7-methyl-2H-1,3-benzoxazine-2,4(3H)-dione

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
VEGA v1.1.4

2. MODEL (incl. version number)
Daphnia Magna LC50 48h (EPA) 1.0.7

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
O=C1Oc2ccccc2(C(=O)N1)

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
[Explain how the model fulfils the OECD principles for (Q)SAR model validation. Consider attaching the QMRF or providing a link]
See QMRF

5. APPLICABILITY DOMAIN
[Explain how the substance falls within the applicability domain of the model]
- Descriptor domain:
Not applicable as the QSAR is based on structural alerts.
- Structural and mechanistic domains:
All atom entered fragments of the compound have been found in the compounds of the training dataset.
- Similarity with analogues in the training set:
Similarity index = 0.808. Although only moderately similar structures are present in the training set, these contain the most important structures (benzene ring with OC(=O)N1 group) and predictions for these substances are highly accurate.
- Other considerations (as appropriate):

6. ADEQUACY OF THE RESULT
[Explain how the prediction fits the purpose of classification and labelling and/or risk assessment]
The QSAR prediction is used to support the experimental result from a structural analogue and to support the read-across (limited influence of the methyl group).

Qualifier:

according to guideline

Guideline:

other: Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals

Specific details on test material used for the study:

SMILES: O=C1Oc2ccccc2(C(=O)N1)

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

1.13 mg/L

Basis for effect:

mortality

Validity criteria fulfilled:

not applicable

Conclusions:

Using the VEGA QSAR model for Daphnia Magna LC50 48h (EPA) v1.0.7, an LC50 of 1.13 mg/L was estimated.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Qualifier:

according to guideline

Guideline:

other: Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals

Specific details on test material used for the study:

SMILES: C1(=O)c2c(cc(C)cc2)OC(=O)N1

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

0.887 mg/L

Basis for effect:

mortality

Validity criteria fulfilled:

not applicable

Conclusions:

Using the VEGA QSAR model for Daphnia Magna LC50 48h (EPA) v1.0.7, an LC50 of 0.887 mg/L was estimated.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

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)

Version / remarks:

Adopted April 13, 2004

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: At the end of the exposure period, the replicates were pooled at each concentration before sampling.
- Sampling method:
Frequency at t=0 h and t=48 h
Volume 2.0 mL from the approximate centre of the test vessels
- Sample storage conditions before analysis: Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility.

Vehicle:

yes

Remarks:

water

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The batch of 3,4-dihydro-2,4-dioxo-1,3-2h-benzoxazine tested was a white powder with a purity of approximately 99% which was completely soluble in test medium at the concentrations tested. No correction was made for the purity/composition of the test item.
Preparation of test solutions started with the highest concentration of 100 mg/L applying one hour of magnetic stirring followed by a 20-minute treatment period of ultrasonic waves to accelerate dissolution of the test item in medium. Only a few floating undissolved particles were observed in the highest test concentration, however they were considered negligible which was confirmed in the analytical analysis of the test solutions (measured concentration = 99.2 mg/L). Lower test concentrations were prepared by subsequent dilutions of the highest concentration in test medium. All test solutions were clear and colorless at the end of the preparation procedure.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain/clone: In-house laboratory culture with a known history.
- Justification for species other than prescribed by test guideline: This system has been selected as an internationally accepted invertebrate species.
- Source: In-house laboratory culture with a known history.
- Age of parental stock (mean and range, SD): <4 weeks
- Feeding during test: no
- Food type: /
- Amount: /
- Frequency: /

ACCLIMATION
- Acclimation conditions (same as test or not): same as test
- Type and amount of food: Daily, a suspension of fresh water algae

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

19-20°C

pH:

7.4-8.1

Dissolved oxygen:

7.5-8.4 mg/L

Nominal and measured concentrations:

0.10, 1.00, 10 and 100 mg/L.
The measured concentrations were at the level of nominal throughout the test duration (94-96%).

Details on test conditions:

TEST SYSTEM
- Test vessel: 60 mL, all-glass
- Type (delete if not applicable): static
- Aeration: No aeration of the test solutions.
- No. of organisms per vessel: 5 per vessel containing 50 mL of test solution
- No. of vessels per concentration (replicates): 4 for the control and the highest test concentration.
2 per intermediate test concentration.
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
M7, as prescribed by Dr. Elendt-Schneider (Elendt, B.-P., 1990: Selenium deficiency in Crustacea. An ultrastructural approach to antennal damage in Daphnia magna Straus. Protoplasma 154, 25-33).

