Health hazard · Respiratory sensitisation
H334 — May cause allergy or asthma symptoms or breathing difficulties if inhaled
Health hazard statements describe what the substance does to a person exposed to it. 118 substances with a harmonised EU classification carry this code.
EU CLP: currentUS OSHA HazCom: currentUS HazCom 2012: currentUN GHS: current
01 · Wording
What H334 says
Official
May cause allergy or asthma symptoms or breathing difficulties if inhaled.
Source
CLP Annex III · Health hazards
Classification 
Respiratory sensitisation GHS chapter 3.4
Category 1B, 1A, 1 · pictogram GHS08 (health hazard) · signal word Danger
UN GHS history
Unchanged since 2009.
Rev.3 2009
Rev.4 2011
Rev.5 2013
Rev.6 2015
Rev.7 2017
Rev.8 2019
Rev.9 2021
Rev.10 2023
Rev.11 2025
wording never changed
Present in every UN GHS edition from Rev.3 (2009) to Rev.11 (2025), with the same wording throughout.
Nine editions of the UN model text, 86 hazard statements, 19 of which ever moved. Read the full story in what changed in UN GHS Rev.11.
02 · Legal status
Where H334 is current
GHS is a United Nations model text, revised every two years, and each jurisdiction adopts a revision on its own timetable. A code can be legally current in one system and deleted in another — that is normal, not an error.
| Jurisdiction | Basis | Status of H334 |
|---|---|---|
| EU CLP | Regulation (EC) 1272/2008 CLP Annex IV, Part 2 (consolidated) | Current |
| US OSHA HazCom | 29 CFR 1910.1200 Appendix C UN GHS Rev.7 (final rule of 20 May 2024) | Current |
| US HazCom 2012 | legacy · GHS Rev.3 UN GHS Rev.3, Annex 3 | Current |
| UN GHS | Rev.11 (2025) UN GHS Rev.11, Annex 3 | Current |
Currently in force under: EU CLP, US OSHA HazCom, US HazCom 2012, UN GHS. Sources: EU CLP · US OSHA HazCom · US HazCom 2012 · UN GHS
03 · Substances
Substances carrying H334
Every entry whose harmonised CLP Annex VI classification includes this hazard statement. Substances with a reference page here open on this site; the rest open on ghssymbols.com. Of these, 8 are group entries such as “salts of picric acid” or “beryllium compounds” — Annex VI gives them no CAS number, so they are listed by Index No and have no page of their own.
- (1S,3S,5R,6R)-(4-nitrophenylmethyl)-1-dioxo-6-phenylacetamido-penam-3-carboxylate CAS 54275-93-3
- (1S,4R,6R,7R)-(4-nitrophenylmethyl)3-methylene-1-oxo-7-phenylacetamido-cepham-4-carboxylateido-penam-3-carboxylate CAS 76109-32-5
- 1,2,3,6-tetrahydrophthalic anhydride [1]; cis-1,2,3,6-tetrahydrophthalic anhydride [2]; 3,4,5,6-tetrahydrophthalic anhydride [3]; tetrahydrophthalic anhydride [4] CAS 85-43-8[1]935-79-5[2
- 1,3-bis(1-isocyanato-1-methylethyl)benzene; [m-TMXDI] CAS 2778-42-9
- 1,5-naphthylene diisocyanate; [containing < 0.1 % (w/w) of particles with an aerodynamic diameter of below 50 µm] CAS 3173-72-6
- 2-(3-(prop-1-en-2-yl)phenyl)prop-2-yl isocyanate CAS 2094-99-7
- 2-(isocyanatosulfonylmethyl)benzoic acid methyl ester; (alt.):methyl 2-(isocyanatosulfonylmethyl)benzoate CAS 83056-32-0
- 2-phenylethylisocyanate CAS 1943-82-4
- 2,2,4-trimethylhexamethylene-1,6-di-isocyanate [1]; 2,4,4-trimethylhexamethylene-1,6-di-isocyanate [2] CAS 16938-22-0[1]15646-9
