Zirconium dichloride oxide

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:

key study

Justification for type of information:

Read across from a study performed with zirconium dioxide. The read across justification document is attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: Zirconium dichloride oxide is not considered to be toxic or harmful to fish.

Remarks:

This conclusion was based on the results of the study from Bazzon (2000) with zirconium dioxide and the fact that zirconium dichloride oxide is not water soluble under environmentally relevant conditions and all zirconium will precipitate from solution as zirconium hydroxide / zirconium dioxide or other insoluble complexes

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

no data

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Insufficient information provided on methods and results to accurately evaluate the study.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Standard bio-assay procedure for acute toxicity to fish.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Pimephales promelas

Test type:

other: Bio-assay

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Duration:

48 h

Dose descriptor:

other: TLm - Median Tolerance Limit

Effect conc.:

17.8 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Zr

Basis for effect:

mortality (fish)

Remarks on result:

other: TLm was measured in soft water.

Duration:

48 h

Dose descriptor:

other: TLm - Median Tolerance Limit

Effect conc.:

239 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Zr

Basis for effect:

mortality (fish)

Remarks on result:

other: TLm was measured in hard water

Sublethal observations / clinical signs:

Reaction of the compound with materials present in the dilution waters, particularly in hard water, results in precipitation of insoluble compounds. This precipitation was evidenced by the formation of flocculent materials and the effect is presumed to account for much of the wide variation in the toxicities in soft and hard water. The concentration of zirconium actually remaining in solution was not measured.

Validity criteria fulfilled:

not applicable

Conclusions:

The 48h median tolerance limit in Pimephales promelas is 17.8 mg Zr/L (i.e. 56 mg/L ZrOCl2.6H2O) in soft water and 239 mg Zr/L (i.e. 750 mg/L ZrOCl2.6H2O) in hard water.

Description of key information

Read across is performed from the study from Bazzon (2000) using zirconium dioxide as test substance. In this study no effects were observed in a limit test, yielding a 96-h LC50 of > 100 mg/L (ZrO2). Read across from the insoluble zirconium dioxide to the 'water soluble' zirconium dichloride oxide is acceptable since zirconium dichloride oxide is not water soluble under environmentally relevant conditions and all zirconium will precipitate from solution as zirconium hydroxide / zirconium dioxide or other insoluble complexes.

Additional information

Two studies were available for this endpoint.

In the study of Palange et al. (1959), the 48-h median tolerance limit in Pimephales promelas was determined to be 17.8 mg Zr/L (i.e. 56 mg/L ZrOCl2.6H2O) in soft water and 239 mg Zr/L (i.e. 750 mg/L ZrCl2.6H2O) in hard water. No adjustment of pH is conducted. In soft water it is anticipated that the mortality occurred due to the low pH. In hard water the median tolerance limit is much higher and it is anticipated that this is due to the formation of a precipitate of zirconium dioxide. Due to limited information on materials and methods as well as results, the study is however not considered reliable and considered as a supporting study.

In the absence of reliable data for zirconium dichloride oxide and taking into account the behaviour of zirconium dichloride oxide in environmentally relevant aqueous media, it is considered appropriate to include the study of Bazzon (2000) as a key study. In this study the toxicity of zirconium dioxide to zebra fish (Brachydanio rerio) was studied under static conditions, according to OECD Guideline 203. Fish were exposed to control and test chemical at a nominal concentration of 100 mg/L. Mortality/immobilization were monitored daily. No mortality was observed during the test, neither in the control nor in the group exposed to the test item. The 96-h LC50 and NOEC were thus > 100 mg/L. This study result can be used for read across purposes to indicate that zirconium dichloride oxide is not toxic to fish at equivalent doses.

In conclusion, at environmentally relevant pH values, zirconium dichloride oxide can be expected not to cause any acute adverse effects in fish.