boron nitride (cubic)

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

boron nitride (cubic)

EC Number:

701-307-9

Cas Number:

10043-11-5

Molecular formula:

BN

IUPAC Name:

boron nitride (cubic)

Test material form:

solid: crystalline

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS- Source: Sage™ Labs, Boyertown, PA on February 15, 2011.- Age at study initiation: young adults (9-10 weeks). Females assigned to test were nulliparous and nonpregnant.- Weight at study initiation: males 228-243 grams and females 175-207 grams at experimental start- Housing: The animals were singly housed in suspended stainless steel caging with mesh floors, which conform to the size recommendations in the most recent Guide for the Care and Use of Laboratory Animals (Natl. Res. Council, 2011). Litter paper was placed beneath the cage and was changed at least three times per week.- Diet (e.g. ad libitum): Purina Rodent Chow #5012- Water (e.g. ad libitum): Filtered tap water was supplied ad libitum by an automatic water dispensing system except during exposure.- Acclimation period: 8 daysENVIRONMENTAL CONDITIONS- Temperature (°C): 20-23°C- Humidity (%): 45-60%- Photoperiod (hrs dark / hrs light): 12 hours light/dark cycle

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION- Exposure apparatus: Nose-Only Exposure Chamber (Mini-Nose Only Inhalation Chamber, ADG Developments LTD)- Exposure chamber volume: approximately 6.7 liters- Method of holding animals in test chamber: Animals were individually housed in polycarbonate holding tubes- Source and rate of air: air compressor ( JUN-AIR, Model #6-15); 28.4 Lpm- Method of conditioning air: 3.3Lpm of compressed mixing air. supplied using air from a compressed air tank (Airgas)- System of generating particulates/aerosols: modified Wright Dust Generator driven by a variable speed motor (Dayton, Model #4Z538A) D.C. speed control with 0-100 potentiometer- Method of particle size determination: eight-stage Andersen Cascade Impactor- Temperature, humidity in air chamber: 20-22 °C, 34-43%, TEST ATMOSPHERE- Brief description of analytical method used: gravimetric- Samples taken from breathing zone: yesTEST ATMOSPHERE (if not tabulated)- MMAD (Mass median aerodynamic diameter): MMAD average 2.3 µm

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

5.19 ± 0.68 mg/L

No. of animals per sex per dose:

5 female and 5 males

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days - Frequency of observations and weighing: 5 times in 14 days period- Necropsy of survivors performed: yes- Other examinations performed: body weight measured, clinical signs (daily)

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.19 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

241 min

Mortality:

all animals survived

Clinical signs:

other: There were no signs of gross toxicity, adverse pharmacologic effects or abnormal behavior.

Body weight:

Although all animals lost weight by Day 1, all animals showed a continued weight gain thereafter through Day 14.

Gross pathology:

No gross abnormalities were noted for the animals when necropsied at the conclusion of the 14-day observation period.

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated informationNo labelling requirement for acute toxicity inhalationCriteria used for interpretation of results: other: OECD GHS and CLP

Conclusions:

Under the conditions of this study, the single exposure acute inhalation LC50 of Synthetic Cubic Boron Nitride Grade 2 (2 rnicron) Powder, CAS No.: 10043-11-5 is greater than 5.19 mg,/L in male and female rats. In conformity with the criteria given in Annex VI to Commission Directive 2001/59/EC and according to Annex I of Regulation (EC) 1272/2008 and OECD-CHS (Globally Harmonized Classification System) the test item Synthetic cBN Grade 2 (2 micron) Powder has no labelling requirement for acute toxicity inhalation.

Executive summary:

An acute inhalation toxicity test was conducted with rats to determine the potential for Synthetic Cubic Boron Nitride Grade 2 (2 micron) Powder, CAS No.: 10043-11-5 to produce toxicity from a single exposure via the inhalation (nose-only exposure) route. Under the conditions of this study, the single exposure acute inhalation LC50 of the test substance is greater than 5.19 mg/L in male and female rats. After establishing the desired generation procedures during pre-test trials, ten healthy rats (5/sex) were exposed to the test atmosphere for 4 hours. Chamber concentration and particle size distributions of the test substance were determined periodically during the exposure period. The animals were observed for mortality, signs of gross toxicity, and behavioural changes at least once daily for 14 days following exposure. Body weights were recorded prior to exposure and again on Days 1,3,7 and 14 (termination). Necropsies were performed on all animals at terminal sacrifice.

All animals survived exposure to the test atmosphere. The gravimetric chamber concentration was 5.19 mg/L.

Following exposure and throughout the 14-day observation period, all animals appeared active and healthy. There were no signs of gross toxicity, adverse pharmacologic effects or abnormal behaviour. Although all animals lost weight by Day 1, all animals showed a continued weight gain thereafter through Day 14. No gross abnormalities were noted for the animals when necropsied at the conclusion of the 14-day observation period.