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Chlorohydroxyfuranones (CHFs) are mutagenic disinfection by-products found in chlorine-treated drinking water. In the current study, the genotoxicity of four CHFs, 3,4-dichloro-5-hydroxy-2(5H)-furanone (MCA), 3-chloro-4-methyl-5-hydroxy-2(5H)-furanone (MCF), 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF) and 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), was determined. Two in vitro assays, the microscale micronucleus assay on L5178Y mouse lymphoma cells and the unscheduled DNA synthesis assay on a hepatocyte primary culture from Fisher F344 rats, were carried out. All four CHFs demonstrated genotoxic effects in both assays. In the two systems used, CMCF was the most genotoxic compound, followed by MCA, MX and MCF, respectively. This work was the first study of the DNA damaging properties of all four CHFs in two in vitro genotoxicity tests. These new data expand the range of genetic damages induced by this group of compounds.

New developments in mutagenic risk assessment have appeared in the past few years. New methods have been developed such as in vitro micronucleus assay for chromosomal alterations, comet assay for primary DNA damage, use of transgenic animals to detect in vivo gene mutations, and fluorescent in situ hybridization method to detect aneuploidy. Other new methods will be developed in the few next years, including the use of DNA chips and the use of molecular biological methods. Several micromethods have been developed to test a great number of chemical compounds. New concepts have appeared concerning interpretation of data, and particularly of thresholds especially in the case of aneugens; in some cases metabolic or mechanistic thresholds were demonstrated. Genotoxic studies are best integrated into toxicological testing: for example, some genotoxicity tests can be integrated into subacute toxicology; interpretation of data includes metabolism; and toxicokinetic data relate to other toxicological studies. Conversely, genotoxicity data can be used to interpret toxicology studies.

A micromethod for the in vitro micronucleus assay was developed using L5178Y cells to enable the rapid screening of a large number of molecules. The method is quick, simple to perform and needs very small amounts of compound, i.e.

Three short-term assays (SOS chromotest, Ames fluctuation test and newt micronucleus test) were performed to detect the genotoxic activity of organohalides, compounds likely to be found in chlorinated and/or ozonated drinking water: monochloro-, dichloro- and trichloroacetic acids and mono-bromo-, dibromo- and tribromoacetic acids. With the SOS chromotest, only three of the chemicals studied (dichloroacetic acid, dibromo- and tribromoacetic acids) were found to induce primary DNA damage in Escherichia coli PQ 37. In the Ames fluctuation test, all the compounds except monochloroacetic acid showed mutagenic activity in Salmonella typhimurium strain TA100. In these two in vitro tests, a good correlation between increasing number of substituents and decreasing mutagenicity was observed. Namely, the toxicity of brominated and chlorinated acetic acids decreased when the number of substituents increased. The newt micronucleus test detected a weak clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae for trichloroacetic acid only.

Three short-term assays (the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test) were carried out to evaluate the genotoxicity of four trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane and bromoform). With the SOS chromotest, all the chemicals studied except chloroform were found to induce primary DNA damage in Escherichia coli PQ37. In the Ames-fluctuation test, only bromoform showed mutagenic activity on Salmonella typhimurium strain TA100. The newt micronucleus assay detected a clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae for bromodichloromethane and bromoform. It appeared that the presence of bromine substituent(s) generally led to significant genotoxic activity. Moreover, the use of the metabolic system significantly increased the genotoxicity of the brominated trihalomethanes in the SOS chromotest. Unlike previous investigations in which the SOS chromotest was always the least interesting assay, this study exhibited the good efficiency of this in vitro test on E.coli for the detection of trihalomethanes with bromine substituents.

Three short-term assays (the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test) were carried out to evaluate the genotoxicity of six halogenated acetonitriles identified in chlorinated waters (monochloro-, dichloro-, trichloro-, monobromo-, dibromo- and bromochloroacetonitrile). With the SOS chromotest, three of the chemicals studied (dichloro-, dibromo- and bromochloroacetonitrile) were found to induce primary DNA damage in Escherichia coli PQ37. In the Ames-fluctuation test, all the compounds except dibromoacetonitrile showed muta- genic activity on Salmonella typhimurium strain TA100. The newt micronucleus assay detected a clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae for all the six haloacetonitriles studied. Moreover, two structure-activity relationships were noted: (l) the genotoxic activity of haloacetonitriles containing bromine substituents appeared higher than the corresponding chlorinated acetonitriles and (2) the clastogenic activity of the chlorinated acetonitriles increased with the number of chlorine substituents.

