Sodium tetrahydroborate

Endpoint summary

Description of key information

Acute oral LD50 in rats: 56.57 mg/kg
Acute dermal LD50 in rabbits: >4000 LD50 <8000 mg/kg
Acute inhalation LC0 (no lethality) in rats: >5.18 mg/L at 1 hour; converted to >1.30 mg/L, 4 hour

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 425 (Acute Oral Toxicity: Up-and-Down Procedure)

Deviations:

no

GLP compliance:

yes

Test type:

up-and-down procedure

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Ace Animals, Inc, Boyertown, Pennsylvania, USA
- Age at study initiation: 10-11 weeks
- Weight at study initiation: 196-229 g
- Fasting period before study: overnight
- Housing: one/cage in suspended stainless steel cages
- Diet (e.g. ad libitum): Purina rodent chow #5012
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 13-20 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-24 deg C
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 hours dark / 12 hours light


IN-LIFE DATES: From: July 11, 2005 To: July 25, 2005

Route of administration:

oral: gavage

Vehicle:

other: mineral oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 25% w/w suspension

Doses:

32 and 100 mg/kg

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: mortality, signs of gross toxicity, and behavioral changes during the first several hours post-dosing and at least once daily thereafter for 14 days after dosing or until death occurred.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other: Observations included gross evaluation of skin and fur, eyes and mucous membranes, respiratory, circulatory, autonomic and central nervous systems, somatomotor activity and behavior pattern. Particular attention was directed to observation of tremors, convulsions, salivation, diarrhea, and coma.

Statistics:

Not reported

Sex:

female

Dose descriptor:

LD50

Effect level:

56.57 mg/kg bw

95% CL:

ca. 32 - ca. 100

Mortality:

All animals survived at 32 mg/kg.
All animals at 100 mg/kg died within three hours of administration.

Clinical signs:

other: No effects at 32 mg/kg. Incidence of hypoactivity, hunched posture, piloerection were observed prior to death at 100 mg/kg.

Gross pathology:

No gross abnormalities were observed at 32 mg/kg.
At 100 mg/kg, intestines were extremely red.

Other findings:

none

Interpretation of results:

toxic

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute oral LD50 was determined to be 56.57 mg/kg.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

56.57 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data given

Qualifier:

no guideline available

Guideline:

other: Continuous dynamic exposure method

Principles of method if other than guideline:

A semi-portable chamber was used for exposure. An exhaust fan was utilized to provide an adjustable air flow. Test material was administered into the incoming airstream just before it entered the circular hood of the chamber.

GLP compliance:

no

Test type:

other: Continuous dynamic exposure method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 200 g
- Housing: animals were confined individually in cages constructed entirely of 3/8 inch screen to be placed into the chamber; Following exposure, five of the exposed animals and five of the control animals were placed in screen bottom cages.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: minimum of four weeks

Route of administration:

inhalation: dust

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: a semi-portable exposure chamber similar to those developed by the Public Health Service in the Taft Laboratories at Cincinnati.
- Exposure chamber volume: not reported
- Method of holding animals in test chamber: confined individually in cages constructed entirely of 3/8 inch screen and placed in a central location in the chamber
- Source and rate of air: an exhaust fan was utilized to provide an adjustable air flow through the chamber. Test material was administered into the incoming airstream just before it entered the circular hood of the chamber. Air flow was maintained at 586 liters/air.
- Method of conditioning air: not reported
- System of generating particulates/aerosols: The material was sprayed into the air stream using a Wright Dust Feeder.
- Method of particle size determination: not reported
- Treatment of exhaust air: no data
- Temperature, humidity, pressure in air chamber: not reported


TEST ATMOSPHERE
Air flow was calculated from the pressure drop across a measured inlet orifice in a steel plate. Because of the quantity of material administered, a certain amount came directly in contact with the inlet pipe and circular hood of the chamber. This material was collected, measued and the amount subtracted from the total material administered when calculating the actual exposure level. The final exposure was calculated in mg per liter by subtracting the amount recovered from upper chamber from the total amount sprayed into the chamber and dividing this difference by the total cubic feet of air circulated through the chamber.


