Registration Dossier

Administrative data

Endpoint:
adult fish: sub(lethal) effects
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2002
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
significant methodological deficiencies
Remarks:
- The species of Yb3+ introduced as the test item is unknown. - No analytical monitoring despite the fact that "water-soluble" rare earth compounds do not dissolve easily in typical aquatic media used for ecotoxicological tests; which results in actual concentrations that are often well lower than nominal concentrations. - Not enough information about the statistical significance of the differences among treatments; thus not possible to derive NOEC for the different enzymatic endpoints. - This is a chronic study as it lasted 40 days. However, No data on the classically investigated chronic endpoints. The publication indicates that at the end of the exposure, the fish were measured but the corresponding body length data are not reported.

Data source

Reference
Reference Type:
publication
Title:
Physiological Responses of Carassius auratus to Ytterbium exposure
Author:
Guo Hongyan et al.
Year:
2002
Bibliographic source:
Ecotoxicology and Environmental Safety 53, 312}316 (2002) Environmental Research, Section B

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
- Principle of test: The purpose of the present study was to investigate the physiological responses of Carassius auratus to Yb3+ solutions of different concentration following long-term exposure. Glutamate-pyruvate transaminase (GPT), involved in body nitrogen metabolism, was studied. Antioxidant defense (SOD, CAT) and detoxifying (GST, GST-Px) enzymes were also tested so as to describe the influence of low Yb3+ exposure on C. auratus liver and to indicate the most sensitive biomonitor index of Yb3+ in aquatic ecosystems.

GLP compliance:
no

Test material

Test material form:
not specified
Details on test material:
No information are available.
Specific details on test material used for the study:
The Yb3+ compound used for the exposure is unknown. However, because HNO3 was used to maintain the pH in all test solutions, it can be suspected that fish were exposed to ytterbium trinitrate.

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
not specified

Test organisms

Test organisms (species):
Carassius auratus
Details on test organisms:
TEST ORGANISM
- Common name: Goldfish
- Source: purchased from a local aquatic research institute
- Age at study initiation (mean and range, SD): unknown
- Length at study initiation (length definition, mean, range and SD): The average body length was 8.0 cm
- Weight at study initiation (mean and range, SD): The average weight was 11.0 g
- Feeding during test: yes
- Food type: crumbled commercial assorted feed
- Frequency: once a day

ACCLIMATION
- Acclimation period: 10 days
- Acclimation conditions (same as test or not): normal conditions
- Type and amount of food: crumbled commercial assorted feed
- Feeding frequency during acclimation: once a day
- Health during acclimation (any mortality observed): mortality rate was below 1%

Study design

Test type:
semi-static
Water media type:
other: aerated test solution
Remarks:
composition not reported
Limit test:
no
Total exposure duration:
40 d

Test conditions

pH:
pH of all test solutions was maintained at 6.7 +/- 0.2 with 0.5% HNO
Dissolved oxygen:
Test solutions were aerated, but no data is available on dissolved oxygen levels
Nominal and measured concentrations:
nominal: 0, 0.01, 0.05, 0.1, 0.5 and 1.0 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass aquarium filled with 10 L of test solution
- Aeration: Yes
- Type of flow-through (e.g. peristaltic or proportional diluter): not a flow-through, but a semi-static design
- Renewal rate of test solution (frequency/flow rate): 50% of the solution was renewed daily
- No. of organisms per vessel: 6
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 6.6 g/L (considering 6 fish of a mean weight of 11 g in 10 L of exposure medium)

TEST MEDIUM / WATER PARAMETERS
No data

OTHER TEST CONDITIONS
- Adjustment of pH: Yes, pH of all test solutions was maintained at 6.7 +/- 0.2 with 0.5% HNO

EFFECT PARAMETERS MEASURED:
Some enzymatic activities were measured at the end of the 40-day exposure. For further details, see in the field "Any other information on materials and methods incl. tables".

