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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
14 Sep - 05 Oct 2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions
Justification for type of information:
see Analogue justification
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Deviations:
yes
Remarks:
hardness of test water was lower than that recommended by the Guideline
GLP compliance:
yes
Remarks:
according to the Japanese GLP Standard
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Melting point: 61.7 °C
- Boiling point: 390 °C
- Vapour pressure: 0.998 mmHg (154 °C)
- Water solubility: 0.00072% (20 °C)
- Solubility: freely soluble in diethyl ether, soluble in ethanol
Analytical monitoring:
yes
Details on sampling:
- Concentrations: control, vehicle control, nominal concentration: 0.510 mg/L
- Sampling method: test water was sampled from one vessel in each group at day 0, 1, 7, 8, 14 and 15.
- Sample storage conditions before analysis: analysis was conducted immediately after sampling, no storage
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: stock solution (5100 mg/L) was prepared with test substance and vehicle at the study initiation by shaking with hands. Stock solution was stable in a refrigerator > 21 days. Test water was prepared with dilution water and stock solution and mixed for 1 minute with a magnetic stirrer.
- Controls: dilution water with/without vehicle
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): N, N- dimethyl formaldehyde (DMF)
- Concentration of vehicle in test medium (final test solution): 0.1 mg/L
- Evidence of undissolved material: not observed
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Source: Incorporated Administrative Agency, National Institute for Environmental Studies, Tsukuba, Japan
- Age at study initiation: max. 24 hours
- Feeding during test: yes
- Food type: Chlorella vulgaris
- Amount: 0.15 mgC / day

ACCLIMATION
- Acclimation period for parental animals: 2 - 4 weeks
- Acclimation conditions: same as test
- Type and amount of food: Chlorella vulgaris, 0.1 - 0.2 mgC/day
- Health during acclimation: < 5% mortality in 2 weeks before exposure and no males and no ephippia was observed
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
21 d
Hardness:
46 - 52 mg/L (CaCO3)
Test temperature:
19.8 - 20.1 °C (20 ± 1 °C)
pH:
7.3 - 7.9
Dissolved oxygen:
7.1 - 8.5 mg/L (> 60% of saturated oxygen)
Nominal and measured concentrations:
nominal concentration: 0.51 mg/L
measured concentration (time weighted mean): 0.22 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL beaker
- Type: closed (covered with teflon-sheet)
- Material, fill volume: glass, 80 mL
- Renewal rate of test solution: once in 24 hours
- No. of organisms per vessel: 1
- No. of vessels per concentration: 10
- No. of vessels per control: 10
- No. of vessels per vehicle control: 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: aerated tap water charcoal-treated and dechlorinated with sodium thiosulfate, in Yokohama, Japan
- Culture medium different from test medium: parental animals were cultured in same dilution water 48 hours before exposure.
- Intervals of water quality measurement: every 6 months

OTHER TEST CONDITIONS
- Adjustment of pH: not adjusted
- Photoperiod: 16 hours in light, 8 hours in dark
- Light intensity: < 800 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
immobility, mortality for parental animals, number of offspring

TEST CONCENTRATIONS
- Justification for using less concentrations than requested by guideline: water solubility was 0.51 mg/L
- Range finding study: acute toxicity test was performed
- Test concentrations: 0.510 mg/L (nominal concentration)
- Results used to determine the conditions for the definitive study: EC50 for 48 hours: >0.510 mg/L
Reference substance (positive control):
yes
Remarks:
potassium dichromate (reagent grade)
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
> 0.22 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks:
based on cumulative number of juveniles produced per adult
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
> 0.22 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks:
based on cumulative number of juveniles produced per adult
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
> 0.22 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks:
based on cumulative number of juveniles produced per adult
Details on results:
- Mortality of parent animals after 21 days: control: 10%, solvent control: 10%, 0.22 mg/L (time weighted mean measured cencentration): 10%
- Cumulative no. of offspring produced per female: see table 1
- Number of males and females (parental): 10 females in each group
- Time to first brood release or time to hatch: 8 - 9 days
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- EC50: 0.75 ± 0.14 mg/L
Reported statistics and error estimates:
Student-t test and Welch-t test

Table 1: Cumulative number of juveniles produced per adult alive for 21 days

Nominal Concentration,

mg/L

(Measured (a) Concentration, mg/L)

Mean Cumulative Numbers of Living Young after 21 Days(Mean ± S.D.)

Inhibition rate (%)

Significant difference

Control

 119.6 ± 10.5

 

Solvent control

119.8± 7.9

 

0.510 (0.22)

128.7 ± 13.4

-7.4

-

(a): Time-weighted mean measured concentration

-: Indicates no significant difference

Description of key information

For the target substance 2 -hexyldecanoic acid no study is available.

In a 21 d long-term Daphnia study with the analogue palmitic acid no effects were found within water solubility. The NOEC was > 0.22 mg/L.

Key value for chemical safety assessment

Additional information