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Description of key information

A 90 day oral feed study gave a NOAEL of 230 mg/kg bw/day Disodium tetraborate decahydrate, equivalent to 26 mg B/kg bw/day.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
sub-chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
No data
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Meets generally accepted scientific standards with acceptable restrictions.
Qualifier:
according to guideline
Guideline:
other: No data
Deviations:
not specified
Principles of method if other than guideline:
Male and female Sprague-Dawley rats were exposed daily to the test substance in the diet, which was available ad libitum. A concurrent no treatment control group was included.
GLP compliance:
no
Remarks:
Study pre-dates GLP
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Route of administration:
oral: feed
Vehicle:
not specified
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
90 Days
Frequency of treatment:
Daily; food ad lib
Remarks:
Doses / Concentrations:
0, 7.8, 23, 78 and 230 mg/kg bw/d, equivalent to 0, 17.5, 52.5, 175 and 525 ppm boron; equivalent boron 0, 0.88, 2.6, 8.8, and 26 mg B/kg bw/d.
Basis:
actual ingested
No. of animals per sex per dose:
10/sex/group
Control animals:
yes, concurrent no treatment
Details on results:
No adverse effect were observed at any dose tested.
Dose descriptor:
NOAEL
Effect level:
230 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No adverse effects were observed at any dose tested.
Dose descriptor:
NOAEL
Effect level:
26 mg/kg bw/day (nominal)
Based on:
element
Sex:
male/female
Critical effects observed:
not specified
Conclusions:
No adverse effects were observed at any dose tested.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
26 mg/kg bw/day
Study duration:
subchronic
Species:
rat

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The reference substance (BAGE) hydrolyses within less than an hour to its hydrolysis products: Boric acid and glycerol. Therefore, conducting repeat dose toxicity studies on the reference substance will give a result representative of the hydrolysis products mentioned above.

Boric acid is considered to be the hydrolysis product of main concern, due to its known toxic effects. An assessment of the repeat dose toxicity of boric acid has therefore been made based on available repeat dose study data conducted on Disodium tetraborate decahydrate.

Exposures to borates are often expressed in terms of boron (B) equivalents based on the fraction of boron in the source substance on a molecular weight basis. Only boric acid and the borate anion are present at physiologically relevant concentrations. Read- across between the different boron compounds can be done on the basis of boron (B) equivalents. It is therefore considered that the results of the study conducted on Disodium tetraborate decahydrate (expressed in boron equivalents) are appropriate in the assessment of boric acid.

Weir RJ (1963):

A 90 Day dietary administration study in rats was conducted on Disodium tetraborate decahydrate.

Male and female Sprague-Dawley rats were exposed daily to the test substance in the diet, which was available ad libitum. A concurrent no treatment control group was included. 

The test concentrations were: 0, 7.8, 23, 78 and 230 mg/kg bw/d, equivalent to 0, 17.5, 52.5, 175 and 525 ppm boron; equivalent boron 0, 0.88, 2.6, 8.8, and 26 mg B/kg bw/d.

No adverse effects were observed at any dose level tested.

Therefore the NOAEL was 230 mg/kg bw/d, equivalent boron 26 mg B/kg bw/d.

Glycerol

Glycerol is the other hydrolysis product of BAGE. It is not classified for human health according to CLP or DSD and is essentially non-toxic. Further evaluation of the repeat dose toxicity of glycerol has not been assessed.

Refer to section 13, Toxicological expert report, for further details of the evalaution of the hydrolysis of BAGE and its consequences for toxicity testing.

Justification for classification or non-classification

Boric acid is not classified for repeat dose toxicity (STOT-RE).

The available 90 day oral feed study showed no adverse effects at any dose level tested (highest test concentration 230 mg/kg bw/d, equivalent to 26 mg B/kg bw/d).

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