The role of reactive oxygen species in the degradation of lindane and DDT.
We have studied the photodegradation reactions of lindane and DDT under sunlight (72 hr) or a solar simulator (2 hr) either directly or in presence of selected photodynamic sensitizers. Direct photolysis did not cause noticeable degradation of the pesticides (below 1% in both the cases). However, addition of benzophenone or rose bengal to the irradiation solution of lindane resulted in 88% and 47% degradation, respectively, under sunlight. Similar experiments carried out with DDT resulted in 89%, 50% and 32% degradation with benzophenone, rose bengal and methylene blue, respectively. All the photosensitizers used for the study have been shown to induce photooxidation reactions by generation of reactive oxygen species. These studies suggest that by employing certain naturally occurring photosensitizers with reactive oxygen generation potential under sunlight, an effective method for safe removal of pesticides and other environmentally persistent agents from the surface of earth can be developed.