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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The 96 and 72 hour ErC50 values for growth inhibition of freshwater algae ranged between 0.03 - 0.049 mg a.i./L. The 96 and 72 hour EbC50 values for biomass ranged between 0.02 and 0.014 mg a.i./L. The ErC10 values for growth rate were 0.009 and 0.0144 mg a.i./L.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.03 mg/L
EC10 or NOEC for freshwater algae:
0.009 mg/L

Additional information

Toxicity of C12-C16 ADBAC to the freshwater algae Selenastrum capricornutum was determined over an exposure period of 96 hours according to OECD guidelines. The test was conducted at the nominal concentrations of 0.005, 0.015, 0.045, 0.136 and 0.407 mg/L (50.2% pure substance). Analytical determination was performed for the test substance. The EbC50and ErC50(0-96 hours) of the 50.2% pure test substance were 0.02 mg/L (approximately equivalent to 0.01 mg a.i./L; 0.02 - 0.03; 95% confidence limits) and 0.06 mg/L (approximately equivalent to 0.03 mg a.i./L; 0.06 - 0.07; 95% confidence limits), respectively. The ErC10 and EbC10 values were estimated to be 0.0114 and 0.002 mg a.i./L. The LOEC was 0.005 mg/L and the NOEC < 0.005 mg/L (equivalent to 0.0025 mg a.i./L) based on growth rate. Chemical analysis of duplicate samples taken at the beginning (96% recovery) and at the end (98% recovery) of the test indicated that the exposure concentrations were substantially achieved (Kroon AGM et al.,1996).

In another OECD guideline study, the toxicity of C12-C16 ADBAC to Selenastrum capricornutum was determined over an exposure period of 72 hours. The test was conducted at the nominal concentrations of 0, 3.7, 13, 24, 43, 136 and 431 µg a.i./L (50% pure substance). The test substance concentrations were determined at the start of the test and after 23, 47 and 71 hours of incubation. Algal growth was determined at 0, 23, 47 and 71 hours. The ErC50and EbC50(0-72 hours) of the 50% pure test substance were 49 µg/L (40 - 61; 95% confidence limits) and 14 µg a.i./L (11 - 22; 95% confidence limits), respectively. The NOEC determined from the results for the test substance was equal to or less than 1.2 µg/L based on growth rate. Test substance concentrations were found to be relatively stable during the test and the mean measured test substance concentrations of 0, 1.2, 5.1, 11, 22, 98 and 382 µg/L were used for calculation of effect parameters. Statistical assessment of data by application of parametric model indicated a significant effect on the growth rate only. The ErC10 was determined to be 0.009 mg a.i./L.

The ErC50value of 49 µg a.i./L was therefore assessed to best represent the effect of C12-C16 ADBAC on algal growth (Mayer Pet al.,2001).