7-hydroxy-3-(4-methoxyphenyl)-4-benzopyrone

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:

04 March - 20 November 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

not specified

GLP compliance:

yes

Specific details on test material used for the study:

- Lot No. of test material: 07-170-FIL-2/3
- Appearance: White powder
- Expiration date: May 2010
- Purity: 98.4%
- Storage condition of test material: Ambient

Analytical monitoring:

yes

Details on sampling:

The concentration of test substance was determined in each test solution at 0 and 48 hours by standard analytical methods that were validated prior to dosing (not described in the report).

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test material was determined to be insoluble in water. Therefore, a water-soluble fraction was prepared by adding the required nominal amount of test substance in moderately hard synthetic freshwater and mixing the solution for 20-24 hours. After this mixing time, the undissolved test substance was separated from the solution and only this water-soluble fraction was used for testing.
- Controls: Untreated control and solvent control
- Chemical name of vehicle: Dimethyl formamide (DMF)
- Concentration of vehicle in test medium: DMF was added as a solvent to the water-soluble fraction at 2.0 mL per 2 L dilution water.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Source: STILLMEADOW, Inc. culture laboratory
- Age: No greater than 24 hours old at dosing
- Feeding during test: No

ACCLIMATION
Before dosing, the daphnids were held in water of the quality used in the test.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

Range-finding: 100 mg/L CaCO3
Definitive: 85 mg/L CaCO3

Test temperature:

20 ± 2°C (actual temperature in definitive test: 21 - 22°C)

pH:

Range-finding: pH 8.4
Definitive: measured pH
- 0 hours: 7.7 - 7.8
- 48 hours: 7.2 - 7.6

Dissolved oxygen:

60 - 105% saturation at dosing

Measured dissolved oxygen:
- 0 hours: 9.0 - 9.9 mg/L
- 48 hours: 7.9 - 8.5 mg/L

Salinity:

No data

Conductivity:

Definitive test (measured):
- 0 hours: 280 - 290 µmhos/cm
- 48 hours: 295 - 300 µmhos/cm

Nominal and measured concentrations:

Nominal concentrations: 100 and 1000 mg/L
Measured: See table 1

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers
- Material, size, headspace, fill volume: 250 mL glass beakers; filled with 200 mL of the appropriate solution
- Aeration: No
- No. of organisms per vessel: 10 daphnids per vessel
- No. of vessels per concentration: 3 replicates per concentration
- No. of vessels per control: one control group, 3 replicates
- No. of vessels per vehicle control (replicates): one solvent control group (1.0 mL DMF in 1000 mL dilution water added to the stock solution), 3 replicates

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Moderately hard laboratory freshwater

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16 hours light/ 8 hours dark cycle

EFFECT PARAMETERS MEASURED: At 24 and 48 hours following dosing, each beaker was examined for immobility and the number of live daphnids was recorded.

VEHICLE CONTROL PERFORMED: yes

RANGE-FINDING STUDY
- Test concentrations: 1.0, 10, 50, 100, 500 and 1000 mg/L
- Results used to determine the conditions for the definitive study: Immobility was less than 10%.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mobility: A mobility rate of 100% was observed in organisms treated with 100 mg/L and a 73% mobility rate was observed in organisms treated with 1000 mg/L.
- Mobility of control: A mobility rate of 97% was observed in the control organisms.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: At 1000 mg/L, the test solutions were cloudy and after 24 hours, the water was too turbid to count.

Table 1: Mobility data

Nominal concentration	Replicate	Number of mobile organisms
		0 hours	24 hours	48 hours
0	A	10	10	9
	B	10	10	10
	C	10	10	10
100	A	10	10	10
	B	10	10	10
	C	10	10	10
1000	A	10^a	*	8^b
	B	10^a	*	7^b
	C	10^a	*	7^b
Solvent control (DMF)	A	10	10	10
	B	10	10	10
	C	10	10	10

* - too turbid to count

^a– water cloudy

^b– organisms lethargic, water cloudy

 

Table 2: Dose verification

	Control	Solvent control DMF	mg/L
Time point	NA	NA	100	1000
Day 0	0.53	0.57	1.03	4.96
48 hour	0.54	NA	0.60	2.06

 

 

Validity criteria fulfilled:

yes

Remarks:

Both the range-finding and definitive test control immobility was less than 10%.

Conclusions:

The 48 hour EC50 of Formononetin was determined to be >1000 mg/L. The NOEC for survival was 100 mg/L.

Description of key information

A GLP study was performed in accordance with OECD Guideline 202, to determine the toxicity of the test substance, Formononetin, to the freshwater invertebrate Daphnia magna in a 48 hour static test. The 48 hour EC50 of Formononetin was determined to be >1000 mg/L and the NOEC for survival was 100 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 000 mg/L