Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:7:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 7 (pt 2/6)
Character Range: 2185583–2188588

as an additional safety factor of 10 to provide a margin of safety, as there is the likelihood of greater intakes of copper from drinking water in many households. The HIL derived was considered preliminary.

7.3              Significance of Exposure Pathways
Ingestion of soil and dust is considered the most significant pathway of exposure for inorganics in soil. The consideration of bioavailability and inclusion of other exposure pathways in the derivation of a soil HIL has been further reviewed as noted below:

    7.3.1         Oral Bioavailability
Bioavailability has not been considered in the previous HIL, as insufficient data is available to adequately define the bioavailability of copper from soil. On this basis, a default approach of assuming 100% oral (and inhalation) 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.

    7.3.2         Dermal absorption
Review of dermal absorption by MfE (2011) indicated the following with respect to copper: 'Organometallic copper salts are indicated to penetrate the skin, producing anti-inflammatory and anti-arthritic activity (Guy et al. 1999), but limited quantitative dermal absorption data is available. The available data indicates permeability coefficients for copper as copper chloride and copper sulphate are in the order of 0.013 × 10-4 to 0.16 × 10–4 cm/h after 72 h. Although higher permeability coefficients are observed during initial exposures they decrease over the time of exposure (Guy et al. 1999). While this data provides an indication of dermal absorption of copper, they are not readily amenable to expression as a skin absorption factor. Further, in these studies the copper salts were applied in petroleum, aqueous gels or emulsions; it is likely that lower absorption/permeability coefficients would be observed for copper present in contaminated soil. Finally, all the agencies considered in this report that have developed soil guideline values for copper (Canada, The Netherlands, US) have considered dermal exposure to copper to be negligible (NCSRP 1995; Baars et al. 2001; US EPA 2003).' Consistent with the above, dermal absorption of copper has been considered to be negligible.

    7.3.3         Inhalation of Dust
Copper is not volatile and inhalation exposures associated with particulates outdoors and indoors are expected to be of less significance than ingestion of soil. While likely to be negligible, potential inhalation exposures associated with dust have been considered in the HIL derived.

    7.3.4         Plant Uptake
Copper is a micronutrient required by plants for metabolism. Plant growth is affected by copper deficiency as well as toxicity associated with excess levels of copper. The potential for plant uptake and toxicity will be dependent on the form present. Review by MfE (2011) notes that copper is phytotoxic at relatively low tissue concentrations and plant uptake will be