Reaction mass of bis(oxiran-2-ylmethyl) terephthalate and tris(oxiran-2-ylmethyl) benzene-1,2,4-tricarboxylate

Toxicity to microorganisms

Description of key information

Toxicity to Activated Sludge in a Respiration Inhibition Test

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

320 mg/L

Additional information

The test material was directly dosed into each test flask and tap water was added. The test item was dissolved into the tap water as homogeneously as possible.

Total respiration:
In comparison to the inoculum controls the respiration rate of the activated sludge was only slightly inhibited for all test concentrations. The inhibition was 5.2% at a test concentration of 10 mg/L and 8.9% at a test item concentration of 32 mg/L. For the test item concentrations of 100 mg/L and 320 mg/L the inhibition rates were 5.9%, and -6.1%, respectively. The highest test concentration of 1000 mg/L resulted in an inhibition of 11.4%. Concentrations exceeding 1000 mg/L nominal were not tested.

Respiration without nitrification (Heterotrophic Respiration):
In comparison to the inoculum controls the respiration was slightly inhibited by 8.1%, 9.6% and 11.7% at test item concentrations of 10 mg/L, 32 mg/L and 100 mg/L, respectively. At the concentrations of 320 mg/L and 1000 mg/L the respiration rates were slightly inhibited by 0.7% and 19.5%.

The 3-hour EC₅₀for total respiration and the oxygen uptake due to nitrification could not be calculated, therefore it is assumed that the EC₁₀, EC₂₀and EC₅₀lie above the highest test concentration of 1000 mg/L. Therefore NOEC calculations were performed. The NOEC is established to be higher than or equal 320 mg/L.

For heterotrophic respiration only the 3-hour EC₁₀could be calculated and was 127.3 mg/L.