GES SpERCS

ESIG/ESVOC developed the Generic Exposure Scenario (GES) Titles and Use Mapping for REACH which have been prepared to support communication of uses through the solvents supply chain, including Specific Environmental Release Categories (SpERCS)

Background of SpERCS

The SpERCs  ( Specific Environmental Release Categories) have been developed by the industry to comply with the REACH requirements for ERC (Environmental Release Categories) but with realistic data and assumption for a particular use, instead of using the default conservative set of exposure conditions.

Environmental Release Categories (ERCs), which have been mapped to each GES title, describe representative use patterns. Each ERC is linked to default environmental release fractions that can be used to estimate release rates to the relevant environmental compartments.  These release fractions are, however, highly conservative (sometime violating mass balance, i.e., greater than 100% combined release over the air, water and soil compartments) and often require refinement for exposure assessment. More details on ERCs and use patterns can be found in ’Guidance on information requirements and chemical safety assessment, Chapters -R.12: Use descriptor system and R16: Environmental exposure estimation’.

To provide assessors with more realistic parameter values associated with operational conditions (e.g., site tonnage, release fractions, etc.) and risk management measures, Specific Environmental Release Categories (SPERCs) have been developed. While SPERC parameter values are generic, they have been derived from literature values and/or industry knowledge and are typically much less conservative than those values associated with ERCs.  A summary of ESIG/ESVOC relevant SPERCs may be found in the form of a look-up table on the worksheet entitled “SPERCS”.

ESIG/ESVOC SpERCS GUIDANCE

Assessors may use these values as the inputs that are necessary for exposure assessment tools. Each SPERC also has an associated factsheet which provides more details and references relating to the SPERC.  Some explanation of the values found in a SPERC and how they may be used follows:

• SPERC title – Identifier, mapped to GES title and ERC(s),that can be used for reference in REACH related documents, such as exposure scenarios, and is also the title of the corresponding SPERC fact sheet.
• TRA SPERC code – Informs user of which SPERC to select from drop down menu in ECETOC Targeted Risk Assessment Model.
• Maximum/Typical site tonnage – Site tonnage upon which local scale exposure assessments may be based.
• Number of emission days per year – Typical/default frequency of use. Used to derive annual tonnage from daily amount and vice versa.
• Release to air (%) before RMM – Estimate of proportion of substance released to air from process, compared to amount used. For some SPERCs, multiple values are given, based on vapour pressure. User needs to select relevant release fractions based on own substance properties.
• Efficiency of air emission control– Assumed onsite risk management measure removal efficiency for substance released from process to air.
• Release to air (%) - Remaining percentage of substance released to air compared to substance used, after removal by RMMs.
• Release to wastewater (%) -  Estimate of proportion of substance released to wastewater from process, compared to amount used. For some SPERCs, multiple values are given, based on water solubility. User needs to select relevant release fractions based on own substance properties. Note, wastewater RMM removal efficiencies and subsequent release fractions are typically substance- and site-specific, and therefore are not explicitly assumed in the SPERC.  A list of typical RMMs can be found in the SPERC Factsheet.
• Release to soil (%) -  Estimate of proportion of substance released to soil from process, compared to amount used. RMMs are not assumed.

Notes have been included in the spreadsheet to outline the approach used to derive SPERC values. A detailed account of each SPERC is provided in its Factsheet, which may be found here,

Use of SpERCS for Environmental Exposure Assessment

ESIG/ESVOC SPERCs have been entered in the ECETOC TRA (for assessing single substances) and CONCAWE Petrorisk (for assessing complex mixtures) models.  The Chesar tool will also be capable of utilizing pre-defined SPERC determinant files.  If an assessor would like to use a SPERC with any other tool (e.g., EUSES), it is their responsibility to override the default parameters by manual entry.

If an assessor runs an assessment tool with ERCs and the results suggest the need for reasonable risk management measures, it is not necessary to perform the same assessment using SPERCs.  It is at the Assessor’s discretion to choose to move from ERCs to SPERCs or start from the beginning using SPERCs.

It is important for the assessor to recognize and understand the boundary conditions/limitations of each SpERC.  Unfortunately, some of the following details are not obvious in ESIG/ESVOC SPERC look-up table (mentioned above) but are more explicit in the detailed SpERC factsheets which can be obtained for each GES in the GES Library.

SPECIFICS OF ESIG/ESVOC SpERCS

• The value for Emission Days is linked to M_SPERC and ECHA’s Chapter R-16 guidance on Environmental Exposure Assessment.  If M_SPERC is not applicable for an assessment (i.e., when Regional tonnage is less than M_SPERC), the assessor should confirm the appropriate value for Emission Days is included in the assessment
• There are two sets of Release Fractions to Air: i) ‘prior to RMMs’ and ii) ‘with RMMs’.  For the purpose of assessment the Release Fraction ‘with RMMs’ should be used, however, communication in the Exposure Scenario should be consistent with the assumptions made (i.e., release from the process is driven by the Release Fractions ‘prior to RMMs’ with the implementation of some RMM removal efficiency for air, that provides a final Release Fraction ‘with RMMs’.
• For many industrial use SPERCs, Release Fractions to Wastewater have been developed using the concept of substance solubility and wastewater volume generated during the process.  A critical assumption to this method is that no free product is releases in the effluent stream.  This is an important boundary condition that may or may not have implications on RMMs (i.e., whether or not oil-water separation is required onsite), and thus should be explicitly communicated in the Exposure Scenario.  Similarly, if this concept of substance solubility is not implemented in a SPERC, it is equally as important that an assessor not communicate that it has been.

It is a default assumption when using SPERCs that offsite/municipal wastewater treatment is applicable.  In the ECETOC TRA model, some pre-defined SPERCs also have built-in typical onsite removal efficiencies.  This is not the case for the pre-loaded ESIG/ESVOC SPERCs because we did not want to be prescriptive of what efficiencies are achievable onsite.  Consequently, if the assessment using an ESIG/ESVOC SPERC results in RCRs > 1, it is possible to refine the wastewater release fractions to simulate onsite RMM removal efficiencies.  This is achieved by first defining the required onsite removal efficiency:  RE_onsite = 1 – 1/RCR_{risk-determining}, where RCR_{risk-determining} is the highest RCR that is driving the risk.  The release fraction for wastewater is then reduced by the fraction of RE_onsite, which results in a new release fraction that is used to re-run the assessment.  In order to re-run the assessment, the assessor will no longer be able to select from the pre-defined dropdown list of SPERCs, but will instead have to enter the SPERC data manually into the OECD approach section of the tool and run a surrogate assessment.

It is important to note that if an assessment results in RCRs > 1, it may not always be due to wastewater releases (e.g., it may be an endpoint that is air release driven).  In either case, it will be the responsibility of the assessor to determine how to implement this refinement approach (i.e., reduction of air release fraction and/or wastewater release fractions).  Furthermore, for communication purposes, the assessor will have to explicitly indicate the process related release fractions, calculated onsite RMM removal efficiencies used, and the applicable offsite/municipal RMM removal efficiency.  To assist in this step, results from the TRA model can be summarized into a concise aggregated table using a ‘Transcription’ tool that has been developed and is available for use from ECETOC TRA.