Fatty acids, C8-18 and C18-unsatd., reaction products with diethanolamine and propylene oxide

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test solutions were prepared separately for each test concentration. The test solutions were prepared by adding test substance to 1L or 2L of test medium and stirring for approximately 1 hour. The test solutions appeared colorless and clear

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green alga
- Strain: SAG 61.81
- Source: 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 and propagated on a weekly basis. Before the exposure an inoculum culture is prepared from the stock culture and incubated for 4 days at 24 °C (max. temperature difference 2 °C). After this time, the inoculum culture is in exponential growth phase and can be used to initiate the test (study day 0).

CULTURE CONDITIONS
- Inoculum:
- An inoculum culture in exponential growth phase was prepared with an aliquot of the stock algal culture added to sterile test media to provide an initial cell density of 10000 cells/ml.
- Incubation under test conditions for 4 days prior to test initiation
- Inoculum culture cell density (4 days growth) : 217E+4 cells/ml
- Inoculum culture morphology: normal and healthy
- Culturing media and conditions: The culture and test medium (USEPA medium or AAP, also according to ASTM) was prepared according to OECD Guideline for Testing of Chemicals, No. 201

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

25 °C

pH:

Study initiation: 7.6
Study end: 7.8 - 9.8

Nominal and measured concentrations:

Nominal test concentrations: 0, 0.56, 1.0, 1.8, 3.2, 5.6, 10 mg/L
Mean measured concentrations: -, 0.25b, 0.3b, 0.9b, 1.5, 3.0, 6.5 mg/L
b: measured concentration below limit of quantification

Details on test conditions:

TEST SYSTEM
Inoculated replicates:
- Test vessels: Erlenmeyer flasks (nominal volume 250 mL) plugged with gas permeable silicone sponge caps
- Test volume: 100 mL
- Initial cell density: 1 x 104 cells/mL
- Replicates per test concentration: 3
- Replicates per test control: 3
*An additional replicate is prepared for 0h concentration control analysis only

Uninoculated replicate:
- Purpose: To correct for background fluorescence and for pH measurements. To determine the effect of the test system on test substance
stability.
- Test vessels: Erlenmeyer flasks (nominal volume 250 mL) plugged with gas permeable silicone sponge caps
- Test volume: 100 mL
- Replicates per test concentration/ control: 1
- Replicates per test control: 1

- Temperature measurement: Continuous measurement during the whole test period in the climate chamber in a flask with deionized water
- pH measurement: after 0 and 96 h

EFFECT PARAMETERS MEASURED:
- Algal growth measured as in vivo chlorophyll-a fluorescence (pulsed excitation with light flashes having a wavelength of 432 nm) after 96 h
- Determination of correlation between fluorescence and cell density:The fluorescence in the dilutions and the undiluted mixture were measured by single measurements and in parallel by direct microscopic cellcounting (two counts in a Neubauer haemocytometer).
- Algal morphology microscopically at the start of the test and at the end of the test (a pooled sample from each test concentration)

TEST CONCENTRATIONS
- Range finding study: yes
- Results used to determine the conditions for the definitive study (72 h): EC50 = 4.28 mg/L (fluorescence); ErC50 = 3.48 mg/L (nominal)

RECOVERY PHASE EVALUATION
- 0.5 mL aliquots of test solution from each replicate of the lowest concentration of test chemical which completely inhibited algal growth was used and combined these aliquots into a new test vessel
- Dilution 1:100 with fresh algal media to dilute the test substance to a concentration which does not affect growth (e.g. 1 mL inhibited algae + 99 mL fresh media)
- Incubation for a period of up to 9 days, and measurement of fluorescence every 2 days to check for algal growth.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

2.14 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

96 h

Dose descriptor:

EC10

Effect conc.:

1.46 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

1.47 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

96 h

Dose descriptor:

EC10

Effect conc.:

1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

96 h

Dose descriptor:

EC90

Effect conc.:

2.62 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

96 h

Dose descriptor:

EC90

Effect conc.:

3.45 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

1.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Algal morphology: no remarkable observation at a concentration of 0, 0.56, 1.0, 1.8 and 3.2 mg/L (nominal); at a concentration of 5.6 and 10 mg/L (nominal) no algal cells were observed
- Based on results of the recovery phase investigation, the altered growth response between controls and test algae is due to algistatic effects.

Results with reference substance (positive control):

ErC50 (72 h) = 1.36 mg/L
ErC50 (96 h) = 1.47 mg/L
Date of the last control experiment: 16 Feb 2009

Validity criteria fulfilled:

yes

Conclusions:

The substance is toxic to freshwater algae.

Description of key information

EC50 (96h) = 2.14 mg/L  and EC10 (96h) = 1.46 mg/L (measured) for Pseudokirchnerella subcapitata (OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:

2.14 mg/L

EC10 or NOEC for freshwater algae:

1.46 mg/L

Additional information

The toxicity on aquatic algae was investigated for Fatty acids, C8-18 and C18-unsatd., reaction products with diethanolamine and propylene oxide (CAS 1000817-22-0) in a GLP guideline study according to the OECD 201 (BASF 2009). The analytical monitored study was conducted with the green algae species Pseudokirchneriella subcapitata. After 96 hours of exposure the ErC50 is determined to be 2.14 mg/L and the ErC10 is determined to be 1.46 mg/L based on measured concentrations.