Fatty acids, C10-12, esters with polylactic acid, 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:

14 August 2012- 17 August 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study was performed according to GLP requirements. Chemial analysis was performed at a laboratory approved by the Swedish Medical Products Agency to be in compliance with Good Manufacturing Practice according to GMP guidelines laid down in Directive 2003/94/EC.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 2.0, 5.0, 10, 20 and 45 mg/L
- Sampling method: at t(0), t(24h), t(48h) and at termination of the test samples of approximately 45 ml were collected
- Sample storage conditions before analysis: Samples were stored in 50 ml glass bottles and stored at - 20°C +/- 2°C

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
Stock Solution:
Stock solution was prepared by adding 50.0 mg/L by weighing out 100 mg of the test product and dissolving it in 2,000 mL of algal test medium. pH was adjusted from 7.0 to 8.0 by adding 8 droplets of 1 M NaOH.
Test solutions:
The test solutions were prepared by diluting the stock solution in the algal test medium.
Controls: yes (0; blank)

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriela subcapitata
- Strain:clone: NIVA, CHL 1)
- Source (laboratory, culture collection): NIVA, Norway; The alga is cultured at DHI under test conditions prior to the test.
- Age of inoculum (at test initiation): Test was started when cell density was approx. 9,000 cells/mL

ACCLIMATION
- Acclimation period: The alga were incubated for approx. 72 hours under continuous shaking (approx. 120 RPM) at a temperature of 23.1°C+/- 0.1°C and constant illumination from a panel of fluorescent light with an intensity of approx. 60-120 µmol x m-2 x sec-1.
- Culturing media and conditions: Freshly produced ISO- medium was used as growth medium in the test. Medium was prepared from Millipore water , and salts were added according to the standard procedure.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

n.a.

Hardness:

n.a.

Test temperature:

23 °C +/- 2°C

pH:

Start: 7.9
End: 8.8 +/- 0.6 at the end of the test
Control:
Start: 7.9
End: 9.1

Dissolved oxygen:

n.a.

Salinity:

n.a.

Nominal and measured concentrations:

Nominal concentrations: 0, 1.0, 2.0, 5.0, 10, 20, 45 mg/L
Measured concentrations: 2.0, 3.1, 5.8, 14.8, 22.8 mg/L. These results are mean results from time - weighted measured test concentrations. No sample was taken from the control and test concentration 1.0 mg/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: conical glass flasks with wide neck
- Material, size, headspace, fill volume: total capacity: 250 ml, fill volume: 100 ml/flask
- Initial cells density: approx. 9,000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6 (algae but without test substance) + 1 per each concentration (test substance but no algae)

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Millipore
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Photoperiod: constant
- Light intensity and quality: Panel of fluorescent light with an intensity of approx. 60-120 mmol x m-2 x sec-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Cell growth was followed as in-vivo fluorescence in triplicate test flasks, the blanks and the six controls by use of a Turner TD-700 Laboratory Fluorometer.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: 2.0

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

6 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

dissolved

Basis for effect:

growth rate

Remarks on result:

other: 3.5-8.1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 22.8 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

dissolved

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 2.0

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

9.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 5.9-12.6

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 45 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values:
At pH values higher than pH 7 hydrolysis of lactylic esters may occur. This property led to a decrease of test substance in the medium within exposure period.

Results with reference substance (positive control):

- Results with reference substance valid? yes. Value was not significantly different from the result obtained in an international ring test (1981)
- EC50 : 1.10 (1.03-1.18) mg/L

Reported statistics and error estimates:

Growth and growth inhibition were calculated for each test concentration relative to the control without addition of the product. Growth rate and yield were caluclated by using the computer program TOXEDO. The NOEC values were determined by use of computer program Dunnett`s procedure as the highest tested concentration, at which no significant inhibition is observed.
The concentrations of potassium dichromate inhibiting the growth rate were calculated by use of TOXEDO program and expressed as EC10 and EC 50 according to ISO standard.

Table 1: Validity criteria for OECD 201.

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	Control growth rate exceeded 1.4 per day
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%	5.8	yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	1.4%	yes

 

Validity criteria fulfilled:

yes

Remarks:

Please refer to "Any other information on results incl. tables"

Conclusions:

Dermosoft decalact caused significant inhibition of the growth of Pseudokirchneriella subcapitata at nominal concentrations of 5-45 mg/L. NOEC for the growth rate was 2.0 mg/L, EC 10 was 9.5 mg/L and EC 50 was > 45 mg/L based on nominal concentrations.

Executive summary:

Dermosoft decalact was tested for inhibitory effects on the growth of the micro alga Pseudokirchneriella subcapitata according to OECD guideline 201.

No significant effect was observed on the growth of Pseudokirchneriella subcapitata at concentrations up to 2.0 mg/L. Significant inhibition of the growth of Pseudokirchneriella subcapitata was observed at nominal concentrations of 5.0 - 45 mg/L.

Description of key information

EC50 (72 h): > 22 mg/L (meas. arithm. mean)
EC10 (72 h): 6 mg/L (meas. arithm. mean); NOEC (72 h): 2 mg/L (meas. arithm. mean);

Key value for chemical safety assessment

EC50 for freshwater algae:

22 mg/L

EC10 or NOEC for freshwater algae:

6 mg/L

Additional information

The toxicity to aquatic algae was investigated in a study conducted according to OECD guideline 201. Green algae of the species Pseudokirchneriella subcapitata were exposed to nominal test substance concentrations of 1.0 2.0, 5.0, 10, 20 and 45 mg/L. An analytical dose verification using HPLC was performed. Samples for analysis were taken at 0 h, 24 h, 48 h and at test termination after 72 h. A decline of in the test concentrations was observed between 24 and 48 hours. The time-weighted measured test concentrations were 2.0, 3.1, 5.8, 14.8 and 22.8 mg/L. The determined EC50 (72h) was > 22 mg/L (time weighted meas.). The EC50 (72 h) was 6 mg/L (time-weighted meas., NOEC (72 h): 2 mg/L).