Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:12:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 12 (pt 3/7)
Character Range: 2297444–2300668

(average of 0.2 ng/m3). These concentrations are lower than those reported in EA (2009a). Based on the mean concentration reported in Australian air, intake by young children is approximately 0.15 ng/kg/day, significantly less than intakes from food and water.
    * Based on the above, background intakes by young children are estimated to be 3 µg/kg/day, approximately 60% of the recommended TRV.

12.4          Identification of Toxicity Reference Values

    12.4.1     Classification
The International Agency for Research on Cancer (IARC 1987) has classified selenium as Group 3—not classifiable.

It is noted that US EPA has classified selenium as Group D—not classifiable.

    12.4.2     Review of Available Values/Information
Insufficient information is available to adequately assess selenium for carcinogenicity. Review by CCME (2007) notes that the available carcinogenicity studies with selenates, selenites and organic selenium compounds have shown negative results. The only selenium compound found to be carcinogenic to experimental animals is selenium sulphide, noted to be not readily present in food and the environment.  Selenium supplementation has been shown to significantly inhibit tumours induced by chemicals, viruses and UV radiation.

Reviews on genotoxicity are mixed. Review by CCME (2007) and ATSDR (2003) suggests the available data on genotoxicity of selenium compounds is inconclusive, with studies showing inorganic selenium compounds having both genotoxic and anti-genotoxic effects, with anti-genotoxic effects generally occurring at lower exposure levels than the genotoxic effects. Review by EA (2009a) suggests that some selenium compounds have given indications of genotoxic effects when administered orally to laboratory animals. However, there is evidence that selenium compounds have given rise to genotoxicity by the production of reactive oxygen species; thus, it has been concluded that the genotoxic effect of selenium is likely to have a threshold.

On the basis of the available information, the consideration of a threshold approach for the quantification of selenium intakes is considered reasonable. It is noted that since selenium is an essential element, a number of the threshold values available are associated with recommended dietary intakes (RDIs) or adequate intake (AI) and associated upper limits (ULs) based on available studies. It is noted that in reviewing the available information, threshold values such as ADIs or RfDs should lie between the RDI or AI and the UL established for selenium intakes. ADIs or RfDs that are lower than the RDI or AI are considered overly conservative and may lead to deficiency. The following provides a summary of quantitative values are available from Level 1 Australian and International sources:
Source               Value                                                                                                       Basis/Comments
Australian
ADWG (NHMRC 2011)    ADI = 0.24 mg/day or 0.003 mg/kg/day for 70 kg adult                                                        The ADWG (NHMRC 2011) derived a health-based guideline of 0.01 mg/L based on an ADI of 0.24 mg/day derived from review of toxic effects from a