N-[3-(dimethylamino)propyl]oleamide

Toxicity to aquatic algae and cyanobacteria

Description of key information

A toxicity study on aquatic algae with N-[3-(Dimethyl lamino)propyl]oleamide is not available. Consequently, read-across was applied using a characteristically similar compound (CAS# 84082-43-9; Amides, C8-22, N-[3-(dimethylamino)propyl)]. The chronic toxicity of the test item to fresh-water green algae Pseudokirchneriella subcapitata was determined according to the method C.3 of the Directive 92/69/EEC of the European Commission, which is in conformity with the OECD Guideline 201. The results showed an EC50 value of 0.003 mg/L based on cell growth and  0.005 mg/L based on growth rate. The NOEC was 0.002 and 0.003 mg/L based on cell growth and growth rate, respectively. The very low EC50 value may be related to a true algicidal effect of the test item.

Additional information

The chronic toxicity of the test item to fresh-water green algae Pseudokirchneriella subcapitata was determined according to the method C.3 of the Directive 92/69/EEC of the European Commission, which is in conformity with the OECD Guideline 201.
Algae were exposed to a range of concentrations of the test item dissolved in dilution water. The toxic effect measured during the assay was the inhibition of cellular multiplication over a time period of 72 hours. The cell density was measured daily. Analytical chemistry and physico-chemical measurements were carried out at the beginning and the end of the test. The concentration and loading of test item causing a 50% reduction in biomass (EbC50 and EbL50) or in growth rate (ErC50 and ErL50) were determined. The EC50 and NOEC values are derived from the analytical measurements. EL50 -72 hours derived from loading rate of the WAF are also reported.

The results were as follows:

Effective concentrations and loading [mg/L]
	Value	95% Cl
Cell growth (biomass)
EbC50 (72 h)	0.003	ND
NOECb	0.002	-
EbL50 (72 h)	0.022	ND
Growth rate
ErC50 (72 h)	0.005	ND
NOECr	0.003	-
ErL50 (72 h)	0.03	ND

Effective concentrations and NOEC shown in the previous table have been calculated using the geometric average values between initial and final concentrations of the test substance. Concentration were measured by liquid chromatography coupled with mass spectrometry. Initial and final concentrations were not equivalent to nominal concentrations.
The validity criterion of the study related to the growth of algae was fulfilled: the increase in the cell density (R), measured in the control solution between the end and the beginning of the test, was greater than a factor of 16 (R = 66). The validity criterion specific to C3 92/69 EEC method and related to the test item stability during the test was not respected: the final concentrations of the test item were not maintained within the designated limit of 80% of the initial concentrations.
As already discussed for the adsorption / desorption study: The test substance tends to adsorb to the glass container. In general, fatty amines have a very high adsorption to glass surfaces due to its cationic nature. This effect is most noticeable at lower concentrations.