Benzene is a widely used chemical formed from both natural processes and human activities. Benzene inhalation can cause drowsiness, dizziness, and loss of consciousness; long-term effects include anemia and leukemia.
pdf: Health Effects of Benzene Exposure Presentation from the University of Maryland School of Nursing
CDC: Facts about Benzene
Benzene is also found at oil and gas drilling sites. A study published by researchers at the National Institute for Occupational Health and Safety found high levels of benzene in oil and gas workers.