There are six classes of reliability: very high, high, moderate, low and very low, with the sixth class of unknown reliability being assigned to GVs derived using the AF method (see Section 1.1). The reliability of GVs associated with various combinations of these three factors is presented in Table 7. It is recognised that there are other factors that are not considered in the assessment of GV reliability that may affect the accuracy of the GV. Two such factors, and appropriate caveats that should accompany the reliability classification if applicable to the chemical being assessed, are: Example 1. Toxicity datasets spanning 4 or more orders of magnitude. An appropriate caveat would be that GVs based on data with such a large range of values tend to be highly conservative and uncertain, especially at the 99% species protection level. Example 2. A heavy reliance on standard, single-generation toxicity studies for persistent, bioaccumulative and toxic (PBT) chemicals. An appropriate caveat would be that GVs for PBT substances that are not based on multi-generation tests are likely to not provide sufficient protection to aquatic ecosystems. In the event that other factors are deemed to significantly affect the accuracy of the GVs, then similarly appropriate caveats should be provided. Table 7 Classification of the reliability of guideline values using the SSD method SAMPLE ADEQUACY OF ADEQUACY OF FIT IN DATA TYPE RELIABILITY SIZEa SAMPLE SIZE SSD Good Very high ≥15 Preferred Poor Moderate Good High 8–14 Chronicb Good Poor Moderate Good Moderate 5–7 Adequate Poor Low Good Moderate ≥15 Preferred Combined chronic and converted acute Poor Low or Good Moderate Combined chronic fresh and chronic marine 8–14 Good Poor Low Good Moderate 5–7 Adequate Poor Low Good Moderate ≥15 Preferred Poor Low Good Moderate 8–14 Converted acute Good Poor Low Good Low 5–7 Adequate Poor Very low a The sample size is assumed to comprise data from at least four taxonomic groups. b This includes all types of data irrespective of whether they are chronic NEC, BEC10, EC10 and NOEC values or estimates of chronic EC10 and NOEC values that were converted from chronic LOEC, MATC or EC50 data.
There are six classes of reliability: very high, high, moderate, low and very low, with the sixth class of unknown reliability being assigned to GVs derived using the AF method (see Section 1.1). The reliability of GVs associated with various combinations of these three factors is presented in Table 7. It is recognised that there are other factors that are not considered in the assessment of GV reliability that may affect the accuracy of the GV. Two such factors, and appropriate caveats that should accompany the reliability classification if applicable to the chemical being assessed, are: Example 1. Toxicity datasets spanning 4 or more orders of magnitude. An appropriate caveat would be that GVs based on data with such a large range of values tend to be highly conservative and uncertain, especially at the 99% species protection level. Example 2. A heavy reliance on standard, single-generation toxicity studies for persistent, bioaccumulative and toxic (PBT) chemicals. An appropriate caveat would be that GVs for PBT substances that are not based on multi-generation tests are likely to not provide sufficient protection to aquatic ecosystems. In the event that other factors are deemed to significantly affect the accuracy of the GVs, then similarly appropriate caveats should be provided. Table 7 Classification of the reliability of guideline values using the SSD method SAMPLE SIZEa DATA TYPE ADEQUACY OF SAMPLE SIZE ADEQUACY OF FIT IN SSD RELIABILITY ≥15 Chronicb Preferred Good Very high Poor Moderate 8–14 Good Good High Poor Moderate 5–7 Adequate Good Moderate Poor Low ≥15 Combined chronic and converted acute or Combined chronic fresh and chronic marine Preferred Good Moderate Poor Low 8–14 Good Good Moderate Poor Low 5–7 Adequate Good Moderate Poor Low ≥15 Converted acute Preferred Good Moderate Poor Low 8–14 Good Good Moderate Poor Low 5–7 Adequate Good Low Poor Very low a The sample size is assumed to comprise data from at least four taxonomic groups. b This includes all types of data irrespective of whether they are chronic NEC, BEC10, EC10 and NOEC values or estimates of chronic EC10 and NOEC values that were converted from chronic LOEC, MATC or EC50 data.
warne-wqg-derivation2018.docx