Deze video van het RIVM is een tutorial over hoe blootstelling via inhalatie wordt geschat met de software ConsExpo Web. De tutorial laat de verschillende elementen zien die van invloed zijn op blootstelling via inhalatie. De inhalatieblootstelling via vapours en via sprays worden in aparte video’s getoond.

VOICE-OVER: 'Welcome to the ConsExpo Web tutorials for using models to estimate consumer exposure by inhalation. In this introductory tutorial, you will learn the basics of ConsExpo Web’s inhalation exposure simulations, which are explained in four stages: the release of substances from consumer products to the air in a room, the dispersion of substances through the air, the inhalation of substances, and the absorption of inhaled substances into the human body.'

'Basics of inhalation exposure simulations.'

'All inhalation models included in ConsExpo Web consist of the same four stages. First, the substance is introduced into the air in a room when released from a consumer product. Next, the substance is dispersed through the air. Here, the concentration of the substance in the air can be simulated over different periods of time and under varying conditions, such as ventilation rate, room size, or the amount released. The concentration of the substance in the air is considered to be equal to the concentration of the substance in the air that is inhaled by the consumer. Once the substance is inhaled, it may be absorbed into the human body. While these four stages apply to all ConsExpo Web inhalation models, ConsExpo Web has separate inhalation models for the release of substances that evaporate from a liquid product, are sprayed into the room as droplets, or evaporate from solid materials.'

'Release from consumer products.'

'ConsExpo Web provides different evaporation modes to estimate the release of substances into a room depending on the product scenario. In cases where the evaluated substance evaporates from a liquid product [1], you should select the exposure to vapour mode for a simulation.'

'In cases where the consumer uses an aerosol spray and the evaluated substance is released into the air as sprayed droplets, you should select the exposure to spray mode.'

'Lastly, ConsExpo Web is able to model the evaporation of a substance from a product that consists of solid materials. Examples of cases where you should select the solid materials model are solid construction materials such as wood or limestone that are impregnated with substances that can evaporate over a prolonged period of time.'

'All three release modes in ConsExpo Web calculate the amount of a substance released over time. The ConsExpo Web user needs to select the release modes that is most suitable for the specific consumer exposure scenario.'

'ConsExpo Web has general input fields that are used to simulate the inhalation exposure event and are common to all three release modes. These general input fields will be explained in this introductory ConsExpo Web tutorial. The general input fields are in the: scenario description, for example the frequency at which the consumer is exposed; scenario setting, such as the weight fraction of the substance in the product; the parameters needed for ConsExpo Web to simulate the dispersion through the air, such as the ventilation rate and the room volume; and finally the inhalation rate of the consumer and the absorption of the substance upon inhalation.'

'Dispersion through the air in the room.'

'Room volume is an important parameter for calculating the concentration of the substance in the air. The concentration in the air is calculated by dividing the amount of substance present in the air by the volume of air in the room. Therefore, the concentration in the air is inversely proportional to the volume of the room.'

'Another important parameter required to calculate the concentration in the air is the ventilation rate of the room. The concentration of a substance in the air is inversely proportional to the ventilation rate. ConsExpo Web requires a ventilation rate expressed ‘per hour’. This refers to the number of air changes per hour in the room. One way to calculate the ventilation rate is to divide the volume of air leaving the room per hour by the room volume. For instance, if it takes two hours for a complete change of air in the room, the ventilation rate is 0.5 per hour.'

'Since room volume and ventilation rate are general input parameters of ConsExpo Web, you may consult the general fact sheet to obtain the appropriate value for your specific consumer exposure scenario. Here is an overview of the type of rooms described in the general fact sheet with their respective default room volumes and derived ventilation rates.'

'Here you see how a graph can be displayed that shows the concentration in the air over time calculated by ConsExpo Web in an inhalation exposure simulation. You can find graphs like this one on the ‘Graphs’ tab. We use it here to explain the output of ConsExpo Web regarding concentrations in the air. The mean event concentration refers to the mean concentration of the substance in the room over the entire duration of the exposure event. In this graph, the mean concentration over 100 minutes is 5.5 mg/m3, which is the same as the mean event concentration found on the ‘Results’ tab.'

'ConsExpo Web also calculates a peak concentration. This peak concentration refers to those 15 minutes over which the air concentration is the highest within the exposure duration. This peak concentration is therefore also known as the time-weighted average concentration for 15 minutes, or the ‘TWA 15 min’ for short.'

' ‘Mean concentration on day of exposure’ refers to the mean concentration in the air of the substance over the entire 24 hours of the day of product use. As such, the mean concentration on the day of exposure is actually the same as the mean event concentration multiplied by the usage frequency (per day) and divided by 24 hours.'

'The same principle applies to ‘Year average concentration’, which is the same as the mean event concentration multiplied by the usage frequency (per year) and divided by 365 days.'

'Inhalation.'

'The inhalation rate and exposure duration are general inputs that ConsExpo Web needs to calculate the amount of the substance inhaled by the consumer.'

'In an inhalation exposure scenario, the consumer breaths in the air. ConsExpo Web simulates the concentration of the substance in the inhaled air by treating it the same as the concentration in the room air. The respiratory tract of the consumer is then exposed to the evaluated substance.'

'ConsExpo Web has a button that users can click to calculate an inhalation rate as a function of a consumer’s body weight, as specified in the earlier assessment settings, and the intensity of the exercise performed by the consumer.'

'The default exercise types are sleep, rest, light and heavy exercise. ConsExpo Web users can select the level of exercise that is most appropriate for the consumer exposure scenario in the calculator settings menu.'

'The results that ConsExpo Web provides for the inhalation scenarios are expressed as ‘external event dose’ and ‘external event dose on day of exposure’. The external event dose refers to the amount of substance inhaled by the consumer during the exposure event, which is equal to the product of the mean event concentration, inhalation rate and exposure duration divided by the consumer’s body weight.'

'The external event dose on the day of exposure is equal to the external event dose multiplied by the usage frequency per day.'

'Absorption.'

'Absorption refers to the process by which a substance enters the human body as a result of exposure. In the inhalation exposure scenarios, this refers to the dose that is absorbed by the respiratory tract upon inhalation of a substance. In ConsExpo Web, the absorbed substance amount is estimated using a fraction that is inserted as a fixed value.'

'If, for example, the user enters a fraction of 50%, ConsExpo Web will calculate the exposure assuming that 50% of the inhaled substance amount is absorbed into the human body and the remaining 50% is exhaled.'

'Next, the internal event dose is derived by multiplying the external event dose by the absorption fraction.'

'Similarly, the internal year average dose is the external event dose multiplied by the absorption fraction and the product usage frequency per year.'

'In summary, this tutorial explained the basics of how ConsExpo Web simulates inhalation exposure.'

'Thank you for listening to the introductory tutorial on ConsExpo Web inhalation modelling. We would like to acknowledge our partners: Health Canada, Anses, BfR, FOPH, the Netherlands Food and Consumer Product Safety Authority and the Dutch Ministry of Health, Welfare and Sport.'

