In response to environmental problems such as environmental pollution and global warming, realizing a safe and secure society is a critical issue in our country. In this paper, polychlorinated biphenyl waste disposal, conservation energy, and controlling chlorofluorocarbon emissions are introduced as part of MEXT's efforts to address environmental issues.
Regarding polychlorinated biphenyl waste disposal, reliable treatment by deadlines stipulated by laws and regulations is being conducted in accordance with the "Basic Plan of Polychlorinated Biphenyl Waste Disposal" (hereinafter referred to as "Basic Plan").
Regarding energy conservation, as the competent minister of the "Act concerning the Rational Use of Energy" (hereinafter referred to as "Energy Conservation Act"), MEXT provides advice and guidance on energy conservation measures to businesses under the jurisdiction of MEXT.
Regarding measures to control chlorofluorocarbon emissions, based on the "Act concerning the Rational Use and Proper Management of Fluorocarbons" (hereinafter referred to as "Freon Discharge Restraint Law"), MEXT provides the technical advice necessary to optimize the management of fluorocarbons.
In this study, we examined the effects of waterborne zinc on accumulation of copper to gill tissues of Oryzias latipes. In zinc exposure tests, concentrations of zinc in exposed group ranged from 17.6-22.3 µg g−1, showing similar levels with the control group (18.5 ± 4.5 µg g−1) and weak accumulation potential of this element. In copper exposure tests, residual levels of copper in gill tissues in the presence (nominal: 100 µg-Zn L−1) and absence of zinc conditions were determined. Concentrations of copper in gill tissues were in the range of 21.9-86.3 and 15.2-156.9 µg g−1 for with and without of zinc,respectively. Calculated maximum binding capacities (Bmax) for copper to gill tissues were 77.0 and 138.4 µg g−1 for with and without of Zn, respectively. The protective effects of zinc would be due to competition for biotic ligands. The results in this study indicate that in actual environments, waterborne zinc would mitigate copper accumulation.