2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol

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:

1992-06-15 to 1992-06-18

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Non-GLP guideline study. Deviations to the updated OECD Guideline (adopted 2006): The coefficient of analysis of the daily growth rate in the control replicates and the coefficient of analysis of the average specific growth rates in the control replicates were not reported. No analytical confirmation.

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stock solution: 2.0 g test substance were mixed with 18 g of a 0.4% alkylphenol-polyglycol-ether solution in water. 1 ml of this blend were mixed and made up to 1000 ml with water, achieving a concentration of 100 mg/L.
- Controls: water, vehicle
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): alkylphenol-polyglycolether
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): 3.6 mg/L
- Evidence of undissolved material (e.g. precipitate, surface film, etc): none

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green Algae
- Source (laboratory, culture collection): Ciba-Geigy Ltd., testing facility
- Method of cultivation: according to the guideline

ACCLIMATION
- Preculture: 3 d under test conditions

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 +/- 1 °C

pH:

control: 7.7 - 9.5
vehicle: 7.7 - 9.5
Test concentrations: 7.8 - 10.0

Nominal and measured concentrations:

1.23, 3.7, 11, 33, 100 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml Erlenmeyer flasks, stoppered with aluminium caps, on Lab-shaker
- Type (delete if not applicable): closed
- Fill volume: 50 ml test solution per flasks
- Initial cells density: 9700 cells/ml
- Cell density after 72 h exposure: min. 202.0 cells/mL*10000
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Composition according to the guideline
- Intervals of water quality measurement: Temperature was continuously measured and maintained at 23 ± 1°C. pH was measured at 0h and 72h exposure

OTHER TEST CONDITIONS
- Lighting: Continuous illumination, cold white fluorescent light, 130 µE/m2 sec +- 20 % (approx. 8000 lux)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Cell densities were measured at 24, 48 and 72 hours exposure on a "TOA" cell counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.0
- Test concentrations: 1.23, 3.7, 11, 33, 100 mg/L

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

other: EbC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

other: NOEbC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Exponential growth in the vehicle control (for algal test): yes
- Observation of abnormalities (for algal test): none
- Any stimulation of growth found in any treatment: promotion of algal growth compared to control in the vehicle
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: none
- Effect concentrations exceeding solubility of substance in test medium: yes

Description of key information

With high probability acutely not harmful to aquatic algae. 

Additional information

The toxicity to algae was assessed in an Algal growth inhibition test in accordance OECD guideline 201. Algae were exposed to test item at nominal concentrations of 1.23, 3.7, 11, 33, and 100 mg/L. The EbC50 was determined to be > 100 mg/L the NOEC was determined to be 100 mg/L.