Isooctyl acetate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 July 1985 - 26 July 1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Analytical verification not fully reliable.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1985

Report date:

1985

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

-Effect concentration based on % water soluble fraction (WSF)

GLP compliance:

yes

Remarks:

EPA Good Laboratory Practice Regulations set forth in 40 CFR Part 792

Test material

Test material information

Constituent 1

Reference substance name:

Isooctyl acetate

EC Number:

250-701-2

EC Name:

Isooctyl acetate

Cas Number:

31565-19-2

Molecular formula:

C10H20O2

IUPAC Name:

Acetic acid, isooctyl ester

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Batch II

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: The stability, identity, strength, and composition or other characteristics which appropriately identify the test substance are the responsibility of the Sponsor.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Control, 6.25, 12.5, 25, 50 and 100 %
- Sampling method: Samples for test material concentration verification were taken from all test treatments on Day 0 prior to adding organisms and at study termination and at study termination. All samples were analyzed by the Total Carbon method.
- Sample storage conditions before analysis: Samples were not stored.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The MRD-83-303 water soluble fraction was prepared by combining 6.7 ml of test material with 1 liter of AAP nutrient media in a 2 liter flask. This mixture was slowly stirred for approximately 72 hours. After the mixing period, the mixture was transferred into a separatory funnel and allowed to settle for approximately 1 hour. After the settling period, the water soluble fraction was drawn off and used as the 100% stock solution.

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Selenastrum capricornutum
- Strain: strain (1648)
- Source (laboratory, culture collection): Cultured in the Environmental Laboratory. Initial strain (1648) provided by Department of Botany, University of Texas.
- Age of inoculum (at test initiation): The study was started with algal cells in the log phase of growth as calculated from growth of stock cultures.
- Method of cultivation: The algae are cultured in AAP(l) nutrient media prepared with distilled water and reagent grade chemicals. The media was prepared as per standard laboratory procedures. Culture vessels were sterile glass flasks whose volume was approximately 60% of capacity. The cultures were maintained in 400 (+/- 10%) footcandles of continuous cool white light, on a stirring platform with aeration, at a continuous temperature of 21 (+/- 1) degrees C. Stock cultures were maintained for approximately 14 days with new stock prepared weekly. Additional culture information is available in the Algal Culture Log at EHSL.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test conditions

Test temperature:

23.99 +/- 0.06°C

pH:

7.5 (+/- 0.1)

Nominal and measured concentrations:

Nominal: Control, 6.25, 12.5, 25, 50 and 100 % WSF
Measured: Control, 2.78, 5.74, 10.31, 21.46 and 44.71 (as ppm total carbon; NOTE: MEASURED VALUES = TOTAL CARBON ATTRIBUTABLE TO THE TEST MATERIAL ON DAY 0)

Details on test conditions:

TEST SYSTEM
- Test vessel: sterile glass flasks
- Material, size, headspace, fill volume: material: glass, size: 125 mL, headspace: yes, fill volume: 50 mL
- Initial cells density: 2 x 10^4 cells/ml
- Control end cells density: 4.6 x 10^6 cells/mL
- No. of vessels per concentration (replicates): 3 replicates
- No. of vessels per control (replicates): 3 replicates

GROWTH MEDIUM
- Standard medium used: yes, AAP nutrient media (Miller, et al., 1978. The Selenastrum capricornutum Printz Algal Assay Bottle Test. U.S. EPA pp.17-18.)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: distilled water
- Culture medium different from test medium: The acute algal study was performed by combining fresh media and test material stock solution.

OTHER TEST CONDITIONS
- Adjustment of pH: The pH was adjusted to 7.5 (+/- 0.1) prior to adding test organisms.
- Photoperiod: 24 h
- Light intensity and quality: intensity: 400 footcandles.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Chlorophyll measurement: Chlorophyll-a fluorescence readings

TEST CONCENTRATIONS
- Range finding study: yes
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

ca. 99.07 other: % WSF

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence interval: 73.67 - 167.77

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values:

Reported statistics and error estimates:

A computer program was written to perform the Algal EC50 calculations described in New Environmental Effects Test Guidelines EPA 560/6-83-002. Both the Specific Maximum Growth Rate and Mean Relative Growth Rate methods were performed.
These results are corroborated by the specific maximum growth rate method which indicate a mean inhibition at the 100% WSF treatment of 55.5 percent.

Any other information on results incl. tables

Table 1: Mean Cell Concentrations (cells/mL)

Date	Control	6.25	12.5	25.0	50.0	100.0
22-JUL-85	2.2 x 10^4	2.1 x 10^4	2.0 x 10^4	2.0 x 10^4	2.0 x 10^4	2.0 x 10^4
23-JUL-85	9.3 x 10^4	9.3 x 10^4	8.1 x 10^4	8.8 x 10^4	5.5 x 10^4	3.1 x 10^4
24-JUL-85	5.9 x 10^5	5.5 x 10^5	4.3 x 10^5	5.4 x 10^5	2.5 x 10^5	7.0 x 10^4
25-JUL-85	2.6 x 10^6	2.5 x 10^6	1.7 x 10^6	2.1 x 10^6	1.0 x 10^6	1.1 x 10^5
26-JUL-85	4.6 x 10^6	4.0 x 10^6	2.7 x 10^6	3.6 x 10^6	2.5 x 10^6	1.8 x 10^5

 

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

A 96-h ErC50 was calculated at 99.07 (%WSF) for Pseudokirchneriella subcapitata based on the nominal values of the test material. Based on the 96-h ErC50, the test material is not classified as acutely toxic to freshwater algae according to Regulation (EC) No. 1272/2008 (CLP).