Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p6
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 6/8)
Character Range: 2137445–2140248

RfD = 0.0005 mg/kg/day for intakes from water and           Cadmium was last reviewed by the US EPA in 1994. The RfD for intakes from water were derived on the same basis as considered by ATSDR. RfD were derived for intakes from food on the basis of a NOAEL of 0.01 mg/kg/day from chronic human studies and an uncertainty factor of 10.
                    RfD = 0.001 mg/kg/day for intakes from food

The available toxicity reference values or oral intakes are similar from the above sources with the PTMI established by JECFA (WHO 2010) providing the most current review of the available studies. This value has therefore been recommended for use as the oral TRV in the derivation of a soil HIL. This is consistent with that adopted in the ADWG (NHMRC 2011).

    4.4.4         Inhalation Exposures
Inhalation of cadmium has been associated with carcinogenic effects (as well as others). Sufficient evidence is available (IARC 2012) to conclude that cadmium can produce lung cancers via inhalation. While cadmium is thought to be potentially genotoxic, the weight of evidence is not clear. In addition, epidemiology studies associated with lung cancer have confounding issues that limit useful interpretation (WHO 2000). It is noted that US EPA derived its inhalation unit risk on the basis of the same study that WHO dismissed due to confounding factors. In particular, a significant amount of the epidemiological data available also includes co-exposures with zinc and, in some cases, both zinc and lead.

With respect to the derivation of a soil HIL, cadmium is not volatile and hence inhalation exposures are only relevant to dust intakes. These are not likely to be significant for soil contamination and hence the consideration of carcinogenic effects (where the mode of action is not clear) using a non-threshold approach is not considered appropriate. It is appropriate to consider intakes on the basis of a threshold approach associated with the most significant end point. This is consistent with the approach noted by RIVM (2001) and considered by WHO (2000) and EA (2009a), where a threshold value for inhalation based on the protection of kidney toxicity (the most significant end point) has been considered. The value derived was then reviewed (based on the US cancer value) and considered to be adequately protective of lung cancer effects. On this basis WHO (2000) derived a guideline value of 0.005 µg/m3 and EA (2009a) derived an inhalation TDI of 0.0014 µg/kg/day (which can be converted to a guideline value of 0.005 µg/m3—the same as the WHO value).

    4.4.5         Recommendation
On the basis of the discussion above, the following toxicity reference values (TRVs) have been adopted for cadmium in the derivation of HILs:

4.5              Calculated HILs
On the basis of the