Methenamine

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1976

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non GLP Report, no analytical concentration confirmation

Qualifier:

according to guideline

Guideline:

other: U.S. EPA, 1975: Methods for Acute Toxicity Tests with Fish, Macroinvertebrates and Amphibians (EPA-660/3-75-00 p. 61)

Deviations:

not specified

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
unlimited soluble in water.

Analytical monitoring:

no

Details on sampling:

no sampling

Vehicle:

no

Details on test solutions:

Individual treatment levels were prepared by weighing out separate amounts of the test material and introducing them directly into the test vessels, thoroughly mixing the toxicant and dilution water.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: Bluegill sunfish
- Strain: Rafinesque
- Source: Nebraska
- Age at study initiation: about 4 months
- Length at study initiation: 28 mm
- Weight at study initiation: 0.48 g

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

no post exposure period

Hardness:

43 mg/L as CaCO3

Test temperature:

22.0 +/- 1.0 °C

pH:

7.62

Dissolved oxygen:

control: 7-11 mg/L O2

Salinity:

conductivity: 164 µmhos/cm

Nominal and measured concentrations:

Nominal concentrations: 0; 10; 18; 32; 56; 100 g/L

Details on test conditions:

The test vessels were 5 gallon glass jars containing 15 liters of water. Ten organisms were exposed to each treatment. The loading was 0.32 g/L.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

41 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 32-53 g/L

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

18 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

Behavioral observations made during the test indicated that bluegill sunfish exposed to concentrations of methenamine greater than 18 g/L became lethargic and showed signs of labored respiration.

Results with reference substance (positive control):

no reference substance used.

Reported statistics and error estimates:

The LD50 and their accompanying slope values with 95 % confidence intervals were determined by the Litchfield-Wilcoxin method (1949).

Validity criteria fulfilled:

yes

Conclusions:

The LD50 of methenamine in bluegill sunfish was determined to be 41 g/L.

Executive summary:

In a 96-h acute toxicity study, Bluegill Sunfish (Lepomis macrochirus) were exposed to methenamine at nominal concentrations of 0; 10; 18; 32; 56; 100 g/L under static conditions. The 96-h LC50 was 41 mg/L. Sublethal effects of labored respiration were observed in the groups exposed over 18 mg/L of methenamine. This toxicity study is classified as acceptable and satisfies the guideline requirement for acute toxicity to fish study.

Results Synopsis

Test organism size/age: 28 mm / 4 months

Test Type: Static

LC50: 41 g/L (95% C.I.: 32 to 53 g/L)

NOEC: 18 g/L

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: non GLP, no guideline, no analytic concentration confirmation

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

not specified

GLP compliance:

not specified

Analytical monitoring:

not specified

Details on sampling:

not indicated

Vehicle:

not specified

Details on test solutions:

not indicated

Test organisms (species):

Cyprinodon variegatus

Details on test organisms:

Collected from Galveston Bay

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

not indicated

Hardness:

174 mg/l as CaCO3

Test temperature:

not indicated

pH:

pH 7.7

Dissolved oxygen:

not indicated

Salinity:

20.5 ‰

Nominal and measured concentrations:

nominal: 30 and 60 g methenamine/L

Details on test conditions:

5 fish per concentration.

Reference substance (positive control):

not specified

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

49 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 35.9 - 66.9 g/L

Details on results:

not indicated

Results with reference substance (positive control):

not indicated

Reported statistics and error estimates:

Probit Analysis

Validity criteria fulfilled:

yes

Conclusions:

LC50 (cyprinodon variegatus) = 49 g/L

Executive summary:

Walton and Davis examined the impact of 30 and 60 g methenamine/l on Cyprinodon variegatus. The static test was conducted in brackish water (salinity 20.5 ‰, pH 7.7, alkalinity 174 mg/l as CaCO3). A (nominal) 96 h LC50 of 49 g/l was reported.

Description of key information

The LC50 of methenamine in bluegill sunfish (freshwater) was determined to be 41 g/L. The LC50 of methenamine in cyprinodon variegatus(saltwater) was determined to be 49 g/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

41 000 mg/L

Marine water fish

Marine water fish

Dose descriptor:

LC50

Effect concentration:

49 000 mg/L

Additional information

Key studies:

- In a 96-h acute toxicity study (Kuc, 1980), Bluegill Sunfish (Lepomis macrochirus, Freshwater) were exposed to methenamine at nominal concentrations of 0; 10; 18; 32; 56; 100 g/L under static conditions. The 96-h LC50 was 41 mg/L. Sublethal effects of labored respiration were observed in the groups exposed over 18 mg/L of methenamine. This toxicity study is classified as acceptable and satisfies the guideline requirement for acute toxicity to fish study.

- Walton and Davis (1980) examined the impact of 30 and 60 g methenamine/l on Cyprinodon variegatus (saltwater). The static test was conducted in brackish water (salinity 20.5 ‰, pH 7.7, alkalinity 174 mg/l as CaCO3). A (nominal) 96 h LC50 of 49 g/l was reported.

Supporting studies:

- In a 96-h acute toxicity study (Linden, 1979), bleak (Alburnus alburnus) were exposed to methenamine at nominal concentrations (6 doses and one control were used) under static conditions. The 96-h LC50 was > 10000 mg /L. This toxicity study is classified as acceptable and satisfies the guideline requirement for acute toxicity to fish studies.

- In a 24-h acute toxicity study (Mac Phec, 1969), Northern squawfish (Ptychocheilus oregonensis), Chinnok salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch) were exposed to methenamine at a nominal concentrations of 10 ppm under static conditions. The 24-h LC50 for all 3 species tested was > 10 ppm. No mortality and no signs of lost equilibrium occurred for all 3 species tested in this 24 h assay.

This toxicity study is classified as acceptable as supporting study.

- A flow-through test with juveniles of Pimephales promelas (aged 33 d) was carried out in lake water (pH 7.8, hardness 44.9 mg/l as CaCO3). The LC50 (96 h) based on measured concentrations was 49.8 g/l (Geiger et al. 1988).

Based on the available data, no toxicity towords several fresh and saltwater fish species even at concentrations > 10000 mg/L, which by far exceeded the recommended limit concentration of OECD guidelines (100 mg/L) clearly indicate, that methenamine is not toxic at all towords saltwater or freshwater fish.