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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1999-03-05 to 1999-07-05
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP study according to guideline.
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: nominal concentrations of 3 and 30 mg product/L were tested after 0, 24, 48 and 72 h.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Loadings with 1, 3, 10 and 30 mg of the test substance per liter test medium were stirred for about 24 hours. After settling time of about 2 hours all solutions were filtered through glass fibre filters, which were activated with NaOH and washed with deionised water before. Besides these filtrates used directly, two dilutions of the WAF with 1 mg/L loading were used for preparing nominal concentrations of 0.1 and 0.3 mg/L. At last all solutions were inoculated with algae and incubated.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Green algae
- Source (laboratory, culture collection): Pflanzenphysiologisches Institut der Universität Göttingen
- Age of inoculum: delivered on 1999-26-03

ACCLIMATION
- Acclimation period: about 3 to 4 days in test medium without test substance
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24.3 - 24.7°C
pH:
7.7 to 8.4
Nominal and measured concentrations:
Nominal: 0.1, 0.3, 1, 3, 10, 30 mg product/L
Measured concentrations after 72 hours for nominal concentrations 3 and 30 mg product/L were 0.08 and 0.1 mg product/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 300 mL conical flasks

- Material, size, headspace, fill volume: 100 mL fill volume

- Initial cells density: 10000 cells/mL
- Control end cells density: 1100000 cells/mL

- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3


GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: pH value was measured after 0 and 72 hours after test initiation. Temperature range was measured.

OTHER TEST CONDITIONS
- Photoperiod: continous uniform illumination
- Light intensity and quality: 2000 lux daylight-spectrum

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: coulter-counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3
- Range finding study: yes, was conducted from 1999-05-03 to 1999-05-07
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
17 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Results are based on nominal concentration due to use of WAFs
Duration:
72 h
Dose descriptor:
EL0
Effect conc.:
0.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Results are based on nominal concentration due to use of WAFs
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
0.86 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Results are based on nominal concentration due to use of WAFs
Details on results:
- Exponential growth in the control: yes

In a re-evaluation of the test additional parameter could be determined:

72 h              EC10       0.226 mg/l effect conc.       noninal       based on test mat.       growth rate

72h              NOEC       0.1 mg/l effect. conc.           nominal       based on test mat.       growth rate

Validity criteria fulfilled:
yes
Conclusions:
The substance is acutely harmful for aquatic plants.
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP study according to guideline.
Justification for type of information:
Being a tridodecylamine and a tri-C8,10-amine, target and source substance are structurally very similar only differing slightly in the length of the alkyl chain. Thus, both target and source subtance have identical functional group(s), common precursor(s)/breakdown product(s) as well as common mechanism(s) of action.
Reason / purpose:
read-across source
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
17 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Results are based on nominal concentration due to use of WAFs
Duration:
72 h
Dose descriptor:
EL0
Effect conc.:
0.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Results are based on nominal concentration due to use of WAFs
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
0.86 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: Results are based on nominal concentration due to use of WAFs
Conclusions:
Based on data for a suitable read across substance, one can assume that Tridodecylamine is toxic to freshwater algae.

Description of key information

EL50(72h) = 17 mg/L (nominal, loading rate) for growth rate of Desmodesmus subspicatus (OECD 201, read across)

Key value for chemical safety assessment

EC50 for freshwater algae:
17 mg/L

Additional information