Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:2:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 2 (pt 3/4)
Character Range: 2872717–2875953

background intakes) = 60%
         UFVC = plant uptake factor calculated for the consumption of home-grown produce by young children (kg/day) = 4.4x10-4 kg/day based on Equation 16
         CFy = plant concentration factors relevant for produce type (y), (chemical-specific) (mg/kg fresh weight produce to mg/kg dry weight soil), see table below
    Cy  = consumption rate of each produce type (y) (kg/day), see table below
         FHG = fraction of all fruit and vegetable produce consumed that is home-grown (unitless) = 10% or 0.1 as per Schedule B7
    EF = exposure frequency (days/year) = 365 days per year
    EDC = exposure duration for young children (years) = 6 years
    BWC = body weight of young child (kg) = 15 kg
    ATT = averaging time for threshold contaminants (days, = ED x 365 days) = 2190 days

For cadmium the plant uptake factors, or concentration factors, (CFy) for the different produce types are presented in Appendix A. The consumption rate of each produce type, by young children, is presented in Table 7 in Schedule B7. These are both summarised for cadmium in the following table. These have been used in Equation 16 to calculate the plant uptake factor for young children.

Produce Group     Plant Uptake Factors or Concentration Factors CFy (mg/kg produce fresh weight per mg/kg soil) (EA 2009c)  from Appendix A  Child consumption rate for each produce group (kg/day) – from Table 7 in Schedule B7
Green vegetables  0.052                                                                                                                       0.055
Root vegetables   0.029                                                                                                                       0.017
Tuber vegetables  0.031                                                                                                                       0.028
Tree fruit        0.0014                                                                                                                      0.18

As noted in Appendix A, and the calculation sheets in Appendix C, as background intakes (via ingestion) are dominated by intakes from food sources, the inclusion of uptakes from home-grown produce as well as all other food sources results in some double counting of cadmium intakes via food sources. As discussed in Section 1.3.5 to correct for this double counting, the calculated HIL from plant uptake has been adjusted by a factor of 2-fold (which has the effect of reducing the contribution from this pathway by 50%).
Hence the calculated HIL plant uptake = 21 mg/kg (after rounding)

Calculation of the Residential HIL from all Exposure Pathways

The final HIL is calculated by combining the pathway-specific HILs calculated above using Equation 2 (for the complete pathways of exposure) (as rounded):
   Equation 2

As noted in Appendix A, for cadmium an HIL A of 15 mg/kg has been calculated using the above equations. The value of 15 mg/kg is considered to be essentially the same (with consideration of uncertainties and accuracy of HIL calculations) as the existing HIL of 20 mg/kg. There is no new data available that suggests that the existing HIL is not adequately protective and that, given the