3,7-dimethyloct-1-en-3-yl acetate

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:

2014-11-04 to 2014-12-18

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:

yes

Remarks:

reconstituted test water according to ISO 6341 was used as proposed in OECD Guidline 23 (2000) on testing of difficult substances

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

yes

Remarks:

reconstituted test water according to ISO 6341 was used as proposed in OECD Guidline 23 on testing of difficult substances

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Chemical name: 3,7-dimethyloct-1-en-3-ol
- CAS Number: 18479-49-7

Analytical monitoring:

yes

Details on sampling:

- Sampling method: For the determination of the actual test item concentrations, duplicate samples were taken from each treatment at the start and at the end of the test (after 48 hours). For the 48-hour stability samples, the contents of the respective replicates were combined prior to sampling. The concentrations of the test item 3,7-dimethyloct-1-en-3-ol were analyzed in one of the duplicate test media samples of all test concentrations from both sampling times (0 and 48 hours). From the control, one of the duplicate samples was analyzed per sampling time.
- Sample storage conditions before analysis: All samples were stored deep-frozen (at about -20 °C) immediately after sampling. Based on preexperiments for investigation of the storage stability, the test item was found to be stable in the test water under these storage conditions.

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 in a completely
filled and tightly closed stirring vessel by completely dissolving 109.3 mg of test item in 1090 mL of test water using intense stirring for 3 hours at room temperature in the dark. Adequate volumes of this test medium were serially diluted with test water to prepare the lower concentrated test media. The test media were prepared just before the introduction of the daphnids (i.e., start of the test).
- Controls: negative (blank) control (test medium only), positive control
- Test concentration separation factor: In the definitive test, the enlarged spacing factor of 3.2 between the test concentrations was chosen based on the results of the range-finding test that documented a rather flat concentrationeffect relationship; therefore, a large concentration range had to be tested.
- Evidence of undissolved material: no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: clone 5 (defined by the supplier)
- Age at study initiation: 6-24 hours old
- Stage and instar at study initiation: not first brood progeny
- Method of breeding: reconstituted water of the quality identical to the water quality used in the test (with respect to pH, main ions, and total hardness) and under temperature and light conditions identical to those of the test; generally fed three times a week with an algal suspension of the green algae Desmodesmus subspicatus Chodat, Strain No. 86.81 SAG, supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, 37073 Göttingen / Germany) and cultivated at the laboratory under standardized conditions or a mixture of this algal suspension and a commercial fish diet (Tetra Min Hauptfutter, supplied by TETRA-Werke, 49304 Melle / Germany).
- Source: originally supplied by the University of Sheffield, UK in 1992
- Feeding during test: no

ACCLIMATION
- Acclimation period: none, breeding conditions same as test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

post exposure observation not performed

Hardness:

2.5 mmol/L; 250 mg/L as CaCO3

Test temperature:

21-22 °C

pH:

7.8

Dissolved oxygen:

>= 8.4 mg/L

Salinity:

not applicable

Conductivity:

not specified

Nominal and measured concentrations:

nominal: 1, 3.2, 10, 32, 100 mg/L; measured: 0.965, 3.08, 9.39, 33.0, 95.8 mg/L (fresh medium, 0 d); 0.931, 2.99, 9.63, 32.5, 93.8 mg/L (old medium, 2 d), corresponding to 93-103 % of nominal; displayed measured values are rounded results obtained by calculation using the exact raw data

Details on test conditions:

TEST SYSTEM
- Test vessel: tubes
- Type: closed, tightly sealed with glass stoppers
- Material, nominal volume, fill volume, headspace: glass, nominal volume 50 mL, fill volume about 60 mL i.e. completely filled with test medium to minimize the headspace
- Volume of solution: about 60 mL
- Test medium volume per animal: 10 mL
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4
- No. of vessels per control: 4

TEST MEDIUM
- Source/preparation of dilution water: based on the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000; reconstituted test water according to ISO 6341
CaCl2 × 2H2O: 2.0 mmol/L
MgSO4 × 7H2O: 0.5 mmol/L
NaHCO3: 0.75 mmol/L
KCl: 0.075 mmol/L
Water Hardness: 2.5 mmol/L
Alkalinity: 0.8 mmol/L

