3-hydroxypropyl octanoate

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:

2020-02-11 to 2020-04-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

30 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: For the determination of the actual test item concentrations, duplicate samples were taken from each test concentration and the control at the start and at the end of the two 24-hour test medium renewal periods. However, from the two highest test concentrations of 50 and 100 mg/L, samples were taken only from the first renewal period, since all daphnids were dead at the observation time at Day 1.
- Sample storage conditions before analysis: All samples were stored frozen (at -20 ± 5 °C) immediately after sampling

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test medium of the highest nominal concentration of 100 mg/L was prepared by completely dissolving 100.38 and 100.43 mg of test item in 1000 mL of test water by intense stirring for 15 minutes at room temperature in the dark, on Day 0 and Day 1, respectively. This highest concentration (clear solution) was used to prepare the test medium of the test concentration of 50 mg/L. The test media of the lower test item concentrations were prepared in a series of further dilution steps.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Stage and instar at study initiation: 6-24 hours old and were not first brood progeny
- Method of breeding: bred in IES Ltd Laboratories under temperature and light conditions identical to those of the tests. The cultivation of the parental daphnids is performed in reconstituted water of the quality identical to the water quality used in the test (with respect to pH, main ions, and total hardness).
- Source: the Daphnia Collection of the University of Basel/Switzerland in 2015
- Feeding during test: no

ACCLIMATION
- Acclimation: Test animals were bred under similar conditions as that used during the exposure period, therefore, additional acclimatization before the test was not necessary.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

19 to 20 °C

pH:

7.8 - 7.9

Nominal and measured concentrations:

Nominal: Control, 6.25, 12.5, 25, 50 and 100 mg/L;
Mean Measured: n.a., 4.7, 8.0, 19 and 50 mg/L, n.a.

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers
- Type: loosely covered with glass sheets
- Material, size, fill volume: glass, 100 mL, 50 mL test medium
- Volume of solution: 50 mL
- Aeration: no
- Renewal rate of test solution: 24 hours
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water (ISO Test water) according to OECD Guideline No. 202

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16-hour light to 8-hour dark cycle

EFFECT PARAMETERS: immobilsation after 24 and 48 hours of exposure

RANGE-FINDING STUDY
- Test concentrations: 1.0, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

10 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence limits: 9.0 - 12 mg/L

Duration:

48 h

Dose descriptor:

other: EC0 / NOEC

Effect conc.:

4.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

19 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

14 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95 % confidence limits: 12 - 15 mg/L

Details on results:

- Behavioural abnormalities: no
- Observations on body length and weight: no
- Mortality of control: no
- Other adverse effects control: no
- Immobilisation of control: no
- Abnormal responses:
- Any observations that might cause a difference between measured and nominal values: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: October 2019 (24-hour EC50: 1.8 mg/L (OECD 202: 24-hour EC50: 0.60-2.1 mg/L).

Reported statistics and error estimates:

The 24- and 48-hour EC50 and the 95 % confidence limits were calculated by Trimmed Spearman-Karber method for estimating median lethal concentrations, since the estimation based on the Probit or logit models was not be valid (p(F) > 0.05).
Statistical analysis was performed using ToxRat Professional®. The 24-hour and 48-hour NOEC, EC0 and EC100 were determined directly from the raw data.

Table 1: Effect of the test item on the Mobility of Daphnia magna

Nominal Test Item Concentration (mg/L)	Mean Measured Concentration (mg/L)	No. of Daphnids Tested	No. Of Daphnids/Replicate	Immobilized Daphnids after 24 Hours		Immobilized Daphnids after 48 Hours
				No.	[%]	No.	[%]
Control	---	20	5	0	0	0	0
			5	0		0
			5	0		0
			5	0		0
6.25	4.7	20	5	0	0	0	0
			5	0		0
			5	0		0
			5	0		0
12.5	8.0	20	5	0 (2F)	0	0	25
			5	0 (1F)		0
			5	0 (2F)		0
			5	0		0
25	19	20	5	3 (2F)	90	5	100
			5	5		5
			5	5		5
			5	5		5
50	50	20	5	5	100	--	--
			5	5		--
			5	5		--
			5	5		--
100	n.a.	20	5	5	100	--	-
			5	5		--
			5	5		--
			5	5		--

n.a.: Not analyzed, since this concentration was above the 48-hour EC100.

