Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:11:p6
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 11 (pt 6/9)
Character Range: 2280262–2283347

resulted in a conservative approach that genotoxicity is critical in the development of tumours and that a non-threshold may be appropriate.
    * Non-threshold assessments of inhalation cancer risk have relied on occupational studies to derive a quantitative value (unit risk). These occupational studies relate to specific nickel compounds in the occupational environment including nickel subsulfide (WHO 2000) and nickel refinery dusts (US EPA IRIS 2012).
    * WHO (1991) notes that very high concentrations of nickel are required to produce teratogenic and genotoxic effects.
    * Review by RIVM (2001) suggested the mechanism of action suggests a cytotoxic effect and that a threshold was appropriate for inhalation exposure to nickel. Review by EPAQS (2008, as referenced by EA 2009b) also suggested a non-genotoxic threshold mechanism of action and that a threshold can be considered.
    * A threshold value can be adopted for inhalation exposure that is protective of both carcinogenic and non-carcinogenic effects. However it is noted that the assessment of carcinogenic issues relies on the non-threshold values available and acceptance of a 1 in 100,000 excess lifetime cancer risk.
With respect to the derivation of a soil HIL, nickel is not volatile and hence inhalation exposures are only relevant to dust intakes. Carcinogenic  end points are expected to be of particular importance if they are derived from nickel refinery dust of nickel subsulfide, but dust generated from soil contamination is not likely to be significant and hence the consideration of carcinogenic effects using a non-threshold approach may not be appropriate. It is therefore appropriate to consider intakes on the basis of a threshold approach associated with the most significant end point which includes both carcinogenic and non-carcinogenic effects. These issues were considered by EA (2009b), where a threshold value was recommended that was considered protective of both carcinogenic and non-carcinogenic effects.

The following quantitative threshold values (including guideline values derived to be protective of carcinogenic effects) are available for the assessment of inhalation exposures from Level 1 Australian and International sources:
Source                              Value                        Basis/Comments
Australian – No guidelines derived
International
WHO (2000)                          GV = 0.025 µg/m3             Review by WHO (2000) established a range of air guideline values for nickel based on a non-threshold approach with a unit risk derived from occupation studies associated with nickel subsulfate. It has been assumed that the nickel ion is the active agent in the occupational studies and therefore the studies are relevant to all nickel exposures. The guideline value noted here is based on an excess lifetime cancer risk of 1 in 100,000.
TERA (1999)                         RfC = 0.2 µg/m3              RfC derived on the basis of a benchmark approach using a BMCL10 (HEC) of 0.0017 mg/m3 associated with lung fibrosis from soluble nickel salts in a