Trimethyl borate

Specific investigations: other studies

Administrative data

Endpoint:

specific investigations: other studies

Type of information:

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

Adequacy of study:

supporting study

Study period:

01/10/2009 to 07/12/2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: The protocol was designed based on the ASTM E981-04 (2004) method, Standard Test Method for Estimating Sensory Irritancy of Airborne Chemicals (American Society for Testing and Materials, published May, 2004).

Deviations:

not specified

Principles of method if other than guideline:

The objective of this study was to evaluate the potential for boric acid and sodium tetraborate pentahydrate to produce depression of respiratory rate resulting from airway sensory irritation when administered to male Swiss-Webster mice by whole-head (head-only) inhalation exposure. Respiratory depression may result from upper airway sensory irritation and/or pulmonary irritation.
The protocol was designed based on the ASTM E981-04 (2004) method, Standard Test Method for Estimating Sensory Irritancy of Airborne Chemicals (American Society for Testing and Materials, published May, 2004).
The respiratory depression of boric acid and sodium tetraborate pentahydrate, was evaluated in 30-minute, single-exposure study in Swiss-Webster Crl:CFW® (SW)BR mice. Boric acid was administered to several exposure levels of 4 male mice via head-only inhalation exposure as a dust aerosol at geometrically spaced concentrations.

GLP compliance:

yes

Type of method:

in vivo

Endpoint addressed:

respiratory irritation

Test material

Test material information

Constituent 1

Reference substance name:

Boric acid; Sodium tetraborate pentahydrate

IUPAC Name:

Boric acid; Sodium tetraborate pentahydrate

Details on test material:

- Name of test material: Boric acid; Sodium tetraborate pentahydrate

Test animals

Species:

mouse

Strain:

Swiss Webster

Sex:

male

Administration / exposure

Route of administration:

inhalation: dust

Vehicle:

not specified

No. of animals per sex per dose:

4 males.

Results and discussion

Details on results:

It was not possible to achieve an RD50 for boric acid or sodium tetraborate pentahydrate based on the results in the mouse sensory irritation model.

Respiratory depression expressed as group mean percent decrease from baseline respiratory rate was as follows for sodium tetraborate pentahydrate: 14%, 11%, 17%, 17%, 19%, 25%, 28%, and 33% for aerosol concentrations of 231, 186, 394, 681, 886, 798, 1442, and 1704 mg/m3, respectively. The highest concentration of sodium borate that was achievable with acceptable control of the aerosol concentration was 1735 mg/m3 with a %RD of 41 %.

Respiratory depression expressed as group mean percent decrease from baseline respiratory rate was as follows for boric acid: 9%, 21%, 15%, 14%, 18%, 8%, 15%, 15%, 19%, 19%, 21%,and 17% for aerosol concentrations of 221, 381, 436, 464, 528, 709, 650, 613, 762, 759, 1018, and 1174 mg/m3, respectively. The highest concentration of boric acid that was achievable with acceptable control of the aerosol concentration was 1096 mg/m3 with a %RD of 19 %.

Based on these results, the RD50 is > 1096 mg/m3 for boric acid, and > 1735 mg/m3 for sodium tetraborate pentahydrate.

Applicant's summary and conclusion

Conclusions:

The objective of this study was to evaluate the potential for boric acid and sodium tetraborate pentahydrate to produce depression of respiratory rate resulting from airway sensory irritation when administered to male Swiss-Webster mice by whole-head (head-only) inhalation exposure. Respiratory depression may result from upper airway sensory irritation and/or pulmonary irritation.
The protocol was designed based on the ASTM E981-04 (2004) method, Standard Test Method for Estimating Sensory Irritancy of Airborne Chemicals (American Society for Testing and Materials, published May, 2004).
The respiratory depression of boric acid and sodium tetraborate pentahydrate, was evaluated in 30-minute, single-exposure study in Swiss-Webster Crl:CFW® (SW)BR mice. Boric acid was administered to several exposure levels of 4 male mice via head-only inhalation exposure as a dust aerosol at geometrically spaced concentrations.
It was not possible to achieve an RD50 for boric acid or sodium tetraborate pentahydrate based on the results in the mouse sensory irritation model.

The highest concentration of sodium borate that was achievable with acceptable control of the aerosol concentration was 1735 mg/m3 with a %RD of 41%.

The highest concentration of boric acid that was achievable with acceptable control of the aerosol concentration was 1097 mg/m3 with a %RD of 19%.

Based on these results, the RD50 is > 1097 mg/m3 for boric acid, and > 1735 mg/m3 for sodium tetraborate pentahydrate.

The RD10 values calculated for both substances was 189 mg/m3.