Benzene is a widely used chemical formed from both natural resources
(volcanoes and forest fires) and human activities. It is a highly flammable
colorless liquid that evaporates quickly. Relatively soluble in water, it can
be mixed with some polar solvents (alcohol, chloroform, and carbon
tetrachloride) without separating into two phases.
Its chemical formula is C6H6 and it is made up of 92.3%carbon and 7.7%
hydrogen. The Benzene molecule is represented by six sets of carbon and
hydrogen atoms connected as a hexagon and held together with alternating single
and double bonds.Its chemical and physical properties are as follow:
Molecular Weight 78.11 g/moleMelting Point 5.5 degrees CelsiusBoiling Point
80.1 degrees CelsiusDensity at 20 degrees Celsius 0.879 g/mlVapor Pressure at
25 degrees Celsius 0.13 atm.Flash Point (closed cup) -11.1 degrees Celsius
Solubility in Water at 25 degrees Celsius 1.8 g/LConversions at 25 degrees
Celsius 1 ppm = 3.25 mg/m31 mg/liter = 313 ppm
ppm = part per million
Is it Dangerous?
In the 1980’s, benzene replaced lead in gasoline, when the latter was proven
to be toxic. Unfortunately, the trade off turned out to be merely one poisonous
substance for another.
Benzene has been confirmed as a human carcinogen (cancer-causing agent) by
the International Agency for Research on Cancer, the Department of Health and
Human Services (DHHS), and the Environmental Protection Agency (EPA).
Is it Regulated?
The EPA requires that spills or accidental releases into the environment of
10 pounds or more of benzene be reported to the EPA. The EPA has set the
maximum permissible level of benzene in drinking water at 0.005 milligrams per
liter (0.005 mg/L).
The Occupational Safety and Health Administration (OSHA) has set an exposure
limit of 1 part of benzene per million parts of air (1ppm) in the workplace
during an 8-hour workday in a 40-hour workweek, with a short term exposure of
limit of 5ppm. Long term exposure has been shown to affect bone marrow and
cause serious and life-threatening health conditions.