Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p15
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 15/21)
Character Range: 1384238–1387010

1992; Schudoma 1994; Rand et al. 1995; OECD 1995; Warne 1998). Goldberg (1975) asserted that using AFs was tantamount to admitting that information essential for risk assessments was lacking.

Nicholson (1984) considered that:
'There is little scientific basis for application factors except that they are the result of careful judgement  there is little evidence, in most cases, that the arbitrary value chosen is indeed the best choice, i.e. whether a particular value for an application factor will provide 'adequate' protection and whether a less (or more) stringent value would be more appropriate.'

The fact that there is no universally accepted magnitude for AFs (as seen in Table 18) confirms their arbitrary nature. The AF method ignores all other data except the lowest and is therefore an example of the 'worst-case scenario' type of approach. Such a procedure is at odds with a risk-based approach, which requires an array of data in order to derive estimates of the probability of certain toxicological events occurring. Risk-based concepts and procedures are central to many of the more recently adopted scientific, social and political paradigms within Australia including the current Australian and New Zealand Guidelines for fresh and marine water quality (ANZECC & ARMCANZ 2000).

There has been considerable discussion in the scientific literature about the appropriate size of AFs. There are numerous examples of where AFs should be less than 10 and equally numerous examples of where they should be considerably larger (refer to Warne (1998) and Chapman et al. (1998) for detail). Chapman et al. (1998) concluded that the discussion about the size of the AFs is 'to some extent futile … because no one set of factors has universal applicability'. Ultimately, AFs are a measure to address a lack of knowledge and as soon as that knowledge is available, AFs should no longer be used.

3.2.3.2         Strengths and weaknesses
The strengths of AF methods are that:
    * they are simple to use
    * they are easily understood
    * EILs can be derived with as little as one toxicity value
    * the more unreliable the data the larger the AF becomes – thus taking into account the increased uncertainty
    * the magnitude of the AFs can easily be modified to reflect new toxicological findings but this is invariably not done.

The weaknesses of AF methods are that:
    * the AFs have no theoretical basis; they are purely empirical
    * there is debate over the scientific validity of acute-to-chronic ratios
    * the method is at odds with risk assessment principles
    * the method is not transparent, as it does not state the degree of protection provided by an AF of a certain magnitude and thus does not permit informed decisions and debate