One hundred and one pesticides listed as “Complementary Items for Setting the Targets for Water Quality Management in Japan” were divided into 16 groups on the basis of their structures. The degradation of 96 pesticides and 5 oxidation by-products in chlorination was studied to determine the potential of the purification process. Pesticides containing sulfur (S) were easily degraded; for 38 pesticides out of 46 examined pesticides, only 50 % or less of their original concentration remained after 4 hours. On the other hand, pesticides without S were hardly degraded; for 45 pesticides out of 50 examined pesticides, more than 50 % of their original concentration remained even after 24 hours. Thus, the potential for degradation of the pesticides by chlorination can be approximated by the presence or absence of S in their chemical formulae. Oxons (P=O), which are oxidation by-products of organophosphate pesticides containing P=S, were hardly degraded. Therefore, oxons may remain in chlorinated water for a long time.

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A Trichloroethylene(TCE)-degrading bacterium, Methylocystis sp. strain M, isolated from soil has a high TCE degradable activity. When we apply strain M for bioaugmentation, we have to know the behavior of this strain in the contaminant area. We investigated the movement of strain M in glass beads, sandy soil, andosol, and Kanuma soil using a soil-aquifer column. Strain M moved a little slower than NaCl through glass beads, sandy soil, and andosol. This indicated that the movement of strain M was not influenced by adsorption to such soils. In the case of Kanuma soil, strain M moved faster than NaCi. It seemed that the phenomenon was caused by the characteristic structure of Kanuma soil which results in a short-cut route for strain M. The breakthrough curves derivde from the column experiments well fitted the one-dimensional transportation model, which reflected the advection, dispersion, and sorption. We can predict the movement of bacteria in groundwater using the transportation models.

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Several in vitro assays have been developed to assess the activity of estrogenic substances. Recently, a yeast two-hybrid screen or a MCF-7 (human breast cancer cell) screen has been adopted mainly for screening chemicals and environmental estrogenic activity. However a yeast two-hybrid screen does not assay using an animal cell. MCF-7 screen is a complicated assay and the cell used proliferates depending on estrogen, thus obstructing a precise assay for estrogenic activity. In addition both screens need long incubation period (4-6 days) for a highly sensitive assay. The CHOOSER is a Chinese hamster ovary (CHO) cell transformed with the gene encoding the human estrogen receptor (ER α) and an estrogen responsive promoter linked to a reporter gene which was developed by Suzuki et. al. at Osaka prefectural institute of public health. When the reporter gene is activated by estrogenic substances, is expressed, producing alkaline phosphatase which is secreted into the medium. The CHOOSER can assay high sensitively (under 10^-11M as 17 β-estradiol) at any time in a short incubation period (2 days). The number of the CHOOSER can be counted precisely because a CHO is dissociated the aggregates easily with trypsin and form a single cell suspension. And the CHOOSER can proliferate in the medium without estrogen, therefore it is possible to assay for estrogenic activity more proliferate in the medium without estrogen, therefore it is possible to assay for estrogenic activity more precisely. The CHOOSER assay will be a useful prescreening method for estrogenic activity before in vivo assay.

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