The trend in the production of NPs is likely to lead to increasing amounts of nano-powders in the air, water and soil, which will consequently affect living organisms. Labielle et al. demonstrated that 25 % of Al(OH)3-coated TiO2 particles from sunscreens are dispersed as a stable colloid and become available to microorganisms and filter-feeders, while the remaining 75 % are probably incorporated into geogenic sediments, where they could become available to benthic fauna. Solar UV iradiation may penetrate as far as 20 m in the water column and therefore photo-activate the dispersed particles, which may have an adverse effect on various aquatic organisms.
In order to achieve the same solids content, the larger filler and the binder should be reduced if necessary.
Fig. 3. Cell survival measured on samples of MSSA with bare and functionalized P25TiO2NPs after 6 h of irradiation. A: P25TiO2NPs, B:vitaminB2@P25TiO2NPs, C: vitaminC@P25TiO2NPs in concentrations of 0.2 μg/mL (red) and 0.2 mg/mL (blue). p <0.05.
In a 2019 study published in the journal Nanotoxicology, researchers recreated the first phase of digestion in mice and fed them titanium dioxide, then examined whether accumulation occurred in the organs. Researchers wrote: “Significant accumulation of titanium was observed in the liver and intestine of E171-fed mice; in the latter a threefold increase in the number of TiO2 particles was also measured. Titanium accumulation in the liver was associated with necroinflammatory foci containing tissue monocytes/macrophages. Three days after the last dose, increased superoxide production and inflammation were observed in the stomach and intestine. Overall, [this] indicates that the risk for human health associated with dietary exposure to E171 needs to be carefully considered.”
Hemolysis was studied on suspensions of P25TiO2NPs (0.2 mg/mL and 0.02 mg/mL), vitaminB2@P25TiO2NPs (0.2 mg/mL and 0.02 mg/mL) and vitamin B2 (0.2 mg/mL and 0.02 mg/mL) were prepared and mixed with 500 μL of anticoagulated blood (donated by Laboratorio de Hemoderivados, UNC) in a rate of 1/10. A solution of NaCl 10% was used as the positive control and PBS as the negative control. Then, the samples were irradiated using the LED described above for 3 and 6 h to simulate the light penetration into the skin. Also, a set of samples was kept in the dark as control. Finally, the samples were centrifuged and the absorbance at 540 nm was measured in the supernatants. The experiment was reproduced twice; the standard deviation was calculated and p-value < 0.05 were considered significant.