Chemical oxidation and DNA damage catalysed by inorganic sunscreen ingredients.
Titanium dioxide (TiO2) has been noted (US Federal Register, 43FR38206, 25 August 1978) to be a safe physical sunscreen because it reflects and scatters UVB and UVA in sunlight. However, TiO2 absorbs about 70% of incident UV, and in aqueous environments this leads to the generation of hydroxyl radicals which can initiate oxidations. Using chemical methods, we show that all sunscreen TiO2 samples tested catalyse the photo-oxidation of a representative organic substrate (phenol). We also show that sunlight-illuminated TiO2 catalyses DNA damage both in vitro and in human cells. These results may be relevant to the overall effects of sunscreens.
Dunford
R
R
University of Oxford, Department of Biochemistry, UK.
Salinaro
A
A
Cai
L
L
Serpone
N
N
Horikoshi
S
S
Hidaka
H
H
Knowland
J
J
D002374:Catalase / Q000494:pharmacology; D002460:Cell Line; D004247:DNA / Q000187:drug effects* / Q000528:radiation effects; D004249:DNA Damage; D006801:Humans; D010084:Oxidation-Reduction; D019800:Phenol / Q000528:radiation effects; D010777:Photochemistry; D010957:Plasmids / Q000187:drug effects* / Q000528:radiation effects; D013472:Sunlight; D013473:Sunscreening Agents / Q000633:toxicity*; D014025:Titanium / Q000633:toxicity*; D014466:Ultraviolet Rays; D015034:Zinc Oxide / Q000494:pharmacology
D013473:Sunscreening Agents; C009495:titanium dioxide; D019800:Phenol; D004247:DNA; D014025:Titanium; D002374:Catalase; D015034:Zinc Oxide