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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Read-across with CAS 68411-81-4 (mean measured):
EC10 (72 h; growth rate) = 63.5 mg/L
EC50 (72 h; growth rate) > 127.5 mg/L
NOEC (72 h; growth rate) = 16.8 mg/L

Read-across with CAS 92908-35-5 (nominal):
EC50 (72 h; growth rate) = 165 mg/L
NOEC (72 h, growth rate) = 30 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:
127.5 mg/L
EC10 or NOEC for freshwater algae:
63.8 mg/L

Additional information

A toxicity study with the test substance in aquatic algae is not available, but two tests with structural analogue substances were performed. The results were evaluated in a weigt of evidance approach.

A freswater algae test with Scenedesmus subspicatus is available (RCC, 852787, 2004). The substance tested in algae (CAS number 68411-81-4) is very similar to the submission substance and is manufactured in the same way, namely the reaction of glyoxal, urea and formaldehyde followed by methylation using methanol. In the toxicity test on freshwater algae (Scenedesmus subspicatus) according to OECD 201 and compliant to GLP, the following effect concentrations (based on active ingredient, CAS 68411-81-4) had been determined (mean measured concentrations):
NOEC (72h; biomass, growth rate) = 16.8 mg/L;
LOEC (72h; biomass, growth rate) = 40.8 mg/L;
EC10 (72h; biomass) = 41.5 mg/L;
EC10 (72 h; growth rate) = 63.5 mg/L;
EC50 (72h; biomass) = 111.7 g/L;
EC50 (72h; growth rate) > 127.5 mg/L;

Additionally, a valid algae test according to OECD guideline 201 with the close structural analogue, Urea, reaction products with formaldehyde and glyoxal (CAS 92908-35-5; BASF, 60E0760/083552, 2010). In the study Pseudokirchnerella subcapitata was exposed to the analogue substance for 72 hours. Based on the algal growth rate an EC50 of 220 mg/L and a NOEC of 40 mg/L were determined at test termination. The results refer to the nominal test concentration based on substance mass without correction for purity. Corrected for active ingredient, the results were EC50 (72h) 165 mg/L and NOEC (72h) 30 mg/L, respectively.