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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Gelb LD 259
- Lot/batch No.: 0817VP01
- Analytical purity: 87.6 - 89.1 area %
- Physical state: solid

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Each test solution was prepared seperately. The test substance was added to 5 l test medium which was subsequently stirred for 5 minutes at 20 +/- 2 °C.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: CHODAT SAG 86.81
- Source (laboratory, culture collection): Collection of algal cultures in Goettingen, Germany)

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Test temperature:
24 °C
pH:
8.1 - 8.6 (control
7.8 - 8.5 (treatments)
Nominal and measured concentrations:
Nominal test concentrations (mg/l):
control, 10, 22, 46, 100 and 220
The analytically determined concentrations were within 20 % of the nominal concentration.
Analytically determined concentrations (mg/l):
10.1, 22.2, 46.5, 101.6, 225.4
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer vessels (250ml) set up in a controlled climate cabinet (Vötsch Industrietechnik GmbH Bioline (VB1014))
- Type (delete if not applicable): test vessels were plugged with a gaspermeable silicon sponge cap
- Fill volume: 50 ml
- Initial cells density: 300 cells/ml
- Control end cells density: 870000 cells/ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to OECD guideline No. 201


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: permanent illumination
- Light intensity and quality: artificial light, (OSRAM L25), average 6892 lux, wave length 400-700 nm



EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: microscopic cell counting in a Neubauer haemocytometer
Mean fluorescence was determined after 0, 24, 48 and 72 hours


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Results used to determine the conditions for the definitive study: EC50 (growth rate) > 100 mg/l
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
22 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 220 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
The ErC50(72h) of the reference substance potassium dichromate was 0.86 mg/l.
(Date of the last control experiment: 20 Jan 2009, project-no. 60E0063/043030)

Any other information on results incl. tables

Nominal concentration [mg/l]

Mean cell density (cells/ml) x 104at 72 h

% inhibition (as yield)

% inhibition (as growth)

0

87

0.0

0.0

10

83

4.63

1.04

22

82

5.79*

1.33

46

56

36.7**

10.1**

100

40

54.4**

17.3**

220

32

64.1**

22.5**

*p<=0.05; **p<=0.01

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In conclusion the 72h ErC50 for Gelb LD 6259 with Desmodesmus subspicatus were >220 mg/L based on the nominal concentration of the test substance and >224.4 mg/L based on the mean of analytically determined concentrations.
Executive summary:

The test substance inhibited algal growth in a concentration dependent manner. However this effect is likely due to the strong color of the test solutions imparted by the test substance. The OECD 23 guidance document recogbnizes that coloured substances can absorb light and thus limit photosynthetic growth of algal cultures proportionally to test substance concentration. Consequently, this physical effect on algal growth is difficult to distinguish from inherent toxicity. The experimental system in this study was modified slightly in order to compensate for the physical effect of color, however this confounding effect can not be completely eliminated. Hence, the results of this study should be interpreted judiciously.