Quality criteria of fish chronic testing

The data for fish toxicity represented a heterogeneous dataset with a variety of species and chronic study types. Therefore, quality criteria were defined and tests were subdivided into FELS studies (n=129) and other chronic study types representing the non-FELS studies (n=40) within the dataset. FELS studies represent the vast majority in the data set and thereby dominate the overall results. The result showed that the type of chronic test affected the average sensitivity distribution. While sensitivity of Daphnia and fish was now comparable if only FELS tests were considered for fish, substance entries underlaid with non-FELS tests

exhibited in average an increased sensitivity to Daphnia in chronic testing (Fig. 14 and Fig.15).

This result suggested that the type of chronic test effected the average sensitivity distribution.

However, the result shown in figure 14 B was almost comparable to the result of the complete dataset in figure 6. The applicability of the categorization system was also confirmed if only FELS tests were considered since the chronic Daphnia test was still indicated for Cat.3 and Cat.4 whereas the fish test was required for Cat.1 to avoid underestimation of fish toxicity by

extrapolation from chronic Daphnia data. Again a chronic fish test was not indicated for Cat.4 and in 7% of the cases for Cat.3. In total, a confidence interval of 95 % was determined for substance with a Qa >0.5 in Cat.3 and Cat.4 since the chronic fish test was indicated for 5 % of the substances. Moreover, the fish test was required in Cat.2 for about 28 % for the substances of the complete dataset compare to about 33 % of the substances for Cat.2 if only FELS test were considered.

For ACR evaluation different quality criteria were defined corresponding to the methodology applied previously (Ahlers et al., 2006). The first (ACR1) included all data across all fish species and test types (Table 5. The second (ACR2) included all test types but was confined to data with acute and chronic results from the same species whereas the third (ACR3) was confined to data from different species. The fourth (ACR4) was restricted to chronic toxicity testing conducted according or equivalent to OECD 210 and the fifth (ACR5) included all chronic studies that were not conducted according or equivalent to OECD 210 representing the non-FELS studies within the dataset. ACR6 only included FELS test on the same species in acute and chronic testing. ACR7 and ACR8 included FELS tests from organic chemicals only.

ACR1, ARC2 and ACR3 showed comparable median values indicating that statistical ACR medians did not differ between evaluations using the same species and evaluations with species differentiation. The 90%-ile value of ACR2 species specific ACRs was reduced compared to ARC1 and ACR3 whereas ACR3 was increased compared to ARC1 and ACR2. Furthermore, a 10%-ile value was 3.4 for the ACR2 whereas a value of 2.7 was determined for inter-species

ile and the 90%-ile value whereas species specific ACRs showed a 19 fold range. This

observation suggested that the variance in data distribution is increased using evaluations of different species.

The study type of chronic testing appeared to have an effect on the ACR, as well. FELS based studies showed a median ACR4 of 13.0 and a 90%-ile value of 81.8 (Table 5). The median ACR5 of 7.2 and the 90%-ile value of 36.6 of non-FELS studies were reduced compared to the FELS based studies. Hence, ACR of FELS studies was in average about 1.8 fold larger than ACR of non-FELS studies. Thus, FELS based studies appeared to be more sensitive to determine chronic toxicity compared to other studies types and may be considered as more conservative.

However, the result on non-FELS studies is based on a limited dataset (n= 23) and interpretation should be handled with care and on a case by case evaluation since different tests types were not compared for the same substance.

ACR6 and ARC8 were considered as data with the highest statistical data quality since only FELS test that were confined to data with acute and chronic results from the same species were included. The median was determined to 12.2 and the 90%-ile was calculated to 63.5 for ACR6.

ACR8 only included FELS tests from organic chemicals. The median was determined to 10.4 and the 90%-ile was calculated to 63.5. 5% of the substance had an ACR >100.

Figure 15: Overview of results of chemicals for fish by different study quality criteria

Sensitivity distribution of Daphnia and fish toxicity was visualized in a pie diagram for substance entries underlaid with data from chronic toxicity testing conducted equivalent to OECD 210 (A) or with data from non-FELS studies (C). Substance entries were allocated to the classification system that is based on quotientacute and described in table 1. The percentage of substances being more toxic to fish in chronic testing and exhibiting a quotientchronic <1 was evaluated for each classification class (black).

Substances that were >5x more sensitive to fish in chronic testing and exhibited a quotientchronic <0.2 was evaluated for each classification class (grey). (B) Data was restricted to chronic toxicity testing conducted equivalent to OECD 210. (D) Data was included from all chronic studies that were not conducted equivalent to OECD 210 and represent the non-FELS studies.

Figure 16: Sensitivity distribution by different test quality criteria of fish studies

Sensitivity distribution between Daphnia and fish was elucidated by a heat map diagram as described in figure 4 for substances underlaid by a FELS or by non-FELS studies.

Table 7: ACR evaluation of chemicals for fish by different study quality criteria

Parameter* ACR1 ACR2 ACR3 ACR4 ACR5 ACR6 ACR7 ACR8

No. of values 123 75 48 100 23 63 89 55

Min. 1.1 1.8 1.3 1.1 1.7 1.9 1.1 1.9

Median 12.2 10.7 12.4 13.0 7.4 12.2 12.1 10.4

90 %-ile 68.0 63.5 111.1 81.8 36.6 63.5 96.6 63.5

Max. 1370.6 1370.6 514.0 1370.6 375.0 1370.6 1370.6 1370.6

ACR1 included data across all fish species and test types. ACR2 included all test types but was confined to data with acute and chronic results from the same species whereas ACR3 was confined to data from different species. ACR4 was restricted to chronic toxicity testing conducted according or equivalent to OECD 210 representing FELS studies. ACR5 included all chronic studies that were not conducted according or equivalent to OECD 210 and represent the non-FELS studies. ACR6 included all tests that were confined to data with acute and chronic results from the same species and where the chronic study was conducted according to

FELS.ACR7 included FELS tests from organic chemicals only. ACR8 included FELS tests from organic chemicals only that were confined to data with acute and chronic results from the same species.