On-screen text: Interested in ConsExpo and its partnerships? ConsExpo Web: the online consumer exposure assessment tool. www.consexpo.nl, consexpo@rivm.nl, Consumer Exposure and ConsExpo on LinkedIn.
ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland) and Health Canada and the Netherlands Food and Consumer Product Safety Authority and the Ministry of Health, Welfare and Sport.

Deze video van het RIVM is een tutorial over hoe blootstelling via inhalatie wordt geschat met de software ConsExpo Web, gericht op vapours. Oftewel blootstelling door verdamping. De tutorial laat de verschillende modellen zien die gebruikt kunnen worden.

VOICE-OVER: 'Welcome to the tutorial for using ConsExpo Web’s vapour release modes to estimate the inhalation of vapours released in consumer exposure scenarios. The tutorial includes an introduction to the instantaneous release, constant rate and evaporation modes and content about the input fields that are specific to these modes. In this introduction, we briefly explain the vapour modes included in ConsExpo Web, so that you are able to select the mode that is appropriate for your specific consumer exposure scenario.'

'ConsExpo Web includes vapour exposure scenarios in which the consumer uses a liquid product from which volatile substances evaporate into the room. Examples of such products are paints, cleaning products and liquid air fresheners.'

'All of ConsExpo Web’s vapour modes require the user to enter a value for exposure duration, room volume, ventilation rate and inhalation rate, and provide the option to enter a value for absorption to assess internal inhalation exposure. This applies to all inhalation modes and is therefore explained in the introduction to the inhalation modes tutorial.'

'The instantaneous release mode is the simplest vapour mode included in ConsExpo Web. It simply assumes that all of the substance is released into the room at once. Note that the concentration in the air immediately reaches its peak, as the substance is released immediately. As such, the instantaneous release mode also delivers the highest simulated exposure dose. This mode is most suitable for cases for which limited data are available or when the user wants to obtain a conservative estimate of inhalation exposure.'

'The constant rate mode assumes that the substance is gradually released over time. The concentration in the air increases as the substance evaporates at a constant rate over time. The release stops once the substance is depleted – as in the case, for example, of a long-lasting air freshener – or when the emission source is removed, for example when a bucket of cleaning product is flushed down the drain or when a bottle is closed.'

'The evaporation mode is ConsExpo Web’s most complex vapour mode. It simulates the evaporation of a substance from a product or treated surface based on its vapour pressure, molecular weight and the properties of the liquid product matrix containing the substance. This mode is more precise than the instantaneous release and constant rate modes, but also requires a higher level of detail in the input fields.'

'We will now explain the inputs that are required specifically for the instantaneous release and constant rate release modes.'

'Both release modes require the user to enter a product amount, which refers to the amount of liquid product used in the consumer exposure scenario expressed as a unit of mass, such as grams or milligrams.'

'The constant rate release mode also requires the user to enter the emission duration. This duration refers to the time during which the substance is released into the room. In a consumer exposure scenario, this may be the time between the moment a product is applied to a surface and the moment it is wiped off that surface, the time between the moment a product is poured into a container and the moment it is flushed down the drain, or the time during which a container holding a liquid product is left opened. The emission duration is expressed as a unit of time, such as minutes, hours or days.'

'Both the instantaneous and the constant rate release modes provide the option to limit the air concentration to the saturated vapour pressure. When choosing this option, ConsExpo Web simulates a balance between the concentration of the substance in the air and the amount of the substance deposited onto the walls, floor or furniture, as displayed here in the animation of cleaning a floor with a cleaning product and a mop. In order to calculate this balance, ConsExpo Web requires the user to enter values for the vapour pressure and molecular weight of the substance as well as the temperature at which the product is applied. Usually, this application temperature is the room temperature, which is set to 20 degrees Celsius by default. Please note that the balance between the concentration of the substance in the air and the amount of the substance is maintained during the release of the substance from the product and throughout the reduction of the concentration in the air due to ventilation. The consequence of including the option to limit the air concentration to the saturated vapour pressure is that the peak of the concentration in the air is lower, but the reduced concentration may persist over a longer period of time.'

'The upcoming graphs display typical simulations of an instantaneous release, constant rate release and constant rate release with the saturated vapour pressure option selected. The concentration in the air at instantaneous release immediately reaches its peak and then declines due to ventilation. At constant rate release, the concentration in the air increases until a maximum is reached and then declines due to ventilation. When the saturated vapour pressure is provided as an input, the peak is reached is lower because the substance is also deposited onto the furniture, walls and floor. However, the concentration of the substance in the air remains stable for a longer period of time, because substance still evaporates from the furniture, walls and floor to maintaining the balance with the concentration in the air.'

'In this next part of the tutorial, we will introduce you to the evaporation mode, which is the most complex vapour mode included in ConsExpo Web.'

'This mode requires the user to provide input on the chemical properties of the evaluated substance, such as vapour pressure, molecular weight and whether the liquid product is made of ‘pure substance’, which means that the liquid consists of a single substance only. If, however, the substance is mixed into a liquid with other ingredients, the evaporation mode also requires input on the chemical properties of that mixture, such as the molecular weight matrix and whether the product is diluted before the consumer uses it. Liquid cleaning products, for example, are diluted in a bucket of water before they are used to clean surfaces.'

'For example, if a product consists of 100% ethanol, you can select the substance in pure form. A vapour pressure of 5,950 Pa and a molecular weight of 46 g/mol can be entered into the appropriate input fields. The ConsExpo Web evaporation mode is then able to simulate an evaporation rate based on these two chemical properties. Note that a value of 1 as fraction or 100% as percentage needs to be entered into the input field ‘Weight fraction substance’.'

'If, however, the evaluated substance is mixed into a liquid that contains other ingredients, ConsExpo Web needs more information to perform a simulation. The evaporation rate is derived from the partial vapour pressure of the substance within the product matrix, which is based on Raoult’s law. Raoult’s law states that the partial pressure of each component of an ideal mixture of liquids is equal to the vapour pressure of the pure component (liquid or solid) multiplied by its molecular fraction in the mixture. In other words, the partial vapour pressure of a substance in a liquid consumer product is estimated by multiplying the molecular fraction of the substance in the product by its vapour pressure. The molecular fraction is the amount of moles of the evaluated substance divided by the total amount of moles in the mixture. ConsExpo Web includes an input field called ‘Molecular weight matrix’ for simulations that are based on Raoult's law.'

'Here is a brief example to explain how to enter the appropriate value for the molecular weight matrix. The liquid product in the example is an ideal mixture that consists of 75% water, 15% methanol and 10% ethanol. Note that these are weight fractions. Ethanol is the substance to be evaluated. You need to obtain the molecular weights of the other ingredients and derive their respective amounts in mole per gram of liquid product, which you can calculate by dividing the weight fraction of the ingredient by its molecular weight.'

'The evaluated substance, in this example ethanol, is considered to be separate from the molecular matrix into which it is mixed. The information on ethanol is therefore crossed out. The molecular weight matrix is then calculated by dividing the number 1 by the sum of the amounts in mole per gram of product of the other ingredients. In this example, the molecular weight matrix is 21.6 gram/mol.'

