Toxicity screening after degradation of organophosphorus pesticides with chlorine dioxide

Effectiveness, mineralization and toxicity of four organophosphorus pesticides (OPPs) azamethiphos (AZA), dimethoate (DM), fenitrothion (FEN) and malathion (MAL) in water with chlorine dioxide (ClO2) as degradation agent were investigated. Analyses included toxicity tests of parent pesticides and their degradation products (DPs), using Daphnia magna test organisms, and total organic carbon (TOC) analysis. Toxicity tests showed that all four pesticide DPs were less toxic than parent pesticides, but DM had higher toxic DPs compared to parent AZA, FEN and MAL. All DPs were classified as category III (on a scale from I to V) of toxicity as acutely toxic. TOC analysis showed that AZA has lowest (only 18%) and MAL has highest mineralization (56%). Considering the obtained results, it could be concluded that ClO2 efficiently degrades AZA, DM, FEN and MAL and represents good solution for a safer environment