Extended-SDS (e-SDS) and Exposure Scenarios

The Exposure Scenario and Extended-SDS

The intention of the Exposure Scenario is to provide additional information for the user.  The best way to think of it is as ‘directions for safe use’ aimed at specific users, with the body of the SDS providing general advice.  Those used to dealing with pesticides or biocidal products will already be familiar with explicit guidance to help the user; perhaps different advice to those spraying ornamental roses to those spraying edible fruit. 

Unfortunately, in the early days of describing the scenarios for exposure, there seems to be more interest in providing pages of repeating text that at best provided little new information for the user.  Fortunately, the quality of the ES does seem to be improving and there is common ground appearing in the use of templates.

However, the UK HSE still considers there is plenty of scope for improvement in the quality of detailed advice on safe use to recipients of chemicals.  The extended-SDS is not a form to fill in, but must be useful.  However, this needs balancing with the convenience of software systems, allowing standardisation and translation to respective languages around Europe. 

Most chemicals are supplied as mixtures and there is no (current) requirement to provide an ES with an SDS for a mixture; the only requirement is to pass on down the supply line the information from the substance ES that is relevant for the intended use of the mixture. 

Advice is to apply common sense and good science and to remember that the purpose of the ES is to help the recipient. 

For recipients, there is a need to consider the extended-SDS that is received and take action as needed.  If the uses are not covered in the supplier CSR / extended-SDS, then the user may need to submit a Downstream User (DU) report to ECHA.

Mixture Exposure Scenario

Most chemical products are for mixtures and creating suitable SDS or the relevant exposure scenarios for mixtures is proving to be a challenge.

The legal position is that the findings of the Chemical Safety Report (CSR) prepared to support the REACH registration at over 10 tonnes per annum need to be communicated down-stream to end users with SDS.  Obviously, if no SDS is needed (for example, a non-hazardous product with no components present at concentrations that contribute to the hazard), then there is no need to communicate the findings of the CSR.

For mixtures, there is a choice;

1.    The CSR(s) developed for the substance(s) in the mixture can be simply passed on to the recipient of the mixture

2.    The findings of the Substance Exposure Scenario(s) are incorporated into the SDS, detailed in Sections 7, 8 and 13.

3.    An Exposure Scenario is developed for the mixture

The decision may depend on the mixture and for any range of products, there may be different reasons to choose one option instead of another.

1          Passing on the substance ES

This is the legal minimum.  When a substance is registered (over 10 tonnes per annum) an Exposure Scenario is developed as part of the CSR.  This will (or at least, should) include all the registered uses proposed by the registrant and for each of these uses, the type of mixture (liquid, solid, dusty etc) and the maximum concentration present in the end product.

Assuming the registrant has covered the uses of the end product (eg water based solution at up to 20% actives for use in textile dyes), then this part of the CSR will cover the product being supplied as a 5% solution. It may be easy to simply extract the relevant pat of the CSR and include as an annex to the product SDS. 

This approach works well if simple solutions / dilutions and if the physical properties are valid.  However, life is not always this simple and if there are two or more hazardous components, or if the physical form is not covered in the substance CSR, then this may not be an appropriate way forward. 

Obviously, if the use of the product, or the type of mixture is not covered in the registrant’s CSR, the downstream user will need to prepare a DU CSR..

2          Incorporating into the SDS

In many cases, products are sold for a single use; emulsion paint for use by brush or roller, adhesive for use in the building industry and so on.  In these cases, it is possible to make a note of the findings of the CSR(s) for the substance(s) and ensure the scenarios of use are covered in the SDS.  Remember that guidance for Directive 91/155/EEC on SDS in 1991 made it clear that the end uses must be considered carefully when writing the SDS.  This advice is still valid.

Sections 7 (handling and storage), 8 (personal protection and exposure limits) and 13 (disposal) are where most of the information needs to be included.  

Details of the estimated exposure form these scenarios of use can go in Section 8 and findings of the CSR can go in Section 15.  This is not specified in official guidance and is therefore cause for confusion; however, as long as such details are clearly communicated, then the legal obligations are met.

If there is more than one main use of the product, or if the mixture is itself sold for making into other products, then this approach may not work.  In this case, it is necessary to perhaps consider putting all the details in an annex to the SDS; ie an ‘extended SDS’.

3          Creating mixture Exposure Scenarios.

Unless supplying simple solutions or single-use products, it is likely that the option preferred by customers or regulatory bodies is to see appendices to the product SDS that cover the scenarios of use and detailing the estimated exposure from that use. 

How these mixture ES are prepared and presented is not covered in any legal texts or official guidance; in many ways, this is good as it leaves options open to the supplier.  The main guiding principle is common sense and good communication skills.

