Denehurst Chemical Safety Ltd

This document is available as pdf - please request from info@denehurst.co.uk

 

 

Introduction to ES

The terms ‘Exposure Scenario’ (ES) and ‘Extended Safety Data Sheets’(e-SDS) are part of the new REACH terminology and are causing fear and dread among many chemical suppliers and users. However, the concepts and basic requirements are not difficult to understand and indeed, there are benefits in terms of providing appropriate risk management details.  So, in theory, this is rather good for chemical users.

 

The problem is that, in practice, most Exposure Scenarios have been over complicated and the early attempts in 2011 have not been very helpful to users; those writing these appear in many cases to be more interested in formatting and ‘box-ticking’ than to actual provide something of value to the recipient.

 

The key objective is that industry is not recommending uses for chemical products that lead to exposure greater than what have been estimated as acceptable.  It is essential that those writing and receiving extended Saftey Data Sheets can understand the content and act upon information provided.

 

What the legal text says

Where a Chemical Safety Report (CSR) is prepared as part of registration, the scenarios for exposure and estimates of exposure resulting from the proposed uses (reported as the ES) need to be communicated to downstream users as part of the SDS.  The SDS is therefore ‘extended’ to include the ES.  The SDS can be presented with a summary of the CSR findings, as it is accepted that the complex details in a full CSR are inappropriate.

 

A CSR is required for substances registered at levels above 10 t and every registrant will need to either present their own personalised CSR with their IUCLID dossier, or sign into (and agree with) a joint CSR prepared as part of joint submissions.  The REACH regulation has two headings for the scenarios of exposure (section 9 of the CSR) and these are ;

 

·        9.1 Exposure Scenario

·        9.2 Exposure Estimate

 

These are the only two mandated headings and although it makes sense to follow templates for the CSR or for the ES annex to the SDS, these are not legally binding.

 

The guidance is extensive and very helpful; however, the general theme is to use good science and to follow templates and use codes etc. where possible to allow relative harmonisation of documents. 

 

 

The ideal Exposure Scenario

The perfect ES (or indeed SDS) does not exist and if putting ten ‘experts’ in a room together, ten 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.

 

The science – risk characterisation ratio

The ratio between the level of exposure and the amount of exposure causing harm to no effect levels PEC and PNEC, or between workplace exposure and the DNEL, is ultimately used as an indicator of risk, allowing it to be quantitatively labelled.  If the PEC is greater than the PNEC (ie. ratio > 1 ), then it can be assumed that there is a risk of effects to the environment and likewise, if humans are exposed to concentrations greater than the DNEL, there may be a health risk. 

 

The scale of the risk can therefore be crudely measured by considering this ratio – a figure of < 1 is required to demonstrate that exposure is less than levels estimated to result in hazardous effects and therefore, the level of risk is ‘acceptable’.  However, if the RCR is > 1, some reduction of exposure is needed through use of Risk Management Measures (RMM); for example, an RCR of 1 to 10 could be reduced through use of local exhaust ventilation (LEV) that provides 90% reduction in exposure. 

 

The actual scientific value of a numerical value for risk may appear inappropriate (with the fundamental question of whether risk can be quantified numerically), but this does allow comparisons to be made between exposure scenarios or between different substances.  However, it must be remembered that both parts of the equation (hazard and exposure) are derived using defaults and large safety margins and this simple ratio does allow the degree of risk to be expressed easily.

 

The scheme describing the relationship between hazard and exposure data outlined in figure 1 demonstrates how the various documents required for REACH Registration and hazard communication fit together. 

 

The SDS remains the key communication tool and is supported by the other documents, if any of the sources of hazard or exposure data or the CSR itself are incomplete, the SDS will possibly fail to provide sufficient information.

 

The administrative activity of substance registration takes place within this framework, but without this fundamental review of hazard and exposure, it is not possible to know whether there is an acceptable level of risk in using a substance for a specific use.

