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Environmental fate & pathways

Endpoint summary

Administrative data

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Additional information

Amides, C18-unsatd., N-[3-(dimethylamine)propyl] are protonated under environmental conditions.

This means that they will sorb strongly to negatively charged substances like glassware, soil and sediment constituents. For three different soils Kd values were observed ranging from: 2500 to 4500 L/kg. Biodegradation is considered to be the main removal mechanism of this substance. The half-life in the different environmental compartments is expected to be short. No data is available for the determination of the half-life of Amides, C18-unsatd., N-[3-(dimethylamine)propyl] in soil or sediment.These values are therefore estimated as a worst-case based on the readily biodegradability of the available fraction and the sorption data as determined in a sorption desorption test.

A biodegradability study has been carried out according to the method described in the appendix C.4-C of EEC Directive 92/69/CEE (Boutonnet, 1994). This protocol is compliant with OECD Guideline nº 301B adopted on 17/7/92. Under the test conditions, the percentage of biodegradation of the substance was 20% at the end of the test (28 days). Under tests conditions, the test substance is assessed not readily biodegradable. However, two other studies have been performed according to the OECD guideline 301 D “Ready biodegradability - Closed Bottle Test” and GLP requirements (Gancet, 2009). Under the test conditions, the percentage of biodegradation of 2 mg/L of test item reached 75 % of the ThOD at the end (28 days) of the first test and 60% in the second one . All the validity criteria were fulfilled. The 10-day window condition was reached in the first test. In the second test, this criterion was not reached but since this surfactant cationic is a fatty amine derivative and an UVCB, this criterion can be waived.

To conclude, Amides, C18-unsatd., N-[3-(dimethylamine)propyl] was assessed to be readily biodegradable.

Since the substance is readily biodegradable under aerobic conditions, no hydrolysis is required. Nevertheless,  biotic or abiotic hydrolysis may occur in the environment as the first step in biodegradation has been identified as an hydrolysis clearly indicated that the chemical structure is susceptible to hydrolysis.

The continuous activated sludge (CAS) test was performed according to ISO Guidelines, and in compliance with the OECD principles of Good Laboratory Practice. Amides, C18-unsatd., N-[3-(dimethylamine)propyl] were exposed to micro-organisms maintained by addition of domestic wastewater in the CAS test. The test substance was spiked at a nominal influent concentration of 50 mg/L (36.5 mg/L carbon; calculated) for a period of 48 days and included a control fed with domestic wastewater only. The immediate high removal percentages can be attributed to adsorption and probably biodegradation.

The mean removal percentage of test substance calculated over 14 measurements obtained from day 35 to 48 of the test was 105 +/-1% (95% confidence interval). These high removal percentages strongly indicate that test substance is biodegraded ultimately. Formation of water-soluble compounds during biological treatment of test substance can be excluded.

An accurate assessment of the removal of Amides, C18-unsatd., N-[3-(dimethylamine)propyl] was established with specific analyses. The method (LC-MS/ MS) for the determination of test substance was satisfactory with regard to the linearity, repeatability of the injections, limit of quantification (LOQ), recovery and specificity. The mean removal percentage of test substance in the test unit was assessed with the specific analysis from day 44 to 48 was >99.997% using octadecenamide-N- [3-(dimethylamino)propyl] as representative component. These analyses demonstrate that the removal of substance is almost complete. Concentrations in the sludge of the reactor sampled on days 47 and 48 were 341 and 24 µg/L. Mean removal percentages from the influent through adsorption onto sludge assessed in two samples was therefore <0.02% demonstrating that Amides, C18-unsatd., N-[3-(dimethylamine)propyl] is primarily removed by biodegradation. In conclusion, the CAS test demonstrates that Amides, C18-unsatd., N-[3-(dimethylamine)propyl] almost completely removed from the wastewater in conventional biological wastewater treatment plants. Amides, C18-unsatd., N-[3-(dimethylamine)propyl] is primarily removed by biodegradation.

Due to the cationic surface-active properties will Amides, C18-unsatd., N-[3-(dimethylamine)propyl] adsorb strongly onto the solid phase of soil and sediments. The substance can adsorb both onto the organic fraction and, dependent on the chemical composition, onto the surface of the mineral phase, where sodium and potassium ions can be exchanged against the alkyl ammonium ion. The determination of a Koc from log Kow is not opportune, because the common equations for Koc derivation are not valid for both ionic and surface active substances. Therefore not the Koc values should be evaluated but the Kd values. Therefore the Kd values are reported and not the Koc values. Kd values range from 2500 to 4500 L/kg with an average of 3300 L/kg.

To address the bioaccumulation potential according to REACH requirements, the log Kow of Amides, C18-unsatd., N-[3-(dimethylamine)propyl] was measured applying slow stirring method according to OECD 123. The observed log Kow value (Log Kow>3) indicates that the substance may have a bioaccumulation potential if the substance would have been a narcotic substance. For polar narcotics like the Amides, C18-unsatd., N-[3-(dimethylamine)propyl] however there is only limited information on the relationship between log Kow and BCF. Performance of a standard aquatic exposure based OECD 305 test is however not considered. Amides, C18-unsatd., N-[3-(dimethylamine)propyl] sorbs easily to negatively charged surfaces like glassware, clay etc... Standard OECD 305 tests are therefore technically not feasible with these strongly sorbing easily degradable substances. In addition is the route of exposure unrealistic for these substances because the substance will either be sorbed or biodegraded.