THE SCREENING OF TOXICITY AND PHOTOCHEMICAL TOXICITY OF DYES BY MEANS OF THE AMPHITOX TEST

CRISTINA PEREZ-COLL, JUAN C. STOCKERT AND JORGE HERKOVITS

Santiago, Chile

Congreso; VII Congreso Setac L. A.; 2005

Setac L. A.

The photodynamic action is exerted by photogenerated reactive oxygen species (ROS) produced after cellular accumulation of a photosensitizer and irradiation with visible light. AMPHITOX test was employed successfully for standardized hazard assessment studies including phototoxic effects as well as the possibility to prevent/reduce adverse effects of different environmental agents. The main purpose of this study was to evaluate the toxicity and photochemical toxicity of 6 dyes and to establish the relationship between their adverse effects and possible photodynamic activity. NOEC-48 h values were evaluated by means of the AMPHITOX test conducted with Bufo arenarum embryos at the end of their development (stage 25) for the following dyes: acridine orange (AO), phloxin (Ph), phloxin B (PhB), rose bengal B (RB), toluidine blue O (TB), and pyronine Y (PY), dissolved in AMPHITOX solution (AS). In previous studies, it was determined that irradiation with white light at a dose of 43.2 J/cm2 (72 mW/cm2 for 10 min) is appropriate to explore the photodamage exerted by chemicals. Embryos were first treated for 48 h with a range of dye concentrations to know the NOEC values. For photodynamic experiments, embryos were subjected 48 h to dyes at NOEC and then they were thoroughly washed and irradiated. The NOEC values (in mg/L) for chemical toxicity and NOEC plus light values for photochemical toxicity were: AO 1 and 0.5; PhB 1 and 0.7; RB 5 and 1; TB 10 and 5; Ph 10 and 10; PY 20 and 20, respectively. The survival of control embryos (maintained in AS and irradiated for 10 min) was not affected. By comparing the chemical/photochemical toxicity ratios of these substances it results that the order for photochemical damage could be expressed as RB > TB > AO > PhB, the remaining dyes showing no phototoxicity. These results point out the possibility to evaluate the phototoxic effect of chemicals by means of a simple test employing amphibian embryos.