Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 1/5)
Character Range: 2501278–2504467

4                   Endosulfan (total)

4.1              General
Several comprehensive reviews of endosulfan in the environment and its toxicity to humans are available and should be consulted for more detailed information (ATSDR 2000; APVMA 2005; Marshall & Rutherford 2003; WHO 1984). The following provides a summary of the key aspects of endosulfan that are relevant to the derivation of a soil HIL.

Endosulfan is the common name for an organochlorine pesticide which predominantly contains the compound 6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepine-3-oxide. The manufacture of endosulfan yields two stereo-isomers denoted as α-endosulfan and β-endosulfan in a ratio of 7:3. Technical grade endosulfan generally comprises 94% total endosulfan (α-endosulfan and β-endosulfan) with the remainder comprising impurities and degradation products such as endosulfan ether, endosulfan alcohol and endosulfan sulfate (ATSDR 2000). Endosulfan insecticides are produced under the following trade names; Thiodan; Thionex; Thionate Malix; HOE 2671; FMC 5462; Cyclodan; Thifor; Beosit; Chlorthiepin and Endocide (ATSDR 2000).

Endosulfan is a cream to brown-coloured crystalline solid or waxy solid with a distinct turpentine-like odour. It has a low solubility in water, a low vapour pressure and does not burn (ATSDR 2000). The β-isomer is more chemically stable than the α-isomer, which slowly transforms to the β-isomer in the environment (ATSDR 2000).

Endosulfan is manufactured and used as a broad-spectrum insecticide to control insects on horticultural and agricultural products such as grains, tea, fruits, vegetables, tobacco and cotton. It is manufactured worldwide for commercial agricultural use and domestic (home gardening) use. Endosulfan is also used as a wood preservative (ATSDR 2000). Endosulfan was registered for commercial use in Australia in the 1970s until its deregistration in October 2010 with a two-year phase-out until October 2012. Prior to the late 1990s, when restrictions on its use were introduced, approximately 900 tonnes of technical grade endosulfan was imported annually into Australia. Its use significantly decreased in the years leading up to its deregistration. It was primarily used in cotton production (70%), followed by vegetables (20%) and other crops and horticultural products (10%) (APVMA 2005). Both isomers of endosulfan and endosulfan sulphate were added to the Stockholm Convention in April 2011.

4.2              Previous HIL
No previous HIL is available (NEPC 1999), though it is noted that review of endosulfan by Marshall & Rutherford (2003) suggested a soil guideline value of 160 mg/kg may be derived (assuming 20% of ADI is derived from soil, 100% bioavailability and soil ingestion is the most significant pathway of exposure).

4.3              Significance of Exposure Pathways

4.3.1         Oral Bioavailability
Insufficient data is 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