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Long-term toxicity to aquatic invertebrates

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Description of key information

The chronic 21 -d EC10 based on reproduction for Daphnia magna was determined to be 4.07 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
4.07 mg/L

Additional information

For dibutylamine (CAS 111 -92 -2) studies on long-term toxicity towards aquatic invertebrates are not available. Therefore, read-across was performed to the structurally similar substance diethylamine (CAS 109 -89 -7).

Under supervision of the Japanese Ministry of the Environment, a chronic test on Daphnia magna was conducted with diethylamine (CAS 109 -89 -7) according to OECD 211 under GLP and published in 2000.The test duration was 21 days, the test solutions were renewed two times per week. The test concentrations were analytically verified and deviated less than 20% from the nominal values. Nevertheless, the results are based on the mean measured test concentrations. The pH values were not adjusted and ranged from 7.6 to 9.9 in the freshly prepared test solutions. Up to 14.7 mg/L, the pH values of the test solutions were within the acceptable range of pH 6 - 9 of OECD 202. After two days of exposure the pH decreased to values between 6.8 and 7.8.The NOEC for reproduction was determined to be 4.2 mg/L (NITE, 2000, report no.: NMMP/E99/3070).

The data of the original report were re-evaluated using ToxRat v3.3 in order to obtain an EC10, which is not originally reported (BASF SE, 2020). According to REACH Guidance document chapter R.10 Table R.10-1 (Overview of toxicity test endpoints and guidance on derivation of L(E)C50 and NOEC values) an EC10 for a long-term test which is obtained using an appropriate statistical method (usually regression analysis) will be used preferentially.

There has been a recommendation within OECD in 1996 to phase out the use of the NOEC, in particular as it can correspond to large and potentially biologically important magnitudes of effect. The advantage of regression method for the estimation of ECx is that information from the whole concentration-effect relationship is taken into account and that confidence intervals can be calculated. These methods result in an ECx, where x is a low effect percentile (e.g. 5-20%). It makes results from different experiments more comparable than NOECs. Based on the recalculation, the study also fulfills the recent validity criteria according to OECD 211.

The 21 -d EC50 (reproduction) was 6.01 mg/L (95% CL: 4.85 - 7.13 mg/L; based on measured concentrations). The 21 -d EC10 (reproduction) was determined to be 4.07 mg/L (95% CL: 2.25 - 4.99 mg/L; based on measured concentrations). These values were selected as key data.