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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
72 hours, 4 to 7 March 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline and GLP-compliant study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Caprolactone Consortium (BASF, Daizel, Dow and Solvay)/ Batch number: U 05175
- Purity test date: 99.95 %

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Stability: unlimited. Stability of the test substance under storage conditions over exposure period was guaranteed by the sponsor and the sponsor holds this responsability
- Aggregate state/appearance: liquid /clear, colourless
- Water-solubility: soluble
- Homogeneity: homogeneous (sponsor data)

Analytical monitoring:
yes
Details on sampling:
Samples were taken at 0 hours (fresh media) and 72 hours (expired media).
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test substance was stirred in deionised water for about 10 minutes at approximately 20 ± 2 °C.
- The nominal concentration of the stock solution was 5000.2 mg/I . By diluting this stock solution the following nominal concentrations (mg/I) were prepared: control, 4000, 1600, 640, 256 and 102 mg/l
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): The stock solution appears clear and colourless
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name:
- Strain: CHODAT SAG 86.81
- Source (laboratory, culture collection): SAG (Collection of algal cultures in Göttingen)

Pre-culture techniques
- Seed-culture: a seed culture was incubated for 4 days at 23 °C ± 2 °C. Final cell density: 89 x 10-4 cells/ml
- Pre-culture: seed-culture was taken to inoculate pre-culture (initial cell density: 1 x 10-4 cells/ml}. The pre-culture was incubated for 3 days at 23 °C ± 2 °C. Final cell density: 126 x 104 cells/ml.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
none
Post exposure observation period:
not applicable
Hardness:
Not applicable
Test temperature:
23 ± 2 °C
pH:
6.9 - 8.2
Dissolved oxygen:
Not applicable
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal: 102, 256, 640, 1600, 4000 mg/L
Measured (mean of 2): 93, 260, 664, 1693, 4204 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks (nominal volume 250 ml) plugged with gas permeable siliconsponge caps
- Test volume: 100 ml
- Initial cells density: 1 x 104
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement:
- Measurement of temperature: continuously during the whole test period in the climate chamber
- Measurement of pH-values: after 0 h and 72 h in an additional uninoculated replicate and after 72h in the inoculated replicate

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Light intensity and quality: about 60 - 120 uE/(m2s) at a wave length of 400 - 700 nm. Artificial light, type universal white (OSRAM L 25), permanent illumination.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: after 72 h in a counting chamber (Neubauer improved) from a control vessel
- Chlorophyll measurement: in vivo chlorophyll-a-fluorescence (pulsed excitation with light flashes having a wavelength of 435 nm)
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1 217 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2 616 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
256 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: biomass and growth rate
Details on results:
none
Reported statistics and error estimates:
Calculation of the integral of biomass growth over the total duration of the test for each concentration level and comparison of values of treated samples in relation to untreated samples.
Calculation of the growth rate over the total duration of the study for each concentration level and comparison of values of treated samples in relation to untreated samples.
The EC values were calculated (linear regression analysis) from the concentration-response relationship.
The LOEC was determined by comparing the means of the calculated biomass or growth rate of the various concentration levels with the control. The Dunnett's One-tailed T test was carried out at a 95% significance level.
The NOEC is the tested concentration immediately below the LOEC.

Results of the definitive test are compiled below:

Measured fluorescence (relative units)

Time (h)

Flask number

Concentration (mg/L)

0 (control)

4000

1600

640

256

102

0

1

30

31

31

32

31

33

2

31

32

34

33

31

35

3

30

32

32

31

31

34

no

0

0

0

0

0

0

24

1

130

98

130

130

150

130

2

130

95

130

140

140

140

3

130

95

130

140

150

140

no

0

0

0

0

0

0

48

1

660

180

440

630

730

660

2

700

190

420

670

750

680

3

680

190

430

660

780

680

no

0

0

0

0

0

0

72

1

3450

170

930

2720

3330

3380

2

3500

150

780

2450

3800

3590

3

3180

150

730

2350

3970

3630

no

0

0

0

0

0

0

no = not inoculated

Cell density after 0 h, 24 h, 4$ h and 72 h

Time (h)

