Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:6:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 6 (pt 2/5)
Character Range: 2526612–2529585

absorption
Insufficient data is available on the dermal absorption of heptachlor from soil. Hence the default values of 0.1 (10%) suggested by US EPA (1995) for pesticides has been adopted in the derivation of HILs.

6.3.3         Inhalation of Dust
Heptachlor is not considered sufficiently volatile to be of significance and inhalation exposures associated with particulates outdoors and indoors are expected to be of less significance than ingestion of soil. While likely to be negligible, potential inhalation exposures associated with dust have been considered in the derived HIL.

6.3.4         Plant Uptake
The few studies that are available with respect to the potential for plant uptake of heptachlor relate to the application of the compound in solution (as a product), rather than uptake from soil. Heptachlor and heptachlor epoxide have a high Koc value (log Koc = 3.344.37) and low solubility in water (ATSDR 2007), suggesting that the compound is largely bound to the soil particulates and immobile in soil. For plant uptake to be significant, the chemicals must be able to partition to soil water. With respect to heptachlor bound to soil, the potential for partitioning to soil water is considered to be low and hence plant uptake is considered to be negligible.

6.3.5         Intakes from Other Sources – Background
For the general population, where heptachlor and heptachlor epoxide are no longer used (the last heptachlor product was cancelled by APVMA at the end of June 1997), background intakes would be expected to be primarily associated with residues in food.

Food Standards Australia and New Zealand has not detected heptachlor in any sample in the 19th, 20th or 23rd food surveys (FSANZ 2003; FSANZ 2011). Hence, background intakes would be expected to be negligible. This is consistent with reviews of background intakes estimated by Di Marco (1993), where background intakes from heptachlor (where no longer used) comprises <2% of the adopted ADI.

6.4              Identification of Toxicity Reference Values

6.4.1         Classification
The International Agency for Research on Cancer (IARC 2001) has classified heptachlor as Group 2B—possibly carcinogenic to humans, based on inadequate evidence in humans and sufficient evidence in animals. It is noted that the IARC evaluation is for both chlordane and heptachlor as they are structurally related organochlorine insecticides.

It is noted that US EPA has classified heptachlor as Group B2—probable human carcinogen.

6.4.2         Review of Available Values/Information
Heptachlor has been associated with carcinogenic effects but the mode of action is of prime importance for determining the most appropriate doseresponse approach to adopt for establishing an HIL. The available data (most recently reviewed by WHO 2006) does not suggest that heptachlor is genotoxic and hence a threshold approach is considered appropriate for the derivation of an HIL. Further review of heptachlor