[Study of toxicity to rats induced by nanosized SiO2 and standard SiO2].
OBJECTIVE
To study the pulmonary toxicity to rats induced by the nanosized SiO(2) or the standard SiO(2).


METHODS
Seventy-two male SD rats were divided into three groups: the nanosized SiO(2) group, the standard SiO(2) group and the control group. 24 rats each group. The nanosized SiO(2) group and the standard SiO(2) group were instilled intratracheally with 0.5 ml suspension of 0.6 mg/ml nanosized SiO(2) or standard SiO(2) respectively while the control group was instilled with 0.5 ml physiological saline. On the 3rd, 7th, 14th, and 28th day after exposure, six rats were sacrificed at each time point and the total white cells counts and total protein in BALF and the histopathological changes were observed. The pulmonary toxicities of the two SiO(2) dusts were compared.


RESULTS
Nanosized SiO(2) caused significant increase at 3rd, 7th, 14th day after the exposure [(16.0 +/- 6.0) x 10(6), (11.1 +/- 4.0) x 10(6), (12.2 +/- 4.6) x 10(6)] compared with saline (P < 0.05 or P < 0.01) in the total numbers of white cells and on the 3rd after the exposure compared with standard SiO(2) [(5.7 +/- 3.7) x 10(6), P < 0.01]. Meanwhile, Nanosized SiO(2) significantly increased the total protein on the 14th, 28th day after the exposure (0.41 +/- 0.14, 0.41 +/- 0.19 g/L) compared with saline or standard SiO(2) and nanosized SiO(2) on the 3rd, 7th day after the exposure (P < 0.05 or P < 0.01). Nanosized SiO(2)-treated rats showed marked white cell infiltration in alveolar space or around brondum the blood vessel. Standard SiO(2) caused similar but less severe responses compared with nanosized SiO(2). Van Gieson's-stained sections showed no significant fibrosis in these dust-exposed rats at 28th day after the exposure.


CONCLUSIONS
Nanosized SiO(2) can cause severer and longer pulmonary toxicity in rats than standard SiO(2). The pulmonary particle load threshold of nanosized SiO(2) may be lower than that of standard SiO(2).
Ying
Xingqiu
X
Department of Toxicology, School of Medicine, Zhejiang University, Hangzhou, China.
Zheng
Yi-Fan
YF
Zhu
Hui-Juan
HJ
Jin
Jing
J
Zeng
Qun-Li
QL
Zhang
Qun-Wei
QW
Zhu
Xin-Qiang
XQ
D000818:Animals; D008297:Male; D053758:Nanoparticles / Q000633:toxicity*; D010316:Particle Size; D011658:Pulmonary Fibrosis / Q000139:chemically induced*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012822:Silicon Dioxide / Q000633:toxicity*
D012822:Silicon Dioxide