If considering a mixture of two or more substances that are identified as hazardous in Section 3 of the SDS, the first tasks are to look at the physical form of the mixture and to consider which components are contributing to specific hazards. One substance may be a major inhalation hazard as a dust, but if the mixture is a liquid for dipping or immersion, then this risk from dust is minimal. 

However, some mixtures will have a substance hazardous by inhalation and a second component that is corrosive to skin and a third component dangerous for the environment.  In these cases, it may be necessary to determine which component is contributing to specific risks and consider each for these cases.  This is not necessarily easy and a case-by-case approach is needed.  Perhaps this is why there is no official guidance yet. 

The ideal Exposure Scenario

The perfect ES (or indeed SDS) does not exist and if putting five ‘experts’ in a room together, six different documents would be produced.  They would probably all be legally compliant and (hopefully) useful to the reader, but still different.  The guidance from ECHA almost encourages this by suggesting that there are different models and theories that can be used to help estimate exposure or to derive no effect levels and a method hailed by one expert would be dismissed by another.  And there would very likely be good defendable reasons for the opinions of both.

Either way, the best test to determine a ‘good’ ES is whether it is actually useful to the recipient. The ES needs to include details of exposure to workers, the general public and the environment that are specific to expected use patterns of the substance (on its own or in mixtures).  Generic scenarios can be used (eg. Lubricants, paints, chemical intermediates) and through use of defaults, they should be suitably comprehensive to cover generic locations.  In other cases, site-specific ES may be appropriate, especially for substances of concern.

It is accepted that suppliers cannot know every detail of use by their customer and likewise, customers, or Downstream Users (DU) may not want to divulge their specific uses to suppliers.  Therefore, it is possible for DUs to prepare their own ES.  Some suppliers will not cover specialist applications and customers will find that they are on their own and need to confirm that the scenarios leading to exposure to their workers or onward customers are within the estimated no-effect levels.

For details on the ‘Science of the ES’, details are provided in guidance on the CSR [link]

Exposure Scenario Templates

A suggested format for the CSR Exposure Scenario is given in Section 9 of the CSR template provided in guidance from ECHA.  The template is provided as a tool to help prepare the CSR and to help promote consistency among those preparing the ES and subsequent CSR and is based on headings provided in Annex I of the REACH Regulation.

The full template is several pages long (before adding the relevant information) and is designed to be sufficient to cover all possible exposure types in the case of substances causing concern.  In particular, it planning to supply an Annex XIV substance that needs Authorisation, this will need to be completed to a high level of detail.

The legal text of REACH effectively allows registrants to take this multi-page document and cut-and-paste into the back of an SDS and call it an extended SDS.  In the early days of e-SDS, this was done by many organisations resulting in SDS in excess of 100 pages and there was a degree of completion at meets as who could find the longest SDS to moan about. 

Fortunately, only a minority of organisations thought this was the right thing to do and the majority followed ECHA guidance by preparing shortened Exposure Scenarios typically 2 pages long.  As indicated earlier in this guide, the legal text only mandates two headings and as long as these two points are covered, and key information from the CSR is communicated, the ES is legally compliant.

The exposure scenario should be brief and easy to ready be the expected audience.  The tables and details indicated in the CSR template should perhaps be held on file as the justification for the ‘communication’ tool that the Exposure Scenario is intended to be.

One of the more common templates is provided as an Annex; this may itself evolve and improve over time.  There is a lot more work to do yet.

The biggest problem is that very few ES provided to date actually provide helpful or concise information to the user.  The user needs to have details on any use-specific risk management measures that can only be summarised in the generic body of the SDS.  Different use scenarios will need different controls and each customer may have different problems and the ES needs to provide this support.

The template is therefore less important than the content and if necessary, writers need to adapt their template to suit their customer’s likely needs.


It is impossible to separate the processes of reading and writing ES; those writing e-SDS need to understand the in-coming ES so that it can be re-presented to customers and those working in health and safety roles must understand what inputs are relevant to make sense of ES that they receive and need to act on.  In both cases, understanding workplace exposure is key and the best people to write the ES are those actually in the factory or point of use.  Leaving it to regulatory departments or consultants who have not visited the factory is not going to result in practical ES.

A good ES will describe uses in a way that the user can relate to and then provide practical advice, with a view to the skill level of the user, to reduce exposure to levels lower than levels that are estimated to cause an effect to workers, consumers or the environment.  This level of ‘safety’ is described as the risk characterisation ratio.

If selling a chemical product for any use, it is essential that the use it is promoted for does not lead to a level of exposure higher to the no effect levels and if exposure is likely to be too great, risk management measures need to be communicated.

The SDS is the essential communication tool to meet these objectives (see SDS page [link].