 

Once the process of risk assessment broken down to the simple elements, it appears less complicated – however, the need to repeat this process for different substances being used in different scenarios or when considering different mixtures, suggests that there is considerable work to be done.

 

Hazard assessment

REACH requires that the hazard data are collated in the form of a Chemical Safety Assessment (CSA).  This needs to include hazard data relating to physico-chemical data, human health and environment and conclude with classification and choice of hazard statement to ensure correct labelling.  As part of this process, every substance will need a ‘derived no (or minimal) effect level’ (DNEL or DMEL) to be assigned.  This is described in more detail below.

 

It is impossible to isolate hazard from exposure at any stage of the process as high exposure may meant the that there is a greater need for a high level of certainty in the data; for low exposure uses, read across or modelling may suffice, but if high exposure, good quality testing may be necessary.  This is especially the case for environmental effects and if there is not exposure predicted for the soil, earthworm and higher plant testing may not be needed.  Exposure waivers are possible for registration (further guidance is available on this)

 

The types of hazard data considered necessary for the CSA are prescribed in the legal text of the REACH Regulation and depend on the volume of supply and on preliminary test data.  If it is not possible to conclude the classification and labelling requirements or it is not possible to determine safety limits for exposure to man or the environment, further assessment will need to be considered.

 

If new data are required, it is important to consult the official guidance.  This helps describe how to use published data, use models, conduct read-across and as a last resort, conduct new laboratory testing.  If new testing is to be performed, strategies are described to ensure that time and money, and especially animals, are not wasted.

 

The Derived No (Minimal) Effect Level or DN(M)EL

The DNEL, or for materials without a no effect level (eg certain carcinogens), a Derived Minimal Effect Level (DMEL), is calculated by taking the toxicity end points, including acute, sub-acute or chronic toxicity and applying ‘safety factors’ depending in the species, the duration of the study, the dose route etc.  The methods to make this calculation and the science that went into the process are too complex to discuss in this report, but it is described in Chapter R-8 of the technical guidance. 

 

As a rough rule, the tables in the guidance can be used (the key one is reproduced below), but it is possible to assign different factors if these are known form comparing real data with these assumptions.  In reality, only a few substances that have been examined in considerable detail will be possible to assess under more specific factors.  The most confusing part is the derivation of dermal and inhalation DN(M)ELs from oral data – the scientific validity is questionable and the units required for completion of IUCLID are difficult to relate to.

 

To compound these problems, the technical guidance on DNEL and DMEL is not that easy to follow and most of it is not going to be relevant to most registrants. For experts in the field, the source documents are worth reading, but for those not experts, the unfortunate advice is perhaps to find one.  However, the guidance does describe the concepts of hazard assessment for health, but some of the detail is unclear.  However, even if the DNEL does turn out to be a fairly random number, it does provide a system to compare the relative toxicity of substances that may have been tested by different methods.

 

The DNEL or DMEL is reported in the summary of toxicity in IUCLID and makes up part of the lead registration dossier and appears (or should appear) in the disseminated dossiers.  Many dossiers already submitted have poorly thought through DNELs or gaps with suggestions that they are not needed.  As ECHA slowly reviews the dossiers, the quality of the figures should improve and indeed, many registrants are making spontaneous updates to dossiers.  Once a substance is registered and the dossier published, the DNEL is effectively ‘official’

 

Those supplying hazardous substances (on their own, or in mixtures and above thresholds of concern) are expected to report the figures in the SDS.  The problem is that many readers of the SDS will not understand the DNEL and may confuse this with the exposure limits (eg WEL).  Unfortunately, there is likely to be considerable confusion as a result of publishing these rather meaningless numbers.

