4,4',4''-(ethan-1,1,1-triyl)triphenol

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)

Deviations:

no

Remarks:

Conducted according to guideline in effect at the time of study conduct

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Nominal concentrations: 0.18, 0.39, 0.84, 1.8, 3.9, 8.4, and 18 mg/L
- Sampling method: Water samples (~100 mg in duplicate) were taken from control and test cultures at 0 hours and at 72 hours (replicated pooled).
- Sample storage conditions before analysis: For each pair of duplicate samples, one sample was analyzed (storage not reported) and the other was stored at 4ºC in case a check analysis was required.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test substance was stirred overnight in sterile nutrient medium at 30°C and cooled to 24°C to given an initial stock solution of 20 mg/L. Aliquots of this stock solution were used to produce the final series of exposure levels.
- Controls: triplicate vessels were prepared for the control and each exposure level. An additional exposure level was prepared at the highest test concentration but without algal cells present.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): Not reported

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Green alga
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Center of Algae & Protozoa c/o Freshwater Biological Association, Cumbria, U.K.
- Age of inoculum (at test initiation): Not reported
- Method of cultivation: Sterile nutirent medium was inoculated from a master culture and incubated under continuous illumination (~7000 lux) and stirring (orbital shaker) at 23 ± 2°C to give an algal suspension in log phase growth characterised by an absorbance of 0.200 (@ 665 nm).

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

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

No

Hardness:

Not reported

Test temperature:

24 ± 1°C

pH:

8.2-8.8

Dissolved oxygen:

Not reported

Salinity:

Not reported

Nominal and measured concentrations:

Nominal concentrations: 0, 0.18, 0.39, 0.84, 1.8, 3.9, 8.4, and 18 mg/L
Measured concentrations (mean of 0 and 72 hr analyses): 0, 0.23, 0.36, 0.77, 1.6, 3.8, 7.5, and 16 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml conical flask
- Initial cells density: 7.9x10E4 cells/mL
- Control end cells density: 1.3x10E6 cells/mL
- No. of organisms per vessel: Not reported
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes; as recommended in Official Journal No. L383A Part C.3

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous illumination for 72 hours
- Light intensity and quality: 7000 lux provided by 7 X 30 W "universal white" 1 metre fluorescent tubes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: spectrophotometer
- Microscopic inspection of test and control cultures: 72 hours

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

other: ErC50

Effect conc.:

8.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence limits 6.3-12 mg/L

Duration:

72 h

Dose descriptor:

other: EbC50

Effect conc.:

3.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence limits 1.8-7.0 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.23 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): At the highest test level (16 mg/L) the cells appeared smaller compared to the control.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: none

Validity criteria fulfilled:

yes

Conclusions:

72-hour EbC50 = 3.6 mg/L
72-hour ErC50 = 8.6 mg/L
72-hour NOEC = 0.23 mg/L

Executive summary:

A study was performed to assess the inhibitory effect of the test substance on the growth of the unicellular green alga Selenastrum capricornutum, Strain No. CCAP 278/4. The study was conducted in accordance with EEC Methods for Determination of Ecotoxicity Annex to Directive 92/69/EEC Part C, Method 3 "Algal Inhibition Test" and the OECD Guideline for Testing of Chemicals No. 201 "Alga, Growth Inhibition Test". Algal cultures exposed to seven test concentrations of test substance plus one untreated control, each in triplicate, were incubated on an orbital shaker under continuous illumination at 24 ±1°C for 72 hours. Growth was monitored daily by measuring the absorbance of each culture at 665 nm.

The following values were derived from the data:

E_bC₅₀ (72 h): 3.6 mg/L

E_rC₅₀ (0 -72 h): 8.6 mg/L

"No-observed effect level": 0.23 mg/L

Description of key information

72-hour ErC50: 8.6 mg/L
72-hour NOEC: 0.23 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

8.6 mg/L

EC10 or NOEC for freshwater algae:

0.23 mg/L