'In practice, however, the entire composition of the liquid product is often unknown. In this example, the mixture consists of 70% water and 5% unknown ingredients. Despite this lack of data, you can still enter a value for the molecular weight matrix. The molecular weight matrix is then calculated using the molecular weights and mass fractions of the ingredients that ARE known. In this example, the molecular weight matrix is AT MOST 22.9 g/mol, as the inclusion of any other ingredient would lower the calculated value. ConsExpo Web’s simulated concentrations in the air increase when the molecular weight matrix is increased, so an estimate of the molecular weight matrix value with missing ingredients is a conservative approach.'

'Note that the molecular weight matrix does not include the evaluated substance itself. If, for example, the substance of methanol is evaluated instead of ethanol, the value of the molecular weight matrix based on other ingredients would be 24.4 g/mol.'

'In some scenarios, the product is diluted before use. Common examples are surface cleaning products diluted in a bucket of water before the consumer starts to treat surfaces, or a dishwashing detergent that is diluted in the hot water of a sink or bowl. In these cases, the evaporation rate is affected by the dilution, as the product containing the evaluated substance is a mixture as well. Here, we briefly explain how to enter the appropriate value for the number of times the product is diluted.'

'The number of times a product is diluted is derived by dividing the weight of the product used by the weight of the overall mixture. Products are most often diluted in water, which has a density of 1 milligram per millilitre.
If 10 g of product is diluted in 200 ml of water, the resulting overall mixture weighs 210 g. The number of times the product is diluted is the sum of the product and solvent amount, in this case 200 g plus 10 g, divided by the product amount, in this case 10 g. In this example, the product is diluted 21 times.'

'Evaporation is determined by the difference between the vapour pressure in the air and the saturated vapour pressure of the substance in the product. The rate of evaporation is proportional to this pressure difference and depends on the surface area of the product and the mass transfer coefficient. This mass transfer coefficient is a measure of how slowly or quickly the evaporated substance is transferred from the product surface into the air.'

'The mass transfer coefficient accounts for the fact that emission from a product is limited due to the presence of a stagnant layer of air over the product surface, through which the substance must diffuse to reach the air in the room. The mass transfer coefficient depends on a number of factors, such as the substance’s molecular weight, the air flow over the product, and the surface roughness of the product.'

'The most recent ConsExpo Web fact sheets suggest a default value for the mass transfer coefficient of 10 meters per hour. Options to calculate a mass transfer coefficient using the Langmuir and Thibodeaux methods are mentioned in earlier fact sheets, but are considered less appropriate. The methods are still available in ConsExpo Web as legacy features, mainly for the purpose of re-evaluating of consumer exposure simulations performed in the past.'

'The evaporation mode gives the option to simulate the release of a vapour from a ‘constant release area’, meaning that the area from which the substance evaporates does not change over time. Examples of constant release areas include an opened bottle, a carpet with stains or kitchen sinks. Appropriate values for such release areas are presented in ConsExpo Web fact sheets.'

'The emission duration refers to the time during which the substance may evaporate from the release area. For example, a carpet stain treated with a cleaning product is left to soak before it is wiped clean. In that case, the emission duration refers to the soaking period. Other examples of emission duration include the time between the moment at which a product is mixed into a bucket and the moment the bucket is flushed down the drain or the time between the moment the lid of a paint bucket is removed and the moment it is replaced.'

'The evaporation mode also gives the option to simulate release from a release area that increases in size over time, or an ‘increasing release area’. Increasing release areas are relevant in scenarios in which the product is applied onto a surface that increases in size over time. ConsExpo Web then corrects for the fact that the release area is not as large at the beginning of the consumer exposure as at the end.'

'Typical examples of exposure scenarios that involve an increasing release area include painting a wall or mopping a floor with a cleaning product. The application duration refers to the time it takes for the consumer to apply the product onto such a surface area. For example, ConsExpo Web fact sheets indicate that it takes 20 minutes to treat a surface area of 22 m². The application duration is therefore 20 minutes.'

'Here you can see the effect of an increasing or constant release on the concentration in the air over time. In scenarios with an increasing release area, the concentration in the air gradually increases as more product is being applied onto the surface from which a substance evaporates . The concentration in the air still increases after the application duration ends. Here, the substance still evaporates from the release area while ventilation removes the substance released earlier from the air.'

'In the case of a constant release area, the concentration in the air increases until the moment emission stops and ventilation removes the remaining substance from the air.'

'In summary, we have used this tutorial to demonstrate how to select the appropriate vapour mode that fits your consumer exposure scenario and how to make sure to check the appropriate boxes and insert appropriate values into the input fields that are specific to the instantaneous release, constant rate or evaporation modes.'

'We hope that this tutorial has been helpful. In a next tutorial, we will tell you more about the evaporation mode. We would like to acknowledge all partners in the ConsExpo project: Health Canada, Anses, BfR, FOPH, the Netherlands Food and Consumer Product Safety Authority and the Dutch Ministry of Health, Welfare and Sport.'

On-screen text: ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland) and Health Canada and the Netherlands Food and Consumer Product Safety Authority and the Ministry of Health, Welfare and Sport.

Deze video van het RIVM is een tutorial over hoe blootstelling via inhalatie wordt geschat met de software ConsExpo Web, gericht op sprays. Oftewel blootstelling door verdamping. De tutorial laat de verschillende modellen zien die gebruikt kunnen worden.

VOICE-OVER: 'Welcome to one of ConsExpo Web’s online tutorials. This video will give you insight into the exposure estimated by the spray models available in ConsExpo Web.'

'Many consumer products are applied by spraying, and there is an increasing trend of spray applications. Examples are air fresheners, deodorants, fly sprays, adhesives and so on.'

'Spraying of those products leads to the release of a substance as an aerosol into the air or onto a surface, depending on the purpose of the application. The release of the substance of interest from an aerosol into the air can be modelled using the spray models in ConsExpo Web. Two models are currently available: a low-tier model describing the instant release of a substance into the air, and a more sophisticated model called the spray model.'

'The model’s methodology is presented in a real-life scenario of a person using an air freshener in their living room.'

'The residential setting consists of a room in which the person uses the spray. The room can be described by providing the room volume and room height. The user of the spray product can be described by providing information on body weight and inhalation rate. In this example, the user is an adult. Once you have entered information about the room and the user, the next inputs relate to the aerosol and its constituents.'

'Next, describe the behaviour of the sprayed aerosols to a number of model parameters:
- The duration of spraying
- The mass generation rate describing the amount of product released per unit of time
The former two combined provide the total released amount
- The airborne fraction, which is the fraction of aerosols remaining airborne and thus available for inhalation
- The particle size distribution of the aerosols and how they disperse across the room
- And finally, the removal of aerosols from the air by gravitational settling and ventilation of the room'

'The physics of release and dispersion are quite complex. The instant release model simplifies the release and behaviour of the spray and the substance. It makes no allowance for the fact that some substances are released as aerosols or vapours. Furthermore, it does not take into account whether the product is used on a surface or not, which may affect the airborne fraction.'

'Instead, it assumes that a specified product amount is instantaneously released into the air. This model provides a conservative estimate of the concentration in the air and is used for situations where:
- a quick conservative estimate of the exposure is desired;
- information on the spray application and its use are lacking;
- volatile substances with a vapour pressure above 1 Pa are released by the spray application.
Such volatile substances evaporate almost immediately due to the high release area.'

