These symptoms disappear after exposure stops. From overwhelming human evidence and supporting animal studies, the U.S. Department of Health and Human Services has determined that benzene is carcinogenic. Long-term exposures to benzene may affect normal blood production, possibly resulting in severe anemia and internal bleeding. In addition, human and animal studies indicate that benzene is harmful to the immune system, increasing the chance for infections and perhaps lowering the body's defense against tumors. Exposure to benzene has also been linked with genetic changes in humans and animals.
Animal studies indicate that benzene has adverse effects on unborn animals.
These effects include low birth weight, delayed bone formation, and bone marrow damage. Although benzene has been reported to have harmful effects on animal reproduction, the evidence for human reproductive effects, such as spontaneous abortion or miscarriage, is too limited to form a clear link with benzene. Benzene can be measured in the blood and the breath. The body changes benzene to a chemical called phenol, which can be measured in the urine. The graphs on the following pages show the relationship between exposure to benzene and known health effects.