Changes of the toxic potential of drinking water containing aminopyrine before and after chlorine disinfection as determined by the algal toxicity assay and the SOS/umu assay

• Acute toxicity and genotoxicity were observed after AMP chlorination.
• Acute toxicity declined at relatively low chlorine doses in algal toxicity test.
• Enhancive genotoxicity was achieved with chlorine doses increase in SOS/umu test.

This paper investigated the potential eco-toxicity changes of the drinking water containing aminopyrine (AMP) before and after chlorination. For the determination of the acute toxicity and genotoxicity, algal toxicity assay and SOS/umu assay were adopted respectively. In these toxicity assays, the AMP exposure group was compared with the control group or the chlorination group to illustrate the changes. Results showed that the algal growth inhibition percentage increased with the increase of AMP concentration. After AMP chlorination, the inhibition percentage decreased at relatively low chlorine ratios (i.e., the AMP to chlorine molar ratio of 4:1 and 1:1) but increased at high chlorine ratios (i.e., the AMP to chlorine molar ratio of 1:2 and 1:5). The superoxide dismutase (SOD) activity was stimulated at AMP to chlorine molar ratios of 4:1 while inhibited at 1:5. The change of malondialdehyde (MDA) content was just opposite to the SOD activity. In SOS/umu assay, when the molar ratios of AMP and chlorine were 1:1, 1:2 and 1:5, the values of induction ratio (IR) were over 1.5 and showed a positive genotoxicity signal in the absence/presence of S9 homogenate. Further, the Toxic Equivalent Quantity (TEQ) value, which was used to express the genotoxic potentials of those positive samples, gradually increased with the increase of chlorine ratio. In a word, the potential genotoxicity of chlorinated drinking water containing AMP should be of a concern.