2. Barite calcination method A solution of barium sulfide is prepared. The sulfuric acid and zinc oxide are reacted, purified by adding potassium permanganate and zinc powder, and compressed to obtain a zinc sulfate solution. Then, the prepared barium sulfide solution is mixed and subjected to a metathesis reaction to obtain a mixture of zinc sulfide and barium sulfate, and then the precipitate is subjected to pressure filtration, calcination, wet grinding, drying, and pulverization to obtain a zinc white product.

On the other hand, the U.S. Food and Drug Administration (FDA) in their Final Administrative Order on Sunscreen Drug Products posted in September 2021 still accepts titanium dioxide up to 25% in the list of Generally Recognized As Safe and Effective (GRASE) in the main document, without further clarification on what kind or size of particles [9]. However, on page 24 (Sunscreen containing nanomaterials) FDA clearly “distinguish nanomaterials from other forms of these ingredients'' (zinc oxide and titanium dioxide) and ask for comments on “any particular nanomaterials that you believe should not be permitted for use in OTC sunscreen products”. To the best of our knowledge, this Agency did not ban the use of nanoparticulate titanium dioxide in any form, even though it is mentioned on page 34 that the anatase form is the more photoactive one, due to the lack of evidence with real sunscreens OTC (over the counter) in vivo. Moreover, other regulations in Latin America (MERCOSUR agreement, 2006) do not state clearly their position on the use of nanoparticulate TiO₂NPs [10].

Total Zinc (as ZnS)

A safety review conducted by the EFSA in 2021 assessed thousands of studies published on titanium dioxide.

Method of producing improved lithopone

Neutral White, 26 per cent zinc sulphide, 66 per cent barium sulphate, 5 per cent infusorial earth, 3 per cent whiting.

Très apprécié dans le travail des Icônes pour éclaircir, mais également pour les vernis, émaux, peintures, plastique et papier. A l'inverse, ne pas utiliser ce produit dans les applications cosmétiques, comme additif alimentaire ou comme additif médicamenteux.

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].

The ROS seemed to be endlessly produced by P25TiO₂NPs upon irradiation, since the values detected after 6 h are similar to the ones after 3 h. However, the amount of vitamin B2 in the surface of the NPs proved to be enough to decrease the ROS detected even after 6 h. Statistical analysis showed a significant difference between C and A. p < 0.05

Titanium dioxide is used a food colour (E171) and, as with all food colours, its technological function is to make food more visually appealing, to give colour to food that would otherwise be colourless, or to restore the original appearance of food. Titanium dioxide is also present in cosmetics, paints, and medicines.

On November 23, 2022, the General Court of the European Union reversed the conclusion that titanium dioxide was carcinogenic and released a statement (1,2):

“First, the Commission made a manifest error in its assessment of the reliability and acceptability of the study on which the classification was based and, second, it infringed the criterion according to which that classification can relate only to a substance that has the intrinsic property to cause cancer.”
 
As part of our mission at CRIS we base our safety assessments on the currently available scientific evidence and consider many variables (e.g., study quality, journal of publication, etc.), even if it goes against previous conclusions. Evidence-informed decisions making is critical to ensure that the laws and regulations put into place are for the benefit of the population.
 
The EU General Court maintains that the scientific evidence presented wasn’t the complete picture for the ingredient, “in the present case, the requirement to base the classification of a carcinogenic substance on reliable and acceptable studies was not satisfied.”