2-[(2-ethylhexyl)oxy]ethanol

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:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: TXEG
- Expiration date of the lot/batch: December 13, 2017
- Purity test date: December 13, 2016

RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity:
- Specific activity:
- Locations of the label:
- Expiration date of radiochemical substance:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: 20 +/- 5 degrees Celsius in the dark
- Stability under test conditions:
- Solubility and stability of the test substance in the solvent/vehicle:
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium:

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing:
- Preliminary purification step (if any):
- Final dilution of a dissolved solid, stock liquid or gel:
- Final preparation of a solid:

FORM AS APPLIED IN THE TEST (if different from that of starting material)

TYPE OF BIOCIDE/PESTICIDE FORMULATION (if applicable)

OTHER SPECIFICS:

Analytical monitoring:

yes

Details on sampling:

The samples were taken from the biological phase of the study. Collecting, storage and handling over of the samples were the Study Director’s responsibility. The information concerning the samples was provided by the Study Director. One sample from the freshly prepared stock solution and duplicate samples from the freshly prepared test media (containing algae) of all test concentrations and from the control were taken at the start of the test. For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, duplicate samples from the test media of all test concentrations and the control (containing algae) were taken at the end of the test (after the 72 hours test period) by pooling the contents of the test beakers of each treatment. The samples were diluted by a factor of five with methanol. One additional sample of the untreated control and of the dilution solvent was taken at test start and test end without any sample treatment.

Vehicle:

no

Details on test solutions:

The test was started (0 hours) by inoculation of a biomass of approx. 5000 algal cells per mL test medium. These cells were taken from an exponentially growing pre-culture, which was set up 4 days prior to the test start under the same conditions as in the test. The test was performed with three replicates per test concentration and six replicates in the control. Volumes of 50 mL of algal suspension per replicate were continuously stirred with magnetic stirrers in 50 mL Erlenmeyer flasks. The flasks were covered with glass dishes and incubated in a water bath. The flasks were placed in a random order and were repositioned each day to minimize differences in test conditions. Additionally, one replicate of each test concentration and of the control was prepared without algae to provide a "blank" for the spectrophotometric measurements. The additional replicates were incubated under the same conditions as described above. The blank values were subtracted from the absorption measured in the samples containing algae in order to eliminate absorption caused by the test item (see also "Determination of the Cell Density").

Test organisms (species):

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

Details on test organisms:

Pseudokirchneriella subcapitata (KORSHIKOV), Strain No. 61.81 SAG, formerly known as Selenastrum capricornutum, and recently renamed as Raphidocelis subcapitata (KORSHIKOV). The algae were supplied by the „Sammlung von Algenkulturen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Universität Göttingen", 37073 Göttingen, Germany. The algae were cultivated in the laboratories of ibacon under standardised conditions according to the test guidelines.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

0.24 mmol/L = 24 mg/L

Test temperature:

20.0 to 22.9 degrees Celsius

pH:

8.0 to 8.1 at test initiation and 8.2 to 9.8 at test termination

Dissolved oxygen:

not applicable

Salinity:

not applicable

Nominal and measured concentrations:

nominal 80, 25.3, 8.0, 2.5, 0.8, 0.25 and 0.08 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer Flask
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 50 mL
- Aeration: none
- Type of flow-through (e.g. peristaltic or proportional diluter): static
- Renewal rate of test solution (frequency/flow rate):
- Initial cells density: 5000 algal cells per mL test medium
- Control end cells density:
- No. of organisms per vessel:
- No. of vessels per concentration (replicates):
- No. of vessels per control (replicates):
- No. of vessels per vehicle control (replicates):

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/no
- Adjustment of pH:
- Photoperiod:
- Light intensity and quality:
- Salinity (for marine algae):

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]
- Chlorophyll measurement:
- Other:

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

36 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

72.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

25.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Reported statistics and error estimates:

Based on the calculated cell densities, the 72 hours ErC50 and the 72 hours EyC50 (see Definitions), the corresponding EC20 and EC10 values and where possible their 95 %-confidence limits were calculated by Probit analysis. For the determination of the 72 hours LOEC and the 72 hours NOEC, the calculated growth rates and yields at each test concentration were tested for significant differences compared to the control values by Dunett’s t-test (yield and growth rate). The software used to perform the statistical analysis was ToxRat Professional, Version 3.2.1, ToxRat Solutions GmbH.

Validity criteria fulfilled:

yes

Conclusions:

The influence of Eastman (TM) EEH Solvent on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static concentration-response test. The 72-hour EyC50 was calculated to be 36.0 mg test item/L, and the 72-hour ErC50 value was calculated to be 72.9 mg test item/L. The 72-hour NOEyC was determined to be 8.0 mg test item/L and the associated 72-hour LOEyC was 25.3 mg test item/L. The 72-hour NOErC was determined to be 25.3 mg test item/L and the associated 72-hour LOErC was 80 mg test item/L.

Executive summary:

The influence of Eastman (TM) EEH Solvent on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static concentration-response test. The 72-hour EyC50 was calculated to be 36.0 mg test item/L, and the 72-hour ErC50 value was calculated to be 72.9 mg test item/L. The 72-hour NOEyC was determined to be 8.0 mg test item/L and the associated 72-hour LOEyC was 25.3 mg test item/L. The 72-hour NOErC was determined to be 25.3 mg test item/L and the associated 72-hour LOErC was 80 mg test item/L. The quantification of the test item Eastman (TM) EEH Solvent in the test samples was performed using gas chromatography with flame ionization detection. At the start of the test 108% of the nominal test concentrations were found (average of the nominal concentrations of 80, 25.3 and 8 mg test item/L). After 72 hours test duration, 105% of the nominal value was determined (average of the nominal concentrations of 80, 25.3 and 8 mg test item/L). During the test the algae were exposed to a mean of 107% of nominal (average of the nominal concentrations of 80, 25.3 and 8 mg test item/L. The nominal concentrations of 2.5, 0.8, 0.25 and 0.08 mg test item/L were below the Limit of Quantification (LOQ). As these concentrations were below the 72-hour NOEC for yield and growth rate (see Table 1), dose verification was not required according to the study plan. Since the nominal concentrations of 80, 25 and 8 mg test item/L were within 100±20% recovery at test start and test end, all biological results were calculated based on nominal concentrations.

Description of key information

The influence of Eastman (TM) EEH Solvent on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static concentration-response test. The 72-hour EyC50 was calculated to be 36.0 mg test item/L, and the 72-hour ErC50 value was calculated to be 72.9 mg test item/L. The 72-hour NOEyC was determined to be 8.0 mg test item/L and the associated 72 -hour LOEyC was 25.3 mg test item/L. The 72-hour NOErC was determined to be 25.3 mg test item/L and the associated 72-hour LOErC was 80 mg test item/L. All test concentration were based on nominal concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:

72.9 mg/L

EC10 or NOEC for freshwater algae:

25.3 mg/L