Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 3/4)
Character Range: 2809453–2812507

(2011) provided equivocal results. Review by RIVM (2001) suggested that cis-1,2-DCE could be considered genotoxic in vivo, producing gene mutations and chromosome aberrations. However, no carcinogenic toxicity values have been derived for the cis- isomer. A more recent review of genotoxicity provided by US EPA (2010) suggested that, overall, data for 1,2-DCE (both isomers) is not positive for genotoxicity and mutagenicity. The positive results (considered by RIVM) are considered inconsistent by US EPA and need further confirmation.  On the basis of the available information, it is considered appropriate that a threshold doseresponse approach be adopted for DCE. Few quantitative toxicity values are available; however, the following are available from Level 1 Australian and International sources:
Source             Value                                    Basis/Comments
Australian
ADWG (NHMRC 2011)  TDI = 0.017 mg/kg/day for trans- isomer  The Australian Drinking Water Guidelines (NHMRC 2011) have derived a drinking water guideline of 0.06 mg/L for 1,2-DCE (both isomers) following guidance from WHO (refer below).
International
WHO (2011)         TDI = 0.017 mg/kg/day for trans- isomer  WHO (2011) has derived a guideline of 0.05 mg/L based on a TDI of 0.017 mg/kg/day associated with a NOAEL of 17 mg/kg from a 90-day study in mice administered trans-1,2-DCE in drinking water, and an uncertainty factor of 1000. This guideline is relevant to the sum of both cis- and trans- isomers, however this is due to WHO adopting a conservative approach where there is no data available for the derivation of a cis- isomer value.
RIVM (2001)        TDI = 0.006 mg/kg/day                    A TDI of 0.006 mg/kg/day has been established for cis-1,2-DCE based on a NOAEL of 32 mg/kg/day from a 90-day oral rat study (using the cis- isomer), and an uncertainty factor of 5000.
                   TC = 0.03 mg/m3                          Inhalation tolerable concentrations (TC) were derived for cis-1,2-DCE using route extrapolation from the oral study, resulting in a TC of 0.03 mg/m3
ATSDR (1996)       No chronic MRLs derived
US EPA (2010)      RfD = 0.002 mg/kg/day for cis- isomer    RfD derived on the basis of a BMDL10 of 5.1 mg/kg/day associated with increased kidney weight in male rats and a 3000-fold uncertainty factor (includes 3-fold factor for database deficiencies). No inhalation RfC was derived for the cis-isomer.
                                                            For the trans-isomer an oral RfD of 0.02 mg/kg/day was derived and no inhalation RfC was derived.

For the assessment of inhalation exposures (relevant to the derivation of soil vapour Interim HILs), there are no specific TRVs derived from inhalation studies associated with cis-1,2-DCE. An inhalation value can be derived from route extrapolation from an oral value (as undertaken by RIVM). In relation to the available oral TRVs, the most recent evaluation conducted by US EPA is considered the most appropriate. From this oral TRV, an inhalation TRV of