Toxicological Reference Value (TRV) - Establishment of Chronic Reference Value by inhalation for Titanium Dioxide under nanoform
Valeurs toxicologiques de référence - Le dioxyde de titane sous forme nanoparticulaire
Résumé
A toxicological reference value, or TRV, is a toxicological index qualifying or quantifying a risk to human health. It establishes the link between exposure to a toxic substance and the occurrence of an adverse health effect. TRV are specific of a duration of exposure (acute, subchronic or chronic) and a route of exposure (oral or inhalation). The construction of TRV differs according to the knowledge or assumptions made about the mechanisms of action of the substances. Currently, the default assumption is to consider a monotonous relationship between exposure, or dose, and effect, or response. Based on current knowledge and by default, it is generally considered that, for non-carcinogenic effects, toxicity is only expressed when a dose threshold is exceeded (Anses, 2017a).
In practice, the construction of a TRV involves the following steps:
- identify and analyse available toxicity data, based on epidemiological and/or experimental
studies;
- identify the target organ(s) and critical effect;
- identify the establishment assumption, with or without a dose threshold, depending on the
mode of action of the substance;
- choose a key study of good quality that allows establishing a dose-response relationship;
- define a critical dose in humans or animals from this study, and in the case of a critical dose
obtained in animals, adjust this dose to humans;
- for a threshold TRV, apply uncertainty factors to this critical dose in order to derive a TRV
applicable to the entire population concerned;
- for a TRV without threshold, perform a linear extrapolation at the origin to determine an
excess of unit risk.
The development of TRVs follows a highly structured and stringent approach involving collective evaluations by groups of specialists.
Le dioxyde de titane sous forme nanoparticulaire est utilisé dans de nombreuses applications industrielles et commerciales. Dans le cadre de sa mission nationale d’élaboration de valeurs sanitaires de référence, l’Anses a été chargée de définir une Valeur Toxicologique de Référence (VTR) pour le dioxyde de titane sous forme nanoparticulaire (TiO2 -NP). Suite à une analyse approfondie de l’ensemble des données de toxicité disponibles, l’Agence recommande une VTR chronique par inhalation pour la forme P25 du TiO2-NP de 0,12 µg.m-3. A partir de cette valeur de référence, des évaluations de risques sanitaires seront menées dans le cadre des actions de gestion des installations et sites industriels en France. Il s’agit par ailleurs, de la première VTR élaborée pour un nanomatériau en France.
Origine : Accord explicite pour ce dépôt
Loading...
