Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:2:p4
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 2 (pt 4/6)
Character Range: 2480585–2483747

Risk Assessment considered that dieldrin-induced liver tumours occur through a non-genotoxic mode of action. The review also considers that a more appropriate cancer descriptor for aldrin/dieldrin is 'not likely to be carcinogenic to humans'.

On the basis of the available information, it is considered appropriate that a threshold doseresponse approach be adopted for aldrin and dieldrin. The following are available from Level 1 Australian and International sources:
Source                     Value                                                Basis/Comments
Australian
ADWG (NHMRC & NRMMC 2011)  ADI = 0.0001 mg/kg/day                               The ADI available in the ADWG (NHMRC & NRMMC 2011) is noted to be derived from JMPR evaluation (noted to be 1977).
OCS (2012)                 TDI = 0.0001 mg/kg/day                               This value (set in 2003) is based on the JMPR evaluation from 1994 (refer to comment below). The TDI is noted to be retained for comparison against dietary intakes only as these compounds are no longer used in agricultural practice. The ADI listed is also adopted by FSANZ.
International
WHO (2011)                 PTDI = 0.0001 mg/kg/day                              The ADI/PTDI has been considered in the derivation of WHO (2011) based on the JMPR evaluation where the provisional TDI is based on a NOAEL of 1 mg/kg/day in dogs and 0.5 mg/kg/day in rats (dietary studies, Fitzhugh et al. 1964; Fitzhugh & Nelson 1963), which is equivalent to 0.025 mg/kg/day in both species, and application of 250-fold uncertainty factor (10 for interspecies variation, 10 for intraspecies variation and 2.5 for concern about carcinogenicity observed in mice). It is noted that the WHO DWG evaluation has not changed since 1970.
RIVM (2001)                Adopted JMPR evaluation as noted above from WHO DWG
ATSDR (2002)               MRL = 0.00003 mg/kg/day for aldrin                   Chronic oral MRLs for aldrin and dieldrin based on a LOAEL of 0.025 mg/kg/day associated with liver effects in rats and application of 100-fold uncertainty factor. Values adopted are consistent with those available from the US EPA (IRIS 2012).
                           MRL = 0.00005 mg/kg/day for dieldrin
US EPA (IRIS 2012)         RfD = 0.00003 mg/kg/day for aldrin                   RfD for aldrin based on a LOAEL of 0.025 mg/kg/day associated with liver toxicity in a chronic rat study (Fitzhugh et al. 1964) and application of a 1000-fold uncertainty factor. The evaluation was last reviewed in 1988.
                           RfD = 0.00005 mg/kg/day for dieldrin                 RfD for dieldrin based on a NOAEL of 0.005 associated with liver lesions in a 2-year rat study and a 100-fold uncertainty factor. The review was last updated in 1990.
                                                                                In addition the US EPA has also derived non-threshold values for aldrin and dieldrin. It is not considered appropriate to quantify aldrin and dieldrin toxicity on the basis of a non-threshold approach.

All the key studies considered in the above reviews are dated (in the 1960s) and no new studies