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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

In this study the test item was found to inhibit the growth of the freshwater green alga Desmodesmus subspicatus after 72 hours. The nominal NOEC-values for inhibition of growth rate and inhibition of yield after 72 hours were 40.0 and 16.0 mg/L, corresponding to geometric mean measured values of 4.40 and 2.20 mg/L, respectively. The nominal LOEC-values for inhibition of growth rate and inhibition of yield after 72 hours were 100 and 40.0 mg/L, corresponding to 15.5 and 4.40 mg/L, respectively. The nominal EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) with 95 % confidence intervals after 72 hours were > 100 and 59.5 (46.5 – 85.2) mg/L, corresponding to > 15.5 and 6.11 (4.90 – 10.4) mg/L, respectively. 
All effect levels are given based on nominal and geometric mean measured concentrations of the test item.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
50.5 mg/L

Additional information

The toxicity of the test item to the unicellular freshwater green alga Desmodesmus subspicatus was determined according to the principles of OECD 201.The aim of the study was to assess the effects on growth rate and yield over a period of 72 hours.

The study was conducted under static conditions with an initial cell density of 4910 cells/mL. Based on a preliminary test 5 concentration levels were tested in a geometrical series with a nominal dilution factor of 2.5: 2.56 - 6.40 - 16.0 - 40.0 - 100 mg/L, corresponding to geometric mean measured concentrations of 0.538 – 1.10 – 2.20 – 4.40 – 15.5 mg/L. Three replicates were tested for each test item concentration and six replicates for the control. Environmental conditions were determined to be within the acceptable limits.

The content of aluminium, component of the test item, of the test item concentrations and the control were analytically verified in the fresh media (0 hours, before and after separation phase) and old media (72 hours) with a validated aluminium test (Aluminium Nanocolor – photometric determination with Eriochromcyanin R, Macherey-Nagel). The measured concentration of the stock solution after homogenization was 105 % of the nominal value. After 3 hours of separation of the phases, the supernatant of the stock solution was used for preparation of the test concentrations. The measured concentrations of aluminium in the freshly prepared media were in the range of 14 – 40 % of the nominal value. After 72 hours the measured concentrations were in the range of 9 – 14 % of the nominal values. Details of the analytical method are presented in part 9. The analytical results are presented in Table 8. All effect values given are based on the nominal and the geometric mean measured test item concentrations.

NOEC, LOEC, EC - values and 95 % Confidence Intervals of the test item (0-72 hours)

                  based on nominal and geometric mean measured test item concentrations [mg/L]

Nominal

Geometric mean measured

Growth Rate Inhibition

NOEC

40.0

4.40

LOEC

100

15.5

ErC10

50.5 (43.1 – 86.7)

5.30 (4.64 – 10.8)

ErC20

69.9 (50.5 – 92.9)

7.14 (5.21 – 12.3)

ErC50

> 100

> 15.5

Inhibition of Yield

NOEC

16.0

2.20

LOEC

40.0

4.40

EyC10

26.3 (14.5 – 35.6)

3.21 (2.06 – 4.05)

EyC20

36.2 (22.5 – 67.3)

4.07 (2.80 – 8.09)

EyC50

59.5 (46.5 – 85.2)

6.11 (4.90 – 10.4)