Propanoic acid, 2-(4-chloro-2-methylphenoxy)-, 2-ethylhexyl ester, (2R)-

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adult fish: sub(lethal) effects

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 0993-04-07 to 1993-09-20

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1984; prolonged to 28 days

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: German Federal Environmental Protection Agency I 4.5-97125-2/6: Test guideline "Sublethal toxic effects in the zebrafish Brachydanio rerio" (threshold level of the lethal and other effects; NOEC; at least 14 days)

Version / remarks:

issued 1982, considering the updated version of Feb. 1, 1984

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch: 91-1
Purity: 92.7%

Analytical monitoring:

yes

Details on sampling:

- Concentration controls: Samples were taken on day zero and then at weekly intervals from the test aquaria and were analyzed for content of test compound.
- Stability: The stability of MCPP-P acid in water was verified by the analytical concentration control. The samples for the weekly concentration controls during the study had generally always been taken out of the aquaria immediately before the stock dilutions in the storage vessels were replaced except at the beginning of the study.

Vehicle:

no

Details on test solutions:

- Stock solution preparation: Since the acid is hardly soluble in water, a concentrated stock solution was prepared by dissolving the aliquot amount of the test compound in water by adding an aliquot quantity of NaOH (about 10 %). This mixture was then stirred on a magnetic stirrer until the test compound was completely dissolved. Thus, the water soluble sodium salt was prepared. This concentrated stock solution was then used to prepare all stock solutions for the test groups.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout
- Bionomial name: Oncorhynchus mykiss Walbaum 1792
- Source: Forellenhof Fredelsloh Trout Breeding, D-37186 Moringen, Germany
- Hatched: 1992-11
- Length at study initiation (average): 6 (5.4 - 6.7) cm
- Weight at study initiation (average): 1.9 (1.5 - 2.5) g
- Sex: At that juvenile age the sex cannot be reliably determined by a visual inspection. Therefore the animals were used in an unspecified sex ratio.

Feeding during test
- Food type: "Ssniff" trout starter FB-50/size 1, of "Ssniff", Soest, Germany
- Amount and frequency: about 4% of their mean body weight on workdays daily in 2 portions and on non-working days in one portion. Beginning with week 2 of the study the amount of feed was generally increased by 25%-each week

ACCLIMATION
- Acclimation period: from arrival in the laboratory to test initiation - ca. three months
- Acclimation conditions: similar to study conditions
- Type and amount of food: "Ssniff" trout starter FB-50/size 1, of "Ssniff", Soest, Germany
- Feeding frequency during acclimation: about 1 to 2 % of their mean body weight daily in 2 portions on workdays and in one portion on non-working days; additionally they received on workdays artemia during the initial 2 weeks
- Health during acclimation (any mortality observed): no mortality obsered up to one week before test start

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

28 d

Hardness:

ca. 2.3 mmol/L

Test temperature:

16 °C

pH:

8.3 - 8.5

Dissolved oxygen:

9.1 - 10.3 mg/L

Salinity:

NA

Conductivity:

no data

Nominal and measured concentrations:

Nominal concentration: 0, 1, 10, 50 and 100 mg/L
The measured concentrations were in the range 88.8 - 105.1 % with an average of 96 %.

Details on test conditions:

TEST SYSTEM
- Test vessel: aquarium
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass in a stainless steel frame, 60 x 35 x 40 cm, 60 L water
- Aeration: The aquaria were aerated continuously with oil-free air.
- Type of flow-through: The mixture of dilution water and a stock dilution of the test substance flows continuously into the test aquaria via a mixing tank.
- Renewal rate of test solution: 6 h/tank water exchange with a flow rate of 10 L/hour/test aquarium
- No. of organisms per vessel: 20

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Drinking water from the city of Frankenthal, purified over active carbon and aerated
- Total hardness: about 2.3 mmol/L
- pH: about 8.3 - 8.5

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light/8 hours darkness

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

No mortality occured in any test group. Signs or symtoms of toxicity were only observed at the highest concentration of 100 mg/L where slight discoloration was observed on day 2 and 5 of the study. Compared with the control group at the end of the study, the mean body weight at 100 mg/L was statistically significant smaller (<=0.05) and the mean body length at 100 mg/L was statistically significant smaller (<=0.01).

