Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p4
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 4/7)
Character Range: 2463104–2466113

fruit and vegetable crops is likely to be of significance. These issues should be assessed on a site-specific basis

1.3.5         Intakes from Other Sources – Background
For the general population, background intakes would be expected to be primarily associated with residues in food, which appear to be slowly disappearing from the food chain (Beard 1993). Background intakes considered in the previous HIL were estimated to be 0.546 mg/kg/day for infants, predominantly derived from dietary sources.

More recent information from Food Standards Australia New Zealand in the 20th Australian Total Diet Survey (FSANZ 2003) indicates that dietary exposures for all age groups was less than 0.2% of the adopted ADI (0.002 mg/kg/day). DDT was not detected in the 23rd Australian Total Diet Survey (FSANZ 2011). On this basis, background intakes can be considered negligible (0%). This evaluation is consistent with that presented by RIVM (2001).

1.4              Identification of Toxicity Reference Values

1.4.1         Classification
The International Agency for Research on Cancer (IARC 1991) has classified DDT and associated compounds as 2B—possible human carcinogens.

The US EPA has classified DDT as B2—probable human carcinogen.

1.4.2         Review of Available Values/Information
While DDT has some carcinogenic potential, the mode of action is important in determining the most appropriate approach to the identification of quantitative toxicity values. No discussion is presented in the profile regarding mode of action and potential for genotoxicity. Review of available information (ATSDR 2002; WHO (2011); RIVM 2001; IARC 1991) suggests that while some conflicting data is available with regard to some genetic end points, DDT and derivatives are not genotoxic (or it is equivocal) and therefore it is not appropriate to consider a non-threshold (linear) doseresponse approach. Hence, it is not appropriate to consider the use of the slope factor and unit risk values available from US EPA.

On the basis of the available information, it is considered appropriate that a threshold doseresponse approach be adopted for DDT. The following are available from Level 1 Australian and International sources:

Source              Value                     Basis/Comments
Australian
ADWG (NHMRC 2011)   TDI = 0.0025 mg/kg/day    The NHMRC derived a guideline of 0.009 mg/L based on a TDI of 0.0025 mg/kg/day. The TDI is derived on the basis of a NOEL of 0.25 mg/kg/day from a 25-year study in humans, and an uncertainty factor of 100 (includes 10 for intraspecies variation and 10 for the uncertainty arising from the lack of detail in the epidemiological study used).
OCS (2012)          TDI = 0.002 mg/kg/day     TDI was set in 2003 (same as previous ADI), based on a NOEL of 0.25 mg/kg/day from studies in humans and experimental animals, and an uncertainty factor of 100.
International
WHO (2011)          PTDI = 0.01 mg/kg/day     Provisional TDI referenced inWHO(2011) was established by JMPR