BACKGROUND: Photoinstability of sunscreens because of ultraviolet (UV) exposure is a well-known and common phenomenon. Recently, it was also shown that sunscreens with complex filter combinations are photoinactivated by UV exposures, which can easily be acquired by solar exposure over several hours. OBJECTIVES: To assess the change of the spectral transmission after UV exposure (UV-challenged protective performance) of 27 commercially available photoprotective lipsticks. METHODS: Quartz slides were covered with a lipstick layer (area density 1.0+/-0.1 mg/cm2) and irradiated with increasing doses of solar-simulated radiation. The spectral transmission (T) was measured spectrophotometrically before and after 5, 12.5, 25, and 50 standard erythema doses (SED) of exposure. We calculated the change in transmission (photoinstability) as the difference between the spectral transmission before and after a defined UV exposure, DeltaT, and the arithmetic mean, for both the UVA (DeltaTA) and UVB (DeltaTB) ranges. A product was labelled as photounstable if the mean photoinstability in the UVA, DeltaTA, or UVB range, DeltaTB, was higher than 5% for an UV exposure of 12.5 SED. RESULTS: Eleven products showed a significant photoinstability in the UVA range (DeltaTA between 6% and 27%), only one product in the UVB range (DeltaTB = 13%), and one product in both the UVA (DeltaTA = 31%) and UVB (DeltaTB = 9%) range. In one product photoinstability became significant in the UVA range at higher UV exposures. CONCLUSIONS: Out of 27 lipsticks only 13 products showed a photostable performance (DeltaTA < 5% and DeltaTB < 5% for 12.5 SED). We propose therefore that only products, which fulfil these UV photostability criteria should be marketed.
BACKGROUND: Photoinstability of sunscreens because of ultraviolet (UV) exposure is a well-known and common phenomenon. Recently, it was also shown that sunscreens with complex filter combinations are photoinactivated by UV exposures, which can easily be acquired by solar exposure over several hours. OBJECTIVES: To assess the change of the spectral transmission after UV exposure (UV-challenged protective performance) of 27 commercially available photoprotective lipsticks. METHODS: Quartz slides were covered with a lipstick layer (area density 1.0+/-0.1 mg/cm2) and irradiated with increasing doses of solar-simulated radiation. The spectral transmission (T) was measured spectrophotometrically before and after 5, 12.5, 25, and 50 standard erythema doses (SED) of exposure. We calculated the change in transmission (photoinstability) as the difference between the spectral transmission before and after a defined UV exposure, DeltaT, and the arithmetic mean, for both the UVA (DeltaTA) and UVB (DeltaTB) ranges. A product was labelled as photounstable if the mean photoinstability in the UVA, DeltaTA, or UVB range, DeltaTB, was higher than 5% for an UV exposure of 12.5 SED. RESULTS: Eleven products showed a significant photoinstability in the UVA range (DeltaTA between 6% and 27%), only one product in the UVB range (DeltaTB = 13%), and one product in both the UVA (DeltaTA = 31%) and UVB (DeltaTB = 9%) range. In one product photoinstability became significant in the UVA range at higher UV exposures. CONCLUSIONS: Out of 27 lipsticks only 13 products showed a photostable performance (DeltaTA < 5% and DeltaTB < 5% for 12.5 SED). We propose therefore that only products, which fulfil these UV photostability criteria should be marketed.
Authors: Sérgio Schalka; Denise Steiner; Flávia Naranjo Ravelli; Tatiana Steiner; Aripuanã Cobério Terena; Carolina Reato Marçon; Eloisa Leis Ayres; Flávia Alvim Sant'anna Addor; Helio Amante Miot; Humberto Ponzio; Ida Duarte; Jane Neffá; José Antônio Jabur da Cunha; Juliana Catucci Boza; Luciana de Paula Samorano; Marcelo de Paula Corrêa; Marcus Maia; Nilton Nasser; Olga Maria Rodrigues Ribeiro Leite; Otávio Sergio Lopes; Pedro Dantas Oliveira; Renata Leal Bregunci Meyer; Tânia Cestari; Vitor Manoel Silva dos Reis; Vitória Regina Pedreira de Almeida Rego Journal: An Bras Dermatol Date: 2014 Nov-Dec Impact factor: 1.896