CHCS  Chemical Hazards Communication Society  Promoting the awareness of chemical hazards & improvements in their identification & communication

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!)


The Deadline To Submit A Downstream User Notification (DUIN)
The deadline to submit a downstream user notification (DUIN) is almost here. CHCS members can read more on our News Briefings page[Posted on 26 October 2021]

The Carriage Of Dangerous Goods And Use Of Transportable Pressure Equipment Regulations Amendments Now Combined
The Dangerous Goods division of the Department for Transport (DfT) had been planning a consolidation of all the existing regulations on the carriage of dangerous goods, so that the UK industry need refer only to one Statutory Instrument. CHCS members can read more on our News Briefings page[Posted on 21 October 2021]

The Carriage Of Dangerous Goods And Use Of Transportable Pressure Equipment Regulations 2009 Amended
The Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009 has been amended by the Radiation Emergency and Consultation Regulations 2021. CHCS members can read more on our News Briefings page. [Posted on 21 October 2021]

ECHA - Safer Chemicals Recordings Available
On the 6th October 2021 The European Chemicals Agency (ECHA) held its safer Chemicals conference. CHCS members can read more on our News Briefings page[Posted on 20 October 2021]

CHCS' October 2021 Newsletter is now available, containing several important updates on the many recent changes to the regulation framework. See CHCS October 2021 Newsletter. 

GHS Revision 9 
Globally Harmonised System (GHS) Revision 9 has been published and is available online in both English and French. CHCS members can read more on our News Briefings page. [Posted on 20 September 2021]

UK Cosmetics Regulation
A new web page in the extensive set of Legislation pages on this website. For more details, see our Legislation web page[Posted on 1 September 2021]

MLA 340 And RID 06/2021 Counter-Signed By The United Kingdom
The United Kingdom has counter-signed Multilateral Agreement 340 and RID 06/2021 permitting sodium-ion batteries and sodium-ion cells using an organic electrolyte, or sodium-ion batteries and sodium-ion cells using an organic electrolyte contained in equipment or packed with equipment, to be carried without assignment of a UN number. CHCS members can read more on our News Briefings page. [Posted on 20 August 2021]

Publication Of The Draft 18th ATP To The CLP Regulation
The European Commission has published the draft 18th adaptation to technical progress (ATP) to Regulation (EC) 1272/2008 on the classification, labelling and packaging of substances and mixtures (the CLP Regulation). CHCS members can read more on our News Briefings page. [Posted on 17 August 2021]

Dangerous Emails Disguised As Coming From NPIS
Beware of potentially dangerous emails disguised as coming from the National Poisons Information Service - NPIS, which include attachments which the email encourages you to click. CHCS members can read more on our News Briefings page. [Posted on 29 July 2021]

SDS Will Be The Focus For Enforcement In 2023
At the most recent Enforcement Forum meeting it was agreed that safety data sheets (SDS) would be the main focus for 2023. CHCS members can read more on our News Briefings page. [Posted on 20 July 2021]

Government Updates Their Guidance On Poison Centres
The guidance page on poison centres has been updated with additional information on 'How to generate a UFI if you are a company based outside the EU or if you do not have a VAT number.' CHCS members can read more on our News Briefings page. [Posted on 29 June 2021]

Webinar: Substance Identity Testing Requirements for UK REACH
The presentation and recording from our webinar held on 22 June 2021 are now available to members linked from the Past Events page of our website. [Posted on 22 June 2021]

CHCS 2021 AGM & Annual Lectures
We are delighted to announce this year's AGM & Annual Lectures, taking place online over two afternoons: 22 & 23 November 2021. Details and timings to be confirmed, but registration now open. For more information, please see: CHCS 2021 AGM. [Posted on 21 June 2021]

Inception Impact Assessments (Roadmaps) For REACH & CLP - deadline 23:00 GMT, 1 June 2021
It is not too late to respond to the Inception Impact Assessments (Roadmaps) for the planned revisions to the REACH and CLP Regulations. CHCS members can read more on our News Briefings page. [Posted on 31 May 2021]

Poison Centre Practical Guide updated
The European Chemicals Agency (ECHA) have their practical guide relating to poison centre notifications. CHCS members can read more on our News Briefings page. [Posted on 20 May 2021]

ECHA Survey On Recycling Of Waste (deadline to respond: 27 April 2021)
The European Chemicals Agency is inviting stakeholders with ‘an interest in chemical recycling’ to respond to a short survey, which will feed into a larger study on chemical recycling of waste. CHCS members can read more on our News Briefings page. [Posted on 26 April 2021]

The Dangerous Goods Emergency Action Code List 2021
The new list has again been produced by the NCEC, in co-operation with the UK Home Office, and is published by TSO. CHCS members can read more on our News Briefings page. [Posted on 26 April 2021]

ECHA Updates Poison Centre Guidance
The European Chemicals Agency (ECHA) have updated their poison centres guidance document. Now on Version 4.0 the updated document gives information on some of the sector specific workability challenges. CHCS members can read more on our News Briefings page. [Posted on 6 April 2021]

Webinar: “Brexit - Do You Know What You Don't Yet Know?”
The presentations and recording from our webinar held on 1 April 2021 are now available to members linked from the Past Events page of our website. [Posted on 1 April 2021]

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.

To register for access to the video, please visit our video registration page: Endocrine Disruptors Video Registration.

[Posted on 1 July 2019]

CHCS News Summary
  • Update From HSE On UK REACH
    (5 March 2021)

  • Updates To ECHA’s Brexit Pages and Q&As
    (17 March 2021)

  • Update From HSE On UK REACH
    (5 March 2021)

  • The GB Mandatory Classification and Labelling (MCL) List
    (1 February 2021)

  • Update to Canada GHS (Aligned with 7th Edition) (26 January 2021)

  • UK Exit Of EU: Resources To Help As Transition Period Ends (11 December 2020)

  • End Of UK Transition Period – HSE Podcasts Series (9 December 2020)

  • Second Amendment Of Annex VIII of CLP (Poison Centres) Is Published (23 November 2020)

  • Poison Centre Portal Updated (30 October 2020)

      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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