Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p10
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 10/13)
Character Range: 2390614–2393666

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 C and the exposure assumptions differ little between these scenarios, the HIL remains essentially unchanged. Note derived HILs to 2 significant figures presented in brackets.
Elevated levels of BaP in relatively immobile sources, such as bitumen fragments, do not represent a significant health risk.

1.6              Calculated HILs for Total PAHs
The derived HILs above relate to BaP and carcinogenic PAHs calculated on the basis of a BaP TEF (refer to Section 2.2 of Schedule B(7)). However, there are several hundred PAHs, including derivatives of PAHs of which typically only 16 individual PAHs are analysed in site contamination investigations. These individual PAHs have been identified as the most significant based on: the amount of information available on each individual PAH; the toxicity (suspected to be more harmful than other PAHs), there is a greater chance of being exposed to these PAHs; and of all the PAHs analysed, the 16 selected are the most commonly reported at contaminated sites.

Hence to assist in the assessment of contaminated sites it is relevant to also consider total PAHs. Of the PAHs reported these will comprise BaP and carcinogenic PAHs and other non-carcinogenic PAHs where the following can be noted with respect to the derivation of HILs:
    * BaP and carcinogenic PAHs assessed as BaP TEF should be assessed on the basis of the above HILs.
    * Naphthalene is the most significant volatile PAH and therefore the assessment of this compound should address all significant pathways of concern, including vapour inhalation (not addressed in the HIL for total PAHs). The presence of this compound in soil should be assessed on the basis of relevant guidelines such as the Health Screening Levels (HSLs) (Friebel & Nadebaum 2011).
    * The remaining PAHs are considered non-carcinogenic and include acenaphthene, acenaphthylene, anthracene, fluoranthene, fluorene, phenanthrene and pyrene. Rather than review the toxicity of each individual non-carcinogenic PAH, the published potencies to BaP (or TEFs) available for these PAHs (WHO 1998 and CCME 2008) suggest that individual non-carcinogenic PAHs are at least 100 to 1000 times less toxic/potent than BaP. On this basis a factor of 100 has been applied to the calculated BaP HILs to establish HILs for total PAHs. Review of soil guidelines developed by US EPA (Regional Screening Levels, 2010) indicates that based on consideration of the same pathways of exposure (soil ingestion, dermal contact and inhalation of particulates), health-based guidelines for non-carcinogenic PAHs are at least 10,000 times higher than the BaP guideline. Hence the adoption