- 2,4,6-triisopropyl-m-phenylene diisocyanate CAS 2162-73-4
- 2,5-bis-isocyanatomethyl-bicyclo[2.2.1]heptane Index No 615-029-00-X
- 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate; isophorone di-isocyanate CAS 4098-71-9
- 3,3'-dimethylbiphenyl–4,4'-diyl diisocyanate CAS 91-97-4
- 4-chlorophenylisocyanate CAS 104-12-1
- 4-isocyanatosulphonyltoluene; tosyl isocyanate CAS 4083-64-1
- 4,4'-methylenedi(cyclohexyl isocyanate); dicyclohexylmethane-4,4'-di-isocyanate CAS 5124-30-1
- 7-amino-3-((5-carboxymethyl-4-methyl-1,3-thiazol-2-ylthio)methyl)-8-oxo-5-thia-1-azabicyclo(4.2.0)oct-2-ene-2-carboxylic acid CAS 111298-82-9
- 8,9-dinorborn-5-ene-2,3-dicarboxylic anhydride CAS 123748-85-6
- 8,9,10-trinorborn-5-ene-2,3-dicarboxylic anhydride [1]; 1,2,3,6-tetrahydro-3,6-methanophthalic anhydride [2]; (1α,2α,3β,6β)-1,2,3,6-tetrahydro-3,6-methanophthalic anhydride [3] CAS 129-64-6[1]826-62-0[
- ammonium dichromate CAS 7789-09-5
- amylase, α- CAS 9000-90-2
- amylases with the exception of those specified elsewhere in this Annex Index No 647-016-00-X
- benzene-1,2,4-tricarboxylic acid 1,2-anhydride; trimellitic anhydride CAS 552-30-7
- benzene-1,2:4,5-tetracarboxylic dianhydride; benzene-1,2:4,5-tetracarboxylic dianhydride; pyromellitic dianhydride CAS 89-32-7
- Bis(isocyanatomethyl)benzene; [m-XDI] CAS 3634-83-1
- bromelain, juice CAS 9001-00-7
- C,C'-azodi(formamide) CAS 123-77-3
- cellobiohydrolase, exo- CAS 37329-65-0
- cellulase CAS 9012-54-8
- cellulases with the exception of those specified elsewhere in this Annex Index No 647-004-00-4
- chromium trioxide CAS 1333-82-0
- chymotrypsin CAS 9004-07-3
- cis-1,2,3,6-tetrahydro-4-methylphthalic anhydride [1]; 1,2,3,6-tetrahydro-4-methylphthalic anhydride [2]; 1,2,3,6-tetrahydro-3-methylphthalic anhydride [3]; tetrahydromethylphthalic anhydride [4]; 1,2,3,6-tetrahydromethylphthalic anhydride [5]; tetrahydro-4-methylphthalic anhydride [6]; 2,3,5,6-tetrahydro-2-methylphthalic anhydride [7] CAS 1694-82-2[1]3425-89-
- cobalt CAS 7440-48-4
- cobalt carbonate CAS 513-79-1
- cobalt di(acetate) CAS 71-48-7
- cobalt dichloride CAS 7646-79-9
- cobalt dinitrate CAS 10141-05-6
- cobalt sulfate CAS 10124-43-3
- cyclohexane-1,2-dicarboxylic anhydride [1]; cis-cyclohexane-1,2-dicarboxylic anhydride [2]; trans-cyclohexane-1,2-dicarboxylic anhydride [3] CAS 85-42-7[1]13149-00-3
- diamminediisocyanatozinc Index No 030-005-00-3
- diammonium hexachloroplatinate CAS 16919-58-7
- diammonium nickel hexacyanoferrate CAS 74195-78-1
- diammonium peroxodisulphate; ammonium persulphate CAS 7727-54-0
- diammonium tetrachloroplatinate CAS 13820-41-2
- dipotassium hexachloroplatinate CAS 16921-30-5
- dipotassium peroxodisulphate; potassium persulphate CAS 7727-21-1
- dipotassium tetrachloroplatinate CAS 10025-99-7
- disodium hexachloroplatinate CAS 16923-58-3
- disodium tetrachloroplatinate CAS 10026-00-3
- ethyl 2-(isocyanatosulfonyl)benzoate CAS 77375-79-2
- ethylenediamine; 1,2-diaminoethane CAS 107-15-3
- ficin CAS 9001-33-6
- glucosidase, β- CAS 9001-22-3
- glutaraldehyde CAS 111-30-8
- hexachloroplatinates with the exception of those specified elsewhere in this Annex Index No 078-005-00-2
