α,α,α-trifluorotoluene

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2005-05-12 to 2005-06-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Methods of Testing New Chemical Substances (Algae growth inhibition test, Daphnia acute immobilization test, and Fish acute toxicity test) (Yakushokuhatsu No. 1121002, Heisei 15・ 11・13 Seikyoku No. 2, Kampo Kihatsu No. 031121002, 2003)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Remarks:

Gas chromatography-mass spectrometry (GC/MS)

Details on sampling:

The test substance deteriorates by light, therefore, sampling was done under yellow lamp, at the preparation of stock solution. For all test groups, test solution was sampled from one test vessel for analysis.

Vehicle:

no

Details on test solutions:

Stock solution (concentration of 60 mg/L) was prepared by diluting the test chemical with water using ultrasonic treatment (3 minutes). Test chemical was stored at room temperature, darkness and light-interception. IR absorption spectrum of the chemical was measured at the start and the end of the test, and both spectra were not contradictory to each other.

Test organisms (species):

Daphnia magna

Details on test organisms:

- Common name: water flea
- Age at study initiation: less then 24 hours old.
- Supplier/Source: Test organism was obtained from National Institute of Environmental Studies (Japan) and had been reproduced in testing laboratory.
- Pretreatment: Parental daphnids were acclimated for 23 days on test condition before testing. Daphnids were fed with Chlorella vulgaris, 0.2 mg carbon/day/individual. During acclimatization, mortality of parental daphnia was 0 % and resting eggs and males were not shown.
- Feeding during test: none

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

20.0 - 20.4 °C

pH:

8.2 – 8.4

Dissolved oxygen:

60 % above saturation, 8.3 - 8.8 mg/L

Nominal and measured concentrations:

Nominal Concentrations: control, 1.50, 2.70, 4.80, 8.40, and 15.0 mg/L
Time-weighted Mean Concentrations (TWA): control, 0.77, 1.29, 3.11, 5.70 and 9.65 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: beaker
- Type: covered water surface with PTFE sheet to avoid evaporation of test solutions and volatilization of test substance (closed system)
- Material, size, headspace, fill volume: 100 mL glass beaker
- Volume of solution: 100 mL
- Aeration: no
- Renewal rate of test solution: every 24 hours
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 medium

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: 16 h light / 8 h dark
- Light intensity: less than 800 lux

VEHICLE CONTROL PERFORMED: no

RANGE-FINDING STUDY
- Test concentrations: 1st test: 0.577, 5.77, 57.7 mg/L; 2nd test - 2, 5, 12, 30 mg/L
- Results used to determine the conditions for the definitive study: 1st test - 20 % immobilisation at 5.77 mg/L and 100% immobilisation at 57.7 mg/L after 48 h; 2nd test - 10 % immobilisation at 5 mg/L and 100 % immobilisation at 12 and 30 mg/L after 48 h.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

3.11 mg/L

Nominal / measured:

meas. (TWA)

Basis for effect:

mobility

Remarks on result:

other: 95 % CI: 1.29 – 5.70 mg/L

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

1.29 mg/L

Nominal / measured:

meas. (TWA)

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

5.7 mg/L

Nominal / measured:

meas. (TWA)

Basis for effect:

mobility

Details on results:

The ratio of measured concentration to nominal concentration of the test solutions at the test solution preparation was 47 - 73%, and 38 - 66% after 24 hours. The main cause of the decrease was assumed to be due to the volatilization from water.
In the control, the percent immobility during the exposure was 0%, and no trapping daphnids were observed on the water surface, satisfying the criterion for the validity of the test.
The 24-h EC50 was determined to be 3.94 mg/L (95 % CI: 3.11 - 5.70 mg/L).

Results with reference substance (positive control):

The EC50 (48 hr, immobility) for the reference substance was 0.75 mg/L.

Test substance concentration in test solutions

The ratio of measured concentration to nominal concentration was 47 - 73% at the test solution preparation, and 38 - 66% after 24 hours. The main cause of the decrease was assumed to be due to the volatilization from water.

