TiO2 NPs photocatalyst is widely used in a variety of applications and products in the environmental and energy fields, including self-cleaning surfaces, air and water purification systems, sterilization, hydrogen evolution, and photoelectrochemical conversion. The possible biological and safety effects of TiO2 dermal exposure and absorption have not been well studied and more investigations on the potential health hazards of the TiO2 are needed. This study aimed to investigate potential effect of local lesions (eye and skin irritation/corrosion) for new TiO2 material powder, GST produced through sludge recycling of the sewage treatment plant in according to the OECD test guideline (TG 404, 405) and imaging evaluation (micro-computed tomography analysis), histopathology examination. Also, P-25, commercial photocatalyst was used to compare with GST. For the eye or skin irritation/corrosion test, the test substances (GST, P-25) showed no irritation/corrosion for local lesions and the GHS category was identified as a “No hazard class”. The imaging analysis indicated that GST did not penetrate or distribute in the local lesions (eye, skin) and the treatment-related effect was not observed in histopathology. Therefore, the present study revealed that new TiO2 powder, GST was considered to be no potential effects (irritation/corrosion), penetration or distribution in the local lesions (eye, skin).

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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. Therefore, the aim of this study was to obtain safety data for new TiO2 powder, GST produced through sludge recycling of the sewage treatment plant through repeated-dose toxicity in Sprague-Dawley (SD) rats in according to the OECD test guideline (TG 408). Based on the results of the dose-range finding study (28-day repeated toxicity), GST was orally administered to rats at doses of 0, 500, 1000, and 2000 mg/kg B.W/day for 90-day and reversibility of effects of 2000 mg/kg bw/day was assessed after 4 weeks. In clinical signs, compound-colored stool was observed in all animals of treatment group (low: day 14 or 15, middle: day 8, high: day 8) and continuously observed up to the end of administration or day 1 of recovery period (high dose group). Also, the test substance retention in gastro-intestinal tract was observed in all animals of treatment group in gross finding at necropsy and foreign materials in lumen of these organs (stomach, duodenum, ileum, cecum, colon, rectum) likely indicative for the presence of test material in histopathological examination. In addition, no test substance-related adverse effects were noted in the detailed clinical observations, sensory reactivity/ functional assessments, body weight, food consumption, urinary analysis, ophthalmological examination, hematological / biochemical parameters, organ weights, histopathological findings. Therefore, the present results show that the NOAEL (no observed adverse effect level) of new TiO2 powder, GST was considered to be 2000 mg/kg B.W/day in rats after repeated oral administration for 90-day under the present study conditions and no target organs were identified.