Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:7:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 7 (pt 2/5)
Character Range: 2539257–2542234

of HCB relate to the application of the product in solution (as a product), or from fresh applications where some volatilisation has occurred (not considered relevant where HCB products are no longer used), rather than uptake from soil. HCB has a high Koc value (log Koc = 3.596.08) and low solubility in water (ATSDR 2002), suggesting that the compound is largely bound to the soil particulates and is immobile in soil. For plant uptake to be significant, the chemicals must be able to partition to soil water. With respect to HCB bound to the soil, the potential for partitioning to soil water is considered to be low and hence plant uptake is considered to be negligible.

7.3.5         Intakes from Other Sources – Background
For the general population, away from areas where significant stores of HCB waste have been identified (refer to HCB Waste Management Plan, ANZECC 1996), background intakes would be expected to be primarily associated with residues in food.

Food Standards Australia and New Zealand has not detected HCB in any sample in the 18th, 19th or 20th food surveys (FSANZ 2003). WHO (1997) calculated that the total background intake by an adult of HCB is between 0.0004 and 0.003 µg/kg body weight per day, mostly derived from dietary exposures. This intake is essentially negligible compared to the recommended oral TRV. Hence, background intakes would be expected to be negligible. This is consistent with reviews of background intakes estimated by RIVM (2001).

7.4              Identification of Toxicity Reference Values

7.4.1         Classification
The International Agency for Research on Cancer (IARC 2001) has classified HCB as Group 2B—possibly carcinogenic to humans, based on inadequate evidence in humans and sufficient evidence in animals.

HCB has been classified as a probable human carcinogen (Category B2) by US EPA on the basis of the induction of tumours in the liver, thyroid and kidney in three rodent species following oral exposure.

7.4.2         Review of Available Values/Information
HCB has been associated with carcinogenic effects however; the mode of action is of prime importance for determining the most appropriate doseresponse approach to adopt for establishing an HIL. The available data (WHO DWG 2011; WHO 1997; RIVM 2001) shows that the weight of evidence does not suggest that HCB is genotoxic and hence a threshold approach is considered appropriate for the derivation of an HIL. Further review of HCB by WHO (1997) considered the derivation of a threshold TDI based on both non-neoplastic and neoplastic effects (similar threshold values), hence appropriate threshold values are available that adequately address neoplastic (carcinogenic) effects.

The following are available from Level 1 Australian and International sources:
Source              Value                         Basis/Comments
Australian
ADWG (NHMRC 2011)   No evaluation available
OCS (2012)          No evaluation available
International
JMPR