2,6-bis(1,1-dimethylethyl)-4-(phenylenemethylene)cyclohexa-2,5-dien-1-one

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:

1999-05-26 to 1999-08-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP guideline study according to OECD 201 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 according to the current guideline adapted 2006.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

adopted on 7th June 1984

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

429-460-4

EC Name:

-

Cas Number:

7078-98-0

Molecular formula:

C21 H26 O

IUPAC Name:

2,6-bis(1,1-dimethylethyl)-4-(phenylenemethylene)cyclohexa-2,5-dien-1-one

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Since the test item has very low solubility, especially the main component, the recommendations of the Guidance Document for testing difficult substances (Department of the Environment, 1996) and OECD guideline (1992) were followed. A limit test was conducted at 100 milligrams per liter (mg wm/L). The test solution was prepared by weighing out the appropriate amount of test item (0.4018 grams), directly adding this to 4-Liters of freshwater algal media and stirring for 48-hours before being filtered through a 0.2 µm SuporCap™ filter from Gelman Sciences to remove undissolved material.

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Selenastrum capricornutum
- Source: Carolina Biological Supply Company (Burlington, NC)
- Age of inoculum: inoculum culture was 6 days old at test initiation

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

23.8 to 24.5°C

pH:

at the start of the test: 7.1 to 7.4
at the end of the test: 7.7 to 8.5

Nominal and measured concentrations:

100 mg/L nominal concentration

Details on test conditions:

TEST SYSTEM
- Test vessel: 100-mL of the chemical solution was transferred to sterile 250-mL glass Erienmeyer flasks.
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- Initial cells density: 10000 cells/L
- No. of vessels per concentration (replicates): three replicates
- No. of vessels per control (replicates): six replicates

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- in accordance to the guideline

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: 56-112 µE/m²/s

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Algal growth was measured by direct cell count using a 0.1mm deep hemocytometer (Reichert, Buffalo, NY) under a compound microscope. Counts were conducted on day ine and every 24 hours thereafter.
- other: Morphological observations were also conducted on the test treatment using a compound microscope to detect abnormal cell morphology and coloration as compared to the control.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

biomass

Remarks on result:

other: No acute toxic effects within the range of solubility

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

growth rate

Remarks on result:

other: No acute toxic effects within the range of solubility

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

growth rate

Remarks on result:

other: No acute toxic effects within the range of solubility

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

biomass

Remarks on result:

other: No acute toxic effects within the range of solubility

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): Observations of cell morphology detected no changes in test item exposed cells as compared to cells in control media.

Reported statistics and error estimates:

EC50 values were to be calculated based on both biomass and growth, EbC50, (comparison of areas under the growth curves and cell count) and on growth rates, ErC50. EC50 values and their 95 percent confidence limits were to be estimated by a computer program (U.S. EPA, 1994) for calculating EC50 values by probit analysis. In addition to the EC50 values, a no-observed-effect concentration (NOEC) was calculated by analysis of variance (ANOVA) with statistical differences between cell density means determined by Dunnett's procedure (U.S.EPA, 1988). Statistical differences were determined at a probability level of 0.05.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

With high probability acutely not harmful to aquatic algae.