--: All daphnids already dead after 24 hours exposure time.

Values in parenthesis correspond to the number of mobile test animals with adverse effects.

F: Reduced swimming activity compared to the control animals

 

Table 2: 24-hour and 48-hour ECx values

ECx Values Immobility	Based on Mean Measured Test Item Concentration [mg/L]
24-hour EC50 95 %-confidence limits	14 12 - 15
24-hour EC0	8.0
24-hour EC100	50
48-hour EC50 95 %-confidence limits	10 9.0 – 12
48-hour EC0 and 48-hour NOEC	4.7
48-hour EC100	19

Analytical Results:

Table 3: Results for the Range-Finding Test

Sampling Day/Sample Age [day/hours]	Nominal Concentration of Test Item Cnom [mg/L]	Measured Concentration of Test Item X [µg/L]	Sample Preparation Factor F	Determined Concentration of Test Item c [mg/L]	% from Initially Measured [%]
0/0 (fresh)	Control	n.d.	126	< LOQ	n.a.
	10	42.0	251	10.6	106
	100	39.7	2651	105	105
2/48 (aged)	Control	n.d.	126	< LOQ	n.a.
	10	23.6	251	5.92	59
	10^a	36.9	251	9.27	93
	100	31.7	2651	84.2	84

LOQ: 0.130 mg test item /L (LOQ in range-finding test)

n.d. = not detected

n.a. = not applicable

a: without daphnia in the dark

The tabulated values of the samples represent rounded results obtained by calculation using the exact raw data.

Table 4: Results for Spiked Samples

Nominal Concentration of Test Item Cnom [mg/L]	Measured Concentration of Test Item X [µg]	Sample Preparation Factor F	Determined Concentration of Test Item C [mg/L]	Recovery Rate R [%]	Accuracy (Average Recovery) [%]	Precision (Relative Standard Deviation of Recovery) [%]
0	n.d.	102	n.a.	< LOQ	n.a.	-
1.13	10.5	102	1.07	95	95	4.7
1.13	9.96	102	1.02	90
1.13	10.9	102	1.12	99
1.13	11.1	102	1.13	100
1.13	10.1	102	1.03	91
62.6	101	669	67.5	108	110	1.8
62.6	102	669	68.4	109
62.6	106	669	70.8	113
62.6	104	669	69.4	111
62.6	102	669	68.5	109
Acceptance Target:					80 - 120	≤ 10

LOQ: 0.218 mg test item /L

n.d. = not detected

n.a. = not applicable

The tabulated values of the samples represent rounded results obtained by calculation using the exact raw data.

Table 5: Results for Test Samples

Sampling Day/Sample Age [day/hours]	Nominal Concentration of Test Item Cnom [mg/L]	Measured Concentration of Test Item X [µg/L]	Sample Preparation Factor F	Determined Concentration of Test Item c [mg/L]	% of Nominal Concentration [%]
0/0 (fresh)	Control	n.d.	102	< LOQ	n.a.
	6.25	63.6	102	6.49	104
	12.5	66.1	202	13.3	107
	25.50	62.4	402	25.1	100
	50	78.0	669	52.1	104
1/24 (aged)	Control	n.d.	102	< LOQ	n.a.
	6.25	46.8	102	4.77	76
	12.5	44.5	202	8.98	72
	25a	54.4	402	21.9	87
	25	68.0	402	27.4	109
	50	71.9	669	48.1	96
1/0 (fresh)	Control	n.d.	102	< LOQ	n.a.
	6.25	64.6	102	6.59	105
	12.5	63.0	202	12.7	102
	25	62.2	402	25.0	100
2/24 (aged)	control	n.d.	102	< LOQ	n.a.
	6.25	19.6/22.6^b	102	2.15*	34
	12.5	9.24/10.2^b	202	1.96*	16
	25	21.7/23.7^b	402	9.12*	36

LOQ: 0.218 mg test item / L

a: without daphnia, with light

b: retain sample

n.d. = not detected

n.a. = not applicable

* mean value

The tabulated values of the samples represent rounded results obtained by calculation using the exact raw data.

Validity criteria fulfilled:

yes

Conclusions:

The test item had acute toxic effects on Daphnia magna in a 48-hour semi-static test performed according to OECD 202. The 48-hour EC50 was calculated to be 10 mg/L with 95 % confidence limits of 9.0 and 12 mg/L.

