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Ecotoxicological information

Toxicity to terrestrial plants

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Endpoint:
toxicity to terrestrial plants: short-term
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
As the toxicity of cerium compounds is mainly determined by the extent to which the compound gives rise to bioavailable cerium in soil, and equally water soluble cerium compounds can be expected to give rise to similar levels of bioavailable cerium under similar conditions, terrestrial toxicity data obtained with water soluble cerium compounds can be lumped for hazard assessment purposes. In the case of cerium trinitrate, a study on the toxicity of cerium trichloride to Triticum aestivum (Hu et al., 2002) was therefore included in this dossier. This study was however performed in solution and therefore its results are only considered as supporting information. The full read across justification is attached to IUCLID Section 13.
Reason / purpose for cross-reference:
read-across source
Species:
Triticum aestivum
Duration:
16 d
Dose descriptor:
NOEC
Effect conc.:
0.5 other: mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Ce
Basis for effect:
other: primary root elongation
Remarks on result:
other: only used as supporting information
Species:
Triticum aestivum
Duration:
16 d
Dose descriptor:
NOEC
Effect conc.:
< 0.5 other: mg/L
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Ce
Basis for effect:
other: root and shoot dry weight
Remarks on result:
other: only used as supporting information
Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
No analytics were performed, therefore the study should be considered as reliable with restrictions.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Freshly emerged wheat seedlings (Triticum aestivum) were exposed to CeCl3 in a nutrient solution and the effect of Ce on plant growth was investigated during 7 or 16 days.
GLP compliance:
not specified
Analytical monitoring:
no
Details on sampling:
Plant samples were harvested (after 7 or 16 days) and washed with distilled water, then cut into shoots and roots, and the root length was measured.
Vehicle:
no
Details on preparation and application of test substrate:
no soil was used - nutrient solution experiment
Species:
Triticum aestivum
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: wheat
- Plant family: Poaceae
- Prior seed treatment/sterilization: seeds were surface sterilised with 2% NaClO for 30 min and washed thoroughly with sterilised distilled water.
Test type:
early seedling growth toxicity test
Study type:
laboratory study
Substrate type:
other: solution
Limit test:
no
Total exposure duration:
16 d
Test temperature:
not reported
pH:
5.5 +/- 0.2
Moisture:
Study performed in nutrient solution.
Details on test conditions:
TEST SYSTEM
- Testing facility: greenhouse
- Test container (type, material, size): plastic pots filled with 200 mL nutrient solution
- Amount of soil: none
- Method of seeding: pre-treated seeds placed in illuminated incubator at 25°C for germination. After two days, they began to germinate and were transplanted to nylon nets to be cultivated for 2 d.
- No. of seeds per container: not reported
- No. of plants (retained after thinning): not reported
- No. of replicates per treatment group: 3
- No. of replicates per control: 3

SOURCE AND PROPERTIES OF SUBSTRATE (if soil) - no soil used

NUTRIENT MEDIUM (if used)
- Description: modified Hoagland nutrient solution: 1 mM Ca(NO3)2, 1 mM KNO3, 1 mM KH2PO4 (replaced by 0.25 mM KCl to avoid precipitation of CePO4, KH2PO4 was applied through foliage at the end of each photoperiod), 0.5 mM MgSO4, 0.004 mM Fe-EDTA, 0.0013 mM MnSO4, 0.153 mM ZnSO4, 0.111 mM H2MnO4, 0.081 mM H3BO3, 0.064 mM CuSO4.
- Nutrient medium was changed every two days.

GROWTH CONDITIONS
- Photoperiod: 14L:10D

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): root and shoot dry weight, primary root elongation (at the end of the exposure period)
Nominal and measured concentrations:
Nominal: control + 0.5, 2.0, 10.0, 25.0 mg Ce/L
Species:
Triticum aestivum
Duration:
16 d
Dose descriptor:
NOEC
Effect conc.:
0.5 other: mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
other: primary root elongation
Species:
Triticum aestivum
Duration:
16 d
Dose descriptor:
NOEC
Effect conc.:
< 0.5 other: mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
other: root and shoot dry weight
Details on results:
7-d NOEC for root elongation = 0.5 mg Ce/L
7-d NOEC for root and shoot dry weight = 0.5 mg Ce/L
Conclusions:
In this study, the effects of cerium on wheat growth (Triticum aestivum) were investigated in a nutrient solution experiment. In the 7-d experiment, a NOEC of 0.5 mg Ce/L was obtained for primary root elongation as well as root and shoot dry weight. In the 16-d experiment, a NOEC of 0.5 mg Ce/L was obtained for primary root elongation whereas the NOEC for root and shoot dry weight was < 0.5 mg Ce/L. The results of this study were considered reliable with restrictions since no analytical verification of cerium concentrations was performed during the study. However, because the test was semi-static and at relatively low pH (5.5), precipitation of cerium may have been negligible.

Description of key information

No key data were identified for toxicity of cerium to terrestrial plants. However, further testing is not considered necessary since the current CSA performed using the equilibrium partitioning method does not indicate the need for refinement of the terrestrial hazard assessment.

Key value for chemical safety assessment

Additional information

A single reliable study was identified for toxicity of cerium to terrestrial plants (Hu et al., 2002). In this study, the effects of cerium (provided as cerium trichloride) on wheat growth (Triticum aestivum) were investigated in a nutrient solution experiment. In the 7-d experiment, a NOEC of 0.5 mg Ce/L was obtained for primary root elongation as well as root and shoot dry weight. In the 16-d experiment, a NOEC of 0.5 mg Ce/L was obtained for primary root elongation whereas the NOEC for root and shoot dry weight was < 0.5 mg Ce/L. The results of this study were considered reliable with restrictions since no analytical verification of cerium concentrations was performed during the study. However, because the test was semi-static and at relatively low pH (5.5), precipitation of cerium may have been negligible.

To get an idea of the levels of cerium in soil that would not cause any significant adverse effects on plants, the log Kp determined for soil in this dossier can be used for recalculation. A NOEC of 0.5 mg Ce/L then corresponds to a NOEC of 1733 mg Ce/kg soil dw.

A study performed in nutrient solution is not sufficient for covering this endpoint as not representative of the ‘real’ terrestrial environment. Nevertheless, further testing is not considered necessary since the current CSA, performed using the quilibrium partitioning method, does not indicate the need for refinement of the terrestrial hazard assessment.