ABSTRACT
The photodegradation caused by ultraviolet (UV) light may be strongly affected by the naturally occurring photosensitizers. This chapter examines the photolytic fate of some typical pesticides, including the bisthiolcarbamate insecticide cartap hydrochloride, the organophosphorous insecticide pyridafenthion, the non-ester pyrethroidal insecticide etofenprox, and the anilide herbicide naproanilide. It also includes the benzanilide fungicide flutolanil, and the effects of some natural and synthetic photosensitizers on pesticide photolysis, using UV lamps and a photochemical reactor in the laboratory. The chapter shows that UV light caused a variety of photoreactions on the pesticides, and some photosensitizers did accelerate the photolysis, but with different modes of action. The initial process of photosensitization caused by dye sensitizers has generally been classified into two patterns on the basis of their mode of interrelations among the excited dye molecule, the substrate, oxygen, and the ground state dye. One of the two is the process caused by the energy transference mechanism and the other by the electron transference mechanism.
