Tutorial
Version alpha 1
20 January 2025
ExposureModel is an application designed for users to input data about the chemical products they use, details of their usage, how exposure is managed, and to calculate exposure predictions using leading statistical exposure models.
Currently, the application includes two major models: Advanced REACH Tool (ART) and ECETOC TRAv3. It also incorporates inter-model translations of input parameters as defined by the TREXMO (Translation of Exposure Models) tool for these models.
In 2025, the application will expand to include additional statistical exposure models, such as EMKG-EXPO-TOOL, MEASE, EASE, and various mathematical models. The TREXMO translation system will be extended to support these models as well.
The ultimate goal for 2025 is to explore the feasibility of integrating artificial intelligence (AI) into the application. If viable, AI will assist in establishing more accurate exposure scenarios by enhancing the reliability of both the entered exposure data and the calculated predictions. Achieving this will be more practical as the database grows with user-submitted data.
The application is intended for anyone who manufactures, imports or exports chemical products and must comply with a chemical regulations, such as REACH in the EU. ExposureModel also can be used by researchers or anyone else interested in predicting air concentrations of chemical products generated in occupational environment.
The application consists of the six following modules
Suppliers
Components
Substances
Workplaces
Exposure scenarios
Exposure assessment
This module is optional but highly recommended for effectively tracking the suppliers of substances under concern. To identify a supplier, providing their name and country is mandatory, while additional details like city or contact information are optional. While supplier data may currently seem unnecessary or of limited relevance, it will become increasingly valuable as the application grows (expected in 2025) and the number of substances entered expands. Collecting this information now will provide significant benefits in the long term.
Under the REACH framework, and according to ECHA (European Chemicals Agency), a substance is a chemical in its natural state or the result of a manufacturing process. As such, a substance may include one or more “main” constituents, additives and impurities. These consisting components are actually the chemical compounds in their pure form.
For each component, it is mandatory to enter the following information:
Name – e.g., Phenol
Molecular weight, MW in g/mol – e.g., 94 g/mol (this information is required when converting concentration calculated in ppm, as in ECETOC TRAv3, to mg/m3)
Once a component is identified by its name and MW, the page with component details includes two additional sections, i.e., physical-chemical properties and exposure limits. It is mandatory to specify the component’s physical state and, for liquids, vapor pressure or boiling temperature. Without these information provided, a given component cannot be used to define substance composition (see Substances). Also, it is highly recommended to provide the exposure limit concentration(s), if available. When performing the exposure assessment, the system will compare the predicted exposure with the specified occupational exposure limits. It is crucial to identify the components, if any, of a substance that are close to or exceed defined exposure limits for evaluated occupational activities.
Once a component is part of the composition of a substance (e.g., specified as its main constituent, additive or impurity, certain data, such as its vapor pressure, cannot be modified. The same component can be reused to define the composition of one or more substances.
Once one or more components is defined (see Components), it is time to define the first substance instance. To create a new substance, its name and “substance type” must be specified. Substance type corresponds to the list of substance type defined on the ECHA’s page (for more information click here). As for components, once the substance form is submitted, it is necessary to specify its physical-chemical properties and composition. For substances that are liquids, it is mandatory to specify either its vapor pressure or boiling point, while for solids, the dustiness category is mandatory. The vapor pressure and boiling point of a substance is expected to be calculated by taking into consideration the vapor pressure and/or boiling temperature, activity coefficients and concentrations of the individual components that are included in the substance. In the next version, the ExposureModel application will provide a function to calculate the substance’s vapor pressure by using the component’s parameters.
Please note that the dustiness categories are actually those defined for Advanced REACH Tool. To be listed in an exposure scenario form, a substance must include these mandatory information and at least one component in its composition.
To facilitate the process of chemical risk/exposure assessment and the data entry in the exposure models, the users define workplaces with their general ventilation information in a workplace dedicated module. As for components and substances, the users may thus reuse the same workplaces’ properties when specifying general ventilation conditions for different exposure scenarios.