Flask number

Concentration (mg/L)

0 (control)

4000

1600

640

256

102

0

1

1.5

1.6

1.6

1.6

1.6

1.7

2

1.6

1.6

1.7

1.7

1.6

1.8

3

1.5

1.6

1.6

1.6

1.6

1.7

mean

1.5

1.6

1.6

1.6

1.6

1.7

24

1

6.6

5.0

6.6

6.6

7.6

6.6

2

6.6

4.7

6.6

7.1

7.1

7.1

3

6.6

4.8

6.6

7.1

7.6

7.1

mean

6.6

4.9

6.6

7.0

7.5

7.0

48

1

33.6

6.2

22.4

32.1

37.2

33.6

2

35.7

9.7

21.4

34.2

38.2

34.7

3

34.7

9.7

21.9

33.6

39.8

34.7

mean

34.7

9.5

21.9

33.3

38.4

34.3

72

1

175.9

8.7

47.4

138.7

169.8

172.3

2

178.4

7.6

39.8

124.9

193.7

183.0

3

162.1

7.6

38.7

119.8

202.4

185.1

mean

172.1

8.0

42.0

127.8

118.6

180.1

Calculation of biomass and inhibition of biomass after 72h

Parameter

Flask number

Concentration (mg/L)

0 (control)

4000

1600

640

256

102

Biomass (rel)

1

124

15

49

104

126

122

2

128

14

44

100

138

129

3

119

14

44

97

145

130

mean

120

14

45

100

136

127

Inhibition (%)

 

0.0

88.4

63.2

19.0

-10.3

-2.9

 

Calculation of growth rate and inhibition of growth rate after 72h

Parameter

Flask number

Concentration (mg/L)

0 (control)

4000

1600

640

256

102

Growth rate (rel)

1

0.066

0.024

0.047

0..062

0.065

0.064

2

0.066

0.021

0.044

0.060

0.067

0.064

3

0.065

0.021

0.044

0.060

0.067

0.065

mean

0.065

0.022

0.045

0.061

0.066

0.064

Inhibition (%)

 

0.0

66.1

31.4

7.5

-1.4

1.4

 

Validity criteria fulfilled:
yes
Conclusions:
The 72-hour ErC50 (growth rate), EbC50 (integrated biomass) for D. subspicatus exposed to the test material under static conditions were 2616 and 1217 mg/L, respectively. The NOEC for biomass and growth rate was 256 mg/l.
Executive summary:

Desmodesmus subspicatus was exposed to test material at nominal concentrations of 102, 256, 640, 1600 and 4000 mg/L in a static 72 -hour toxicity test carried out according to OECD 201 guidelines. The study was reliable (Klimish 1) and conducted by GLP standards. The test design included an untreated control comprising untreated algal growth medium only. Analytical concentrations were verified at test initiation and termination (72h) and measured concentrations were 91 - 106% of nominal. The 72 -hour ErC50 and EbC50 endpoints determined were 2616 and 1217 mg/L, respectively. The corresponding 72hr NOEC, based on inhibition of specific growth rate or inhibition of biomass was 256 mg/L.

Description of key information

The 72-hour ErC50 (growth rate), EbC50 (integrated biomass) for D. subspicatus exposed to the test material under static conditions were 2616 and 1217 mg/L, respectively. NOEC for biomass and growth rate was 256 mg/l.

Key value for chemical safety assessment

EC50 for freshwater algae:
1 217 mg/L
EC10 or NOEC for freshwater algae:
256 mg/L

Additional information

Desmodesmus subspicatuswas exposed to test material at nominal concentrations of 102, 256, 640, 1600 and 4000 mg/L in a static 72 -hour toxicity test was carried out according to OECD 201 guidelines. The study was reliable (Klimish 1) and conducted by GLP standards. The test design included an untreated control comprising untreated algal growth medium only. Analytical concentrations were verified at test initiation and termination (72h) and measured concentrations were 91 - 106% of nominal. The 72 -hour ErC50 and EbC50 endpoints determined were 2616 and 1217 mg/L, respectively. The corresponding 72hr NOEC, based on inhibition of specific growth rate or inhibition of biomass, was 256 mg/L.