Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:2:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 2 (pt 3/5)
Character Range: 2771850–2774871

other sources found indoors (from a wide range of common products) are likely to be present and may contribute more significantly to background exposures. These sources need to be addressed on a site-specific basis.

2.5              Identification of Toxicity Reference Values

    2.5.1         Classification
The International Agency for Research on Cancer (IARC 1999) has classified 1,1,1-TCA as Group 3—not classifiable.

Review by US EPA (2007) noted that for 1,1,1-TCA there is 'inadequate information to assess carcinogenic potential'.

    2.5.2         Review of Available Values/Information
There is insufficient data available to determine carcinogenicity of 1,1,1-TCA (WHO 2011, ATSDR 2006 and US EPA 2007). Review by US EPA (2007) has noted that 1,1,1-TCA has been tested extensively for genotoxic potential. The chemical has shown little capacity to produce genotoxic effects in bacteria or fungi. Results in mammalian test systems in vitro and in vivo were more mixed, but still predominantly negative for assays other than cell transformation. The chemical has been shown to interact weakly with DNA. The overall weight of evidence suggests that 1,1,1-TCA is not considered genotoxic.

On the basis of the available information, it is considered appropriate that a threshold doseresponse approach be adopted for 1,1,1-TCA. Few quantitative toxicity values are available but the following are available from Level 1 Australian and International sources:
Source               Value                     Basis/Comments
Australian
ADWG (NHMRC 2011)    No guideline established  No guideline established in current ADWG (NHMRC 2011) due to insufficient data.
International
WHO (2011)           TDI = 0.6 mg/kg/day       No guideline is established as 1,1,1-TCA concentrations in drinking water are well below those of health concern. The review notes that a health-based guideline of 2 mg/L can be derived based on a TDI of 0.6 mg/kg/day based on a NOAEL of 600 mg/kg associated with liver and kidney effects from a short-duration oral study in rats, and an uncertainty factor of 1000.
RIVM (1993)          MPC = 4.8 mg/m3           Maximum permissible concentration (MPC) in air derived on the basis of a duration corrected NOAEL of 482 mg/m3 associated with liver effects in a 2-year rat inhalation study, and an uncertainty factor of 100.
ATSDR (2006)         No chronic MRLs derived
US EPA (IRIS 2012)   RfD = 2 mg/kg/day         Oral reference dose (RfD, last reviewed in 2007) of 2 mg/kg/day derived on the basis of a benchmark approach with a BMDL10 of 2155 mg/kg/day associated with reduced body weight in a 90-day mouse study, and an uncertainty factor of 1000 (including 3 for database deficiencies).
                     RfC = 5 mg/m3             RfC (last reviewed in 2007) derived on the basis of a NOAEL (HEC) of 1553 mg/m3 associated with liver effects in mice and rats, and an uncertainty factor of 100.

In relation to inhalation exposures (the only pathway considered in development of soil