Drobne et al. used the terrestrial arthropod Porcellio scaber as a test organism for determining the cytotoxic effect of TiO₂ NPs (anatase). The animals were exposed to TiO₂ NPs of two different sizes (25 nm and 75 nm) in the concentration range 10–1000 μg TiO₂/g dry food for 3 to 14 days. No adverse effects, such as mortality, body weight changes or reduced feeding, were observed. In fact, quite the opposite, an enhanced feeding rate, food absorption efficiency and increase in catalase activity were observed. The intensity of these responses appeared to be time- but not dose-dependent. It should also be noted that the concentrations tested in this study were much higher than the predicted concentration (4.8 μg/g soil) at high emission scenario of nano-sized TiO₂. Using the same test organism another group showed that exposure to TiO₂ NPs induced destabilization of cell membrane in the epithelium of digestive glands isolated from exposed animals. They also showed that this effect can be observed after just 30 minutes of exposure.

The alarming fact of this study is that it was only conducted for 100 days, I have been wearing makeup daily for at least the last fifteen years & would have eaten kilo's of lipstick in my life time - what effects has this had on my system & health??

Reacting to the report, France’s ministers of health, agriculture and economy instructed the country’s food health and safety agency, Anses, to investigate whether the additive poses a risk for human health.

The study was said to be prompted by “growing concerns that daily oral… Intake is associated with an increased risk of chronic intestinal inflammation and carcinogenesis”, or cancer formation”.

In its statement to USA TODAY, the FDA maintained that, in all post-approvals for food additives, our scientists continue to review relevant new information to determine whether there are safety questions and whether the use of such substance is no longer safe under the Federal Food, Drug, and Cosmetic Act.

It's all over the place in our environment, said Dr. Johnson-Arbor.

Titanium dioxide (TiO₂) is considered as an inert and safe material and has been used in many applications for decades. However, with the development of nanotechnologies TiO₂ nanoparticles, with numerous novel and useful properties, are increasingly manufactured and used. Therefore increased human and environmental exposure can be expected, which has put TiO₂ nanoparticles under toxicological scrutiny. Mechanistic toxicological studies show that TiO₂ nanoparticles predominantly cause adverse effects via induction of oxidative stress resulting in cell damage, genotoxicity, inflammation, immune response etc. The extent and type of damage strongly depends on physical and chemical characteristics of TiO₂ nanoparticles, which govern their bioavailability and reactivity. Based on the experimental evidence from animal inhalation studies TiO₂ nanoparticles are classified as “possible carcinogenic to humans” by the International Agency for Research on Cancer and as occupational carcinogen by the National Institute for Occupational Safety and Health. The studies on dermal exposure to TiO₂ nanoparticles, which is in humans substantial through the use of sunscreens, generally indicate negligible transdermal penetration; however data are needed on long-term exposure and potential adverse effects of photo-oxidation products. Although TiO₂ is permitted as an additive (E171) in food and pharmaceutical products we do not have reliable data on its absorption, distribution, excretion and toxicity on oral exposure. TiO₂ may also enter environment, and while it exerts low acute toxicity to aquatic organisms, upon long-term exposure it induces a range of sub-lethal effects.