EFFECTS OF LIGHT-INTENSITY ON THE PHOTOTOXICITY OF FLUORANTHENE TO A BENTHIC MACROINVERTEBRATE

Conceptual models suggest that the toxicity of photoactivated polycycl ic aromatic hydrocarbons (PAHs) should be a direct function both of ch emical (PAH) dose and intensity of the ultraviolet (UV) light to which the organism is exposed. However, there have been only limited studie s with aquatic organisms to quantify the relationship between PAH dose and UV intensity in producing phototoxicity. In this study, oligochae tes (Lumbriculus variegatus) were exposed, via the water, to multiple concentrations of fluoranthene, a PAH known to be phototoxic, and then placed under UV light at three different intensities. The resultant p hototoxicity clearly was a function both of PAH dose and light intensi ty. Time-dependent mortality of the oligochaetes could be accurately p redicted through evaluation of the product of fluoranthene dose (in th e tissue of the animal) and light intensity to which the organisms wer e exposed. These results indicate that criteria for phototoxic chemica ls should incorporate consideration not only of xenobiotic exposure bu t also of light intensity in specific aquatic environments.