1,2-dihydro-3H-1,2,4-triazol-3-one

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

September 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

ISO 10253 (Water quality - Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactylum tricornutum)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test substance: Triazolone
CAS#: 930-33-6
Stability: stable
Solubility: soluble in seawater
Appearance: white solid, powder with no odour
Date received: 01.09.2006
Storage: 20°C

Analytical monitoring:

not specified

Details on sampling:

none

Vehicle:

no

Details on test solutions:

Dissolve the test substance in the culture medium. The concentration of this stock solution should correspond with the highest test dosage.
Mix the stock solution in a 1L glassflask on a magnetic stirrer for at least 30 min.

Based on the results from the preliminary test, the following test dosages were used for the definitive test: 2.0, 10, 50, and 250 mg/L

Test organisms (species):

Skeletonema costatum

Details on test organisms:

Strain NIVA BAC 1 was used.

Test type:

static

Water media type:

saltwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

not specified

Test temperature:

20 +/- 2.4 °C

pH:

7.5 - 8.3

Salinity:

NA

Conductivity:

not specified

Nominal and measured concentrations:

nominal concentrations: 2.0, 10, 50, and 250 mg/L

Details on test conditions:

Two tests were performed. A preliminary test with 2 parallel test concentrations, followed by a definitive test wtih 3 parallel concentrations and 6 controls.
Inhibition is measured as a reduction in growth rate relative to control cultures grown under identical conditions.
light intensitiy has been in the range 6000-10000 lux.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

none

Results with reference substance (positive control):

growth rate inhibition of 1.5 mg/L 3,5-dichlorophenol = 24%

Reported statistics and error estimates:

none

none

Validity criteria fulfilled:

yes

Conclusions:

The 72hEC50 for triazolone was found to be 18 mg/L.
The NOEC value was estimated to 2.0 mg/L.

Executive summary:

S. costatum testing has been performed on the test substance TO Triazolone base on ISO 10253.

The EC50 -value found for the test substance TO Triazolone (nominal whole product) after 72h was 18 mg/L. The EC10 was estimated to 4.2 mg/L, and the NOEC value was estimated to 2.0 mg/L.

Description of key information

Data based on experimental study results.

S. costatum testing has been performed on the test substance TO Triazolone base on ISO 10253.

The EC50 -value found for the test substance TO Triazolone (nominal whole product) after 72h was 18 mg/L. The EC10 was estimated to 4.2 mg/L, and the NOEC value was estimated to 2.0 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

18 mg/L