Lithopone was developed in the 1870s as a substitute for lead carbonate (lead white), to overcome its drawbacks of toxicity and poor weathering resistance. Within a few years, titanium dioxide displaced lithopone to become the white pigment (PW6) par excellence in the industry and the world’s best-selling inorganic pigment. However, titanium is a product whose price is subject to large price variations due to product availability. These price increases affect the competitiveness of finished products, and so the search for an alternative to titanium dioxide has generated a variety of possibilities to optimise its use. 

In an early study Jani et al. administred rutile TiO₂ (500 nm) as a 0.1 ml of 2.5 % w/v suspension (12.5 mg/kg BW) to female Sprague Dawley rats, by oral gavage daily for 10 days and detected presence of particles in all the major gut associated lymphoid tissue as well as in distant organs such as the liver, spleen, lung and peritoneal tissue, but not in heart and kidney. The distribution and toxicity of nano- (25 nm, 80 nm) and submicron-sized (155 nm) TiO₂ particles were evaluated in mice administered a large, single, oral dosing (5 g/kg BW) by gavage. In the animals that were sacrificed two weeks later, ICP-MS analysis showed that the particles were retained mainly in liver, spleen, kidney, and lung tissues, indicating that they can be transported to other tissues and organs after uptake by the gastrointestinal tract. Interestingly, although an extremely high dose was administrated, no acute toxicity was observed. In groups exposed to 80 nm and 155 nm particles, histopathological changes were observed in the liver, kidney and in the brain. The biochemical serum parameters also indicated liver, kidney and cardiovascular damage and were higher in mice treated with nano-sized (25 or 80 nm) TiO₂ compared to submicron-sized (155 nm) TiO₂. However, the main weaknesses of this study are the use of extremely high single dose and insufficient characterisation of the particles.

Barium sulphate is typically described as a white, odorless powder. This white coloration is due to its crystalline structure and the arrangement of Ba^2+ and SO₄^2− ions within the compound. The brightness and consistency of this white powder are crucial for its use in various applications. For instance, in the pharmaceutical industry, barium sulphate is used as a radiopaque agent in X-ray imaging of the gastrointestinal tract. In this context, its purity and the absence of color impurities are vital for ensuring accurate imaging results.

Nanotoxicology 

The presence of so many lithopone factories in China has also led to advancements in production technology and quality control. Chinese manufacturers have invested heavily in research and development to improve the performance of their lithopone products, leading to higher quality and more consistent products on the market. This has helped to cement China's reputation as a leading producer of lithopone on the global stage.

Near sample

Titanium dioxide goes into many industrial and consumer products. It makes paper white and bright, it keeps plastics and rubber soft and flexible, and helps remove harmful emissions from car exhaust, among many other uses. In the drug industry, it's a key ingredient in pill capsules and tablet coatings to keep the medicine inside from being affected by sunlight.