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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), which was used in a read across approach in accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5. 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. This structural similarity assumes very similar physico-chemical properties resulting in identical environmental behavior and ecotoxicity.

Since no studies investigating the short-term toxicity of N,N-dimethyldecanamide (CAS 14433-76-2) to freshwater fish, aquatic invertebrates and algae are available, data for the source substance N,N-Dimethyldecan-1-amide,mixture with N,N-Dimethyloctan-1-amide (CAS No. 67359-57-3) were used. All three fish studies exposed fish for 96 h in a static system. Respective LC50 values ranged from 14.8 to 21.1 mg/L. As all studies were of sufficient reliability, the study with lowest LC50 (Clariant 1993), i.e. 14.8 mg/L, was assigned as the key study. The available short-term toxicity study with aquatic invertebrates exposed Daphnia magna for 48h in a static system. The EC50 value is determined to be 7.7 mg/L.

In the available algae study, the 72-h EC50 value for growth rate is determined to be 16.06 mg/L. Based on the acute data, aquatic invertebrates are considered to be the most sensitive species.

 

Reliable long-term toxicity tests are available for all three trophic levels fish, daphnia (2x) and algae. While fish- and daphnia reproduction tests are available for the registered substance itself, algal toxicity data for the source substance N,N-Dimethyldecan-1-amide,mixture with N,N-Dimethyloctan-1-amide(CAS No. 67359-57-3) were used.

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. However, both studies are regarded as equally valid but on its own not adequately reflecting the long-term toxicity of the substance. Therefore, the results of both studies as well as results of QSAR calculations are combined in a weight-of-evidence approach. Thus, the key NOEC value was calculated as the geometric mean of all three available NOEC values, resulting in a NOEC of 0.28 mg/L.

One algal toxicity test performed with the source substance N,N-Dimethyldecan-1-amide, mixture with N,N-Dimethyloctan-1-amide (CAS No. 67359-57-3) was used. In the algae study the growth rate ErC50 (72h) of the test substance is determined to be 16.06 mg/l, while the ErC10 is determined to be 4.17 mg/L.

 

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.