Executive summary:

The acute toxicity of the test item to Daphnia magna was determined in a 48-hour semi-static test according to the OECD Guideline for Testing of Chemicals No. 202 (2004) and the Commission Regulation (EC) No. 440/2008, Part C.2. The nominal test item concentrations tested were 6.25, 12.5, 25, 50 and 100 mg/L. Additionally, a control (test water without test item) was tested in parallel. A semi-static test with test medium renewal after 24 hours was performed to maintain the concentration of the test item in the test medium as far as possible during the test period of 48 hours. Since the test item was instable in the range-finding test under the normal light conditions (16-hour light to 8-hour dark cycle) the main test was performed under reduced light conditions to avoid potential photolytic degradation of the test item.

At the start of the two renewal periods the measured concentrations in the test media of the nominal test concentrations of 6.25 to 50 mg/L were between 100 and 107 % of the nominal values. Thus, the correct dosage of the test item could be verified. During the test periods of 24 hours, the test item concentrations in the test media decreased. At the end of the two renewal periods, the test item concentrations were in the range of 72 to 96 % (Day 0 to Day 1) and 16 to 36 % (Day 1 to Day 2) of the nominal values, demonstrating a slightly to highly decrease of the test item concentrations during the 24-hour renewal periods. The reason for the degradation of the test item concentration mainly in the second renewal period could not be clarified. It can be assumed that an enhanced adsorption to the daphnids or an enhanced degradation by bacteria occurred, which were transferred with the surviving daphnids from the first renewal period.

The mean measured test item concentrations over the test period of 48 hours were calculated as the arithmetic mean of the two geometric means which were determined from the test item concentrations measured at the start and end of each of the two test medium renewal periods. Due to the decrease of the test item concentrations during the 24-hour renewal periods, the biological results were based on the mean measured test item concentrations. All validity criteria were met. The 48-hour NOEC was calculated to be 4.7 mg/L and the 48-hour EC50 was calculated to be 10 mg/L with 95 % confidence limits of 9.0 and 12 mg/L.

Description of key information

The test item had acute toxic effects on Daphnia magna in a 48-hour semi-static test performed according to OECD 202.

The 48-hour EC50 was calculated to be 10 mg/L with 95 % confidence limits of 9.0 and 12 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

10 mg/L

Additional information

The acute toxicity of the test item to Daphnia magna was determined in a 48-hour semi-static test according to the OECD Guideline for Testing of Chemicals No. 202 (2004) and the Commission Regulation (EC) No. 440/2008, Part C.2. The nominal test item concentrations tested were 6.25, 12.5, 25, 50 and 100 mg/L. Additionally, a control (test water without test item) was tested in parallel. A semi-static test with test medium renewal after 24 hours was performed to maintain the concentration of the test item in the test medium as far as possible during the test period of 48 hours. Since the test item was instable in the range-finding test under the normal light conditions (16-hour light to 8-hour dark cycle) the main test was performed under reduced light conditions to avoid potential photolytic degradation of the test item.

At the start of the two renewal periods the measured concentrations in the test media of the nominal test concentrations of 6.25 to 50 mg/L were between 100 and 107 % of the nominal values. Thus, the correct dosage of the test item could be verified. During the test periods of 24 hours, the test item concentrations in the test media decreased. At the end of the two renewal periods, the test item concentrations were in the range of 72 to 96 % (Day 0 to Day 1) and 16 to 36 % (Day 1 to Day 2) of the nominal values, demonstrating a slightly to highly decrease of the test item concentrations during the 24-hour renewal periods. The reason for the degradation of the test item concentration mainly in the second renewal period could not be clarified. It can be assumed that an enhanced adsorption to the daphnids or an enhanced degradation by bacteria occurred, which were transferred with the surviving daphnids from the first renewal period.

The mean measured test item concentrations over the test period of 48 hours were calculated as the arithmetic mean of the two geometric means which were determined from the test item concentrations measured at the start and end of each of the two test medium renewal periods. Due to the decrease of the test item concentrations during the 24-hour renewal periods, the biological results were based on the mean measured test item concentrations. All validity criteria were met. The 48-hour NOEC was calculated to be 4.7 mg/L and the 48-hour EC50 was calculated to be 10 mg/L with 95 % confidence limits of 9.0 and 12 mg/L.