Zirconium carbide

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November 24 - December 10, 2011

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

Version / remarks:

1984

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 20031/11
- Expiration date of the lot/batch: July 31, 2012
- Purity: 99.5 %
- Appearance: dark grey powder

Analytical monitoring:

no

Details on sampling:

not applicable

Vehicle:

no

Details on preparation and application of test substrate:

- Method of application to filter paper (if used): /
- Method of mixing into soil (if used): blended in a laboratory mixer
- Method of application to soil surface (if used): /
- Controls: yes (blank control)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): /
- Concentration of vehicle in test medium (stock solution and final test solution): /
- Evaporation of vehicle before use: /

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Earthworm
- Source: Chenggong Earthworm Raising Farm, Dongli District, Tianjing, China
- Age at test initiation: adult (more than two months old with clitellum)
- Weight at test initiation: 320 - 574 mg; treatment groups: 426.8 ± 74.5 mg; control groups: 417.3 ± 69.6 mg

ACCLIMATION: 24h prior to testing

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

14 d

Test temperature:

18.56 - 19.74 °C

pH:

6.49

Moisture:

35 %
(Moisture content was detennined by drying a small sample at 105°C and re-weighing. Distilled water were added to give an overall moisture content of about 35 percent of the dry weight, and the medium were thoroughly mixed.)

Details on test conditions:

TEST SYSTEM
- Test container (material, size): height 19cm, length: 12 cm, width: 9 cm
- Amount of soil or substrate: 750 g
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control: 4
- No. of replicates per vehicle control: not applicable

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition (if artificial substrate): Sphagnum peat moss 10%; Kaolin clay 20%; Quartz sand 68%; Calcium carbonate 2%
- Pretreatment of soil: /
- Storage (condition, duration): test medium was freshly prepared on test day 0
- Stability and homogeneity of test material in the medium: no data

OTHER TEST CONDITIONS
- Photoperiod: continous lighting
- Light intensity: 675.5 to 683.3 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): behaviour, pathological symptoms, mortality

VEHICLE CONTROL PERFORMED: not applicable

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not appplicable, Limit test
- Justification for using less concentrations than requested by guideline: /
- Range finding study: yes
- Test concentrations: 1000 mg/kg soil dry weight
- Results used to determine the conditions for the definitive study: not reported

Nominal and measured concentrations:

1000 mg/kg soil dry weight (nominal)

Reference substance (positive control):

no

Key result

Duration:

14 d

Dose descriptor:

LC0

Effect conc.:

1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- Mortality at end of exposure period: 0 % in control and treatment groups
- Changes in body weight of live adults (% of initial weight) at end of exposure period: treatment group: ca. -5.1 % ; control group: ca. -5.5 %
- Morphological abnormalities: none
- Behavioural abnormalities: none
- Other biological observations: none

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Because the definitive test was a limit test, it was not necessary to calculate the LC50.

Validity criteria fulfilled:

yes

Remarks:

After the test, no death or symptoms in the control groups were noted (criterion is below 10%), the test is valid.

Conclusions:

As neither mortality nor clinical signs were observed after 14 d exposure of earthworms (Eisenia foetida) to ZrC in artificial soil, it can be concluded that ZrC is not toxic to earthworms.

Executive summary:

In a 14 day acute toxicity study, earthworms (Eisenia foetida) were exposed to nominal ZrC concentrations of 0 (control) and 1000 mg/kg dry weight of artificial soil.  The experiment was carried out in accordance with OECD Guideline 207.  The 14 day LC₅₀was > 1000 mg/kg dw of soil. The 14 day LC0 and NOEC, the latter based on behaviour and clinical signs, were 1000 mg/kg dw of soil/substrate. Thus, ZrC is considered to be non-toxic to earthworms up to/above a concentration of 1000 mg/kg dw of soil.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with earthworms according to OECD Guideline 207.

 

Results Synopsis

 

Test organism size/age: Eisenia foetida, adults

Test Type: acute toxicity

 

14 day LC₀:        1000 mg/kg dw soil

14 day NOEC:    1000 mg/kg dw soil

14 day LC₅₀:    > 1000 mg/kg dw soil

Endpoint(s) Effected:  mortaility, behaviour, clinical signs

Description of key information

In a 14 day acute toxicity study, earthworms (Eisenia foetida) were exposed to nominal ZrC concentrations of 0 (control) and 1000 mg/kg dry weight of artificial soil.  The experiment was carried out in accordance with OECD Guideline 207.  The 14 day LC₅₀was > 1000 mg/kg dw of soil. The 14 day LC₀ and NOEC, the latter based on behaviour and clinical signs, were 1000 mg/kg dw of soil/substrate. Thus, ZrC is considered to be non-toxic to earthworms up to/above a concentration of 1000 mg/kg dw of soil.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with earthworms according to OECD Guideline 207.