Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 3/5)
Character Range: 2116382–2119332

was to consider potential intakes associated with consumption of home-grown produce in soil concentrations that are not phytotoxic (300 mg/kg), as part of the overall intake from other sources. To obtain the additional background intake, a child's produce consumption (0.048 kg DW[1]/day) was multiplied by 300 mg/kg and divided by the child body weight of 15.5 kg to obtain the maximum additional background daily intake for 100 % of produce being home-grown. For the consumption of 10% home-grown produce, this results in an additional intake of 0.09 mg/kg/day being considered.

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). Hence background intakes that may be derived from all sources, including home-grown produce, are estimated to be 0.17 mg/kg/day.

    3.3.5         Intakes from Other Sources – Background
No data is available on intakes of boron from sources other than soil in Australia. Hence the assessment of potential intakes from these sources has considered available international data.

Reviews of boron (WHO 1998 and ATSDR 2010) suggest that mean intakes of boron from the diet are approximately 1.2 mg/day for adults (and 0.85 mg/day for children), with intakes from consumer products approximately 0.1 mg/day (WHO 1998) and the contribution from air negligible. The total background intake presented by WHO (1998) is 1.9 mg/day. If this intake were assumed relevant for young children, it would comprise 0.13 mg/kg/day for young children. This is slightly higher than that estimated by MfE (2011), where intakes were estimated to be 0.08 mg/kg/day for young children (based on the same databut intakes from water were considered to be lower, based on the available water quality data from New Zealand). The higher value of 0.13 mg/kg/day has been adopted in the derivation of a soil HIL.

3.4              Identification of Toxicity Reference Values

    3.4.1         Classification
The International Agency for Research on Cancer (IARC) has not evaluated boron due to inadequate data.

    3.4.2         Review of Available Values/Information
Available studies on genotoxicity (US EPA 2004b and WHO 2009) were negative. This is consistent with the review presented by Mangas (1998). On the basis of the available information, it is recommended that a threshold approach be adopted for the derivation of an HIL for boron in soil.  The following are available from Level 1 Australian and International sources:
Source              Value                    Basis/Comments
Australian
ADWG (NHMRC 2011)   TDI = 0.16 mg/kg/day     The ADWG (NHMRC 2011) derived a guideline for