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Long-term toxicity to aquatic invertebrates

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Benzenepropanoic acid 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-2 -ethyl-hexylester (CAS 144429-84-5): EL50(21d): 100 mg/L, NOELR: 3.2 mg/L, LOELR: 10 mg/L (Goodband and Mullee, 2010)
Butyl 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoate (CAS 52449-44-2): NOEC: 10 mg/L, LOEC: 32 mg/L (Wetton, P.M., Mullee, D.M., 2000) / Test termination after day 8 due to 100 % mortality at all the test loading rate WAFs (Goodband and Mullee, 2010)

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Additional information

Regarding long-term toxicity to aquatic invertebrates of Benzenepropanoic acid, 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-,C7 -9 branched alkyl esters (CAS 125643 -61 -0) neither experimental nor predicted results are available.

The substance Benzenepropanoic acid 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-2 -ethyl-hexylester (CAS 144429 -84 -5) can be considered as a read-across possibility. The substance was tested according to OECD guideline 211 (1998) “Daphnia magna, Reproduction Test” Method C.20 of Commission Regulation (EC) No 440/2008 (Goodband and Mullee, 2010). Based on the results of a preliminary range finding test, Daphnia magna were exposed (10 daphnids per group) to a Water Accommodated Fraction (WAF) of the test item over a range of nominal loading rates of 1.0, 3.2, 10, 32, and 100 mg/L for a period of 21 days. WAFs were renewed 3 times per week. The numbers of live and dead adult Daphnia were fed daily with an algal suspension.

The 21-day EL50 immobilisation value based on nominal loading rates for the parental Daphnia generation was estimated to be greater than 100 mg/L loading rate WAF. The 21-day EL50 reproduction value based on nominal loading rates was estimated to be greater than 100 mg/L loading rate WAF. The Lowest Observed Effect Loading rate was considered to be 10 mg/L. The No Observed Effect Loading rate was considered to be 3.2 mg/L based on immobilization and reproduction. Given that toxicity cannot be attributed to a single component or a mixture of components but to the test item as a whole, the results were based on nominal loading rates only.

The substance Butyl 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoate (CAS 52449 -44 -2) can be considered as another read-across possibility. Two experimental results are available (two key studies, both reliability 1), conducted according to OECD Guidelines for Testing of Chemicals No 211 (1998) "Daphnia magna, Reproduction Test"; Method C.20 of Commission Regulation (EC) No 440/2008. Water Accomondated Fractions (WAFs) were prepared due to the fact that the test item is known as poorly water soluble substance.

In the first available study, Daphnia magna were exposed (10 daphnids per group) to filtered Water Accommodated Fractions (WAFs) of the test material over a range of loading rates of 1.0, 3.2, 10, 32 and 100 mg/L for a period of 21 days (Wetton and Mullee, 2000). The test solutions were renewed 3 times per week. The numbers of live and dead adult Daphnia and young daphnids (live and dead) were determined daily. The animals were daily fed with an algal suspension. Analysis of the freshly prepared test solutions on day 0 showed the measured concentrations to be in the range of less than the limit of quantitation of the analytical method to 0.270 mg/L. On all sampling occasions an increase in measured concentrations was shown with increasing loading rates. A decline was shown in the measured concentration of the old test media. This decline was considered to be due to possible instability of the soluble components of the test material, which was indicated by the pre-study stability work performed. During the pre-study stability analyses, the dissolved components in the filtered WAFs were shown to be a combination of test material and degradation products. Therefore given that toxicity cannot be attributed to the test material alone or to its degradation products, the results are based on nominal loading rates only. The 14 and 21-Day EL(Effective Loading rate)50 (immobilisation) values, based on nominal test loading rates, for the parental Daphnia generation (P1) were calculated to be 18 mg/L loading rates filtered WAF with 95 % confidence limits of 10 - 32 mg/L loading rate filtered WAF. The 21-Day EL50 (reproduction) value based on nominal loading rates was calculated to be 20 mg/L loading rate filtered WAF with 95 % confidence limits of 16 - 25 mg/L loading rate filtered WAF. The "Lowest Observed Effect Loading rate" is considered to be 32 mg/L loading rate filtered WAF on the basis that there were significant mortalities (immobilisation) observed in the parental generation (P1). The "No Observed Effect Loading rate" is considered to be 10 mg/L loading rate filtered on the basis that at this loading rate there were no significant mortalities (immobilisation) observed in the parental generation (P1) and that there were no significant differences (P >= 0.05) between the control and the 10 mg/L loading rate filtered WAF test group in terms of numbers of live young produced per adult by Day 21.

Another study was terminated on Day 8 due to 100% mortality at all the test loading rate WAFs employed prior to the production of young daphnids

(Goodband and Mullee, 2010). Based on the results of a preliminary range-finding test, Daphnia magna were exposed (10 daphnids per group) to a WAF of the test item over a range of nominal loading rates of 1.0, 3.2, 10, 32 and 100 mg/l for a period of 8 days. WAFs were renewed 3 times, whereby adult Daphnia were transferred to fresh media by wide-bore pipette before the contents of each vessel were passed through a fine mesh. The numbers of live and dead adult Daphnia and young daphnids (live and dead) were determined daily. The Daphnia were fed daily with an algal suspension. Potassium dichromate was used as positive control and these groups were maintained under identical conditions but not exposed to the test item. The 7-Day EL50 (Effective Loading rate; immobilisation) value, based on nominal loading rates, for the parental Daphnia generation (P1) was estimated to be less than 1.0 mg/L loading rate WAF. The 21-Day EL50 (reproduction) value could only be estimated as less than 1.0 mg/L loading rate WAF. The Lowest Observed Effect Loading rate (LOEL) could only be estimated as less than 1.0 mg/L loading rate WAF as all loading rates employed in the test showed 100 % mortality in the parental generation (P1) after 7 days exposure. The No Observed Effect Loading rate (NOEL) could only be estimated as less than 1.0 mg/L loading rate WAF given that effects were observed at all loading rate WAF test groups employed in the test.

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