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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Butyldiethanolamine_OECD 202: ErC50 (72 h) > 100 mg/L; NOErC (72 h) = 25 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
25 mg/L

Additional information

The toxicity of the substance BDEA (CAS 102 -79 -4) towards green algae (Pseudokirchneriella subcapitata) was determined according to OECD Guideline 201 in compliance with GLP.

Following a preliminary range-finding test, the test organisms were exposed to an aqueous solution of the test item at concentrations of 6.25, 12.5, 25, 50 and 100 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C. The test item formed an alkaline solution when dissolved in culture medium, particularly at the maximum concentration employed of 100 mg/L (pH 9.5). At the request of the Sponsor, in order to determine whether it was the alkaline nature of the test item which gave rise to the observed inhibition, an additional 100 mg/L test concentration was prepared whereby the pH was adjusted to 7.5 prior to inoculation with algae (three replicates). Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Multisizer Particle Counter.

Analysis of the test preparations at 0 and 72 hours showed measured test concentrations to range from 92% to 105% of nominal and so the results are based on nominal test concentrations only. The biological data obtained confirmed that whilst the adjustment of the pH of the 100 mg/L test preparation did result in a decrease in the percentage inhibition observed, this decrease was not significant enough to attribute the effects seen in the non-pH adjusted preparations to the alkaline nature of the test item alone. Given that the alkalinity of the test preparations was considered to be due to an intrinsic property of the test item, and that inhibition of growth was also observed in a test preparation where the pH had been adjusted, it was considered appropriate to calculate the results based on the non-pH adjusted test preparations only. Exposure of Pseudokirchneriella subcapitata to the test item gave an ErC50 (72 h) value of > 100 mg/L, ErC10 (72 h) of 48 mg/L, a NOErC (72 h) of 25 mg/L, an EyC50 (72 h) of 57 and a NOEyC of 25 mg/L. The results from the positive control with potassium dichromate were within the normal ranges for this reference item.