Metformin hydrochloride

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 29 - July 3, 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: FDA TAD 4.11

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 95.3, 171, 309. 555, and 1000 mg/L
- Sampling method: Analytical samples were taken at 0, 48, and 96-hours of the toxicity test.
- Sample storage conditions before analysis: in a refrigerator at - 4°C

Vehicle:

no

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: Bluegill (Lepomis macrochirus)
- Source: Osage Catfisheries Osage Beach, Missouri
- Age at study initiation (mean and range, SD):
- Length at study initiation (length definition, mean, range and SD): Mean ± SD Standard Length: 26 ± 1 mm, Standard Length Range 23 - 28 mm
- Weight at study initiation (mean and range, SD): Mean ± SD Wet Weight: 0.37 ± 0.06 g
- Method of breeding: NA
- Maintenance of the brood fish: NA

ACCLIMATION
- Acclimation period: The fish were held in well water approximately 3 weeks then transferred to hard blended dilution water for 8 days prior to the test. A sublot of bluegill was acclimated to the test temperature and test dilution water for approximately 72 hours prior to the definitive test.
- Acclimation conditions (same as test or not): The culture room was maintained on a 16-hour daylight photoperiod with a 30-minute transition period.
- Type and amount of food during acclimation: The fish were fed newly hatched brine shrimp nauplii (Anemia sp.) and/or a commercially available fish food once or twice per day.
- Health during acclimation (any mortality observed): NA

FEEDING DURING TEST : No

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

144 to 158 mg/L as CaCO3

Test temperature:

22 (± 1)°C

pH:

7.9 to 8.4

Dissolved oxygen:

5.3 to 8.4 mg/L

Nominal and measured concentrations:

nominal: 95.3, 171, 309. 555, and 1000 mg/L
measured: 95.5, 170, 300, 555, and 982 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 5-gallon glass vessels
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 15 L
- Aeration: No
- Type of flow-through (e.g. peristaltic or proportional diluter): NA
- Renewal rate of test solution (frequency/flow rate): NA
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): NA
- Biomass loading rate: NA

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The water was prepared by blending naturally hard well water with well water that had been demineralized by reverse osmosis. This blended water was prepared to yield a total hardness of 130-160 mg/L as CaCO3.
- Total organic carbon: <1.0 mg/L
- Particulate matter: NA
- Metals: NA
- Pesticides: NA
- Chlorine: NA
- Alkalinity: 160 mg/L (as CaCO3)
- Ca/mg ratio: NA
- Culture medium different from test medium: No
- Intervals of water quality measurement: Total alkalinity and hardness (mg/L as CaCO3) were measured in all test chambers at 0 and 96 hours. Temperature (°C). dissolved oxygen (mg/L), and pH were measured in all test chambers at 0, 24, 48, 72, and 96 hours of testing.

OTHER TEST CONDITIONS
- Adjustment of pH: NA
- Photoperiod: The test was on a 16-hour daylight photoperiod with a 30-minute transition period.
- Light intensity: Light intensity measured during the test was 59 footcandles (635 lux).

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Lethality

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline: NA
- Range finding study : A range-finding test of 96 hours duration was conducted to determine the concentration range for the definitive study. The preliminary test concentrations were set at 0.10, 0.32, 1.0, 3.2, 10, 32, and 100 mg/L. Each concentration consisted of a single replicate with 10 fish per chamber. The test solutions at every level remained clear and free of precipitate for the duration of the study. There were no mortality or abnormal effects noted in any test chamber.
- Test concentrations: 95.3, 171, 309, 555, and 1000 mg/L:

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 982 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

982 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks:

and other abnormal effects

Details on results:

The 96-hour LCso was determined to be > 982 mg/L based on the mean measured concentrations of metformin HCI. The 96-hour no-observed effect concentration (NOEC) was 982 mg/L, which was based on the lack of mortality and abnormal effects at this concentration.

Validity criteria fulfilled:

yes

Conclusions:

The 96-hour LCso was determined to be > 982 mg/L based on the mean measured concentrations of metformin HCI. The 96-hour no-observed effect concentration (NOEC) was 982 mg/L, which was based on the lack of mortality and abnormal effects at this concentration.

Executive summary:

Study design

The 96-hour toxicity of metformin HCl to freshwater fish was studied with bluegill (Lepomis macrochirus) in a static test according to FDA TAD 4.11.
A total of 20 fish per concentration was exposed. The study was conducted at test material concentrations of 95.3, 171, 309, 555, and 1000 mg/L. The test concentrations were analytically quantified from samples collected at 0, 48 and 96 hours.

Results

The 3-, 6-, 12-, 24-, 48-, 72-, and 96-hour LC₅₀values for metformin HCI were all > 982 mg/L. All results were based on the measured concentrations of 95.5, 170, 300, 555, and 982 mg/L. The 96-hour no­observed-effect concentration (NOEC) was 982 mg/L, based on the lack of mortality or observed abnormal/sublethal effects at this concentration.

Conclusion

The 96-hour LCso was determined to be > 982 mg/L based on the mean measured concentrations of metformin HCI. The 96-hour no-observed effect concentration (NOEC) was 982 mg/L, which was based on the lack of mortality and abnormal effects at this concentration.

Description of key information

The 96-hour LC50 was determined to be > 982 mg/L based on the mean measured concentrations of metformin HCI. The 96-hour no-observed effect concentration (NOEC) was 982 mg/L, which was based on the lack of mortality and abnormal effects at this concentration.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

982 mg/L

Additional information

The 96-hour LC50 was determined to be > 982 mg/L.