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

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.89 mg/m³

Most sensitive endpoint:

irritation (respiratory tract)

Route of original study:

By inhalation

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

6

Dose descriptor starting point:

NOAEC

Value:

6 mg/m³

Modified dose descriptor starting point:

NOAEC

Value:

4.02 mg/m³

AF for dose response relationship:

1

Justification:

Starting point=NOAEC

AF for differences in duration of exposure:

2

Justification:

Default assessment factor, extrapolation from sub-chronic to chronic

AF for interspecies differences (allometric scaling):

1

Justification:

No allometric scaling has to be applied in case of inhalation to inhalation route to route extrapolation.

AF for other interspecies differences:

1

AF for intraspecies differences:

3

Justification:

Default assessment factor for workers decreased from 5 to 3 because no differences will be expected (no enzyme polymorphisms exist)

Justification:

1

Acute/short term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1.9 mg/m³

Most sensitive endpoint:

irritation (respiratory tract)

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.89 mg/m³

Most sensitive endpoint:

irritation (respiratory tract)

Acute/short term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1.9 mg/m³

Most sensitive endpoint:

irritation (respiratory tract)

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

high hazard (no threshold derived)

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

high hazard (no threshold derived)

Additional information - workers

 

Long term, inhalation DNEL (workers)

The toxicological effects of boron trifluoride methanol are basically driven by the toxicological properties of BF₃which is released from hydrolysis of this adduct in aqueous media. Hence, for the DNEL it is proposed to overwrite the DNEL of BF₃or rather BF₃dihydrate on a molar ratio.

The subchronic study performed by Rusch et al. (1986) was considered as the study in which exposure was probably best reflecting occupational exposure conditions. In this study (Rusch et al., 1986), rats were exposed to aerosols of BF₃dihydrate for 13 weeks, the NOAEC was set at 6 mg/m³based on the occurring kidney effects. Clinical signs of respiratory irritation were seen at all dose levels, but without abnormal histological findings. In addition, necrosis of the renal tubular epithelium could be detected.

For the derivation of the long-term DNEL, the starting point had to be modified according to Chapter R.8 of the REACH Guidance. Here, a correction for activity driven differences of respiratory volumes in workers compared to workers in rest was added to receive a starting point of 4.02 mg/m³. Additionally, an overall assessment factor of 6 was established: 2 for time extrapolation and 3 for intraspecies variability. The latter factor is lower than the default factor of 5 since the effects were considered to be mainly due to unspecific chemical reactivity of BF₃and hydolysis to degradation products. No enzyme polymorphism is expected to be involved. No interspecies factor was used since the exposure route of the experimental study was inhalation. Thus, applying these assessment factors, a health-based occupational exposure limit of 0.7 mg/m³was recommended for BF₃dihydrate. Based on the molar ratio of 1:1.27 (131.81 g/mol / 103.81 g/mol), an exposure limit of 0.89 mg/m³was calculated for boron trifluoride methanol which is supposed to cover both local and systemic effects.

Description	Value	Remark
Step 1) Relevant dose-descriptor	NOAEC: 6 mg/m^3
Step 2) Modification of starting point	× 6.7 m^3/10 m^3	According to Chapter R.8 of REACH Guidance, correction for activity driven differences of respiratory volumes in workers compared to workers in rest.
Modified dose-descriptor	6 * 0.67 =4.02 mg/m^3
Step 3) Assessment factors
Interspecies	1	No allometric scaling has to be applied in case of inhalation to inhalation route to route extrapolation.
Intraspecies	3	Default assessment factor for workers decreased from 5 to 3 because no differences will be expected (no enzyme polymorphisms exist)
Exposure duration	2	Default assessment factor, extrapolation from sub-chronic to chronic
Dose response	1	Starting point=NOAEC
Quality of database	1
DNEL BF3 2*H2O	4.02 / (1 × 3 × 2 × 1 × 1) =0.7 mg/m^3
DNEL boron trifluoride methanol	0.7 * 1.27 =0.89 mg/m^3(Mol: BF3 2*H2O=103 boron trifluoride methanol  = 108.1àratio 1:1.27)

Short term inhalation DNEL (workers)

For the short-term DNEL of BF₃the German OEL of 1 mg/m³has been employed with the following rationale: the ECHA guidance authorizes a registrant to use a national OEL instead of deriving a DNEL in case where toxicological information and evaluations of health effects used for setting the national OEL are documented and available. Therefore, it is proposed to use the German OEL (1 mg/m³for BF₃, equivalent to 1.5 mg/m³for BF₃dihydrate) (http://www.baua.de/cae/servlet/contentblob/664358/publicationFile/47955/900-bortrifluorid-dihydrat.pdf) in place of the derivation of the DNEL. This OEL value is the lowest occupational exposure level in Europe, and is based on available and relevant toxicological data at present.

For hydrogen trifluoromethoxyborate(1-), compound with methanol(1:1)an equimolar DNEL of 1.9 mg/m³ is proposed.

 

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Additional information - General Population

There are only industrial uses for boron trifluoride methanol. The rejects of the substance in the environment (water, air) is extremely low. General population is not exposed via inhalation, dermal or oral route. Therefore no DNEL is calculated for the general population.