GENOTOXICITY OF DISINFECTION BY-PRODUCTS USING COMET ASSAY

Abstract

Bromoform and Chloroform are trihalomethanes and are among the most frequently detected drinking water disinfection by-products. They have been associated with various adverse effects on human haematological parameters, which are an important indicators of well-being. The prime objective of current study was to conduct a dose-response assessment to investigate the genotoxic and haematological effects of trihalomethanes on humans. Blood samples of healthy subjects were exposed to different concentrations (10, 30 and 50 μg/mL) of chloroform and bromoform in vitro to analyse how these compounds affected the haematological count with increasing dose concentrations. Headspace gas chromatography analysis was also conducted on samples to assess the difference between measured and spiked values of doses. Comet assay results showed that mean tail lengths values for bromoform (13.6, 23.0, 46.6 μm) were higher than chloroform (13.4, 22.4, 36.8 μm) at the three observed doses, depicting that bromoform has a higher genotoxic potential. Other indexes included were %DNA in Tail (%) and Olive Tail Moment (OTM) which showed the same trend. The haematology results indicated that the target compounds affected some haematological parameters in a dose dependant way. Haemoglobin (HGB) and mean corpuscular haemoglobin concentration (MCHC) levels lowered as they were significantly affected (P<0.05) by bromoform at all administered doses whereas the platelet (PLT) and red blood cell (RBC)count lowered significantly (P<0.05) only at at doses 30 μg/mL and 50 μg/mL. Conversely the damage caused by chloroform was minor (P>0.05). Both the compounds had no significant effect (P>0.05) on hematocrit (HCT) and white blood cell levels (WBC) as compared to the control.