Methyl (R)-2-(4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy)propionate

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

adult fish: sub(lethal) effects

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 204 (Fish, Prolonged Toxicity Test: 14-day Study)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Haloxyfop-R methyl ester (XRD-535)
Lot #: RMM 2055
Purity: 96.4%

Analytical monitoring:

yes

Details on sampling:

Samples for analysis of the test media were taken on nine occasions during the 28-day exposure duration. On each sampling occasion samples for analysis were taken from both aqueous stock solutions, both the control test media and test media containing test substance, except day 16 when only the two controls and test media containing test substance were analysed.

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

Two solvent stock solutions were prepared by addition of test substance to acetone. The nominal concentrations of the solvent stock solutions were 25 and 0.88 mg/mL. These solvent stock solutions, prepared every seven days of the test and stored in a fridge, were used to prepare two aqueous stock solutions by direct addition to dilution water. The aqueous stock solutions were prepared daily for the duration of the test. The nominal concentrations of the aqueous stock solutions were 2.0 and 0.07 mg/L. The aqueous stock solutions were diluted with water to produce the following nominal concentrations of test substance: 0.7, 0.2, 0.07, 0.02, 0.007 and 0.002 mg/L.

For the solvent control treatment a solvent stock solution was prepared daily by direct addition of 0.8 mL acetone to 10 L dilution water. The stock solution was diluted with water. A further control treatment was prepared with dilution water only.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout
- Strain: Oncorhynchus mykiss
- Source: Fish Network (Upper Hayne Farm, Blackborough, UK),
- Length at study initiation: 6.1 cm (range 6.0-6.5 cm)
- Weight at study initiation: 3.0 g (range 2.5-3.7 g)

Feeding during test
- Food type: Hatchery 800 (BOCM Pauls)
- Amount: At a rate of 2% fresh body weight
- Frequency: Single feed

ACCLIMATION
- Acclimation period: More than 14 days

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

28 d

Hardness:

52.9-56.5 CaCO3 mg/L

Test temperature:

14.5-15.1°C

pH:

6.8-7.4

Dissolved oxygen:

61-100% air saturation

Nominal and measured concentrations:

Nominal: 0 (water control), 0 (solvent control), 0.002, 0.007, 0.02, 0.07, 0.2, 0.7 mg/L
Measured:

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass aquaria
- Size of vessel: 14 L
- Type: Closed
- Material, size, headspace, fill volume: 14 L glass aquaria containing 10 L of test medium
- Aeration: The test vessels were not aerated
- Type of flow-through: Stock solutions and dilution water were delivered continuously to the test vessels using an automated, piston action, syringe dosing apparatus (ADA). The solvent control and control test media were delivered using peristaltic pumps.
- Renewal rate of test solution (frequency/flow rate): 7 complete test medium changes per vessel each day. Flow rate: 50 mL/min
- No. of organisms per vessel: 10
- No. of vessels per concentration: 1
- No. of vessels per control: 1
- No. of vessels per vehicle: 1
- Biomass loading rate: 0.43 g body weight/L (volume in 24 hours)

TEST MEDIUM / WATER PARAMETERS
- Chlorine: 0.01-0.05 mg/L

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light: 8 hours dark

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

0.128 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

mortality

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

0.005 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

other: sub-lethal symptoms

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

> 0.447 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

weight

Remarks on result:

other: highest concentration tested

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

0.043 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

length

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

0.237 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

mortality

Duration:

21 d

Dose descriptor:

LC50

Effect conc.:

> 0.447 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

mortality

Remarks on result:

other: highest concentration tested

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 0.447 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

mortality

Remarks on result:

other: highest concentration tested

Duration:

7 d

Dose descriptor:

LC50

Effect conc.:

> 0.447 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

mortality

Remarks on result:

other: highest concentration tested

Duration:

4 d

Dose descriptor:

LC50

Effect conc.:

> 0.447 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

mortality

Remarks on result:

other: highest concentration tested

Duration:

1 d

Dose descriptor:

LC50

Effect conc.:

> 0.447 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: ester equivalents

Basis for effect:

mortality

Remarks on result:

other: highest concentration tested

Details on results:

