Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 1/5)
Character Range: 2488815–2491755

3                   Chlordane (total)

3.1              General
Several comprehensive reviews of chlordane in the environment and its toxicity to humans are available and should be consulted for more detailed information not presented in this summary (ATSDR 1994). The following provides a summary of the key aspects of chlordane that are relevant to the derivation of a soil HIL.

Chlordane is a manufactured chemical that does not occur naturally in the environment. It is a thick liquid, and the colour ranges from colourless to amber depending on its purity. Chlordane does not dissolve in water but can be produced as an emulsion enabling it to be sprayed (ATSDR 1994). Sixty to eighty-five percent of chlordane consists of the stereo-isomers cis- and trans-chlordane, with the remainder comprising a number of impurities (ATSDR 1994).

Chlordane is a manufactured chemical that was used as a broad-spectrum insecticide in the United States between 1948 and 1988 (ATSDR 1994). In Australia, it was used to protect wooden structures against termites until June 1995 (NHMRC 2011). Some of its trade names are Octachlor and Velsicol 1068.

3.2              Previous HIL
The derivation of the previous HIL (HIL A = 50 mg/kg) for chlordane is presented by Di Marco (1993) and NEPC (1999). In summary, the HIL was derived on the basis of the following:
    * Background intakes were considered in the derivation of the current HIL with the intakes from food, water and ambient air considered to comprise 40% of the adopted ADI.
    * An ADI of 0.0005 mg/kg/day, referenced from the JMPR, was considered. An additional factor of 3 was used because of the uncertainties associated with the bioavailability estimates adopted and exposure levels in the future.
    * Dermal absorption of organochlorine pesticides was considered to be 5%.
    * Oral bioavailability of organochlorine pesticides was considered to be 10%.
    * Based on intakes derived from soil (ingestion, dermal absorption and dust inhalation), an HIL of 50 mg/kg was calculated.

3.3              Significance of Exposure Pathways

3.3.1         Oral Bioavailability
Insufficient data is available to adequately define the bioavailability of chlordane in the range of contaminated sites that may need to be considered in Australia. On this basis, a default approach of assuming 100% oral bioavailability has been adopted in the derivation of an HIL. It is noted that a site-specific assessment of bioavailability can be undertaken where required.

3.3.2         Dermal absorption
US EPA (2004) has identified a dermal absorption fraction of 0.04 (4%), based on a study by Wester et al. (1992) for chlordane in soil. No additional data is available to suggest more significant dermal absorption values are relevant for chlordane.

3.3.3         Inhalation of Dust
Chlordane is not considered sufficiently volatile to be of significance and inhalation exposures associated with