Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:14:p4
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 14 (pt 4/9)
Character Range: 2341343–2344518

free cyanide in the Australian environment are provided in the review undertaken by NICNAS (2010). In general, cyanides can occur naturally at low concentrations in ground and surface water with the ADWG (NHMRC 2011) noting that naturally occurring free cyanide in the water supply is usually less than 0.01 mg/L. Concentrations of free cyanide are available for areas near industrial emissions (including former manufacturing plants), mining operations and accidents. However, concentrations relevant to background intakes by the general public away from these areas are not readily available. While background exposure relevant to the general public is difficult to quantify based on limited information, it is not considered reasonable that the background intake is assumed to be negligible (0%).

WHO (2011) notes that even healthy individuals have a small amount of cyanide in their bodies (mainly associated with the breakdown of cyanogenic foods, vitamin B12 and heavy smoking).  DEFRA & EA (2002) identified a range of potential intakes from food (4.228 µg/kg/day) and air (0.06 µg/kg/day). Estimates presented by CCME (1997) suggested intakes of free cyanide from air, water and soil may be greater than 0.11 µg/kg/day in infants, lower than estimated by the UK. These intakes vary significantly and have been assumed to comprise approximately 50% of the recommended oral TRV. Background concentrations in air are less than 2% of the recommended inhalation TRV, which are considered to be negligible.

14.4          Identification of Toxicity Reference Values

    14.4.1     Classification
The International Agency for Research on Cancer (IARC) has not classified cyanide and US EPA has classified cyanide as Group D—not classifiable.

    14.4.2     Review of Available Values/Information
The information on free cyanide toxicity should emphasise the high acute toxicity, which also complicates the interpretation of available data and studies relevant to the assessment of chronic effects and establishing quantitative values. While data is limited, the weight of evidence (WHO 2004, US EPA 2010 and ATSDR 2006) suggests that cyanide in not genotoxic and that it induces developmental effects only at doses or concentrations that are toxic to the mothers. Limited/insufficient information is available on carcinogenicity of cyanide.  On this basis, consideration of a threshold doseresponse approach is appropriate. The following threshold values are available from Level 1 Australian and International sources:
Source                                       Value                                          Basis/Comments
Australian
ADWG (NHMRC 2011) and former WHO DWG (2003)  TDI = 0.012 mg/kg/day                          Derived from a NOEL of 1.2 mg/kg/day from a 6-month feeding study in pigs (Jackson et al. 1986 and Jackson 1988) and a 100-fold safety factor. The cyanide species is not stated in the guidance provided. Review of the study by NICNAS (2010) and WHO (2004) suggested it was not appropriate as the test animals were experimentally compromised.
NICNAS (2010)                                No ADI recommended                             No ADI