Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p9
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 9/13)
Character Range: 2387889–2391016

of exposure (calculated as per US EPA 2006). Other uncertainties have also been noted in the above discussion, particularly in relation to the selection of the oral TRV (where the value from MfE (2011) may also be considered, although it is a draft) and dermal exposures.

With respect to the derivation of HIL A, the following can be noted:
    * HIL A = 20 mg/kg on the basis of the recommended oral TRV from MfE (2011) (also adopted for dermal exposures) and no additional consideration of early-lifetime exposures.
    * HIL A = 8 mg/kg on the basis of the oral TRV from WHO (2011) (also adopted for dermal exposures) and no additional consideration of early-lifetime exposures.
    * HIL A = 6 mg/kg on the basis of the recommended oral TRV from MfE (2011) (also adopted for dermal exposures) and consideration of early-lifetime exposures[1];
    * HIL A = 3 mg/kg on the basis of the oral TRV from WHO (2011) and consideration of early-lifetime exposures1.
    * HIL A = 0.3 mg/kg on the basis of the recommended oral TRV from MfE (2011), but consideration of the dermal slope factor presented by Knafla et al. (2011) and no consideration of early lifetime exposures. Note that the HIL is lower (0.1 mg/kg) if early lifetime exposures are assessed for oral intakes.
With consideration of the uncertainties (particularly in relation to the assessment of dermal exposures) identified and the effect of these on the derived HIL A value (noted above), it is recommended that the lower value derived on the basis of the WHO (2011) oral TRV (also adopted for dermal exposures) with consideration of early-lifetime exposures (for HILs A, B and C only), that results in the calculation of HIL A = 3 mg/kg, be adopted.

It is noted that while the approach adopted for the derivation of the HILs has not directly incorporated the dermal approach outlined by Knafla et al. (2011), individual jurisdictions may require consideration of these issues in a site-specific assessment, particularly where people may come into direct contact with coal tar.

On this basis, the following HILs are recommended for BaP and carcinogenic PAHs (assessed as BaP TEF) (refer to Appendix B for equations used to calculate the HILs and Appendix C for calculations):
HIL Scenario            HIL* (mg/kg)                     Percentage Contribution from Exposure Pathways
Ingestion of Soil/Dust  Ingestion of Home-grown Produce  Dermal Absorption of Soil/Dust                  Inhalation (dust)
Residential A           3                                46                                              --                 54  <1
Residential B           4                                17                                              --                 83  <1
Recreational C          3                                29                                              --                 71  <1
Commercial D            40                               18                                              --                 82  <1

-- Pathway not included in derivation of HIL
* Noted that as the dermal absorption pathway dominates the derivation of HILs A, B and