Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 2/5)
Character Range: 2504213–2507105

available to adequately define the bioavailability of endosulfan 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.

4.3.2         Dermal absorption
Insufficient data is available on the dermal absorption of endosulfan 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.

4.3.3         Inhalation of Dust
Endosulfan 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 HIL derived.

4.3.4         Plant Uptake
The few studies that are available with respect to the potential for plant uptake of endosulfan relate to the application of endosulfan in solution, rather than uptake from soil. Endosulfan has a high Koc value (log Koc = 3.5) and low solubility in water (ATSDR 2000), suggesting that the compound is largely bound to 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 endosulfan bound to the soil, the potential for partitioning to soil water is considered to be low and hence plant uptake is considered to be negligible.

4.3.5         Intakes from Other Sources – Background
Background intakes have been assessed by Marshall & Rutherford (2003) on the basis of available Australian data. For a 2-year-old child, background intakes (from air, food and water) were estimated to contribute 7% of the ADI adopted (0.006 mg/kg/day). However, it has been noted that this evaluation was based on limited data and a default approach of considering 80% background intakes was adopted.

Background exposure by the general public is expected to be dominated by food residue intakes in areas away from where endosulfan products are being applied. Food Standards Australia and New Zealand has reported that intakes of endosulfan by all age groups was less than or equal to 2% of the adopted ADI in the 23rd Australian Total Diet Study (FSANZ 2011). The National Estimated Daily Intake of endosulfan was reviewed by APVMA (2005) and estimated to be equivalent to 27% of the recommended oral TRV (0.006 mg/kg/day), which is more conservative that the current dietary survey indicates. On this basis a background intake of 30% is considered appropriate for deriving a soil HIL for endosulfan.

4.4              Identification of Toxicity Reference Values

4.4.1         Classification
The International Agency for