Phototoxicity of quinalphos under sunlight in vitro and in vivo.

The phototoxicity of quinalphos (QP) under sunlight was studied by investigating skin sensitization, mouse tail and ear swelling tests and generation of activated oxygen species (AOS). Quinalphos, at an oral dose of 5 mg/kg to the mouse, did not produce any change in water content of the tail, but produced ear swelling under sunlight (60 min). The pesticide did not produce any skin sensitization reaction when applied on depilated skin of guinea pigs (100-500 microg/cm2) and irradiated under sunlight (60 min). Furthermore, the compound produced a significant amount of AOS such as singlet oxygen (1(O2)) and superoxide anion radical (O2- under sunlight. The production of AOS was both concentration (1-20 microg/ml) and irradiation time (0-40 min)-dependent. The generation of AOS was also confirmed by using quenchers of singlet oxygen (sodium azide and DABCO) and superoxide anion radical (SOD).