Comparative study on the acute pulmonary toxicity induced by 3 and 20nm TiO(2) primary particles in mice.

The acute pulmonary toxicity induced by 3-nm TiO(2) primary particles was preliminary investigated after they were intratracheally instilled at doses of 0.4, 4 and 40mg/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 TiO(2) primary particles was performed using the same method. It was found that the 3-nm TiO(2) primary particles induced no pulmonary toxicity at dose of 0.4mg/kg, moderate toxicity at 4mg/kg and lung overload at 40mg/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 TiO(2) particles, their pH values in medium, other than particle size, surface area and aggregation, may play important role in affecting their pulmonary toxicity.