Alcohols, C11-15-secondary, ethoxylated

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:

other: Study conducted to internationally accepted guidelines and to GLP.

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)

Analytical monitoring:

no

Vehicle:

yes

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata,
- Strain: CCAP 278/4.
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd., Dunstaffnage Marine Laboratory, Dunbeg, Oban, Argyll, Scotland
- Age of inoculum (at test initiation):
- Method of cultivation:

ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

See table 1 below in any other information for temperature measurements.

pH:

See table 1 below in any other information for pH measurements.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL conical flasks
- Type (delete if not applicable): loosely plugged with foam bung
- Material, size, headspace, fill volume:
- Aeration:
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- Initial cells density: 1.1 x 10E4/mL.
- Control end cells density:
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 2 at 0.0954 mg/L test substance, 3 at all other concentrations
- No. of vessels per control (replicates):
- No. of vessels per vehicle control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
- Total organic carbon:
- Particulate matter:
- Metals:
- Pesticides:
- Chlorine:
- Alkalinity:
- Ca/mg ratio:
- Conductivity:
- Culture medium different from test medium:
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: yes
- Photoperiod: Continuous
- Light intensity and quality: 4440 to 8880 lux provided by 6 x 30 W “cool white” 1 metre fluorescent tubes
- Salinity (for marine algae):

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter
- Chlorophyll measurement:
- Other:

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.3 approx.
- Justification for using less concentrations than requested by guideline:
- Range finding study 0.1, 1 and 10 mg/L
- Test concentrations: 0.0954, 0.305, 0.977, 3.13 and 10 mg/L as water accommodated fractions
- Results used to determine the conditions for the definitive study: After 72 hours, algal growth was inhibited by 44% and 98% at 1 and 10 mg/L respectively; no significant inhibition occurred at 0.1 mg/L

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

1.03 mg/L

Remarks on result:

other: 95% CL 1.01 - 1.33 mg/L

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

2.01 mg/L

Basis for effect:

growth rate

Remarks on result:

other: 95%CL 1.88 - 2.16 mg/L

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

0.305 mg/L

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

After 72 hours of exposure to Softanol 30, the EbL50, ErL50 and EyL50 respectively, were 1.03, 2.01 and 1.05 mg/L.
The “no observed effect loading rate” (NOELR) for area under the growth curve, growth rate and yield for Softanol 30 was 0.305 mg/L.

Description of key information

One study is available and valid.
The effect of Softanol 30 on the growth of green algae (Pseudokirchneriella subcapitata) was studied under mixed population conditions (Huntingdon Life Sciences Ltd, 2010 report PLZ0024). Triplicate algal cultures, with an initial cell density of 1 x 104/mL, were exposed to water accommodated fractions (WAFs) of Softanol 30 prepared from aqueous mixtures with initial nominal concentrations (loading rates) of 0.977, 3.13 and 10 mg/L.
The 72-hour ErL50of algae exposed to the test substance was determined to be 2.01 mg/L.
This study is classified as acceptable and satisfies the guideline requirements for a growth inhibition study with aquatic plants.

Key value for chemical safety assessment

EC50 for freshwater algae:

2.01 mg/L