Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:10:p4
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 10 (pt 4/11)
Character Range: 2244844–2247718

of produce. The recommendations from this review have been considered in the derivation of a residential A HIL and are summarised below for the range of crops considered:
Produce Group     Plant Uptake Factors (mg/kg produce fresh weight per mg/kg soil) (EA, 2009)
Green vegetables  0.0038
Root vegetables   0.0069
Tuber vegetables  0.0042
Tree fruit        0.001

 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).

No plant uptake values are reviewed or recommended for methyl mercury. EA (2009) notes that methylated mercury compounds are likely to be more toxic to plants compared with ionic forms, though no specific data is provided. Review by US EPA (1997) suggests that methyl mercury complexes in soil are available for plant uptake and translocation. In addition, plants have some mercury methylation ability and hence the percentage of methyl mercury in plants may not originate from methyl mercury uptake from soil. Due to the level of uncertainty involved in the estimation of plant uptake of methyl mercury from soil, including the potential for phytotoxicity, it is expected that the conservative approach to the consideration of intakes from dietary sources adequately addresses potential intakes that may be derived from the consumption of 10% home-grown produce.

    10.3.5     Intakes from Other Sources – Background
For inorganic mercury, review of current information from Australia indicates the following:
    * Mercury levels are reported in the 20th Australian Total Diet Survey (FSANZ 2003). Dietary intakes of total mercury (which includes organic mercury in seafood) ranged from 0.010.2 µg/kg/day for toddlers (aged 2 years). This is consistent with intakes reported in the more recent survey (FSANZ 2011).
    * Typical concentrations of mercury reported in the ADWG (NHMRC 2011) are less than 0.0001 mg/L, resulting in an intake (1 L/day and body weight of 15.5 kg) by toddlers of 0.0073 µg/kg/day.
    * Review (NHMRC 1999) of intakes associated with amalgam fillings in Australian children and adults (based on average number of fillings of 0.5 and 8 respectively) provides an reasonable estimate of daily mercury absorption per person of about 0.3 µg for children and 3.5 µg for adults. The estimate for children is expected to be conservative as the use of mercury dental amalgams is declining.
    * Based on the above, background intakes by young children may be up to 0.23 µg/kg/day from oral intakes (dietary, dental and water). This is slightly higher than intakes of 0.1 µg/kg/day