MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(KWO-1117-228313) Relationship between pre-existing body residue of polychlorinated biphenyls and toxicity to subsequent exposure to PCBs in Hyalella azteca.

Kwon, T-D¹, Fisher, S¹, ¹ Department of Entomology, The Ohio State University, Columbus, Ohio, USA

ABSTRACT- The relationship between pre-existing body residues and toxicity was determined. Hylella azteca was observed to examine the mortality delay in the presence of relatively lower pre-existing PCB body residues. Two parallel exposures were set up for comparison of an effect in the mortality. These included (1) a 10-d exposure to PCB extracts (from smallmouth bass) prior to performance a 10-d toxicity test with PCB 153 or PCBs mixture (PCB 47+126+153). (2) The second was exposed to uncontaminated algae following exposure to PCB 153. In comparison to significant mortality in the PCB 153 exposure, both in the presence or absence pre-exposure to PCBs extract, no mortality was observed in the PCB mixture in spite of statistically similar body residues. The mortality in the PCB 153 treatment after twice pre-exposure, PCBs extract and PCB mixture, was ranged from 46.7 to 60.0 %, despite the fact that exposure concentration was already showed near 100 % mortality in the PCB 153 exposure in the presence or absence pre-existing body residues. The relationship between CBR and time-to-death showed a positive correlation, suggesting an increase in adaptability against chemical stress.

Key words: Mortality delay, LR₅₀, Hyalella azteca, Polychlorinated biphenyls (PCBs)