Diethylamine

Toxicity to aquatic algae and cyanobacteria

Description of key information

Diethylamine is acutely harmful to algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

50.9 mg/L

EC10 or NOEC for freshwater algae:

34.3 mg/L

Additional information

To assess the acute and chronic toxicity of diethylamine (CAS 109 -89 -7) to aquatic algae, under supervision of the Japanese Ministry of the Environment a test on the green algae Pseudokirchneriella subcapitata according to OECD 201 and under GLP was conducted and published in 2000. The test concentrations were analytically verified and the concentrations of diethylamine in freshly prepared test solutions deviated less than 20% from the nominal concentrations. In the aged test solutions, the measured test concentrations were around 50% from the nominal concentrations. The results in the original study report are based on the nominal concentrations. The 24 -h - 72 -h NOEC was 50 mg/L, the 24 -h-72 -h ErC50 was 75.3 mg/L (nominal, 95% CL: 69.5 - 82.5 mg/L; NITE 2000, report no.: EMMP/E99/1070). On the NITE homepage - JCHECK, the results differ from those in the original study report. They are probably based on measured concentrations. The 72-h NOEC was 11 mg/L and the 72 -h EC50 based on growth rate was determined to be 54 mg/L (NITE, JCHECK, accessed January 2020) .

The data of the original report were re-evaluated using ToxRat v3.3 in order to obtain an EC10, which is not originally reported (BASF SE, 2020). According to REACH Guidance document chapter R.10 Table R.10-1 (Overview of toxicity test endpoints and guidance on derivation of L(E)C50 and NOEC values) an EC10 for a long-term test which is obtained using an appropriate statistical method (usually regression analysis) will be used preferentially.

There has been a recommendation within OECD in 1996 to phase out the use of the NOEC, in particular as it can correspond to large and potentially biologically important magnitudes of effect. The advantage of regression method for the estimation of ECx is that information from the whole concentration-effect relationship is taken into account and that confidence intervals can be calculated. These methods result in an ECx, where x is a low effect percentile (e.g. 5-20%). It makes results from different experiments more comparable than NOECs. The recalculation fulfills the required validity criteria.

For the re-evaluation, geomean concentrations were calculated. The 72 -h ErC50 was 50.9 mg/L (95% CL: 49.3 - 52.4 mg/L; based on geomean concentrations). The 72 -h ErC10 was determined to be 34.3 mg/L (95% CL: 32.0 - 36.3 mg/L; based on geomean concentrations). These values were selected as key data.

For the green algae Chlorella pyrenoidosa van Leeuwen et al., 1985 determined an 96h-EC50 of 56 mg/L (nominal) based on the growth rate.