Application of Biotests for Toxicity of Leachate and Evaluation Monitoring

Shino Mohri*, Hiroshi Nagashima**+, Yasuaki Miyahara**, Yoshiro Ono***
Osami Kawara***, Manabu Kunimoto**** and Isao Somiya*****
* Research Center for Material Cycles and Waste Management National Institute for Environmental Studies
** The Graduate School of Natural Science and Technology, University of Okayama
**+ Present address: Graduate School of Science and Technology, Kobe University
*** Department of Environmental and Civil Engineering, University of Okayama
**** School of Pharmaceutical Science, Kitasato University
***** Department of Environmental Engineering, Graduate School of Engineering, Kyoto University
+ Correspondence should be addressed to Shino Mohri:
(16-2 onogawa, tsukuba-city, ibaragi, 305-8506 Japan)

Abstract
To develop a more applicable means to screen for toxicity, we have selected a battery of three biotests for a six-month monitoring period of the risk in leachate from a landfill site. To validate this battery, we measured genotoxicty, proliferation activity of MCF-7 and cytotoxicity of leachate, its treated effluent and receiving river waters once a week. A new measure, named Negative Dilution Factor (NDF) become apparent from umu-test. In the experiments genotoxicity was detected in leachates, and reduced through the treatment process. Leachate showed same seasonal changes in proliferation activity of MCF-7 cells in river samples. Since the average proliferation activity of MCF-7 cells in leachate was low, there may be little effect of leachates on the river. Cytotoxicity of leachate and treated effluent were stronger than river water but almost all of these toxicities were less than 50% inhibitiing. Cytotoxicity was observed in concentrated samples from a landfill site, but it derived from osmotic pressure by salinity. As the maximum cytotoxicity of treated effluent was 9 times that of upstream samples, it may be necessary to dilute treated effluent about 10 times for the management of impact on the environment.

Key words: leachate, umu-test, E-SCREEN assay, cytotoxicity test, monitoring