Caesium fluoride

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to read-across justification attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

>= 408 mg/L

Conc. based on:

other: CsF

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

>= 51 mg/L

Conc. based on:

other: F-

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to read across justfication attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 90.5 mg/L

Conc. based on:

other: CsF

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 79.2 mg/L

Conc. based on:

other: Cs+

Description of key information

Based on an WoE evaluation of read-across data (CsOH and NaF) as worst case value an LC50 (96 h) of greater than 90.8 mg CsF/L is taken into account for short term toxicity to fish.

Due to the ratio of the molecular weight of cesium atoms and counter ion the values for cesium fluoride are slightly below 100 mg/L. It can be assumed that the test result does not result in classification and labelling of the substance.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

> 90.5 mg/L

Additional information

A short-term toxicity study to fish with cesium fluoride is not available. Consequently, read-across was applied using data from cesium hydroxide and sodium fluoride. CsF is not more toxic than CsOH or CsCl when comparing available study data for daphnia and algae. In addition, fish is not the most sensitive species for substances containing either cesium or fluoride ions. Therefore read across based on the two ions is in line with animal welfare and scientifically justified.

 

Short term toxicity to fish (CsOH monohydrate)

Acute toxicity of the cesium hydroxide monohydrate was assessed with acute fish toxicity test on Zebrafish (Danio rerio) over an exposure period of 96 hours in a static system. The recorded effects were mortality and symptoms of intoxication of the fish. Based on the results of a preliminary range finding test, a limit test was performed: one control and the concentration of 100 mg/L of the test item were tested according to the relevant guideline (OECD 203). Both test groups comprised seven zebrafish and 5 L test solution. No replicates were tested. The test was considered to be valid because assay acceptance criteria were fulfilled. Analytical determination of the test concentration was performed by flame photometry.

Based on the analytical results, the test concentration did not differ from the nominal concentration significantly, hence the biological results based on the nominal concentration of 100 mg/L. No mortality or clinical symptoms were observed in the control. Clinical symptoms (increased motility of operculum, unbalanced swimming, localisation under the water surface, thrashing toward the bottom) was observed on 1 fish from the 7 in the 100 mg/L test item treated group at the 24 hours observation time. Although mortality (1/7 fish) was observed on the subsequent day (at the 48 hours observation time) in this group, this was within the assay acceptance criteria (one animal can die in the control group). Hence the test was considered to be valid and the mortality observed was not taken into consideration during evaluation of the results.

Under the conditions of this acute fish toxicity study the observed endpoints for the effect of cesium hydroxide monohydrate were the following:

96h NOEC value: ≥ 100 mg test item/L;

96h LOEC value: > 100 mg test item/L and

96h LC50 value: > 100 mg test item/L.

Based on these data the calculated values of 96h-LC50, 96h-LOEC and 96h-NOEC for cesium are greater/equal or greater than 79 mg/L and for cesium fluoride are greater/equal or greater than 90.5 mg/L.

Due to the ratio of the molecular weight of cesium atoms and counter ion the values for cesium fluoride are slightly below 100 mg/L. It can be assumed that the test result does not result in classification and labelling of the substance.

 

Short term toxicity to fish (NaF)

According to the European Union Risk Assessment report (EU RAR) of hydrogen fluoride there are a number of non-standard studies available for sodium fluoride. Five short term studies with 4 different fish species were included in the EU RAR as reliable. All studies were performed in soft water.

The key value for sodium fluoride is considered to be the LC50 of 51 mg F-/L (equivalent to 408 mg CsF/L) in Onchoryhnchus mykiss published by Janssen (1989) as lowest available effect level for short term toxicity testing in fish.

 

Conclusion

It can be stated that data from CsOH reflect worst case effect levels as they result in the lowest LC50 for the registered substance CsF, and will thus be considered key value for the endpoint short term toxicity to fish.