Repeated-dose 28-day dermal toxicity study of TiO2 catalyst (GST) in Sprague-Dawley rats

Abstract

TiO2 have been studied on inhalation and skin exposure due to the properties of the materials' use (cosmetics, paints and other products) and the additional safety information on other intake routes for the potential risk assessment is limited. The aim of this study was to obtain dose-range for subchronic study (repeated 90-day dermal toxicity) new TiO2 powder, GST produced through sludge recycling of the sewage treatment plant through repeated-dose toxicity in Sprague-Dawley (SD) rats. Three test groups for the GST were administered at 500, 1000, 2000 mg/kg B.W/day in addition to a control group (distilled water for injection). 5 male and 5 female rats were included in each group, and we examined the clinical signs, body weights, food consumption, necropsy (organ weights, macroscopic findings), hematological / biochemical parameters and histopathological findings (eye, skin). As a result of observations, there were no treatment-related effects including clinical signs, mortality, necropsy findings etc. Therefore, the present results suggest that the TiO2-related effects were not observed for dermal during 28-day and dose selection for repeated 90-day study was considered to be 500, 1000 and 2000 mg/kg B.W/day under the present study conditions.

Keywords: GST; NOAEL; TiO2; repeated-dose toxicity.

Figure 1

Characterization of TiO₂ particles (GST) analyzed by Korea TECH: (a) negative zeta potential (−35.4±5.99 mV, 30 mg/mL); (b) size distribution by intensity (mean: 336.8 nm).

Figure 2

Characterization of TiO₂ particles (GST): (a) SEM (scanning electron microscope) image analyzed by KRICT.

Figure 3

Characterization of TiO₂ particles (GST): (a) A particles dispersed in 99.9% EtOH was deposited on a copper grid and analyzed using TEM (Transmission electron microscope) image by Korea Basic Science Institute; (b) Size distribution (95.8±46.3 nm, 46–270 nm,) of the imaged GST(image J software).

Figure 4

Changes for body weight and food consumptions: (a) body weight (male); (b) Body weight (female); (c) Food consumptions (male); (d) food consumptions (female).

Figure 5

Eye photographs (Left: Slide scanner image, ZEISS Axio Scan. Z1, right: Optical microscope, X50) including the cornea, iris, lens, retina and accessory organs (optic nerve, harderian gland): (a) Control group (animal number 2101); (b) High dose group (animal number 2405).

Figure 6

Skin photographs (Left: Slide scanner image, ZEISS Axio Scan. Z1, right: Optical microscope, X50) including the epidermis and dermis: (a) Control group (animal number 2101); (b) High dose group (animal number 2405).