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CHemical hazards Questions Forum 

CHCS runs an email-based discussion group, known as the Forum, for the mutual support of CHCS members and others with an interest in Chemical Hazard Communication.

With around two-thirds of the Forum subscribers being located in the EU, and around 80% of those in the UK, the Forum has had a natural bias towards European and UK issues. But with the introduction of GHS, and the magnitude of international trade – especially in mixtures – there are many product stewards outside the UK who consider it worthwhile to subscribe. At the last count, nearly a third of the subscribers were located outside of the UK in thirty-two different countries.

The CHCS email Forum generates significant interest, and is known to have a number of readers working for various regulatory bodies.

Subscribers have often been able to find help and guidance in areas where the regulatory framework is silent or unclear.

The Forum is free, is simple to join, and is open to anyone anywhere in the world who has a professional involvement in the subject of Hazardous Chemicals (Dangerous Goods) Communication.

The Forum is not a bulletin board, but a 'push' email system. Forum Subscribers submit their contributions by email to the Forum Operator: Questions, Responses, and News items. The only restriction in scope is that submissions should be relevant to Chemical Hazard Communication (CHC) matters.

The Forum Operator (ForOp), who also acts on behalf of CHCS as the primary moderator, then emails the content to each person on the subscription list. The subscription list is securely retained, and the addresses of other subscribers are not present in the emails received by the subscribers.

Examples of recent Questions from the Forum

Examples of recent Questions from the Forum with the various answers that reply directly and also draw out the different points involved are as follows:


Would anyone be able to advise the threshold limit levels for disclosing 2-Methyl imidazole (CASRN 693-98-1) in Section 3 of the SDS?


[Summary of responses]

Based on the REACH Registration dossier, and the proposed harmonised classification, the classification for the substance includes Repr 1B and Carc 2,

Both of these hazard categories result in a threshold for listing in the SDS as 0.1%, according to ECHA’s ‘Guidance on the compilation of safety data sheets’, p 47

That requirement assumes that the overall mixture is classified as hazardous according to CLP.

If the overall mixture is not classified according to CLP for any endpoint, and assuming it is not a gaseous mixture, then there is a general disclosure limit of 1% for hazardous ingredients in section 3 of the SDS: unless the substance happens to be PBT, vPvB or is listed on the Candidate list under “equivalent concern” basis (in which case 0.1% does apply).

With the imminent harmonised classification (14th ATP) of category 1B reprotoxicity, the mixture must be classified at 0.3% of 2-Methylimidazole; but if a mixture has less than 0.3% of this chemical and the mixture is not classified for any reason then legally it would not need to be disclosed. Reference REACH Annex II, 3.2.2


Does any quantity of broken package / spill of UN transport classified material need to be notified in every EU country (I have been told that it does in Finland)?

If so, is there a list of the authorities that coordinate this?


The incident reporting requirements are clearly defined in ADR

Depending on transport category, the reporting is required for spills greater than 50kg/50L (for Cat 0 or Cat 1) up to 1000kg/1000L (for Cat 4).

For trans-border transport ADR applies. But for local transport, local legislation can be more stringent.


Can anyone please comment on why Texanol (R):

2,2,4-trimethyl-1,3–pentanediol monoisobutyrate

CAS RN 25265-77-4

- is classified as a Category 2 Reproductive Toxicant in the USA?

This material is not classified as a Reproductive Toxicant by the European Chemicals Agency (ECHA):


[Summary of responses]

Texanol(R) is a commercial product. The Manufacturer's SDS shows that it contains 0.8% of the di-isobutyrate ester (EC 229-934-9, CASRN 6846-50-0). The di-isobutyrate ester is classified (inter alia) as Repr Cat 2, H361d

In the US, different concentration limits are used for the classification of mixtures for reproductive toxicity, compared to the EU (and other jurisdictions). In North America, mixtures containing reproductive toxins of Cat 1A/1B/2 are classified for this effect at a concentration of 0.1%, compared to 0.3% for Cat 1A/1B and 3% for Cat 2 in the EU.

This difference arises from the GHS, where both sets of concentration limits are given with the option for jurisdictions to choose which to use.

In US (and Canada), they have chosen to implement the lower concentration limit as the classification threshold. In most other jurisdictions the higher concentration limits are used as the classification threshold, with a note added to the classification tables, requiring disclosure of the ingredient on the SDS where the substance is present at or above the lower concentration limit.

There are similar issues for sensitisers, carcinogens and STOTS.

Subscribing to the Questions Forum 

Anyone joining CHCS will be automatically subscribed to the Forum, and need take no further action. You can download the Forum's "Conditions" from this link: CHCS Email Forum Conditions.

A non-member of CHCS wishing to subscribe to the Forum should send an email with the Subject "Forum Join", to

Please do not include any questions or other Forum content in the message. It will be ignored.

In the message, please give your name as you usually write it. The forename(s) and surname which you give will be into our database and will be shown at the head of any contributions (questions, responses, news) from you that are published as Forum messages.