'If additional product data are available and refinement is needed, the spray model can be used.'

'Similar to the first-tier approach, you need to enter the duration of spraying, mass generation rate, and exposure duration to describe the product use. Additional input is needed to describe the airborne fraction and particle size distribution.'

'The airborne fraction describes the amount of spray that is released into the air. This depends on the direction of the spray and type of spray product, meaning for example a trigger spray or aerosol.'

'The particle size distribution is an important parameter that determines what happens to the spray. Based on diameter size, the model simulates gravitational settling within a room. This is used to estimate the duration that spray will be available in the air. The smaller the spray amount, the longer it floats in the air and can be inhaled.
Besides gravitational settling, the model assumes an even distribution of aerosols across the room. In some cases, this assumption is not justified. When sprayed towards a person, you can assume that there is an initial cloud surrounding the breathing zone. The model crudely splits the first moments of release into the cloud, after which immediate dispersion into the room is considered.'

'A second way of removing spray is by ventilation. This works in a similar way across inhalation models and assumes a certain exchange with fresh air.'

'When using ConsExpo Web, the desired information is to be provided by the user. We use the example of an air freshener to show the functionality of the model. Please note the insert fields for the particle size distribution and the option to provide raw data.'

'We run through the input fields providing information on spray duration, mass generation rate, airborne fraction, and particle size distribution, which requires the median particle size and coefficient of variation.'

'Furthermore, we wish to highlight the requested cut-off diameter for inhalation. This means that smaller aerosols are available for inhalation, but bigger aerosols only for oral exposure. Note that bigger aerosols will drop to the floor rapidly, but some may still end up in the nasal and oral cavities, where they are assumed to be ingested. If you are interested in the integrated exposure to a spray, you need to tick the box marked ‘Include oral non-respirable material exposure’.'

'After completing the insert fields, the model can be simulated.'

'Running the spray model with the example in mind yields results for the concentrations in the air, exposure estimates, and graphs of the exposure event and how it evolves over time, defined by the exposure duration.'

'We hope this tutorial has helped you to familiarise yourself with ConsExpo Web. Our support does not end here. Visit the ConsExpo website for help pages that provide information on ConsExpo Web and a user manual. You can also access the ‘i’ and ‘?’ icons within the software, which are there to give you extra help when needed. If you still have questions or need assistance, please contact us at consexpo@rivm.nl.'

On-screen text: Interested in ConsExpo and its partnerships? ConsExpo Web: the online consumer exposure assessment tool. www.consexpo.nl, consexpo@rivm.nl, Consumer Exposure and ConsExpo on LinkedIn.
ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland) and Health Canada and the Netherlands Food and Consumer Product Safety Authority and the Ministry of Health, Welfare and Sport.

Deze video van het RIVM is een tutorial van de blootstellingsmodellen die huidblootstelling kunnen schatten binnen de software ConsExpo Web. De tutorial laat de verschillende modellen zien en geeft uitleg over hoe de modellen kunnen worden toegepast.

VOICE-OVER: 'Welcome to one of ConsExpo Web’s online tutorial's. This video will give you insight into the dermal exposure models that are used in the ConsExpo Web software.'

'The dermal exposure route is an important route of exposure to many consumer products. While some products are applied to the skin deliberately, such as cosmetics and personal care products, others may come into unintended contact with the skin due to spills, contact with contaminated surfaces, or deposition. In addition, substances may migrate from materials that come into contact with the skin.'

'The dermal exposure models that are included in ConsExpo Web provide the means to determine direct dermal exposure in various scenarios. The following dermal exposure models are included:
- Instant application
- Constant rate
These are followed by the scenario-based models:
- Rubbing off
- Migration
- Diffusion
We will now run through the models, starting with instant application.'

'The instant application model is typically used to simulate the use of cosmetics and personal care products, as consumers apply these directly onto the skin. It provides a conservative estimate of dermal exposure in cases where information on the use of the product is lacking.'

'The elements that are relevant for dermal exposure are the product amount, the weight fraction of the substance of interest, the skin area that comes into contact with the product, and the body weight of the consumer who is exposed.'

'For certain toxicological end points, the relevant dosage metric is dermal load. It can be estimated by multiplying the applied product amount with the substance concentration, and subsequently dividing by the skin surface area that comes into contact with the product. To obtain the dermal exposure expressed as a dose, exchange skin surface area with body weight in the formula.'

'The constant rate model introduces the element of time. The dermal contact is constant over time and expressed as an amount per unit of time. It is used when the dermal exposure has a continuous character, such as when applying spray-based products to the skin.'

'The first two dermal exposure models are relatively straightforward. The next models are more sophisticated and require detailed information.'

'The rubbing-off model is used in scenarios whereby the substance is rubbed off contaminated or treated surfaces during normal activities.'

'A typical scenario is that of a child playing on a floor or lawn that has been treated with a product. The model describes the process of coming into contact with a known contaminated surface during play during which the product is rubbed off and transferred onto the skin.'

'This model introduces two new exposure parameters to describe that process: the transfer coefficient and the dislodgeable amount.'

'The transfer coefficient describes the surface area per unit of time that is the skin effectively comes into contact with. The dislodgeable amount is defined as the amount that is transferred during that contact and is expressed as an amount per surface area of the object or floor.'

'Exposure is then determined by combining the duration of the contact, the contacted surface area, the transfer coefficient, and the dislodgeable amount. The exposure is limited to the surface area that the skin can come into contact with within the period of time, as specified by the transfer coefficient and the duration of the contact, or to the maximum treated surface area.'

'Dermal exposure may also occur during prolonged contact with materials, for example the clothes that a person is wearing. During that contact, substances may leach from the textile to the skin. This scenario is best described using the migration model.'

'The input parameter that is required for the migration model is called the leachable fraction. This describes the fraction of the product that migrates (i.e. leaches) onto the skin. Another factor to note is the skin contact factor. This parameter accounts for the fact that not all skin is in contact with the product or article. For example, when examining skin contact with bed sheets of a person wearing pyjamas, , only a certain fraction of their skin is in direct contact with the bed sheets.'

'The fifth dermal model included in ConsExpo Web describes exposure by means of the transfer of a substance from a product only when the substance reaches the outer layer of the product. This is a type of diffusion model. Examples of its use include when hands are submerged in a liquid or a known product layer comes into contact with the skin.'

'The model requires information on the concentration of the substance in the product and the product layer thickness. An important parameter in this model is the diffusion coefficient. It describes the speed at which the substance transfers through the product layer. Entering the exposure time allows the model to calculate the exposure, as the diffusion coefficient determines how much of a substance has reached the outer layer and is forms an exposure risk.'

'The models that describe dermal exposure through rubbing off, migration, and diffusion require parameters that are often difficult to obtain. ConsExpo Web and the fact sheets provide some helpful suggestions for defaults to aid users.'