Table R. 8-6 Default assessment factors (reproduced from Chapter r-8 of technical guidance)

Assessment factor – accounting for differences in:

Default value systemic effects

Default value local effects

Interspecies

 

               - correction for differences in metabolic rate per body weight

                   - remaining differences

 

ASa, b

 And 2.5

1f

2.5g

Intraspecies

                        - worker

 

5

5

                        - general population

 

10c

10c

Exposure duration

                        - subacute to sub-chronic

 

3

3 h

                        - sub-chronic to chronic

 

2

2 h

                        - subacute to chronic

 

6

6 h

Dose-response

                        - issues related to reliability of the dose-response, incl. LOAEL/NAEL extrapolation and severity of effect

 

1d

1d

Quality of whole database

                        - issues related to completeness and consistency of the available data

                        - issues related to reliability of the alternative data

 

1d

1e

1d

1e

 

a AS = factor for allometric scaling which is ‘4’ for rat to human

b Caution should be taken when the starting point is an inhalation or diet study

c Not always covering for very young children; see text for deviations from default

d See text for deviations from default

e Special consideration needed on a case-by-case basis

f for effects on skin, eye and GI tract via simple destruction of membranes

g for effects on skin, eye and GI tract via local metabolism; for effects on respiratory tract

h for effects on respiratory tract.

 

To convert between different dose routes (oral to dermal, for example) needs special consideration and guidance on this is complicated with no clear recommendations. A case-by-case approach is recommended.

 

To make accurate estimates of no effect levels requires substantial data on a substance and substantial skill of the toxicologist; note that most registrations are being prepared with the minimum data requirements by those who perhaps do not fully understand the concepts.

 

Further guidance is available on DNEL estimates, but it is best left to experts who can use more than simple tables in the guidance to determine what are effectively the ‘safe’ levels for exposure. 

 

As a recipient of DNELs or DMELs in an SDS, first perform a sanity check.  Some ridiculously high figures have been published in the disseminated dossiers; for example, the Acetone dossiers (for some reason, two have been submitted) indicate a long term  inhalation DNEL of 1210 mg/m3. Common sense would suggest that this seems rather high and continued life time exposure at this level is not recommended.  

 

 PNEC

The Environmental equivalent of the DNEL is the PNEC – this is a more simple process as there is a standard safety factors applied according to the type of tests performed, such as toxicity to fish, Daphnia or algae.  For acute studies, the safety factor of 1000 is applied to the EC50 value; ie. a Daphnia EC50 following 48 hours exposure of 50 mg/l would lead to a PNEC of 0.05 mg/l.  Longer-term studies require a smaller safety factor, as indicated below and if there are multiple studies, for example more than one algal study, the results can be refined further.

 

If there is no effect at the limit of solubility, this limit needs to be used as a starting point.

 

 

Exposure

Registrants need to determine the points of exposure to workers, consumers and the environment as part of the registration.  For registration over 10 tonnes, this needs to be included in a formal Chemical Safety Report (CSR).

 

Although guidance for preparing the CSR and in particular, the Exposure Scenario (ES), is extremely complex, for most substances that are of low hazard, only generic descriptions and scenarios are necessary. 

 

The life-cycle of the substance needs to be considered by registrants (manufacture, packaging, formulation, final use etc), but for downstream users receiving extended-SDS, only part of the ES may actually apply to them.  For formulators, selling on mixtures containing the hazardous substances, there is a need to both understand the ES so that they can apply the RMM for their own activities, and then pass on relevant pasts of the ES when supplying mixtures to their own customers. 

 

To prepare an ES, it is therefore essential to know how the substance and any subsequent mixtures are used.  The best people to do this are those involved in practical health and safety or process engineering and not regulatory departments or external consultants.

 

To help industry, ECHA have provided a coding system (Chapter R-12 of technical guidance) and the PROC, PC and ERC codes for processes, product categories and environmental release are now fairly well known.  However, note that these codes are not indicated in any legal text and should not be seen as a hindrance for those writing ES.  They are there to help and to allow certain activities to be categorised to be put into models. 

