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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: read-across from a guideline study
Justification for type of information:
The read-across justification is presented in the Endpoint summary Aquatic toxicity, because for fish, Daphnia, and algae the same source substance is used, and the reasoning is included in one document. The accompanying files are also attached there.
Reason / purpose:
read-across source
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.63 mg/L
Basis for effect:
mobility
Remarks on result:
other: read-across from Terpinolene
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
November 2012 - April 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
This information is used for read-across to the Terpene hydrocarbon alcohols.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Principles of method if other than guideline:
not applicable
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
not applicable
Analytical monitoring:
yes
Details on sampling:
Concentrations: single samples for analysis were taken from the control and all test concentrations from replicates without daphnids (except at the end of the test : replicates with daphnids).

Sampling method: samples were taken at the start (t = 0 h) and every 24 h thereafter in old and new solutions and the control.

Storage: samples were analysed directly after sampling.

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
Method: slow-stirring in a closed vessel with minimum headspace
The test sample formed a clear colourless solution and appeared to be completely soluble and stable when mixed with test water at the concentrations prepared.

Controls: test water without test substance but treated in the same way as the test substance solutions.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
Common name: Daphnia magna (Straus)
Strain: Clone 5
Source: LIEBE - CNRS UMR 7146 - UFR SciFA - Université de Lorraine Campus Bridoux - Bât. IBISE, 8, rue du Général Delestraint - 57070 METZ, bred in the Laboratoires des Pyrénées
Age at study initiation: less than 24 h
Method of breeding: parthenogenesis
Feeding during the test: no

ACCLIMATION
Acclimation period: 48 h
Acclimation conditions: same as test
Type and amount of food: mix of 3 algae strains: Chlorella vulgaris = 2.5x106 cells/mL/day/daphnid, Desmodesmus subspicatus = 2.5x106 cells/mL/day/daphnid and Pseudokirchneriella subcapitata = 5x106 cells/mL/day/daphnid
Feeding frequency: daily
Only daphnids not older than 24 hours were used for the test

VALIDITY OF BATCH OF DAPHNIDS
Health during acclimation (any mortality observed): daphnids originated from a healthy stock, showing no signs of stress such as mortality, presence of males, ephippia or discoloured animals.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
not applicable
Hardness:
250 mg/L (CaCO3)
Test temperature:
19.5-20.2°C
pH:
7.66-7.84 (whole test period)
Dissolved oxygen:
8.31-0.18 mg/L (whole test period)
Salinity:
not applicable
Nominal and measured concentrations:
Nomina concentrations: 0.2, 0.3, 0.4, 0.5, 0.7, 1.0 mg/L
Measured concentrations: 0.14, 0.24, 0.33, 0.41, 0.57, 0.82 mg/L (averaged)
Details on test conditions:
TEST SYSTEM
Test vessel: glass test tubes sealed with screwcaps
Volume: 20 mL (without headspace)
Aeration: no
Renewal rate of test solution: daily
No. of organisms per vessel: 5
No. of vessels per concentration (replicates): 4
No. of vessels per control (replicates): 4
3 abiotic replicates for control and test concentration
Biomass loading rate: 5/20 mL

TEST MEDIUM / WATER PARAMETERS
Source/preparation of dilution water: reconstituted water, as prescribed by OECD Guideline 202
Conductivity: < 10µS/cm
Intervals of water quality measurement: water temperature was recorded continuously throughout the test. Dissolved oxygen concentrations and pH were recorded at the start of the test (t = 0 h), at t = 24 h (new and old solutions) and at the end of the test (t = 48 h) in all vessels.

OTHER TEST CONDITIONS
Adjustment of pH: no
Photoperiod: 16h light and 8h dark

EFFECT PARAMETERS MEASURED
Immobility and abnormal behaviour were determined by visual observation after 24 and 48 h. The daphnids were considered to be immobile if they were not able to swim within 15 seconds after gentle agitation of the test vessels.

TEST CONCENTRATIONS
Spacing factor for test concentrations: 1.38

Range finding study
Test concentrations: 0.6-1.0-2.0-5.9 mg/L
Results used to determine the conditions for the definitive study: 30% inhibition was observed at 1.0 mg/L and 100% inhibition was observed at two highest test concentration
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.634 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95%CL: 0.332-0.823
Results with reference substance (positive control):
- Results with reference substance are valid.
- EC50: 0.97 mg/L
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 48-h EC50 value for aquatic invertebrates (D. magna) is 0.634 mg/L, based on mean measured concentrations.
Executive summary:

For aquatic invertebrates, an acute toxicity study was performed according to OECD TG 202 and in compliance with GLP criteria. Following a preliminary range-finding test, groups of daphnids (4 replicates of 5) were exposed to Terpinolene at nominal test concentrations of 0.2, 0.3, 0.4, 0.5, 0.7 and 1.0 mg/L. Immobilisation of daphnids was determined in a semi-static 48-h test by visual observation after 24 and 48 h. The concentrations of the test item were measured at the start (t = 0 h), at t = 24 h (new and old solutions) and at the end of the test (t = 48 h). Concentrations measured in freshly prepared solutions and in 24-h old solutions revealed that the concentrations of the test item were not satisfactorily maintained within ± 20 % of the initial concentrations. Thus, the evaluation of the effects on Daphnia magna was based on the geometric mean of the measured concentrations: 0.14, 0.24, 0.33, 0.41, 0.57 and 0.82 mg/L.

The lowest observed effect concentration based on immobilisation was 0.332 mg/L. At 0.823 mg/L, 100% of daphnids were immobilised. No sub-lethal effects were reported. Therefore, the 48h-EC50 of Terpinolene for Daphnia magna was estimated to be 0.634 mg/L, based on mean measured concentrations.

Description of key information

The Terpene hydrocarbon acute Daphnia toxicity is based on read-across from the close structural analogue Terpinolene.

Terpinole acute Daphnia toxicity

For Terpinolene, a daphnid acute toxicity study was performed according to OECD TG 202 and in compliance with GLP criteria. Following a preliminary range-finding test, groups of daphnids (4 replicates of 5) were exposed to Terpinolene at nominal test concentrations of 0.2, 0.3, 0.4, 0.5, 0.7 and 1.0 mg/L. Immobilisation of daphnids was determined in a semi-static 48-h test by visual observation after 24 and 48 h. The concentrations of the test item were measured at the start (t = 0 h), at t = 24 h (new and old solutions) and at the end of the test (t = 48 h). Concentrations measured in freshly prepared solutions and in 24-h old solutions revealed that the concentrations of the test item were not satisfactorily maintained within ± 20 % of the initial concentrations. Thus, the evaluation of the effects on Daphnia magna was based on the geometric mean of the measured concentrations: 0.14, 0.24, 0.33, 0.41, 0.57 and 0.82 mg/L. The lowest observed effect concentration based on immobilisation was 0.332 mg/L. At 0.823 mg/L, 100% of daphnids were immobilised. No sub-lethal effects were reported. Therefore, the 48h-EC50 of Terpinolene for Daphnia magna was estimated to be 0.634 mg/L, based on mean measured concentrations.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.634 mg/L

Additional information