TREXMO - TRanslation of EXposure MOdels

TREXMO (TRanslation of EXposure MOdels) is a peer-reviewed exposure assessment tool developed in collaboration with the Institut Universitaire Romand de Santé au Travail (IST) from Lausanne and the University of Geneva (see publication below).



The tool resides temporarily on the server of CHUV (Le Centre hospitalier universitaire vaudois). It will be transferred to the server of the Swiss State Secretariat for Economic Affairs at a later date.


The European Chemicals Agency (ECHA) recommends several models to assess occupational exposure to chemicals in the workplace, each differing in terms of complexity and conservatism. For many exposure situations, it is not clear which specific model should be used for the exposure assessment. In most situations, the user can choose between several suitable models. However, each model will probably result in different exposure estimates for the given exposure situation. Furthermore, no guidance is available to the user on how to interpret different models’ results, and little information is available about the levels of uncertainty associated with the exposure scenarios, parameters and the overall model. This complicates the estimation of exposure and hence the assessment of risk from hazardous substances in the workplace.

The TREXMO project offers a tool for reliable estimation of exposures in the workplace. For example, this tool can be used for establishing exposure scenarios as part of the chemical safety report and for the authorization process of substances of very high concern (SVHCs).

What is TREXMO?

  • TREXMO is a tool primarily developed to efficiently and reliably assess the wide variety of exposure situations using the available occupational exposure models. TREXMO integrates six commonly used occupational exposure models: ART v.1.5, Stoffenmanager® version 4.0 (Schinkel et al. 2010), ECETOC TRA v.3, MEASE v.1.02.01, EMKG-EXPO-TOOL and EASE v.2.0.
  • It includes a semi-automatic translation engine that is capable of efficiently translating a defined set of parameters from a given exposure situation in one of the models to the most appropriate corresponding parameters in the other exposure models. This method harmonizes the use of different models for the same exposure situation and reduces the uncertainties related to the use of these models. Ultimately, TREXMO should contribute to more reliable exposure estimations for exposure scenarios of concern.

Why is TREXMO needed?

  • It is often not clear which model to use and whether a 1st Tier (screening method) or 2nd Tier (in-depth analysis) approach is appropriate to estimate exposure for different exposure situations.
  • No guidance is available to interpret different model results and to handle the uncertainties associated with the exposure situation, parameters and models.
  • Models are not necessarily conservative. Various studies have shown that for many exposure situations the modeled exposure may be well above the corresponding measurement.
  • Several studies on between-user reliability showed extensive variability in users’ choices of model parameters leading to exposure estimates that ranged over several orders of magnitude for the same exposure situation.

What are the goals of the TREXMO project?

  1. to reduce the uncertain entry or selection of parameters in the six models.
  2. to reduce the time required for running several models for a given ES
  3. to benefit from more reliable exposure estimates
  4. to improve the between-user reliability.
  5. to encourage the use of TREXMO to establish exposure scenarios, e.g. for the chemical safety reports or for the authorization process of SVHCs.


The TREXMO project was funded by the Swiss State Secretariat for Economic Affairs (SECO) and the Swiss Centre for Applied Human Toxicology (SCAHT).

Legal Conditions

The TREXMO tool can be downloaded and used free of charge from the website of the Swiss Federal Administration. The following legal conditions of the Swiss Federal Administration apply:
Terms and conditions of the Swiss confederation

IT requirements

Only one of the following web browsers are needed: Google Chrome (45+), Safari (6+), Mozilla Firefox (38+) or Internet Explorer (10+).


We would like to thank the European Chemicals Agency (ECHA), the Agency Federal Institute for Occupational Safety and Health (BAuA, Germany), The National Institute for Occupational Safety and Health (NIOSH, US), the Environmental Protection Agency (EPA, US), the French Institute for Research and Security (INRS, France), The Institute of Occupational Medicine (IOM, Scotland), Korea Institute of Science and Technology (KIST, South Korea) and the Technical University of Ostrava (VSB, Tschechien) for technical discussions and advice on the development of the TREXMO Tool.


Contact TREXMO-Tool


Last modification 05.12.2022

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