2-butoxyethyl methacrylate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 03, 2018 to January 05, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

The temperature within the incubator had a recorded range between 20.0 - 21.1 °C and was not maintained within ±1 °C.

Principles of method if other than guideline:

The temperature was still within the specified range of 20±2°C throughout the test. No mortality or abnormal behaviour was observed in the control animals thus any effects seen in the concentrations were due to the test material. In the opinion of the study director, a deviation of +0.1 °C outside the specified variation range had no effect on the results and had no impact on the integrity and validity of the study.

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

Analytical confirmation of the exposure concentrations was not performed.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stock solutions were prepared for both the range-finding and definitive tests by addition of the test sample directly to Elendt M4 medium in a volumetric flask of adequate volume. Calculated volumes of the stock solution were added to nutrient growth medium and made to volume to prepare the test concentrations and provide enough solution for testing and subsequent water quality measurements.
- Controls: An untreated 0 mg/l control in the preliminary test and definitive test.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna.
- Source: From cultures maintained at Chemex Environmental International Ltd since July 2014 and originally sourced from a clone of genotype 5.
- Feeding during test: No.
- Food type: Prior to the test, a suspension of Chlorella vulgaris was supplied.
- Frequency: Each working day.

ACCLIMATION
- Acclimation period: No.

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES: Garvid isolation occured on March 05, 2018. Age of Daphnia magna at the start of the test was ≤ 24 hours.

Test type:

static

Water media type:

other: Elendt M4 reconstituted Daphnia water

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

The number of immobilised Daphnia magna was recorded after 24 and 48-hour exposure periods.

Test temperature:

Temperature range within incubator throughout test: 20.0 - 21.1 °C (required: 20 ± 2 °C maintained to ±1 °C).

pH:

Initial pH at 0 hours: 7.06 (required: 6 - 9).
pH range in control and test concentrations throughout test: 7.06 - 8.07.

Dissolved oxygen:

Initial dissolved oxygen at 0 hours: 5.83 mg/l.
Dissolved oxygen range in control and test concentrations throughout the test: 5.33 - 6.10 mg/l (required: ≥3 mg/l).

Nominal and measured concentrations:

Nominal preliminary test concentrations: 0 (control), 0.1, 1, 10, and 100mg/l (range-finding).
Nominal definitive test concentrations: 0 (control), 12.5, 25, 50 100, and 200 mg/l.

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass dishes.
- Type: To limit aerial contamination of the test vessels and reduce evaporative losses, the vessels were covered with a perspex sheet.
- Material, size, headspace, fill volume: 40 ml.
- Aeration: No.
- Type of flow-through. Static.
- No. of organisms per vessel: Five Daphnia were transferred to each control and test concentration vessel using a wide bore glass tube in the minimum amount of culture water (<0.5ml).
- No. of vessels per concentration: Four replicates at each concentration.
- No. of vessels per control: Four.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dilution water for the test and culture media (reconstituted Elendt M4 media prepared according to OECD 202) was deionised water. Nutrient stock solutions were prepared and added to the dilution water to obtain the culture medium. The pH was 7.06 at test initiation.
- Culture medium different from test medium: Reconstituted Elendt M4 media was used for the test and culture media.
- Intervals of water quality measurement: The pH (to 0.01), dissolved oxygen mg/l (to 0.01) and temperature (to 0.1°C) measurements were taken at 0 hours on remaining test solution, and at 48-hour endpoint on pooled replicates for each test and control solution. Temperature of incubation was recorded at 0, 24 and 48 hours.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours dark.
- Light intensity: 406 lux at 0 hours and 450 lux at 48 hours.

EFFECT PARAMETERS MEASURED: Immobilisation.

VEHICLE CONTROL PERFORMED: No.

