3-Methoxy-3-methylbutyl acetate

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:

23 August 2007 - 21 September 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to official OECD test guidelines, and in complaince with GLP; on this basis, the study may be considered reliable without restrictions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: OECD Guidance Document 23 "Guidance Document on Aquatic Toxicity Testing on Difficult Substances and Mixtures" (September 2000)

Deviations:

no

GLP compliance:

yes

Remarks:

The study report includes an statement of GLP complaince siigned by the study director, and a statement of quality assurance; however no GLP certificate issued by an independant body (such as an official GLP monitoring authority) is provided.

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 (control) and 100 mg/L.
- Sampling method: Sample taken from the preparation container at the start of the test. At the end of the test, samples were taken from each test vessel, combined, and an aliquot of the test solution removed for analysis following centrifugation.
- Sample storage conditions before analysis: Samples were analysed shortly after sampling; no storage was required.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
Test material was mixed with dilution water and stirred to prepare the test solution.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Old scientific name "Selenastrum capricornutum"
- Strain: ATCC 22662
- Source (laboratory, culture collection): American Type Culture Collection (Maryland, USA)

ACCLIMATION
- Acclimation period: 3 days under test conditions
- Culturing media and conditions (same as test or not): Yes

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

no data

Test temperature:

22.2 - 22.8°C.

pH:

7.7 - 7.8 at the start of exposure to 8.0 at the end of exposure.

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

Nominal concentration - 100 mg/L
Analysed concentrations = 98.7 mg/L (start of test) - 92.9 mg/L (end of test).

Details on test conditions:

TEST SYSTEM
- Test vessel: Sterilised 500 mL Erlenmeyer flask with gas-permeable silicon rubber plug.
- Initial cells density: 10^4 cells/mL.
- Control end cells density: Mean concentration = 9.83 x 10^5 (98.3 x 10^4) cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes - as described in the OECD test guideline.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: Continuous illumination.
- Light intensity and quality: 60 to 120 µE/m^2/s (not varying by more than ±15% of the mean).

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

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Not applicable - test conducted at the Limit concentration (100 mg/L) only.
- Justification for using less concentrations than requested by guideline: limit test conducted on the basis of a preliminary test.
- Range finding study
- Test concentrations: Preliminary test was conducted at the maximum concentration in the test guideline (OECD 201), 100 mg/L in duplicate analyses. As no growth inhibition was seen at this level, addtional levels were not assesed.
- Results used to determine the conditions for the definitive study: Yes; as no growth inhibition seen at 100 mg/L, the main test was conducted at this limit concentration.

Reference substance (positive control):

yes

Remarks:

An algae growth inhibition test of potassium dichromate (Reagent grade, Wako Pure Chemical Industries, Ltd.) with the test organisms was conducted to confirm the reproducibility of the test system (on July 23 - July 26, 2007).

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Based on result of statistical analysis of significant difference.

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): Yes - no abnormalities seen in control vessels at end of test; 100 mg/L level was consistent with control.
- Any stimulation of growth found in any treatment: No - no significant difference in growth rates between control and treatment level.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No signs of precipitation of the test material.
- Effect concentrations exceeding solubility of substance in test medium: No.

Results with reference substance (positive control):

The ErC50 (0-3d) of potassium dichromate was 1.04 mgIL. This value was within the normal range of the reference item in this laboratory (mean ± 2S.D.: 0.735 to 1.05 mgIL) [mean ± S.D.: 0.893 ±0.079 mgIL (n=4)].

Validity criteria fulfilled:

yes

Conclusions:

The ErC50 for the test material was determined to be greater than 100 mg/L. As no growth inhibition was seen in the 100 mg/L level when compared with the control, 100 mg/L was also the NOEC.

Description of key information

72-hour ErC50 for Pseudokirchneriella subcapitata is greater than 100 mg/L.  NOEC equal to or greater than 100 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L

Additional information

An algal growth inhibition study was conducted to determine the effect of the test material on aquatic plants. The study was conducted in accordance with OECD test guideline 201, and in compliance with GLP.

The growth of the algae Pseudokirchneriella subcapitata in untreated aquatic growth medium over a 72 hour test period was compared to the growth of algae in medium containing the test material at a concentration of 100 mg/L. The test was conducted in six replicate vessels at each concentration.

No difference in growth rates was seen between the control group and 100 mg/L group. On this basis, the 72 hour EC50 based on growth rate (E_rC₅₀) was determined to be greater than 100 mg/L. The NOEC was 100 mg/L.