- Observed effects at each concentration for each observation time: Mild sub-lethal effects were observed in one fish, on day 21 only in fish exposed to 0.0019 mg/L, by day 22 and subsequently no effects were seen. Mild sub-lethal effects were observed in fish exposed to 0.0135 mg/L from day 4 until day 14, and were seen in fish exposed to 0.0427 mg/L from day 3 and 0.1281 mg/L from day 2 until the end of the test. Mild effects included slightly darkened colouration and apparent loss of appetite and increased 'coughing' frequency. Between two and four of the fish exposed to 0.1281 mg/L exhibited severe toxic effects between days four and ten, some of the remaining fish exhibited mild effects from day 2 and from day 13 all of the fish exhibited mild symptoms until the end of the test.
- Concentrations that produce lethal or other effects: Mild and severe toxic effects were observed at 0.4470 mg/L from day 1, and from day 20 onwards all fish were severely affected until the end of the test. The severe effects demonstrated by the fish at 0.4470 mg/L included loss of appetite and lethargy on day 3, and occasional loss of swimming control on day 4. By day 16 these fish displayed darker colouration than controls and an increased 'coughing' frequency was evident until the end of the test.
- Cumulative mortality at each concentration and for each recommended observation time if possible: On day 4, 10% mortality was observed at the highest concentration of 0.4470 mg/L, increasing to 20% on day 21 and finally 100% by day 28. No mortalities were observed at any other test concentrations.

Reported statistics and error estimates:

The 28-day LC50 value was calculated using probit analysis after log10 transformation. Fresh weight and fork lengths were analysed using analysis of variance and Dunnets test.

Validity criteria fulfilled:

yes

Conclusions:

28-day NOEC (Rainbow trout): 0.1281 mg/L (Mortality)
28-day NOEC (Rainbow trout): 0.0052 mg/L (Sub-lethal symptoms)

Executive summary:

The prolonged toxicity of the test substance to Oncorhynchus mykiss was determined in a 28-day flow-through test with continuous renewal of the test media. The study was carried out in accordance with OECD guideline 204.

Test media were prepared at the following nominal concentrations: 0.7, 0.2, 0.07, 0.02, 0.007 and 0.002 mg/L. Both a solvent control (dilution water and solvent at the same concentration as delivered to the test substance treated vessels, i.e., 0.08 mL per L) and a control (dilution water only) treatment were used. There was one test vessel per treatment containing ten fish, at the start of the exposure phase.

Stock solutions and dilution water were delivered continuously to the test vessels using an automated, piston action, syringe dosing apparatus (ADA). The solvent control and control test media were delivered using peristaltic pumps.

Samples for analysis of the ester and acid hydrolysis product of the test substance were taken on nine occasions during the 28-day exposure duration. Mean measured concentrations were based on the sum of the acid, converted to ester equivalents and ester measured concentrations.

A summary of the mean measured concentrations in the test media (ester plus acid as ester equivalents) are: 0.0019, 0.0052, 0.0135, 0.0427, 0.1281, 0.4470 mg/L.

The toxicity of test substance to O. mykiss was expressed in terms of the mean measured concentrations (sum of acid, converted to ester equivalents and ester components) in the test media.

Mild toxic effects were observed at 0.0135 and 0.0427 mg/L and both mild and severe effects were observed at 0.1281 (transitory severe effects) and 0.4470 mg/L. Mortalities were observed at the highest concentration, 0.4470 mg/L, resulting in 10% mortality after four days and 100% mortality by the end of the 28-day exposure period.

The 28-day LC50 value was 0.2369 mg/L

There were no significant differences between treatments for mean wet weight compared to the solvent control. There were significant differences (P<0.01) between the 0.1281 and 0.4470 mg/L treatments and the solvent control for mean fork length.

Based on mortality, the highest no effect concentration (NOEC) was observed to be 0.1281 mg/L. Based on sub-lethal symptoms, the NOEC was observed to be 0.0052 mg/L. Based on wet weights and forks lengths of surviving fish the NOEC's were calculated to be > 0.4470 mg/L for weight, the highest concentration tested and 0.0427 mg/L for length respectively. Overall, the NOEC is considered to be 0.0052 mg/L.

Description of key information

28-day NOEC (Oncorhynchus mykiss, Rainbow trout): 0.0052 mg/L (Sub-lethal symptoms); OECD 204, Reliability = 1

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

0.005 mg/L