Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:5:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 5 (pt 3/9)
Character Range: 2149995–2152798

the presence of human sweat (Horowitz & Finley 1993, cited in ATSDR 2008), suggesting that soil concentrations up to 50  000 mg/kg may not elicit an allergic response.
    * As allergic contact dermatitis is an inflammatory response mediated by the immune system, this suggests that at least some chromium is absorbed through the skin. Studies that have investigated this response typically express dermal absorption as a function of skin surface area or flux, and thus are difficult to express as a percentage absorbed over time.
    * It is recommended that the adverse effects arising from dermal exposure are considered separately from those arising from oral exposure and that allergic contact dermatitis is the main effect of interest, for which a soil guideline value could be established. However, it is likely that a soil guideline value protective of effects arising from oral exposure will also be protective against allergic contact dermatitis.
It is noted that based on the review presented by Soong & Emmett (1993), the HIL derived on the basis of oral intakes was shown to be adequately protective of allergic contact dermatitis. On the basis of this approach, dermal absorption has been considered negligible for Cr VI, consistent with the approach adopted by MfE (2011).

    5.3.3         Inhalation of Dust
Cr VI 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.

    5.3.4         Plant Uptake
Review of plant uptake by MfE (2011) has noted that concentrations of chromium in a form that can be taken up by plants is extremely low in most soils, consistent with the available data., The approach adopted by MfE (2011) has been to adopt an arithmetic average of plant uptake values available from available reviews that relate to Cr VI and Cr in general (0.0324 mg/kg fresh produce per mg/kg soil). There is limited data available on concentrations of Cr VI in edible fruit and vegetable crops and uptake is expected to be limited. In addition ATSDR (2008) has noted that translocation of chromium within plants is poor. Hence the plant uptake value recommended by MfE (2011) has been considered for root and tuber crops only.

It is noted that the inclusion of home-grown produce in the calculations presented for HIL A results in some double counting of intakes from fruit and vegetable produce (also included in background intakes). To address this in the derivation of HIL A, half the intake estimated to be derived from home-grown produce is assumed to be already accounted for in the total background intake (noted below).

    5.3.5         Intakes