You will be sent a message requesting consent for CHCS to process your personal information. Without that consent we cannot send you the messages.

Once your consent has been recorded, you will be sent a confirmation message with details on how the Forum operates.

CHCS will record, store, and use for sending the Forum messages, the email address from which the “Forum Join” message was sent. Requests to subscribe a third party cannot be accepted.

Changes of your email address should be sent to and the same rules will apply. An address change request may be subjected to a confirmatory check. Only one address per subscriber may be active at a time. If any email address is reported as no longer valid, it may be automatically deleted. In that case you will need to subscribe again from your new address.

When you leave the Forum, please notify Your personal data will be deleted on receipt of that notification.

Please feel free to mention the Forum to others whom you feel may be interested. Membership of CHCS is a not a requirement for becoming a Forum subscriber.

We look forward to receiving your request to join our Forum.


  1. CHCS reserves the right to terminate the Forum at any time.

  2. Whilst CHCS in general and the operator of the Forum in particular will use their best endeavours to ensure the accuracy and legality of the information transmitted the Forum messages do not create any liability or responsibility in any way for CHCS and/or its officers and members.

  3. The name of the originating subscriber is shown at the start of each contribution. The name used will be that held in the Forum address book, which will be as set out in the request to join.

  4. The Forum is not a bulletin board. You can only see the messages if your email address is on the subscription list held by the Operator.

  5. The forum is run by a CHCS volunteer. No service guarantee can be assumed or is given.

For further information on CHCS or the Forum please contact the CHCS Office.

No Messages?

The Forum is not an automated bulletin-board, but is a manual email messaging system involving real human beings. Nonetheless the Forum does not take many breaks. Any break longer than around four days would usually be announced in advance. So if you have seen no messages for a week or more, a filter or other gatekeeper at your end may be blocking the messages.

If you are a Forum subscriber whose message flow has dried up, please email the Forum Operator at to check; but you will need to provide an alternative contact channel for the ForOp to use to respond. (Because otherwise the email reply to your enquiry will fall into the same pit as the Forum messages themselves!)


CHCS' November 2023 Newsletter is now available, containing several important updates on the many recent changes to the regulation framework. See CHCS November 2023 Newsletter. [Posted on 17 November 2023]

DEFRA Publishes a Policy Statement on the New UK REACH Alternative Transitional Registration Model
The Department for Health and Rural Affairs (DEFRA) has published an outline of the new approach to UK REACH registration, following the commitment from Government to explore options for an Alternative Transitional Registration model (ATRm). CHCS members can read more on our News Briefings page [Posted on 16 November 2023]

GB CLP Mandatory List is Updated for the First Time
The Great Britain Mandatory Classification list (GB MCL) has been updated with new and revised GB MCLs for 98 substances. CHCS members can read more on our News Briefings page [Posted on 23 October 2023]

European Union Proposal for a Regulation on the Safety of Toys Notified to the WTO-TBT Committee
The European Union (EU) has notified a proposal for a new Regulation on the Safety of Toys to the World Trade Organisation, Technical Barriers to Trade (WTO-TBT) Committee, repealing Directive 2009/48/EC. CHCS members can read more on our News Briefings page [Posted on 5 October 2023]

EU Public Consultations – Candidate List Substances of Very High Concern
Public consultations are open on proposals for six substances identified as Candidate List substances of very high concern (SVHC) for authorisation of use, under European Union (EU) REACH. CHCS members can read more on our News Briefings page [Posted on 3 October 2023]

Germany Withdraws Proposal to Restrict Endocrine-Disrupting Bisphenols
Germany has withdrawn its proposal for the restriction of substances with endocrine-disrupting properties, specifically targeting bisphenols and their salts. CHCS members can read more on our News Briefings page [Posted on 27 September 2023]

Public Consultation on the Product Safety Regulatory Framework
The Department of Business and Trade (DBT) and the Office for Product Safety and Standards (OPSS) have issued a public consultation seeking views on the planned approach to product safety to ensure that the regulatory framework is ‘fit for the future.’ CHCS members can read more on our News Briefings page [Posted on 26 September 2023]

The UK REACH service team in The Department for Environment Food and Rural Affairs (DEFRA), are looking for users of the service to complete a survey. CHCS members can read more on our News Briefings page [Posted on 20 September 2023]

DFT Publishes Post Implementation Review of CDG Regulations
The Department for Transport (DfT) have published the results of the Post Implementation Review of amendments to the Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009, as amended in 2011, 2019 and 2020. CHCS members can read more on our News Briefings page [Posted on 6 September 2023]

United Kingdom Notifies Mandatory Classification and Labelling of 26 Substances to the World Trade Organisation
A proposed update to the Great Britain (GB) mandatory classification and labelling of 26 substances has been notified to the World Trade Organisation, Technical Barriers to Trade Committee (WTO-TBT) by the United Kingdom. CHCS members can read more on our News Briefings page [Posted on 29 August 2023]