VEHICLE
Not applicable

Analytical verification of test atmosphere concentrations:

not specified

Duration of exposure:

1 h

Concentrations:

5.18 mg/L air

No. of animals per sex per dose:

10

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days; 5 exposed and 5 control animals were sacrificed 30 minutes after completion of the exposure period. The remaining 5 exposed and 5 control animals were observed for 14 days.
- Frequency of observations and weighing: gross observation at necropsy; weighing not reported.
- Necropsy of survivors performed: yes
- Other examinations performed: histopathological: lungs and trachea removed and preserved in fixative. The lungs were inflated with fixative before removal by clamping off the trachea with a hemostat and injecting the fixative into the trachea between the hemostat and the lungs.

Statistics:

Not reported

Sex:

male

Dose descriptor:

LC50

Effect level:

> 5.18 mg/L air

Exp. duration:

1 h

Mortality:

No deaths

Clinical signs:

other: Not reported

Body weight:

Not reported

Gross pathology:

No effects

Other findings:

- Histopathology: sections of lung and trachea show no tissue pathology. Alterations seen occur in both control and test animals and not considered to be treatment related.

Interpretation of results:

practically nontoxic

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute inhalation LC50 is greater than 5.18 mg/L at 1 hour (converted to > 1.3 mg/l at 4 hours).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating conc.

Value:

1.3 mg/m³ air

Quality of whole database:

One non-guideline study did not identify an LC50, but only an LC0 at the highest technically achieved concentration (5.18 mg/l for one hour, extrapolated to 1.3mg/l for 4 hours).

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data given

Qualifier:

no guideline available

Principles of method if other than guideline:

Administered by administration under a sleeve of rubber snugly fastened about the clipped trunk of the test animal. Animals were immobilized for 24 hours immediately following treatment. At the end of the exposure period the sleeves were removed and the animals returned to cages for a 2 week observation period.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rabbit

Strain:

not specified

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Housing: individual screen bottom cages
- Weight at study initiation: 2951 - 3980 g
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: clipped trunk
- % coverage: not reported
- Type of wrap if used: rubber sleeve


REMOVAL OF TEST SUBSTANCE
- Washing (if done): no washing
- Time after start of exposure: 24 hours


TEST MATERIAL- no data



VEHICLE no vehicle

Duration of exposure:

24 hours

Doses:

1, 2, 4 and 8 g/kg

No. of animals per sex per dose:

2

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: body weight initially and once a week for two weeks
- Necropsy of survivors performed: no

Statistics:

not reported

Sex:

male

Dose descriptor:

LD50

Effect level:

>= 4 000 - <= 8 000 mg/kg bw

Mortality:

One animal died at 2000 mg/kg but this was not treatment related. All animals at 8000 mg/kg died on Day 1.

Clinical signs:

other: Skin at all application sites was completely scabbed at 24 hours with this condition still present at 14 days.

Gross pathology:

not applicable

Other findings:

not applicable

Interpretation of results:

practically nontoxic

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute dermal LD50 is between 4000 and 8000 mg/kg

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

4 000 mg/kg bw

Additional information

An acute oral toxicity study, OECD test guideline 425, in rats indicates that sodium borohydride should be regarded as toxic. Symptoms observed at the lethal dose include those considered to be agonal, observed just prior to death. At the lethal dose, it severe irritation of the gastrointestinal tract was reported, signified by reddened intestines. This is indicative of the anticipated reactivity of SBH with gastric acid to release hydrogen and generate heat. Skin at all application sites was completely scabbed at 24 hours in an acute dermal toxicity study. This condition was still present at 14 days. There was no mortality in an acute inhalation study in rats at the highest technically achievable concentration of the study.

Justification for selection of acute toxicity – inhalation endpoint
Only study

Justification for selection of acute toxicity – dermal endpoint
Only study

Justification for classification or non-classification

The test substance is classified as Category 3 based on an acute oral LD50 of 56.57 mg/kg in rats.

The test substance does not meet the CLP classification criteria for dermal or inhalation acute toxicity.