Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
March 20, 2006 - March 23, 2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was performed in compliance with the Good Laboratory Practice (GLP) regulations (revised in 1997, ENV/MC/CHEM(98)17).The method followed that described in the OECD Guidelines for Testing of Chemicals (Adopted: 4 April 1984) No 201 "Alga, Growth Inhibition Test", adopted March 23, 2006. The test material shows a high similarity in chemical descriptors and physicochemical profile to the query compound providing a sound basis for read across.
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+/-0.1end 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 H2O185.00 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).
Executive summary:

Purpose

The purpose of this assay was to identify the aquatic toxicity potential the test material in algea to provide a rational basis for hazard estimation for the test item in aquatic environments.

Study design

The influence of the test material on the growth and growth rate of the green algae species Desmodesmus subspicatus was tested. The study design included one control and one test material group with six replicates, each containing about 100 rnL reconstituted water or test medium and 10,000 cells/mL at the start of the experimental phase. The algae were exposed to a filtrate of nominal 100 mg/L and the study was performed as a limit test in an open static test system. The growth was calculated after 24, 48, and 72 hours exposure in the test medium.

Results

The analysis of the saturated aqueous preparation revealed that the water solubility of the test material in reconstituted water was < 0.06 mg/L. The test material concentration in the aqueous medium could not be quantified since it was below the level of detection. For the test material, the following EC50 values and no effect concentration for Desmodesmus subspicatus were determined:

72 h EC50 > 100 mg/L (nominal)

72 h NOEC > 100 mg/L (nominal)

Conclusions

An aqueous preparation of 100 mg/L (nominal) of the test material revealed no toxic effect in the test system. The 72 hours EC50 exceeded the maximum solubility of the test material in reconstituted water.

Description of key information

For this endpoint, adequate information is provided from a read across to a GLP compliant OECD TG 202 study performed for a structural similar compound that shows a similar phys-chem. profile. The study performed for this compound gives a NOEC of 100 mg/L (nominal).

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

Justification for read across

Type of read across:one-to-one

Based on:

(1) chemical similarity

(2) almost identical physicochemical profile

(3) same response in biological systems relevant for the endpoint as shown below:

 

Assay

test item

surrogate (CAS 96624-52-1)

Appearance

solid

solid

Similarity Score

1

0.8

Water solubility

< 0.02 mg/L

0.06 mg/L

logP

> 5.7

4.4

Molar mass

234.4 g/mol

262.5 g/mol

Melting point

34.4 °C

97.1 °C

Boiling Point

329 °C

352 °C

Vapour Pressure

0.015 Pa               

0.0041 Pa

Fish Acute Toxicity

LC50 (96h) > 100 mg/L

LC50 (96h) > 100 mg/L

BCF

below 2000 (639)

below 2000 (56)

The NOEC (> 100 mg/L) observed for the surrogate is used as read across reference for the test item.