tert-butyl 3,5,5-trimethylperoxyhexanoate

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:

1992-10-23 to 1993-06-29

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

1984

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Version / remarks:

1984

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

Each test dilution was prepared from an aqueous stock solution (2 L) in which an appropriate weight of test material, mixed with acetone, was added to the dilution water: it was treated by ultrasound (10 minutes) to aid dispersion before use.

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 Limited, Devon
- Length at study initiation (length definition, mean, range and SD): 4.3 cm
- Weight at study initiation (mean and range, SD): 1.0 g
- Feeding during test
- Food type: proprietary trout pellets (BP Nutrition Ltd., Mainstream Trout Fry 02)
- Amount: amount equivalent to approximately between 1 and 4 % of the total wet-weight of the fish in the holding tank.
- Frequency: each day during the holding period

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

c (CaCO3): 244 to 246 mg/L

Test temperature:

14.7 ± 0.6 °C

pH:

pH: 7.4 to 8.0

Nominal and measured concentrations:

nominal concentrations: 0.75, 1.5, 3, 6, 12 and 24 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, fill volume: The test vessels were all-glass aquaria, with a total capacity of 15 litres. The depth of the test solutions in these vessels was approximately 14.5 cm. Aeration of the contents of each vessel was achieved using a Pasteur pipette connected to an oil-free supply of compressed air.

TEST MEDIUM / WATER PARAMETERS
Monitoring water quality during the 14-day holding period immediately preceding the definitive test showed the following:
- temperatures ranged from 12.2 to 14.2 °C
- pH values ranged from 7.8 to 8.0
- dissolved oxygen concentrations (DO) ranged from 96 to 100% air saturation value (ASV)
- water hardness ranged from 244 to 250 mg/L as CaCO3

OTHER TEST CONDITIONS
The study was carried out in a temperature-controlled area nominally at 15 ± 2 °C. The day length in the test area was controlled giving a photoperiod of 16 hours light, supplied by overhead fluorescent tubes, and eight hours darkness. Dawn and dusk were simulated by periods of subdued lighting at the beginning and end of each light phase.

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

14.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 12%

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

14.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 24%

Duration:

72 h

Dose descriptor:

LC50

Effect conc.:

7.03 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 6%

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

7.03 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 12%

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Results with reference substance (positive control):

No positive control

Reported statistics and error estimates:

Statistical analysis:
Median lethal concentrations (LC50s) were estimated by the computer program of Stephan using the number of fish exposed and the number dead at each nominal Trigonox 42S concentration.

Sublethal observations / clinical signs:

Cumulative mortality:

	Nominal Trigonox 42S concentrations, mg/L
Observation times (hours)	0	0*	0.75	1.5	3	6	12	24
2	0	0	0	0	0	0	0	0
4	0	0	0	0	0	0	2	3
24	0	0	0	0	0	0	3	10
48	0	0	0	0	0	0	3	10
72	0	0	0	0	0	3	10	10
96	0	0	0	0	0	3	10	10

Validity criteria fulfilled:

yes

Conclusions:

The acute lethal toxicity of tert-Butylperoxy-3,5,5-trimethylhexanoat to the rainbow trout was assessed over a period of 96 hours: a semi-static exposure regime was employed with renewal of control and test media after 48 hours.
The highest nominal concentration at which no mortalities occurred and the lowest at which there was 100% mortality after 96 hours was 3 and 12 mg/L respectively.
Treatment-related effects, which were seen at and above 6 mg/l, included darkened pigmentation, lethargic behaviour and loss of coordination. At 12 and 24 mg/L all fish were affected after exposure to the test material for 24 hours and were all dead by 27 and 48 hours respectively. At 6 mg/L, two fish were affected at 24 and 48 hours: at 72 hours three had died and a further three were affected.
The no-observed-effect concentration (NOEC) was therefore 3 mg/L.

Executive summary:

Tert-Butylperoxy-3,5,5-trimethylhexanoat was tested in an acute toxicity test with the rainbow trout under semi-static conditions in accordance with EEC method C.1 (1984) and OECD Test Guideline 203 (1984).

No chemical analysis of control and test media was undertaken.

Groups of ten fish were exposed to tert-Butylperoxy-3,5,5-trimethylhexanoat at nominal concentrations of 0.75, 1.5, 3, 6, 12 and 24 mg/L, selected

following a preliminary, range finding test. Each test dilution was individually prepared by adding the test material to dilution water: acetone and sonication were used to aid dispersion. Control groups of fish were placed in dilution water alone or dilution water containing acetone at the same level as in the test dilutions (0.1 mL/L).

The test was conducted at 14.7 ±0.6°C in treated tap water of hardness 244 to 246 mg/L as CaCO3 at pH values in the range 7.4 to 8.0. The test media were colourless with undissolved material visible on their surfaces; the amount of material increased with increasing concentration.

Observations of the fish were made at least at 24 -hour intervals.

The highest nominal concentration at which no mortalities occurred and the lowest at which there was 100% mortality after 96 hours was 3 and 12 mg/L respectively.

Treatment-related effects, which were seen at and above 6 mg/L, included darkened pigmentation, lethargic behaviour and loss of coordination. At 12 and 24 mg/L all fish were affected after exposure to the test material for 24 hours and were all dead by 27 and 48 hours respectively. At 6 mg/l, two fish were affected at 24 and 48 hours: at 72 hours three had died and a further three were affected.

The no-observed-effect concentration (NOEC) was therefore 3 mg/L.

Median lethal concentrations (LC50s), calculated at intervals during the test using nominal exposure concentrations, are listed below.

Observation intervals (hours)	Approximate LC50s mg/L
24 & 48	14.1 (12 & 24)
72 & 96	7.03 (6 & 12)

( ) : concentration used to calculate the LC50.

Since mortality was progressive during the test, an asymptotic LC50 may not have been attained.       

Description of key information

tert-Butylperoxy-3,5,5-trimethylhexanoat was tested for acute toxicity to fish to EU-method C.1 (1984) and OECD guideline 203 (1984). In this 96-hour semi-static acute toxicity test with rainbow trout, the LC50 value was 7.03 mg/L. The no-observed-effect concentration (NOEC) was 3 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

7.03 mg/L

Additional information

tert-Butylperoxy-3,5,5-trimethylhexanoat was assessed in short-term toxicity to fish study, according to EU method C.1 and OECD guideline 203.

Fish (rainbow trout) were exposed in a semi-static test to the test item for 96 hours at nominal concentrations of 0.75, 1.5, 3, 6, 12 and 24 mg/L. The LC50 values was 7.03 mg/L. The no-observed-effect concentration (NOEC) was therefore 3 mg/L.