Particle size distribution in the evaluation of the inhalation toxicity of cosmetic spray products

While applying cosmetic sprays (pump sprays and propellant-based sprays) intended for use on the skin or hair, consumers may unintentionally inhale sprayed droplets/particles. Thus, it is essential to analyze the size dis-tribution of sprayed droplets/particles because those less than 10 mu m are considered to be respirable and may present a high systemic and local exposure risk. In this study, we investigated the droplet/particle size distri-bution of 78 cosmetic sprays by laser diffraction. Our results showed that the level of respirable droplets/par-ticles released by pump sprays averaged 0.5% of all particles measured (0.00%-2.23%) and that released by propellant-based sprays averaged 15.25% (0.15%-32.27%). Dry shampoos (powder) released the highest per-centage of respirable droplets/particles (16.66%-32.27%). A default value of 25% of respirable droplets/parti-cles can also be suggested for dry shampoos. Droplet/particle size distribution was influenced by the spray dispensing system (pump or propellant-based), the product type (hairspray, sunscreen, etc.) and the galenic form (powder, oil, emulsion, etc.). However, it should be noted that more confidence is placed in the pump spray data due to the larger sample size. This study provides data on droplet/particle size, which may be used in a modelling approach to predict inhalation exposure. Therefore, it must be known and used, together with assessments of intrinsic and local toxicities to determine the margin of safety of the product by inhalation route, and to assess the risk of cosmetic sprays.