Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 2/14)
Character Range: 2687587–2690420

need to be considered on a site‑specific basis.

Due to the thermal and chemical stability of PCBs, they are widely used as coolants and lubricants in transformers, capacitors and other electrical equipment (ATSDR 2000). In Australia, PCBs were also used in the manufacture of plastics, adhesives, paints and varnishes and were found in consumer products such as pesticides, fluorescent lighting and carbonless copy paper. PCBs were used in Australia between the 1930s and 1970s, when the importation of PCBs was banned.

1.2              Previous HIL
The derivation of the previous HIL (HIL A = 10 mg/kg) for PCBs is presented by Di Marco & Buckett (1993) and NEPC (1999). In summary, the HIL was derived on the basis of the following:
    * Background intakes from air, water and food were estimated to be 5.4 ng/kg/day for a child and 4.4 ng/kg/day for an adult, estimated to be approximately 5% of the adopted PTDI (derived PTDI of 0.0001 mg/kg/day for Aroclor 1016).
    * Due to the lack of published data for PCBs, the lowest threshold value derived for Aroclors 1016 and 1248 were considered. A PTDI of 0.0001 mg/kg/day was derived for Aroclor 1016 based on a NOAEL of 0.0125 mg/kg/day, and a safety factor of 100.
    * Intakes derived from ingestion (assuming 30% bioavailability), inhalation of dust (assuming 50% bioavailability) and dermal absorption (10% absorption) were considered in the derivation of the soil HIL of 10 mg/kg.

1.3              Significance of Exposure Pathways

1.3.1         Oral Bioavailability
Bioavailability of PCBs in soil appears to be important due to their high affinity for soil particles and organic matter. Bioavailability was considered in the derivation of the current HIL (Di Marco & Buckett 1993) with 30% assumed for oral intakes and 50% assumed for inhalation. The basis for this assumption is not available and no more detailed reviewed of PCB bioavailability (oral or inhalation) in soil is available.

Insufficient data is available to adequately define the bioavailability of PCBs in the range of contaminated sites that may need to be considered in Australia. On this basis, a default approach of assuming 100% oral bioavailability has been adopted in the derivation of an HIL. It is noted that a site‑specific assessment of bioavailability can be undertaken where required.

1.3.2         Dermal absorption
US EPA (2004) recommends a dermal absorption value of 0.14 (14%) for PCB Aroclors 1254/1242 and other PCBs, based on a study by Wester et al. (1993). A range of dermal absorption values is presented by ATSDR (2000). Review of these studies suggests that, while the data is limited, the value recommended by US EPA (2004) is adequately representative.

1.3.3         Inhalation of Dust
PCBs are not considered sufficiently volatile to be of significance and inhalation