[Genotoxicity of organic bentonite particles in vitro].
OBJECTIVE
To study the genotoxicity induced by organic bentonite particles in vitro.


METHODS
Human B lymphoblast cells (HMy2.CIR) were exposed to organic bentonite particles at the doses of 0, 1.88, 3.75, 7.50 and 15.00 µg/ml for 24, 48 and 72 h, calcium sulfate (30 µg/ml) and SiO2 (30 and 240 µg/ml) served as negative and positive controls, respectively. The genotoxicity of organic bentonite particles and soluble fraction was detected using comet assay and Cytokinesis-block micronucleus (CBMN) assay.


RESULTS
The results of comet assay indicated that % tail DNA increased with the exposure doses and time in organic bentonite group, % tail DNA at the dose of 15.00 µg/ml for 24 h, 48 h and 72 h in organic bentonite group were 3.20 ± 0.19, 4.63 ± 0.88 and 9.49 ± 1.31 respectively which were significantly higher than those in calcium sulfate group (1.40 ± 0.11, 1.37 ± 0.22 and 0.90 ± 0.16) and those in 30 µg/ml SiO2 group (1.83 ± 0.21, 1.41 ± 0.27 and 2.48 ± 0.25) (P < 0.01). The results of CBMN assay showed that micronucleus frequencies (MNF) in organic bentonite group (except for 1.88 µg/ml for 24 h) were significantly higher than those in 30 µg/ml calcium sulfate group (MNF for 24, 48 and 72 h were 1.33‰ ± 0.58‰, 1.33‰ ± 1.15‰ and 1.33‰ ± 0.58‰) and those in 30 µg/ml SiO2 group (2.00‰ ± 0.00‰, 1.68‰ ± 0.58‰ and 2.33‰ ± 0.58‰) (P < 0.01). The results of two assays demonstrated that the soluble fraction of organic bentonite did not induce the genotoxicity.


CONCLUSIONS
The organic bentonite dusts can induce the genotoxicity in vitro, which may be from the particle fraction.
Institute of Environmental Medicine, Medical College, Zhejiang University, Hangzhou 310058, China.
Xiao-Xue
XX
Li
Mei-Bian
MB
Zhang
Ye-Zhen
YZ
Lu
Song-Xue
SX
Yan
Qing
Q
Chen
Ming-Luan
ML
Xing
Hua
H
Zou
Shi-Jie
SJ
Chen
Ji-Liang
JL
He
D001546:Bentonite / Q000633:toxicity*; D002478:Cells, Cultured; D020552:Comet Assay; D004249:DNA Damage; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects*; D015162:Micronucleus Tests; D009152:Mutagenicity Tests; D011791:Quartz / Q000633:toxicity
D001546:Bentonite; D011791:Quartz