Three short-term assays (the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test) were carried out to evaluate the genotoxicity of five chlorinated propanones identified in several chlorinated waters (monochloropropanone, 1,1-dichloropropanone, 1,3-dichloropropanone, 1,1,1-trichloropropanone and 1,1,3-trichloropropanone). In the SOS chromotest, all the compounds except monochloropropanone were found to induce primary DNA damage in Escherichia coli. With the fluctuation test, all five chloropropanones showed mutagenic activity on Salmonella typhimurium strain TA100. The newt micronucleus assay detected a clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae only for 1,3-dichloropropanone and 1,1,3-trichloropropanone. Moreover, two structure-activity relationships are noticeable: (1) chloropropanones with chlorine substituents on both carbon positions (1,3-DCP and 1,1,3-TCP) are by far more genotoxic than chloropropanones substituted only on one carbon position (1,1-DCP and 1,1,1-TCP); (2) the increase of the number of chlorine substituents decreases the mutagenic activity (fluctuation test) of the chlorinated propanones studied.

Three short-term assays (the SOS chromotest, the Ames fluctuation test and the newt micronucleus test) were used to evaluate the genotoxicity of seven chemicals (4-nitroquinoline 1-oxide, potassium dichromate, formaldehyde, sodium hypochlorite, benzo[a]pyrene, cyclophosphamide and 2-naphthylamine). In the SOS chromotest, all seven compounds except sodium hypochlorite and cyclophosphamide were found to induce primary DNA damage in E. coli. With the Ames fluctuation test, all seven chemicals except sodium hypochlorite showed mutagenic activity on Salmonella typhimurium TA100, TA102 or TA98. The newt micronucleus assay detected a clastogenic effect of all seven compounds except formaldehyde on the peripheral blood erythrocytes of Pleurodeles waltl larvae. For each compound, the sensitivity of the tests was compared; (1) the SOS chromotest is the least sensitive assay in every case, (2) the Ames fluctuation test is the most sensitive assay for studied chemicals with direct genotoxic effect and (3) the newt micronucleus assay is the most sensitive test for tested compounds with indirect genotoxic activity. The potential contribution of these three tests in the monitoring of water genotoxicity is discussed.

The mutagenicity of trenbolone, a synthetic androgen, was studied in a number of genotoxicity tests using in vitro and in vivo systems for gene mutations, chromosomal mutations and primary DNA damage demonstration. Only 2 tests were found to be positive or dubious: the in vitro micronucleus test in SHE cells (however, this test was negative in 2 other cell lines: C3H and CHO cells) and the Ames test for 1 of the 5 studies which found a positive result in TA 100 strain without metabolic activation. Repetition of this study with pure trenbolone showed no genotoxic activity; trenbolone was therefore considered to be devoid of genotoxic activity.

The search for a mutation prone activity on bacteria must be completed by tests on eucaryotes, in vitro as well as in vivo. Tests on eucaryotes enable to study agents inducing gene mutations [on yeats, cultures of mammal cells (V 79, L 5278 Y), lethal recessive mutation linked to the sex chromosome, on drosophils...], chromosomal mutations (metaphases analysis in vitro and in vivo, micronucleus, lethal dominance), the involvement of repair mechanisms of DNA (non-programmed DNA synthesis, exchange of sister chromatides...). One must well differentiate the tests usable routinely for a screening from the tests currently validated and routine tests. It is only at the completion of a set of tests on bacteria and eucaryotes cells that the potential mutation risk of a product for human health, may be ascertained.

This study reports the short-term effects of fenofibrate in golden Syrian hamsters receiving a standard or cholesterol enriched (0.5%) diet. In chow fed control animals, the plasma cholesterol (132 mg/dl) was transported essentially by LDL (27%) and HDL (56%). Conversely, the bulk of triglycerides (114 mg/dl) circulated in VLDL (54%). One week of hypercholesterolemic diet increased plasma cholesterol (+80%) and it is reflected in a 3.3-fold increase in VLDL, 2.8-fold in IDL, 1.6-fold in LDL and 1.5-fold in HDL, accompanied by a rise in cholesterol hepatic level by a factor of 4.5. 15 days of treatment with fenofibrate (300 mg/kg/d) produced a decrease in free plasma cholesterol (-21%) without modification in total cholesterol level in chow fed animals. In liver, cholesterol was reduced by 27% and triglycerides were raised by 58%. In animals receiving the hypercholesterolemic diet, fenofibrate increased hepatic and plasmatic triglyceride levels (55 and 54%, respectively), although it slightly reduced plasma cholesterol levels and more markedly the hepatic cholesterol content (-55%). In chow fed animals, cholesterol biosynthesis was decreased by fenofibrate treatment by 40%. The effects of fenofibrate on triglyceride levels are in contrast to experiences in other animal species, including man, and indicate a hypersecretion of chylomicrons and/or a hypersecretion of VLDL, although the explanations are not yet obvious. The results concerning cholesterol metabolism indicate similarities between man and hamster.