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

Long-term toxicity to aquatic invertebrates

Description of key information

21 d NOEC = 200 µg/L, 21 d LOEC = 400 µg/L, 21 d EC10 = 200 µg/L (95% c.i. 100 – 400 µg/L), nominal (OECD guideline 211, GLP, RL1); read across from Stearic acid 3-(dimethylaminopropyl)amide

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

200 µg/L

Additional information

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

The Daphnia magna Reproduction Test (semi-static, 21 d) of the test item Stearic acid 3-(dimethylaminopropyl)amide was conducted according to OECD 211 (2008). Test species was Daphnia magna STRAUS (Clone 5). Ten daphnids, individually held, were used per concentration level, and control. At test start the daphnids were 2 to 24 hours old. The study was carried out under semi-static conditions with a daily renewal of the test solutions.Nominal concentrations of the test item were selected as follows: 25.0–50.0–100–200–400 µg/L. Stearic acid 3-(dimethylaminopropyl)amide is a tertiary straight chain amine. The test item has a low water solubility of 10 mg/L 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 nominal concentrations have to be used instead of measured ones. The concentrations of the test item were analytically verified by LC-MS/MS of samples taken at the start of the exposure intervals on days 0, 2, 8, 15 (0 h) and at the end of the exposure intervals on days 1, 3, 9, 16 (24 h) of all concentration levels and the control.

The adult mortality was the only significant effect in this study. Effects concerning the reproduction were not observed during the test period of 21 days.

Based on the significant adult mortality of 100 % at the concentration level of 400 µg/L, the No Observed Effect Concentration (NOEC) after 21 days was assessed at 200 µg/L and the Lowest Observed Effect Concentration (LOEC) was assessed at 400 µg/L.

The EC10 for the adult mortality was calculated by sigmoidal dose-response regression to be 200 µg/L (95% confidence limits: 100 – 400 µg/L). The EC50 was calculated accordingly to be 212 µg/L (95 % confidence limits: 100 – 400 µg/L). Effect levels are given as nominal concentration.

 

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

The Daphnia magna Reproduction Test (Semi-Static, 21 d) of the test item C20/22 ATQ was conducted according to OECD 211 (2008). Test system was Daphnia magna STRAUS (Clone 5). 10 test organisms, individually held, were used per concentration level and control. At test start they were 2 to 24 h old. The study was carried out under semi-static conditions with a three times per week renewal of the test solutions.

Nominal concentrations of the test item were selected as follows: 0.0512 - 0.128 - 0.320 - 0.800 - 2.00 mg/L.

The tested concentration levels of the test item and the control were analytically verified via LC-MS of samples on days 0, 9, 14, 16 (fresh media, 0 h) and on days 2, 16 (old media, 48 h), 12 and 19 (old media, 72 h).

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 organism and walls of the test vessel) 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 cannot be associated to biodegradation. This means the test substance is present in the test system and therefore available for exposure (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). Sorption of the test item to the glass ware of the test system was monitored and found to be small.

The Lowest Observed Effect Concentration (LOECreproduction) and the No Observed Effect Concentration (NOECreproduction) after 21 days based on the reduction of the reproductive output as the most sensitive effects in this study were determined directly from the observed reduction of the reproductive output. The EC50-values for the reduction of the reproductive output were estimated directly from the observation data to be > 0.320 mg/L, because effects > 50 % did not occur within the tested concentration range. An EC10- value for the reduction of the reproductive output could not estimated, because the effects were not concentration related. The EC50 for adult mortality after 21 days was calculated respectively to be 0.295 mg/L (Cl: 0.128- 0.800 mg/L). All effect values given are based on the nominal concentrations of the test item.