Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 2/4)
Character Range: 2591828–2595101

of less significance than ingestion of soil. While likely to be negligible, potential inhalation exposures associated with dust have been considered in the HIL derived.

1.3.4         Plant Uptake
Most chlorophenoxy herbicides are toxic to plants and, as such, will be phytotoxic to almost all broadleaf crops including tomatoes, grapes and fruit trees, well before plant uptake into edible portions of fruit and vegetable crops is of significance. Hence the uptake of these compounds into home-grown produce has not been considered in the derivation of HIL A.

Note that the phytotoxic effects of these compounds may need to be addressed on a site-specific basis if detected in soil.

1.3.5         Intakes from Other Sources – Background
Review of available publications suggests that very little data is available for Australia. Based on the available information on 2,4,5-T and 2,4-D in the environment, it is likely that background intakes by the general public will be similar to those considered for 2,4-D, which can be considered to be essentially negligible (0%).

1.4              Identification of Toxicity Reference Values

1.4.1         Classification
The International Agency for Research on Cancer (IARC 1987) has classified chlorophenoxy herbicides as Group 2B—possibly carcinogenic to humans.

US EPA has not classified 2,4,5-T.

1.4.2         Review of Available Values/Information
Limited data is available on the assessment of carcinogenicity and genotoxicity for 2,4,5-T. Available information on 2,4,5-T is often confounded with the presence of dioxin (TCDD) which was a common contaminant in 2,4,5-T herbicides. 2,4,5-T alone has not been found to be carcinogenic (Joint FAO/UNEP 2005).

On the basis of the available information, it is considered appropriate that a threshold dose-response approach be adopted for 2,4-5-T. The following are available from Level 1 Australian and International sources:
Source              Value                                                                                    Basis/Comments
Australian
ADWG (NHMRC 2011)   TDI = 0.03 mg/kg/day                                                                     Current drinking water guideline of 0.1 mg/L based on 10% intake from drinking water. Based on equations presented in the ADWG (NHMRC 2011), the TDI considered in this derivation is equal to 0.029 mg/kg/day, essentially equivalent to the ADI available from the Joint FAO/WHO. No further information on the basis for this value is available.
OCS (2012)          Deleted from current list in 2003. Prior to this, the ADI was listed as 0.03 mg/kg/day.  Previous ADI referenced from Joint FAO/WHO evaluation from 1981.
International
WHO (1981)          Temporary ADI of 0-0.03 mg/kg/day                                                        Temporary ADI based on a NOEL of 3 mg/kg/day from a rat carcinogenicity study with 2,4,5-T containing 0.05 ppm TCDD.
WHO (2011)          TDI = 0.003 mg/kg/day                                                                    2,4,5-T has been reviewed in the WHO DWG (originally reviewed and established in 1996,) with a TDI of 0.003 mg/kg/day derived based on a NOAEL for reduced body weight gain, increased liver and kidney weights and renal toxicity in a 2 -year