'We hope this tutorial has helped you to familiarise yourself with ConsExpo Web. Our support does not end here. Visit the ConsExpo website for help pages that provide information on ConsExpo Web and a user manual. You can also access the ‘i’ and ‘?’ icons within the software, which are there to give you extra help when needed. If you still have questions or need assistance, please contact us at consexpo@rivm.nl.'

On-screen text: Interested in ConsExpo and its partnerships? ConsExpo Web: the online consumer exposure assessment tool. www.consexpo.nl, consexpo@rivm.nl, Consumer Exposure and ConsExpo on LinkedIn.
ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland) and Health Canada and the Netherlands Food and Consumer Product Safety Authority and the Ministry of Health, Welfare and Sport.

Deze video van het RIVM is een tutorial van de blootstellingsmodellen die orale blootstelling kunnen schatten binnen de software ConsExpo Web. De tutorial laat de verschillende modellen zien en geeft uitleg over hoe de modellen kunnen worden toegepast.

VOICE-OVER: 'Welcome to one of ConsExpo Web’s online tutorial's. This video will give you insight into the oral exposure models that are used in the ConsExpo Web software.'

'Oral exposure from using non-food consumer products is typically the result of unintended contact or related to the incorrect use of a product. Only teething rings and toys for the very young are intended for oral exposure.'

'Within ConsExpo Web, three types of oral exposure are distinguished. The first is direct ingestion from products or through contaminated fingers that come into contact with the mouth. The second is oral exposure to food packaging materials through the consumption of food. The third is secondary ingestion through the inhalation of aerosols from spray application.'

'The direct ingestion model is subdivided into three modes: the direct oral intake mode, the constant rate mode and the product mouthing mode.'

'Direct oral intake is a low-tier mode that describes the amount of the product ingested directly. It is suitable to describe accidental oral exposure or in cases when details regarding oral exposure are lacking. The mode requires information on the ingested amount, the weight fraction of the substance, and body weight to determine the exposure per unit of body weight.'

'The constant rate mode describes ingestion per unit of time. This mode can be used to refine the direct oral intake mode when information on the period of time someone has ingested a product or material is available. The mode requires a rate and duration. It can also be used to describe mouthing behaviour. However, a more suitable mode to describe mouthing behaviour is described next.'

'The product mouthing mode describes the migration process of a substance to the mouth during mouthing. The migration rate is described as the amount of substance that is released per product surface area mouthed per second. This mode is used for typical mouthing scenarios with toys or baby products and when the migration rate is known. The more product is mouthed, the longer and the faster a substance is released, and therefore the higher the exposure will be.'

'The next model is the migration from packaging material model. It describes indirect exposure to substances from packaging material that migrated into the food. It has two modes describing the way a substance migrates from the packaging material to the food: the instant release mode and the constant release mode.'

'The model describes the step during which the substance migrates from the packaging material to the food, which is then consumed. When selecting the constant release mode, storage time is relevant to determine the concentration that may have already migrated to the food prior to consumption. The information on migration is vital for the use of this model.'

'Finally, a model is available to the user that describes secondary ingestion resulting from the inhalation of spray particles. This model is an option when using the spray model. In the spray model, there is a tick box marked ‘Include oral non-respirable material exposure’. When selected, the model assumes that inhaled spray particles that do not enter the respiratory tract are ingested. By default, it considers sprays in the range between 15 and 50 micrometres in diameter. The model calculates the oral exposure itself and does not require more information than already required for the spray model.'

'We hope this tutorial has helped you to familiarise yourself with ConsExpo Web. Our support does not end here. Visit the ConsExpo website for help pages that provide information on ConsExpo Web and a user manual. You can also access the ‘i’ and ‘?’ icons within the software, which are there to give you extra help when needed. If you still have questions or need assistance, please contact us at consexpo@rivm.nl.'

On-screen text: Interested in ConsExpo and its partnerships? ConsExpo Web: the online consumer exposure assessment tool. www.consexpo.nl, consexpo@rivm.nl, Consumer Exposure and ConsExpo on LinkedIn.
ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland) and Health Canada and the Netherlands Food and Consumer Product Safety Authority and the Ministry of Health, Welfare and Sport.

Deze video van het RIVM is een tutorial van de analytische mogelijkheden binnen de software ConsExpo Web. Het toont de mogelijkheden van een probabilistische schatting en gevoeligheidsanalyses.

VOICE-OVER: 'Welcome to one of ConsExpo Web’s online tutorials. Previous ConsExpo Web tutorials have helped you perform simulations within the programme. You are now ready to explore the analytical options available to you within ConsExpo Web. This video will give you guidance on how to perform probabilistic assessments and sensitivity analyses, as well as teaching you about the different ways to display the model results graphically.'

'Performing a probabilistic analysis provides insight into the exposure distribution. It can show the range and ratio between high-end exposed subjects or the exposure situation and median or average exposures.'

'Performing probabilistic assessments starts with using distributional data as inputs for a single parameter or multiple parameters. Care should be taken that the distributional data are not correlated. Such correlations result in unrealistic combinations of input data. When using distributional data for inputs such as product amount and treated surface area, for example, you should make sure that the extremes of the distributional data are still realistic when combined. For example, it is not possible to cover 100 square metres of wall with one litre of paint. Make sure that such a combination cannot exist. Alternatively, use a fixed value for one of the parameters.'

'You can add distributional data to a parameter in ConsExpo Web by clicking on the button with the parabola symbol. This gives access to entry fields where users can indicate the type of distribution to be used and enter the required information. For example, if a uniform distribution is selected, the user must enter a lower and upper bound value. The other options are normal, lognormal, triangular and beta distributions.'

'Probabilistic calculations are performed using a one-dimensional Monte Carlo simulation with a minimum of 1,000 and a maximum of 50,000 runs. It cannot discern variability from uncertainty. Here, the users themselves need to study the input data to determine if the input and output distributions are mainly the result of variability, uncertainty, or both.'

'If at least one input parameter contains distributional data, ConsExpo Web will run probabilistic calculations and yield outputs containing the mean, median, standard deviation as well as 95th and 99th percentile values of the exposure estimates.'

'By clicking on the plot distribution, users can access both a histogram of the distribution and a cumulative fraction plot, as shown in the graph. A link below the graph reads ‘Show data table’. Clicking on that link shows a tabular representation of the histogram.'

'The sensitivity analysis feature allows users to investigate which parameters have a major or minor impact on the selected output. This way, users are able to evaluate what parameter value has the highest impact on the output. A sensitivity analysis can be performed after a simulation of the exposure.'

'Users select the sensitivity settings for exposure route, input parameter, and output in the output window on the ‘Sensitivity analysis’ tab. Depending on the exposure route and output, users can select a variety of input parameters to perform the sensitivity analysis. An input range is required for the parameter to be evaluated. The analysis shows the relation between the input parameter for the specified range and the output (e.g. a mean event concentration).'

'In the case of an exponential relationship, for example, the impact of an input parameter change can either be significant or almost minimal, depending on the input range.'

'The results of the sensitivity analysis can be exported using the standard ConsExpo Web functionalities for copying graphs and exporting data tables.'

'We hope this tutorial has helped you to familiarise yourself with ConsExpo Web. Our support does not end here. Visit the ConsExpo website to find help pages that provide information on ConsExpo Web and a user manual. You can also access the ‘i’ and ‘?’ icons within the software, which are there to give you extra help when needed. If you still have questions or need assistance, please contact us at consexpo@rivm.nl.'

