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Ecotoxicological information

Endpoint summary

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Description of key information

Additional information

Based on lowest reliable acute toxicity values for aquatic species the chemical is considered to be toxic for aquatic organisms:

The lowest, reliable acute toxicity values for aquatic species are:

- Oncorhynchus mykiss (fish): 96-h LC50= 460 mg/L (nominal, analytically verified)

- Ceriodaphnia dubia (invertebrates): 48-h EC50= 30 mg/L (nominal)

- Pseudokirchneriella subcapitata (algae): 72-h ErC50= 9.5 mg/L (nominal; recalculated with ToxRat v2.10)

- Toxicity to microorganisms (activated sludge, domestic): 30 min EC10 >1000 mg/L (nominal)

- Pseudomonas sp. (microorganisms): 16-h TTC= 16 mg/L (nominal)

The reliable chronic toxicity values for aquatic species are:

- Daphnia magna (invertebrates): 21 -d EC10 = 1.05 mg/L (nominal, based on analytical verification; recalculated with ToxRat v2.10).

- Pseudokirchneriella subcapitata (algae): 72-h ErC10= 1.1 mg/L (nominal; recalculated with ToxRat v2.10)

A considerable amount of data on aquatic toxicity of DEA is available. All acute toxicity tests performed without analytical verification of the test concentrations with the only exception of the key study for fish and a study with Hyalella azteca (amphipod). However, from the available acute key data and a chronic toxicity study on aquatic invertebrates (Daphnia magna), also conducted with analytical monitoring, it can be deduced that DEA is rather stable in static test systems for at least 48 hours. Moreover, the stability of DEA in the test medium is considered to be stable due to the high water solubility (WS = 1E+06 mg/L), the low vapour pressure (VP = 8.5E-05 hPa at 20°C) and the low Henry´s law constant (HLC (uncharged): 3.97E-06 Pa*m3/mol; pH-corrected HLC (pH 5-9): 4.06E-10 to 2.01E-06 Pa*m3/mol) of the substance.

 

DEA is an ionisable substance with a pKa of ca. 9 (20 °C). At pH 7 - 8 it is supposed to occur predominantly as cation; at higher pH (> 9) the uncharged species will predominantly occur. Therefore, the toxicity of DEA might also depend on the pH of the test solution, leading to higher toxicity at higher pH values. However, results are contradictory. In a screening test with Desmodesmus subspicatus (BASF AG, 1992), the reported toxicity was higher when neutralised test solutions were applied. Since pH values in the algae tests often vary from 8 - 10, these results may reflect different ecotoxicological behaviour of the uncharged/charged DEA, but might also be explained by intra-laboratory and/or biological variability.

 

Remark on the assessment of long-term toxicity to algae and daphnids:

The classification by long-term toxicity results is based on the lowest available ErC10 value determined for algae (72-h ErC10 = 1.1 mg/L) instead on the lowest NOEC available (72 -h NOEC = 0.6 mg/L). 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".