In Vitro Study On Genotoxicity Of Chrysotile And Its Artificial Substitutes

Objective：Chrysotile and its substitute，due to its unique propertiesof strong intensity and high temperature tolerance，is important raw materialin textile industry, building industry, chemical industry and machinery. It iswidely used in various fields, existed everywhere in our life. Generallyaccepted genotoxicity of chrysotile and its substitutes in different region havenot come to scientific conclusions, which was considered as the basis ofgenetic effects and one of the important occasions in the development ofmalignant tumors. Therefore, the study on the genotoxicity of chrysotile andits substitutes is necessary. On the basis of previous studies, this paper aims toexplore the genetic toxicity of chrysotile and its substitutes. Methods：(1)Chrysotile from Axel，Mangai，Xinkang Sichuan，Southern Shanxi andsubstitutes glass fiber, ceramic fiber, rockwool fiber were formulated to dustsuspensions at three different density of50μg/ml,100μg/ml and200μg/ml.Chinese hamster lung cells (V79cells) were exposed to those suspensions for24h,48h,72h respectively. The comet assay was used to detect DNAdamage.(2) Chrysotile from Axel，Mangai，Xinkang Sichuan，Southern Shanxiand substitutes glass fiber, ceramic fiber, rockwool fiber were formulated todust suspensions at three different density of50μg/ml,100μg/ml and200μg/ml. Chinese hamster lung cells (V79) cells were exposed to thoseSuspensions respectively. Micronucleus assay was used to detect chromosome damage. Results：(1)Compared to negative control groups, the comet assayshowed that the DNA migration Distance, OTM and tailing rate in Chrysotilefrom Axel，Mangai，Xinkang Sichuan，Southern Shanxi and substitutes glassfiber, ceramic fiber, rockwool fiber dust suspensions at three different densityof50μg/ml,100μg/ml and200μg/ml were all statistically significant (P＜0.05). The DNA migration Distance, OTM and tailing rate increased graduallywith increasing concentration in a dose-dependent manner (P＜0.05).（2）DNA migration Distance, OTM and tailing rate of V79cells exposed tochrysotile dust suspensions from Axel，Mangai，Xinkang Sichuan，SouthernShanxi and substitutes glass fiber, ceramic fiber, rockwool fiber for48hourswere increased significantly comparing to the24hour group in the same doseand species(P＜0.05).However，compared to48h group，DNA migrationDistance, OTM and tailing rate of V79cells exposed to the seven species wereall decreased significantly in the72h group(P＜0.05).(3) Compared tonegative control groups, the Micronucleus assay showed that the micronucleusrate in Chrysotile from Axel，Mangai，Xinkang Sichuan，Southern Shanxi andsubstitutes glass fiber, ceramic fiber, rockwool fiber dust suspensions at thedensity of100μg/ml and200μg/ml were all statistically significant (P＜0.05).The micronucleus rate increased gradually with increasing concentrationin a dose-dependent manner (P＜0.05). Compared to negative control groups,the Micronucleus assay showed that the micronucleus rate in Chrysotile fromAxel，Mangai，Xinkang Sichuan，Southern Shanxi and substitutes glass fiber, ceramic fiber, rockwool fiber dust suspensions at the density of50μg/ml werenot significantly different(P＞0.05).Conclusions：(1) chrysotile and threesubstitutes are genotoxic, which damage cells by acting on the mechanism ofDNA, so DNA single-strand or double-strand breaks occur; may also act onthe chromosome, so that the occurrence of chromosome or chromatid fracture,deletions, inversions, so as to cause chromosomal aberrations. chrysotile andsubstitute security are worth further studying.(2) three substitutes andchrysotile-induced dose-dependent DNA damage exists, and with prolongedexposure aggravated damage, damage repair mechanisms may existsimultaneously.(3)three kinds of substitutes and chrysotile-inducedchromosomal aberrations in a dose-dependent manner.