The ratio of Ca:Mg and Na:K was 4:1 and 10:1, respectively, based on molarities. The test water was aerated prior to the start of the study until oxygen saturation was reached. During the test period, the test water was not aerated.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16-hour light to 8-hour dark cycle with a 30-minute transition period
- Light intensity:between 800 and 1060 Lux

EFFECT PARAMETERS MEASURED: immobility after 24 and 48 hours of exposure

RANGE-FINDING STUDY
- Test concentrations: 0 (control), 1.0, 10, 100 mg/L (nominal)
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

24 h

Dose descriptor:

IC50

Effect conc.:

51 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence interval: 32 - 100 mg/L

Duration:

24 h

Dose descriptor:

EC0

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC100

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

39 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence interval: 10 - 100 mg/L

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: no
- Observations on body length and weight: no
- Other biological observations: please see Table 1 in below section "Any other information on results incl. tables"
- Mortality of control: no
- Other adverse effects control: no
- Immobilisation of control: no
- Abnormal responses: no
- Any observations that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Relevant effect levels: 48-hour EC50: 1.0 mg/L
- Remark: For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate was tested as a positive control twice a year. The result of the latest positive control test in August 2014 showed that the sensitivity of the test organisms was within the historical range of the laboratory (48-hour EC50 from 2000 to 2014: 0.36-1.1 mg/L).

Reported statistics and error estimates:

EC values were determined according to SACHS, L. (1984): Applied statistics, Springer series in statistics, Springer

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

Nominal test item concentration [mg/L]	No. of daphnids tested	Immobilized daphnids after 24 hours		Immobilized daphnids after 24 hours
		No.	[%]	No.	[%]
Control	20	0	0	0	0
1.0	20	0	0	0 (15B,C)	0
3.2	20	0 (4C)	0	4 (16C,D,E)	20
10	20	1 (3C,E)	5	1 (19C,D,E)	5
32	20	3 (7B,C,E)	15	8 (12C,D,E)	40
100	20	20	100	20	100

Values in parenthesis: number of mobile test animals with adverse effects:
A: daphnids trapped at the water surface
B: daphnids sticking together
C: antennae sticking together
D: daphnids discolored/pale
E: spina stuck
F: reduced swimming activity

 

Table 2: Test condition parameters

Nominal test item concentration [mg/L]	Start (0 hours)			End (48 hours)
	pH	Oxygen [mg/L]	Temperature [°C]	pH	Oxygen [mg/L]	Temperature [°C]
Control	7.8	8.4	22	7.8	8.9	21
1.0	7.8	8.5	22	7.8	8.9	21
3.2	7.8	8.4	22	7.8	8.9	21
10	7.8	8.5	22	7.8	8.9	21
32	7.8	8.5	22	7.8	9.0	21
100	7.8	8.6	21	7.8	9.0	21

 

Table 3: Analytical results

Timepoint [day]	Nominal concentration of test item [mg/L]	Measured concentration of test item x [mg/L]	Sample preparation factor F	Determined concentration of test item c [mg/L]	% of nominal concentration [%]
0 (fresh)	Control	*	0.5	< LOQ	n.a.
	1	1.93	0.5	0.965	96
	3.2	6.15	0.5	3.08	96
	10	1.88	5	9.39	94
	32	6.61	5	33.0	103
	100	1.92	50	95.8	96
2 (old)	Control	*	0.5	< LOQ	n.a.
	1	1.86	0.5	0.931	93
	3.2	5.97	0.5	2.99	93
	10	1.93	5	9.63	96
	32	6.50	5	32.5	102
	100	1.88	50	93.8	94

 

CONSIDERATIONS ON VALIDITY OF STUDY

The test is considered to be valid, as in the control no daphnids showed immobilization or other signs of disease or stress (e.g., discoloration or unusual behavior such as trapping at the surface water). Furthermore, the dissolved oxygen concentration at the end of the test was greater than 3 mg/L in the control and test vessels.