Mortality

No mortality occurred both in the controls and in all test concentrations. The lowest concentration at which mortalities occurred was greater than 100 mg/L. The threshold level of lethal effects was greater than 100 mg/L. The highest concentration tested without mortalities was 100 mg/L.

Toxic signs

No marked toxic signs were observed in all groups that contained test compound. Only in the highest test group (100 mg/L) a slight discoloration was seen on days 2 and 5 of the study. The threshold level for toxic signs (= symptoms) was about 100 mg/L. The "No Observed Effect Concentration" (NOEC) for toxic signs (= symptoms) was 50 mg/L.

Body weight

At the beginning (day 0), the mean body weights for all groups including control ranged from 1.9 - 2.0 g. At the end of the study (day 28) the mean body weight of the control group was 6.6 g and those of the concentration groups 1; 10; 50 and 100 mg/L were 6.5; 6.7; 6.4 and 5.9 g which is an increase of about factors 2.9 to 3.5 compared to the initial weight. The weight gain in the highest test group was statistically significantly reduced at the p ≤ 0.05 level compared to the control group. Thus, under the conditions of this study, the no effect concentration for the impairment of the body weight was 50 mg/L.

Body length

At the beginning of the study (day 0), the mean body length for all groups including the control group ranged from 6.0 - 6.1 cm. At the end of the study (day 28), the mean body length of the control group was 8.6 cm and those of the test groups with the concentrations 1; 10; 50 and 100 mg/L were 8.6; 8.7; 8.4 and 8.0 cm which is an increase of about factors 1.3 to 1.4 compared to the initial length. The gain in body length in the highest test group was statistically significantly reduced at the p ≤ 0.01 level compared to the control group. Thus, under the conditions of this study, the no effect concentration for the impairment of the body length was 50 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

For MCPP-P acid, the hydrolysis product of MCPP-P 2-EHE, a 28 d-NOEC of 50 mg/L was determined.

Executive summary:

MCPP-P 2-EHE hydrolyses rapidly in natural water. Therefore, the main hydrolysis product MCPP-P acid was used for further assessment of MCPP-P 2-EHE with respect to long-term toxicity to fish.

 

In a prolonged toxicity test in a flow-through system according to the OECD Guideline 204 the long-term toxicity of MCPP-P acid on Oncorhynchus mykiss was determined. Under the conditions of this study the overall NOEC was determined to be 50 mg/L for the rainbow trout (nominal concentration). The threshold level for lethal effects was greater than 100 mg/L, for toxic signs (= symptoms) about 100 mg/L and for the growth parameters body weight plus length >50 and <100 mg/L (nominal concentrations).

Reference 2

Endpoint:

adult fish: sub(lethal) effects

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to section 13 for "Read Across justification".

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Description of key information

For MCPP-P acid, the hydrolysis product of MCPP-P 2-EHE, a 28 d-NOEC of 50 mg/L was determined.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

50 mg/L

Additional information

The long-term toxicity to fish was investigated with MCPP-P acid, as the acid is the main hydrolysis product of MCPP-P 2-EHE (read-across).

 

In a prolonged toxicity test in a flow-through system according to the OECD Guideline 204 the long-term toxicity of MCPP-P acid on Oncorhynchus mykiss was determined. Under the conditions of this study the overall NOEC was determined to be 50 mg/L for the rainbow trout (nominal concentration). The threshold level for lethal effects was greater than 100 mg/L, for toxic signs (= symptoms) about 100 mg/L and for the growth parameters body weight plus length >50 and <100 mg/L (nominal concentrations).