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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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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:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
For this endpoint a one-to-one read across was performed to a chemical similar compound of the same chemical class with a comparable phys. chem. profile and similar response in biological assays. The relevant study was performed according to GLP and the methods applied are fully compliant with OECD TG 201. A detailed read across justification is provided in chapter 13 of this dossier.
Reason / purpose:
read-across source
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Validity criteria fulfilled:
yes
Conclusions:
EC50 > 100 mg/L (nominal)
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 20, 2006 - March 23, 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Principles of method if other than guideline:
None
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
The water solubility was below the limit of detection. Therefore the concentration of the test material in water could not be determined and is thus given as nominal value.
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
The test medium (reconstituted water and test material) was freshly prepared. The calibrated flask with test material and vehicle, reconstituted water, was treated in an ultrasound bath for 1 hour. Subsequently, the preparation was stirred with a magnetic stirrer for further 23 hours. Afterwards, the preparation was filtered through a filter funnel with a pore size of 10-16 µm. The filtrate was used for the study.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
The test system used for this study was a green unicellular algae species, Desmodesmus subspicatus, strain No. SAG 86.81, supplied by the "Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen". This strain is recommended by international guidelines.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Hardness:
250 mg CaCO3
Test temperature:
21-22°C
pH:
start of exp.: 7.9+/-0.1
end of exp.: 9.6+/-1.6
Dissolved oxygen:
saturated
Salinity:
for details see composition of reconstituted water "details on test conditions"
Nominal and measured concentrations:
Nominal concentration of 100 mg/L (limit test); due to very low water solubility and the fact that the study was a limit test, no further analysis was initiated.
Details on test conditions:
The test medium (reconstituted water and test material) was freshly prepared. The light intensity was approximately 8000 Lux. The experimental part was started by inoculation of algae to the different groups so that the flasks contained about 10,000 cells/mL. The algae were taken from an exponentially growing pre-culture (growth rate 68.8) which was set up 3 days prior to the experimental part under the same conditions as in the final study.

Details on composition of the reconstituted water:

Macro-nutrients:
50.00 mg/L NaHCO3
18.00 mg/L CaCl2 x 2 H2O
15.00 mg/L NH4Cl
15.00 mg/L MgSO4 x 7 H2O
12.00 mg/L MgCl2 x 6 H2O
1.60 mg/L KH2PO4

Trace elements:
100.00 µg/L Na2EDTA x 2 H2O
80.00 µg/L FeCl3 x 6 H2O
415.00 µg/L MnCl2 x 4 H2O
185.00 µg/L H3BO3
7.00 µg/L Na2MoO4 x 2 H2O
3.00 µg/L ZnCl2
1.50 µg/L CoCl2 x 6 H2O
0.01 µg/L CuCl2 x 2 H2O

The pH of the reconstituted water after aeration is approximately 8.
Reference substance (positive control):
yes
Remarks:
potassium dichromate from separate study
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Results with reference substance (positive control):
Regularly, a positive control test to check the test system is carried out with potassium dichromate (no results provided in the study report).
Validity criteria fulfilled:
yes
Conclusions:
An aqueous preparation of 100 mg/L (nominal) of the test material revealed no toxic effect in the test system. Analytically, the 72 hours EC50 to Desmodesmus subspicatus could not be determined; it exceeded the maximum solubility of the test material in reconstituted water (< 0.06 mg/L).

Description of key information

This one-to-one read across uses data generated for a chemical similar compound. For this compound information is available from a study that was performed according to GLP and to OECD TG 201 study, giving a NOEC of > 100 mg/L (nominal). Thus no toxicological effect occurs up to the limit of water solubility.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

For this endpoint information from a GLP compliant OECD TG 201 study is available. The data were obtained for a chemical similar compound and used in a one-to-one read across.

Justification for read across

Type of read across:one-to-one

Based on:

(1) chemical similarity: both compounds share a bicyclohexyl core structure and differ in alkyl substitution pattern

(2) almost identical physicochemical profile

(3) same response in relevant biological assays

  

Assay

Test item

surrogate 

Appearance

solid

solid

Similarity Score (Dice)

1,0

1,0

Water solubility

< 0,004 mg/L

 <0,06 mg/L

logP

8,2

 4,4

Molar mass

236,4 g/mol

 264,5 g/mol

Melting point

65,7 °C

 97,1 °C

Boiling Point

323,7 °C

 352 °C

Vapour Pressure

0,024 Pa               

 0,0041 Pa
 Fish acute (OECD 203)  NOEC > 100 mg/L (nominal)  NOEC > 100 mg/L (nominal)
 Fish long term data (from OECD 305)  NOEC > 100 mg/L (nominal)  NOEC > 100 mg/L (nominal)