Zirconium hydroxysulphate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

96 hours

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Peer reviewed research for Zr.
Sulphate is not considered sufficiently hazardous to aquatic organisms to contribute to the assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

not specified

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

Young hatchery-purchased fry (6.2 + 0.7 cm; 1.7 + 0.7 g), acclimated for at least 3 weeks to the treated city water

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

Tests were carried out using activated charcoal and ultraviolet light-treated Longueuil-city water, whose hardness generally stands between 100 to 150 mg L -I in CaCO 3 equivalents.

Test temperature:

15 +/- 0.1 deg C

pH:

pH (value not reported) was monitored periodically throughout the experiment.

Dissolved oxygen:

Aeration (7.5 cm 3 L -I min -1) of each test vessel. Dissolved oxygen (value not reported) was monitored periodically throughout the experiment.

Nominal and measured concentrations:

0 (control), 0.01, 0.1, 1, 10 and 100 mg/L Zr.

Details on test conditions:

Exposure vessels consisted of 60 L Rubbermaid containers lined with a polyethylene bag into which was placed a black-meshed Vexar (Dupont) cylinder (with lid) espousing the contour of the assay container.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 20 mg/L

Conc. based on:

element

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 50 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Registered substance

Basis for effect:

mortality (fish)

Details on results:

100% mortality within 2 hr at 100 mg/L Zr (pH-3.0), but identical effect for dilution water adjusted to pH=3.0. In the 96-hr LCs0 bioassay with rainbow trout, low pH was entirely responsible
for toxicity at 100 mg/L Zr. At 10 mg L I Zr (pH = 6.7), the next highest test concentration used in the assay, no lethal effects were observed. The LC50 was therefore initially identified as being > 10 mg L -1 Zr. However, in a subsequent sublethal bioassay carried out at 0, 1, 5 and 20 mg/L Zr, no mortality was noted at the highest concentration tested. Hence, a 96-hr LC50 > 20 mg L -1 was finally reported.

Sublethal observations / clinical signs:

The reported toxicity of zirconium 4+ ion was used to calculate the toxicity of the registered substance based on a 37% Zr w/w content

Conclusions:

The LC50 (96 hr) in rainbow trout (Salmo gairdneri) was reported to be >20 mg/L Zr, calculated to be 50 mg/l for the registered substance.

Executive summary:

The LC50 (96 hr) in rainbow trout (Salmo gairdneri) was reported to be >20 mg/L Zr. Although mortality was 100% at a higher dose of 100 mg/L Zr, this was attributed entirely to the effects of pH.

Description of key information

The LC50 (96 hr) in rainbow trout (Salmo gairdneri) was reported to be >20 mg/L Zr. Although mortality was 100% at a higher dose of 100 mg/L Zr, this was attributed entirely to the effects of pH.

The Zr4+ content of the anhydrous registered substance is ca 40%; using an assumed LC50 of 20 mg/l Zr 2 +, the product LC50 is estimated 50 mg/l

The sulphate ions will not be hazardous to aquatic organisms at this level

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

54 mg/L