(VCCEP) Tier 1 Pilot Submission for BENZENE - Tera

Figure 7.4 Predominant Pathways of Benzene Exposure for Nursing Infants (with
occupationally exposed mothers) from Ambient Sources
Benzene VCCEP Submission
March 2006
Ingestion
22%
7.2.2 Source-Specific Exposures
Dermal
0%
127
Inhalation
78%
Inhalation
Ingestion
Dermal
In addition to the ambient sources of benzene exposure, certain subpopulations of children and
prospective parents may be exposed to benzene in specific microenvironments related to
gasoline exposures during in-vehicle transportation, refueling and use of small engine
equipment, or from tobacco smoke, either through ETS or mainstream smoke. Exposures to
each of these specific sources have been quantified and are discussed below.
7.2.2.1 Gasoline Sources of Exposure
Benzene is among various aromatic constituents in gasoline. As noted in Section 5, benzene
emissions from motor vehicles are on the decline as a result of the 1990 Clean Air Act
Amendments, which called for lower tailpipe emissions, more stringent emissions testing,
expanded inspection and maintenance programs, new vehicle technologies, and clean fuels
programs. Unlike other aromatics in gasoline, benzene has its own reduction requirements. As
of 2002, the average benzene concentration in gasoline (in both conventional gasoline and
oxygenated gasoline) in the U.S. was approximately 1.1% by volume (U.S. EPA 2002a). The
current RFG regulations limit the content of benzene in gasoline to an average of 0.95% by
volume, where RFG is used. However, fuel benzene levels are higher in some non-RFG ozone
attainment areas (e.g. Alaska).
While benzene in gasoline contributes to the overall concentration of benzene in the ambient
air, exposures to gasoline may also occur while riding in a vehicle, during refueling of a vehicle
and use of small engine equipment such as lawn mowers, chain saws, leaf blowers, edge
trimmers, snow blowers, ATVs, and snowmobiles. As such, benzene exposures from these
localized benzene sources have been evaluated.