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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
Study period:
22/11/1999 - 10/02/2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
1984
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: solid

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
After 24, 48, 72, and 96 hours of exposure, small volumes of the test media and the control were taken out to determine cell densities.

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Species: Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum)
Strain: SAG-61.81
Laboratory culture: Yes
Method of cultivation: Cultured under standardised conditions according to the test guidelines.
Pretreatment: Not reported
Initial cell concentration: Approximately 104 cells/ml.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Post exposure observation period:
none

Test conditions

Hardness:
0.24 mmol/L (= 24 mg/L) as CaCO3
Test temperature:
22 - 23ºC
pH:
8.1 - 8.2
Dissolved oxygen:
Not reported
Salinity:
Not applicable
Nominal and measured concentrations:
See table below:Nominal and measure concentrations
Details on test conditions:
Light intensity: Mean 8400 Lux (range: 7900 to 9000 Lux)
Photoperiod: Continuous illumination
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Remarks on result:
other: The 96-hour EC50 for the algal biomass b and growth rate µ could not be quantified due to the absence of any dinotefuran toxic effect at the tested concentrations.
Details on results:
No difference was observed between the algae growing in the test concentration of 100 mg/L and the algal cells in the control at the microscopic examination of the algal cell shape after 96 hours test period. The shape of the algal cells growing up to this concentration was obviously not affected.
The control cell density increased from nominal N = 1 x 104 cells/mL at the start of the test (0 hours) to N = 179 x 104 cells/mL (mean value) after 72 hours. As a result, the algal growth in the control was sufficiently high under the test conditions, and the validity criterion of increase by at least a factor of 16 was fulfilled. The cell density further increased to N = 350 x 104 cells/mL (mean value) at the end of the test (96 h).

There were no remarkable test media appearance observations. Throughout the test period, all test media were clear solutions. The test media and the control pH values were between 8.1 and 8.2 at the start and the end of the test.

See Table 1.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
- The EbC50 and EµC50 and the corresponding EC10 and EC90 and their 95%-confidence limits could not be calculated due to the absence of a toxic effect of the test item.
- The LOEC and the NOEC were determined directly from the mean biomass and the mean growth rates

Any other information on results incl. tables

Nominal and measure concentrations

Nominal test

Concen-tration (mg/L)

Sample date

 

 

(day)

Sample

Age

 

 

(hours)

Measured Concent-ration

 

(mg/L)1

% of Nominal

Mean Measured Concentration

 

(mg/L)

Mean Measured % of Nominal

100

0

0

0

0

99.5

99.7

100

100

99.6

100

4

4

96

96

95.2

95.9

95

96

95.6

96

Table 1:          Cell concentration data

Test-Substance

Nominal Concentration

[mg/l]

Mean density of algal cells (cell number x 10,000/mL) after:

Number

            24 h                          48 h                          72 h                          96 h

Control

7.33

40.07

179.43

349.00

6.25

6.13

33.08

154.45

320.30

12.5

7.45

39.38

192.28

350.47

25

7.28

39.42

189.72

339.68

50

7.10

36.87

175.02

318.80

100

7.30

39.27

185.22

311.40

Temperature [ºC]

22

23

23

23

pH

8.1 – 8.2

8.1 – 8.2

8.1 – 8.2

8.1 – 8.2

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Dinotefuran did not significantly inhibit the growth of Pseudokirchneriella subcapitata during the exposure period of 96 hours up to and including the nominal test concentration of 100 mg/L. This concentration was determined as the 96-hour NOEC (highest concentration tested without toxic effects after a test period of 96 hours). The 96-hour LOEC (lowest concentration tested with toxic effects), and the 96-hour EC50 for the algal biomass b and growth rate µ could not be quantified due to the absence of any dinotefuran toxic effect at the tested concentrations. However, these parameters were clearly higher than 100 mg/L.