How much harm can be done by the chemical substances in our environment? This question is important when considering the connection between human health and the environment. For this reason, we planned the development of zebrafish (Brachydanio rerio, a species of tropical fish) into which we would introduce a gene to detect the mutagenicity (the tendency of a substance to cause genetic mutations) of chemicals in water. We have already made zebrafish into which we put a monitor gene for detecting mutagens, and we are developing a mutagenicity test method that uses these genetically modified fish. We have confirmed that it is possible to use the embryos of these fish to detect the mutagenicity of benzopyrene and other chemical substances in ambient water.

　We also have plans to detect mutagenic chemical substances in ambient air by using rats and mice into which similar monitor genes have been introduced. We have already detected the mutagenicity of diesel exhaust using genetically modified rats.