Registration Dossier

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:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well conducted study by GLP-compliant Japanese laboratory. The test was conducted according to OECD guidelines.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
- Substance type:Colourless clear liquid
- Physical state:liquid
- Analytical purity:99.8%, GC tested.
- Impurities (identity and concentrations): 0.04% water, <0.02% CH3COOH.
- Purity test date:
- Lot/batch No.:WDK5104
- Storage condition of test material: stored in refrigerator

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test stock solution was prepared by dissolving the test substance in the culture medium (as given in the OECD guideline)
- Eluate: Filtration by using 0.45 micrometer membrane filters
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): 5 mg/L in test stock solution

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: algae
- Strain: Selanastrum Capricornutum ATC22662
- Source (laboratory, culture collection): American Type culture collection, Rockvile, USA.
- Age of inoculum (at test initiation):unknown
- Method of cultivation: aseptically subcultered in testing lab.

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not):same
- Any deformed or abnormal cells observed: no

Study design

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

Test conditions

Test temperature:
23°C +/- 2°C
pH:
pH was checked at start (8.1) and end (9.6 - 10.2) of the exposure.
Details on test conditions:
Cells of algae were added to preculture solution at unitl the cell density was 10,000 cells /mL.
After the test vessels were set to 23°C in the test apparatus, the start was initiated.
Cell density was checked after 24, 48 and 72 hours.
To do so, an aliquot was taken off each solution and counted using Coulter counter. Further details are given below.

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Basis for effect:
biomass

Any other information on results incl. tables

RS-Freetext:
Nominal concentrations in mg/L: 100, 316 and 1000 
Measured concentrations in mg/L: n. d. for control, 101 -
102 for the nominal concentration of 100, 302 - 326 for the
nominal concentration of 316, and 978 - 1030 for the nominal
concentration of 1000.

EbC50 (biomass; 0 - 72 hours)       :  > 1000 mg/L
ErC50 (growth rate; 24 - 48 hours)  :  > 1000 mg/L
ErC50 (growth rate; 24 - 72 hours)  :  > 1000 mg/L
NOEC (biomass)                    :  = 100 mg/L
NOEC (Growth Rate; 24 - 48 hours) :  >= 1000 mg/L
NOEC (Growth Rate; 24 - 72 hours) :  >= 1000 mg/L

Was control response satisfactory?: Yes (Cell density of 72
hours is over 100 times more than 0 hour, growth curves
indicated the logarithmic growth during the test.)
Statistical results: as described above

- Biological observations
Cell density at each flask at each measuring point: 

Nominal        Cell Density (x10E4 cells mL)     Growth 
Concentration        Means (S.D)               Inhibition
rate                                               (%)
(mg/L)                                          
Mean(S.D.)  0 hour  24 hour  48 hour   72 hour
Control    1.0(0.0) 6.1(0.7) 34.8(2.0) 123.8(2.8)   -
 100       1.0(0.0) 6.2(0.7) 36.7(0.9) 124.4(4.7) -2.17
 316       1.0(0.0) 5.7(0.6) 33.1(1.3) 108.7(4.9)  9.65
1000       1.0(0.0) 4.7(0.1) 27.9(0.8)  91.0(3.7)  24.7

Growth curves: Logarithmic growth until end of the test
- Reference substances (if used) - results: LC50 (72 hours)
= 0.358 mg/L for potassium dichromate

Applicant's summary and conclusion

Conclusions:
For the test solution of 316 mg/L and 1,000 mg/L, growth was slightly inhibited at the beginning, but similar to the control in the end.
For the 100 mg/L solution, growth was identical to the control. Therefore the NOEC is < 1000 mg/L.
Executive summary:

Algae growth inhibition induced my MPD was tested in a static 72h-test according to OECD 201A guidelines.

Only slight growth inhibition was observed at the beginning of the exposure at a MPD concentration c= 1,000 mg/L.

At the end of the test, similar algae growth was observed in all MPD concentration level vessels and the control vessel . Therefore the NOEC of MPD is < 1,000 mg/L.