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 1/4)
Character Range: 2804066–2807065

4                   Cis-1,2-Dichloroethene (DCE)

4.1              General
Several comprehensive reviews of cis-1,2-dichloroethene (DCE) in the environment and its toxicity to humans are available and should be consulted for more detailed information (ATSDR 1996; WHO 2011). The following provides a summary of the key aspects of DCE that is relevant to the derivation of interim HILs.

DCE is a colourless, volatile and flammable liquid with a characteristic sharp, harsh odour. It is one of two isomers of 1,2-DCE, the second being trans-1,2-DCE. cis-1,2-DCE is considered to be more toxic than trans-1,2-DCE and hence the HILs derived for the cis-isomer are adequately protective of exposures associated with the trans-isomer.

DCE is not known to occur naturally. It is most commonly used as a chemical intermediate to produce chlorinated solvents and chemical compounds. It is also used in rubber extraction, pharmaceutical manufacturing, as a refrigerant and in the extraction of oils from meats and fish. DCE has also historically been used as a solvent for a variety of waxes, resins, perfumes, dyes, lacquers, acetyl cellulose, thermoplastics and phenols (ATSDR 1996).

4.2              Previous HIL
No previous HIL is available for DCE (NEPC 1999).

4.3              Proposed Interim HIL
Review of available information in relation to the presence of DCE in soil indicates that the vapour inhalation pathway is the most significant/important. This pathway should be assessed on the basis of measured vapour data, in particular, soil vapour data. There are significant limitations in the derivation of a soil HIL, in particular, the modelling of phase partitioning from soil to soil vapour and the field measurement of volatiles in soil. Hence, an interim HIL has been derived for soil vapour only.

The following presents the values adopted for the calculation of a soil vapour interim HIL. In addition, other information that is relevant to the assessment of DCE in soil (relevant to other pathways of exposure) is presented.

4.4              Significance of Exposure Pathways

    4.4.1         Inhalation
DCE is a volatile compound and, as such, the derivation of the HIL has considered the vapour inhalation pathway. The approach adopted for the quantification of potential vapour migration to outdoor air and intrusion indoors is outlined in Schedule B7. It is noted that the derived HIL is dominated by the assessment of these pathways of exposure. Due to limitations with the vapour modelling approach, adopted the HILs derived are considered interim.

The inhalation of particulates outdoors and indoors is considered essentially insignificant, compared with vapour inhalation.

    4.4.2         Dermal absorption
Insufficient data is available on the dermal absorption of DCE from soil. Given the volatility of the compound, dermal absorption is expected to be low though, as there is insufficient data available to further assess dermal absorption from soil, a default value of