On-screen text: Interested in ConsExpo and its partnerships? ConsExpo Web: the online consumer exposure assessment tool. www.consexpo.nl, consexpo@rivm.nl, Consumer Exposure and ConsExpo on LinkedIn.
ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland) and Health Canada and the Netherlands Food and Consumer Product Safety Authority and the Ministry of Health, Welfare and Sport.

Deze video van het RIVM is een tutorial over hoe de factsheets binnen het ConsExpo project worden ontwikkeld en gebruikt voor blootstellingschattingen. Het beschrijft tevens de link tussen de ConsExpo Web software, de database en de factsheets. De factsheets bevatten standaardwaarden die ingelezen kunnen worden in de software.

VOICE-OVER: 'Welcome to one of ConsExpo Web’s online tutorials. This video will give you insight into how to create exposure scenarios and how they are incorporated into the ConsExpo Web software. Background information on default values used in generic exposure scenarios and references to underlying sources are available in the published ConsExpo fact sheets.'

'An exposure assessment starts with the creation of an exposure scenario. The exposure scenario describes the consumer’s use of the product containing the substance of interest in a particular residential setting. In short, the four elements considered in an exposure scenario are the product, the substance, the consumer (or population), and the residential setting. To create the exposure scenario, you will need to enter information about these four elements.'

'Typical variables to consider within the exposure scenario relate to questions such as the following:
- The typical consumer: is it an adult or a child?
- Where is the product being used?
- How much of the product is needed?
- For how long is the consumer using it?
- How much of the substance is released?
- Is it a very volatile substance?
- Will the exposure scenario lead to dermal, oral, or inhalation exposure?'

'As the number of consumer products and the ways in which they are used varies, information may not be readily available. Moreover, it is important in regulatory assessments that exposure assessments are performed in a harmonised and standardised way.'

'ConsExpo fact sheets provide just that. They are an important part of the ConsExpo project and fact sheet data are an integral part of the ConsExpo software. Users can access the fact sheet data through a database within ConsExpo Web, shown later on in the video.'

'As of 2022, there are eight fact sheets. There is one fact sheet, the general fact sheet, dedicated to providing information on residential settings, population data, and so-called anthropometric data. The general fact sheet provides default information on room volumes, room heights, ventilation rates, body weights, and skin surface areas. It provides data that is typical for the Dutch or European environment, but covers information from other parts of the world as well.'

'The other fact sheets are based on product categories such as paints, cleaning agents, cosmetics, DIY products, and pest control products. These product fact sheets were created following extensive literature research and consultations with the industry and on product use information. The product categories are subdivided into product groups and subtypes. For example, the DIY fact sheet contains a product group called ‘glues and adhesives’, which in turn includes hobby glues, spray glues etc. Exposure scenarios are created at the product level and are defined by their exposure characteristics.'

'The product fact sheets connect the exposure scenarios for the relevant products to the information required by the ConsExpo Web software. To do so, the fact sheets describe the scenario and provide suggestions for the exposure models to use. Furthermore, they provide recommended default inputs for the requested exposure scenario. Users still need to check if the input is appropriate for their own assessment and provide specific product and substance information, such as the weight fraction of a substance.'

'A quality factor is assigned to the input parameters to indicate the quality of the information. This ‘Q factor’ indicates how many underlying data support the parameter value and its appropriateness in the exposure scenario. The Q factor aids the user in assessing whether the parameter value may be too uncertain and whether they should perhaps look up more suitable information.'

'Users can consult the database by selecting ‘Use fact sheets’ at the assessment level or scenario level. For example, if a user selects the product group ‘DIY products’ > ‘Glues’ > ‘Hobby glues’ for the usage phase, the database shows a screen describing the input parameters for that particular scenario. The user can then decide to save this scenario and complete the exposure assessment (i.e. enter the remaining information required) before simulating the assessment).'

'The fact sheets and ConsExpo Web software are recommended as a basis for exposure assessments within the context of REACH regulation and the Biocidal Products Regulation. Please note that users are ultimately responsible for the parameter values used in the exposure assessment. After accepting the default suggestions in the database for the scenario, users can make changes to these default inputs at their discretion.'

'We hope this tutorial has helped you to familiarise yourself with ConsExpo Web and its fact sheets. Our support does not end here. Visit the ConsExpo website for help pages that provide information on ConsExpo Web and a user manual. You can also access the ‘i’ and ‘?’ icons within the software which are there to give you extra help when needed. If you still have questions or need assistance, please contact us at consexpo@rivm.nl.'

On-screen text: Interested in ConsExpo and its partnerships? ConsExpo Web: the online consumer exposure assessment tool. www.consexpo.nl, consexpo@rivm.nl, Consumer Exposure and ConsExpo on LinkedIn.
ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland) and Health Canada and the Netherlands Food and Consumer Product Safety Authority and the Ministry of Health, Welfare and Sport.

Tutorial on the Probabilistic Aggregate Consumer Exposure Model, PACEM for short.

VOICE-OVER: Hello, everyone. Welcome to the tutorial on the Probabilistic Aggregate Consumer Exposure Model, or PACEM for short.

This video will provide an explanation of the underlying methodology used in PACEM. In addition, an illustrative example will be given of how to perform a risk assessment with this model. But first, let’s get a quick overview of the applicability of PACEM and why to use it in the first place.

Some chemical substances, for example fragrances and preservatives, are used in many different consumer products. To estimate the total daily exposure of a person or population, exposures to the chemical from all products used on that day need to be considered.

PACEM has been developed for this purpose. PACEM is designed to estimate aggregate exposure to chemicals in various consumer products by considering various factors, including usage patterns in a population, product types, and chemical concentrations in the products. It uses a probabilistic approach to provide a comprehensive exposure assessment of a population of interest.

To perform such a probabilistic exposure assessment, PACEM uses information about product-use frequencies and product-usage amounts of hundreds to thousands of individuals; this information is gathered in surveys.

The individuals questioned in the surveys form the basis of the simulated population. Specifically, the product-use frequencies and product amounts reported by the individual are used to simulate product-usage diaries.

These describe which products are used on each day of a 14-day period. For each product used on a given day, a product amount is sampled from the usage information as well.

Once the usage diary has been created, substance concentrations are sampled for each product and each individual in the usage diary. These concentrations are based on input provided by the user of PACEM.

To calculate an individual’s exposure to a particular substance, the product amount used is multiplied by the substance concentration in that particular product. Then, all exposures within a given day of the usage diary are summed, such that an aggregated exposure is estimated for each 24-hour time frame for an individual in a two-week period.

PACEM supports two endpoints of exposure: short-term exposure and long-term exposure. When selecting short-term exposure, the day with the highest aggregate exposure is taken from the 14-day diary. When selecting long-term exposure, the average aggregate exposure is taken from the 14 days. This allows users to select an endpoint that fits their exposure and risk assessment best.

Now that you have a global idea of the methodological concepts of PACEM, let’s take a look at the steps required to perform an exposure assessment.

