What are MDI, TDI, HDI, HMDI and IPDI?
MDI stands for Methylene diphenyl diisocyanate and TDI stands for Toluene diisocyanate. From a chemical point of view, they are aromatic diisocyanates and are considered organic compounds. Aliphatic diisocyanates are hexamethylene diisocyanate (HDI), methylene dicyclohexyl diisocyanate or hydrogenated MDI (HMDI) and isophorone diisocyanate (IPDI).

Where are they used?
Together with polyols, MDI and TDI are the essential building blocks for the manufacturing of polyurethane. They can be tailored to be either rigid or flexible, and are the materials of choice for a broad range of applications such as insulation in buildings and white goods; and adhesives, coatings, automotive parts, sportswear, etc. Aliphatic diisocyanates are light-resistant substances which are preferably reacted with polyester and polyether-polyols and used for coatings, sealants and elastomers where colour-stability is required.


Why did the EU adopt a Restriction on diisocyanates  under REACH?
The REACH Restriction on Diisocyanates was adopted due to the occupational sensitisation health effect they could pose to workers above a certain level of exposure. It is therefore a specific use restriction that is envisaged. Restrictions will target products containing more than 0.1% by wt monomeric diisocyanates.

When will the Restriction apply?
After the publication in the official EU Journal on 4 August 2020 and its entry into force on 24 August 2020, there will be a transition period of three years for companies placing diisocyanates on the market to give them adequate time to ensure compliance. This means the Restriction will apply from 24 August 2023. 

Can diisocyanates still be placed on the market in the EU and can I still legally use them?
Yes, diisocyanates remain available on the EU market but training is required for industrial and professional users.  The Restriction intends to improve the behaviour of employees at the workplace with the aim of reducing the risk of developing occupational asthma.

Which steps do I need to take under the Restriction?
Industrial or professional users will be permitted use of diisocyanates if they complete a training course ensuring the control of dermal and inhalation exposure to reduce the risk of asthma before 24 August 2023. ISOPA and ALIPA will keep stakeholders informed on the availability of the training materials and courses.

What will ISOPA and ALIPA do to support stakeholders?
Diisocyanate manufacturers have invested in the development of a comprehensive package of training materials, which we are preparing for rollout following the entry into force of the REACH Restriction. ISOPA and ALIPA have successfully launched safety initiatives in the past which have already helped to reduce the number of sensitisation cases significantly. Campaigns like “Walk The Talk” (2006) and “We care that you care” (2010) raised the awareness of workers dealing with hazardous substances and refined measures to avoid contact with diisocyanates and polyurethane hardeners via skin and breathing systems.


Are diisocyanates safe?
Like any substance, the use of diisocyanates is safe when chemicals are handled according to relevant risk management and safety measures. It is also important to stress that virtually no diisocyanates can be found in finished articles; hence, there is no consumer exposure. MDI and TDI do not migrate as they are only reactive chemicals.

Do MDI and TDI meet Substance of Very High Concern (SVHC) criteria?
Our industry firmly believes that MDI and TDI are not SVHC according to the criteria outlined under REACH, for the three following reasons:

  • The threshold for respiratory sensitisation is never met when risk management measures are applied correctly. Our industry is therefore convinced that the inclusion of diisocyanates as sensitisers under the SVHC process would not be justified or proportionate to the risk.
  • In case of exposure, the effects of MDI and TDI are reversible and not comparable to CMR (Carcinogenicity, Mutagenicity, Reproductive toxicity). When exposure ceases, the overwhelming majority of individuals with diisocyanate-related sensitisation show significant improvement or totally recovery.
  • In the last decade, we have observed a significant decrease in cases of diisocyanate-related sensitisation against a growing polyurethane market that doubled since 1995; confirming that new sensitisation cases can be eliminated by implementing safe exposure limits and appropriate controls.

What is sensitisation?
Sensitisation means that after a high level of exposure, a person could become allergic to the substance. If sensitised, each time the person is in contact again with the substance (even at very low concentrations) the person would have a strong allergic reaction with respiratory impacts (e.g. asthma). The majority of individuals with diisocyanates-related asthma show improvement over time or total recovery after exposure has ceased. Furthermore, it is important to highlight that the majority of diisocyanates uses are industrial or professional applications. Health complaints only occur if the person is in contact with the substance at high levels of exposure.

Are there any alternatives to diisocyanates?
Polyurethanes cannot be produced without aromatic or aliphatic diisocyanates. Therefore, there is no alternative for MDI, TDI, HDI, IPDI or H12MDI. To date, no other chemicals have been found to be able to replace their function in the production of polyurethane articles.

Are there alternatives to polyurethanes?
Polyurethanes provide outstanding benefits in many applications and contribute significantly to society´s sustainable development, e.g. through energy and resource efficiency. Alternative technologies are not available for all applications and alternative materials might not provide the same performance in terms of durability and efficiency.


What are the supply chains for these chemicals?
Diisocyanates and polyols are sold to downstream companies producing flexible and rigid polyurethane foams as well as elastomers, binders or coating materials. Further down the value chain, we find manufacturers of building insulation, white goods, automotive, furniture and bedding, footwear, coatings and adhesives, etc.

How many people does the industry employ?
According to a survey conducted in 2018 by an external party, the polyurethane industry involves more than 244,000 companies (most of which are SMEs), providing almost five million jobs in Europe:

  • 23 companies from the chemical industry are directly involved in the production of the main components for polyurethanes (polyols/ diisocyanates) creating creates jobs for 13,500 employees across Europe.
  • 350,000 employees directly contribute in terms of polyurethane production, including direct and downstream customers and their suppliers and subcontractors. Through its many applications, polyurethane is used by 4.7 million people throughout the EU in their work.

Which companies produce diisocyanates and polyols?
ISOPA represents the European manufacturers of aromatic diisocyanates and polyols, and its members are: Covestro, BorsodChem, Dow, BASF, Huntsman and Shell Chemicals. ALIPA is the European Aliphatic Isocyanates Producers Association. It was created by the major European producers BASF, Covestro, Evonik and Vencorex.



Under the EU's REACH Regulation, first and foremost, companies are obliged to collect information on the properties and the uses of the substances they manufacture or import at or above one tonne per year. This includes an assessment of their hazards and potential risks. Diisocyanates are registered under REACH in line with existing obligations. 


ECHA and EU Member States will then evaluate the information submitted by companies, as well as the quality of the registration dossiers and testing proposals, in order to clarify if a given substance constitutes a risk to human health or the environment.

REACH Evaluation led by Poland and Estonia

Both TDI and MDI have been added to the ECHA Community Rolling Action Plan (CoRAP).  TDI was evaluated in 2013 by the Polish Competent Authority which concluded that no regulatory action was needed.

MDI has been evaluated since 2013 by Estonia which concluded that no regulatory follow-up action was needed.  HDI was evaluated by Slovenia, which has also concluded that there was no need for further action.


The authorisation procedure aims to assure that the risks from Substances of Very High Concern (SVHC) are properly controlled, and that these substances are progressively replaced by suitable alternatives. SVHC substances are listed in the so-called ‘Candidate list’. The list includes Carcinogenic, Mutagenic, Reprotoxic (CMR) substances, Persistent Bio-accumulative Toxic (PBT) substances and substances of equivalent concern (endocrine disruptors, sensitisers, etc.).