About ConsExpo nano, a short introduction to the tool for consumer exposure to nanomaterials in consumer spray products.

Consumers are potentially exposed to nanomaterials during use of nano-enabled consumer products. Of particular concern is the application of nanomaterials in spray products. To investigate the exposure of the consumer to nanomaterials in these products, RIVM developed a new software model: ConsExpo nano. This model was adapted from the ConsExpo model for the estimation of exposure to regular substances in spray products. It has been developed in the context of the NanoNextNl project: “Predictive modeling of human exposure”.

During use of a consumer spray product, the nanomaterial that is released from the spray may become airborne as part of the spray aerosol or as individual particles. Exposure to a nanomaterial in an aerosol may take place via different routes, but inhalation of the aerosol is generally considered the route of most concern.
According to Braakhuis et al. (2014), the most relevant effect after inhalation exposure to nanomaterials is the induction of inflammation in the alveoli. One of the most critical determinants of this effect is both the magnitude and duration of the alveolar load of a nanomaterial. To estimate the alveolar load arising from the use of nano-enabled spray products, ConsExpo nano combines models that estimate the external aerosol concentration in indoor air, with models that estimate the deposition in and clearance of inhaled aerosol from the alveolar region.

Another issue addressed in ConsExpo nano is the observation that the traditional choice of ‘mass of the substance inhaled’ as a measure of exposure is inappropriate to quantify dose-effect relations for nanomaterials. Alternative dose metrics such as total number or total surface area of the nanoparticles inhaled have been suggested, but consensus on an appropriate dose metric is currently lacking. To bridge this current knowledge gap, ConsExpo nano expresses exposure estimates in a variety of dose metrics, allowing the exposure assessor to evaluate various alternatives.

In April 2016, the tool is updated according to comments and suggestions from users. In the new version of the tool, version 1.1, two major changes have been implemented. First, apart from a spray scenario, the user is able to choose a custom scenario in which a known air concentration of aerosols (containing nanomaterials) can be entered directly into the tool. This option enables the user to calculate an alveolar load in lungs from any inhalation exposure (outside spray exposure), which makes the tool applicable for scenarios other than spray scenarios, including those occuring at the workplace.
Furthermore, there is a possibility to enter exposure parameters of an animal hazard study with known adverse effects after inhalation exposure to a nanomaterial. In this way, it is possible to convert the external dose of nanomaterials to which the animals are exposed, into an internal exposure dose i.e. the alveolar load. In this way, a comparison (indication of risk) can be based on comparison of the alveolar load.

Currently, there is still a lack of knowledge and data on the exposure assessment and risk assessment for nanomaterials. ConsExpo nano is a “work-in-progress” online tool that is designed to reflect the current state of knowledge on exposure to nanomaterials via inhalation. See also the Proclaimer for the use of the ConsExpo Nano online tool. The tool will be further developed to accommodate developments in the state of the science.
We therefore highly appreciate your comments and additional information to improve the model. Please send your comments to consexpo@rivm.nl.

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