Boronic acid, (4-ethylphenyl)-

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:

2007-07-11 to 2008-01-29

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:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.88, 1.94, 4.27, 9.39,20.66, 45.46 or 100 mg/L

- Sampling method: Samples were taken from all concentrations. After preparation of the test media the analytical values were determined. The maintenance of the test material concentrations was confirmed by determination of further samples after a period of 48 hours.

- Sample storage conditions before analysis: All samples were stored under the same conditions as the vessels with Daphnia magna and afterwards sent for analysis

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The test media (reconstituted water and test item) were freshly prepared. Therefore, the calibrated flask with test medium was treated in an ultrasonic device for 1 hour. Subsequently, the preparation was stirred with a magnetic stirrer for further 23 hours. The formulation was then passed through a single use syringe filter (pore size 0.2 µm). The filtrate was used for the study.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation: not older than 24 hours
- Source: Merck KGaA, Darmstadt, Institute of Toxicology
- Feeding during test: no

ACCLIMATION
In preparing for a new study, juvenile Daphnia magna were separated and placed in 60 mL of reconstituted water. The water was renewed and the Daphnia magna were fed with a Suspension of fresh water algae once a week. New-born Daphnia magna were separated and allocated to the different dose groups.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

14° dH (about 250 mg/L CaCO3)

Test temperature:

20 - 21 °C

pH:

7.74 – 7.95

Dissolved oxygen:

94.1 – 97.1 %

Nominal and measured concentrations:

Nominal conc.: 0.88, 1.94, 4.27, 9.39, 20.66, 45.46 or 100 mg/L;
Measured conc.: between 101.1 - 103.4 % at the start and 97.7 - 103.4 % of nominal test item concentration at the end of test

Details on test conditions:

TEST SYSTEM
- Test vessel: glass test vessels
- Type: open
- Volume of solution: 10 mL
- 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, 1990)
- Culture medium different from test medium: the same
- Intervals of water quality measurement: at the beginning and at the end of the test

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light - 8 hours dark regime

EFFECT PARAMETERS MEASURED: the number of immobilized daphnids were recorded after 24 and 48 hours.


RANGE-FINDING STUDY
- Test concentrations: 0.1, 1.0, 10.0, 50.0, and 100.0 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

10.58 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95 % confidence interval: 8.09 - 13.82 mg/L

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

36.67 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95 % confidence interval: 30.78 - 43.70 mg/L

Details on results:

Clinical observation:
Daphnia magna exposed to nominal concentrations of 4.27 up to 100 mg/L led to immobilized daphnia. Concentrations of 0.88 and 1.94 mg/L revealed no biological effects.

Clinical findings:

The concentrations of the preparations and immobilization data of the study are shown in the following table:

 

Nominal concentration [mg/L]	Immobilized/exposed Daphnia magna
	24 hours	48 hours
0.00	0/20	0/20
0.88	0/20	0/20
1.94	0/20	0/20
4.27	0/20	4/20
9.39	0/20	9/20
20.66	0/20	14/20
45.46	16/20	20/20
100.00	20/20	20/20

 

Environmental conditions

pH, oxygen concentrations, and temperature during the study were inconspicuous.

 

Nominal concentration [mg/L]	Start of the experimental part (t = 0 hour)		End of the experimental part (t = 48 hours)
	pH	O2 [%]	pH	O2 [%]
0.00	7.95	97.1	7,91	95.3
0.88	7.94	96.4	7.90	94.6
1.94	7.95	96.6	7.90	96.0
4.27	7.90	95.9	7.84	94.8
9.39	7.88	96.1	7.84	94.3
20.66	7.87	95.6	7.83	94.1
45.46	7.88	96.3	7.81	95.2
100.00	7.79	96.2	7.74	94.6

 

The temperature in the control test vessel was 20 - 21°C.

No remarkable observations were made concerning the appearance of the test media. All test media were clear solutions and remained clear throughout the entire test period.

