Currently, chemical substances and pesticides are evaluated and managed by various laws and regulations in Japan. However, there are some problems from the viewpoint of impact on the ecosystems. Tetramethylammonium hydroxide (TMAH), which is mainly used in the manufacturing process of semiconductors and liquid-crystal panels, is not subject to effluent regulation under the Water Pollution Control Law. Reproduction test with Ceriodaphnia dubia indicates a high sensitivity of this species to TMAH. Therefore, TMAH concentration in wastewater discharged should be managed toward the protection of aquatic organisms. Carbendazim is the hydrolysate of benomyl and thiophanate-methyl, which are the active ingredients of pesticides, in the environment. Carbendazim has been detected in environmental water and sediment in Japan, but degradation products are not considered in pesticide registration system in Japan. We conducted sediment-water toxicity test of carbendazim with Chironomus yoshimatsui, and toxicity value was obtained. It is necessary to consider the toxicity value of carbendazim when evaluating the toxicities of benomyl and thiophanate-methyl in sediment in the future. Governments, companies and researchers need to continue to address these issues of chemicals that affect ecosystems.