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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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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: Comparable to guideline study with acceptable restrictions (no analytical verification of test item concentrations; non-GLP)

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989
Reference Type:
study report
Title:
Unnamed
Year:
1996
Report Date:
1996
Reference Type:
other: statistical evaluation
Title:
Unnamed
Year:
2006
Report Date:
2006

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: German Industrial Standard DIN 38412, Part 9
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Methyl formate
- Analytical purity: 97%

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: stock solution of test substance: concentration: 100 mg/L of the test substance, conductivity: 18 µS/cm, pH 3.5; the stock solution was dil uted with test medium to yield the final test concentrations 

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subspicatus
- Strain: SAG 86.81
- Method of cultivation:
- test flasks: 250 ml-Erlenmeyer flasks plugged with gas permeable silicon-sponge caps
- test volume: 100 ml
- temperature: 20 °C
- flasks were incubated in an incubation chamber for 72 h
- flasks were shaken once daily to hold cells in suspension
- illumination: continuous artificial light
- light intensity: approx. 120 µE/(m2*s) 

ACCLIMATION
- Culturing media and conditions (same as test or not): according to DIN 38412, part 9; the medium is similar to that recommended in OECD TG 201

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
96 h

Test conditions

Test temperature:
23 °C
pH:
7.0 - 8.5
Nominal and measured concentrations:
Nominal: 0, 7.81, 15.63, 31.25, 62.5, 125, 250, and 500 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): 20 ml tubes plugged with gas permeable silicon-sponge caps (test was performed in non-sealed vessels)
- Material, size, headspace, fill volume: 10 ml
- Initial cells density: 10000 exponentially-growing cells per mL
- No. of vessels per concentration (replicates): 6; 1 blank per concentration (w/o cells)
- No. of vessels per control (replicates): 6


TEST MEDIUM / WATER PARAMETERS
- Conductivity: 18 µS/cm


OTHER TEST CONDITIONS
- Photoperiod: continuous artificial light
- Light intensity and quality: approx. 120 µE/(m2*s)


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Other:
- samples were taken at regular intervals (0, 24, 48, 72, 96 h)
- measurements: fluorescence (in vivo chlorophyll-a fluorescence at 685 nm as a size for the biomass [pulsed excitation with light flashes having a  wavelength of 435 nm]); pH at 0 h (w/o algae) and 96 h (w and w/o out algae)

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
7.81 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
131.2 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 95.0-162.8 mg/L
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
271.1 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 230.2-313.8 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1 079 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 819.9-1656 mg/L

Any other information on results incl. tables

The following nominal effect concentrations related to yield (EyC), growth rate (ErC), and biomass integral (EbC) were recalculated according to OECD TG 201 (adopted 23 Mar 2006) using the fluorescence values for inhibition of biomass from the original report. Since no calibration curve data were available, fluorescence data were equated with cell numbers (95 % confidence intervals in brackets):

Yield (mg/L)

72 h

96 h

NOEyC

7.81

31.25

EyC10

44.3 (16.8 -  70.9)

49.3 (28.6 -  68.4)

EyC20

77.3 (40.0 - 110.0)

78.8 (53.5 - 101.0)

EyC50

223.4 (167.0 - 316.6)

192.6 (158.7 - 236.3)

 

 

Growth rate (mg/L)

72 h

96 h

NOErC

7.81  

31.25

ErC10

131.2 (95.0 - 162.8)

128.9 (105.4 - 150.1)

ErC20

271.1 (230.2 - 313.8)

253.1 (227.1 - 278.6)

ErC50

1079.0 (819.9 - 1656.0) 

914.1 (771.0 - 1146.0)

 

         

Biomass integral (mg/L)

72 h

96 h

NOEbC

7.81

7.81

EbC10

53.2 (10.4 -  95.6)

49.0 (20.8 -  76.0)

EbC20

101.9 (37.4 - 156.6)

85.5 (47.9 - 118.4)

EbC50

351.2 (238.2 - 714.9)

246.2 (189.1 - 339.6)

 

Original effect values as given in the report

(nominal concentrations):

EC20 (72 h): 89.7 mg/l

EC50 (72 h): 235.3 mg/l

EC90 (72 h): > 500 mg/l

EC20 (96 h): 76.8 mg/l

EC50 (96 h): 204.8 mg/l

EC90 (96 h): > 500 mg/l


Algal growth compared to control (%):

Concentration (mg/L)

24 h

48 h

72 h

96 h

Control

100

100

100

100

7.81

92.6

91.8

96.5

94.2

15.63

82.7

83.5

86.2

92.4

31.25

109.3

100.5

92.2

99

62.5

109.3

95

87

83.4

125

101.8

86.2

70.9

68.4

250

93.9

74.4

47.2

39.6

500

91

57.9

24.7

19.2


pH values:

Concentration (mg/L)

pH without algae

pH with algae

 

0 h

96 h

96 h

Control

8.5

8.2

10.2

7.81

8.1

8.1

10.3

15.63

7.9

8.1

10.3

31.25

7.8

8.1

10.1

62.5

7.6

8.0

9.8

125

7.4

7.9

9.3

250

7.3

7.7

8.6

500

7.0

7.1

7.2

Applicant's summary and conclusion

Validity criteria fulfilled:
yes