Dimethyl (p-methoxybenzylidene)malonate

Endpoint summary

Description of key information

Acute aquatic toxicity

Algae: 72h-EC50 (Desmodesmus subspicatus, growth rate) = 9.3 mg/L, 72h-EC10 (Desmodesmus subspicatus, growth rate) = 0.963 mg/L (nominal)

Daphnia: 48h-EC50 (Daphnia magna, immobilisation) = 1.68 mg/L, 48h-NOEC (Daphnia magna, immobilisation) = 1.25 mg/L; 48h-LOEC (Daphnia magna, immobilisation) = 2.50 mg/L (nominal)

Fish: 96-LC50 (Danio rerio) > 1.23 mg/L (geom. mean measured)

STP microorganisms

3h-EC10 (activated sludge, total respiration inhibition) = 33.7 mg/L, 3h-EC50 (activated sludge, total respiration inhibition) > 1000 mg/L (nominal)

Additional information

Acute aquatic toxicity

Toxicity studies for the submission substance were available for three trophic levels, i.e. algae, daphnia and fish. The most sensitive organisms were aquatic invertebrated (Daphnia magna). All studies were considered reliable and adequate for the environmental hazard assessment for aquatic organisms.

Algae

In a reliable key study, toxicity of the submission substance to the green alga was determined according to OECD 201 (2011) and in compliance with GLP (RL1). The study was conducted with five test concentrations (nominal 0.0632, 0.200, 0.632, 2.00,  6.32 and 20.0 mg/L) under static conditions during 72 hours. Adverse effects on growth rate and yield of biomass followed a dose-response relationship. Derived effect concentrations on growth rate (r) and yield of biomass (y) were (nominal): 72h-ErC50 = 9.30 mg/L, 72h-ErC10 = 0.963 mg/L (OECD 201, 2017), 72h-NOErC = 0.632 mg/L; 72h-EyC50 = 1.11 mg/L, 72h-NOEyC = 0.200 mg/L (EC10 was not derived for yield of biomass).

Daphnia

In a reliable key study, acute immobilisation of Daphnia magna caused by the submission substance was determined according to OECD 202 (2004) and in compliance with GLP (RL1). The study was conducted with five test concentrations (nominal 10, 5, 2.50, 1.25, 0.625 mg/L) under static test conditions during 48 hours. The test concentrations and control were analytically verified by HPLC-DAD analysis. Observed effects followed a dose-response relationship with no effect the lowest test concentration (0.625 mg/L), first occurrence of immobilisation at 1.25 mg/L and complete immobilisation at highest tests concentration (10 mg/L). Derived effect concentrations were (nominal): 48h-EC50 = 1.68 mg/L (95 % confidence limits: 1.38 - 2.05 mg/L), 48h-NOEC = 1.25 mg/L and 48h-LOEC = 2.50 mg/L.

Fish

Acute toxicity of the submission substance to fish (zebrafish) was determined according to the OECD 203 (1992) and in compliance with GLP (RL1). A nominal test concentration of 2.00 mg/L (corresponding to 1.23 mg/L geom. mean measured) was tested as a threshold concentration in a limit test under semi-static conditions during 96 hours. No mortality or sublethal effects were observed in the treatment group or control during exposure. The derived effect concentrations were therefore: 96h-LC50 > 1.23 mg/L, 96h-NOEC > 1.23 mg/L.

STP microorganisms

In a reliable key study, respiration inhibition of the submission substance on activated sludge was investigated according to OECD 209 and in compliance with GLP (RL1). The test was carried out with five test concentrations (3.2 - 10 - 32 - 100 - 320 - 1000 mg/L) under static conditions for three hours. Inhibition of total respiration followed a dose-response relationship. The submission substance was not toxic up to a concentration of >= 10 mg/L. The determined NOEC was therefore 10 mg/L. Further calculated effect concentrations were (nominal): EC10 = 33.7 mg/L, EC20 = 68.5 mg/L, EC50 / EC80 > 1000 mg/L. The study was considered reliable and adequate for the environmental hazard assessment for STP microorganisms.