To evaluate the toxicity existing in effluent water, three different bioassays, in vitro cytotoxicity tests using three human cell lines, bioluminescene inhibition test using luminescent bacteria and daphnia acute immobilization test, were applied to effluent water samples collected from solid-waste incineration plants. Results obtained from bioassays were compared with the results from chemical and physical analysis.
Toxicity observed with bioassays were not necessarily correlated with individual indices from chemical analysis, such as AOX (adsorbable organic halides), dioxins, heavy metal contents and pH. However, the toxicity to human cell lines and daphnia were well correlated with the osmolarity of the samples. Moreover the dose-response curves coincided well with those of standard osmolarity solutions made of sodium chloride or glucose, suggesting that the osmolarity plays a significant role in the toxic effects of these effluent water samples.
Therefore, for the application of bioassays to effluent water samples, especially in case of in vitro cytotoxicity tests and daphnia test, consideration of the osmolarity of the samples is essential for accurate assessment of their toxicity.