Toxicity Assessment of Fly-ash Eluate by Japanese Medaka (Oryzias latipes) and Bivalve Mussel (Mytilidae sp.)

Domestic and non-industrial wastes have been incinerated to control mass volumes and to stabilize the quality of environment. Incinerated residues including fly-ash are being reclaimed in landfill sites. Fly-ash from waste incineration is known to contain numerous metal species and intact environmental pollutants such as dioxins, PCBs and PAHs. To investigate the toxicity of fly-ash, test solutions extracted from fly-ash, collected from six different sources, were prepared and exposed to freshwater fish Japanese medaka (Oryzias latipes) and marine bivalve mussel (Mytilidae sp.) . For medaka, effects of exposure to fly-ash were assessed by monitoring hatching inhibition, acute lethal toxicity, induction of CYP1A and vitellogenin; for mussel, comet assay (as estimation of DNA damage) and induction of GST activity were monitored. All fly-ash eluate solutions exhibited lethal toxicity to medaka and the LC 50 values (96 hrs) were less than 40% concentration of elutes. Hatching inhibition, delayed hatching, spinal deformity of hatched embryo, inductions of CYP1A activity and vitellogenin were observed in exposed medaka. DNA damage and induction of GST activity were observed in exposed mussel. These results supported our previous study on toxicity of leachate from landfill sites with medaka bioassay. Fly-ash participates in contributing to leachate toxicity. Treated leachate still exhibited ecotoxicity that are released into river. In addition to the conventional methods, more appropriate means for leachate treatment and environmental risk management of waste disposal landfill sites are in need for the prevention of ambient environmental pollution.