Abstract
The present pilot study tested the efficiency of nanoTiO2 sunscreen to prevent the oxidative stress/inflammation caused by ultraviolet (UV) radiation using biomarkers in subjects’ blood, urine, and exhaled breath condensate (EBC). In addition, the skin absorption of nanoTiO2 was studied. Six identical subjects participated in three tests: (A) nanoTiO2 sunscreen, (B) UV radiation, and (C) sunscreen + UV. The first samples were collected before the test and the second after sunscreen application and/or UV exposure. On day 4, the third samples were collected, and the sunscreen was washed off, and the fourth samples were collected on day 11. The following biomarkers were measured: malondialdehyde, 4-hydroxy-trans-hexenal, 4-hydroxy-trans-nonenal, aldehydes C6-C12, 8-iso-Prostaglandin F2α, o-tyrosine, 3-chlorotyrosine, 3-nitrotyrosine, 8-hydroxy-2-deoxyguanosine, 8-hydroxyguanosine, 5-hydroxymethyl uracil, and leukotrienes, using liquid chromatography-electrospray ionisation-tandem mass spectrometry. Titania was measured using inductively coupled plasma mass spectrometry and TiO2 nanoparticles by transmission and scanning electron microscopy. Sunscreen alone did not elevate the markers, but UV increased the biomarkers in the plasma, urine, and EBC. The sunscreen prevented skin redness, however it did not inhibit the elevation of oxidative stress/inflammatory markers. Titania and nanoTiO2 particles were found in the plasma and urine (but not in the EBC) in all sunscreen users, suggesting their skin absorption.
Highlights
Skin cancer prevention is important and sunscreen use has been recommended as a cost-effective preventative, especially in countries with a high-sunlight environment [1,2]
The absolute consumption was higher in males than in females (144.3 g versus 132.7 g respectively), the consumption per body surface in males (85.0 ± 4.8 g/m2) did not significantly differ from that in females (95.3 ± 6.1 g/m2) (p = 0.084)
Sunscreen alone did not cause an elevation in the vast majority of the biomarkers of oxidative stress and inflammation, tanning bed use increased all markers in plasma, urine, and exhaled breath condensate (EBC)
Summary
Skin cancer prevention is important and sunscreen use has been recommended as a cost-effective preventative, especially in countries with a high-sunlight environment [1,2]. It has been estimated that a majority of cancers could potentially be reduced by regular sunscreen use. It included around 9.3% of squamous cell skin carcinomas and 14% melanomas that may be prevented if UV exposure was reduced. Some studies have reported potentially unfavourable effects of sunscreens, since they can extend the duration of sunbathing and increase the risk of skin malignancies [3,4,5,6]. Other studies point to a high reactivity of nanoparticles and their potential to produce reactive oxygen species (ROS), alter the skin structure [7,8], and/or penetrate the skin [9]
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