C16-18-(even numbered)-alkyl fatty acid, compound with C16-18-(even numbered)-alkylamine

Toxicity to aquatic algae and cyanobacteria

Description of key information

The keys values for this endpoint were obtained with coco alkyl amine and correspond to a 72h-ErC50 of 0.16 mg/L and a NOECr of 0.06 mg/L.
These data have been used as read-across for the registered substance. They are then converted to the corresponding value of the salt, resulting to an ErC50 of about 0.44 mg/L and a NOECr of about 0.165 mg/L (MW of Amines, coco alkyl = 194-204 g/mol, MW of the registered substance = 547.5 g/mol (263 g/mol hydrogenated tallow alkyl amine + 284.5 g/mol acid stearic)).

Key value for chemical safety assessment

EC50 for freshwater algae:

0.44 mg/L

EC10 or NOEC for freshwater algae:

0.165 mg/L

Additional information

Data available for primary alkyl amines:

The lowest effect values (nominal) for aquatic algae have been found for coco alkyl amine (96h-EbC50 = 0.0008 mg/l, 96-NOEC = 0.0002 mg/l), hydrogenated tallow alkyl amine (96h-EbC50 = 0.012 mg/l, 96-NOEC = 0.008 mg/l) and tallow alkyl amine (96h-EbC50 = 0.007 mg/l, 96-NOEC = 0.002 mg/l). These studies were conducted according to the OECD Guideline 201 (1984) with Scenedesmus subspicatus as test organism by Handley (1991c-e):

For the preparation of the stock solutions solubilizer were used. The test vessels were exposed to the test substance overnight to allow pre-adsorption onto the surface of the glassware. At the start of the tests the glassware was rinsed with the test solution to be tested and then refilled with the fresh test solution. Samples for measurement of growth were taken every 24 hours and the absorbance was determined with a photometer at 665 nm. The cell densities of the control cultures at initiation and at termination were measured by direct counting. As no analytical measurements were performed, test results were based on nominal concentrations.

The actual cell concentration in the control after 72 hours is not given in the test reports but an estimation can be made by plotting the absorbance against cell number of the 0 and 96 h control values and assuming that the calibration was linear up to the maximum absorbance used. This estimation leads to conclusion that in the studies with coco alkyl amine and hydrogenated tallow alkyl amine the increase of cell concentration in the control was to low (well below factor 16). For this reason and due to the missing analytical data at very low effect concentration levels, the test results of Handley (1991c-e) are regarded as not suitable for effects assessment purposes.

Other EC50-values reported for primary fatty amines are in the nominal concentration range between 0.04 mg/l (oleylamine, tested in synthetic medium) and0.46mg/l (oleylamine, tested in natural river water).

For coco alkyl amine, tallow alkyl amine and oleylamine, test results are available, which were determined in natural, unfiltered river water (Noack 2002 d-f). Studies were conducted according to the OECD Guideline 201 (1984) in a static test system (temperature approx. 23°C, pH approx. 8) with Desmodesmus subspicatus (Scenedesmus subspicatus) as test organism. A pre-treatment of test vessels was not performed. Again, water of the river “Böhme” was used as dilution water (see section 7.1.1.2.2-1, long term toxicity). Exposure concentrations were analytically verified at 0 and 72 h in the highest tested concentration using GC/MS-analysis. Again, due to variations in the content of suspended matter and the adsorbing properties of the test substances, decreasing test concentrations associated with strongly varying recovery rates were observed(coco alkyl amine: 0-120%, mean 60%; tallow alkyl amine: 73-23%, mean 48%; oleylamine: 72-0%, mean 36%). Test results were therefore based on nominal concentrations. Referring to nominal concentrations for coco alkyl amine a 72h-ErC50 of 0.16 mg/l (72h-NOEC of 0.06 mg/l), for tallow alkyl amine a 72h-ErC50 of 0.39mg/l (72h-NOEC of 0.125 mg/l) and for oleylamine a 72h-ErC50 of 0.46 mg/l (72h-NOEC of 0.15 mg/l) was determined indicating a slight decrease of toxicity with raising chain length.