Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:12:p5
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 12 (pt 5/7)
Character Range: 2303478–2306391

human health and selenium compounds do not appear to be carcinogenic, the ULs for all life stage groups are proposed for use in the derivation of the human health soil quality guidelines for selenium. The UL noted here is the lower value relevant to infants (the most sensitive age group).
EA (2009a)           UL = 0.45 mg/day or 0.006 mg/kg/day for a 70 kg adult                                                       A Safe Upper Level of 450 μg of total selenium ('ionic selenium') per day was established. This was derived from a LOAEL of 910 μg Se day-1 for mild signs of selenosis (changes in the hair and nails) indicated in an exposed Chinese population, and the use of an uncertainty factor (UF) of 2 to convert the LOAEL for 'slight effects' to a NOAEL (no observed adverse effect level). As the LOAEL was from a population study, a UF to take into account inter-individual variation was said not to be required.
ATSDR (2003)         MRL = 0.005 mg/kg/day                                                                                       Chronic oral MRL derived for selenium based on a NOAEL of 0.015 mg/kg/day for disappearance of symptoms of selenosis in recovering individuals, and an uncertainty factor of 3 to account for sensitive individuals.
US EPA (IRIS 2012)   RfD = 0.005 mg/kg/day                                                                                       RfD (last reviewed in 1991) based on a NOAEL of 0.015 mg/kg/day (same study as considered by ATSDR), and an uncertainty factor of 3.

There is unanimity among the expert groups that the heavily exposed population within mainland China offers the best opportunity of defining the toxicological consequences of long-term oral exposure to 'selenium'—a term which would appear to include all selenium compounds other than the sulphides. The available threshold values for selenium are based on these studies and typically relate to an upper limit (UL); that is, an intake that can be consumed daily over a lifetime without significant risk to human health on the basis of available evidence. The values derived by ATSDR and US EPA are based on a UL from the same studies and they have both considered an uncertainty factor of 3. Review by EA (2009a) suggested that, given the large population group considered in the studies, the use of the uncertainty factor may not be required. There are differences in the interpretation of the various studies used to derived ULs with variability in assumed body weights most significant. Hence there is some variability in the threshold values derived by different organisations.

The value of 0.006 mg/kg/day, the lower UL value recommended/endorsed by NHMRC (2006), is consistent with that derived from CCME (2007) and EA (2009a) and is similar to that derived by ATSDR (2003) and US EPA (IRIS 2012). Hence the UL from NHMRC is considered reasonable for the quantification of oral