Mutagenic activity water samples

Figure 9. Mutagenic activity in Dutch surface waters A, locations of sampling B, mutagenic activity corresponding to concentrates of 1 L of water, as measured with TA98. (Reproduced with permission from...

Figure 1. Effect of resin type on the mutagenic activity of drinking water concentrates in the Ames test. The sampling, 7000-fold concentration with either XAD-2 or XAD-4/8, DMSO elution (20 mL, neutral fraction), and subsequent mutagenicity testing were as described in Materials and Methods. Similar concentrates of The Hague tap water were used as controls. Each point represents the average of four plates, and 0.50 mL of concentrate corresponds to 3.5 L of water per plate.

Figure 10. Influence of a chlorine treatment on the mutagenic activity detectable with TA98NR and TA100NR strains. Sampling, 7000-fold concentration of water samples before and after a chlorine treatment (1.5 mg/L of Ch) on XAD-4/8, elution with DMSO (neutral fraction)> and subsequent testing of the DMSO concentrate in the Salmonella mutagenicity test were as described in Materials and Methods. Each value represents the average of three plates, and 0.2 mL of concentrate corresponds to 1.4 L of...

The use of the MRR procedure in this study was applied to water samples from a combined ozonation-GAC process in which several ozone doses and ozone contact times were evaluated. The goal was to determine the effects of the combined treatments on the micropollutants and mutagenic activity. In this chapter, data from gas chromatographic (GC) analyses are not reported. Compounds identified by GC-mass spectrometry (GC-MS) and their concentration ranges at the different points of the pilot plant have been published in references 9 and 10. Sampling points allowed for the comparison of the various ozone treatments alone or in combination with GAC and the determination of the effects of postdisinfection. 

Ames Test. Salmonella tryphimurium strains TA98 and TA100 were employed according to the Ames test (15, 16) to determine the mutagenic activity of the various water samples. Each DCM and MeOH extract was tested with and without S9 (microsomal fraction of activated rat liver with Arochlor 1254) activation. For each assay (16 assays per sampling point), the number of revertants per plate was plotted versus increasing volumes of water extracts injected. Slope values from linear regression of the dose-response curves were calculated and then used in the statistical analysis. 

HPLC Fractionation of Extracts of Treated Water. Capillary GC-MS analysis of the XAD-2/ethyl ether extracts of water sampled before and after final chlorination showed no significant difference that could account for the mutagenic activity observed after chlorination. These results indicate that the mutagenic compounds present in the extracts of drinking water are not readily amenable to analysis by GC-MS. However, the possibility cannot be excluded that the mutagenic compounds were present below the detection limit or that they were masked by other compounds. 

Figure 1. Comparison of TA100 mutagenic activities in treated waters sampled before and after chlorination (a) XAD-2/ethyl ether extracts and (b) freeze-dried/methanol extracts.

Table III. Mutagenic activity expressed as revertants per plate (TA98+S9) of model reaction systems (creatinine, glucose, amino acid in diethylene glycol-water 6 1, v/v). Samples in triplicates were directly withdrawn from the mixtures after 1, 2 and 4 h of reflux. 50 pi were used per plate. Comparison of mutagenic activity after corrections for spontaneous revertants between model mixtures containing alanine or glycine.

Table IV. Effect of Maillard reaction products (2-methylpyridine or 2,5-dimethylpyrazine) on the mutagenic activity of different model reaction mixtures (creatinine, D-glucose, amino acid in diethylene glycol-water 6 1, v/v) after 4 h of refluxing, 10-yl samples being directly withdrawn from the reaction mixtures and assayed with TA98 after S9 activation.

Figure 4. Effects of variation of initial water content on mutagenicity of ground beef Samples are fried at 200 °C for 6 min per side and the basic fraction is tested for activity in the Salmonella mutagenesis assay. (The and O are data from two separate experiments.) The original fat-to-protein ratio of approximately 0.8 in the ground beef was maintained in these samples.

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