Comparative study on the acute pulmonary toxicity induced by 3 and 20 nm TiO2 primary particles in mice

The acute pulmonary toxicity induced by 3-nm TiO2 primary particles was preliminary investigated after they were intratracheally instilled at doses of 0.4, 4 and 40 mg/kg into lungs of mice. The biochemical parameters in bronchoalveolar lavage fluid (BALF) and pathological examination were used as endpoints to assess their pulmonary toxicity at 3-day postexposure. As such, the pulmonary toxicity assessment of 20-nm TiO2 primary particles was performed using the same method. It was found that the 3-nm TiO2 primary particles induced no pulmonary toxicity at dose of 0.4 mg/kg, moderate toxicity at 4 mg/kg and lung overload at 40 mg/kg, and this kind of particles did not produce more pulmonary toxicity than the 20-nm ones at any instilled doses. As regards physicochemical characteristics of the two TiO2 particles, their pH values in medium, other than particle size, surface area and aggregation, may play important role in affecting their pulmonary toxicity.