 

Analytical results

 

Group No.	Sample No.	Nominal concentration [mg/L]	Time after preparation [hours]	Mean analytical concentration [mg/L]	% of nominal concentration
1	1	0.88	0 (start)	0.91	103.4
	8		48 (end)	0.91	103.4
2	2	1.94	0 (start)	1.97	101.5
	9		48 (end)	1.99	102.6
3	3	4.27	0 (start)	4.40	103.0
	10		48 (end)	4.33	101.4
4	4	9.39	0 (start)	9.55	101.7
	11		48 (end)	9.53	101.5
5	5	20.66	0 (start)	21.13	102.3
	12		48 (end)	20.18	97.7
6	6	45.46	0 (start)	45.95	101.1
	13		48 (end)	46.42	102.1
7	7	100.00	0 (start)	102.30	102.3
	14		48 (end)	101.09	101.1

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of this study, the 48-h EC50 value was 10.58 mg/L (95 % CI: 8.09 – 13.82 mg/L).

Executive summary:

The acute toxicity of the test item to Daphnia magna was assessed in a 48-h Acute Immobilisation Test according to OECD TG 202. For this purpose, juvenile Daphnia magna were exposed to an aqueous test item solution for over 48 hours, under defined conditions. Based on the results obtained from a static non-GLP preliminary experiment, daphnids were exposed to reconstituted water or to test material concentrations of nominal 0.88, 1.94, 4.27, 9.39, 20.66, 45.46 or 100 mg/L in an open static test system. The study comprised of four test vessels per concentration containing five Daphnia magna each, i.e. 20 daphnids per concentration (test medium group) and control group. The purpose of the analytical part of this study was to verify the concentration of the test item in the test medium. The limit of quantification of the analytical method was 0.02 mg/L. The analytically determined concentrations were between 101.1 - 103.4 % at the Start and 97.7- 103.4 % at the end of exposure. During the experimental phase of the study, the test material concentrations could be maintained at > 80 % of the initial concentrations. Therefore, the EC₅₀ values were calculated based on the nominal concentrations. The nominal concentrations from 4.27 up to 100.0 mg/L led to immobilized daphnia. Concentrations of 0.88 and 1.94 mg/L revealed no biological effects. Under the test conditions, the 24-h EC₅₀ of the item was determined to be 36.67 mg/L (95 % CI: 30.78 – 43.70 mg/L) and the 48-h EC₅₀ was determined to be 10.58 mg/L (95 % CI: 8.09 – 13.82 mg/L).

Description of key information

The test item showed a 48-h EC₅₀ of 10.58 mg/L (95 % CI: 8.09 – 13.82 mg/L) in a study performed according to OECD Guideline 202 (reference 6.1.3-1).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

10.58 mg/L

Additional information

The acute toxicity of the test item to Daphnia magna was assessed in a 48-h Acute Immobilisation Test according to OECD TG 202. For this purpose, juvenile Daphnia magna were exposed to an aqueous test item solution for over 48 hours, under defined conditions. Based on the results obtained from a static non-GLP preliminary experiment, daphnids were exposed to reconstituted water or to test material concentrations of nominal 0.88, 1.94, 4.27, 9.39, 20.66, 45.46 or 100 mg/L in an open static test system. The study comprised of four test vessels per concentration containing five Daphnia magna each, i.e. 20 daphnids per concentration (test medium group) and control group. The purpose of the analytical part of this study was to verify the concentration of the test item in the test medium. The limit of quantification of the analytical method was 0.02 mg/L. The analytically determined concentrations were between 101.1 - 103.4 % at the Start and 97.7- 103.4 % at the end of exposure. During the experimental phase of the study, the test material concentrations could be maintained at > 80 % of the initial concentrations. Therefore, the EC₅₀ values were calculated based on the nominal concentrations. The nominal concentrations from 4.27 up to 100.0 mg/L led to immobilized daphnia. Concentrations of 0.88 and 1.94 mg/L revealed no biological effects. Under the test conditions, the 24-h EC₅₀ of the item was determined to be 36.67 mg/L (95 % CI: 30.78 – 43.70 mg/L) and the 48-h EC₅₀ was determined to be 10.58 mg/L (95 % CI: 8.09 – 13.82 mg/L).