RANGE-FINDING STUDY
- Test concentrations: A preliminary (range-finding) test was conducted at concentrations of 0 (control), 0.1, 1, 10 and 100mg/l.
- Results used to determine the conditions for the definitive study: Yes, data from the preliminary test identified the 48-hour EC50 as being >100mg/l.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

536 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Determined by Maximum Likelihood-Probit

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

152 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Determined by Maximum Likelihood-Probit

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Determined by Steel’s Many-One Rank Test

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Determined by Steel’s Many-One Rank Test

Details on results:

- Behavioural abnormalities: Abnormalities were observed during the test period, as 2 individuals in 100mg/l at 24 hours, 17 individuals in 200mg/l at 24 hours and 4 individuals in 200mg/l at 48 hours showed slower movement.
- Other biological observations: No test concentration immobilised all twenty Daphnia after 48-hours. The highest concentration where no immobilisation occurred was 50mg/l.
- Mortality of control: None (0%) of the twenty control Daphnia maintained in dilution water were immobilised and none were trapped in the meniscus during the study. This fulfills the control validity criteria of the study as the percentage of immobilisation did not exceed 10%, confirming that the test organisms were of suitable health for use in the study.
- Any observations that might cause a difference between measured and nominal values: No.
- Effect concentrations exceeding solubility of substance in test medium: The solubility of the test substance was 395.7 mg/L (EPI Suite prediction). The 24-hour EC50 was estimated to be 536 mg/l based on Maximum Likelihood-Probit in ToxCalc v5.0, which is greater than the solubility of the test substance in the test medium.

Results with reference substance (positive control):

A separate GLP study (ENV 11395) was conducted from 18 to 20 January 2017 to monitor the sensitivity of the test animals and test procedures. The reference study gave a 24 hour EC50 of 1.4mg/l of potassium dichromate which was within the acceptable range 0.6 mg/l to 2.1 mg/l as specified in Technical Corrigendum to ISO6341.

Validity criteria fulfilled:

yes

Conclusions:

2-Butoxyethyl methacrylate resulted in a 48-hour EC50, NOEC, and LOEC of 152, 100, and 200 mg/l, respectively, in exposed Daphnia magna. The registered substance is not regarded as being an acute hazard to aquatic invertebrates based on this experimental data given that the 48-hour EC50 is >1 mg/l (CLP Regulation (EC) No 1272/2008).

Executive summary:

To determine the 48-hour EC50 of 2-butoxyethyl methacrylate and clarify whether this substance represents a short-term toxicity hazard to aquatic invertebrates, an experiment was undertaken with Daphnia magna according to Good Laboratory Practise (GLP) and OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test). The 48-hour EC50 is defined as the concentration that will immobilise 50 % of exposed Daphnia magna after a 48-hour exposure period. A preliminary range-finding test was undertaken at 0 (control), 0.1, 1, 10 and 100mg/l, the results of which were used to define the definitive test concentrations of 0 (control), 12.5, 25, 50, 100, and 200 mg/l. The test volume was 25 ml per each 40 ml glass dish, with Elendt M4 reconstituted water used as the culture and test media. The results of a former GLP-compliant study in potassium dichromate, for which a 24-hour EC50 of 1.4 mg/l was calculated, were included to provide reference substance data.

All validity criteria for the study were satisfied. The NOEC and LOEC were determined to be 100 and 200 mg/l, respectively. The calculated 24-hour EC50 (536 mg/l) exceeded the water solubility value for 2-butoxyethyl methacrylate of 395.7 mg/l (EPI Suite prediction), however, the 48-hour EC50 was determined to be 152 mg/l. As the 48-hour EC50 is above 100mg/L , it can be concluded that 2- butoxyethyl methacrylate is not acutely toxic to aquatic invertebrates.

Description of key information

A 48-hour EC50, NOEC, and LOEC of 152, 100, and 200 mg/l, respectively, were determined following a 48-hour acute aquatic toxicity experiment in which Daphnia magna were exposed to 2-butoxyethyl methacrylate. As the 48-hour EC50 is greater than 1 mg/l, the registered substance is not considered to be a acutely toxic to aquatic invertebrates (CLP Regulation (EC) No 1272/2008).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

152 mg/L