Mutagenicity biotests on the other hand are rapid, relatively cheap and predictive of integral mutagenic/carcinogenic activity, and can evaluate the combined action of potentially hazardous compounds present in drinking water as complex mixtures and not only a specific compound like by biosensors. They are able to take into consideration the bioavailability of (geno)toxic compounds, their synergism, aditivism or even antagonism. They provide the answer of an organism/cell, the actual effects, of the whole mixture of (geno)toxic compounds potentially present in drinking water samples or in other environmental samples. Toxic and genotoxic action in fact is the consequence of addition, synergism, antagonism and bioactivation what can be directly shown only by biote