Reproductive and developmental toxicity screening test of new TiO2 GST in Sprague-Dawley rats.

TiO2 nanoparticles are widely used in paints, plastics, cosmetics, printing ink, rubber, food products, pharmaceuticals and other products (photocatalyst, etc.). However, there is little toxicological information during reproduction and developmental period. This study was performed to obtain safety data for new TiO2 powder, GST (Green Sludge Titanium) produced through sludge recycling of the sewage treatment plant for Reproduction/developmental toxicity screening test in Sprague-Dawley (SD) rats in according to the OECD test guideline (TG 421). Based on the results of the dose-range finding study (14-day repeated toxicity), GST was orally administered to rats at doses of 0, 500, 1000, and 2000 mg/kg B.W/day. Males were dosed for 35 days beginning 14 days before mating, and females for a maximum of 53 days beginning 14 days before mating to day 13 of lactation, including throughout the mating, gestation and lactation periods. In the reproductive and developmental examinations, there were no marked toxicities in terms of general clinical signs, body weight, food consumption, organ weights, macroscopic / microscopic findings, stages of spermatogenesis in the testis, reproductive finding (estrous cycle, copulation-fertility-gestation index), developmental finding (number of corpora lutea and implantations, pups parameters including live birth and viability index). The NOAEL for reproductive/developmental screening toxicity was concluded to be 2000 mg/kg/day under the present study conditions.

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

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.

Repeated-dose 90-day oral toxicity study of GST in Sprague-Dawley rats.

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.

Evaluation of potential eye or skin irritation/corrosion in rabbit exposed to TiO2 photocatalyst (GST).

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).

In vitro acute inhalation toxicity for TiO2 (GST) using 3D human tissue model (EpiAirwayTM).

The present study was performed to screen in vitro potential acute inhalation toxicity using an EpiAirwayTM tissue model (human tracheal/bronchial tissue) for the nano-sized titanium dioxide, GST manufactured as a photocatalyst through of sludge recycling and to compare with P-25 a commercialized photocatalytic material. According to the protocol provided by in vitro tissue manufacturer, the GST was exposure to the tissue for 3 hours in 450, 500, 650, 850 mg/mL concentration after preliminary dose range finding study and then tissue viability (%, IC75) was calculated using the MTT assay. Besides, the histopathological observation was performed to compare to the MTT assay. As a result of study, IC75 could not be confirmed at 850 mg/mL in both GST and P-25 and the grade was confirmed to be IC75> 600 mg/mL in vitro model tissue category. Therefore, it was considered that the GHS category could be classified as 'No classification' in screening method for potential acute inhalation toxicity. Also, not the morphological effects of epithelial cells in tissue model were observed compared with the vehicle control and histological findings were similar to the results of MTT Viability assay. Based on these results, the potential acute inhalation toxicity for GST produced through sludge recycling using in vitro tissue model inhalation toxicity showed that it could be non-hazardous substance. However, further study (in vivo study, etc.) is thought to be needed to ascertain whether GST is a toxic effect or safe.

Acute toxicity assessment for TiO2 photocatalyst (GST) made from wastewater using TiCl4 in rat.

TiO2 was a photocatalyst that used to the most common product because of the high efficiency. TiO2 (P-25, commercial nanomaterial product) is the most typical photocatalyst product and TiO2 (GST) was a sludge recycling product. This study was reported to evaluate an acute toxicity of TiO2 (P-25 and GST) according to OECD test guideline 402 and 423 in Sprague-Dawley (SD) female rats via route of oral and dermal. There was investigated the lethal dose (LD50), and mortality, clinical signs, body weight changes and gross findings were continually monitored for 14 days following the single administration. After administration, TiO2 (P-25) was calculated that LD50 was considered to be a dose of over 2000 mg/kg body weight for both different route of exposure, and TiO2 (GST) was the same. Other items were no observed an adverse effect between P-25 and GST; no mortality and clinical signs, accidental body weight loss, no gross findings. On the basis of the above results, the toxicity of the GST was almost equal to that of the commercial product, P-25 and there was no toxicological evidence.