3-octoxypropane-1,2-diol

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:

01 Oct 2019 - 23 Nov 2019

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:

13 April 2004

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Samples for possible analysis were taken from all test concentrations and the control according to the schedule below.
Frequency: at t=0 h and t=48 h
Volume: 1.5 mL from the approximate centre of the test vessels
Storage: Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility.
At the end of the exposure period, the replicates were pooled at each test group before sampling.
Additionally, reserve samples of 1.5 mL were taken for possible analysis. If not used, these samples were stored in a freezer (≤-15°C) for a maximum of three months after delivery of the draft report, pending on the decision of the sponsor for additional analysis.

Vehicle:

no

Details on test solutions:

The batch of Saskine TM 80 tested was a clear colourless liquid with a purity of 99.8%. The test item was completely soluble in test medium at the concentrations tested, based on visual inspection. No correction was made for the purity/composition of the test item. Due to the light sensitivity of the test item, preparation of test solutions was performed under dimmed light conditions and glassware used was wrapped in aluminium foil.
Test item was dosed to test medium on a volume basis. The required volume was calculated using the available density of the test item (0.964 g/mL) provided by the Sponsor.
Preparation of test solutions started with the highest concentration of 100 mg/L applying 15 minutes of magnetic stirring to accelerate dissolution of the test item in medium and assure homogeneous solutions. Lower test concentrations were prepared by subsequent dilutions of the highest concentration in test medium. All test solutions were clear and colorless at the end of the preparation procedure.

Test organisms (species):

Daphnia magna

Details on test organisms:

Species: Daphnia magna (Crustacea, Cladocera) (Straus, 1820), at least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions.
Source: In-house laboratory culture with a known history.
Reason for selection: This system has been selected as an internationally accepted invertebrate species.
Validity of batch: Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20% , presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.
Characteristics: Daphnia, less than 24 hours old, from parental daphnids of more than two weeks old.

BREEDING
Start of each batch: Approximately 250 newborn daphnids, i.e. less than 3 days old, were placed into 5 litres of medium in an all-glass culture vessel.
Maximum age of the cultures: 4 weeks
Renewal of the cultures: After 7 days of cultivation, half of the medium twice a week.
Temperature of medium: 18-22°C
Feeding: Daily, a suspension of fresh water algae.
Culture medium: M7, as prescribed by Dr. Elendt-Schneider (Elendt, B.-P., 1990: Selenium deficiency in Crustacea. An ultrastructural approach to antennal damage in Daphnia magna Straus. Protoplasma 154, 25-33).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

180 mg/L expressed as CaCO3

Test temperature:

19°C

pH:

8.0 - 8.2

Dissolved oxygen:

8.7 - 9.5

Nominal and measured concentrations:

Nominal concentrations: 10, 18, 32, 56 and 100 mg/L.
Measured concentrations:Samples taken from all test concentrations and the control were analysed. The measured concentrations at the start of the test were 7.8, 14, 24, 46 and 78 mg/L at nominal concentrations of 10, 18, 32, 56 and 100 mg/L, respectively. During the exposure period, the concentrations remained stable, i.e. were at 86 - 103% relative to initial values at the end of the test. No test item responses were detected in the samples taken from the control.
The average exposure concentrations were 7.4, 13, 23, 42, 79 corresponding with nominal concentrations of 10, 18, 32, 56 and 100 mg/L, respectively.

Reference substance (positive control):

yes

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

28 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence interval: 23 -33 mg/L

Details on results:

No biologically relevant immobility was observed in the control and at the two lowest test concentrations throughout the test, while concentration-related immobility was recorded at the three highest test concentrations. Complete immobility was found at the highest test concentration after 48 hours of exposure. It should be noted that maximally 10% immobility is allowed in the control, and therefore, effects below 10% were considered biologically not relevant.
Moreover, large numbers of daphnids were observed to be floating at the surface of the solutions prepared at the two highest test concentrations after 24 hours of exposure. Microscopic observation of immobile daphnids revealed that there was no visible test item attached to their body’s outer surfaces. Therefore, recorded immobility is assumed not to be induced by a mechanical artefact.

Results with reference substance (positive control):

The 48h-EC50 was 0.55 mg/L with a 95% confidence interval between 0.50 and 0.62 mg/L. In conclusion, the sensitivity of this batch of Daphnia magna was in agreement with ISO International Standard 6341, October 2012 and the historical data collected at Charles River Den Bosch.

Reported statistics and error estimates:

The 48h-EC50-values was calculated from the weibits of the percentages of affected daphnids and the logarithms of the corresponding test item concentrations (average) using the maximum likelihood estimation method.
ToxRat Professional v 3.2.1 (ToxRat Solutions® GmbH, Germany) was used to perform the analysis.

