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Is There Benzene in the Air we Breathe?
When benzene is released into the environment it easily evaporates into the air. Many urban areas have measurable quantities of benzene in the air. One source of benzene is gasoline for automobiles. Regular unleaded gasoline may contain up to 5 percent benzene. Benzene can also be released to the air from tobacco smoke, glues, paints, furniture wax, and detergents. Benzene emissions are a concern because long term exposure to high levels of benzene is known to cause leukemia, a type of cancer, as well as other health problems in humans.
The average amount of benzene in outdoor air can be determined by collecting outdoor air samples and analyzing them. The Missouri Department of Natural Resources (MDNR) has taken samples of outdoor air in Sugar Creek twice and additional sampling is planned to determine if high benzene concentrations are occurring in Sugar Creek outdoor air. Sampling is being done because citizens have expressed concern about odors that they believe may be attributable to the former Amoco Refinery. Results will be evaluated by the Agency for Toxic Substances and Disease Registry (ATSDR) for impact on public health. EPA has collected about 15 outdoor air samples during its basement air sampling program. All benzene levels were below 1 part per billion (ppb) for these samples.
A fact sheet about the health effects of benzene can be found at the ATSDR web site at http://www.atsdr.cdc.gov/tfacts3.html. Information about cancer risks from different concentrations of benzene in air can be found at EPA's Integrated Risk Information System (IRIS) web site at http://www.epa.gov/iris/subst/0276.htm. The following estimates of cancer risk from breathing benzene in air are maximum likelihood estimates for lifetime exposure. These estimates assume the person will breathe this concentration of benzene in air over a 70 year lifetime.
Benzene concentration |
excess lifetime cancer risk |
13.0 to 45.0 g/m3 (micrograms per cubic meter) |
1 in 10,000 |
1.3 to 4.5 g/m3 |
1 in 100,000 |
0.13 to 0.45 g/m3 |
1 in one million |
A person who is exposed for a lifetime to 1 g/m3 (about 0.3 parts per billion) benzene in air has an increased cancer risk of 2.2 to 7.8 in one million.
EPA uses models to estimate the concentrations of various toxic pollutants in outdoor air throughout the United States. This information can be found on the EPA web site at http://www.epa.gov/ttn/atw/nata/mapconc.html. The estimate for benzene in Jackson County is in the range of 1.43 to 4.75 micrograms per cubic meter. EPA strongly cautions that these modeling estimates should not be used to draw conclusions about local concentrations. Information about benzene concentrations in the outdoor air of Sugar Creek is best obtained from actual measurements planned by MDNR.
Note: Benzene measurements of micrograms per cubic meter ( g/m3) can be changed to parts per billion (ppb) by dividing the number by 3.25. Measurements of ppb can be changed to g/m3 by multiplying the number by 3.25.
