TOLUENE SULFONIC ACID (p-toluenesulfonic acid)
See the summary at the top of this page. CosIng, Annex II of Regulation (EC) No 1223/2009 (prohibited substances), Consulted on 23 October 2026.
Official label name (INCIInternational name of cosmetic ingredients: the one printed on the pack. name, EU glossary of cosmetic ingredient names), No 28956
Who it concerns
What official classifications and rules say for each group. A classification describes the hazard of the pure substance, not the risk of a product that contains it, which depends on the dose and the exposure.
Prohibition or serious classificationThe text prohibits the substance for this use, or ranks it among the most serious hazards (known or presumed carcinogenic, mutagenic or reprotoxic, identified endocrine disruptor).Worth watchingThe text sets a condition or flags a hazard worth knowing: allergen, suspected effect, condition for children, hazard to the aquatic environment.For informationOfficial information with no condition on a finished product: warning to read, irritation of the pure substance.
Pregnancy and breastfeeding
No classification harmonised by the European Union covers reproduction, the unborn child or breastfeeding for this substance. This does not mean it has been judged to have no effect during pregnancy.
Babies and children
The Cosmetics Regulation sets no age-related condition for this ingredient.
Skin, eyes and allergies
For informationOfficial information with no condition on a finished product: warning to read, irritation of the pure substance.
For information Classified under the CLP Regulation: eye irritation, category 2 (Eye Irrit. 2); skin irritation, category 2 (Skin Irrit. 2). This classification describes the pure substance; in a finished product it is far more diluted.
Environment
No harmonised classification as hazardous to the aquatic environment, and no EU act identifies it as an endocrine disruptor for the environment.
Read on the label
The Cosmetics Regulation requires no warning to be printed for this ingredient.
Regulation (EC) No 1272/2008 (CLP), consolidated version, Annex VI table 3, retrieved 21 October 2026.
In plain words
What it is used for
Functions declared by manufacturers:
The functions and their explanations appear in the summary.
Functions declared in the CosIngThe European Commission's database of cosmetic ingredients. inventory. CosIng, inventory of cosmetic ingredients (INCI names, CAS, EC, functions), retrieved 21 October 2026.
CosIng, list of cosmetic functions, retrieved 30 October 2026; source text read on 30 October 2026.
What the rules say
No EU rule targets this ingredient specifically. It remains subject to the general rule: every product must undergo a safety assessment before it is sold (Article 10 of Regulation (EC) No 1223/2009), under the manufacturer's responsibility.
See the summary at the top of this page.
What we know about this ingredient
Uses
/USED AS REAGENT IN/ KIRSTEN MODIFICATION OF KLEBER METHOD (FOR LEMON OIL).
Catalyst in coatings, paint, polymer, and textile industries. Stabilizer for monomers and polymers, pharmaceutical intermediate, cleaning agents, plating additive.
Effect solubility of disperse dyes, initiator for catalytic polymerization of caprolactam, catalyst for dimerization of alpha- methylstyrene.
Manufacture of 4-formylbenzenesulfonic acid, p-sulfobenzoic acid, 2-chlorotoluene-4-sulfonic acid, and 4-(chloromethyl)phenylmethanesulfonic acid
Manufacture of dyes and oral antidiabetic drugs; conversion to sodium and ammonium salts for manufacture of hydrotropes.
PubChem : Hazardous Substances Data Bank (HSDB) · 2026-10-29 · Association of Official Analytical Chemists. Official Methods of Analysis. 10th ed. and supplements. Washington, DC: Association of Official Analytical Chemists, 1965. New editions through 13th ed. plus supplements, 1982., p. 13/317 19.088; Kuney, J.H., J.M. Mullican (eds.). Chemcyclopedia. Washington, DC: American Chemical Society, 1994., p. 115; Kirk-Othmer Encyclopedia of Chemical Technology. 3rd ed., Volumes 1-26. New York, NY: John Wiley and Sons, 1978-1984., p. V22 48-9; Gerhartz, W. (exec ed.). Ullmann's Encyclopedia of Industrial Chemistry. 5th ed.Vol A1: Deerfield Beach, FL: VCH Publishers, 1985 to Present., p. VA3 520; Kirk-Othmer Encyclopedia of Chemical Technology. 3rd ed., Volumes 1-26. New York, NY: John Wiley and Sons, 1978-1984., p. V22 60.