No further data.
Reference substance (positive control):
not specified

Results and discussion

Details on results:
- Glutamate-pyruvirate transminase (GPT) enzime activity: Exposure to less than 0.01 mg/L Yb3+ solutions had no effect on GPT activity. However, exposure to low concentrations of Yb3+ solutions stimulates GPT activity in liver (P=0.05); the activation rate reached 15.2% at 0.05 mg/L Yb3+ solution. On exposure to high concentrations of Yb3+ solutions, liver GPT activity was depressed about 9% (P=0.05), occurring at 0.1 mg/L Yb3+ and remained unchanged in solutions containing more than 0.1 mg/L Yb3+.

- Superoxide dismutase (SOD) activity was stimulated when goldfish were exposed to Yb3+ solutions, and SOD activity reached the maximum of 35% (P=0.05) at 0.05 mg/L, the stimulation ratio was decreased with an increase in Yb3+ concentration.

- Catalase (CAT) enzime activity in C. auratus livers was strongly inhibited after 40 days of Yb3+ exposure; activity decreased about 30% (P=0.05) on exposure to 0.01 mg/L Yb3+.

- Glutathione peroxidase (GSH-Px) activity was stimulated about 45% at 0.05 mg/L Yb3+, whereas at Yb3+ concentrations greater than 0.1 mg/L, GSH-Px activity was reduced and not signifcantly different from that of control.

- Glutathione S-transferase (GST) activity in C. auratus liver was stimulated at low concentration and inhibited at high concentration; 0.01 mg/L Yb3+ had no effect on GST activity. A maximum increase of 38% and maximum inhibition of 30% was observed at 0.05 and 1.0 mg/L respectively.



Reported statistics and error estimates:
Indication about the statistical significance of the differences among treatments is not always available (sometimes mentioned in the publication text, but not in the figures); thus not possible to derive NOEC for the different enzymatic endpoints.

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Conclusions:
Glutamate-pyruvate transaminase (GPT) activity in goldfish liver was stimulated at 0.05 mg/L Yb3+ and inhibited at higher Yb3+ concentrations. Activity of the antioxidant enzyme superoxide dismutase (SOD) was stimulated at Yb3+ higher than 0.05 mg/L, and catalase (CAT) activity was strongly inhibited after 40 days of exposure. Detoxifying enzymes glutathione S-transferase (GST) and glutathione peroxidase (GSH-Px) were stimulated at 0.05 mg/L and inhibited at 0.1 mg/L after 40 days of exposure. Among the parameters determined, CAT in goldfish liver was most sensitive to Yb3+, indicating that CAT might be considered a potential tool in the biomonitoring of exposure to Yb3+ in an aquatic ecosystem.
Executive summary:

Carassius auratus (six fish per concentration) were exposed to Yb+3 concentrations of 0, 0.01, 0.05, 0.1, 0.5 and 1.0 mg/L (nominal). After 40 days, they were sacrificed with a scalpel. Goldfish livers were carefully isolated from adipose tissue and pancreas for analysis. The following enzyme activities were measured: glutamate-pyruvate transminase, catalase, superoxide dismutase, glutathione S-transferase and glutathione peroxidase.

Glutamate-pyruvate transaminase (GPT) activity in goldfish liver was stimulated at 0.05 mg/L Yb3+ and inhibited at higher Yb3+ concentrations. Activity of the antioxidant enzyme superoxide dismutase (SOD) was stimulated at Yb3 + higher than 0.05 mg/L, and catalase (CAT) activity was strongly inhibited after 40 days of exposure. Detoxifying enzymes glutathione S-transferase (GST) and glutathione peroxidase (GSH-Px) were stimulated at 0.05 mg/L and inhibited at 0.1 mg/ after 40 days of exposure. Among the parameters determined, CAT in goldfish liver was most sensitive to Yb3 +, indicating that CAT might be considered a potential tool in the biomonitoring of exposure to Yb3 + in an aquatic ecosystem.

Although the results of this experiment are considered not reliable due to the significant methodological deficiencies, this publication confirms that rare earth nitrates exert toxicity on fish as already showed with other soluble rare earth trinitrates.