Characterization of User PM Exposure During the Application of Aerosol Mineral-Based Sunscreens Shows Minimal Risk

This study characterizes particles emitted from three commercial sunscreen sprays with a sun protection factor (SPF) of 30. Sample collection and measurement were made at 20 cm longitudinally and 36 cm laterally from the emission point to simulate the point of inhalation for an application on one’s arm. Over 85% of all particles by count had a diameter of less than 100 nm. The three products had a mass median diameter of 0.65 µm, 1.40 µm, and 1.70 µm, respectively. The collected aerosols in the breathing zone from application of the sunscreen sprays with TiO₂ and ZnO contained less than advertised. The product containing only TiO₂ as active ingredient generated aerosols with a higher mass fraction of TiO₂. The total particle mass concentrations of the sunscreens were 0.77 µg/m³_, 0.57 µg/m³, and 0.80 µg/m³, respectively. The PM_2.5 mass concentrations were 0.45 µg/m³, 0.30 µg/m³, and 0.37 µg/m³, respectively. The estimated mass concentrations for total particles, PM_2.5, TiO₂, ZnO, and SiO₂ did not exceed the regulatory limits by the Occupational Health and Safety Administration (OSHA) or the recommended limits by the National Institute for Occupational Safety and Health (NIOSH), meaning 8-h daily average exposures at these levels throughout a typical career would comply with current regulations. Consequently, applying the three sunscreen sprays does not pose a significant hazard via respiratory exposure under these conditions, and considering the transient and relatively infrequent use by most consumers, a substantial factor of safety exists.