Validity criteria fulfilled:

yes

Conclusions:

In a static Acute Immobilisation Test according to OECD TG 202 with Daphnia magna the 48-hour EC50 of the test item was determined to be 39 mg/L.

Executive summary:

The acute toxicity of the test item to Daphnia magna was determined in a 48-hour static test according to the Commission Regulation (EC) No. 440/2008, Part C.2 and the OECD Guideline for Testing of Chemicals, No. 202 (2004). The nominal test item concentrations tested were 1.0, 3.2, 10, 32 and 100 mg/L. The enlarged spacing factor of 3.2 between the test concentrations was chosen based on the results of the range-finding test that documented a rather flat concentration effect relationship; therefore, a large concentration range had to be tested. Additionally, a negative control group was tested in parallel. The suitability of the test system was confirmed in a separate test with the reference compound potassium dichromate. For each treatment, 20 daphnids were used divided into four replicates of five daphnids each. The volume of test solution provided for each daphnid was greater than 10 mL. Thus, the requirement of the test guidelines for the minimum volume of 2 mL test medium per daphnid was fulfilled. The daphnids were randomly distributed to the test vessels at the initiation of the test. As the test item is a volatile substance, the test was performed using glass tubes completely filled with test medium, minimizing the headspace, and tightly sealed with glass stoppers to avoid losses of test item. The preparation of the test media was based on the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000. The measured concentrations of the test item in the test media of all test concentrations were analytically verified using a GC-FID method to be between 94 and 103% of the nominal values at the start of the test and between 93 and 102% at the end of the test. The biological results were related to the nominal concentrations of the test item, since the correct dosage was confirmed. As a result, the 48-hour EC50 was determined to be 39 mg/L. All validity criteria of the guidelines were fulfilled. The study is hence regarded valid and acceptable for assessment.

Description of key information

In a static Acute Immobilisation Test according to OECD TG 202 with Daphnia magna the 48-hour EC50 of the read-across source substance was determined to be 39 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

39 mg/L

Additional information

No eperimental information on short-term toxicity to aquatic invertebrates is available for the registration substance itself, but for the read-across source substance 3,7-dimethyloct-1-en-3-ol (CAS no. 18479-49-7).

 

Key information

The acute toxicity of the read-across source substance to Daphnia magna was determined in a 48-hour static test according to the Commission Regulation (EC) No. 440/2008, Part C.2 and the OECD Guideline for Testing of Chemicals, No. 202 (2004). The nominal test item concentrations tested were 1.0, 3.2, 10, 32 and 100 mg/L. The enlarged spacing factor of 3.2 between the test concentrations was chosen based on the results of the range-finding test that documented a rather flat concentration effect relationship; therefore, a large concentration range had to be tested. Additionally, a negative control group was tested in parallel. The suitability of the test system was confirmed in a separate test with the reference compound potassium dichromate. For each treatment, 20 daphnids were used divided into four replicates of five daphnids each. The volume of test solution provided for each daphnid was greater than 10 mL. Thus, the requirement of the test guidelines for the minimum volume of 2 mL test medium per daphnid was fulfilled. The daphnids were randomly distributed to the test vessels at the initiation of the test. As the test item is a volatile substance, the test was performed using glass tubes completely filled with test medium, minimizing the headspace, and tightly sealed with glass stoppers to avoid losses of test item. The preparation of the test media was based on the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000. The measured concentrations of the test item in the test media of all test concentrations were analytically verified using a GC-FID method to be between 94 and 103% of the nominal values at the start of the test and between 93 and 102% at the end of the test. The biological results were related to the nominal concentrations of the test item, since the correct dosage was confirmed. As a result, the 48-hour EC50 was determined to be 39 mg/L. All validity criteria of the guidelines were fulfilled. The study is hence regarded valid and acceptable for assessment.

 

Conclusion

Based on reliable information for the read-across source substance, the 48-hour EC50 of the target substance is considered to be 39 mg/L.