Reaction mass of 2-dodecylhexadecyl methacrylate and 2-Tetradecyloctadecyl methacrylate

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:

19 September 2019- 27 September 2019

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:

yes

Remarks:

see 'principles of method if other than guideline'

Principles of method if other than guideline:

The room temperature was above maximum limits throughout the tests by a maximum of 1.7ºC. This deviation is not thought to have had a significant impact on the overall test result as the controls met all relevant validity criteria, and the test material vessels matched the controls. The temperature in the definitive test was still maintained within a 0.7 ºC range.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature in the dark

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: In order to determine an appropriate test preparation method, an assessment was made of the material’s behaviour in deionised water. A 1000 mg/l stock was prepared in deionised water, and the resulting mixture was then stirred for one hour, left to settle for a further one hour, and its behaviour assessed. As the material was observed to be poorly soluble, it was stirred again for approximately 19 hrs, left to settle for one hour, then its behaviour was reassessed. The material was observed to be poorly soluble so was prepared by Water Accommodated Fractions (WAFs). Test material stocks were individually prepared by weighing out an appropriate amount of test material, adding US EPA culture medium and stirring for approximately 20h.
The stocks were then left to settle for 1h and the mid column of the stock was siphoned off, taking care to avoid siphoning any undissolved material.Test material stocks were prepared for the range-finding test

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: 278/4
- Source (laboratory, culture collection): SAMS Limited
- Method of cultivation: Freshwater with nutrient medium (3N=BBM+V) was autoclaved at 120 ºC for 15 minutes. Pre-cultures in the exponential growth phase were then prepared from stock laboratory cultures by inoculating the freshwater 2 to 3 days before test commencement. The pre-culture flasks were incubated at approximately 21 ± 2 ºC under constant illumination and were used as the inoculum source for subsequent toxicity tests.

ACCLIMATION
- Acclimation period: 2 to 3 days
- Culturing media and conditions (same as test or not): Same as test
- Any deformed or abnormal cells observed: None reported.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Not specified

Test temperature:

21-24 ± 2 °C

pH:

7.5 ± 0.1

Dissolved oxygen:

Not Specified

Salinity:

Not Specified

Conductivity:

Not Specified

Nominal and measured concentrations:

Nominal concentrations: 100, 320, 1,000, 3,200, 10,000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml borosilicate glass conical flasks
- Material, size, headspace, fill volume: 50 ml of test medium
- Initial cells density: 5 x10^3-10^4 cells per millilitre
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Purified water treated by reverse osmosis followed by electro-deionisation.

OTHER TEST CONDITIONS
- Adjustment of pH: pH of the culture medium was adjusted, if required, by adding 1M HCl, or NaOH to give a pH of 7.5 ± 0.1.
- Photoperiod: Continuous
- Light intensity and quality: Light intensity values (4440 to 8880 lx) were measured daily during the test.

EFFECT PARAMETERS MEASURED :
- Determination of cell concentrations:fluorimeter; haemocytometer, Sedgewick-Rafter chamber

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 1,10,100 and 1,000 mg/l
- Results used to determine the conditions for the definitive study: 72h EC50 >1,000

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

5 113 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

9 730 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

3 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control: yes
- Observation of abnormalities: None reported
- Any observations that might cause a difference between measured and nominal values: No
- Effect concentrations exceeding solubility of substance in test medium: No

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 0.661 to 1.719 mg/L

Reported statistics and error estimates:

Where sufficient response was observed, the 24h, 48h and 72h EC(r)50, 72h EC(r)90 and 72h NOEC values were calculated using an appropriate statistical method from the CETIS version 1.8 software.

Validity criteria fulfilled:

yes

Conclusions:

Reaction Mass of 2-Propenoic acid, 2-methyl-, 2- dodecylhexadecyl ester and 2-Propenoic acid, 2- methyl-, 2-tetradecyloctadecyl ester exhibited a 72h EC(r)50 value of greater than 10,000 mg/L P. subcapitata.

Executive summary:

A short-term toxicity study to determine the aquatic toxicity phase of Reaction Mass of 2-Propenoic acid, 2-methyl-, 2- dodecylhexadecyl ester and 2-Propenoic acid, 2- methyl-, 2-tetradecyloctadecyl ester to the freshwater unicellular algae (Pseudokirchneriella subcapitata) was determined by a GLP compliant study performed in accordance with OECD 201 test guideline. In order to determine the concentrations to be used in the definitive test a range finding study over 72h to determine the approximate concentrations at which growth rate effects were observed was conducted. Reaction Mass of 2-Propenoic acid, 2-methyl-, 2- dodecylhexadecyl ester and 2-Propenoic acid, 2- methyl-, 2 tetradecyloctadecyl ester was characterised as poorly soluble and therefore was prepared by Water Accommodated Fractions (WAFs). The range-finding test employed four concentrations 1,000, 100, 10 and 1 mg/L with one replicate per concentration; plus, four controls. The 72H EC50 of the range finding test was >1000 mg/L and as a result the following concentration range were used in the definitive study: 100, 320, 1000, 3,200 and 10,000 mg/L. Three replicates were prepared for each test concentration and 6 replicates for the control. Potassium dichromate was used as a reference substance and the results of this test were valid. The 72h EC50 for Reaction Mass of 2-Propenoic acid, 2-methyl-, 2- dodecylhexadecyl ester and 2-Propenoic acid, 2- methyl-, 2-tetradecyloctadecyl as determined by the definitive test was >10,000 mg/L and the 72h NOEC was 3,200 mg/L.

Description of key information

A short-term toxicity study to determine the aquatic toxicity phase of Reaction Mass of 2-Propenoic acid, 2-methyl-, 2- dodecylhexadecyl ester and 2-Propenoic acid, 2- methyl-, 2-tetradecyloctadecyl ester to the freshwater unicellular algae (Pseudokirchneriella subcapitata) was determined by a GLP compliant study performed in accordance with OECD 201 test guideline. In order to determine the concentrations to be used in the definitive test a range finding study over 72h to determine the approximate concentrations at which growth rate effects were observed was conducted. Reaction Mass of 2-Propenoic acid, 2-methyl-, 2- dodecylhexadecyl ester and 2-Propenoic acid, 2- methyl-, 2 tetradecyloctadecyl ester was characterised as poorly soluble and therefore was prepared by Water Accommodated Fractions (WAFs). The range-finding test employed four concentrations 1,000, 100, 10 and 1 mg/L with one replicate per concentration; plus, four controls. The 72H EC50 of the range finding test was >1000 mg/L and as a result the following concentration range were used in the definitive study: 100, 320, 1000, 3,200 and 10,000 mg/L. Three replicates were prepared for each test concentration and 6 replicates for the control. Potassium dichromate was used as a reference substance and the results of this test were valid. The 72h EC50 for Reaction Mass of 2-Propenoic acid, 2-methyl-, 2- dodecylhexadecyl ester and 2-Propenoic acid, 2- methyl-, 2-tetradecyloctadecyl as determined by the definitive test was >10,000 mg/L and the 72h NOEC was 3,200 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

10 000 mg/L

EC10 or NOEC for freshwater algae:

3 200 mg/L