Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:2:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 2 (pt 2/7)
Character Range: 2916074–2919343

2009 included:
    * Annex A  alpha hexachlorocyclohexane, beta hexachlorocyclohexane, chlordecone, hexabromobiphenyl, hexabromodiphenyl ether, heptabromodiphenyl ether, lindane, pentachlorobenzene, tetrabromodiphenyl ether, pentabromodiphenyl ether
    * Annex B  perfluorooctane sulfonic acid, its salts and perflurooctane sulfonyl fluoride.
Further consideration of the data available for these chemicals and the potential for developing an HIL will be included in subsequent reviews of the HILs.

HILs have been developed for all POPs adopted in the Stockholm Convention prior to 2009, with the exception of PCDD/PCDF. These chemicals do not have HILs but a contaminated site that has a history suggesting the likely presence of dioxins would require a site-specific health risk assessment (refer Section 12 of Schedule B2).

2.2              Summary of HILs
The HIL values for the four broad land use categories are presented in Table 2. Additional information to assist in the use of the HIL values during a site-specific assessment is presented below.

    2.2.1         Laboratory level of reporting
The available laboratory detection limits should be reviewed in conjunction with the HILs to ensure that the most relevant detection limit is employed and the collection of additional site-specific information (for example, soil vapour data) is appropriate.

    2.2.2         Polycyclic aromatic hydrocarbons
The assessment of the health risk posed by polycyclic aromatic hydrocarbons (PAHs) is complicated by the large number of individual PAHs and the complex mixtures that exist in the environment. A specific HIL value has only been derived for the carcinogenic PAHs, based on the toxicity of benzo(a)pyrene (BaP). For other carcinogenic PAH compounds or carcinogenic PAH mixtures, the toxicity equivalence factor (TEF) approach is recommended. The TEF approach assumes that the risk posed by individual carcinogenic PAHs is additive and proportional to the potency of each compound in the mixture. The potency of individual carcinogenic PAHs is expressed relative to benzo(a)pyrene.

Naphthalene, the most significant volatile PAH, requires separate assessment, as the vapour inhalation pathway is of greater significance. The assessment of potential naphthalene exposures should consider the Health Screening Level (HSL) for naphthalene derived from exposure to petroleum hydrocarbons (Schedule B1).

To apply the HIL to a mixture of carcinogenic PAHs, the concentration of each carcinogenic PAH in the mixture should be multiplied by the respective TEF outlined in Table 1 and the resulting values summed for comparison with the benzo(a)pyrene HIL value.
Table 1. Toxicity equivalence factors for PAHs
PAH                     TEF
Benzo(a)anthracene      0.1
Benzo(a)pyrene          1
Benzo(b+j)fluoranthene  0.1
Benzo(g,h,i)perylene    0.01
Benzo(k)fluoranthene    0.1
Chrysene                0.01
Dibenz(a,h)anthracene   1
Indeno(1,2,3-cd)pyrene  0.1
Source: CCME (2008)

    2.2.3         Toxicity surrogate approach
A number of groups of chemicals addressed in the derivation of the HILs contain a number of similar chemical constituents where there is a mix of information on individual chemicals. In cases where there is insufficient information