Heavy metal wastewaters (Wastewater A: inorganic waste containing heavy metals as well as ferrous sulfate and alkaline after treatment for removal of mercury, fluoride, phosphate and cyanide, Wastewater B: additional treatment by ferrite formation, activated carbon and alumina added to wastewater A) were analyzed using a yeast DNA microarray to elucidate the toxic mode of action. Differences were observed in both the number of genes induced and Munich Information Center for Protein sequence (MIPS) functional categories between these heavy metal waste samples. The expression of a number of genes changed in response to exposure to heavy metal wastewater A. After treatment of heavy metal wastewater A with ferrite formation, active carbon and alumina, wastewater B decreased the number of induced genes in every category except that concerned with regulation and interaction with the cellular environment, while the number of repressed genes decreased in every category. These results suggest that a DNA microarray can be a powerful tool for bio-monitoring the fate of heavy metals in the environment, and for evaluating the effectiveness of water treatment systems in reducing heavy metals.

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Effects of dietary fenthion (hereafter MPP), an organophosphorus insecticide, on mortality of damselfly larvae, Ischnura senegalensis, and freshwater shrimp, Macrobrachium nipponense, were assessed using an insecticide-tolerant strain of Chironomus yoshimatsui (Chironomid) as a prey organism. Midge larvae had been exposed to MPP of 125, 250, 500 and 1000 μg/L, respectively, for 24-hrs, and resultant, accumulated MPP at 0.9, 2.1, 11.8 and 68 ng/g (wet wt.). In addition, fenthion sulfoxide (FSO) was detected in the midge larvae at higher levels rather than MPP itself. Individual shrimp and damselfly larva (each, ten replicates) were daily fed on MPP accumulated midge larvae (3 or 4 individuals/d) in a flowthrough aquarium. All damselfly larvae died within 3 days by ingesting the midge larvae accumulated 2.1 (2.8) or 11.8 (17.7) ng/g of MPP (FSO in parentheses). While, mortality of the shrimp fed on the midge larvae accumulated 0.9 or 2.1 ng/g MPP increased slowly to 40 and 80%, respectively, until 24 days after start of the experiment. Both predators continued to eat the MPP-accumulated midge larvae without showing hesitation, suggesting that they lack ability to keep away from toxic prey. We estimated the exposure levels of MPP and FSO in the live midge larvae that brought 50% mortality of predators used for the tests.

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he immunotoxic effects of tributyltin (TBT) exposure on the respiratory burst activities of neutrophils in head kidney (HK) and peripheral blood (PBL), and lysozyme activities of plasma were examined in rainbow trout (Oncorhynchus mykiss). After fish were exposed to TBT at the concentration of 5, 10 and 20μg/L for 5 days, and 5μg/L for 14 and 28 days, leukocytes obtained from HK and PBL were evaluated for the active oxygen production by flow cytometry (FCM). The contents (%) of neutrophils population in total leukocytes collected from HK of fish exposed to 20μg/L of TBT for 5 days was clearly increased compared with the control group. However, respiratory burst activity of neutrophils in the exposure group decreased compared with the control group. The increase of neutrophils from fish exposed to 5μg/L of TBT for relatively long term exposure (14 and 28 days) was observed only in PBL. These results indicate that high level exposure of TBT stimulated immune function of rainbow trout temporally, and neutrophils were actively produced in HK, however neutrophils themselves showed weak productivity of active oxygen. It was observed that lysozyme activities decreased in the group exposed to 10μg/L for 5 days, while TBT concentration in blood increased in accordance with the TBT concentration in water ranging from 0 to 10μg/L. We supposed that immunotoxic effects of TBT were apparent both as immunostimulative and immunosupressive, and these immune responses might be dependent on the TBT concentration of exposure.

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The impact of chemical pollution has focused almost exclusively on the high production or notorious toxic chemicals. The drugs have been uninteresting products for researchers despite of their high physiologic activity. The EC₅₀s of 27 antibiotics were determined as the screening test in order to assess the environmental risk. Two (Penicillin G benzathine and Gentamicin sulfate) of 27 antibiotics showed high toxicity (EC₅₀ is less than 1mg/L) against Daphnia magna. The risk assessment with most toxic antibiotic (Penicillin G benzathine) did not show the concerned level.

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