zinc oxide and titanium dioxide with nanotechnology

nytimes.com - What to Look for in a Sunscreen
"The ideal sunscreen would be a physical block using titanium dioxide or zinc oxide."

Pros
Enhanced sun protection of nano-sized metal oxide particles over conventional metal oxide particles: An in vitro comparative study.pdf
"The skin cosmetics containing the titanium or zinc oxide nanoparticles were found to have improved spreadability as compared to skin cosmetics containing conventional titanium or zinc oxide particles, respectively. All skin cosmetics were found to have uniform distribution of the particles."

healthcentral.com - Are Sunscreens Containing Zinc Oxide Nanoparticles Safe?
"nanotech-based sunscreens may be among the safest and most effective on the market.” [2] Further, the group reviewed 15 studies and found that, in healthy skin, there was no absorption of the nanoparticles."

Cons
news-medical.net - Zinc Oxide can potentially cause cancer
"The chemical, Zinc Oxide, is used to absorb harmful ultra violet light. But when it is turned into nano-sized particles, they are able to enter human cells and may damage the cells' DNA."

lexology.com - consumer expectations and nanomaterials in products
"In April 2014, researchers at the Harvard School of Public Health and Massachusetts In­stitute of Technology released research findings that nanoscale zinc oxide and nanosilver produced statistically significant DNA damage which could lead to genome damage and promote the devel­opment of cancer."

viralglobalnews.com - Sunscreen Efficacy and Safety Questioned by Studies
"Containing nanoparticles of zinc oxide or titanium dioxide, the researchers also suggest the sprays present problems with chemical-inhalation. Although these chemicals are essential constituents of sunscreen, they can pose health risks to those who inhale them. These nanoparticles can cause allergies when inhaled, and are known to have carcinogenic properties."

nownews.seoul.co.kr - “선크림, 피부세포 파괴할 수 있다” 충격 결과
"미국 미주리주립대학 연구팀은 선크림에 주로 함유돼 있는 산화아연(Zinc oxide)성분이 햇볕에 노출되면 활성산소 분자가 방출되는데, 이 과정에서 세포 파괴가 일어날 수 있다고 주장했다."

sciencedaily.com - Sunscreen ingredient may increase skin cancer risk
"zinc oxide nano-particles in the solution absorb the UV rays, the reaction releases electrons, which in turn may produce unstable free radical molecules in the zinc oxide solution."