Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:11:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 11 (pt 1/9)
Character Range: 2267064–2270035

11             Nickel

11.1          General
Several comprehensive reviews of nickel in the environment and its toxicity to humans are available and should be consulted for more detailed information not presented in this summary (ATSDR 1997; ATSDR 2005; WHO 1991; EA 2009a). The following provides a summary of the key aspects of nickel that are relevant to the derivation of a soil HIL.

Nickel is a silvery white metal that is stable under environmental conditions. It occurs naturally in the Earth's crust. It is the 24th most abundant element and is primarily found as oxides or sulfides (ASTDR 1997). Nickel is extracted from mined ore via pyro- and hydrometallurgical refining processes. Most nickel is used for the production of stainless steel and other nickel alloys with high corrosion and temperature resistance. The primary sources of nickel emissions into the atmosphere are the combustion of coal and oil for heat or power generation, the incineration of waste and sewage sludge, nickel mining and primary production, steel manufacture, electroplating and cement manufacturing (WHO 1991).

The chemistry of nickel is complex, and the toxicological properties of the various compounds depend on physicochemical characteristics, surface chemistry, solubility, geological history. Hence it is important that any site specific assessment of nickel consider these issues.

11.2          Previous HIL
The derivation of the previous HIL (HIL A = 600 mg/kg) is presented by Turczynowicz & Sabordo (1996). In summary, the HILs were derived on the basis of the following:
    * Based on available information from Australia, background intakes for a 2 ½-year-old child were estimated to comprise up to 179.88 µg/day.
    * A reference dose (RfD) of 0.02 mg/kg/day, referenced from a study by Hall & Rumack (1995) was adopted as the toxicity reference value.
    * Dermal absorption was considered to be negligible.
    * Based on potential intakes via ingestion, inhalation and intake derived from home-grown produce, a soil criterion in the range of 200 mg/kg (with produce) to 800 mg/kg (no produce) was suggested.
    * A soil criterion was also derived on the basis of hypersensitivity with the target population being those that have been sensitised in the community. Based on an oral provocation threshold of 0.0083 mg/kg/day, referenced from NHMRC/ARMCANZ (1994), and consideration of nickel leachability (83%), a soil HIL of 600 mg/kg was derived.
    * The calculated soil HIL was considered to also be adequately protective of carcinogenic risks associated with inhalation exposures.

11.3          Significance of Exposure Pathways
Ingestion of soil and dust is considered the most significant pathway of exposure for inorganics in soil. The consideration of bioavailability and inclusion of other exposure pathways in the derivation of a soil HIL has been further reviewed, as noted below.

    11.3.1     Oral Bioavailability
Bioavailability has not been