Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:7:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 7 (pt 3/5)
Character Range: 2541864–2544749

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                ADI =0.0006 mg/kg/day         An ADI of 0.0006 mg/kg/day was estimated for HCB by JMPR in 1969 (reaffirmed in 1974) based on a dietary study in rats.
WHO (2011)          TDI = 0.00016 mg/kg/day       No guideline has been established by WHO, as concentrations of HCB occur in drinking water well below those of health concern. However the review conducted (in 2003) has indicated a health-based guideline of 0.0005 to 0.001 mg/L can be derived on the basis of a linear multistage low-dose extrapolation model or a TDI of 0.00016 mg/kg/day.
WHO (1997)          TDI = 0.00016 mg/kg/day       TDI presented is the lowest TDI derived on the basis of non-neoplastic and neoplastic effects. A TDI of 0.00017 mg/kg/day was derived on the basis of a NOEL of 0.05 mg/kg/day associated hepatic effects in pigs and rats, and an uncertainty factor of 200 (the evaluation presented included consideration of the study used by ATSDR in the derivation of the chronic MRL). The lower TDI presented was derived on the basis of a Tumorigenic Dose (TD5) associated with a 5% excess incidence in tumours in experimental animals. The TDI was derived on the basis of results from a 2-generation study in rats where the TD5 values ranged from 0.81 mg/kg/day to 2.01 mg/kg/day. The lower value associated with neoplastic effects in the liver was adopted with an uncertainty factor of 5000 to derive the TDI of 0.00016 mg/kg/day.
                                                  It is noted that review also derived a TDI for non-neoplastic effects of 0.00017 mg/kg/day based on a NOEL of 0.05 mg/kg/day based on hepatic effects in a subchronic study in pigs and a chronic study in rats. This evaluation considered the same studies as ATSDR and US EPA and the non-neoplastic TDI is similar to that derived for neoplastic effects.
ATSDR (2002)        Oral MRL = 0.00005 mg/kg/day  Chronic oral MRL derived on the basis of a LOAEL of 0.016 mg/kg/day for peribiliary lymphocytosis and fibrosis of the liver in a 2-generation study on rats, and an uncertainty factor of 300. The ATSDR review has considered the same study as the US EPA (Arnold et al. 1985), however they have applied slightly different uncertainty factors to the NOAEL.
US EPA (IRIS 2012)  RfD = 0.0008 mg/kg/day        Oral RfD (last reviewed in 1988) based on a NOAEL of 0.08 mg/kg/day associated with liver effects in a rat study, and an uncertainty factor of 100. The US EPA has also derived non-threshold oral and inhalation values which are not presented