Essential oil of Mentha Spicata L., Erospicata (Labiatae) obtained from aerial parts by steam distillation

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:

18 - 20 Oct 2016

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:

other: OECD 2000

Version / remarks:

Guidance document on aquatic toxicity testing of difficult substances and mixtures. OECD series on testing and assessment no. 23, ENV/JM/MONO(2000)6

GLP compliance:

yes (incl. QA statement)

Remarks:

Staatliches Gewerbeaufsichtsamt, Hildesheim, Germany

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control, 1.25, 2.5, 5.0, 10.0, 20.0, and 40.0 mg/L
- Sampling method: At the start of the exposure (0 h), sampling was carried out after preparation of the WAFs. After 24 h, samples were taken from additional replicates, which were prepared with test media, but without daphnia, and incubated under test conditions until sampling. At the end of the exposure (48 h), samples were taken directly from the test vessels.
- Sample storage conditions before analysis: All original samples were stored at 6 ± 2 °C until the start of the analysis, if necessary. Prepared samples were stored in an autosampler at RT until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Preparation of water accommodated fractions (WAF): For each loading level, an appropriate volume of the test item (its relative density of 0.8946 considered) was placed under the surface of the dilution water. The WAFs were prepared in brown glass flasks, which were filled with 2000 mL dilution water. A little headspace (approximately 100 - 200 mL) in the brown glass flasks was accepted to ensure a better mixing. The dispersions were shaken for 24 h with 20 rpm at room temperature. After completion of shaking and following a separation phase of at least 1 h of standing, the aqueous phase or WAF was removed from the approximate center of the water body by siphoning.
- Differential loading: yes
- Controls: dilution water without test item

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: Clone 5
- Feeding during test: no
- Age of the daphnia at the start of the exposure: < 24 h

CULTURING
- Conditions: In glass vessels ( 2 - 3 L capacity) with approximately 1.8 L culture medium, at 20 ± 2 °C, in an incubator, 16 h illumination, light intensity of max. 1500 lux.
- Culture medium: Elendt M4, according to guideline with a modified total hardness of 160 - 180 mg CaCO3/L
- Food type: mix of unicellular green algae (e.g. Pseudokirchneriella subcapitata and Desmodesmus subspicatus, in-house cultures originating from Sammlung von Algenkulturen, Göttingen, Germany)
- Amount: > E 06 cells/mL
- Frequency: at least 5 times per week ad libitum

ACCLIMATION
Not necessary because the dilution water was equivalent to the culture medium.

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES
Juvenile daphnia were removed from the culture vessels at the latest 24 h before the start of the exposure and discarded. The juveniles born within the following period of max. 24 h preceding the exposure were used for the test. No first brood progeny was used for the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

176 mg CaCO3/L (dilution water)

Test temperature:

0 h: 20.2 °C (dilution water)

pH:

0 h: 7.91 (control), 7.80 - 7.94 (treatments)
48 h: 7.78 - 7.86 (control), 7.71 - 7.88 (treatments)

Dissolved oxygen:

0 h: 9.04 mg/L (control), 8.65 - 8.83 (treatments)
48 h: 7.26 - 7.33 mg/L (control), 5.44 - 8.45 (treatments)

Conductivity:

0 h: 468 µS/cm (dilution water)

Nominal and measured concentrations:

control, 1.25, 2.50, 5.00, 10.0, 20.0, and 40.0 mg/L (nominal loading level)
< LOQ, 0.92, 1.83, 4.53, 8.65, 17.4, and 35.7 mg/L (measured at 48 h)

Details on test conditions:

TEST SYSTEM
- Test vessel: sealed glass flasks, 4.5 cm (ID), 9.5 cm (H)
- Type: closed, with screw caps made from polypropylene
- Test volume: 130 mL; Headspace: 0 mL
- 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: according to guideline
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH, dissolved oxygen, temperature, conductivity and total hardness of the dilution water were measured before the start of the exposure. PH values and dissolved oxygen concentrations of the test media were also measured in one additional replicate without daphnia at 0 h and in all replicates containing daphnia at 48 h. Temperature of the incubator was recorded continuously.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light/ 8 h dark
- Light intensity: diffuse light, max 1500 lux

