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The following HTML text is provided to enhance online readability. Many aspects of typography translate only awkwardly to HTML. Please use the page image as the authoritative form to ensure accuracy. evidence of carcinogenicity at dietary concentrations up to 10,000 ppm of HBCD. The available genotoxicity data suggest that HBCD is not genotoxic. The potential carcinogenicity of HBCD in humans cannot be determined based on inadequate data for an assessment of carcinogenicity via the dermal, inhalation, or oral routes. EXPOSURE ASSESSMENT AND RISK CHARACTERIZATIONNoncancer AssessmentDermal ExposureThe assessment of noncancer risk for the dermal route of exposure is based on the scenario described in Chapter 3. This exposure scenario assumes that an adult spends 1/4th of his or her time sitting on furniture upholstery backcoated with HBCD and also assumes that 1/4th of the upper torso is in contact with the upholstery, and clothing presents no barrier. Exposure to other chemicals present in the backcoating was not included in this assessment. First IterationAs a first estimate of exposure, it was assumed that the skin and clothing of the person sitting on the couch, and the fabric of the couch, would present no barrier to movement of HBCD. In addition, it was assumed that there would be sufficient water present (e.g. from sweat) to allow dissolution of the HBCD in the water, and transfer to the skin and into the body of the sitting individual. The only limiting factor on the transfer rate using these assumptions results from the limited dissolution rate from the fabric—all the HBCD that dissolves is assumed to be absorbed immediately by the sitting individual. Dermal exposure was estimated using Equation 1 in Chapter 3. For this calculation, the subcommittee estimated an upholstery application rate (Sa) for HBCD of 5 mg/cm2. The extraction rate (µw) by water for HBCD was estimated to be 0.025/d based on extraction data for HBCD in polyester fiber (McIntyre et al. 1995). This release rate was calculated as 0.04/d at 28°C from the fiber, with a correction from fiber to film of a factor of 0.63 (2d/2πR for film thickness d, fiber radius R). Using these values, the estimated dermal absorbed dose rate was determined to be 0.98 mg/kg-d. Although lack of sufficient data precludes deriving a dermal RfD, the oral RfD (0.2 mg/kg-d) is used as the best estimate of internal
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