Evaluation of in vitro toxic effects of cement dusts: a preliminary study

Cement is widely used for construction and several reports have suggested a potential toxicity of cement dusts although it has never been definitively assessed. To determine the cytotoxic and bioactive effects of cement dusts, cultures of normal rat fibroblasts were exposed to different types of cements and cell growth parameters, apoptosis and the occurrence of DNA damage (both in terms of DNA breaks and oxidative damage) were analyzed. Cells were exposed to cement extracts or cultured in direct contact with cement dusts and the results obtained were compared to cells cultured in fresh medium. A dose-dependent decrease in viable cells was observed with all tested cements. Different results were obtained in the cell-cement direct contact tests compared to the indirect contact tests performed using extracts. Inhibition of cell growth was associated in most cases with an accumulation of cells in the S-phase of the cell-cycle and the appearance of an apoptotic peak. DNA strand breaks, assessed by comet test, and increase in the levels of 8-OHdG, an important marker of DNA oxidative damage, always occurred by incubating cells in the presence of cement extracts or dusts. However, after removal of cement, a rapid damage repair was generally observed with an almost complete recovery within 12 hours. In conclusion, all cements analyzed in this study displayed a limited toxicity in vitro without significant differences amongst them. Overall, the results obtained indicate that cements should be treated as hazardous materials but they do not allow to make accurate predictions regarding the in vivo effects. Further studies are warranted to reach a better understanding of the potential toxic effects of cements, to identify the responsible mechanisms and to evaluate the possibility of modulating and/ or preventing them.