Mutagenicity as a parameter in surface water monitoring programs—opportunity for water quality improvement

Abstract

Effect-based analyses are being recognized as excellent tools to a comprehensive and reliable water quality evaluation to complement physical and chemical parameters. The Salmonella/microsome mutagenicity test was introduced in the São Paulo State water quality-monitoring program in 1999 and waters from 104 sites used to the production of drinking water were analyzed. Samples were tested after organic extraction, using the microsuspension version of the Salmonella/microsome assay with strains TA98 and TA100 with and without S9-mammalian metabolic system. Of the 1720 water samples analyzed in 20 years, 20% were positive; TA98 was the most sensitive strain, detecting alone 99%. Results were presented in hazard categories to facilitate water managers' understanding and general public communication. Hot spots of mutagenicity were identified, and pollution sources investigated. A flow scheme with instructions of how to proceed in case of mutagenic samples was developed and implemented in the monitoring program. Enforcement actions were taken to reduce exposure of humans and aquatic biota to mutagenic compounds. The results presented provide scientific basis for the incorporation of the Salmonella/microsome assay in a regulatory framework, and to guide water-quality managers. The inclusion of a mutagenicity assay using standardized conditions proved to be an opportunity to improve the quality of water, and the strategy presented here could be applied by any environmental agency around the world.

Bioanalytical Tools in Water Quality Assessment

“…The Salmonella preincubation assay is a modified Ames mutagenicity assay (Kargalioglu et al, 2002;Plewa et al, 2004b), which is run in conjunction with the Salmonella typhimurium microplate cytotoxicity assay and was applied to assess DBPs. Most of the studies on mutagenicity testing of water quality simply reported a positive or negative response (Berninger et al, 2019;Albergamo et al, 2020), without determining an effect concentration (EC) or bioanalytical equivalent concentration but there is also guidance on how to interpret such data (Roubicek et al, 2020). Table 10.33 includes only studies that have reported an EC value, with studies reporting the effect concentration inducing a revertant ratio of 1.5 (EC RR1.5 ).…”

Deuterium-depletion has no significant impact on the mutation rate ofEscherichia coli, invalidating the Double D-Bridge Hypothesis

“…It is noteworthy however that in the seminal paper the smallest change of mutant frequencies judged to be significant was a 4.4-fold increase [58]. In a study analyzing the mutagen-content of natural waters using a similar technique, the minimal effective dose required for doubling the mutant frequency (MED2) was declared as a relevant parameter to be calculated for all samples [59]. When reporting the mutagenicity of chemicals, many times the dose-dependent effect is demonstrated.…”

Deuterium-depletion has no significant impact on the mutation rate of Escherichia coli, deuterium abundance therefore has a probabilistic, not deterministic effect on spontaneous mutagenesis

“…It is noteworthy however that in the seminal paper, the smallest change of mutant frequencies judged to be significant was a 4.4-fold increase [59]. In a study analyzing the mutagen-content of natural waters using a similar technique, the minimal effective dose required for doubling the mutant frequency (MED2) was declared as a relevant parameter to be calculated for all samples [60]. When reporting the mutagenicity of chemicals, many times the dose-dependent effect is demonstrated.…”