Metformin hydrochloride

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

adopted September 1998

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Duplicate samples from the freshly prepared test media of all test concentrations and the control were taken at the first treatment period (Day 0) and at a treatment period in the second and third week (Days 7 and 16).

For the determination of the stability of the test item under test conditions and of the maintenance of the test item concentrations during the test period, at three dates (Day 2 and 9: 48 hours old and day 19: 72 hours old) duplicate samples from all test concentrations and the control were taken.

- Concentrations: 32, 10, 3.2, 1.0 and 0.32 mg test item/L and a control.
- Sampling method: Duplicate samples from the freshly prepared test media of all test concentrations and the control were taken at the first treatment period (Day 0) and at a treatment period in the second and third week (Days 7 and 16). For the determination of the stability of the test item under test conditions and of the maintenance of the test item concentrations during the test period, at three dates (Day 2 and 9: 48 hours old and day 19: 72 hours old) duplicate samples from all test concentrations and the control were taken.
- Sample storage
conditions before analysis: All samples were stored in a freezer (< - 10°C), protected from light, until analysis was performed.

Vehicle:

no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna (Straus)
- Strain/clone: 5
- Source:ECT Oekotoxikologie GmbH, Bottgerstr. 2 - 14, 65439 Florsheim am Main, Germany.
- Age of parental stock: 7-23 hours
- Feeding during test: yes
- Food type: . Once a week the Daphnia of the stock culture were fed with Tetra Min-extract and at least all other working days with green algae (Desmodesmus subspicatus) freshly grown in the laboratories
- Food ammount: 0.15 mg/day of algal TOC/Daphnia

ACCLIMATION
- Acclimation period: Is not necessary since the breeding is performed in the same kind of test water.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

2.5 mmol/L

Test temperature:

18-22 °C

pH:

6-9

Dissolved oxygen:

>3 mg/L

Nominal and measured concentrations:

0, 0.32, 1.0, 3.2, 10, 32 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL vessels
- Type (delete if not applicable): open
- Fill volume: 80 mL
- Renewal rate of test solution (frequency/flow rate): The test media of all test concentrations and of the control were renewed on Days 2, 5, 7, 9, 12, 14, 16 and 19 of the exposure period (every Monday, Wednesday and Friday). Thus, a total of 9 treatments were performed. At these dates the test animals were carefully transferred by glass tubes from the old test vessels into the freshly prepared test media of the corresponding concentrations.
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ElendT "M4"-Medium
- Alkalinity: 0.9 mmol/L

- Culture medium different from test medium: No
- Intervals of water quality measurement: The pH-values, dissolved oxygen concentrations and water temperatures were measured in all test concentrations and in the control at the start and end of each exposure period. For the measurements at the end of each exposure period, the replicate test vessels of each concentration and the control were pooled before sampling.

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16h light : 8h dark
- Light intensity: 0 - 1200 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): The mortality of the test animals and the number of young were recorded each working day. Dead animals and offspring were removed at the same times.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Test concentrations: 32, 10, 3.2, 1.0 and 0.32 mg test item/L and a control.

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Validity criteria fulfilled:

yes

Conclusions:

The influence of the test item on the survival and reproduction rate of Daphnia magna were determined during an exposure period of 21 days in a dose-response study. The 21-day NOEC values for the reproduction rate and for the survival of the adult test animals were determined to be at least 32 mg test item/L in both cases, i.e. the highest concentration tested.

Executive summary:

Study Design

The study was performed according to the following guidelines and recommendations:

• Commission Directive 2001/59/EC, C.20: "Daphnia magna, Reproduction Test", Official Journal of the European Communities No. L 225/246, dated August 21, 2001.
• OECD Guideline for Testing of Chemicals, No. 211: "Daphnia magna Reproduction Test", adopted September, 1998.

The effects of the test item on the survival and reproduction rate of Daphnia magna were determined during an exposure period of 21 days. Young Daphnia were exposed in a semi-static test to aqueous test media containing the test item at various concentrations. The mortality rate, the reproduction rate and symptoms of intoxication were compared with corresponding parameters in the control.

The following test concetrations were applied: 32, 10, 3.2, 1.0 and 0.32 mg test item/L and a control.
The quantification of the test item was performed using liquid chromatography (HPLC-method).

Results

No particular signs of intoxication were observed in the test animals during the test. No significant toxic effect of the test item on the mean reproduction rate could be determined for all tested concentrations.

Effect concentrations have been determined as follows:

21-days NOEC (Reproduction Rate): ≥ 32 mg/L
21-days LOEC (Reproduction Rate): > 32 mg/L
21-days EC50 (Reproduction Rate):  >32 mg/L
21-days NOEC (Survival of Adults): ≥ 32 mg/L
21-days LOEC (Survival of Adults): > 32 mg/L

Conclusion

The influence of the test item on the survival and reproduction rate of Daphnia magna were determined during an exposure period of 21 days in a dose-response study. The 21-day NOEC values for the reproduction rate and for the survival of the adult test animals were determined to be at least 32 mg test item/L in both cases, i.e. the highest concentration tested.

Description of key information

The influence of the test item on the survival and reproduction rate of Daphnia magna were determined during an exposure period of 21 days in a dose-response study. The 21-day NOEC values for the reproduction rate and for the survival of the adult test animals were determined to be >= 32 mg test item/L in both cases, i.e. the highest concentration tested.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

32 mg/L

Additional information

NOEC >= 32 mg (for freshwater invertebrates)