Hydrogen trifluoromethoxyborate(1-), compound with methanol (1:1)

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

See attched justification

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

Sampling method: a portion of a reaction mixture was transferred to a standard BOD dilution bottle.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Stock solutions (0.5 to 5.0 g/L) of the test chemical were prepared in deionized water. When necessary, the stock solutions were adjusted to pH 7.5 ± 0.5 by the addition of 1N H2SO4 or 1N NaOH as required

Test organisms (species):

other: activated sludge from domestic and industrial sewage treatment plants

Details on inoculum:

Activated sludge was obtained on the day prior to the first day of each series of inhibition tests. On return to the laboratory, the solids were allowed to settle and the waste liquor was discarded. The solids were then transferred into a 9-liter laboratory-scale, semi-continuous activated sludge cylinder and diluted to approximately 8.5 liters with deionized water. The system was initially mixed by aerating at a rate of approximately 0.5 L/min, and the concentration of mixed liquor suspended solids was determined by gravimetric analysis. The solids were then allowed to settle in the cylinder and the upper layer of waste liquor was discarded. The activated sludge was washed three times with appropriate volumes of deionized water. After washing, the system was adjusted to contain 4000 ± 400 mg of mixed liquor suspended solids (dry weight) per liter. The system was then aerated continuously at a rate of 0.5 L/min and incubated at ambient temperature (21°C).
The system was supplemented daily with 50 mL of a synthetic sewage stock solution per litter of activated sludge. The synthetic sewage stock solution was composed of, per liter: Bacto-Peptone, 16.0 g; Bacto-Beef extract, 11.0 g; urea 3.0 g; K2HPO4, 28 g; MgSO4 • 7H2O, 0.2 g; CaCl2 • 2H2O, 0.4 g; and NaCl, 0.7 g. Final pH of the stock solution was adjusted to pH 7.0 with H3PO4. Fresh stock solution was prepared as required and stored for not more than two days at 5°C.
When the same source of inoculum was to be used for testing on a subsequent day (maximum of 7 days). an additional 50 mL of synthetic sewage stock solution was added per liter of activated sludge. The system was incubated overnight.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

21°C

pH:

7.4 - 8.0

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 1L-bottle, final volume 500 mL
- Aeration: 0.5 - 1.0 L/min

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water

OTHER TEST CONDITIONS
- Adjustment of pH: yes, 7.5 ± 0.5

Reference substance (positive control):

yes

Remarks:

3,5-dichlorphenol

Key result

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Details on results:

During a number of preliminary inhibition studies, it was observed that the pH of a test reaction often changed during the 3-hour incubation period. Thus, decreases in the respiration rate may have been due to a combination of both the effects of pH and toxicity of the test chemical. As a consequence, the buffering capacity of the synthetic sewage nutrient medium was increased to prevent changes in pH of reaction mixtures.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: IC50 for 3,5-dichlorphenol: 12.2 ± 2.2 mg/L (18% variance) (municipal sewage), 11.4 ± 1.5 mg/L (13% variance) (industrial sewage)

Reported statistics and error estimates:

Inhibition data were analyzed using Thompson's method of moving averages to estimate IC50 values. The experimental data were also analyzed using a probit-transformation model similar to that described by Larson and Schaeffer (1982). A nonlinear curve-fitting program (Procedure NLIN of SAS) was used to estimate IC50 values and associated 95% confidence intervals.

Cross-reference 2

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Remarks:

Source: peer review EU Risk Assessment Report

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

peer review EU Risk Assessment Report

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

not specified

Test organisms (species):

activated sludge

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

58 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Element/Boron

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

20 mg/L

Nominal / measured:

not specified

Conc. based on:

other: Element/Boron

Basis for effect:

inhibition of total respiration

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Hydrogen trifluoromethoxyborate(1-), compound with methanol (1:1)

EC Number:

220-543-9

EC Name:

Hydrogen trifluoromethoxyborate(1-), compound with methanol (1:1)

Cas Number:

2802-68-8

Molecular formula:

CH4O.CH3BF3O.H

IUPAC Name:

hydrogen trifluoro(methanolato)borate(1-) methanol (1:1)

Details on test material:

Name of the test substance used in the study report: Borfluorid-Methanol

Results and discussion

Effect concentrations

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Remarks on result:

other:

Remarks:

Value derived from effect concentrations observed in test with boric acid (value expressed as mg B/L recalculated accounting for molecular weight of the target substance)