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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 Mar - 17 Mar 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

For the read-across justification see section 13.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Specific details on test material used for the study:

- Melting point: 63 °C
- Boiling point: 351 °C
- Water solubility: 0.82 mg/L (at 25 °C)
- log Pow: 5.64

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 10 mg/L (nominal concentration)
- Sampling method: same volume of test water was sampled by each test vessel and mixed in each group at the test initiation and after exposure.
- Sample storage conditions before analysis: analysis was conducted immediately after sampling, no storage

Vehicle:

yes

Remarks:

castor oil (HCO-50)

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: a stock solution (100 mg/L) was prepared with test substance, growth medium and dispersant. Stock solution was diluted with filter sterilized growth medium up to the concentration, and then filter sterilized.
- Controls: dilution water with/without vehicle
- Concentration of vehicle in test medium: stock solution: 1000 mg/L, final test solution: 100 mg/L
- Evidence of undissolved material: test water was colurless and no precipitate was observed.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: ATCC-22662
- Source: American Type Culture Collection
- Age of inoculum: < 3 days
- Method of cultivation: on a rotary shaker
- Initial cell density: 1x104 cells/mL

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions: same as test
- Any deformed or abnormal cells observed: not observed
- Temperature: 23+/-2ºC
- Light: 4000-5000 lux (continuous light)
- pH: no pH adjustments were made during exposure.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

23+/-2ºC

pH:

pH of the testing fluid at the start of exposure was 7.5-7.6; the pH at the end of the test was 8.4-9.1

Nominal and measured concentrations:

nominal concentration: 10.0 mg/L
measured concentration: 0 hour: 0.9 mg/L, 72 hour: < 0.8 mg/L (under detection limit)

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 mL Erlenmeyer flask capped with air-permeable stoppers
- Type: open
- Material, fill volume: glass, 100mL
- Initial cells density: 10000 cells/mL
- Control end cells density: 1884000 ± 59400 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuously
- Light intensity and quality: 4000 - 5000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter; 24, 48, 72 hours (measurements of the cell concentration were made by collecting 0.2 mL – 1.0 mL of the testing fluid from each test container, mixing it with electrolytes (Isotone II) so the total volume was 20mL, and measuring it with the Coulter Counter.)

TEST CONCENTRATIONS
- Justification for using less concentrations than requested by guideline: 10 mg/L is the highest concentration to be dissolved uniformly with solvent (100 mg/L)
- Range finding study: performed
- Test concentrations: 100 mg/L
- Results used to determine the conditions for the definitive study: EbC50: > 100 mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate (reagent grade)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EbC50: 0.52 mg/L (72 h)

Reported statistics and error estimates:

F & t-test

Table 1: Growth inhibition of Selenastrum capricornutum

Initial Measured Concentration (mg/L)	Biomass	Growth rate
	Inhibition (%)	Inhibition (%)
Control	-	-
Dispersant control	-0.05	-0.31
0.9	-3.36	-1.51

Validity criteria fulfilled:

yes

Conclusions:

It can be concluded that no toxic effects on aquatic algae for palmitic acid were observed up to the limit of water solubility.
Thus Reaction mass of stearic acid and stearic anhydride does not has to be classified.

Description of key information

It can be concluded that no toxic effects on aquatic algae for palmitic acid were observed up to the limit of water solubility.
Thus Reaction mass of stearic acid and stearic anhydride does not has to be classified.

The key values can be stated as:
EC50 > 0.9 mg/L
NOEC >= 0.9 mg/L