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The aquatic hazard assessment of N,N-dimethyldecanamide (CAS 14433-76-2) was performed using test results with the substance itself and available data for the source substance N,N-Dimethyldecan-1-amide, mixture with N,N-Dimethyloctan-1-amide (CAS No. 67359-57-3, now handled under EC 909-125-3), as well as with N,N-Dimethyldodecan-1-amide (3007-53-2) which were used in a read across approach in accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5. The existing experimental data demonstrate, that the ecotoxiicity of N,N-Dimethylalkylamides correlates to the hydrophobicity of the molecules. The read across is considered valid as both substances are identical regarding structure and functional groups only slightly differing in the length of the alkyl chain showing C10 in the test substance and C8 and C10 in the read across substance. Valid data are available for the algae toxicity of the source substances C8-10-FADMA (source 1) and C12-FADMA (source 2) from the N,N-Dimethylalkylamides group. The existing experimental data demonstrate, that the ecotoxicity of N,N-Dimethylalkylamides correlates to the hydrophobicity of the molecules. The acute ecotoxicity towards fish, daphnia and algae was deduced using the geometic mean of the LC/EC50 of N,N-Dimethyldecan-1-amide, mixture with N,N-Dimethyloctan-1-amide (CAS No. 67359-57-3) (source substance (1)) and N,N-Dimethyldodecan-1-amide (3007-53-2) (source substance (2)). The resulting LC50 for fish is 3.6 mg/l and the corresponding ErC50 for algae = 3.6 mg/l as well. Daphnia turned out to be the most sensitive species, having an EC50 = 1.55 mg/l.


Using the geometric mean rather than the Loewe formula is justified, because the target substance ist not a mixture between source substance (1) and source substance (2), i.e. it does not contain the more toxic source substance (1).


 


 


Reliable long-term toxicity tests are available for two trophic levels, i.e. fish and invertebrates (2x). The long-term toxicity test to fish was performed according to GLP and OECD guideline 210 using Danio rerio as test organism (BASF, 2013). None of the endpoints assessed showed significant effects and thus the 35-d NOEC value is determined to be > = the highest measured test concentration of 0.71 mg/L. Two studies are available investigating the long-term toxicity to aquatic invertebrates. Both studies are regarded as equally valid. For regulatory purpose, the study exhibiting the lower NOEC/ECx-values was used (worst case approach).  Thus, the key EC10-value was calculated by the geometric mean of the two experimental data points (0.079 mg/l and 0.37 mg/l) and the QSAR prediction of 0.76 mg/l. The chronic value = 0.28 mg/l was used for C&L, as well as for risk assessment (PNEC-derivation). Daphnia turned out to be the most sensitive species. Supporting evidence for the value of 0.28 mg/l as the most presentative regulatory chronic value is obtained by the alternative read across approach using C8-10-FADMA as source substance (1) and C12 FADMA as source substance (2). Calculating the geometric mean of C8-10-FADMA and C12-FADMA experimental results indicates a NOEC = 0.22 mg/l for the target substance C10 FADMA (14433-76-2).   


 


While chronic studies for fish- and daphnia are available for the registered substance itself, algal toxicity was assessed applying the read-across approach using the source substance (1) (N,N-Dimethyldecan-1-amide, mixture with N,N-Dimethyloctan-1-amide, CAS No. 67359-57-3, now handled under EC 909-125-3) and source substance (2) (N,N-Dimethyldodecan-1-amide, 3007-53-2). OECD 201-results are available for a 50:50 mixture of FADMA C8 and FADMA C10, demonstrating a NOEC = 4.2 mg/l as well as for FADMA C12 showing to be more toxic, exhibiting a NOEC = 0.435 mg/l. Based on an interpolation between the shorter and the longer chain-length, i.e. by geometric mean of C8-10-FADMA and C12-FADMA data a NOEC = 1.35mg/l has been deduced for FADMA C10 by read-across approach. This value is used for classification.


 


Since no studies investigating the toxicity of N,N-dimethyldecanamide (CAS 14433-76-2) to aquatic microorganisms is available, data for the source substance N,N-Dimethyldecan-1-amide, mixture with N,N-Dimethyloctan-1-amide (CAS No. 67359-57-3) was used. Based on the respiration rate, the EC50 to activated sludge was determined to be 212.3 mg/L.