- hexachloroplatinic acid CAS 16941-12-1
- hexahydro-4-methylphthalic anhydride [1]; hexahydromethylphthalic anhydride [2]; hexahydro-1-methylphthalic anhydride [3]; hexahydro-3-methylphthalic anhydride [4] CAS 19438-60-9[1]25550-5
- hexamethylene-di-isocyanate CAS 822-06-0
- hexasodium 6,13-dichloro-3,10-bis((4-(2,5-disulfonatoanilino)-6-fluoro-1,3,5-triazin-2-ylamino)prop-3-ylamino)-5,12-dioxa-7,14-diazapentacene-4,11-disulfonate CAS 85153-92-0
- hydroxydisulfito platinum(II) acid CAS 61420-92-6
- laccase CAS 80498-15-3
- maleic anhydride CAS 108-31-6
- methyl 3-isocyanatosulfonyl-2-thiophene-carboxylate CAS 79277-18-2
- methyl isocyanate CAS 624-83-9
- methylene diphenyl diisocyanate CAS 101-68-8[1]2536-05-2
- nickel bis(4-cyclohexylbutyrate) CAS 3906-55-6
- nickel bis(sulfamidate);; nickel sulfamate CAS 13770-89-3
- nickel bis(tetrafluoroborate) CAS 14708-14-6
- nickel carbonate; basic nickel carbonate; carbonic acid, nickel (2+) salt [1]; carbonic acid, nickel salt [2]; [µ-[carbonato(2-)-O:O’]] dihydroxy trinickel [3]; [carbonato(2-)] tetrahydroxytrinickel [4] CAS 3333-67-3[1]16337-84
- nickel chromate CAS 14721-18-7
- nickel di(acetate) [1]; nickel acetate [2] CAS 373-02-4[1]14998-37-
- nickel dibenzoate CAS 553-71-9
- nickel dichlorate [1]; nickel dibromate [2]; ethyl hydrogen sulfate, nickel(II) salt [3] CAS 67952-43-6[1]14550-8
- nickel dichloride CAS 7718-54-9
- nickel dichromate CAS 15586-38-6
- nickel dicyanide CAS 557-19-7
- nickel difluoride [1]; nickel dibromide [2]; nickel diiodide [3]; nickel potassium fluoride [4] CAS 10028-18-9[1]13462-8
- nickel diformate [1]; formic acid, nickel salt [2]; formic acid, copper nickel salt [3] CAS 3349-06-2[1]15843-02
- nickel dihydroxide [1]; nickel hydroxide [2] CAS 12054-48-7[1]11113-7
- nickel dilactate CAS 16039-61-5
- nickel dinitrate [1]; nitric acid, nickel salt [2] CAS 13138-45-9[1]14216-7
- nickel diperchlorate; perchloric acid, nickel(II) salt CAS 13637-71-3
- nickel dipotassium bis(sulfate) [1]; diammonium nickel bis(sulfate) [2] CAS 13842-46-1[1]15699-1
- nickel dithiocyanate CAS 13689-92-4
- nickel hexafluorosilicate CAS 26043-11-8
- nickel hydrogen phosphate [1]; nickel bis(dihydrogen phosphate) [2]; trinickel bis(orthophosphate) [3]; dinickel diphosphate [4]; nickel bis(phosphinate) [5]; nickel phosphinate [6]; phosphoric acid, calcium nickel salt [7]; diphosphoric acid, nickel(II) salt [8] CAS 14332-34-4[1]18718-1
- nickel selenate CAS 15060-62-5
- nickel sulfate CAS 7786-81-4
- nickel(II) octanoate CAS 4995-91-9
- nickel(II) selenite CAS 10101-96-9
- nickel(II) stearate; nickel(II) octadecanoate CAS 2223-95-2
- nickel(II) sulfite [1]; nickel tellurium trioxide [2]; nickel tellurium tetraoxide [3]; molybdenum nickel hydroxide oxide phosphate [4] CAS 7757-95-1[1]15851-52
