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

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Similar to all coordination complexes of boron trifluoride with organic and inorganic species (like alcohols, ethers, amines, sulfuric acid, sulfuric dioxide, etc) the complex of boron trifluoride and methanol is extremely water sensitive and reacts even with moist air. Given the extremely rapid decomposition the rate of hydrolysis cannot be quantitatively derived in a study conducted according to OECD Guideline 111. However sufficient information is available on the identity of hydrolysis products which aquatic organisms may be eposed.
In the instantaneous reaction with water as a first step methanol and boron trifluoride dihydrates are formed.
BF3·CH3OH+ 2 H2O -> BF3· 2 H2O + CH3OH
The hydrolysis of borontrifluoride dihydrate was investigated at pH-values of 1.2; 4.0; 7.0 and 9.0 (BASF SE, Study No. 09S01179, 26.19.2009)
The hydrolysis of the test item is a very fast process (half-life < 30 minutes). Already at room temperature about 30 to 60% of the test item was hydrolyzed within minutes in all tested buffer solutions in the pH range 1.2 to 9.0.
The main reactions of the hydrolysis process are the following:
BF3.2H2O + H2O → B(OH)3+ 3HF
HF + BF3.2H2O → HBF4+ 2H2O
B(OH)3+ 4HF → HBF4+ 3 H2O
HBF4+ H2O ↔ HBF3(OH) + HF
Total hydrolysis of HBF4:
HBF4↔ HBF3(OH) ↔ HBF2(OH)2↔ HBF(OH)3↔ HB(OH)4= B(OH)3+ H2O
Boric acid and tetrafluoroborate are expected to be the main species in the dilute hydrolysis solution (Zhang Weijiang et al.).
In conclusion it is justified to base the assessment of environmental fate and pathways of hydrogen trifluoromethoxyborate (1-), compound with methanol (1.1) on the properties of the breakdown products, which is considered acceptable in accordance with REACH Annex XI, section 1.5.
References:
BASF SE, Boron trifluoride dihydrate: hydrolysis as a function of pH, Study No. 09S01179, 26.10.2009
Wamser C. A. Equilibria in the system boron trifluoride-water at 25 °C,Journal of the American Chemical Society, 1951, 73: 409-416
Zhang Weijiang et al., Equilibrium on the hydrolysis of Boron trifluoride in large amount of water,Transactions of Tianjin University, 2016, 22: 486-491


2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
boron trifluoride dihydrate (CAS no. 13319-75-0), methanol (67-56-1). For purity and impurities see study records in IUCLID chapter 7.5.2.

3. ANALOGUE APPROACH JUSTIFICATION
The hydrolysis data in IUCLID chapter 5.1.2 demonstrate the rapidity of the hydrolysis reaction. Exposure will never occur to the complex of boron trifluoride methanol but to its hydrolysis products, BF3 dihydrate and methanol. Therefore, these two substances are the relevant ones for evaluation of potential health effects.

4. DATA MATRIX
A data matrix is not applicable in this case. The present read-across approach is not based on the comparison of experimental data for one or more compounds, but the hydrolysis products of the registered material are considered the relevant toxophors due to the rapid hydrolysis reaction. Reliable data are provided for all hydrolysis products, whereby an evaluation of potential health hazards can be performed.

Cross-reference

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

other: not specified

Principles of method if other than guideline:

Daily application of a single dose of methanol to monkeys by gavage over a period of 3 days.

GLP compliance:

not specified

Limit test:

no

Species:

monkey

Strain:

not specified

Sex:

male

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 30 % solution
- Amount of vehicle (if gavage): no data

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

3 days

Frequency of treatment:

daily

Dose / conc.:

2 340 mg/kg bw/day (nominal)

Remarks:

Basis: actual ingested

No. of animals per sex per dose:

7 males

Control animals:

not specified

Clinical signs:

no effects observed

Mortality:

mortality observed, treatment-related

Description (incidence):

2340 mg/kg bw was the lethal dose for all 7 animals after 3 days.

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Immunological findings:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Neuropathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Key result

Dose descriptor:

LOAEL

Effect level:

2 340 mg/kg bw/day (actual dose received)

Sex:

male

Basis for effect level:

mortality

Key result

Critical effects observed:

no

2340 mg/kg bw was the lethal dose for all 7 animals under test after 3 days.

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)

Results and discussion

Effect levels

Dose descriptor:

LOAEL

Effect level:

2 340 mg/kg bw/day (actual dose received)

Sex:

male

Basis for effect level:

mortality

Target system / organ toxicity

Critical effects observed:

not specified