At a glance
| Chemical family | Benzothiazole derivative — rubber vulcanization accelerator |
| CAS number | 149-30-4 |
| Classification | IARC Group 3 (not classifiable as to carcinogenicity to humans). EU CLP Skin Sens. 1A (H317 — strongest sensitisation category), Aquatic Acute 1, Aquatic Chronic 1 |
| Where you encounter it | Latex mattresses, rubber gloves, elastic waistbands, shoe soles, tires, rubber gaskets, some metalworking/coolant fluids, anti-corrosion additives |
| Sleep micro-environment relevance | One of the most common causes of rubber contact allergy. Present in natural latex mattresses, elastic components of bedding, and rubber parts of bed frames. The primary bedroom concern is allergic contact dermatitis |
Regulatory & certification status
| European Union | REACH SVHC candidate list (2021) — identified for very persistent, very bioaccumulative (vPvB) and skin-sensitising properties. CLP Skin Sens. 1A (H317). Not yet subject to Annex XIV authorisation requirement. Regulatory — European Union authority |
| United States | No specific consumer product restriction. Included in the ASTM D6600 standard patch test allergen series. OSHA does not set a specific occupational exposure limit. Regulatory |
| Canada | No specific restriction. Assessed under the Chemicals Management Plan. Regulatory |
| International | IARC Group 3 (not classifiable, evaluated 2018). American Contact Dermatitis Society Allergen of the Year 2008. Included in all major dermatological patch test series. Regulatory |
What it is
2-Mercaptobenzothiazole is a heterocyclic organosulfur compound used since the 1920s to accelerate the vulcanization (cross-linking) of rubber. It is one of the most widely used rubber chemicals in the world. MBT and its derivatives (MBTS, MBS, and others) are present in virtually all vulcanised rubber products. IARC evaluated MBT in 2018 and classified it as Group 3 — there was limited evidence of carcinogenicity in humans and inadequate evidence in animals. The primary health concern with MBT is allergic contact dermatitis: it is one of the most common rubber allergens, included in the standard patch test series used by dermatologists worldwide. The American Contact Dermatitis Society named MBT Allergen of the Year in 2008.
Where it shows up in bedding
MBT is present in the bedroom primarily through natural latex mattresses and latex mattress toppers, which contain vulcanised natural rubber latex. Elastic waistbands on pyjamas and underwear worn during sleep also contain MBT. Rubber components in bed frames (feet, bumpers, gaskets) are additional sources. For people with MBT allergy, prolonged overnight skin contact with latex mattresses can cause persistent dermatitis at contact sites. Mattress covers and encasements create a barrier that can reduce direct rubber-to-skin contact. Synthetic (non-latex) foam mattresses do not contain MBT.
Citations
- IARC (2018). Some Industrial Chemicals. MBT. IARC Monographs Vol. 115 (meeting in 2016; published 2018). Source Peer-reviewed
- Pontén, A. and Bruze, M. (2008). Contact Allergy to Rubber Chemicals. In: Kanerva's Occupational Dermatology. Source Peer-reviewed
- ECHA. 2-Mercaptobenzothiazole — Substance Information (SVHC candidate). Source Regulatory
Frequently asked questions
Can a latex mattress cause an allergic reaction from MBT?
Yes. If you are allergic to MBT (an estimated 2-4% of the population), prolonged skin contact with a natural latex mattress can trigger allergic contact dermatitis — redness, itching, and eczema at contact sites. This is a chemical allergy to the rubber accelerator, not a latex protein allergy (which is a separate condition). A dermatologist can confirm MBT allergy with patch testing. Using a mattress encasement or switching to synthetic foam can eliminate the exposure.
Is MBT the same as latex allergy?
No. MBT allergy is a delayed-type (Type IV) contact allergy to the chemical accelerator used in rubber vulcanization. Latex allergy is typically an immediate-type (Type I) IgE-mediated allergy to natural rubber latex proteins. They are different conditions with different mechanisms, though they can co-occur. MBT allergy causes eczema at contact sites; latex protein allergy can cause hives, swelling, and in severe cases anaphylaxis.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-07-08. If you find a factual error, contact us.