Di-tert-pentyl peroxide

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:

June 2016 - January 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

yes

Remarks:

The deviations were not considered to have affected the outcome or the achievement of the study objectives.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Storage of sample : None
Samples treatment : Dilution with acetonitrile

Vehicle:

no

Details on test solutions:

A test medium is saturated with the test item by slow stir method: 1.46mL of test item are gently dropped on the surface of 6000mL of test medium. The saturated solution is obtained after 65 hours of slow stirring.
The different concentrations are prepared by dilution of the saturated solution with test medium.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

Holding was maintained within the laboratory at a temperature of 21-25°C in glass tanks. A light cycle of 12 h light and 12 h dark was applied, illumination being provided by fluorescent tubes (intensity between 400 and 800 lux at the surface of the tanks). Tanks were aerated to ensure that the dissolved oxygen concentration is at least 60% of air saturation value in holding tanks and in test tanks. During holding, fish were fed twice per day with ground flake food TetraMin®.
The fish were not fed for a period of 24h prior to test commencement nor throughout the duration of the test.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

250 mg CaCO3/L

Test temperature:

mean of 23.3°C, min.: 22.6°C, max.: 23.6°C.

pH:

see 'Any other information on results incl. tables.'

Dissolved oxygen:

see 'Any other information on results incl. tables.'

Salinity:

Not relevant

Nominal and measured concentrations:

Definitive test : series of dilution of saturated solution : 3.8, 6.9, 12.5, 22.4, 40.4 and 72.7% corresponding to the measured concentrations : 0.21, 0.41, 0.55, 1.28, 2.89, 5.52 mg/L

Details on test conditions:

Fish were exposed to a series of dilutions (3.8, 6.9, 12.5, 22.4, 40.4 and 72.7%) of a saturated stock solution in dilution water. One tank was prepared at each test concentration; each tank contained 7 fish.
Test solutions were renewed every day throughout the 96h test period (semi-static test). A new test item stock solution was prepared as described before except that the stock solutions for renewal were prepared daily and stirred for at least 72 hours.
The pH of the test solutions were not adjusted.

pH and dissolved oxygen concentrations were measured for all tanks at the beginning of the definitive test and thereafter at 24h intervals. The total hardness of a sample of the medium used to prepare the test solutions was measured and expressed as mg CaCO3/L.
The temperature was continuously recorded in one tank.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

2.89 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

The 96h-LC50 could not be statically determined by the program using the default template for the OECD 203 guideline due to the mortality reported at the smallest test concentration (i.e. 0.21 mg/L). This observed mortality is not considered to be treatment-related as no deaths have been observed at 0.41, 0.55, 1.28 and 2.89 mg/L. Nevertheless, the 96h-LC50 is estimated to be between 2.89 and 5.52 mg/L based on observed biological effects.
The worst case value is retained for risk assessment and classification.

Sublethal observations / clinical signs:

The details of the cumulative lethality are presented in the table below:

CUMULATIVE LETHALITY(DEFINITIVE TEST)

 

Test solution (% saturated stock solution)		Cumulative dead fish				Mortality at the end of the period
	T+2h	T24h	T48h	T72h	T96h
Control	0	0	0	0	0	0.0%
3.8	0	0	0	1*	1	14.3%
6.9	0	0	0	0	0	0.0%
12.5	0	0	0	0	0	0.0%
22.4	0	0	0	0	0	0.0%
40.4	0	0	0	0	0	0.0%
72.7	0	0	4	4	4	57.1%

*in view of the absence of mortality at all other tested concentrations (except at the highest) this mortality could be considered as incidental.

Validity criteria fulfilled:

yes

Conclusions:

The 96h-LC50 could not be statically determined by the program using the default template for the OECD 203 guideline due to the mortality reported at the smallest test concentration (i.e. 0.21 mg/L). This observed mortality is not considered to be treatment-related as no death have been observed at 0.41, 0.55, 1.28 and 2.89 mg/L. Nevertheless, the 96h-LC50 is estimated to be between 2.89 and 5.52 mg/L based on observed biological effects.
The worst case value is retained for risk assessment and classification purpose.

Executive summary:

This study was designed to determine the effects of the test item to Danio rerio over a 96h period with semi-static conditions, according to the OECD 203 Guideline.

As the test item was known to be difficult to dissolve in water (due to its chemical nature), saturated stock solutions were prepared using slow-stirring conditions described in the OECD 123 guideline.

A low toxicity of the test item was expected, the preliminary test was thus carried out as a limit test with semi-static conditions. However, the results of this preliminary test showed an unexpected toxicity on fish (100% mortality at 48h). Consequently, a dose-response definitive test with semi-static conditions was conducted. Fish were exposed to a series of dilutions (3.8, 6.9, 12.5, 22.4, 40.4 and 72.7%) of a saturated stock solution in dilution water.

The chemical analysis of the test item throughout preliminary and definitive tests showed an instability of the substance. Consequently, geometric means of measured concentrations were used to determine 96h-EC10 and 96h-LC50.

The 96h-LC50 could not be statically determined by the program using the default template for the OECD 203 guideline due to the mortality reported at the smallest test concentration (i.e. 0.21 mg/L). This observed mortality is not considered to be treatment-related as no deaths have been observed at 0.41, 0.55, 1.28 and 2.89 mg/L. Nevertheless, the 96h-LC50 is estimated to be between 2.89 and 5.52 mg/L based on observed biological effects.  

The worst case value (96h-LC50 = 2.89 mg/L) is retained for risk assessment and classification purpose.

Description of key information

Acute toxicity test with di-tert-amyl peroxyde is available for fish.

The 96h-LC50 could not be statistically determined by the program using the default template for the OECD 203 guideline due to the mortality reported at the smallest test concentration (i.e. 0.21 mg/L). This observed mortality is not considered to be treatment-related as no death have been observed at 0.41, 0.55, 1.28 and 2.89 mg/L. Nevertheless, the 96h-LC50 is estimated to be between 2.89 and 5.52 mg/L based on observed biological effects.

The worst case value 96h-LC50 = 2.89 mg/L is retained for risk assessment and classification purpose.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

2.89 mg/L