1H-Imidazole, hydrobromide (1:1)

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

2004-12-14 to 2005-02-12

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Read-across from imidazole hydrobromide to imidazole hydroiodide is justified since both substances only differ in the respective counterion iodide or bromide. Both anions iodide and bromide are quite similar concerning ecotoxicological behaviour and thus do not influence the ecotoxicological results received.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

Part I (1984)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

(1992)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed March 2003

Test material

Test material information

Constituent 1

Reference substance name:

1H-Imidazole hydroiodide

Cas Number:

68007-08-9

Molecular formula:

C3H4N2*HI

IUPAC Name:

1H-Imidazole hydroiodide

Test material form:

solid

Details on test material:

- Name of test material (as cited in study report): Imidazolhydroiodid
- Solubility in water: > 500 g/L
- pH in aqueous solution: 3.5 - 4.5 at concentrations of 50 g/L

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature, protected from light

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Duplicates of test media samples from nominal concentrations of 0.46 to 4.6 mg/L were measured.
- Sampling method: HPLC-UV/VIS
- Sample storage conditions before analysis: all samples were deep-frozen at -20 °C

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution (10 mg/L) was prepared in test water using intense stirring for 10 minutes at room temperature. Lower test concentrations were prepared by dilution.
- Differential loading: 6 dilutions of the stock solution were prepared with a spacing factor of approx. 2.2.
- Controls: Test medium without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): None, all solutions were clear throughout the test.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain/clone: Daphnia magna Strauss Clone 5
- Source: Laboratory culture
- Age of parental stock (mean and range, SD): less than 24 hours
- Feeding during test: None

ACCLIMATION
Not applicable.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

2.5 mmol/L (= 250 mg/L as CaCO3)

Test temperature:

20 °C

pH:

7.6 to 7.9

Dissolved oxygen:

> 8.6 mg/L throughout the test

Salinity:

not applicable

Conductivity:

no data

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 0.1, 0.22, 0.46, 1.0, 2.2, 4.6, and 10 mg/L corresponding to:
mean measured concentrations: not detected, not measured, not measured, 0.463 mg/L, 0.992 mg/L, 2.27 mg/L, 4.68 mg/L, not measured, corresponding to a mean recovery of 99 to 103 % of nominal concentrations.

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL glass beakers
- Type (delete if not applicable): covered with glass plates
- Material, size, headspace, fill volume: glass, 100mL, filled with 50 mL test medium
- Aeration: only prior to the test start
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 1 daphnid per 5 mL

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water according to OECD 202
- Intervals of water quality measurement: At test start and end , the pH, the dissolved oxygen and the water temperature was determined in each test concentration and the control.

OTHER TEST CONDITIONS
- Photoperiod: 16/8 h light/dark cycle
- Light intensity: 570 - 740 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- immobilisation after 48 h


RANGE-FINDING STUDY
Test concentrations were based on the results of a range-finding test (without GLP).

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(analytically verified)

Basis for effect:

mobility

Remarks on result:

other: 95% CL 1.3 to 1.6 mg/L

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Remarks:

EC0

Effect conc.:

0.46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(analytically verified)

Basis for effect:

mobility

Effect concentrations 3

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

4.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(analytically verified)

Basis for effect:

mobility

Details on results:

- Mortality of control: None

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 48-h EC50: 0.55 - 1.1 mg/L (historical data from 1996 to 2004)
- Dose-response test: yes
- EC50: 0.83 mg/L

Reported statistics and error estimates:

The 24-hour and 48-hour EC50 and the 95% confidence limits were estimated by Probit Analysis

Any other information on results incl. tables

Table 1: Biological test results

Parameter	Test item concentration (nominal) [mg/L]
24-hour EC50: 95% confidence limits:	1.8 1.6-2.0
24-hour EC0:	1
24-hour EC100:	4.6

Table 2: Results obtained for the concentrations of the test item in the test medium

Nominal concentration of test item [mg/L]	Test item measured (average)
	[mg/L]	[% of nominal]
Treatment samples
0.46	0.463	101
1.0	0.992	99
2.2	2.27	103
4.6	4.68	102
Biological control sample
0	n.d.	n.a.
Spiked test water samples
0.396	0.433	109
7.92	8.02	101
mean:		105
Analytic blank
0	n.d.	n.a.

n.d. = no test item detected; n.a. = not applicable

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Validity criteria of updated version of OECD 202 (2004) were also met.

Conclusions:

In a short-term toxicity test according to OECD 202, mobility of juvenile Daphnia magna was affected by imidazol hydroiodide; the respective 48-h EC50 amounts to 1.4 mg/L with a corresponding 48-h NOEC value of 0.46 mg/L (all nominal, analytically verified).