Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

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:
experimental study
Adequacy of study:
key study
Study period:
14 June 1999 to 18 June 1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
yes
Remarks:
modified for coloured test substance
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
modified for coloured test substance
Principles of method if other than guideline:
The test method was modified following a method developed by RCC Ltd to quantify the algicidal effect of colored test substances, but also the growth inhibition effect caused by reduced light intensities In the colored test solutions.
GLP compliance:
yes
Analytical monitoring:
no
Details on sampling:
- Concentrations: 1.0, 3.2, 10, 32 & 100mg/l
Vehicle:
no
Details on test solutions:
The test medium of the highest test item concentration of nominal 100 mg/l was prepared by dissolving 50 mg of the test item completely In 500 ml test water by stirring for 5 minutes. Adequate volumes of this Intensively mixed test medium were added to test water to prepare the test media of the following additional nominal concentrations: 32, 10. 3.2 and 1.0 mg/I. Additionally, a control was tested in parallel (test water without addition of the test item).
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
The test organism used for the study was Scenedemus subspicatus CHODAT, Strain No. 86.81 SAG, supplied by the "Sammlung von Algcnkulturen, Pflanzenphysiologisches Instltut der Universltat Gottingsn", D-37073 Gottingen. The algae had been grown in the RCC laboratories under standardized conditions according to the test guidelines
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
No post exposure observation
Hardness:
0.24 mmol/l (= 24 mg/l) as CaCO3
Test temperature:
22 deg C
pH:
At the start of the test, the pH values in the test media and the control were in the range of pH 8.0 to 8.1, at the end of the test pH values were measured between pH 8.3 and 8.7.
Dissolved oxygen:
No data
Salinity:
Not applicable
Nominal and measured concentrations:
The nominal test concentrations were 100, 32, 10, 3.2 and 1.0 mg/l and a control of test media only.

The test medium of the highest test item concentration of nominal 100 mg/l was prepared by dissolving 50 mg of the test item completely in 500 ml test water by stirring for 5 minutes. Adequate volumes of this intensively mixed test medium were added to test water to prepare the test media of the following additional nominal concentrations: 32, 10. 3.2 and 1.0 mg/I. Additionally, a control was tested in parallel (test water without addition of the test item). The test media were prepared just before the start of the test.

The test concentrations were based on the results of a range-finding test and on pre-experiments to the selection of suitable methods for the preparation of the test media. However, concentrations in excess of nominal 100 mg/l have not been tested in compliance with the Commission Directive 92/89/EC. The enlarged spacing factor of 3.2 between the test concentrations was chosen, since according to the results of the range-finding test a large concentration range had to hp tested in the definitive test.

The range-finding test and the pro-experiments to the selection of suitable methods for the preparation of tha test media were not performed in compliance with the GLP Regulations and therefore are excluded from the Statement of Compliance. However, the raw data, respectively copies of raw data of these tests will be archived under the RCC project number of the present study.
Details on test conditions:
The test was performed in Erlenmeyer flasks (50 ml), each with 15 ml algal suspension, continuously stirred by magnetic stirrers, 3 flasks per test concentration and fi flasks in the control. Each Erlenmeyer flask wag placed In a black cylinder, coated Inside with aluminum foil. The cylinders were covered with glass dishes, the dishes were covered with watch glass dishes to prevent evaporation.

The test included two experimental parts:

Experimental part A:

The algae grew in test media with dissolved test item In the Erlenmeyer flasks (five test concentrations and a control). All glass dishes above the cylinders contained purified water. Thus, the inhibition of algal growth In this experimental part was caused due to a real toxic effect of the test item and in addition to the reduced light intensities In the colored test media in the Erlenmeyer flasks

Experimental part B:

In this experimental part the glass dishes above the cylinders contained the colored test media with the same test concentrations as In part A, however without algae (3 replicates per teat concentration). In the Erlenmeyer flasks below, the algae grew in test water without test item (as in the control), however under changed light conditions due to the filter effect of tiie colored test media in the glass dishes. Thus, the growth inhibition in part B was caused due to light absorption only. Tha depth of the test media in the glass dishes was 4 mm, i.e. half the depth of the test media in the Erlenmeyer flasks, because the algae in the stirred test media stay in the statistical mean in this mean depth.

