Pesticide waste leachate toxicity evaluation and hazard quotient derivation by Allium assay

This study was envisaged to explore the impact of pesticide solid waste leachate to Allium cepa (common onion) bulbs. Bulbs exposed to the leachate showed hampered root growth and morphological deformities. At 15% and higher concentrations of leachate after 5 days, gall like swellings were noticed around the mitotic zone (zone of root growth). From the dose response curve, the EC50 values for the 5 th, 10th, 15th and 20th day were calculated and the highest EC50 value, 24.9%, was for the 5th day while the lowest EC50 value, 20%, was for the 20 th day. The EC50 decreases from 5th to the 20th day successively. The 5th day EC50 was used to determine the hazard quotient (HQ) of the pesticide waste leachate from the dumping site. A value of 4.49 as HQ suggests that that there is considerable risk, as any value of HQ above one (>1) is environmentally unacceptable. The response in root growth pattern, residue analysis and the HQ indicates that the leachate is toxic to rot growth of onion and steps for proper management of hazardous waste and leachate are urgently required.