 

For example PROC 5 covers blending and this will carry certain default levels of exposure to workers.  PROC 8 covers packaging and transfer of chemicals and sub-categories a and b relate to closed or open activities – closed being completely confined and automated and open describing typical pouring or pumping with non-dedicated equipment.  Guidance is good in Chapter R-12 with further advice in Chapters R-14, -15 and -16. 

 

Questions to customers asking for details of final use should be kept simple in the first instance and indeed, if the use of the substance is anticipated (eg. lubricant additive, pigment for paints etc) then it may be easier for the registrant to draft an exposure scenario and circulate to customers to confirm it is relevant and complete.

 

Complicated questions to customers have led to complicated answers (if any response at all) and some downstream users give a complete list of all process and use codes  have simply ticked every box and sent back to the supplier without thought.

 

The potential exposure to consumers needs to be described.  If only supplied as a substance or preparation for industrial use with no onward supply in products to the consumer, this must be stated.  The statement that supply is ‘limited for professional use’ is a good risk management measure; obviously if the customer wants to supply to the general public, then the risk assessment will need to be revised to take this into account.  This could be done by either the registrant or the customer; the key point is that everyone in the supply chain is satisfied that they can supply onwards within the scope of the registration and risk assessment.

 

 

Exposure to the environment

The Predicted Environmental Concentration (PEC) is the end-point of the environmental exposure assessment and can be calculated using data for the degradation or distribution of the substance in the environment (between water, air and solids) using physico-chemical and biodegradation data.  As well as the test data, other key factors include how the substance is manufactured, formulated or used and the dilution factors from use. 

 

The distribution of chemicals discharged to waste water treatment plants is described in the aptly named ‘SimpleTreat’ model.  This is a simplistic model that considers the volatility (Henry’s constant, H), the partition coefficient, adsorption coefficient and biodegradation.

 

Volatility                                Log H > 3        = Significant loss to air

Partition coefficient               Log Kow > 3   = Accumulation threat

Adsorption Coefficient          Log Koc > 3    = Adsorption to soil / sediment

Biodegradation                      > 60%              = Biodegradable

 

The model, presented in tabular form in the TGD or incorporated into the software of the risk assessment model EUSES (see below), compares each of these factors in determining the distribution of the substance in the environment.  A water soluble substance with Kow = 0, that is biodegradable, for example, is predicted to be 76% degraded with 24% lost to surface water.  But a non-biodegradable poorly water soluble material with a Log Kow of 4, may have 56% to water and 44% to sewage sludge.

 

Default figures are provided in the Technical Guidance Documents (TGD), describing estimated concentrations of waste in effluent, standard dilution factors, sizes of water treatment plants etc. These default values consider worse-case scenarios with, for example, 2% of material produced being lost to waste water, the position of the production unit in a small town with a small treatment works, and with final discharge going into a small river. However, where only limited sites are involved in production, formulation or use, location-specific factors can be used, such as the size of the waste treatment works, river flow rates etc. 

 

The conclusions of an environmental risk assessment based, on the ratio of predicted environmental concentration (PEC) and The requirements for risk assessment for substances reviewed under REACH follow the same concepts and the level of further control, or the need to submit more test data, may rest on the ratio between predicted exposure and the predicted no effect levels; ie. the Risk Characterisation Ratio. 

 

The conclusion of the Risk Assessment is the recommended Risk Management Measures – these describe what must be done to ensure Adequate Control.

 

Software

Software can be obtained for free to help in exposure assessment and three main tools are used by industry, with a fourth provided by ECHA that promises to be helpful, but sadly does not really live up to expectations.

 

EUSES - http://ihcp.jrc.ec.europa.eu/our_activities/health-env/risk_assessment_of_Biocides/euses/euses/?searchterm=None

 

ECETOC TRA - http://www.ecetoc.org/tra

 

ART - http://www.advancedreachtool.com/

 

CHESAR - http://chesar.echa.europa.eu/

 

EUSES is the original and perhaps still the best tool for environmental risk assessment, but is weak on workplace exposure.  The main advantage is that is it easy to view intermediary steps and change parameters and is easy to add data in a step-wise manner.  It is free to download (note original site for downloads closed recently and links in ECHA guidance have broken).

