reaction mass of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-2H -isothiazol-3-one

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Rohm and Haas, Batch No. 24088

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature
- Stability under test conditions: Stable at room temperature
- Solubility and stability of the test substance in the solvent/vehicle: Soluble and stable
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: No

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Dilution in water
- Final dilution of a dissolved solid, stock liquid or gel: 0.04, 0.08, 0.12, 0.18, and 0.30 mg/L

OTHER SPECIFICS: Purity of test material was 14.17%

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Nominal (mg CMIT/MIT per liter) 0.0 (control), 0.04, 0.08, 0.12, 0.18, and 0.30
- Sampling method: TS sampling intervals: 0 and 48 h.
- Sample storage conditions before analysis: Test samples were stored in 40 mL glass bottles at 2-4 ºC and analyzed within 48 hours.

Vehicle:

yes

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnid
- Strain: Daphnia magna
- Source: In-house daphnid culture; Primary culture obtained from Aquatic Research Organisms division of Resource Analysts, Inc.
- Age at study initiation (mean and range, SD): First instar daphnids (< 24 h old)
- Feeding during test: No

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

40-48 mg/L (as CaCO3)

Test temperature:

20.0 ± 1°C (20.2 to 20.9°C)

pH:

8.0

Dissolved oxygen:

60 – 105 % of saturation, 9.1 to 9.3 mg/L

Salinity:

Not applicable

Conductivity:

1300 to 1400 µMhos/cm

Nominal and measured concentrations:

Nominal (mg CMIT/MIT per liter): 0.0 (control), 0.04, 0.08, 0.12, 0.18, and 0.30

Measured concentrations (mg CMIT/MIT per liter)
0 h 48 h Mean
0.05 0.05 0.05
0.08 0.08 0.08
0.12 0.12 0.12
0.19 0.18 0.18
0.31 0.30 0.30
The test substance was not detected in the control (analytical detection limit = 0.002 mg CMIT/MIT per liter).

Details on test conditions:

TEST SYSTEM
- Test vessel: Flow-through
- Material, size, headspace, fill volume: 19.6 liter glass aquaria containing 15 liter of test solution
- Aeration: Yes
- Type of flow-through (e.g. peristaltic or proportional diluter): Intermittent flow proportional diluter
- Renewal rate of test solution (frequency/flow rate): During the test the diluter was activated 424 times resulting in an average of 7.1 media exchanges per 24 hours.
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Filtered well water collected at Hampton, New Hampshire, USA
- Alkalinity: 154-190 mg/L (as CaCO3)
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Adjustment of pH: Not described
- Photoperiod: 16 h daylight, 8 h darkness
- Light intensity: 10 µEs-1m-2

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilisation

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

0.18 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 0.12-0.30

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.16 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 0.14-0.19

Details on results:

- Mortality of control: 95 % survival occurred in the controls.

Reported statistics and error estimates:

Probit, moving average or binomial methods were used to calculate the 24 and 48 hour median EC50 and LC50 using computer methods (Stephan C.E., 1983, Computer program for calculation of LC50, values. US EPA, Duluth, Minnesota, USA, personal communication).

Validity criteria fulfilled:

yes

Conclusions:

Based on the results of this study, a 48-h EC50 of 0.16 mg/L was determined.

Executive summary:

The 48 h NOEC was 0.12 mg CMIT/MIT per liter. No insoluble material was observed in any test vessel during the test. 

LC50 48h = 0.18 mg CMIT/MIT per liter

EC50 48h = 0.16 mg CMIT/MIT per liter

Description of key information

The results of the key study indicated that acute exposure of Daphnia magna to CMIT/MIT resulted in an EC50 of 0.16 mg/L a.i.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.16 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

0.282 mg/L