Workers breathing large amounts of MCB can experience headaches, muscle spasms, and adverse effects on the bone marrow. Other human health effects associated with repeat exposure to small amounts of chlorobenzene over long periods of time are not known. Laboratory studies show that repeat exposure to chlorobenzene in air affects the nervous system of animals. Repeat exposure to large amounts of MCB can also adversely affect the liver, kidneys, and the blood of animals. Results show that exposure to moderate amounts of chlorobenzene in air causes testicular damage in animals.
Chlorobenzene is moderately toxic to aquatic organisms.
Chlorobenzene is not likely to cause environmental harm at levels normally found in the U.S. environment.