Methyl benzoylformate

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

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:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling: Triplicate samples from the freshly prepared test medium of the only test concentration and the control were taken at the start of the test and at test medium renewal at Day 1.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentration during the test period, triplicate samples from the test medium of the only test concentration and the control were collected at test medium renewal at Day 1 (after 24 hours of exposure) and at the end of the test (after 48 hours).
All samples were diluted with acetonitrile. Therefore one part of the sample was diluted with nine parts acetonitrile.
One additional sample of the control blank and the dilution solvent was taken at test start, test medium renewal and test end without any sample treatment.
- Storage of Samples: All samples were stored (at May 27 to 29, 2015) in a freezer (≤ -10 °C), protected from light until analysis was performed. At June 01, 2015 the samples from the freshly prepared test medium from test start and from the test medium renewal at Day1 (after 24 hours of exposure) were analysed.
At June 18, 2015 the samples of the aged test medium from test medium renewal at Day 1 (after 24 hours of exposure) and from the end of the test (after 48 hours) were analysed.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
Before test start and before the test medium renewal (after 24 hours of exposure) the test medium of nominal 120 mg test item/L was prepared by dissolving 56.4 and 57.0 mg test item into 470 and 475 mL test water by intense stirring for 30 minutes in the dark.
The test media were prepared just before introduction of the Daphnia (= start of the test) and test medium renewal on Day 1 respectively.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain: Daphnia magna (Straus), clone 5
- Source: The Daphnia introduced in the test were taken from ibacon's in-house laboratory culture.
- Age at study initiation (mean and range, SD): From 1.75 to 18.25 hours old
- Method of breeding: The Daphnia were bred in the laboratories of ibacon under similar temperature and light conditions as used in the test. The cultivation of the parental Daphnia was performed in Elendt M4 medium. The test organisms were not first brood progeny. The Daphnia in the stock culture were fed at least on all working days with green algae (Desmodesmus subspicatus) freshly grown in the laboratories of ibacon.
- Feeding during test: No

ACCLIMATION
Was not necessary, since the test was performed in the same medium as the culturing

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Remarks on exposure duration:

in the dark

Hardness:

1.068 mmol/L as CO3 2-

Test temperature:

19 to 20 °C in the freshly prepared media;
20 °C in the aged test media

pH:

7.6 to 8.5 in the freshly prepared media;
7.6 to 8.1 in the aged test media; and thus the pH-value did not vary by more than 1.5 units

Dissolved oxygen:

8.3 to 8.9 mg/L in the freshly prepared media;
8.4 to 8.7 mg/L in the aged test media

Nominal and measured concentrations:

120 mg test item/L nominal concentration corresponding to 39.6 mg test item/L geometric mean measured concentration and a control

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers of 100 mL volume containing approximately 60 mL of test medium. The test vessels were covered with a lid to reduce the loss of water due to evaporation and to avoid the entry of dust into the solutions.
- Aeration: No
- Type of test procedure: A semi-static test system with a test medium renewal on Day 1 (after 24 hours of exposure) was chosen to keep the concentrations of test item as constant as possible in the test media.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted Water (Elendt "M4")
- Alkalinity: 0.348 mmol/L (tested May 28, 2015)
- Conductivity: 630 μS/cm (tested in the fresh test media)
- Culture medium different from test medium: No
- Intervals of water quality measurement: The water temperature, pH-values and the dissolved oxygen concentrations were determined in all freshly prepared and aged test media of each treatment group.

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: No light
- Light intensity: The light intensity was 0 lux (measured once during the test).

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The mobility of the Daphnia was determined by visual observation after 24 and 48 hours. Those animals that are not able to swim within 15 seconds after gentle agitation of the test beaker were considered to be immobile (even if they could still move their antennae).

TEST CONCENTRATIONS
- Range finding study: Pre-experiments were performed to determine a suitable concentration range and to establish suitable methods to prepare the
test solutions. In the pre-experiments 100, 10, 1 and 0.1 mg test item/L were tested. In all concentrations, no effect was observed. A second pre-test over 24 hours duration was performed at 120 mg test item/L. Also no effects on the daphnids were observed. The quantification of the test item was performed using liquid chromatography with UV-vis detection (HPLC/UV-vis method). The pre-experiments were not performed in compliance with the
GLP-Regulations and will be excluded from the Statement of Compliance in the final report, but the raw data of these tests will be archived under the project number of the present study.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 39.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 120 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 39.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

After 48 hours of exposure in the dark, no immobilisation of the test animals was observed in the control. At the only geometric mean measured test concentration of 39.6 mg test item/L (120 mg test item/L based on nominal concentration), one test animal was immobile at the observation after 48 hours. However this immobilisation rate was not considered as a significant toxic effect, because according to the test guidelines an immobilisation rate of even 10 % is tolerated for control Daphnia in the acute test.
No appearance of the test item in the test medium have been observed during the copmlete test.

- Mean Recovery in the Test Samples:
Freshly prepared: 80% (n = 4, RSD 3%)
Aged test media: 14% (n = 4, RSD 15%)

Results with reference substance (positive control):

For the evaluation of the quality of the Daphnia clone and the consistency of the experimental conditions, the reference item potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions. In the most recent test with the reference item potassium dichromate performed in January 2015 (study code 88293220) the EC50 after 24 hours was determined to be 1.85 mg test item/L indicating that the sensitivity of the Daphnia was consistent with the level proposed by the OECD 202 guideline (EC50-24 h between 0.6 and 2.1 mg potassium dichromate/L).

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the test, the 48 hour EC50 of the test material to Daphnia magna was determined to be 120 mg/l (nominal).

Executive summary:

In this guideline (OECD 202) study, conducted with GLP certification, the 48 hour EC50 test material (EC 239-263-3) to Daphnia magna was determined to be 120 mg/l (nominal). A single test concentration was tested (limit test), to determine if the test material posed a hazard to the aquatic environment. The EC50 observed was outside the criteria for classification for hazard to the aquatic environment under the EU Classification, Labelling, and Packaging (CLP) regulation (1272/2008).

Description of key information

 Study carried out according to guideline and with GLP compliance. 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

120 mg/L

Additional information

The short-term toxicity to aquatic invertebrates has been tested in a semi-static GLP guideline study according to OECD 202 using Daphnia magna (ibacon GmbH 2015). Due to the results of a preliminary study a limit test using a concentration of 120 mg/L has been conducted. Additionally, due to the photosensitivity of the test item the test has been conducted in the dark. After 48 h of exposure no sigificant effects have been observed. Therefore, the EC50 was determined to be > 120 mg/L (nominal) and > 39.6 mg/L (geometric mean measured).

The quantification of the test item was performed using liquid chromatography with UV detection. In the freshly prepared test media at the start of the test and at the renewal of the test media (after 24 hours of exposure) recoveries of the only nominal test concentration varied between 78 and 82%. In the aged test media after 24 and 48 hours test duration, the recoveries of the nominal values varied between 12 and 16%. The rapid dissipation of the test item during the exposure period is conclusively explained by its specific substance properties (photoinitiator and hydrolytically unstable). Nevertheless, every effort (semi-static test design and reduced light intensity) has been taken to test the parent substance.

Therefore, the test item is with high probability not acutely harmful to aquatic invertebrates.