anatase titanium dioxide(tio2) factories

Although barium sulfate is almost completely inert, zinc sulfide degrades upon exposure to UV light, leading to darkening of the pigment. The severity of this UV reaction is dependent on a combination of two factors; how much zinc sulfide makes up the pigments formulation, and its total accumulated UV exposure. Depending on these factors the pigment itself can vary in shade over time, ranging from pure white all the way to grey or even black. To suppress this effect, a dopant may be used, such as a small amount of cobalt salts, which would be added to the formulation. This process creates cobalt-doped zinc sulfide. The cobalt salts help to stabilize zinc sulfide so it will not have as severe a reaction to UV exposure.

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The lack of clear regulations and controls explains that P25TiO2NPs are still found in many of the commercialized sunscreens in the market. Some of them are coated to reduce the photoactivity of the anatase form, which is known to be responsible for tissue damage, but not enough studies were made on these coated forms. The anatase photoactivity could trigger the production of reactive oxygen species (ROS) generation, as it was stated before. The ROS are chemically reactive species containing oxygen, such as peroxides, superoxide, hydroxyl radical, and singlet oxygen. They are regularly produced in the biological milieu and counterbalanced by physiological antioxidant defense mechanisms. However, an abrupt increase of ROS may result in non-reversible damage to the skin cells. The effects of coated and uncoated P25TiO2NPs need therefore to be studied, and articles on this topic present different conclusions. [11][12][13] Recent literature on this topic found that TiO2NPs inhalation provokes serious genotoxicity and DNA damage [14][15][16][17]. On the other hand, some studies in rats have reported no significant harm to genetic material [18][19][20][21][22].

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