tert-pentyl 2-ethylperoxyhexanoate

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:

2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP OECD guideline study without deviation

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Storage of samples: None
Samples treatment: Dilution with acetonitrile

Vehicle:

no

Details on test solutions:

Water solubility of the test item is close to 17 mg/L according to OECD 105. The stock solution was prepared the day the test was started.
For the range finding test and the definitive test, a stock solution was prepared by mixing 111 µL of TERT-AMYL PEROXY-2-ETHYLHEXANOATE (100 mg) to 1L of dilution water, under slow stirring during 1h30.
The mixture was then allowed to stand for about 2 hours.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna Straus (Cladocera, Crustacea), clone 5 or clone A. Animals come from a stock breading in the laboratory reared in VOLVIC® water added with vitamin B12, Na2SeO3, 5H2O, spiruline, Calcium, Magnesium unicellular green fresh-water algae Pseudokirchneriella subcapitata and Chlorella Vulgaris. Selection of test organisms less than 24 hours old is made by filtration.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

No data

Test temperature:

Definitive test : 19.22 +/- 0.2°C.

pH:

pH was measured at the highest concentration and in the control at the beginning and at all concentration and in the control the end of the test.

Dissolved oxygen:

Dissolved O2 was measured at the highest concentration and in the control at the beginning and at all concentration and in the control the end of the test.

Salinity:

Not relevant

Nominal and measured concentrations:

Preliminary test, nominal concentrations: 100, 50, 10, 5, 1 and 0.1 mg/L
Definitive test, nominal concentrations: 50, 23, 10.6, 4.8, 2.2 and 1 mg/L (factor 2.18).
See "Any other information on results incl. tables"

Details on test conditions:

Approximately 90% of the final volume of the test solution was added into test flasks. Five Daphnia magna aged from 6 to 24 hours were added into each test flask, which were then totally filled with the test solution (30 mL).

Preliminary test
Two replicates were prepared for each concentration. Two control flasks were prepared under the same conditions, with no test item. Test flasks were incubated in darkness at a temperature of 19.38 °C.

Definitive test
Volumetrics flasks were filled with the required volumes of the test item stock solution and dilution water in order to obtain the test solutions at concentrations varying from 1 mg/L to 50 mg/L.

Four replicates were prepared for each concentration. Four control flasks were prepared under the same conditions, with no test item. Test flasks were incubated in darkness at a temperature of 19.22 +/- 0.2°C.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

3.7 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: (2.7 – 5.8)

Details on results:

The appearance of the test solutions was visually checked at the beginning and at the end of the test. Solutions were found to be clear, colourless over the period of the test. No precipitation was observed at the end of the test.

Results with reference substance (positive control):

The OECD 202 method does not require to test a reference item to be tested simultaneously to the assay on the test item. However the sensitivity of the test system and the methodology are evaluated every month by performing an inhibition test on sodium dichromate. The nearest value of EC50 obtained on January 2013 was 0.97 mg/L.

Reported statistics and error estimates:

The inhibition of mobility data are analyzed using an Excel program. It was designed to calculate the EC50 value and the 95% confidence interval. Probit analysis is generally used to calculate the 24 and 48-hour EC50 values

Dissolved O2 and pH measured at the beginning and at the end (48h) of the exposition

 

Nominal concentrations	pH		Dissolved O2 (mg/L)
mg/L	T0	T48h	T0	T48h
0 (T)	7.89	7.54	9.0	7.8
1	7.65	7.63	8.9	8.2
2.2	7.69	7.56	8.9	7.8
4.8	7.71	7.60	8.9	8.1
10.6	7.73	7.62	8.9	8.1
23	7.73	7.57	9.0	7.8
50	7.73	7.59	8.8	7.9

 

 

Range finding test - Percentage of Daphnia magna inhibition

 

Nominal concentrations	Immobilisation (%)
(mg/L)	24 h	48 h
100	100	100
50	100	100
10	0	10
5	0	0
1	0	0
0.1	0	0
0 (T)	0	0

 

Definitive test - Percentage of Daphnia magna inhibition

 

Nominal concentrations	Immobilisation (%)
(mg/L)	24 h	48 h
50	35	95
23	0	20
10.6	0	0
4.8	0	0
2.2	0	0
1	0	0
0 (T)	0	0

Nominal and measured concentrations of the test item in non inoculated flasks at the beginning and at the end of the exposure period

 

Concentrations of TERT-AMYL PEROXY-2- ETHYLHEXANOATE
Nominal Concentration (mg/L)	Measured in non inoculated solutions
	Initial (mg/L)	Final (mg/L)	Final/Initial
			%
50.0	6.73	5.81	86.3
23.0	2.80	2.75	98.2
10.6	1.52	1.44	94.7
4.8	0.76	0.65	85.5
2.2	0.28	0.29	103.5
1.0	0.09	0.14	155
0 (T)	< LD	< LD	-

 

< DL : concentration lower than the Detection Limit of the analytical method (0.002 mg/L).

< QL : concentration lower than the Quantification Limit of the analytical method (0.007 mg/L).

 

As shown in the previous table, the final concentration of TERT-AMYL PEROXY-2-ETHYLHEXANOATE was maintained within the designated limit of 80-120 % of the initial measured concentrations in non- inoculated flasks (excepted the lowest concentration which is very low and very distant from the calculated EC50). Thus, the test item concentration was maintained throughout the duration of the test, and the estimation of effective concentrations (EC50) was based on initial measured concentrations

Validity criteria fulfilled:

yes

Conclusions:

EC50-48h = 3.7 mg/L (based on initial measured concentrations)

Executive summary:

The determination of the inhibition of mobility of Daphnia magna exposed to the test item TERT-AMYL PEROXY-2-ETHYLHEXANOATE for a duration of 48 hours was assessed according to the OECD Guideline 202. Daphnia magna were exposed under static conditions to TERT-AMYL PEROXY-2-ETHYLHEXANOATE dissolved in dilution water.

The concentration of test item causing a 50 % reduction in mobility (EC50) was estimated to be 3.7 mg/L (based on initial measured concentrations).

Description of key information

OECD 202, GLP, static conditions, key study, validity 1:
EC50-48h = 3.7 mg/L (based on initial measured concentrations)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

3.7 mg/L

Additional information

The determination of the inhibition of mobility of Daphnia magna exposed to the test item TERT-AMYL PEROXY-2-ETHYLHEXANOATE for a duration of 48 hours was assessed according to the OECD Guideline 202. Daphnia magna were exposed under static conditions to TERT-AMYL PEROXY-2-ETHYLHEXANOATE dissolved in dilution water.

The concentration of test item causing a 50 % reduction in mobility (EC50) was estimated to be 3.7 mg/L (based on initial measured concentrations).