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Toxicity to aquatic algae and cyanobacteria

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Description of key information

Acutely harmful to aquatic algae and cyanobacteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
62.3 mg/L
EC50 for marine water algae:
34 mg/L
EC10 or NOEC for freshwater algae:
21.4 mg/L

Additional information

The toxicity of 2-diethylaminoethanol to aquatic green algae and cyanobacteria was investigated in a study according to the german industrial standard test guideline DIN 38412, part 9 (Oekolimna, 1988). The original data were recalculated with ToxRat v2.10. Based on growth rate, the model recalculated the 72-h ErC50 to be 62.3 mg/L; the 72-h ErC10 was 21.4 mg/L. 

 

The nominal concentrations were 0 (control), 2, 5, 10, 20, 40, 80, 160 and 320 mg/L; they were not analytically verified, but are assumed to be stable due to the the low n-octanol/water partition coefficient (log Kow = 0.21), the high water solubility (WS = 1.0E+06 mg/L at 23 °C), the moderate vapour pressure (VP = 2 hPa, at 22.4 °C) and the low Henry´s law constant (HLC, uncharged: 3.17E-04 Pa*m³/mol) of the chemical. In addition, a test on short-term toxicity to fish conducted according to APHA (1980) standard methods for the examination of water and waste water which are similar to OECD 203 testing guideline (Geiger et al., 1986), as well as a further test on short-term toxicity to aquatic invertebrates according to OECD 202 (Atofina, 1993) showed an acceptable recovery of the test item in the test solutions.

 

Note:

The classification by long-term toxicity results is based on the 72-h ErC10 of 21.4 mg/L determined in the key study for algae (recalculated with ToxRat v2.10). According to the Guidance on information requirements and chemical safety assessment Chapter R.10: Characterisation of dose [concentration]-response for environment ", 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 experimental results are supported by calculations resulting in the same effective concentration range, estimated with ECOSAR v1.11 implemented in EPISuite v4.11. The model calculated for 2-diethylaminoethanol a class-specific 96-h EC50 of 40.7 mg/L (Chronic value: 11.6 mg/L; ECOSAR class: Aliphatic Amines). The neutral organic SAR (baseline toxicity) was calculated to be 706.1 mg/L (96-h EC50) and 128 mg/L (chronic value). The substance is within the model's applicability domain.

 

Based on the available data, the substance is concluded to be acutely harmful to aquatic algae and cyanobacteria.