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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:
23 May - 25 Oct 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
(Adopted:23 March 2006, Annex 5 corrected: 28 July 2011)
Deviations:
no
Qualifier:
according to
Guideline:
other: Testing Methods for New Chemical Substances; 2011.03.31, No. 0331-07, Ministry of Health, Labor and Welfare; 2011.03.29 No 5, Ministry of Economy, Trade and Industry; No. 110331009, Ministry of Environment, Japan; IV. Algae growth inhibition test.
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): [trade name given]
- Physical state: white crystalline powder
- Analytical purity: 100%
- Lot/batch No.: KNC110310
- Expiration date: 14 Mar 2014
- Stability under test conditions: stable for 3 years in ambient temperature

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: control, 100 mg/L
- Sampling method: An aliquot was taken from the remaining unused test solution of each test group at initiation and termination of the test. The samples were taken from mid-depth of each replicate without agitation.

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A 0.0802 g aliquot of the test substance was weighed. A stock solution of concentration 100 mg/L was prepared to make a volume to 800 mL with the medium.
- Eluate: no
- Differential loading: no
- Controls: yes, test medium control

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- Strain: ATCC22662
- Source (laboratory, culture collection): in-house culture originates from American Type Culture Collection (received 01 Aug 1996)
- Method of cultivation: aseptic culture

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Test temperature:
21.7 - 23.5 °C
pH:
7.6 - 7.7 at the begining
8.1 - 8.3 at the end
Nominal and measured concentrations:
nominal: 0, 100 mg/L
measured: < LOQ, 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 300 mL Erlenmeyer flasks with an air-permeable silicone stopper
- Volume of test solution: 100 mL/vessel
- Aeration: continuously shaken at 100 rpm
- Initial cells density: 1 x 10^4 cells/mL
- Control end cells density: 1.77 x 10^6 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Standard medium used: yes (OECD 201 recommended test medium)

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous fluorescent illumination
- Light intensity and quality: cool-white light, 400-700 nm, 60-120 µE/m²/s (± 15%) at the surface of the cultures

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: electronic particle counter after 24, 48 and 72 h
- Appearance: once daily
- Morphological changes: microscopic observation at the end of the test

- Range finding study
- Test concentrations: 0, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: 3.7% inhibition of growth rate at 10 mg/L, 2.3% inhibition of growth rate at 100 mg/L.
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): not reported
- Unusual cell shape: not reported
- Colour differences: not reported
- Flocculation: not reported
- Adherence to test vessels: not reported
- Aggregation of algal cells: not reported
Reported statistics and error estimates:
Student t-test

Any other information on results incl. tables

Table 1: Growth inhibition rates

Nominal concentration [mg/L]

Vessel No.

Growth rate 0 - 72 h [day -1]

Percent inhibition [%]

Medium control

1

1.7337

-

2

1.7124

-

3

1.7293

-

4

1.7244

-

5

1.7355

-

6

1.7213

-

Mean

1.7261

-

SD

0.0086

-

CV

0.5

-

100

1

1.6741

3.0

2

1.7172

0.5

3

1.7003

1.5

4

1.6884

2.2

5

1.7179

0.5

6

1.7120

0.8

Mean

1.7016

1.7*

SD

0.0176

-

* Statistically different

 

It is considered that the significant difference at 100 mg/L was not the results of the test substance treatment but of incidentally small relative variation between replicates of each test group. Although statistical significance was detected, the difference in the growth inhibition rate between 100 mg/L and control group was very small and was not considered biologically relevant. The statistical significance should be attributed not to the treatment of test substance but to the incidentally small relative variation of the values between replicates in each test group."

Applicant's summary and conclusion