Daily Archives: November 20, 2014

“Genome Profiling-based Mutation Assay” Method Proposed for Drinking Water

An interesting approach. But it is premature to conclude that this technique is epidemiologically important. Additional work is needed to validate non-accepted methods and this technique is no different. Further, measuring the generic “mutagenicity” of water is not new and the findings were to be expected. A more sensitive assay may or may not be relevant or useful. To be useful the method results and interpretation must be relevant to human exposure and health risk to specific contaminants. In this case attribution is made to THMs but this may have been premature as there are other differences in water quality between tap water and bottled water. Such a technique may be useful for identifying the more mutagenic contaminants. (As was done in the past for MX.)

Kumari P, Kamiseki M, Biyani M, Suzuki M, Nemoto N, Aita T, Nishigaki K. Detection of ultra-low levels of DNA changes by drinking water: epidemiologically important finding. Journal of biochemistry. 2014 Nov 17. pii: mvu072.

The safety of drinking water is essential to our health. In this context, the mutagenicity of water needs to be checked strictly. However, from the methodological limit, the lower concentration (less than ppm) of mutagenicity could not be detected, though there have been of interest in the effect of less concentration mutagens. Here we describe a highly sensitive mutation assay that detects mutagens at the ppb level, termed GPMA (Genome Profiling-based Mutation Assay). This consists of two steps; i) E. coli culture in the medium with/without mutagens and ii) Genome profiling (GP) method (an integrated method of random PCR, temperature gradient gel electrophoresis (TGGE), and computer-aided normalization). Owing to high sensitivity of this method, very low concentration of mutagens in tap water could be directly detected without introducing burdensome concentration processes, enabling rapid measurement of low concentration samples. Less expectedly, all of the tap waters tested (22 samples) were shown to be significantly mutagenic while mineral waters were not. Resultantly, this paper informs two facts that the GPMA method is competent to measure the mutagenicity of waters directly and the experimental results supported the former reports that the city tap waters contain very low level of mutagenicity reagent trihalomethanes.

Click here for paper (fee).