thereby decreasing the potential for hematotoxicity and carcinogenicity. Binary interaction studies in animals similarly indicate that toluene can inhibit the hematological effects of benzene, although data are insufficient to conclude that the
protective interaction would occur at low doses (see Section 2.2.3). Considering the causal relationship
between the noncancer hematological effects of benzene and subsequent manifestation of leukemia, as
well as the lack of a cancer risk value for ethylbenzene, it is recommended that an overall assessment of
the hematotoxic and carcinogenic hazards of BTEX be conservatively based on benzene cancer risk as
discussed in Section 2.3. Benzene, therefore, should be evaluated as a single component using ATSDR
(1992) public health assessment guidance, which indicates that exposure will be a concern if the estimated
risk of cancer equals or exceeds 1x10-6. Increased lifetime cancer risks for inhalation exposure are
estimated by multiplying the unit risk for benzene by the estimated exposure (air concentration).