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Short-term toxicity to fish

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Description of key information

With high probability acutely not harmful to fish.

Key value for chemical safety assessment

Additional information

An experimental study on the acute toxicity of 2-[2-(dimethylamino)ethoxy]ethanol (DMEE, CAS 1704-62-7) to fish are available.

A static non-GLP 96 -h test on Golden orfe (Leuciscus idus) was conducted according to the German standard DIN 38412-15 (similar to OECD 203). The 96-hour LC50 was determined to be in the range between 320 mg/L without pH-adjustment(nominal, BASF AG, Rep. no.: 10F0073/875039, 1987). However, the observed effects are considered to be due to a pH-shift in the test water at higher test item concentrations; after neutralization, no adverse effects were observed (96 -h LC50 > 464 mg/L, nominal):

The key study for acute toxicity to fish was performed using not-pH-adjusted test solutions. As the test substance causes a pH-shift to more alkaline conditions with increasing test substance concentrations, the highest test solution (464 mg/L) was also tested after pH-adjustment.

The test solutions without pH-adjustment showed initial pH values between 8.0 and 9.9. The acceptable pH range for fish is given in the OECD TG 203 as pH 6 to 8.5. This pH range is only kept in the control test solution, while the other test solutions showed initial pH values above 9.3 – 9.9 (after 1 hour of the test procedure). During the test procedure the pH values decreases up to 7.7 in the test solutions expect the highest test concentration of 464 mg/L. While no mortality was observed in the treatments with acceptable pH values after 24 h (100 – 215 mg/L), all or almost all fish died in the treatments with a high pH (≥ 464 mg/L). It should be emphasized that no fish died during an exposure of 96 h in the highest test concentration of 464 mg/L with adjusted pH (pH range: 6.4 – 8.6). Therefore, it must be concluded that the observed mortality is due to the pH shift, but not due to an inherent toxic effect of the test substance.

As a consequence, the fish toxicity data from the treatments without pH adjustment should not be considered in the assessment of 2-[2-(dimethylamino)ethoxy]ethanol (DMEE, CAS 1704-62-7) as otherwise pH-effects cannot be distinguished from the inherent toxicity of the substance to fish. According to OECD TG 203, testing should be performed without adjustment of pH, unless there is evidence of marked change in the pH of the test medium after addition of the test substance. In the latter case, the pH of the stock solution of the test substance should be adjusted prior to addition to the test medium. Therefore, only the results from the pH-adjusted treatment with 464 mg/L DMEE should be considered for the assessment of acute toxicity to fish.

The test concentrations were not analytically verified. However, the substance proved to be stable in other studies (e.g. see IUCLID Chapter 6.1.3 and 6.1.5); in addition, the substance is assumed to be stable due to the substance's water solubility (e.g. see IUCLID Chapter 4.8), its low vapor pressure (VP = 11 Pa @ 20°C, meas.; BASF AG, 2005) and its low Henry's Law Constant (HLC = 2.79e-06 Pa m³/mol, estimated; BASF SE, 2019). Moreover, it is concluded, that significant adsorption is not expected for the substance (log Koc at pH 7 = 1.59, estimated; BASF SE, 2019).

Based on these available experimental results DMEE is considered to be with high probability acutely not harmful to fish.