100/10,000 108-05-4 Vinyl Acetate Monomer f 5,000 1,000 81-81-2 Warfarin 100 500/10,000 129-06-6 Warfarin Sodium d 100 100/10,000 28347-13-9 Xylylene Dichloride 100 100/10,000 58270-08-9 Zinc, Dichloro(4,4-Dimethyl-5((((Methylamino)Carbonyl) Oxy)Imino)Pentanenitrile)-, (T-4)- 100 100/10,000 1314-84-7 Zinc Phosphide a 100 500 * Only the statutory or final RQ is shown. For more information, see 40 CFR 355.61. Notes: a. This material is a reactive solid. The TPQ does not default to 10,000 pounds for non-powder, non-molten, non-solution form. b. The calculated TPQ changed after technical review as described in a technical support document for the final rule, April 22, 1987. c. Chemicals added by final rule, April 22, 1987. d. Revised TPQ based on new or re-evaluated toxicity data, April 22, 1987. e. The TPQ was revised due to calculation error, April 22, 1987. f. Chemicals on the original list that do not meet toxicity criteria but because of their acute lethality, high production volume and known risk are considered chemicals of concern (“Other chemicals”), November 17, 1986 and February 15, 1990. g. The TPQ was recalculated (September 8, 2003) since it was mistakenly calculated in the April 22, 1987 final rule under the wrong assumption that this chemical is a reactive solid, when in fact it is a liquid. RQ for this chemical was adjusted on September 11, 2006.
- Cross-references to the CFR
- 40:355.61.