Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:6:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 6 (pt 3/5)
Character Range: 2174399–2177171

was noted that, based on data presented by IARC (1991), cobalt can be detected in plants. Whether cobalt is essential to plant growth has not been well established, however it appears that plant uptake may be somewhat significant and, as such, has been included in the derivation of HIL A. Review by WHO (2006) notes that, although plants may take up cobalt from the soil, the translocation of cobalt from the roots to other parts of the plant is not significant.

Based on the above, the uptake of cobalt into all crops has been considered in the derivation of the HIL A. Limited plant uptake data is available, and translocation into above ground crops is assumed to be negligible, hence the value presented by RAIS (2010) of 0.023 mg/kg fresh produce per mg/kg soil has been considered for root and tuber crops only.

It is noted that the inclusion of home-grown produce in the calculations presented for HIL A results in some double counting of intakes from fruit and vegetable produce (also included in background intakes). To address this in the derivation of HIL A, half the intake estimated to be derived from home-grown produce is assumed to be already accounted for in the total background intake (noted below).

    6.3.5         Intakes from Other Sources – Background
The most significant source of intake of cobalt from sources other than contamination is dietary intake (WHO 2006). Cobalt intakes were considered in the 23rd Australian Total Diet Study (FSANZ 2011), where intakes for a child aged 23 years ranged from a mean of 1 µg/kg/day to a 90th percentile of 1.3 µg/kg/day. RIVM (2001) reviewed background intakes of cobalt, which were considered to be 0.3 µg/kg/day, consistent with intakes from food noted by WHO (2006, where a body weight of 70 kg was assumed). These intakes are between 20% and 70% of the recommended oral TRV. Given the lack of data in support of oral TRVs for cobalt, the only available value from RIVM has been adopted, the lower value of 20% in the derivation of soil HILs.

Cobalt was reported in ambient air data collected in NSW (DEC 2003) where concentrations in urban, regional and industrial areas assessed ranged from 0.10.39 ng/m3. Intakes associated with these concentrations are negligible compared with intakes from food and the recommended inhalation TRV.

6.4              Identification of Toxicity Reference Values

    6.4.1         Classification
The International Agency for Research on Cancer (IARC 1991) has classified cobalt metal, cobalt sulphate and other soluble cobalt (II) salts as Group 2B—possible human carcinogen. IARC provided further review in 2006 classifying cobalt sulphate and other soluble cobalt (II) salts as Group 2B, cobalt metal without tungsten carbide as Group 2B and cobalt metal