Comparable DNA and chromosome damage in Chinese hamster ovary cells by chlorohydroxyfuranones

Abstract

Chlorinated drinking water contains several chlorohydroxyfuranone (CHF) by-products whose contribution to cancer risk is not presently known. 3,4-Dichloro-5-hydroxy-2(5H)-furanone (MCA), 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF), and 3- chloro-4-methyl-5-hydroxy-2(5H)-furanone (MCF) were studied for the induction of DNA damage, using the alkaline single-cell gel (SCG)/comet assay, and for chromosome damage, using sister-chromatid exchange (SCE) and chromosome aberration (CA) tests, in Chinese hamster ovary (CHO) cells. 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), the known genotoxic chlorination by-product and a rat carcinogen, was used as a reference chemical. The SCG analyses were done using concentrations that caused little or no cytotoxicity compared to that of the concurrent control cultures. In the cytogenetic tests, the CHFs were tested up to maximum cytotoxicity. MX and MCA were the most cytotoxic of the compounds in CHO cells followed by CMCF and MCF. All of the CHFs induced DNA damage, SCEs and CAs (mainly chromatid-type breaks and exchanges) in a concentration-related manner, with the exception that MCA was a weak inducer of SCEs. There were no significant differences between the lowest concentration of MX, MCA, and CMCF to cause DNA damage (SCG assay). Based on comparisons of the slopes of regression lines, MX was somewhat more potent than either MCA or CMCF, and MCF was clearly less potent than the other three compounds in the assay. The order of potency was MX > CMCF > MCA > MCF in inducing SCEs and MX > MCA > CMCF > MCF in inducing CAs. The data show that there are differences in the potency of genotoxicity among the CHFs tested. In many cases, however, the extent of maximum effect observed was comparable between the compounds. The results suggest that besides MX other CHFs should be considered in the evaluation of genotoxic risks associated with the consumption of chlorinated drinking water.

Genotoxicity analysis of two hydroxyfuranones, byproducts of water disinfection, in human cells treated in vitro

“…These findings agree with the results reported by Mäki-Paakkanen et al [2001] in CHO cells. In both studies, MCA showed a dose-dependent effect, from 5 lg/mL (29.6 lM) in CHO cells, and from 50 lM in TK6 cells (the lowest concentration tested).…”

“…In both studies, MCA showed a dose-dependent effect, from 5 lg/mL (29.6 lM) in CHO cells, and from 50 lM in TK6 cells (the lowest concentration tested). According to these results, and from other studies that demonstrated the ability of MCA to induce sister chromatid exchanges, chromosome aberrations, and duodenal nuclear anomalies of B6C3F1 mice [Daniel et al, 1991;Mäki Paakkanen et al, 2001], it can be stated that MCA is a genotoxic agent with clastogenic activity.…”

Effects of chlorohydroxyfuranones on 3-methylcholanthrene-induced neoplastic transformation in the two-stage transformation assay in C3H�10T1/2 cells

“…This order of potency agrees well with their genotoxic potential in mammalian cells in vitro. MX and CMCF are rather similar but MCF is less potent in those assays (Le Curieux et al 1999;Ma¨ki-Paakkanen et al 2001). A decrease in the degree of chlorination of the methyl group at the 4-position decreased their potency.…”

Bacterial and mammalian‐cell genotoxicity of mixtures of chlorohydroxyfuranones, by‐products of water chlorination

“…The data on the induction of gene mutations in bacteria and in mammalian cells, and on the induction of DNA and chromosome damage in mammalian cells by the CHFs, show that there are differences in the genotoxic potency of these chemicals [Meier et al, 1986[Meier et al, , 1987aIshiguro et al, 1988;LaLonde et al, 1990LaLonde et al, , 1991Kronberg and Franzén, 1993;Niittykoski et al, 1995;Knasmüller et al, 1996;Franzén et al, 1998;Le Curieux et al, 1999;Shaughnessy et al, 2000;Mäki-Paakkanen et al, 2001a,b]. However, the maximum effect observed in the alkaline Comet assay and the chromosome aberration test with CHO cells was similar for the four compounds [Mäki-Paakkanen et al, 2001a]. The results suggest that CHFs should be considered as a group in the evaluation of the genotoxic risks associated with the consumption of chlorinated drinking water.…”

“…The concentrations of the CHFs tested were based on earlier data obtained in our laboratory [Mäki-Paakkanen et al, 2001a], and were selected to have no effect on the growth of the cells and to give no or only a slight increase in the frequency of structural CAs when tested individually in the assay. Preliminary experiments were performed to establish the CHF mixture concentrations causing from little or no cytotoxicity to maximum cytotoxicity (as determined by a decrease in cell confluency before the harvest and a decrease in cells and metaphases on the slides).…”