O,O-tert-butyl isopropyl monoperoxycarbonate

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:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

EC name: O,O-tert-butyl isopropyl monoperoxycarbonate
CAS no.: 2372-21-6
Water solubility: 2.2 g/L
Storage conditions: -25°C
Lot number: 1203442069
Purity: 74.6 %

Analytical monitoring:

yes

Details on sampling:

Samples were taken at the start of the test as well as after 24 hours in both old and new solutions and at the end of the test for each concentration and the control. 10 mL was sampled and pipetted directly to HPLC vials and analyzed immediately.

Vehicle:

no

Details on test solutions:

The test substance is sufficiently soluble in water to prepare a stock solution. 0.0113 g of test substance was weighed on an analytical balance at the start of the test and for the second stock 0.0116 g was weighed after 24 hours in the same manner. Each stock was then dissolved directly in approximately 100 mL of test medium. The stock solution was agitated mechanically for approximately 60 minutes to completely dissolve the test substance. The pH of the stock solution was checked and found to be 8.0 and was therefore not adjusted. After this the stock solution was filled up to exactly 100 mL with test medium.
A clear stock solution with nominal concentrations of 113 and 116 mg/L were obtained.
Further dilution of the stock solution in test medium was carried out to achieve nominal test concentrations.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test animals were taken from a Daphnia magna stock. The animals used in the test were less than 24 hours old were obtained from parent animals aged between 2-4 weeks. Daphnia were originally
obtained from Wil Research, ‘s-Hertogenbosch. The sensitivity of the Daphnia was checked by performing an inhibition test with a reference compound (potassium dichromate) twice a year. The sensitivity was tested for compliance with the relevant study guideline.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

11.5 º dH or 205 mg/L as calcium carbonate

Test temperature:

21.3 to 21.8 °C

pH:

7.8 to 8.0

Dissolved oxygen:

8.7 to 9.1 mg O2/L

Conductivity:

645 μS/cm

Nominal and measured concentrations:

Nominal concentrations: 0.3, 0.6, 1.45, 3.19, and 7.02 mg/L
Measured concentrations: nc, nc, 0.9, 1.5, 3.6 mg/L

nc: not calculated

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL glass beakers
- Type (delete if not applicable): open
- Aeration: no
- Renewal rate of test solution (frequency/flow rate): 24h
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
The test medium was Dutch Standard Water (DSW), having a pH of approximately 8.2, and a conductivity between 550 and 650 μS/cm, containing per liter of de-ionized water: 200 mg of
CaCl2•2H2O, 180 mg of MgSO4•7H2O, 100 mg of NaHCO3 and 20 mg of KHCO3.
- Culture medium different from test medium: yes

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16h light

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

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.9 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

1.5 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 3.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

EC50 was not reached (approximately 30% inhibition was observed) due to the unexpectedly low sensitivity of Daphnia magna to the test substance. The EC50 may be expressed as >3.6 mg/L, which was the geometric mean of measurements made at the highest test concentration over the test period.

Reported statistics and error estimates:

The Lowest Observed Effect Concentration (LOEC) was determined by comparison of the mobility at each concentration and the control using threshold values from the Dunnett’s test (Dunnett’s, 1955).
The No Observed Effect Concentration (NOEC) was derived from the results as the first concentration below the LOEC value, where growth shows no significant mobility inhibition relative to the control values. Confidence limits were computed on the basis of Fieller’s theorem if possible (Zerbe, 1978).
EC50 values were calculated if possible using linear interpolation. All computations were performed using Toxcalc software (Toxcalc, 1994).

Validity criteria fulfilled:

yes

Executive summary:

In order to predict the effects of the test substance in an aquatic environment, an acute immobilization test to Daphnia magna was conducted in accordance with OECD test guidelines and with the OECD Principles of Good Laboratory Practice.

The toxicity of the test chemical to juvenile daphnids was determined in a semi-static system over an exposure period of 48 hours. Nominal concentrations of 0.3, 0.6, 1.45, 3.19, and 7.02 mg/L were tested including the required control group.

A NOEC of 0.9 mg/L and a LOEC of 1.5 mg/L were determined. The EC50 (48h) may be expressed as >3.6 mg/L as 50 % effect was not reached at the highest concentration.

Geometric measured mean concentrations of all measured values was used to calculate the mean exposure for expression of the endpoints due to the recovery of the main component falling below 80% of the nominal concentrations.

The following quality criteria have been met in the present study:

· Immobilization in the control did not exceed 10%

· Oxygen concentration did not fall below 3 mg/L at any point during the study

· The EC50 value of the reference compound, potassium dichromate, was in the range of 0.25-2.0 mg/L (Documented as part of GLP laboratory maintenance).

· No daphnids were irreversibly trapped on the surface for any length of time

· Chemical analysis quality criteria were met and although the test material was not stable in the test system quantification could still be made in the region of effect allowing geometric mean concentrations to be used.

The aim of the study was to determine a concentration at which 50% effect occurs in the test organism. Due to the steep dose response when considering the range finding data this was not achieved. However due to the high sensitivity of the algae endpoint the data generated in this study is sufficient to indicate that Daphnia magna toxicity is not the driver of classification and labeling or risk assessment for this substance.

Description of key information

A valid acute Daphnia study according to OECD 202 performed under GLP is available. The test was performed semi-static with daily refreshment. The highest test concentration showed only 30% effect, so an EC50 was not reached.

A NOEC of 0.9 mg/L and a LOEC of 1.5 mg/L were determined. The EC50 (48h) may be expressed as >3.6 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

3.6 mg/L