An exposure scenario can be defined once the system contains at least one substance with sufficient information and at least one workplace. The term 'exposure scenario' refers to guidelines for using a substance in a way that ensures exposure levels remain below toxicological threshold limits, safeguarding worker health. The ExposureModel application is intended to help you build exposure scenarios for different substances used in variety of activities.
An exposure scenario may include one or more activity in which a substance is used during its life cycle (e.g., manufacturing). These activities, also known as contributing activities, define substances’ use maps and may refer to the exposure to worker, consumer or environment. Although, currently, the ExposureModel application is intended to support the worker’s exposure assessment, the users are recommended to build their exposure scenarios by providing the information on contributing activities affecting consumers and environment. By doing this, the users will have a better overview on the impact of the substances under concern and their different use cases.
When creating a new exposure scenario instance, the users must provide its name, which must be unique, and the substance that the given scenario covers. One substance may, however, be used to define more than one exposure scenario. For example, one exposure scenario may address use cases (i.e., different contributing activities) of a substance during its manufacturing, while another scenario may address its actual use for a specific purpose in industry.
After an exposure scenario is created, the user must define different contributing activities by clicking on the “Contributing activities” page. The contributing activities, as discussed, are used to list specific use situations for substance withing the same life cycle stage as well as the aspect that the exposure affects, e.g., workers, consumers or environment.
For each contributing activity defined within an exposure scenario that refers to the worker’s exposure, it is necessary to provide exposure information necessary for the exposure assessment. These include, the exposure duration, activity related descriptors (such as, for example, activity class, Process category (PROC), scale of use, pressure applied, transfer rate, etc), workplace at which the exposure occurs (see Workplaces), localized controls applied to reduce the exposure (e.g., local exhaust ventilation) and similar. These information must be supplied in the third, SWED, section of exposure scenarios. SWED is short for Sector-specific Worker Exposure Description. For more information click here. For each contributing activity defined in the second section of exposure scenario form, only one SWED can be defined.
The ExposureModel application provides two statistical exposure models to conduct exposure assessment. These art:
Advanced REACH Tool – ART – defined as a higher tier model within the context of REACH due to its higher complexity and sophisticated exposure results.
ECETOC TRAv3 – defined as lower tier model that should be used for rather screening purposes.
Although the two models operate at different tier levels, the authors of this application recommend using both to evaluate the exposure of a single scenario. Each model is based on limited exposure data and behaves differently under varying conditions. For example, one model may be better suited for substances with lower vapor pressure, while the other is more reliable for substances with higher vapor pressures.
To create an exposure assessment, users can navigate to the home page or select the 'Exposure Assessment' module in the side menu. By clicking 'Create New,' users provide details about the exposure scenario to be assessed and choose one or both models to calculate exposure concentrations. The application automatically imports information about the substance, its components, contributing activities, and SWEDs, generating input parameters for both the Advanced REACH Tool and ECETOC TRAv3 models.
The results are displayed in the 'Exposure Results' section, where exposure values are listed for each contributing activity and model. Exposure is calculated individually for each substance component, and the user can compare these values against the occupational exposure limits (OELs), if provided. When multiple OELs are defined for the same component, the lowest value is shown. Results exceeding the OEL are highlighted in red, while values within 10% below the OEL are marked in orange for easy identification.
Users can view the list of exposure inputs for both models per contributing activity by clicking on 'Exposure Inputs.' This redirects to a page showing the selected input categories for each model’s determinants. While users have the option to modify certain input parameters, doing so automatically recalculates the exposure based on the changes.
However, the authors discourage altering input parameters, as it may create discrepancies with the data entered for the exposure scenario. This functionality is provided primarily as a quick way to compare exposure outcomes under different conditions. It is worth noting that this feature is planned for revision in the near future.
Additionally, users can create multiple exposure assessment instances for a single scenario. This feature is particularly useful for recalculating exposure after making changes to the exposure scenario, allowing users to compare different outcomes under varying conditions. This functionality provides a comprehensive overview of how exposure values differ based on adjusted parameters.