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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
6.01. - 28.03.2006
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: According to OECD guideline under GLP
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
Not relevant
GLP compliance:
yes (incl. certificate)

Test material

Details on test material:
- Name of test material (as cited in study report):
- Physical state: liquid
- Storage condition of test material: At room temperature (at about 20 °C), in a tightly closed container
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not relevant

Sampling and analysis

Analytical monitoring:
Details on sampling:
- Concentrations: 100 mg/L
- Sampling method: duplicate samples were taken before start and after 72 hours from both the control and the test samples
- Sample storage conditions before analysis: All samples were deep-frozen (at about -20 °C) immediately after sampling.

Test solutions

Details on test solutions:
The test item (64.96 mg) was dissolved in iso-octane and made up to the mark in a 50 mL
volumetric flask to prepare a stock solution of 1299.2 mglL. Defined volumes of this stock
solution were diluted with iso-octane to obtain standard solutions of the test item in the range
of 0.650 to 130 mg/L. These solutions were used to calibrate the GC-system.
Treatment samples and control samples were thawed at 35" C (water bath) for two hours and
shaken manually to obtain homogeneous -- -- . sample solutions.
The samples were extracted two times with 100 mL of pentan. After addition of 2 mL isooctane
(keeper) the combined organic phases were evaporated to 2 mL using a rotary
evaporator (20 minutes in a 35°C water bath). The 2mL were transferred in a 20 mL
volumetric flask and made up to the mark with iso-octane.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
- Common name: Scenedesmus subspicatus
- Strain: No. 86.81 SAG
- Source (laboratory, culture collection): (SAG, Institute for Plant Physiology, University of Göttingen, Germany

- Culturing media and conditions (same as test or not): same as test

Study design

Test type:
Water media type:
Limit test:
Total exposure duration:
72 h
Post exposure observation period:
not applicable

Test conditions

0.24 mmol/L (= 24 mg/L) as CaC03.
Test temperature:
8.2 - 8.8
Dissolved oxygen:
no data
Nominal and measured concentrations:
nominal loading rate 100 mg/L, mean measured concentration 1.76 mg/L
Details on test conditions:
The test was started (0 hours) by inoculation of 10,000 algal cells per mL of test medium.
These cells were taken from an exponentially growing pre-culture that was set up four days
prior to the test under the same conditions as in the test. One day before the start of the test,
the pre-culture was diluted threefold to keep the algae in exponential growth.
The test design included three replicates of the single test concentration and six replicates of
the control. Volumes of 15 mL algal suspension for each replicate were continuously stirred by
magnetic stirrers in 50 mL Erlenmeyer flasks.
The flasks were covered with glass dishes. They were incubated in a temperature controlled
water bath at a temperature of 22-23 "C (Table 4), and continuously irradiated at a measured
light intensity of about 7300 Lux (mean value), range: 6610 to 7930 Lux (minimum and
maximum value of measurements at nine places distributed over the experimental area at the
surface of the test media). This illumination was achieved by fluorescent tubes, installed about 35 cm above the test flasks.
The test duration was 72 hours.
Reference substance (positive control):
potassium dichromate

Results and discussion

Effect concentrations
72 h
Dose descriptor:
Effect conc.:
> 100 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Any stimulation of growth found in any treatment: The mean algal cell density in the test medium was at all counting dates slightly higher than
that in the parallel control cultures
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- EC50: 72-h EC50 for the growth rate: 0.78 mg/L
Reported statistics and error estimates:
A statistical evaluation of the algal cell densities was not necessary since the mean algal cell
density in the test medium was at all counting dates similar to or even slightly higher than in
the control.

Any other information on results incl. tables

No remarks

Applicant's summary and conclusion

Validity criteria fulfilled:
In conclusion, Dihydro-C14-Aldehyde and its possible degradation products had no toxic effect
on the algae up to their solubility limit in test water under the present test conditions.
Executive summary:

The influence of the test item Dihydro-C14-Aldehyde on the growth of the green algal species

Scenedesmus subspicatus was investigated in a 72-hour static test according to the EU

Commission Directive 92/69/EEC, C.3, 1992, and the OECD Guideline No. 201, 1984).

Due to the low water solubility of the test item, a supersaturated dispersion of the test item with

a loading rate of 100 mg/L was continuously stirred at room temperature in the dark over three

hours. After the stirring period an oily film was present on the surface. Therefore, only a part of

the dispersion of the test item was taken out of the middle of the water column and filtered

through a membrane filter just before the preparation of the test media. This procedure was necessary to avoid a penetration, of the

oily film through the filter into the test medium. The undiluted filtrate with the maximum

concentration of dissolved test item was used as the only test medium. Additionally, a control

was tested in parallel. Thus, a limit test was performed according to the EU Commission

Directive 92169/EEC.

The test item concentration in the analyzed test medium samples amounted to 2.45 mg/L at

the start of the test. In this test medium, incubated under the conditions of the test during the

test period (but without algae), a decrease of the test item concentration was determined. At

the end of the test, a test concentration of 1.26 mg/L was found. This decrease of the

measured test item concentration was considered to be caused by a loss by adsorption onto

the glass surfaces or by degradation.

The biological results are based on the test item concentration of 1.76 mg/L (calculated as the

average over all measurements in the undiluted filtrate) and on the loading rate of 100 mg/L.

The test item Dihydro-C14-Aldehyde and its possible degradation products had clearly no

inhibitory effect on the growth of Scenedesmus subspicatus during the test period of 72 hours

at the loading rate of 100 mg/L (mean measured concentration of 1.76 mg/L).

The 72-hour NOEC (highest concentration tested without toxic effects after a test period of

72 hours) was determined to be at the loading rate of 100 mg/L. The NOEC might even be

higher but test item concentrations above the solubility limit of the test item in test water or

loading rates above 100 mg/L were not tested, according to the EU Commission Directive

92169/EEC. The 72-hour LOEC (lowest concentration tested with toxic effects after a test

period of 72 hours), and the 72-hour EC10 and EC50 were clearly higher than the loading rate

of 100 mg/L. These values could not be quantified, since the test item had no toxic effect on

the algae up to the highest test item concentration which could be dissolved in the test water

at a loading rate of 100 mg/L.

In conclusion, Dihydro-C14-Aldehyde and its possible degradation products had no toxic effect

on the algae up to their solubility limit in test water.