Table 1          
Measured Concentrations and Calculated Average Exposure Concentrations (mg/L) 

Saskine^TM80 Nominal concentration (mg/L)	Measured concentrations (mg/L)		Average exposure conc. (mg/L)
	t=0h	t=48h
10	7.83	7.00	7.4
18	13.5	12.8	13
32	24.1	22.6	23
56	45.6	39.4	42
100	78.0	80.1	79

Table 2          
Number of Introduced Daphnids and Incidence of Immobility in the Final Test 

Time (h)	Replicate	Saskine^TM80; Nominal Concentrations (mg/L)
		Control	10 [7.4]	18 [13]	32 [23]	56 [42]	100 [79]
0	A	5	5	5	5	5	5
	B	5	5	5	5	5	5
	C	5	5	5	5	5	5
	D	5	5	5	5	5	5
	Total introduced	20	20	20	20	20	20
24	A	0	0(1)	0	0	1(1)	4(3)
	B	0	1	0	1	3(2)^#	5(1)
	C	0	0	1*	1	2(3)	5(3)
	D	0	0	0	0	2(2)	5(1)
	Total immobilised	0	1	1	2	8	19
	Effect %	0	5	5	10	40	95
48	A	0	0	0	2	5	5
	B	0	1	0	2	5(2)	5
	C	0	0	0	1	4(1)	5
	D	0	0	0	2	4(1)	5
	Total immobilised	0	1	0	7	18	20
	Effect %	0	5	0	35	90	100

( ) – number of daphnids observed trapped at the surface of the test solutions. These organisms were reimmersed into the respective solutions before recording of mobility, * The immobile daphnid was scored as mobile at the end of the test,^#Microscopic observation revealed no test item was attached to the immobile daphnids,
[ ] – average exposure concentrations (mg/L).

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the 48h-EC50 for Daphnia magna exposed to Saskine TM 80 was 28 mg/L based on average exposure concentrations (95% confidence interval between 23 and 33 mg/L).

Executive summary:

The short-term toxicity of Saskine^TM80 to aquatic invertebrates was determined in a daphnia acute study according to OECD guideline No. 202. In addition, procedures were based on the test methods described in the OECD series on testing and assessment number 23,2019.

A final test was performed based on the results of the preceding combined limit/range-finding test. Twenty daphnid per group (5 per replicate were exposed to un untreated control and to nominal concentrations of 10, 18, 32, 56 and 100 mg/L. The study was performed in the dark. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test. Based on the results of the analyses, average exposure concentrations of 7.4, 13, 23, 42 and 79 mg/L were calculated at nominal concentrations of 10, 18, 32, 56 and 100 mg/L, respectively.

No biologically relevant immobility was observed in the control and at the two lowest test concentrations throughout the test, while concentration-related immobility was recorded at the three highest test concentrations. Complete immobility was found at the highest test concentration after 48 hours of exposure.

In conclusion, the 48h-EC₅₀ for Daphnia magna exposed to Saskine^TM80 was 28 mg/L based on average exposure concentrations (95% confidence interval between 23 and 33 mg/L). The study met the accepability criteria prescribed by the study plan and was considered valid.

Description of key information

The 48h-EC₅₀for Daphnia magna exposed to Saskine^TM80 was 28 mg/L based on average exposure concentrations (95% confidence interval between 23 and 33 mg/L)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

28 mg/L

Additional information

The short-term toxicity of Saskine^TM80 to aquatic invertebrates was determined in a daphnia acute study according to OECD guideline No. 202. In addition, procedures were based on the test methods described in the OECD series on testing and assessment number 23,2019.

A final test was performed based on the results of the preceding combined limit/range-finding test. Twenty daphnid per group (5 per replicate were exposed to un untreated controland to nominal concentrations of 10, 18, 32, 56 and 100 mg/L. The study was performed in the dark. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test. Based on the results of the analyses, average exposure concentrations of 7.4, 13, 23, 42 and 79 mg/L were calculated at nominal concentrations of 10, 18, 32, 56 and 100 mg/L, respectively.

No biologically relevant immobility was observed in the control and at the two lowest test concentrations throughout the test, while concentration-related immobility was recorded at the three highest test concentrations. Complete immobility was found at the highest test concentration after 48 hours of exposure.

In conclusion, the 48h-EC₅₀ for Daphnia magna exposed to Saskine^TM80 was 28 mg/L based on average exposure concentrations (95% confidence interval between 23 and 33 mg/L). The study met the accepability criteria prescribed by the study plan and was considered valid.