Changes Of The Toxic Potential Of Drinking Water Containing Pyrazolone Drugs Before And After Chlorine Disinfection

In recent years, pyrazolone drugs have been detected in drinking water frequently. It was reported that different disinfection by-products (DBPs) were formed during chlorination. These DBPs are more likely to have a greater toxicity than the original parent compounds, and threaten the human health. Therefore, it is important to study the changes of the toxic potential of drinking water containing pyrazolone drugs before and after chlorine disinfection.This study chose three typical pyrazolone drugs-antipyrine (ANT), aminopyrine (AMP) and propyphenazone (PRP) to investigate the acute toxicity and genotoxicity during chlorination, respectively. The acute toxicity test was characterised by the growth inhibition percentages and enzyme activities of the Chlorella vulgaris(C. vulgaris), and the inhibition rate of luminous bacteria T3. The SOS/umu test was used in the genotoxicity test, and the direct/indirect genotoxicity of the testsamples were determined by the induction ratio (IR) and toxic equivalent quantity (TEQ).The results of algal toxicity test, including the growth inhibition percentages and enzyme activities of the C. vulgaris, showed that the growth inhibition percentage of the C. vulgaris increased with the concentration of pharmaceuticals without chlorination, and the inhibition percentage of AMP was always lower than 50%. After chlorination, it was decreased at relatively low chlorine ratios (ie, the pharmaceutical to chlorine molar ratio of 4:1 and 1:1) but increased at high chlorine ratios (ie, the pharmaceutical to chlorine molar ratio of 1:2 and 1:5) compared to the case before chlorination. The avtivities of superoxide dismutase (SOD) and catalase (CAT) were stimulated at pharmaceutical to chlorine molar ratios of 4:1 while inhibited at 1:5. The change of malondialdehyde (MDA) content was just opposite to the SOD or CAT activity. The results of the luminescent bacteria test showed that there was no effect on the luminance of luminous bacteria T3 before and after those pyrazolone drugs chlorination. The results of SOS/umu test showed that ANT and PRP were genotoxic with and without chlorination, AMP with the genotoxicity when AMP to chlorine ratio was equal to or greater than 1. The genotoxicity of these three pharmaceuticals increased with the increase of chlorine dose. In the action of exogenous S9 metabolic enzyme system, there some substances with higher DNA damage effect were formed before and after pyrazolone drugs chlorination. The acute toxicity of these three drugs is in the order of AMP< ANT<PRP, the genotoxicity of these three drugs is in the order of AMP<PRP<ANT.