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594511 
Journal Article 
Lack of significant dermal penetration of titanium dioxide (TiO2) from sunscreen formulations containing nano- and sub-micron-size TiO2 particles 
Sadrieh, N; Wokovich, AM; Gopee, NV; Zheng, J; Haines, D; Parmiter, D; Siitonen, PH; Cozart, CR; Patri, AK; Mcneil, SE; Howard, PC; Doub, WH; Buhse, LF 
2010 
1 
Toxicological Sciences
ISSN: 1096-6080
EISSN: 1096-0929 
115 
1 
156-166 
English 
20156837 
WOS:000276742200015 
Titanium dioxide (TiO(2)) is included in some sunscreen formulations to physically block UV radiation. A dermal penetration study was conducted in minipigs with three TiO(2) particles (uncoated sub-micron sized, uncoated nano- or aluminum hydroxide, dimethicone/methicone copolymer-coated nano-sized) applied 5% by weight in a sunscreen. These and control formulations were topically applied to minipigs at 2 mg cream/cm(2) skin (4 applicatons/day, 5 days/week, 4 weeks). Skin (multiple sites), lymph nodes, liver, spleen and kidneys were removed, and the TiO(2) content was determined (as titanium) using inductively coupled plasma mass spectroscopy (ICP-MS). Titanium levels in lymph nodes and liver from treated animals were not increased over the values in control animals. The epidermis from minipigs treated with sunscreens containing TiO(2) showed elevated titanium. Increased titanium was detected in abdominal and neck dermis of minipigs treated with uncoated and coated nanoscale TiO(2). Using electron microscopy-energy dispersive X-ray analysis (ED-EDX), all three types of TiO(2) particles were found in the stratum corneum and upper follicular lumens in all treated skin samples (more particles visible with coated nanoscale TiO(2)). Isolated titanium particles were also present at various locations in the dermis of animals treated with all three types of TiO(2)-containing sunscreens, however, there was no pattern of distribution or pathology suggesting the particles could be the result of contamination. At most, the few isolated particles represent a tiny fraction of the total amount of applied TiO(2) . These findings indicate that there is no significant penetration of TiO(2) nanoparticles through the intact normal epidermis. 
Sunscreen; TiO2; Nano; skin 
02/15/2010 
02/15/2010 
• Nanoscale Carbon