Consumer uses
Catalyst
Solvent
Surfactant (surface active agent)
Use classification
Cosmetics -> Surfactant; Hydrotrope
Industry uses
Catalyst
Intermediate
Monomers
Solvent
Surfactant (surface active agent)
No natural occurrence recorded in Wikidata (LOTUS database); this does not prove that the ingredient is synthetic.
Basis: one CosIng CAS, with no natural occurrence recorded in this database.
Wikidata: names of substances in six languages and taxa in which they occur (largely from the LOTUS database), retrieved 23 October 2026.
Manufacturing
BY ACTION OF CHLOROSULFONIC ACID ON TOLUENE AT A LOW TEMPERATURE.
CONVENIENT LAB PREPN. SEPARATION OF TOLUENE FROM PETROLEUM FRACTIONS CAN BE ACCOMPLISHED BY SULFONATION WITH SULFURIC ACID @ 60 °C.
PREPARED BY SULFONATION OF TOLUENE WITH 96-100% SULFURIC ACID; WHEN CARRIED OUT AT 75 °C COMPOSITION OF REACTION PRODUCT IS 75% PARA-, 19% ORTHO- AND 6% META-TOLUENESULFONIC ACID.
PubChem : Hazardous Substances Data Bank (HSDB) · 2026-10-29 · Hawley, G.G. The Condensed Chemical Dictionary. 9th ed. New York: Van Nostrand Reinhold Co., 1977., p. 869; Budavari, S. (ed.). The Merck Index - Encyclopedia of Chemicals, Drugs and Biologicals. Rahway, NJ: Merck and Co., Inc., 1989., p. 1501-2.
Appearance
MONOCLINIC LEAFLETS OR PRISMS
Toluene sulfonic acid, liquid, with more than 5% free sulfuric acid appears as colorless to black solid. Odorless or nearly odorless. (USCG, 1999)
Liquid; Dry Powder; Liquid; Dry Powder; CBI; Large Crystals
PubChem : Hazardous Substances Data Bank (HSDB) · 2026-10-29 · Budavari, S. (ed.). The Merck Index - Encyclopedia of Chemicals, Drugs and Biologicals. Rahway, NJ: Merck and Co., Inc., 1989., p. 1501-2.
PubChem : CAMEO Chemicals · 2026-10-29 · U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office..
PubChem : EPA Chemical Data Reporting (CDR) · 2026-10-29 · https://www.epa.gov/chemical-data-reporting.
Stability
Normally stable; unstable at high temperature and pressure.
Other names: acide paratoluènesulfonique (French), p-toluenesulfonic acid (English), p-Toluolsulfonsäure (German), Ácido p-toluenosulfónico (Spanish), acido p-toluensolfonico (Italian), Ácido p-toluenossulfônico (Portuguese).
Wikidata: names of substances in six languages and taxa in which they occur (largely from the LOTUS database), retrieved 23 October 2026.
Open Beauty Facts, export of cosmetic products, retrieved 23 October 2026.
Data “Open Beauty Facts and its contributors”, licensed under ODbL 1.0 (opendatacommons.org/licenses/odbl/1-0); derived table distributed under the same licence.
The text of the annexes
No specific rule of the EU Cosmetics Regulation names this ingredient: it is on none of its lists (prohibited, restricted, colorants, preservatives, UV filters). It may be used under the responsibility of the manufacturer, who must ensure the product is safe.
Search in Annexes II to VI. CosIng, Annex II of Regulation (EC) No 1223/2009 (prohibited substances), retrieved 23 October 2026, source updated 13 October 2026.
