2,2,4-trimethylpentane-1,3-diol

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study conducted under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2,2,4-trimethylpentane-1,3-diol

EC Number:

205-619-1

EC Name:

2,2,4-trimethylpentane-1,3-diol

Cas Number:

144-19-4

Molecular formula:

C8H18O2

IUPAC Name:

2,2,4-trimethylpentane-1,3-diol

Details on test material:

- Name of test material (as cited in study report): 2,2,4-Trimethyl-1,3-pentanediol or TMPD
- Physical state: white solid
- Analytical purity: 99%
- Purity test date: 2000-11-6
- Lot/batch No.: 021500

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

The exposure concentration was based on the geometric mean of the analyzed solutions, averaged over the three replicates, at test start and at 24-hour intervals throughout the test.

Test solutions

Vehicle:

no

Details on test solutions:

One concentration of the test substance was prepared by mixing 72.1 mg of the test substance with 10 mL of algal growth media. The solution was then dissolved by sonication for approximately 5 minutes and transferred to a sterile, tared 1-L polystyrene flask. The total weight of the solution was adjusted to 655.5 g using algal growth media. The nominal concentration of the test substance in the algal media was 110 mg/L. The resulting test substance solution was then sterile-filtered through a 0.45 um cellulose nitrate membrane into a sterile 1-L Nalgene receiver flask. An aliquot (1.0 mL) of the test solution was removed for analysis by GC/FID at time 0.

Test organisms

Test organisms (species):

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

Details on test organisms:

The test alga, Selenastrum capricornutum SF-3148, was obtained from the American Type Culture Collection, Rockville, MD, and was subsequently cultured in the testing facility. A 4-day culture, passage 2 in liquid algal medium, was used as the source of test inoculum. Several previous passages were performed in order to confirm exponential growth under the conditions of the test.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

A mean temperature of 24°C was maintained.

pH:

The pH values for the test solutions and control solutions ranged from 7.4 at test start to 7.6 at test end.

Nominal and measured concentrations:

110 mg/L nominal
The geometric mean of the test substance in the exposure solutions was calculated as 110.1 mg/L.

Details on test conditions:

Sterile algal medium was prepared using high quality distilled water. The pH of the algal medium was adjusted to 7.5 ± 0.1 using NaOH prior to use. This medium was used to prepare the exposure solutions of the test substance as well as the controls. Sterile 250-mL Erlenmeyer flasks were
conditioned by adding 1-2 milliliters of the appropriate test solution, swirling to coat the flask, and then removing the solution by inverting into a waste beaker. A total of 8 flasks were prepared. Five flasks were conditioned for the test substance, of which three had algae, one served as the chemical control exposed to light, and one served as the chemical control protected from light. Three flasks were conditioned with algal medium and used as negative controls. All steps in the procedure were carried out aseptically in a hood to prevent biological contamination of the test and control solutions. Algae were inoculated into each flask containing the test substance solution and into the negative control flasks to give a cell concentration of 10e4 cells/mL. The flasks were secured with foam stoppers and then transferred to the incubator in random order where they were maintained at a temperature of approximately 24°C and shaken at approximately 100 rpm. A mean illumination of 724 ± 7.8 foot-candles was maintained. Flasks were rotated randomly at 24-hour intervals following cell counts. Cell concentrations were measured after 24, 48, and 72 hours of exposure. Flasks were swirled to achieve a uniform cell suspension and 4.0 mL were removed for counting. A Coulter Counter was used to perform cell counts. Prior to performing cell counts a sample was counted using a hemacytometer and the results used to calibrate the Coulter Counter.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 110.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 110.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 110.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 110.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

The cell count results indicate that algae in the negative control flasks exhibited normal log growth, increasing from 1x10e4 cells/mL at time 0 to a mean of 6.9x10e5 cells/mL at test end.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

The inhibition of growth of the alga, Selenastrun capricornutum, following exposure to the test substance was determined in a 72-hour growth test. Cultures of algae were exposed to the test substance at a nominal concentration of 110 mg/L over several algal generations. The concentration of the test substance in the exposure solutions were measured using gas chromatography with flame ionization detection (GCIFID). The exposure concentration was based on the geometric mean of the analyzed solutions, averaged over the three replicates, at test start and at 24-hour intervals throughout the test. The mean analyzed value for the test substance exposure concentration was determined to be 110.1 mg/L. Two measures of growth (biomass and growth rate) were used to determine the effects of the test substance on the algae in comparison to a control. Cell counts were made at 24-hour intervals and the growth curves plotted. Inhibition in biomass or growth rate of 25% or greater was not observed in this experiment, therefore, a definitive test was not performed. The EbC50 and ErC50 values were estimated to be greater than 110.1 mg/L. The 72-hour NOEC value was determined to be 110.1 mg/L.