Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:20:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 20 (pt 3/14)
Character Range: 1302006–1304804

in the Australian and New Zealand WQGs (ANZECC & ARMCANZ 2000). For organics, only chronic NOEC data was considered acceptable to derive high reliability TVs, while only acute EC/LC50 values were suitable for moderate reliability TVs and either NOEC or EC/LC50 data was suitable for low reliability TVs (Warne 2001). In contrast, for metals, chronic NOEC, LOEC, EC/LC50 and maximum acceptable toxicant concentrations (MATC) values could be used provided all non-NOEC values were converted to NOEC values (Warne 2001). This was done using a series of default conversion factors (see Table 8 below). The reason for the different approaches was that for the organic contaminants, generally the chronic data was NOEC values, whereas the vast majority of the chronic metal toxicity data was EC/LC50 values (Warne 2001).

Table 8. Default conversion factors used to convert different chronic measures of toxicity to chronic NOECs in the Australian and New Zealand WQGs (ANZECC & ARMCANZ 2000). Values are from Warne (2001).
Toxicity dataa                Conversion factor
EC50 to NOEC or EC10          5
LOEC or EC30 to NOEC or EC10  2.5
MATC* to NOEC or EC10         2

a EC50, EC30 and EC10 values are the concentrations that cause a 50%, 30% or 10% effect, NOEC = the no observed effect concentration, LOEC = lowest observed effect concentration, MATC = the maximum acceptable toxicant concentration and is the geometric mean of the NOEC and LOEC.
The more flexible method that was applied to the metals in the Australian and New Zealand WQGs (ANZECC & ARMCANZ 2000) and the conversion factors that were used (see Table 8) were used in the EIL derivation methodology. It should be noted that these conversion factors are based on expert judgement (Warne pers. comm.). Therefore, if sufficient terrestrial data is available to derive terrestrial conversion factors then these should be used. For example, data from the Australian National Biosolids Research Program indicates that the phytotoxicity chronic EC10 to chronic EC50 conversion factor for cations such as Cu and Zn was 3 (unpublished data).

Compared to aquatic toxicity studies, there is a limited number of terrestrial toxicity studies. Therefore, maximum use must be made of the available toxicity data and data should be converted from one measure to another (see above).

However, if more data become available then it should be used in the following descending order of preference:
    1. 30% effect data (e.g. EC30, LC30)
    2. LOEC data
    3. 10% or 50% effect data (e.g. EC10, LC50)
    4. NOEC and MATC.
There are a number of well-acknowledged limitations to NOEC and LOEC data (Newman 2008; Fox 2008; Warne & Van Dam 2008). Some scientists (Chapman et al. 1996) have argued that they should not be used to derive EQGs. However,