7-methyl-3-methyleneocta-1,6-diene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 March 2014 - 5 January 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Well conducted and well described study in accordance with GLP and OECD Guideline No 201 without any major deviation.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Principles of method if other than guideline:

not applicable

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

Analytical monitoring:

yes

Details on sampling:

Concentrations: samples for analysis were taken from the control and all test concentrations

Sampling method: samples were taken at the start (t = 0 h) and every day thereafter until the end of the test

Storage: samples were analysed directly after sampling

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
Method: preparation was performed in closed conditions and minimum headspace to avoid loss of test substance through volatilisation from water. A water volume of 1 L was placed in vessel. An excess of substance (0.85 g) was added to the surface of water. The stock solution was prepared by slow-stirring and maintaining the vortex in the centre extending maximally ca. 10% of vessel depth. After 24 ± 2 hours of gentle stirring, the saturated aqueous phase was taken out of the drain port. The first 100 mL were discarded and samples were taken from the following stock solution and chemically analyzed.

Evidence of undissolved material: no (the test sample formed a clear colourless solution)

Controls: test water without test substance but treated in the same way as the test substance solutions.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
Common name: Algae
Strain: Pseudokirchneriella, CCAP 278/4
Origin: Museum National d’Histoire Naturelle - 12, rue Buffon, Case N°19 - 75005 PARIS, bred in the laboratory under standardised conditions according to the test guidelines

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

no

Hardness:

150 mg/L as NaHCO3

Test temperature:

23 +/- 2°C

pH:

8.00-8.14 (control and test vessels, start) 8.11-9.06 (control and test vessels, end)

Dissolved oxygen:

not reported

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations: 0.3, 0.5, 0.8, 1.2, 1.9 and 3.0 mg/L
Measured concentrations: 0.101, 0.101, 0.217, 0.289, 0.358 and 0.805 mg/L

Details on test conditions:

TEST SYSTEM
Test vessel: closed glass flask (100 mL)
Aeration: yes
Shaking: during incubation, the algal cells were kept in suspension by continuous shaking.
Initial cells density: 5000 cells/mL
Control end cells density: 59.0 x 10^4 cells/mL
No. of vessels per concentration (replicates): 3
No. of vessels per control (replicates): 6
Additional replicate of each test concentration without algae: a replicate of each test concentration with and without algae was prepared in order to assess the abiotic stability of the test substance during the test period and to determine maintenance of actual concentrations by chemical analyses compared to that in the algae samples

GROWTH MEDIUM
Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
Source/preparation of dilution water: original medium of OECD Guideline 201, prepared using sterilised water
Culture medium: original medium of OECD TG 201
Intervals of water quality measurement: temperature was measured continuously in the growth chamber, over the study period and pH was recorded at the beginning and at the end of the test in one vessel per concentration and the control.

OTHER TEST CONDITIONS
Sterile test conditions: yes
Photoperiod: continuous illumination
Light intensity and quality: 4400-8880 Lux

EFFECT PARAMETERS MEASURED
Determination of cell concentrations: cell numbers were counted daily by microscope using a counting chamber.

TEST CONCENTRATIONS
Spacing factor for test concentrations: 1.58

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.342 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 0.327-0.363

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.31 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: 95%CL 0.270-0.368

Details on results:

ErC10 (72 h) = 0.274 (0.249-0.290) mg/L (measured); EyC10 (72 h) = 0.199 (0.133-0.236) mg/L (measured)
ErC20 (72 h) = 0.296 (0.276-0.310) mg/L (measured); EyC20 (72 h) = 0.232 (0.175-0.266) mg/L (measured)
ErC50 (72 h) = 0.342 (0.327-0.363) mg/L (measured); EyC50 (72 h) = 0.310 (0.270-0.368) mg/L (measured)

Results with reference substance (positive control):

Results with reference substance valid
EC50: 0.34 mg/L (growth rate)

Reported statistics and error estimates:

The software ToxRat® Professional was used for the determination of the effective concentrations. The EC50 value was determined by Probit analysis using linear max. likelihood regression.

Validity criteria fulfilled:

yes

Conclusions:

The 72h-ErC50 and the 72h-ErC10 of MYRCENE for Pseudokirchneriella subcapitata was determined to 0.342 mg/L and 0.274 mg/L respectively (based on growth rate).

Executive summary:

An algal toxicity study was performed in accordance with OECD Guideline No 201 and GLP. Following a preliminary range-finding test, Pseudokirchneriella subcapitata algae were exposed to MYRCENE at nominal concentrations of 0.3, 0.5, 0.8, 1.2, 1.9 and 3.0 mg/L (three replicate flasks per test concentration and six replicates for control) for 72 h, under constant illumination and shaking at a temperature of 21-25°C. Measurements of biomass, growth inhibition and yield were done by determination of cell densities at 24, 48 and 72 h using a counting chamber. The results obtained with positive control (potassium chromate) were in accordance with guideline requirements.

The concentrations of the test item (with and without algae) were measured at the start of the study and at the 72-h incubation period. The concentrations were not satisfactorily maintained within ± 20% of the initial concentrations, thus the results were based on the geometric mean of measured exposure concentrations in the abiotic test.

The 72h-EC₁₀ and 72h-EC₅₀ values, based on growth rate, were 0.274 and 0.342 mg/L respectively, calculated as geometric mean of measured concentration.

Description of key information

An algal toxicity study was performed in accordance with OECD Guideline No 201 and GLP.

Pseudokirchneriella subcapitata algae were exposed to MYRCENE at nominal concentrations of 0.3, 0.5, 0.8, 1.2, 1.9 and 3.0 mg/L for 72 h, under constant illumination and shaking at a temperature of 21-25°C. Measurements of biomass, growth inhibition and yield were done by determination of cell densities.

The 72-hr EC50 was 0.342 mg/L. The 72-h EC10 was 0.274 mg/L.

Based on the results of this study, myrcene is classified:
- dangerous for the environment according to Directive 67/548/EEC "R50/53: very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment"
- and hazardous to the aquatic environment under Regulation (EC) No 1272/2008 (CLP) - Category Acute 1 and Category Chronic 1.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.342 mg/L

Additional information

Key sudy conducted under GLP according to OECD 201 Guideline and EU Method C3.

The concentrations of the test item were not satisfactorily maintained within ± 20% of the initial concentrations throughout the test, the EC₅₀ were based on geometric mean of the measured oncentrations in abiotic replicates.