(On-screen text: www.pacemweb.nl)

VO: In the first panel of PACEM, the user can select the product groups of interest, being personal care products and/or household cleaning products. Then, two types of exposure assessments can be selected: dermal load and systemic exposure. Finally, the population needs to be selected.

Currently, France, Germany, Spain, the Netherlands and the UK are included in PACEM, which refers to the product usage surveys conducted for individuals of those countries.

Then, in the next panel, relevant product groups need to be selected. Here, we select aftershave spray, after-sun cream, and liquid all-purpose cleaner.

For each selected product group, substance concentrations need to be provided, as well as the percentage of products containing the substance. This user input is needed to link substance concentrations to the product usage diaries that are created based on the surveys.

The last step on this panel is to provide exposure fractions, or retention factors if performing dermal load assessment.

These fractions are needed to account for situations where not all the used products lead to actual exposure, for example due to rinsing off. Exposure fractions and retention factors are represented by a value between 0 and 1, with 0 representing no exposure, and 1 representing exposure to all of the substance used during an event. The fractions implicitly comprise information on the exposure duration, the release of the substance from the product, contact between user and product and the relevant exposure routes.

User input can be provided as point values, but also as distributions. This can be done by clicking on the button with the distribution symbol. This will open a panel where users can select the type of distribution they want to use and provide the necessary input to define that distribution. By clicking on ‘Apply’, the selected distribution will be used by PACEM.

Once the product exposure settings have been provided, one can specify the absorption fractions for each exposure route. For this example, we assume 50% inhalation and dermal absorption.

In the next panel of PACEM, the Simulation Settings panel, users can choose the product sample size. This number reflects the number of times an individual is sampled from the information in the survey. Higher numbers will give more precise results, but the simulation will take longer to run. Upon clicking on the submit button, the exposure assessment will be sent to the PACEM server and the calculations will start. Information on the status of the computations are provided.

Once the status of the computations turns to ‘Success’, users can click on the Analysis button to analyse the results.

We can now take a look at the results and select the endpoints that we want to see. In this example, we will take a look at short-term exposure of all females in the population. You can also see the option to select exposed individuals only, or the entire population. By clicking on Create Output, we can now see the estimated aggregate exposure for the selected population.

Since we selected systemic exposure in the assessment settings of this example, an aggregate exposure will be shown for each exposure route, as well as the total aggregate exposure. If dermal load was selected, only the dermal load would have been shown. For each exposure route, various percentiles of the population exposure are given.

In addition, a visualisation of the cumulative exposure is shown below. Finally PACEM offers various options to export the results, by clicking on this symbol with the three horizontal lines.

To summarise, you now hopefully understand how to perform an exposure assessment with PACEM, and have a global understanding of the underlying principles.

We hope this tutorial has helped you to familiarise yourself with PACEMWeb. Our support does not end here. Visit the PACEM website to find help pages that provide information on PACEMWeb and a user manual. You can also access the ‘i’ and ‘?’ icons within the software, which are there to give you extra help when needed. If you still have questions or need assistance, please contact us at pacemweb@rivm.nl.

(On-screen text: Acknowledgement. ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland), Health Canada, the Netherlands Food and Consumer Product Safety Authority and the Dutch Ministry of Health, Welfare and Sport.)

Worked example showcasing the functionality of ConsExpo Web software in an exposure assessment. The worked example is based on a scenario for an all-purpose cleaner.

VOICE-OVER: Welcome to one of ConsExpo Web's online tutorials. This video will run you through a worked example showcasing the functionality of ConsExpo Web software in an exposure assessment.

The worked example is based on a scenario for an all-purpose cleaner. The exposure to chemical X is assessed for both short-term peak exposure and long-term exposure.

The scenario is described as follows: the product user sprays an amount of product on a surface. The surface is then rinsed with a cloth. After the cleaning has taken place, a child plays on the surface that has been cleaned. The all-purpose cleaner can be used everywhere in the house, but is typically used for a small surface up to about 1 m2.

From this description we establish two phases of application, namely the spraying phase and consequently rinsing phase. In addition, we have a post-application phase describing the exposure of chemical X to a child while playing. In ConsExpo Web, a separate assessment is required in case a different subpopulation is considered. Thus, for the worked example we will create two assessments, starting with the adult user of the spray.

It is important to realise that ConsExpo requires information on product, substance, exposed person and residential settings.

First, we consider the spraying of the all-purpose cleaner. In case the volatility is unknown or known to be high, the first tier spray model for volatile substances should be selected. Here, we regard chemical X as non-volatile and select the spray model. We use the use factsheet functionality in ConsExpo to select the cleaning and washing factsheet, all-purpose cleaner and finally the all-purpose cleaner spray. Then select the option for non-volatile substances. The factsheets provide underlying information for this standard scenario. As the assessor you have to make sure that the scenario in the fact sheet matches your own scenario. The scenario description can be found in the cleaning agents fact sheet. It is a perfect match, except for the spraying location. Since it can be used everywhere, we need to adapt the room volume and room ventilation to match the defaults for an unspecified room, as described in the General fact sheet.

Product and substance specific information next to population information is to be added to complete the scenario. When all insert fields are filled in for the inhalation exposure, the exposure can be simulated.

Within this assessment a second scenario can be added in the same way as the spraying scenario was created. Using the use factsheet button under scenario, the scenario for rinsing can be selected and created, with again the necessary changes as previously indicated.

The exposure assessment can be simulated for both scenarios simultaneously. The exposure estimated for the dose can be summed to determine the exposure resulting from both spraying and wiping. But be aware that ConsExpo does not limit the exposure estimate for mass balance. Each scenario is calculated as if the product amount is independent of the other.

If a health reference value is available for chemical X, the assessor can compare the different exposure metrics ConsExpo provided with the reference value to see if risks are sufficiently controlled.

The exposure assessment then continues with a new assessment for the child playing on the treated surface. Again, there is a scenario available from the factsheets that describes the rubbing off of substance from a treated surface. The duplicate assessment button can be pressed to create a duplicate that can serve as the basis for the new assessment. First, change the assessment settings regarding the population of interest. Then, the scenarios previously set up for the application should be removed and a new scenario should be created for the post-application phase. But there is a catch.

Using the use factsheet functionality in ConsExpo to select the cleaning and washing factsheet, all-purpose cleaner and finally the all-purpose cleaner spray, one cannot find a post-application phase. However, there is a post-application phase in the all-purpose cleaner liquid. This makes sense. Typically one does not use sprays for large surface areas, but rather use a liquid cleaner. In our situation though, we do consider a post application phase where a child plays on the treated surface.

To accommodate the scenario of the exposure of a playing child to an area treated with the spray, the assessor reassesses the treated area and reduces the default parameter value for contacted surface to, in this example, 1 m2.

Also note that the spraying takes place every day. The frequency of the use of the liquid is much lower. The scenario therefore needs another adjustment regarding the frequency. Probably not all spray applications are on surfaces where a child will play. In the example, it is assumed that this scenario follows the information on frequency for the cleaner liquid. The frequency of play on a treated surface is 197 times per year.

If inhalation exposure during the spray application is expected for the child as well, a separate scenario should be added as described for the adult user previously. For now, we continue with the dermal exposure route only.

