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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
From July 30th to August 02nd, 2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Justification for type of information:
Justification for Read Across is reported in the endpoint summary and it is further detailed in the report attached to the IUCLID section 13.
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
not specified
Details on test solutions:
A stock solution was prepared diluting 156.5 mg/l of test item in demineralized water (giving a concentration of 125 mg/l).
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subspicatus CHODAT.
- Source: Collection of Culture Algae, Insitute of Plant Physiology of Gottingen University

ACCLIMATION
- Culturing media and conditions: the culture was kept in stock to 8 ° C. Three days before the start of the test was incubated at 8000 lux to promote exponential growth.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
21 ± 2 °C
Nominal and measured concentrations:
125 mg/l, nominal
Details on test conditions:
TEST SYSTEM
- Test vessel: 8 ml tubes open, agitated individually.
- No. of vessels per concentration: 3 replicates.
- No. of vessels per control: 3 replicates.

EFFECT PARAMETERS MEASURED
Determination of light absorption in the cuvettes at the beginning and end of the test period with spectrophotometer PU 8625 at λ = 440 nm against test batch without algae. In the ranges where the measured, the cell number and the optical density are proportional to each other.
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 125 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 125 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
The No Observed Effect Level at 72 hours resulted to be lower than 125 mg/l.

The factor 16 required in the control approach within 72 hours corresponds to a growth rate of 0.9. A growth rate of 1.40 was achieved.
The pH of the control batch should not change by more than 1.5 units; in the test, the change was 0.8 units.

Extinctions

Nominal conc. (mg/l) E (0h) E (24h) E (48h) E (72h)
0 6 54 193 386
0 6 55 205 392
0 6 50 161 351
120 6 20 92 230
120 6 12 97 233
120 6 17 94 229

Data obtained

Nominal conc. (mg/l) Biomass Growth rate Average of inhibition (%)
Value
Inhibition
Value
Inhibition
Biomass Growth rate
0 425.00 -3.03 1.41 -0.63 0! 0!
0 441.00 -6.91 1.41 -1.00
0 371.50 9.94 1.38 1.64
120 212.00 48.61 1.23 11.73 48.8 11.7
120 210.50 48.97 1.24 11.42
120 210.50 48.97 1.23 11.83
Conclusions:
ErC50 (72h) > 125 mg/l (nominal)
EbC50 (72h): 125 mg/l (nominal)
Executive summary:

Method

The influence of the test item on the growth of the green algal species Desmodesmus subspicatuswas investigated in a 72-hour test according to the OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test).

Result

ErC50 (72h) > 125 mg/l (nominal)

EbC50 (72h): 125 mg/l (nominal)

Description of key information

ErC50 (72h) > 125 mg/l (nominal)

EbC50 (72h): 125 mg/l (nominal)

Key value for chemical safety assessment

EC50 for freshwater algae:
125 mg/L

Additional information