Amides, C16-18, N-[3-(dimethylamino)propyl]

Short-term toxicity to aquatic invertebrates

Description of key information

48 h EC50 = 381 µg/L, nominal (OECD guideline 202, GLP, RL1); read across from Stearic acid 3-(dimethylaminopropyl)amide

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

381 µg/L

Additional information

No experimental data are available for C16-18 DMAPA amidoamine. However, an acute toxicity study in aquatic invertebrates with the read-across substance Stearic acid 3-(dimethylaminopropyl)amide is available. For justification for read-across see endpoint summary "Aquatic toxicity".

 

In the acute immobilisation test with Daphnia magna (STRAUS), the effects of the test item Stearic acid 3-(dimethylaminopropyl)amide were determined according to OECD 202 (2004).

The study was conducted under semi-static conditions over a period of 48 h with 5 concentrations of the test item Stearic acid 3-(dimethylaminopropyl)amide in the range of 62.5 to 1000 µg/L, prepared with natural river water in a geometric series with a separation factor of 2. Twenty daphnids were exposed to each concentration level and the control.

The concentrations of the test item were analytically verified by LC-MS/MS at the start of the exposure intervals (0 and 24 h) and at the end of the exposure intervals (24 and 48 h) in all concentration levels and the control.

The test item has a low water solubility and sorbs to organic and inorganic materials by different mechanisms. The sorption processes are mostly non-linear, means are concentration dependent. Due to these properties the test item is difficult to test in artificial water (e.g. sorption to the test organism and walls of the test vessel). Natural river water contains particulate as well as dissolved organic carbon to which the test item can sorb partially preventing that the test item settles onto surfaces. The sorbed fraction of the test item is difficult to extract from the test system which normally leads to low analytical recoveries. Nevertheless the test item is present in the test system and therefore available for exposure (dissolved in water and sorbed).Due to the properties of the test item the nominal concentrations were used for assessment of the endpoints instead of measured ones.

The water quality parameters (i.e. pH-value and dissolved oxygen concentration), measured at the start (0 and 24 h) and at the end of the exposure intervals (24 and 48 h), were within the acceptable limits. The validity criteria of the test guideline were fulfilled.

The 48 h EC50 was 381 µg/L (95% confidence interval 321 – 427 µg/L) (based on the nominal concentrations).

 

The following study showing similar results with C20/22 ATQ is enclosed to justify the read-across approach for sediment and terrestrial toxicity studies.

In the acute immobilization test to Daphnia magna (STRAUS) with natural river water the effects of the test item C20/22 ATQ were determined according to OECD 202 (2004) and Directive 92/69/EC Method C.2 (1992).

The study was conducted under static conditions with 6 nominal test item concentrations ranging from 0.250 to 3.90 mg/L set up in a geometric series with a dilution factor of √3 over a period of 48 hours. 20 test organisms were exposed to each test concentration and control. All concentration levels and the control were analysed via LC-MS/MS after 0 h (fresh media) and after 48 h (old media).

The test item has a low water solubility and sorbs to organic and inorganic materials by different mechanisms. The sorption processes are mostly non-linear, means are concentration dependent. Due to these properties the test item is difficult to test in synthetic water (e.g. sorption to the test organisms and glass walls of the test vessels) and results from such tests depend from the test settings applied. Using natural river water which contains particulate as well as dissolved organic carbon to which the test item can sorb partially reduces the difficulties encountered in tests with synthetic water (e.g. preventing that the test item settles onto surfaces). The sorbed fraction of the test item is difficult to extract from the test system which normally leads to low analytical recoveries. Due to the short exposure period these low recoveries at the end of the exposure phase (48 hours) cannot be associated to biodegradation. The measured extractable test item concentration in the aqueous phase the test item sorbed to DOC and suspended matter is regarded to be available for the daphnids. Therefore, the exposure concentrations at the end of the exposure phase of 48 h were calculated by correcting the initially measured concentrations versus the test item concentrations sorbed to the glassware.

For the assessment of the endpoints the nominal concentrations of the test item were used, because the calculated exposure concentrations demonstrate that the daphnids were fully exposed to the test item concentrations (dissolved in water and sorbed also called bulk). Due to the properties of the test item nominal concentrations have to be used instead of measured ones. This so called Bulk Approach is described by ECETOC (2003).

The water quality parameters (pH-values and dissolved oxygen concentrations), measured at 0 and 48 h, were determined to be within acceptable limits. The validity criteria of the test guideline were fulfilled. The 48 h EC50 was 1.39 mg/L (95% c.i. 1.29 – 1.49 mg/L).