The scenario is now completed and can be run by clicking the simulate button. Both the dermal load and dermal systemic exposure are provided. Dependent on the type of health reference value, possibly specific for this target population, one can compare the appropriate dose metric with the reference value and see if risks are sufficiently controlled.

Using the functionality in ConsExpo under the assessments window, one can create a report per assessment for multiple scenarios, create graphs and so on. Outside of ConsExpo Web, the assessor needs to report their findings regarding the risks. The features of ConsExpo end with the exposure assessment.

We hope this tutorial has helped you to familiarise yourself with ConsExpo Web. Our support does not end here. On the ConsExpo website, you can find Help-pages that provide information on ConsExpo Web, and a user manual. You can also access the 'i' and '?' icons within the software which are there to give you that extra help when needed. If you still have questions or need assistance, please contact us at: consexpo@rivm.nl.

On-screen text: Acknowledgement. ConsExpo Web is realized with contributions of the counterpart institutes ANSES (France), BfR (Germany), FOPH (Switzerland), Health Canada, the Netherlands Food and Consumer Product Safety Authority and the Dutch Ministry of Health, Welfare and Sport.

Tutorial for using ConsExpo Web's 'emission from solid materials' model to estimate the inhalation of substances evaporating from solid materials in an indoor environment.

VOICE-OVER: Welcome to the tutorial for using ConsExpo Web's 'emission from solid materials' model to estimate the inhalation of substances evaporating from solid materials in an indoor environment. The tutorial includes an introduction, a description of the model concept, descriptions of the input fields for which the user needs to insert values that fit the exposure scenario, and a demonstration on how to interpret the model outcomes.

The 'emission from solid materials' is one of the inhalation exposure models that ConsExpo Web has to offer. It is most suitable for consumer exposure scenarios for volatile or semi-volatile substances that are slowly released from solid
materials in an indoor environment, such as furniture, floors, walls or objects.

'Emission from solid materials' can be selected in the model dropdown menu at ConsExpo Webs 'inhalation' tab.

The consumer is assumed to reside in the room with the solid material from which substances are emitted for a prolonged period of time, leading to a long term exposure duration of days, months or even years.

The 'emission from solid materials' model consists of three stages that simulate the diffusion of the substance in the solid material matrix, the partitioning behaviour at the interface of the material surface and a stagnant layer of air, and the mass transfer of substance from the stagnant air to the room air.

The following animation visualizes the fate of the evaluated substance expressed here as purple dots. Inside the solid material, the substance moves in randomly directed patterns driven by diffusion. Once the substance hits the interface
with the stagnant layer of air, it can leave the solid material. Here the substance is driven by partitioning behaviour, searching for thermodynamic equilibrium between the concentration in stagnant air and the material. As such, the substance may travel back into the material. Finally, the substance mass is transferred from the stagnant air into the room air in which the inhalation exposure scenario takes place.

Here, the input fields are described, so that the model user knows how to insert appropriate values fit for the consumer exposure scenario.

'The product surface area' refers to the area of the product material that is in contact with air. The unit varies from square centimetres for small objects to square meters for large surfaces, such as floors or walls.

The 'product thickness' describes how thick the layer of the product material is in which the substance is formulated. It may range, for example, from micrometres in the case of a layer of dried paint, millimetres for a piece of paper or centimetres for wooden boards or window panes.

The 'product density' refers to the density of the product material in which the substance of interest is formulated. It is expressed as a unit of mass per unit of volume, such as grams per cubic centimetre or kilograms per litre.

The diffusion coefficient is an input parameter that describes how fast the evaluated substance diffuses within the product material. As such, it depends on the properties of the substances, as well as the product material. The faster a substance diffuses, the less time it will take before it reaches the interfacial area from which it can evaporate into the stagnant air above the material. Consequentially, substances with high diffusion coefficients are more prone to rapid evaporation. Collecting the accurate data for the diffusion coefficient can be a challenging task, because diffusion coefficients may vary within orders of magnitude between substances and between product materials. The unit for diffusion coefficient is expressed as the squared distance per unit of time and is typically referred to as square meter per second.

The input field 'weight fraction' refers to the amount of substance formulated in the product per unit of product amount. Here, the product amount is the sum of the substance mass and the mass of the material it is formulated in. Typically weight fraction is unitless, because it refers to the amount of substance in grams divided by the amount of product in grams, but it can also be inserted as a weight percentage.

The product-air partition coefficient refers to the ratio of the substance concentration in the product material to the substance concentration of the product in air at thermodynamic equilibrium. Typically, partitioning coefficients
are symbolized by the letter K and by the two media between the substances partitions expressed in subscript. The partitioning coefficients don't depend on the initial concentration of the substance in the product, because it refers to a state of thermodynamic equilibrium. Substances with low product-air partitioning coefficients have little tendency to remain in the product and are as such driven to equilibrium at the air side. As a consequence, these substances are more prone to rapid evaporation from the solid product material. Just as with diffusion coefficients, collecting accurate data for the product-air partitioning coefficient can be a challenging task, because it may vary within orders of magnitude between substances and between product materials. The unit of the partitioning coefficient can be inserted as linear, but also as loglinear, because the concentrations across the two media can vary within orders of magnitude.

The emission from solid materials model is designed to simulate exposure scenarios over a long period of the time. As such, the exposure dose of the substance inhaled by the consumer does not only depend on the concentration of the substance in the room air, but also on the timeframe in which the consumer is present in the room. Some consumer products such as, for example, flooring agents and drain openers, advise that a period of time should elapse before entering the room after the product has been applied. This timeframe can be inserted in ConsExpo Web using the 'start exposure' and 'exposure duration' input fields. The start exposure input field refers to the amount of time between application of the product and entering the room. 'Exposure duration' refers to the amount of time the consumer then stays in the room.

The intensity of the exposure is calculated in ConsExpo as the air concentration in the room over time for which graphs and data tables are available. Here, it can be seen that the air concentration changes over time, so that the inhaled dose depends on the moments the consumer enters and leaves the room. This is to be inserted as 'start exposure' and the period of the time in which the consumer then stays in the room is to be inserted as 'exposure duration'.

The mass transfer coefficient expresses the velocity at which the substance in the stagnant layer of air above the product is transferred to the room air. Such transfer depends on a number of factors, such as the substance's molecular weight, the air flow over the product and the surface roughness of the product. The most recent ConsExpo Web fact sheets suggest a default value for the mass transfer coefficient of 10 meters per hour.

The 'emission from solid materials' model also includes 'room volume', 'ventilation rate', 'inhalation rate' as input fields and the 'absorption' model to calculate internal exposure doses. These are not explained in this tutorial, but are covered in the 'introduction to inhalation models tutorial' which explains the input fields and models that are common to all inhalation models.

We would like to acknowledge all partners in the ConsExpo project: Health Canada, the French Agency for Food, Environmental and Occupational Health and Safety, the German Federal Institute for Risk Assessment, the Swiss Federal Office of Public Health, the Netherlands Food and Consumer Product Safety Authority and the Dutch Ministry of Health, Welfare and Sport.

(SILENCE)