Technical Report

TR 124 – Addendum to TR114 : Technical Basis for the TRA v3.1

TR124: Addendum to TR114 : Technical Basis for the TRA v3.1


In response to feedback received from users of the TRA, ECETOC has further improved the consumer portion of the model by the inclusion of the ability to account for infrequent uses of consumer products. The changes which have been developed in cooperation with ECHA are now found as version 3.1 of the TRA and are also to be found within version 2.3 of Chesar (

A detailed explanation of the rationale for the changes is contained in an Addendum to ECETOC Technical Report 114 (just published as ECETOC Technical Report No. 124) which provides further clarification of how ECETOC has applied ?transfer factors? in the TRA?s prediction of oral, dermal and inhalation exposures. These improvements now enable the information contained within developments such as the DUCC Specific Consumer Exposure Determinants ( to be suitably processed.

The update to version 3.1 was used as an occasion to include an updated SpERC list and improvements of the functionalities by offering the export and import of single substance datasets. Version 3.1 is available both as an integrated model and a standalone version for the consumer part, and can be found at the ECETOC TRA website together with updated user guides for these tools and ECETOC TRA Technical Reports.

The Addendum to ECETOC Technical Report 114 has been published as ECETOC Technical Report 124: Addendum to TR114: Technical Basis for the TRA v3.1.


ECETOC Technical Report 114 (ECETOC, 2012) Appendix F described the broad concept of the Specific Consumer Exposure Determinant (SCED). Following the release of version 3 of the TRA in 2012, various industry sectors have begun to develop SCEDs for their products. However, during the development of SCEDs, it has become apparent how conservative the current TRA algorithms are in their treatment of uses that are only carried out infrequently.

It must be remembered that version 3 adopts the algorithms contained in ChR15 of the REACH Technical Guidance (ECHA, 2010). But these assume that consumer uses of a substance are daily. This is clearly not the case with all consumer products.

At the same time, groups compiling SCEDs were not always clear on the meaning that ECETOC ascribes to the ?transfer factors? applied in the base algorithms.

This Addendum to Report TR114 sets out how infrequent uses of consumer products can now be evaluated in the TRA (as an enhancement contained in version 3.1) together with an extended clarification of the use of the term ?transfer factor?. It also provides further explanation of the basis behind the "Outdoor? and "Indoor? options which version 3.1 of the tool provides when conducting an inhalation exposure assessment for consumers.

This Addendum also clarifies the conditions under which the updated SpERCs should be incorporated when undertaking a TRA-based environmental exposure assessment.