Model Regulations, 23rd Revised Edition
The United Nations Recommendations on the Transport of Dangerous Goods, Model Regulations, 23rd Revised edition is now available in English and French. CHCS members can read more on our News Briefings page [Posted on 29 August 2023]

IATA Publishes Significant Changes to the 64th Edition of the Dangerous Goods Regulations
The International Air Transport Association (IATA) have published the significant changes to the 64th edition of the Dangerous Goods Regulations (DGR). CHCS members can read more on our News Briefings page [Posted on 24 August 2023]

GHS Revision 10 Published
Globally Harmonised System (GHS) Revision 10 has been published and is available online in English and French. CHCS members can read more on our News Briefings page [Posted on 7 August 2023]

EU REACH: PFAS Restriction Proposals
The European Chemicals Agency (ECHA) Committee for Socio-economic Analysis (SEAC) has adopted a final Opinion on the restriction proposal submitted in January 2022, concerning the use of firefighting foams containing PFAS.  CHCS members can read more on our News Briefings page [Posted on 28 July 2023]

20th ATP to CLP Published
Commission Delegated Regulation (EU) 2023/1435 of 2 May 2023 amending Regulation (EC) No 1272/2008. CHCS members can read more on our News Briefings page [Posted on 25 July 2023]

19th ATP to CLP Published
Commission Delegated Regulation (EU) 2023/1434 of 25 April 2023 amending. CHCS members can read more on our News Briefings page [Posted on 21 July 2023]

NEW - Module 81 on the New CLP Hazard Classes for Experienced Classifiers
This new training module is designed to give delegates an understanding of the new CLP hazard classes. CHCS members can read more on our News Briefings page [Posted on 18 July 2023]

CHCS Webinar: Hot Takes on Firefighting Measures
CHCS have now published the slides and recording from the webinar. CHCS members can access these on the Past Events page of our website. [Posted on 14 July 2023]

NEW - Module 16 on CLP Classification Extended to Include the New CLP Hazard Classes
Module 16 which covers CLP classification criteria for all CLP hazard classes has been updated to include the new CLP hazard classes for endocrine disruptors, PBT & vPvB, PMT & vPvM. CHCS members can read more on our News Briefings page [Posted on 7 July 2023]

CHCS Autumn Training Dates Released
CHCS have now released the Autumn training course dates. For more information, please view the Training page of our website. [Posted on 3 July 2023]

ECHA is Developing a New Data Availability System
A new Data Availability System is being developed by the European Chemicals Agency, ECHA. The first version is expected to be publicly available by the end of 2023. CHCS members can read more on our News Briefings page [Posted on 2 June 2023]

Proposed New Regulation on Detergents and Surfactants
The European Commission has published a proposal for a regulation on detergents and surfactants, amending Regulation (EU) 2019/1020, and repealing Regulation (EC) No 648/2004. CHCS members can read more on our News Briefings page [Posted on 31 May 2023]

Annex VIII of CLP to be Revoked
Under the Schedule of retained EU law it has been announced that Annex VIII of the Annex VIII of Regulation (EC) No 1272/2008 on classification, labelling and packaging (CLP) will be revoked. CHCS members can read more on our News Briefings page. [Posted on 22 May 2023]

Endocrine Disruptors - 1st CHCS Video

We have produced our first video for members: "Endocrine Disruptors", which is available to members free-of-charge.

This introductory video explains the various components of the human endocrine system and how they interact, to help understand the mechanisms of endocrine disruptors on human systems.

The video is just over 10 minutes long.

For access to the video, please visit: Endocrine Disruptors Video.

[Posted on 1 July 2019]

CHCS News Summary
  • (20 April 2023) DfT Consultation on Temporarily Increasing the Permitted Weight of Road Tankers Carrying Diesel

  • (17 April 2023) The Control of Explosives Precursors and Poisons Regulations 2023

  • (13 April 2023)United Kingdom Signposts the World Trade Organisation, Technical Barriers to Trade Committee of the GB Mandatory Classification and Labelling List

  • (4 April 2023)2nd IATA Addendum to the 64th Edition of the DGR

  • NCEC and DfT Newsletter
    (8 March 2023)

  • 21st ATP to CLP Notified to the WTO-TBT Committee
    (7 March 2023)

  • Titanium Dioxide Appeal by France
    (20 February 2023)

  • UK Government Response to EU’s Proposal for New CLP Hazard Classes
    (13 February 2023)

  • Progress Update on New EU CLP Classes
    (19 December 2022)

  • IATA Addendum to the 64th Edition of the DGR
    (16 December 2022)

  • Publication of GB Mandatory Classification and Labelling (GB MCL) Technical Reports
    (12 December 2022)

  • Publication of GB Mandatory Classification and Labelling (GB MCL) Agency Opinions
    (9 December 2022)

  • Call For Evidence: Investigation Report on Polyvinyl Chloride and its Additives
    (7 December 2022)

            CHCS Members can read these News items, and older posts, on the CHCS News Briefings page.

            Next 3 CHCS Training Courses:

            For a full list of our CHCS Training Courses, please visit our Training page. 

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