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The key study selected for deriving the PNECaquatic freshwater is the acute test on Desmodesmus subspicatus, BASF AG, 1988. For the marine compartment the most sensitive endpoint was the LC50 of 45 mg/L after 48 hours of exposure determined for Acartia tonsa (TNO, 2002). The PNEC for the marine compartment is derived from the NOEC of the freshwater algae test since this was the most sensitive endpoint of all aquatic toxicity tests available. Data on the reproduction test with the marine crustacea (Acartia) is provided, but should not be taken into consideration for the risk assessment due to significant shortcomings of the test design.

With LC50 values of > 1000 mg/L freshwater and marine fishes (BASF AG, 1990 and TNO, 2002, respectively) were less sensitive compared to aquatic invertebrates and algae.

The test substance demonstrated low toxicity to microorganisms and therefore inhibition of the degradation ability of activated sludge is not anticipated when introduced in appropriately low concentrations.

Although supporting chemical analysis was not performed in any of the ecotoxicity studies, the test item concentrations can be assumed to have been stable over the exposure periods of the tests for several reasons:

MDEA is highly soluble in water; therefore, undissolved residues are not to be expected and were also not observed in the tests. In combination with the low vapour pressure (0.0031 hPa at 20 °C, see IUCLID Ch. 4.6) and the low Henry's Law constant (pH 5 to 9: 1.82E-09 to 5.90E-06 Pa m³/mol, see IUCLID Ch. 5.4.2) volatilisation is not to be expected. The low adsorption potential (pH 5 to 8: Koc = 38 to 43, see IUCLID Ch. 5.4.1) indicates that MDEA will not adsorb to the testing equipment or the test animals. Based on the abiotic control of the key biodegradation study, the maximum removal was 6% by day 7 (see IUCLID Ch. 5.2.1, BASF AG, 1993). Although the substance is readily biodegradable, the lag phase in the biodegradation studies was long compared to the exposure periods of the aquatic toxicity tests. In the OECD 301A test (IUCLID Ch. 5.2.1, key study, BASF AG, 1993), the lag phase was > 3 to < 7 days. In seawater, 5% removal was observed after 7d based on BOD (IUCLID Ch. 5.2.1, supp. study, BASF SE, 2011: OECD 306). In the MITI test removal after 28 d was low (7% ThOD, 23 TOC, 25% test material). Regarding the short exposure period (48 to 96 h), a relevant decrease of the test item concentrations (> 20%) is not to be expected.

Based on the properties of MDEA, it can be concluded that the test item concentrations remained within acceptable limits in the ecotoxicity studies.