Reaction mass of 2-[[4-[[3,5-dimethyl-4-(oxiran-2-ylmethoxy)phenyl]methyl]-2,6-dimethyl-phenoxy]methyl]oxirane and 1,3-bis[4-[[3,5-dimethyl-4-(oxiran-2-ylmethoxy)phenyl]methyl]-2,6-dimethyl-phenoxy]propan-2-ol and 1-[4-[[3,5-dimethyl-4-(oxiran-2-ylmethoxy)phenyl]methyl]-2,6-dimethyl-phenoxy]-3-[4-[[4-[3-[4-[[3,5-dimethyl-4-(oxiran-2-ylmethoxy)phenyl]methyl]-2,6-dimethyl-phenoxy]-2-hydroxy-propoxy]-3,5-dimethyl-phenyl]methyl]-2,6-dimethyl-phenoxy]propan-2-ol

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: EPA-821-R-02-013

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

The test substance was added without a carrier solvent to dilution medium at the highest treatment level. This was then stirred for up to 2 hours, and the remaining concentrations prepared by serial dilution (test solutions decanted to remove excess solution). The reported solubility of the test substance was incorrectly stated as 46.13 mg/L. A reliable water solubility test has shown this to be much lower (1.26 mg/L).

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchnerella subcapitata
- Source (laboratory, culture collection): Cultured at the testing laboratory.
- Age of inoculum (at test initiation): 4 days.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

Compliant with EPA conditions (13.6, not units detailed)

Test temperature:

24 +/- 2°C (continuous light; 4000 Lux)

pH:

Control values as 7.48 and 9.00 at 0 and 96 hours respectively.

Dissolved oxygen:

Control values as 7.9 - 8.4 (no units detailed) at 0 and 96 hours respectively.

Nominal and measured concentrations:

Nominal: Control, 3.3125, 6.625, 11.25, 22.5, 45 and 120 mg/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL BOD bottle
- Initial cells density: 10,000 cells/mL
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

OTHER TEST CONDITIONS
- Photoperiod: Continuous
- Light intensity and quality: 4000 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Other: Light absorbance

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.06, 0.6, 6.0, 60 mg/l
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Key result

Duration:

96 h

Dose descriptor:

other: IC25

Effect conc.:

> 45 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: determined by light absorbance

Validity criteria fulfilled:

yes

Conclusions:

In a 96 hr acute toxicity study, the 96hr IC25 value was determined >45 mg/L

Description of key information

In a 96 hr acute toxicity study, green algae (Pseudokirchneriella subcapitata) were exposed to the test substance at nominal concentrations of 0 (control), 2.83, 5.67, 11.25, 22.5, 45.0 and 120 mg/L under static conditions (nominal concentrations). 

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

45 mg/L

Additional information

Due to the low solubility of the test substance in the test medium, concentration levels that might be toxic for algae could not be reached (concentrations in any case tested above limit of aqueous solubility and no growth inhibition observed except at 120 mg/l). The 96hr IC25 was therefore above the solubility limit of the test substance in test medium.

The NOEC value was observed to be 45 mg/L based on the conditions in the test.