Acetic acid, oxo-, sodium salt, reaction products with ethylenediamine and phenol, iron sodium salts

Toxicity to aquatic algae and cyanobacteria

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:

2010-04-28 to 2010-06-30

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The test substance inhibited algal growth in a concentration dependent manner, however, the test solutions were also colored by the test substance. The OECD 23 guidance document acknowledges that colored substances can absorb light and thus limit photosynthetic growth of algal cultures proportionally to test substance concentration. Consequently, the experimental system in this study was modified (i.e. increased light intensity, shortened light path, reduced inoculation density, and constant shaking) in order to compensate for the physical effect of color. These modifications are recommended in OECD 23, however the physical effect of color may not be completely eliminated.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acetic acid,oxo-,sodium salt (FeNaEDDHA)
-Synonym: Acetic acid,oxo-,sodium salt, reaction products with ethylenediamine and phenol,iron sodium salts
- Physical state: Solid/ red, dark
- Analytical purity: 100 % (UVCB)
- Lot/batch No.: 09226BR8
- Expiration date of the lot/batch: 07 Mar 2012
- Storage condition of test material: At ambient temperature under exclusion of light

Analytical monitoring:

yes

Details on sampling:

Sampling was performed at the start of the exposure (0 h) from the inoculated replicate
7 of each concentration and the control. At the end of the exposure (72 h) samples of the inoculated replicates 1-3 of the test concentrations and of the inoculated replicates 1- 6 of the control group were taken. The replicates were combined before sampling. All samples were placed into glass sample vials and covered with aluminium foil for light protection.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The test solutions were prepared separately for each test concentration (differential loading). The solutions were stirred for approx. 10 min under light exclusion.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Test species and strain: Desmodesmus subspicatus CHODAT (SAG 86.81)
- Source (laboratory, culture collection): Collection of algal cultures in University of Göttingen/Germany
- Age of inoculum (at test initiation): A stock algal culture is maintained continuously at the test facility. Before the exposure an inoculum culture is prepared from the stock culture and incubated for 4 days at 21 – 24 degree C (max. temperature difference 2 degree C). After this time, the inoculum culture is in exponential growth phase and can be used to initiate the test (study day 0).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23.1 – 23.5 degree C

Nominal and measured concentrations:

Nominal: 3.2, 10, 32, 100, 320 mg/L
Measured: The analytically determined concentrations of the test substance in the test water were in a range of 89 - 102% of the nominal concentration at start of exposure and decreased to 63 - 86 % of the nominal concentration at the end of exposure. Therefore mean measured concentrations were considered to be an accurate representation of exposure levels throughout the exposure period.

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks (nominal volume 250 mL) plugged with gas permeable silicone sponge caps
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6


GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity and quality: Average 8144 lux (within ± 15% variability) at a wave length of 400 - 700 nm.



TEST CONCENTRATIONS
- Range finding study
The results of the 72 hour range finding test were:
EC50 fluoresence = 46.1 mg/L; ErC50 > 100 mg/L (nominal).

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 293 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

8.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

29.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

27.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

8.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Results with reference substance (positive control):

According to the test ISO guideline 8692 the EC50 values of the reference substance potassium dichromate should be in the range: ErC50 = 0.71 – 0.97 mg/L after 72 hours for Desmodesmus subspicatus. The ErC50 (72 h) of the control substance potassium dichromate was 0.82 mg/L.
These results indicate that the algae are responding normally to toxicant stress.

Validity criteria fulfilled:

yes

Conclusions:

In conclusion the 72 hour EC50 value for FeNaEDDHA with Desmodesmus subspicatus CHODAT (SAG 86.81) was > 293 mg/L and the NOEC was 8.1 mg/L based on algal growth rate. The 72 hour EC50 based on yield was 27.2 mg/L and the NOEC 2.4 mg/L.

Executive summary:

The toxic effects of FeNaEDDHA on the growth of single-cell green algae as representatives of primary producers in freshwater plankton over a 72 hour static exposure period were determined according to the principles of OECD-Guideline 201 and EU method C.3.

The following nominal concentrations based on test substance mass without a correction for purity were used: 3.2, 10, 32, 100, 320 mg/L. The analytically determined concentrations of the test substance in the test water were in a range of 89 - 102% of the nominal concentration at start of exposure and decreased to 63 - 86 % of the nominal concentration at the end of exposure. Therefore mean measured concentrations were considered to be an accurate representation of exposure levels throughout the exposure period.

The 72 hour EC50 value for FeEDDHA with the Desmodesmus subspicatus CHODAT (SAG 86.81) was greater than 293 mg/L and the NOEC was 8.1 mg/L based on mean measured concentrations and growth rate. The 72 hour EC50 based on yield and mean measured concnetrations was 27.2 mg/L and the NOEC was 2.4 mg/L.

Description of key information

EC50(72h) > 294 mg/L (geom. measured) for growth rate of Desmodesmus subspicatus (OECD 201)

NOEC(72h) = 8.2 mg/L (geom. measured) for growth rate of Desmodesmus subspicatus (OECD 201)

Additional information

In a key study the the toxic effects of FeNaEDDHA on the growth of single-cell green algae as representatives of primary producers in freshwater plankton over a 72 hour static exposure period were determined according to the principles of OECD guideline 201 and EU method C.3. The following nominal concentrations based on test substance mass without a correction for purity were used: 3.2, 10, 32, 100, 320 mg/L. The analytically determined concentrations of the test substance in the test water were in a range of 89 - 102% of the nominal concentration at start of exposure and decreased to 63 - 86 % of the nominal concentration at the end of exposure. Therefore mean measured concentrations were considered to be an accurate representation of exposure levels throughout the exposure period. The 72h-EC50 value for growth rate of Desmodesmus subspicatus is determined to be > 293 mg/L and the 72h-NOEC is determined to be 8.1 mg/L based on geometric mean measured concentrations.

The test substance inhibited algal growth in a concentration dependent manner, however, the test solutions were also colored by the test substance. The OECD 23 guidance document acknowledges that colored substances can absorb light and thus limit photosynthetic growth of algal cultures proportionally to test substance concentration. Consequently, the experimental system in this study was modified (i.e. increased light intensity, shortened light path, reduced inoculation density, and constant shaking) in order to compensate for the physical effect of color. These modifications are recommended in OECD 23, however the physical effect of color may not be completely eliminated. In addition, effects of complexing substances in algal growth inhibition tests are mainly caused by chelation of essential cations, which leads to growth limiting reductions in the concentration of uncomplexed physiologically active ions. Inhibition of algal growth by complexing agents is therefore a secondary effect, which cannot be attributed to substance specific inherent toxic properties. Mitigating modifications, such as by compensating the deficit in the concentration of the essential ion(s), were not applied. Therefore and since a suitable Lemna minor toxicity test performed according to OECD guideline 221 showed no effects throughout the expsoure time of 7 days, the 72h-NOEC value of 8.1 mg/L was not further considered for the derivation of a PNEC for an environmental risk assessment.