All flasks were incubated In a temperature controlled water bath at 22 deg C and continuously illuminated at a measured light intensity of about 8700 Lux (mean value; range: 8200 to 9500 Lux (minimum and maximum value of measurements at 9 places distributed over the experimental area.) The light intensity was measured just before the start of fhe test below the coating cylinders. This illumination was achieved by fluorescent tubes (Philips TLD 36W/640), installed above the algal flasks. The test vessels were labeled with the RCC project number and all necessary additional information to assure unmistakable identification.

The test duration was 72 hours.
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
Experimental part A

Experimental part A corresponds to the usual algal toxicity test. This means that the algal growth inhibition in this experimental part was caused by a possible toxic effect of the test item and/or by the reduced light intensities due to the light absorption in the coloured test media.
In experimental part A, the test Item had a statistically significant Inhibitory effect on the growth rate μ and the biomass b of Scenedesmus subspicatus after the exposure period of 72 hours first at the concentration of 10 mg/l. Thus, 10 mg/l wore determined as the lowest concentration tested with inhibitory effects after the 72-hour test period. The highest concentration tested without inhibitory effects after a test period of 72 hours was determined at 3.2 mg/l, since up to and including this test Concentration the mean growth rata μ and the biomass b of the algae were statistically not significantly lower than in the control.

At the microscopical examination of the shape of the algal cells after 72 hours incubation period no difference was observed between the algae growing in the test item concentration of 10 mg/l In experimental part A and the algal cells in the control. Thus, the shape of the algal cells, growing at this concentration of dissolved test Item was obviously not affected.

Experimental part B

In experimental part B the algal growth Inhibition caused by the pure light effect (the reduced light intensities in the coloured test media) was quantified. In this experimental part a nearly identical Inhibition effect on the algal growth was observed compared to experimental part A.

The algal growth was statistically significantly reduced compared to the control after 72 hours test period first at the test concentration of 10 mg/l. The EC values in experimental part D were in the same magnitude as the corresponding EC values in experimental part A.

Comparison between the results in experimental parts A and B

According to the recommendations of the Ad-hoc working group of experts on algal growth inhibition for the interpretation of test results of coloured substances the comparison between the results in experimental parts A and B was based on the growth rates.
The differences between the results of experimental parts A and B wars described for each test concentration as percentage inhibition of the growth rate μA (IμA) minus the percentage inhibition of the growth rate μB (IμB) after the 72 hours test period. At all test concentrations these differences were lower than 10%. As another measure of difference the quotient of the growth rates μA/μB was calculated for each test concentration. At all lest concentrations this quotient was at least 0.9 or higher.

Differences in growth rates up to the magnitude of 10% are accepted to be caused by pure chance In the used algal toxicity test. Thus, according to the recommendations of the Ad-hoc working group of experts on algal growth inhibition tests for coloured substances the differences between inhibition in experimental part A and B should be not higher than 10%, respectively the quotient μA/μB should be at least 0.9 or higher to accept that the inhibition curves of the growth rates μA and μB are essentially the same. At all test concentrations of this test the differences of the growth rates μA and μB are lower than 10% and the quotients μA/μB are at least 0.9.
Results with reference substance (positive control):
Not applicable.
Reported statistics and error estimates:
As discussed above under results.
Validity criteria fulfilled:
yes
Conclusions:
This modified algal test has clearly demonstrated that the observed growth inhibition effect of the-test item on Scenedesmus subspicatus was caused only by the indirect effect, the light absorption in the coloured test solutions. Thus, a real toxic effect of the test Item on the growth of Scenedesmus subspicatus can be excluded up to the highest test concentration of 100 mg/l.
Executive summary:

Study conducted to EU test guidance 92/69/EEC part C3 and OECD test guideline 201 in compliance with GLP.


EC50 > 100mg/l. The substance is not considered to be harmful to algae.

Description of key information

EC50 > 100mg/L. The substance is not considered to be harmful to algae.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

A study on algal toxicity was conducted in a modified toxicity study according to EU test guidance 92/69/EEC part C3 and OECD test guideline 201 in compliance with GLP.

This modified algal test has clearly demonstrated that the observed growth inhibition effect of the-test item on Scenedesmus subspicatus was caused only by the indirect effect, the light absorption in the coloured test solutions. Thus, a real toxic effect of the test item on the growth of Scenedesmus subspicatus can be excluded up to the highest test concentration of 100 mg/l.

EC50 > 100mg/L. The substance is not considered to be harmful to algae.