Endosulfan sulfate is one of main metabolites of endosulfan degradation in soil and sediments. It should be noted that some microorganisms can transform endosulfan without producing endosulfan sulfate (Kataoka and Takagi 2013). The concentrations of endosulfan sulfate detected in surface sediments during dry season of rice cultivation area near the tributaries of the Mae Klong River in central Thailand ranged from 0.15 to 0.58 mg kg dry weight (Poolpak et al. 2008). Endosulfan sulfate concentrations have been reported to range from 0.13 to 10.5 mg kg dry sediment near the Wu-Shi River estuary in Taiwan (Doong et al. 2002). This metabolite is as toxic as but is less biodegradable, more persistent in the environment, and has greater bioaccumulation potential than its parent com pound (Bhalerao and Puranik 2007; Kataoka and Takagi 2013; Weber et al. 2010) .