 

The free ECETOC Targeted Risk Assessment tool (TRA) is based on the same defaults and maths as EUSES and although intended to be easier to follow as a more simple process, it is indeed perhaps more difficult to use than EUSES.  The key advantage is that it recognises the use codes provided in REACH guidance and the defaults match those in the official guidance.  It is basically a glorified Microsoft Excel spreadsheet and some of the tabs provide helpful information on the defaults and exposure reduction expected by different controls.

 

The Advanced REACH Tool, ART, is, as it claims, an advanced tool to refine exposure considered of concern from the targeted risk assessment screening work. 

 

Chesar is a tool provided by ECHA and can plug in to IUCLID.  It is in theory  possible to run Chesar from data extracted from the IUCLID dossiers and can be a time saver.  However, the algorithms and modelling is no different to the more transparent models. 

 

The choice of model is often down to personal preference and experience.  TRA stands for ‘targeted risk assessment’ and this is a key point; the models are designed to help identify areas of concern and it is then up to the risk assessor to concentrate on these areas of highest concern.

 

The models must not be relied upon to give definitive answers; unfortunately, some consultants and regulatory agencies rely too heavily on what are a very clever, but limited, tools.  It is advised that any of these models are used to confirm you own manual assessment and if there is a major discrepancy in conclusions, reconsider your work.

 

The greatest danger in using any model is when this is done without the technical expertise to consider if the result is actually what you expect.  A quick back-of-envelope manual calculation may help models to be checked and one of the problems with the ECETOC TRA tool is that the ‘black-box’ approach in which numbers are entered and results presented. 

 

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.

 

Conclusions

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.

 

 

Denehurst provides training and advisory services for Exposure Scenario preparation and interpretation either as part of constructing chemical safety reports or in the contexts of the SDS

Links to other pages:

 

 

Exposure Scenario and the Extended Safety Data Sheet

 

Exposure Scenarios for Mixtures

The science of the Exposure Scenario and Exposure Estimate

 

 

Defaults

 

Back in the 1980s, a lot of work was done to quantify exposure to worker, consumers and the environment.  Work done then by the UK Health and Safety Executive (HSE) on worker exposure and the Dutch Government agencies on the environment and consumer has not changed a lot.  These included the EASE model for worker exposure, COSHH Essentials for risk identification and management in the workplace, ConsExpo for consumer exposure and various assumptions for the environment such as SimpleTreat found in EUSES and now CHESAR.

 

The cornerstone of this work was to set up standard defaults to help simplify the predictions for exposure and these in turn have been used to generate computer models (see below).  The defaults are assumptions that can be used for standardisation, but those making risk assessments and making exposure estimates can substitute the defaults for 'real' information and improve their exposure estimates. 

 

Typically, the approach is to prepare an assessment with these defaults and then fine-tune if the defaults are clearly wrong or if risk management is needed (exposure reduction) as the estimated exposure is too high for the estimated hazards.  The ratio between estimated exposure and the estimate no-effect levels (DNEL or PNEC) is the 'risk characterisation ratio' (RCR).  This is explained in more detail below.

 

 Some exposure estimate defaults are noted below:

  

Average human:

Weight 70 kg, surface area for each hand 480 cm2, breathing rate of 10 m3 per 8 hour shift

 

Average temperature:

Workplace 'ambient' is 20°C, models are set at 20°C > ambient = 40°C

Environment is 15°C

 

Daily discharge rates

2% of production for industrial manufacture or formulation, 100% for consumer uses

 

Default sewage treatment

Daily flow 2000 m3 based on 10 000 people at 200 litres per person per day. 

   

Default treatment efficiency

87% for readily biodegradable substance with low vapour pressure and low partition coefficient

   

Default river / sea

Daily flow 18 000 m3, leading to a dilution of 1 : 10 (final flow rate 20 000 m3).  Dilution factor 100 for marine discharge.