Composition of medium M7:
Adjusted ISO medium: the following chemicals (analytical grade) are dissolved in tap water purified by Reverse Osmosis (RO-water, GEON Waterbehandeling, Berkel-Enschot, The Netherlands):
Macro salts: CaCl2.2H2O 211.5 mg/L
MgSO4.7H2O 88.8 mg/L
NaHCO3 46.7 mg/L
KCl 4.2 mg/L
Medium M7: trace elements, macronutrients and vitamins are added to freshly prepared ISO medium to reach the following concentrations:
Trace elements:
B 0.125 mg/L
Fe 0.05 mg/L
Mn 0.025 mg/L
Li, Rb and Sr 0.0125 mg/L
Mo 0.0063 mg/L
Br 0.0025 mg/L
Cu 0.0016 mg/L
Zn 0.0063 mg/L
Co and I 0.0025 mg/L
Se 0.0010 mg/L
V 0.0003 mg/L
Na2EDTA.2H2O 2.5 mg/L
Macro nutrients:
Na2SiO3.9H2O 10.0 mg/L
NaNO3 0.27 mg/L
KH2PO4 0.14 mg/L
K2HPO4 0.18 mg/L
Vitamins: Thiamine 75.0 µg/L
B12 1.0 µg/L
Biotin 0.75 µg/L
The hardness: 180 mg/L expressed as CaCO3 and the pH: 7.7 ± 0.3.


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: A daily photoperiod of 16 hours
- Light intensity: not specified

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Immobility (including mortality) At 24 hours and at 48 hours.
pH and Dissolved oxygen At the beginning and at the end of the test, for the highest concentration and the control.
Temperature of medium Continuously in a temperature control vessel, beginning at the start of the test.


VEHICLE CONTROL PERFORMED: yes (medium)

RANGE-FINDING STUDY
- Test concentrations: 0.10, 1.00, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: combined limit/range-finding study

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 88 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: corresponds to nominal concentration of 100 mg/L

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 88 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: corresponds to nominal concentration of 100 mg/L

Results with reference substance (positive control):

The actual responses in this reference test with K2Cr2O7 are within the ranges of the expected responses at the different concentrations, i.e. the 48h-EC50 was between 0.3 and 1.0 mg/L. Hence, the sensitivity of this batch of D. magna was in agreement with the historical data collected at Charles River Den Bosch.

The 48h-EC50 was 0.59 mg/L with a 95% confidence interval between 0.53 and 0.72 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the 48h-EC50 for Daphnia magna exposed to 3,4-dihydro-2,4-dioxo-1,3-2h-benzoxazine was beyond the range of concentrations tested, i.e. exceeded an average exposure concentration of 88 mg/L (nominal concentration of 100 mg/L).

Executive summary:

The objective of the study was to evaluate 3,4-dihydro-2,4-dioxo-1,3-2h-benzoxazine for its ability to generate acute toxic effects on the mobility of Daphnia magna during an exposure period of 48 hours and, if possible, to determine the EC₅₀at 24 and 48 hours of exposure.

The study procedures described in this report were based on the OECD guideline No. 202, 2004.

The batch of 3,4-dihydro-2,4-dioxo-1,3-2h-benzoxazine tested was a white powder with a purity of approximately 99% which was completely soluble in test medium at the concentrations tested.

A combined limit/range-finding test was performed. Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to a nominal concentration of 100 mg/L, in a limit test. In addition ten daphnids per group (5 per replicate, duplicate) were exposed to nominally 0.10, 1.0 and 10 mg/L in the combined range-finding test. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test.

Samples taken from the limit concentration were analysed. The measured concentration at the start of the test was 99 mg/L and had decreased to 79% relative to nominal at the end of the test. Based on these results, effect parameters were expressed in terms of the average exposure concentration, calculated to be 88 mg/L.

No immobility was observed in the control and at any of the test concentrations throughout the exposure period.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

In conclusion, the 48h-EC₅₀for Daphnia magna exposed to 3,4-dihydro-2,4-dioxo-1,3-2h-benzoxazine was beyond the range of concentrations tested, i.e. exceeded an average exposure concentration of 88 mg/L (nominal 100 mg/L).

Reference 4

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 95.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: corresponds to nominal concentration of 100 mg/L

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 95.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: corresponds to nominal concentration of 100 mg/L

Results with reference substance (positive control):

The actual responses in this reference test with K2Cr2O7 are within the ranges of the expected responses at the different concentrations, i.e. the 48h-EC50 was between 0.3 and 1.0 mg/L. Hence, the sensitivity of this batch of D. magna was in agreement with the historical data collected at Charles River Den Bosch.

The 48h-EC50 was 0.59 mg/L with a 95% confidence interval between 0.53 and 0.72 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The OECD 202 test of a structurally similar substance was used to assess the short-term toxicity to aquatic invertebrates. The 48h-EC50 for Daphnia magna exposed to 3,4-dihydro-2,4-dioxo-1,3-2h-benzoxazine (CH02586) was beyond the range of concentrations tested, i.e. exceeded an average exposure concentration of 88 mg/L (nominal concentration of 100 mg/L), corresponding to 95.6 mg/L CH03131. Based on this result, no effects are expected for CH03131 at concentrations up to 95.6 mg/L or higher. No GHS classification for aquatic toxicity is required for CH03131.

Description of key information

Based on read-across from a structural analogue, the EC50 for CH03131 is >95.6 mg/L and no classification is required for CH03131. This is further supported by QSAR predictions (EPA Daphnia QSAR).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

95.6 mg/L