Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:8:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 8 (pt 2/4)
Character Range: 2551684–2554664

to be negligible.

8.3.5         Intakes from Other Sources – Background
No data is available regarding background concentrations of methoxychlor in Australia. The 23rd Australian Total Diet Study (FSANZ 2011) did not detect methoxychlor in any products sampled and tested. US data is available for dietary intakes, but as methoxychlor is not used in Australia and is generally not persistent in the environment, background intakes can be assumed to be essentially negligible.

8.4              Identification of Toxicity Reference Values

8.4.1         Classification
The International Agency for Research on Cancer (IARC 1987) has classified methoxychlor as Group 3—not classifiable.
It is noted that US EPA has classified methoxychlor as Class D—not classifiable.

8.4.2         Review of Available Values/Information
Review of methoxychlor by the WHO (2011) and ATSDR (2002) indicates that recent data (considered inadequate to be conclusive) suggests some carcinogenic potential for methoxychlor for liver and testis in mice, which may be due to the hormonal activity of progestogenic metabolites and may therefore have a threshold. It is noted that methoxychlor is a suspected endocrine disruptor. The review undertaken by ASTDR (2002) considered available genotoxicity studies, with most showing negative results. Hence the genotoxic potential of methoxychlor appears to be negligible (WHO 2011). On this basis, it is appropriate that a threshold approach be adopted. The following are available from Level 1 Australian and International sources:
Source              Value                        Basis/Comments
Australian
ADWG (NHMRC 2011)   TDI = 0.09 mg/kg/day         A health-based guideline of 0.3 mg/L is presented in the ADWG (NHMRC 2011). While no further information is available, based on the assumptions adopted in the ADWG (10% intake from drinking water, 2 L/day and 70 kg body weight), the guideline was derived from a TDI of 0.09 mg/kg/day.
OCS (2012)          TDI = 0.1 mg/kg/day          TDI (set in 2003, changed from the ADI of the same value), noted to be based on the JMPR evaluation. It is noted that methoxychlor is no longer used in Australia and hence the TDI is maintained to address potential dietary intakes.
International
JMPR (1977)         ADI =0.1 mg/kg/day           The ADI of 0.1 mg/kg/day was established in 1963, reviewed and confirmed in 1965 and 1977 based on a NOEL of 10 mg/kg/day in a dietary rat study, and an uncertainty factor of 100.
WHO (2011)          TDI = 0.005 mg/kg/day        A guideline of 0.02 mg/L (last reviewed in 2003) has been derived on the basis of a TDI of 0.005 mg/kg/day from a NOAEL of 5 mg/kg/day associated with a teratology study in rabbits, and an uncertainty factor of 1000 (including a 10 fold factor to address concern for threshold carcinogenicity and the limited database). Methoxychlor is noted to be included in the rolling revision of the WHO DWG. No revised evaluations are currently available.