- nickel(II) trifluoroacetate [1]; nickel(II) propionate [2]; nickel bis(benzenesulfonate) [3]; nickel(II) hydrogen citrate [4]; citric acid, ammonium nickel salt [5]; citric acid, nickel salt [6]; nickel bis(2-ethylhexanoate) [7]; 2-ethylhexanoic acid, nickel salt [8]; dimethylhexanoic acid nickel salt [9]; nickel(II) isooctanoate [10]; nickel isooctanoate [11]; nickel bis(isononanoate) [12]; nickel(II) neononanoate [13]; nickel(II) isodecanoate [14]; nickel(II) neodecanoate [15]; neodecanoic acid, nickel salt [16]; nickel(II) neoundecanoate [17]; bis(.sc.d.sc.-gluconato-O1,O2)nickel [18]; nickel 3,5-bis(tert-butyl)-4-hydroxybenzoate (1:2) [19]; nickel(II) palmitate [20]; (2-ethylhexanoato-O)(isononanoato-O)nickel [21]; (isononanoato-O)(isooctanoato-O)nickel [22]; (isooctanoato-O)(neodecanoato-O)nickel [23]; (2-ethylhexanoato-O)(isodecanoato-O)nickel [24]; (2-ethylhexanoato-O)(neodecanoato-O)nickel [25]; (isodecanoato-O)(isooctanoato-O)nickel [26]; (isodecanoato-O)(isononanoato-O)nickel [27]; (isononanoato-O)(neodecanoato-O)nickel [28]; fatty acids, C6-19-branched, nickel salts [29]; fatty acids, C8-18 and C18-unsaturated, nickel salts [30]; 2,7-naphthalenedisulfonic acid, nickel(II) salt [31] CAS 16083-14-0[1]3349-08
- papain CAS 9001-73-4
- pepsin A CAS 9001-75-6
- phthalic anhydride CAS 85-44-9
- piperazine hydrochloride [1]; piperazine dihydrochloride [2]; piperazine phosphate [3] CAS 6094-40-2[1]142-64-3
- piperazine; [solid] CAS 110-85-0
- potassium dichromate CAS 7778-50-9
- proteases with the exception of those specified elsewhere in this Annex Index No 647-014-00-9
- proteinase, microbial neutral CAS 9068-59-1
- rennin CAS 9001-98-3
- S-(3-trimethoxysilyl)propyl 19-isocyanato-11-(6-isocyanatohexyl)-10,12-dioxo-2,9,11,13-tetraazanonadecanethioate CAS 85702-90-5
- slimes and sludges, copper electrolyte refining, decopperised CAS 94551-87-8
- slimes and sludges, copper electrolytic refining, decopperised, nickel sulfate CAS 92129-57-2
- sodium chromate CAS 7775-11-3
- sodium dichromate CAS 10588-01-9
- subtilisin CAS 9014-01-1
- succinic anhydride CAS 108-30-5
- tert-butyl (5S,6R,7R)-3-bromomethyl-5,8-dioxo-7-(2-(2-phenylacetamido)-5-thia-1-azabicyclo[4.2.0] oct-2-ene-2-carboxylate CAS 33610-13-8
- tetrachlorophthalic anhydride CAS 117-08-8
- tetrachloroplatinates with the exception of those specified elsewhere in this Annex Index No 078-001-00-0
- tetrasodium 4-amino-5-hydroxy-3,6-bis[[4-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]naphthalene-2,7-disulphonate [1]; Reaction products of 4-amino-5-hydroxynaphthalene-2,7-disulfonic acid, coupled twice with diazotized 2-[(4-aminophenyl)sulfonyl]ethyl hydrogen sulfate, sodium salts [2]; disodium 4-amino-5-hydroxy-3,6-bis{[4-(vinylsulfonyl) phenyl]diazenyl}naphthalene-2,7-disulfonate [3] CAS 17095-24-8[1]-[2]100
- tetrasodium 5-(4,6-dichloro-5-cyanopyrimidin-2-ylamino)-4-hydroxy-2,3-azodinaphthalene-1,2,5,7-disulphonate Index No 016-036-00-5
- toluene diisocyanate CAS 91-08-7[1]584-84-9[2
- tosylchloramide sodium CAS 127-65-1
- trypsin CAS 9002-07-7
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All hazard statements
The full list of H-codes with the jurisdiction switch lives on the hazard statements hub. For what to do about the hazard, see precautionary statements (P-codes).
Wording quoted from the regulation named above. Substance counts come from harmonised classifications in CLP Annex VI — the statements on a real product also depend on the supplier's own classification. Always check the supplier safety data sheet.