Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p4
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 4/5)
Character Range: 2119043–2122357

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 boron in drinking water on the basis of a TDI of 0.16 mg/kg/day, based on a NOAEL from a developmental rat study (Price et al. 1996) and an uncertainty factor of 60.
International
WHO (1998)          TDI = 0.4 mg/kg/day      The WHO (1998) review derived a TDI of 0.4 mg/kg/day based on the same study considered in the ADWG (NHMRC 2011) and a different uncertainty factor of 25.
WHO DWG (2009)      TDI = 0.17 mg/kg/day     TDI adopted is consistent with that adopted in the ADWG (NHMRC 2011) and is based on a benchmark dose (BMD) derived from relevant developmental studies of 10.3 mg/kg/day and uncertainty factor of 60. The principal study (noted to be similar to Price et al. 1996) and evaluation is consistent with that presented in the US EPA review (note the US EPA rounded the TDI in its evaluation).
ATSDR (2010)        No evaluation available
US EPA (IRIS 2012)  RfD = 0.2 mg/kg/day      RfD (last reviewed in 2004) based on a BMD of 10.3 mg/kg/day associated with developmental effects in rats and an uncertainty factor of 66.

The ADI currently considered in the ADWG (NHMRC 2011) and by US EPA (2004b) and WHO (2011) are essentially the same value (from studies that have resulted in consistent evaluations), namely 0.2 mg/kg/day. This threshold value is therefore recommended for derivation of the HIL.

No inhalation specific studies or data are available. For the presence of boron in soil it is considered appropriate to consider use of the available TDI for all pathways of exposure.

    3.4.3         Recommendation
On the basis of the discussion above, the following toxicity reference values (TRVs) have been adopted for boron in the derivation of HILs:

3.5              Calculated HILs
On the basis of the above, the following HILs have been derived for boron (refer to Appendix B for equations used to calculate the HILs and Appendix C for calculations):
HIL Scenario            HIL (mg/kg)                      Percentage Contribution from Exposure Pathways
Ingestion of Soil/Dust  Ingestion of Home-grown Produce  Dermal Absorption of Soil/Dust                  Inhalation (dust)
Residential A           4500                             100                                             Included in background  --  <1
Residential B           40 000                           100                                             --                      --  <1
Recreational C          20 000                           100                                             --                      --  <1
Commercial D            300 000                          100                                             --                      --  <1

-- Pathway not included in derivation of HIL

3.6              References
ATSDR, 2010, Toxicological Profile for Boron, Agency for Toxic Substances and Disease Registry. Available from http://www.atsdr.cdc.gov/ToxProfiles/tp.asp?id=453&tid=80.
Mangas, S 1998, 'Derivation of Health Investigation Levels for Boron and Boron Compounds', presented in the proceedings of