EFFECT PARAMETERS MEASURED:
- Immoblization: after 24 h and 48 h

RANGE-FINDING STUDY
- Test concentrations: control, 1, 10, and 100 mg/L nominal loading level (WAF)
- Results used to determine the conditions for the definitive study: 100% mortality after 24 h at a nominal loading level of 100 mg/L. The tested WAF with a nominal loading of 100 mg/L was turbid and the WAF with a nominal loading of 1 mg/L was visually clear throughout the exposure phase.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EL10

Effect conc.:

1.4 mg/L

Nominal / measured:

nominal

Conc. based on:

other: test mat. (WAF)

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

3.57 mg/L

Nominal / measured:

nominal

Conc. based on:

other: test mat. (WAF)

Basis for effect:

mobility

Remarks on result:

other: 95% CI

Remarks:

2.79 - 4.43 mg/L

Duration:

48 h

Dose descriptor:

EL100

Effect conc.:

20 mg/L

Nominal / measured:

nominal

Conc. based on:

other: test mat. (WAF)

Basis for effect:

mobility

Details on results:

- Mortality of control: 5%
- Any observations that might cause a difference between measured and nominal values: The 1.25 to 20.0 mg/L WAFs were visually clear throughout the exposure period, whereas haziness was observed in the 40.0 mg/L WAF.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 (24 h) = 1.26 mg/L, 95% CI = 1.04 - 1.45 mg/L

Reported statistics and error estimates:

The EL10 and EL50 values after 24 and 48 h were calculated by sigmoidal dose-response regression. The respective 95% confidence limits were calculated from the standard error and the t-distribution. All calculations were carried out from the best-fit values with the software GraphPad Prism5.

The measured concentrations of the test item were in the range of 76 - 92% of the nominal values at the start of the exposure (0 h), 65 - 88% at 24 h and 73 - 91% at the end of the exposure (48 h).

Immobilization Rates after 24 and 48 h of exposure in the definitive test (n = 20, divided into 4 replicates with 5 daphnia each).

Nominal loading level of the WAF [mg/L]	IMMOBILIZATION [%]
	24 h					48 h
	replicates					replicates
	1	2	3	4	MV	1	2	3	4	MV
40.0	80	100	100	100	95	100	100	100	100	100
20.0	40	20	40	40	35	100	100	100	100	100
10.0	0	0	0	20	5	60	60	100	80	75
5.0	0	0	0	0	0	80	60	60	60	65
2.5	0	0	0	0	0	20	40	40	40	35
1.25	0	0	0	20	5	0	0	0	20	5
control	0	0	20	0	5	0	0	20	0	5

 

 

Validity criteria fulfilled:

yes

Conclusions:

EL50 (48 h) = 3.57 mg/L (nominal loading level, Daphnia magna, OECD 202)

Description of key information

EL50 (48 h) = 3.57 mg/L (nominal loading level, Daphnia magna, OECD 202)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

3.57 mg/L

Additional information

There is one GLP study available, in which the effect of the test substance towards aquatic invertebrates was assessed according to the OECD guideline 202.

The test substance is volatile (0.99 hPa at 20 °C) and a UVCB with poorly soluble components. Therefore, Daphnia magna was exposed to six water accommodated fractions (WAF) with nominal loading levels of the test substance ranging from 1.25 – 40.0 mg/L for 48 h in sealed glass flasks without headspace under controlled, static conditions. The concentrations of the test item were analytically verified by GC-MS.

Due to good analytical recovery, the effect levels are based on the nominal loading levels of the test item. The derived EL50 (48 h) was 3.57 mg/L (nominal loading level).