Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:5:p5
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 5 (pt 5/9)
Character Range: 2155057–2157856

D (not classified).

    5.4.2         Review of Available Values/Information
Oral and inhalation exposures have been reviewed separately as follows.

5.4.2.1         Oral Intakes
There is limited data available regarding the carcinogenic potential of ingested Cr VI. Cr VI compounds appear to be genotoxic and some reviews (RIVM 2001) suggest that a non-threshold approach is relevant to all routes of exposure. Some drinking water studies (NTP 2008) are available that show a statistically significant increase in tumours in rats and mice. However, there is currently no peer-reviewed data available to determine a quantitative non-threshold value for ingestion of Cr VI compounds (note a draft value has been recently published by OEHHA 2009). There is also some suggestion (De Flora et al. 1997; Jones 1990) that there may be a threshold for the carcinogenicity of Cr VI based on the hypothesis that it is a high-dose phenomenon, where the dose must exceed the extracellular capacity to reduce Cr VI to Cr III.
The following are available for oral intakes from Level 1 Australian and International sources:
Source              Value                    Basis/Comments
Australian
ADWG (NHMRC 2011)   No evaluation available  The ADWG (NHMRC 2011) does not specifically derive a guideline; however it references the WHO DWG assessment, where the basis for derivation is not clear. No quantitative toxicity values can be obtained from these sources.
International
WHO (2011)          No evaluation available  Current guideline based on limit of detection as no adequate toxicity studies were available to provide the basis for a NOAEL. It is noted that chromium is included in the plan of work of rolling revisions to the DWG WHO (2011).
DEFRA & EA (2002)   TDI = 0.003 mg/kg/day    Adopted oral RfD from the US EPA.
RIVM (2001)         TDI = 0.005 mg/kg/day    RIVM has adopted a provisional threshold TDI of 0.005 mg/kg/day based on a 1-year drinking water study in rats as used in the derivation of the former and current US EPA RfD (with a small difference in the application of uncertainty factors).
ATSDR (2008)        MRL = 0.001 mg/kg/day    The chronic oral MRL is based on a BMDL10 of 0.09 mg/kg/day for non-neoplastic lesions of the duodenum in a 2-year drinking water study in rats and mice (NTP 2008) and an uncertainty factor of 90. The study considered by ATSDR was not available when the other organisations (US EPA, etc.) reviewed Cr VI.
US EPA (IRIS 2012)  RfD = 0.003 mg/kg/day    The US EPA (available on IRIS, but last reviewed in 1998) derived an oral RfD of 0.003 mg/kg/day based on a NOAEL of 2.5 mg/kg/day from a 1-year drinking water study in rats and an uncertainty factor of 300 and modifying factor of 3 to address uncertainties in the study. The confidence level in the