 

 

 

Software

 

To help with the calculations, models can be used.  However, for many classes of substance, the models can struggle; difficult substances include surface active substances, unstable substances, mixted isomers, UVCB, salts and metals.  In these cases, special care is needed, but sometimes it is hard to do better than a pencil, paper and lots of common sense.

 

Software can be obtained for free to help in exposure assessment

 

 

EUSES -

http://ihcp.jrc.ec.europa.eu/our_activities/health-env/risk_assessment_of_Biocides/euses/euses/?searchterm=None  

 

ECETOC TRA -

http://www.ecetoc.org/tra

 

ART -

http://www.advancedreachtool.com/

 

CHESAR -

http://chesar.echa.europa.eu/

 

EUSES is the original and perhaps still the best tool for environmental risk assessment, but is weak on workplace exposure. The main advantage is that is it easy to view intermediary steps and change parameters and is easy to add data in a step-wise manner. It is free to download (note original site for downloads closed recently and links in ECHA guidance have broken).

 

The free ECETOC Targeted Risk Assessment tool (TRA) is based on the same defaults and maths as EUSES and although intended to be easier to follow as a more simple process, it is indeed perhaps more difficult to use than EUSES. The key advantage is that it recognises the use codes provided in REACH guidance and the defaults match those in the official guidance. It is basically a glorified Microsoft Excel spreadsheet and some of the tabs provide helpful information on the defaults and exposure reduction expected by different controls.

 

The Advanced REACH Tool, ART, is, as it claims, an advanced tool to refine exposure considered of concern from the targeted risk assessment screening work.

 

Chesar is a tool provided by ECHA and can plug in to IUCLID. It is in theory possible to run Chesar from data extracted from the IUCLID dossiers and can be a time saver. However, the algorithms and modelling is no different to the more transparent models.

 

The choice of model is often down to personal preference and experience. TRA stands for ‘targeted risk assessment’ and this is a key point; the models are designed to help identify areas of concern and it is then up to the risk assessor to concentrate on these areas of highest concern.

 

The models must not be relied upon to give definitive answers; unfortunately, some consultants and regulatory agencies rely too heavily on what are a very clever, but limited, tools. It is advised that any of these models are used to confirm you own manual assessment and if there is a major discrepancy in conclusions, reconsider your work.

 

The greatest danger in using any model is when this is done without the technical expertise to consider if the result is actually what you expect. A quick back-of-envelope manual calculation may help models to be checked and one of the problems with the ECETOC TRA tool is that the ‘black-box’ approach in which numbers are entered and results presented.

CHCS Training on ES
 
http://www.chcs.org.uk/training/safety-data-sheet-training.htm#dates

 

 

REACHReady Workshop

   http://www.reachready.co.uk/services_training.php

 

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.

 

The format and content of ES will continue to evolve and hopefully will be seen as a useful addition to the communication tool for chemical suppliers and users.  Some software systems are now being offered, including ES-Pro from Safeware, that help in the selection of standard phrases, allowing 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.  Obviously, if during dilution to make the mixture, the hazard is reduced (eg solution of a corrosive substance) then an exposure scenario may not be needed other than advice that the concentration must be below a certain percentage.  However, if the substance is a sensitiser or STOT, dilution factors may not apply so readily.

 

Some regulatory agencies are now asking for exposure scenarios with mixtures and there is certainly a demand from some sectors of industry.

 

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 ES 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 report to ECHA (more information on the DU-CSR / reporting page)

 

(updated June 2015)

 

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.

 

Although not explicit in the legal texts of REACH and nothing yet is presented in official guidance, there is a demand from some regulatory agencies (and customers) for exposure scenarios to be provided with SDS for mixtures.

 

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.  For example, if the substance ES suggests maximum discharge rates of 2% of use, with waste water treatment handling a minimum 2000 m3 per day, then this can go in Section 13. 

 

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.