0.1 mL acetone was added to 10 mL of analytical sample (test solutions were diluted by purified water; by two times for 1.50 mg/L group, by five times for 2.70 and 4.80 mg/L groups, by 10 times for 8.40 mg/L group and 20 times for 15.0 mg/L group), mixed and analyzed by using GC/MS.

Table 1. Concentration of the Test Substance in the test medium

Nominal Conc. (mg/L)	Measured Concentration (mg/L) (Percent of Nominal, %)				Time-weighted Mean* Conc. (mg/L)
	0 h (new)	24 h (old)	24 h (new)	48 h (old)
Control	-	-	-	-	-
1.50	0.816 (54)	0.686 (46)	0.826 (55)	0.767 (51)	0.770 (51)
2.70	1.26 (47)	1.02 (38)	1.53 (57)	1.37 (51)	1.29 (48)
4.80	3.35 (70)	2.75 (57)	3.28 (68)	3.08 (64)	3.11 (65)
8.40	5.87 (70)	5.38 (64)	5.98 (71)	5.58 (66)	5.70 (68)
15.0	11.0 (73)	8.98 (60)	10.0 (67)	8.72 (58)	9.65 (64)

* as described in OECD TG 211

 

Table 2. The numbers of Immobile Daphnia magna (Percent Immobility)

Nominal Conc. (mg/L)	Mean Measured Conc. (TWA) (mg/L)	Cumulative Number of Immobilised Daphnia (Percent Immobility, %)
		0hour	48 hours
Control	-	0 (0)	0 (0)
1.50	0.770	0 (0)	0 (0)
2.70	1.29	0 (0)	0 (0)
4.80	3.11	2 (10)	10 (50)
8.40	5.70	20 (100)	20 (100)
15.0	9.65	20 (100)	20 (100)

 

Validity criteria fulfilled:

yes

Conclusions:

The EC50 after 48-h exposure was determined to be 3.11 mg/L.

Executive summary:

In the acute immobilisation test with Daphnia magna, the effects of the test item were determined according to OECD 202. The study was conducted in a semi-static system over a period of 48 hours with a renewal of the test medium after 24 hours. The following concentrations were tested - control, 1.50, 2.70, 4.80, 8.40, and 15.0 mg/L. 20 daphnids per test concentration and control were tested. The test item concentration was determined at the start and at the end of each renewal period GC-MS. As the concentrations differed with more than ± 20 % to the nominal concentration, time-weighted mean (TWA) concentrations were calculated and biological endpoints were based on the TWA concentrations. The validity criteria of the test guideline were fulfilled. Immobilisation of the daphnids was observed in the preliminary tests. After 48-h exposure 50 % immobilization was observed at concentration level 3.11 mg/L and 100 % at 8.40 mg/L. Therefore, the estimated EC50 value (48 hours) of the test item is 3.11 mg/L.

Description of key information

The EC50 after 48-h exposure was determined to be 3.11 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

3.11 mg/L

Additional information

In the acute immobilisation test with Daphnia magna, the effects of the test item were determined according to OECD 202 (reference 6.1.3-1). The study was conducted in a semi-static system over a period of 48 hours with a renewal of the test medium after 24 hours. The following concentrations were tested - control, 1.50, 2.70, 4.80, 8.40, and 15.0 mg/L. 20 daphnids per test concentration and control were tested. The test item concentration was determined at the start and at the end of each renewal period GC-MS. As the concentrations differed with more than ± 20 % to the nominal concentration, time-weighted mean (TWA) concentrations were calculated and biological endpoints were based on the TWA concentrations. The validity criteria of the test guideline were fulfilled. Immobilisation of the daphnids was observed in the preliminary tests. After 48 h exposure 50 % immobilization was observed at concentration level 3.11 mg/L and 100 % at 8.40 mg/L. Therefore, the estimated EC50 value (48 hours) of the test item is 3.11 mg/L.