4-Ethoxy-4'-ethyl-2,3-difluoro-1,1'-biphenyl

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:

Dec 30, 2015 - Jun 15, 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The study was conducted for a registration a non-EU country.

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

Principles of method if other than guideline:

none

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

at 0, 24, 48, 72, and 96 h

Vehicle:

no

Details on test solutions:

Dechlorinated drinking water sterilized by UV lamp is used in the test.

Test organisms (species):

other: Gobiocypris rarus

Details on test organisms:

The test was performed with Gobiocypris rarus which were obtained from the Institute of Hydrobiology, Chinese Academy of Sciences (ID: GR-IHB-150306). This freshwater fish species is suitable for fish toxicity testing because of their ease of culturing and handling, sensitivity to a variety of chemical substances, and the extensive data base for this species. This species complies with Ministry of environmental protection of the people's Republic of China, The Guidelines for the Testing of Chemicals-Effects on Biotic System, 2013, 203 Fish, Acute Toxicity Test, OECD, Guidelines for the Testing of Chemicals. 203 Fish, Acute Toxicity Test, 1992 and GB/T 29763-2013 Chemicals-Rare Minnow (Gobiocypris rarus) acute toxicity test.

For evaluation of the fish quality and experimental conditions, potassium dichromate was tested as a positive control to demonstrate satisfactory test conditions once a year(recently performed on 2015.7.7-7.11). The 96h LC50 value of the test substance to Gobiocypris rarus was 153 mg/L (95% confidence limits: 119-195mg/L), which was within the ± 2SD range of the QC chart in our lab(81.6-307mg/L).

Photoperiod: Light/Dark= 12 hours/12 hours;
Feeding: fish were fed with brine shrimp flake (O.S.I®, USA) daily until 24 hours before the test was started.
Length was 2.6 ± 0.1 cm (Mean ± SD) and weight was 0.27±0.039 (Mean ± SD) at the end of the test.
No diseases were observed during the acclimation period;
No mortality was present within the 7 days before the start of the test.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Remarks on exposure duration:

renewal every 24 h

Test temperature:

22.3 - 22.9 °C

pH:

7.81 to 8.26

Dissolved oxygen:

65.2 - 90.1 %

Nominal and measured concentrations:

loading rate of 100 mg/L (mean measured concentration < LOD2, LOD2=0.0636mg/L)

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 0.064 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

not determinable

Remarks:

LC 50 was above solubility limit

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.064 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: solubility limit in test solution

Details on results:

The test results showed that the 96h LC50 for the test substance to Gobiocypris raruswas higher than the concentration of the saturated solution (which time-weighted mean measured concentration was
0.0636 mg/L) under tested conditions.

- Mortality of control: none
- Abnormal responses: none

Results with reference substance (positive control):

For evaluation of the fish quality and experimental conditions, potassium dichromate was tested as a positive control to demonstrate satisfactory test conditions once a year (recently performed on 2015.7.7-7.11). The 96h LC50 value of the test substance to Gobiocypris rarus was 153mg/L (95% confidence limits: 119-195mg/L), which was within the ± 2SD range of the QC chart in our lab (81.6-307mg/L).

Validity criteria fulfilled:

yes

Conclusions:

Based on these results, the test substance has no acute toxicity effect on Gobiocypris rarus under the present conditions of the test.

Executive summary:

The study was conducted according to OECD Guideline 203. A nominal concentration of 100 mg/L of the test substance was prepared and stirred (via magnetic stirrer) in the dark for 72h at 500 rpm followed by filtration using a 0.45μm nitrocellulose membrane to make a saturated solution of the test substance in the test water (referred to as "saturated solution" in this report). Based on the results of the range-finding test, the saturated solution was used to perform the limit test with a blank control. The test duration was 96h and the frequency of renewal was every 24h.

There were no mortalities and abnormalities observed in treatment group during the test period. No mortality occurred in the control during the test and the dissolved oxygen concentration was greater than 60.0% of the air saturation value (ASV) throughout the test duration. Hence, the test was considered to be valid.

During the limit test, the measured concentrations of the test substance in the newly prepared test solutions ranged from 72.8 -78.4 μg/L and thus below the limit of quantification of 159 μg/L. The test material concentrations in the aged media before the renewal were below the limit of detection of 63.6 μg/L. There was no acute toxicity of the saturated solution in the limit test. The 96h LC50 for the test substance to Gobiocypris rarus was higher than the concentration of the saturated solution (the time-weighted mean measured concentration was 0.0636 mg/L) under tested conditions.

Based on these results, the test substance has no acute toxicity effect on Gobiocypris rarus under the present conditions of the test.

Description of key information

The informtion for this endpoint study record was obtained from an experimental study. The OECD GLP criteria were met and the methods applied are fully compliant with OECD TG 203. This study showed no toxicity at the solubility limit of the test material. The 96h LC50 for the test substance to Gobiocypris rarus was higher than the concentration of the saturated solution (the time-weighted mean measured concentration was 0.0636 mg/L) under tested conditions.

Additional information

The study was conducted according to OECD Guideline 203.A nominal concentration of 100 mg/L of the test substance was prepared and stirred (via magnetic stirrer) in the dark for 72h at 500 rpm followed by filtration using a 0.45μm nitrocellulose membrane to make a saturated solution of the test substance in the test water (referred to as "saturated solution" in this report). Based on the results of the range-finding test, the saturated solution was used to perform the limit test with a blank control. The test duration was 96h and the frequency of renewal was every 24h.

There were no mortalities and abnormalities observed in treatment group during the test period. No mortality occurred in the control during the test and the dissolved oxygen concentration was greater than 60.0% of the air saturation value (ASV) throughout the test duration. Hence, the test was considered to be valid.

During the limit test, the measured concentrations of the test substance in the newly prepared test solutions ranged from 72.8 -78.4μg/L and thus below the limit of quantification of 159μg/L. The test material concentrations in the aged media before the renewal were below the limit of detection of 63.6μg/L. There was no acute toxicity of the saturated solution in the limit test. The 96h LC50 for the test substance to Gobiocypris rarus was higher than the concentration of the saturated solution (the time-weighted mean measured concentration was0.0636mg/L) under tested conditions.

Based on these results, the test substance has no acute toxicity effect on Gobiocypris rarus under the present conditions of the test.