What has changed, and what will change
Dates of the texts that cover this ingredient. A text date may cover several substances: the details of each entry are below.
CLP classification “Eye Irrit. 2” applicable at the latest from this date (Regulation (EU) 2018/669)
Identity
- CosIng identifier
- 38634
- CAS (according to CosIng)
- 104-15-4
- EC (according to CosIng)
- 203-180-0
- Declared functions
- Surfactant: hydrotrope Surfactant: cleansing
- Wikidata
- Q285878
- ECHA InfoCard
- 100.002.891
- InChIKey
- JOXIMZWYDAKGHI-UHFFFAOYSA-N
CosIng inventory. CosIng, inventory of cosmetic ingredients (INCI names, CAS, EC, functions), retrieved 21 October 2026.
Wikidata, items with a CosIng identifier (P3073), retrieved 22 October 2026.
Wikidata, PubChem and ECHAEuropean Chemicals Agency. links are published only when verified: same CosIng identifier, a single item, matching CAS number.
Classified hazard (CLP Regulation)
The harmonised classification is the one set by the European Union for the whole Union. H codes refer to the hazard statements of Annex III of Regulation (EC) No 1272/2008.
p-toluenesulphonic acid (containing a maximum of 5 % H2SO4)
Neither carcinogenic, mutagenic nor toxic for reproduction under the harmonised classification
- Hazard classes
- Eye irritation, category 2 (Eye Irrit. 2)
Specific target organ toxicity, single exposure, category 3 (STOT SE 3)
Skin irritation, category 2 (Skin Irrit. 2) - Hazard statements
- H319 H335 H315
Annex VI, entry 016-030-00-2, linked by CAS 104-15-4. Regulation (EC) No 1272/2008 (CLP), consolidated version, Annex VI table 3, retrieved 21 October 2026.
Entry introduced or replaced by Regulation (EU) 2018/669, applicable at the latest from 1 December 2019.
Elsewhere in the world
Information on other jurisdictions, with no effect on sale in France. What is covered, and what is not yet.
Comparison between countries
Most restrictive status in each country, and the maximum concentration cited. The details and the source of each rule follow.
| Country | Rule | Maximum concentration cited |
|---|---|---|
| European Union | No specific rule in the Cosmetics Regulation | not cited |
| United Kingdom | No specific rule in the Cosmetics Regulation | not cited |
| Switzerland | EU Regulation applies | not cited |
| United States (federal) | No federal rule recorded | not cited |
| Canada | No entry in the lists recorded | not cited |
| Japan | No entry in the lists recorded | not cited |
| South Korea | No entry in the lists recorded | not cited |
| China | Not on the prohibited lists recorded (lists of allowed substances are not recorded) | not cited |
| Australia | No entry in the lists recorded | not cited |
| ASEAN | No entry in the lists recorded | not cited |
| Taiwan | No entry in the lists recorded | not cited |
| Brazil | No entry in the lists recorded | not cited |
United Kingdom (Great Britain)
- No specific rule in the Cosmetics Regulation
Annexes II to VI in force. United Kingdom, Annexes II to VI of Regulation (EC) No 1223/2009 as retained and amended, retrieved 21 October 2026.
Contains public sector information licensed under the Open Government Licence v3.0.
Northern Ireland applies EU law.
Switzerland
Regulation (EC) No 1223/2009 applies in Switzerland (Article 54 of the Ordinance on Foodstuffs and Utility Articles).
Switzerland, FDHA Ordinance on Cosmetic Products (OCos, SR 817.023.31), consolidated version, retrieved 22 October 2026.
United States, federal rules
None of the integrated sections of the federal code (21 CFR 700.11 to 700.27 and 250.250) targets this name. The FDA does not publish a list of allowed ingredients.
United States, 21 CFR part 700 and section 250.250 (FDA rules on cosmetic ingredients), eCFR, retrieved 21 October 2026.
The eCFR is not an official legal edition of the Code of Federal Regulations.
Glossary: Commission Implementing Decision (EU) 2025/1175. Page updated on 23 October 2026.