There are various dyestuffs species to produce reactive oxygen such as singlet oxygen O2 and super oxide radicals. Irradiation with sun light in vitro, the dyestuff like benzanthrone, metanil yellow and p-aminodiphenylamine were found to produce reactive oxygen species such as singlet oxygen (1O2) and/or superoxide radicals (O2-). However benzanthrone produces detectable amount of 1O2 Although metanil yellow and p-aminodiphenylamine (p-ADPA) did not produce detectable amounts of 1O2 under similar conditions. The above dyestuffs are routinely used in textiles, cosmetics, detergents, leather industries as well as food additives. In view of the fact that workers exposed to some of these chemicals during manufacture, pulverization and storage develop edema and even skin cancers in the exposed areas of skin. We believe that activated oxygen species may play a major role in the development of these symptoms.