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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 29 August 2006 to 31 July 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
other: read-across target
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: triplicates samples from the test medium (loading rate of 100 mg/L) and from the control were taken just before test start and after 48 hours.
- Sampling method: no data
- Sample storage conditions before analysis: Immediately after sampling, the samples were acidified with 3% (v/v) nitric acid (HNO3, 65% Suprapur®, Merck) to stabilize the samples during the storage period. Then the samples were deep frozen and stored at about -20°C.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: an undiluted filtrate of a supersaturated dispersion with the loading rate of 100 mg/L was tested. The dispersion with the loading rate of 100 mg/L was prepared by dispersing 50.1 mg of the test item in 500 mL of test water. The test item was mixed into the test water as homogeneously as possible using ultrasonic treatment for 15 min and intense stirring. The dispersion was stirred on a magnetic stirrer at room temperature in the dark for seven days. After the stirring period, the dispersion was filtered through a membrane filter (0.45 µm). The undiluted filtrate of the dispersion was used as the test medium.
- Differential loadings: No (limit test)
- Controls: controls : blank (test water without test item)
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Strain: clone defined as clone 5
- Source: supplied in 1992 by University of Sheffield/UK
- Age at study initiation : 6-24 hours, not first brood progeny
- Weight and length at study initiation (mean and range, SD): no data
- Method of breeding: bred in RCC since 1992 in reconstituted water of the quality identical to the water used in the tests and under temperature and light conditions identical to those of the test.
- Feeding during test: No

ACCLIMATION
- Acclimation period: no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
2.5 mmol/L (= 250 mg/L as CaCO3)
Test temperature:
20°C
pH:
between 7.8 and 7.9
Dissolved oxygen:
between 8.3 and 8.6 mg/L
Salinity:
not applicable
Nominal and measured concentrations:
Nominal loading rate: 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type : 100 mL glass beakers
- Material, size, headspace, fill volume: vessels filled with 50 mL of test medium
- Aeration: 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.
- Type of flow-through (e.g. peristaltic or proportional diluter): none (static test)
- Renewal rate of test solution (frequency/flow rate): no renewal (static test)
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 2 mL of medium per daphnia

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted test water : analytical grade salts dissolved in purified water
- Alkalinity: 0.8 mmol/L
- Ca/Mg ratio (mol): 4:1 (based on molarity)
- Na/ K ratio (mol): 10:1 (based on molarity)
- Culture medium different from test medium: no
- Intervals of water quality measurement: The pH values, the dissolved oxygen concentrations and the temperature were determined at the start and at the end of the test in the control and the test medium. The appearance of the test medium was also recorded at the start of the test and after 24 and 48 hours.
- No further data

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: a 16 hour light to 8 hour dark with a 30 minute transition period.
- Light intensity: between 470 and 640 lux

EFFECT PARAMETERS MEASURED :
The daphnids were observed for immobility after 24 and 48 hours of exposure (daphnids not being able to swim within 15 seconds after gentle agitation of the test beaker are considered to be immobilized).
The NOELR and EL0 were determined directly from the raw data. The EL50 and EL100 could not be determined due to the absence of a toxic effect of the test item in this test.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not relevant (limit test)
- Range finding study: yes
- Test concentrations of the range finding study: no data
- Results used to determine the conditions for the definitive study: no mortality at the undiluted loading rate.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
The analyticaly measured concentrations of lanthanum in the test medium samples taken at the start and at the end of the test were below the LOQ (< 1 µg/L)
No remarkable observations concerning the appearance of the test medium.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- 48h-EC50: 0.67 mg/L (acceptance range : 0.53 - 1.1 mg/L) (potassium dichromate)
Reported statistics and error estimates:
None as no adverse effect was observed

Effect of LANTHANE OXYDE 99.99 OPTIQUE on the Mobility of Daphnia magna:

Treatment (Loading rate)

 

No. of

daphnids

tested

Immobilized

daphnids after

24 hours

         

 

     No.                   %

Immobilized

daphnids after

48 hours

         

 

      No.                   %

Control

20

0

0

0

0

Undiluted filtrate (100 mg/L)

20

0

0

0

0

Validity criteria fulfilled:
yes
Conclusions:
Lanthanum oxide had no acute toxic effects on Daphnia magna up to its solubility limit in the test water at the loading rate of 100 mg/L under the present test conditions.
Executive summary:

The 48hr-acute toxicity of lanthanum oxide to Daphnia magna was studied under static conditions according to the EU Commission Directive 92/69/EEC, Part C.2 (1992) and the OECD Guideline for Testing of Chemicals, N°202 (2004). Daphnids were exposed to control and test chemical at nominal concentration of 100 mg /L (loading rate) for 48 hr. Mortality/immobilization were observed daily. In the control and at the loading rate of 100 mg/L, no immobilized test organisms were determined during the test period of 48 h. Thus, the 48 hour EL50 and the 48 hour NOEC were > 100 mg/L.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted on read-across material
Justification for type of information:
Read-across to structurally similar substance, lanthanum oxide, is justified on the basis that ecotoxicological effects will be driven by the metal cation species (La3+) which is analogous to the registered substance and the read-across substance.
Reason / purpose for cross-reference:
read-across source
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility

Description of key information

48 h LL50 > 100 mg/L, 48 h NOELR >= 100 mg/L, Daphnia magna, OECD 202, EU Method C.2, RCC 2007 (read across from lanthanum oxide).  

Key value for chemical safety assessment

Additional information

The 48hr-acute toxicity of lanthanum oxide to Daphnia magna was studied under static conditions according to the EU Commission Directive 92/69/EEC, Part C.2 (1992) and the OECD Guideline for Testing of Chemicals, N°202 (2004), under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria of Klimisch (1997).

During the study, daphnids were exposed to control and test chemical at nominal concentration of 100 mg /L (loading rate) for 48 hr. Mortality/immobilization were observed daily. In the control and at the loading rate of 100 mg/L, no immobilized test organisms were determined during the test period of 48 h. Thus, the 48 hour EL50 and the 48 hour NOEC were > 100 mg/L.

No short-term toxicity data for aquatic invertebrates is available for the registered substance, lanthanum trihydroxide. A valid study has been provided on the structural analogue, lanthanum oxide. Read-across to this structurally similar substance, lanthanum oxide, is justified on the basis that ecotoxicological effects will be driven by the metal cation species (La3+) which is analogous to the registered substance and the read-across substance. The similar toxicological profiles of lanthanum oxide and lanthanum trihydroxide further substantiates this to be an acceptable read-across approach.