Benzene

Benzene is found in the ambient air from motor vehicle exhaust,
evaporation from gasoline service stations, wood burning,
industrial solvent use and tobacco smoke. Air around heavy
traffic, gas stations or hazardous waste sites may contain
higher
levels of benzene. Benzene occurs naturally in crude oil and is
a byproduct in gasoline. In addition, aromatics such as benzene
have anti-knock characteristics and are added to gasoline to
increase performance. Benzene remains in the air for a few
hours
to a few days. It is volatile and found primarily in the air
rather than soil or water. Other than workplace exposures or
well contamination, people are generally exposed to benzene
through breathing tobacco smoke or contaminated ambient air. In
Minnesota, benzene is found in both rural and urban air,
although
concentrations tend to be higher in larger towns and cities due
to increased traffic and gas station density.

Acute (short-term) inhalation exposure of humans to benzene may
cause drowsiness, dizziness and headaches, as well as eye, skin,
and respiratory tract irritation, and, at high levels,
unconsciousness. Chronic (long-term) inhalation exposure has
caused various disorders in the blood, including reduced numbers
of red blood cells and aplastic anemia, in occupational
settings.
Reproductive effects have been reported for women exposed by
inhalation to high levels, and adverse effects on the developing
fetus have been observed in animal tests. Increased incidence
of
leukemia (cancer of the tissues that form white blood cells)
have
been observed in humans occupationally exposed to benzene. EPA
has classified benzene as a Group A, human carcinogen.