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 comprising CHCS members who are themselves mostly UK based, the Forum has had a natural bias towards UK and European 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 30% of the subscribers were located outside of the UK in thirty-four 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 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.

On receipt of a Forum message, subscribers can:

  • discard it, as being of no interest
  • note it, and retain it for information
  • answer, completely or partially, a question that has been posed
  • submit a relevant comment on any item
  • forward the message to anyone else

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:


If I am supplying a product to the public and a tactile warning device is required, do I need to put this on:

      • the display box the product is displayed in, or;
      • the bottle inside the box. or;
      • both?


The TWD goes on the immediate receptacle - ie the bottle.

The CLP Regulation is not clear, although CHIP is. Nor is the ECHA Guidance on CLP labelling and Packaging.

However the Standard EN ISO 11683 clarifies this point.


We resell a mixture, one component of which is a corrosive category 1A that is 9% of the mixture. However, the supplier says that overall the mixture is non-hazardous. At that relatively low concentration, will the mixture have corrosive properties, or will it be diluted by the 91% which is non-hazardous?


[Summary of responses]

This is possible, but you are correct to be concerned. If you are using a calculation method for the mixture you describe, and you apply the generic threshold limits shown in CLP Table 3.2.3, the mixture would be corrosive to the skin at ≥5% and, would be a Cat 1 eye irritant at ≥3%, and hence the mixture would be hazardous.

However there may be reactions that occur in mixing with the other components, which reduce the corrosivity. Or the supplier may have had the mixture tested for corrosivity.

For your own protection you should ask the supplier to explain the basis for their claim that it is not corrosive to tissues, and if possible to supply evidence to back that explanation.

(One respondent reported exactly that experience: where a supplier had test results to back the non-hazardous classification)

You should also ask about metal corrosion effects since those apply to classification both for supply and for transport. It is possible that mixtures are classified as non-hazardous for supply in respect of their corrosivity to tissues, but classified as corrosive to metals. The latter can be the case at very low concentrations of the corrosive constituent.


A substance is classified as Aquatic Chronic 4 with H413 (May cause long lasting harmful effects to aquatic life). It is being shipped in 24,000 litre ISO Tank Containers.

The substance is not classed as Dangerous for Transport and thus the Tank Container needs no Placard nor Mark.

Does the Tank Container need a CLP label? There are derogations for small quantities, but I cannot find anything for this size.


[Summary of responses]

If the Tank Container is left with the purchaser and the substance/mixture is dispensed from it, that Tank Container is a package and needs to be labelled according to the provisions in CLP.

If the Tank Container is discharged into the purchaser's own storage, then the Tank Container does not need to be labelled, and different Regulations apply to the purchaser's storage.

This specific topic is covered by CLP FAQ Number 249 here.

NOTE: CHCS Members have access to an acronym listing available in the Member's Only area of this web site.

Subscribing to the Questions Forum

Those joining CHCS for the first time will be automatically subscribed to the Forum within a few weeks of their joining the Society. However, if they wish, new members of CHCS can subscribe to the Forum, as described below, at any time before that.

For those rejoining the Society after a break or lapse, the position will depend on how long the non-membership gap was. But if you are not sent a message to say that you have been automatically added to the subscriber list, you can always subscribe the Forum by following the instruction in the next paragraph.

To subscribe to the Forum simply 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, you should show the following:

  • your name as you usually write it. That is what will will be shown at the head of any contributions (questions, responses, news) from you that are published;
  • some alternative contact data such as your address, and/or your telephone/fax contact details;
  • if you are a current member of CHCS.

The contact information will only be used if there are problems with emails between you and the Forum. Your contact information will be retained by the Forum Operator only, and will not be passed to any third party outside CHCS, even if you request us to do so. Data relating to CHCS Members (only) may be shared within CHCS and then only on the specific request of the Forum subscriber concerned.

You will be sent a message confirming your subscription to the Forum with full details on how the Forum operates.

"Join" messages are only accepted from the address to be used for the outgoing messages; requests to subscribe a third party will be ignored. Advance notice of change of email address will usually be accepted, but may be subject to a confirmatory check. Due to operating constraints, only one address per subscriber may be active at a time. If any email address is no longer valid, it will be automatically deleted. You will need to subscribe again, with a full set of data, from your new address.

When you leave the Forum, all of your data, and any messages with your address on, will be deleted no more than fourteen days later.

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 automatic, but is driven by wetware (real human beings). Nonetheless the Forum does not take many breaks. Any break longer than around five 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 is probably stopping them.

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!)


Links To Guidance & Legislation Recently Laid Before Parliament

Links to new Guidance and Regulation amendments.

CHCS Members can read more on the CHCS News Briefings page.

RPA seeks input from companies in chemicals supply chain to assess impacts of Brexit

The Department for Environment Food and Rural Affairs has commissioned RPA to assess the impacts of the UK’s exit from the EU and the consultancy is now seeking participation of companies in the chemicals supply chain to assist it with this analysis.

CHCS Members can read more on the CHCS News Briefings page.

Preparing for a potential ‘no-deal’ exit from the EU New information from BEIS on the steps businesses need to take to prepare for a potential ‘no-deal’ exit.

CHCS Members can read more on the CHCS News Briefings page.

News Briefings Summary
  • 12 December 2018
    Impacts Of Additional Occupational Exposure Limits (OELs) & Other New Measures Under The Carcinogens and Mutagens Directive (CMD)

  • 11 December 2018
    HSE Adds Additional No-Deal Brexit Guidance On REACH 

  • 11 December 2018
    Latest Consolidated Version Of CLP

  • 7 November 2018
    EU Withdrawal Stakeholders Meeting (held October 2018)

  • 11 October 2018
    13th ATP for CLP Published

  • 11 October 2018
    Regulating chemicals (REACH) if there’s no Brexit deal

  • 25 September 2018: Microplastics and the current situation

  • 4 September 208: IATA publishes significant changes to the 60th Edition of the Dangerous Goods Regulations

  • 26 July 2018: REACH or CLP regulatory measures proposed for persistent, mobile and toxic (PMT/vPvM) substances

  • 26 July 2018 - REACH or CLP regulatory measures proposed for persistent, mobile and toxic (PMT/vPvM) substances

  • 6 July 2018 - HSE provide a "Chemicals" EU Exit web page.

    CHCS Members can read more on the CHCS News Briefings page.

    26 July 2018 - CHCS Labelling Competition

    Have you overcome a tricky labelling problem? Are you labelling a small or awkwardly shaped package, printing on a difficult surface, or have overcome another problem?

    Are you proud of your label designs that make it easier for customers to read and understand your labels?

    CHCS Members can enter our new competition. For more details please visit: CHCS Labelling Competition.

    9  July 2018 - CHCS Needs Your Help!

    CHCS has a number of vacancies on our committees and are looking for volunteers to fill them. For more information please see: CHCS Vacancies.

    Next 3 CHCS Training Courses:

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


    • Other events are in preparation. Please visit again soon.


    CHCS Membership is open to any person with an interest in chemical hazard communications. You can join by completing the simple on-line form at Join CHCS. Membership is currently £85.00 (+ £17.00 VAT where applicable; a total of £102.00). 

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    • General, membership and events/training enquiries:, tel+ 44 (0) 333 210 2427 (option 1)

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    See full CHCS Contact Details.

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