Registration Dossier

Administrative data

Endpoint:
neurotoxicity: acute oral
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2011-06-24 to 2011-07-14
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OPPTS 870.6200 (Neurotoxicity Screening Battery)
Deviations:
no
GLP compliance:
yes
Remarks:
FIFRA standards; Code of Federal Regulations (CFR) Title 40, Part 160.
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: solution
Details on test material:
- Name of test material (as cited in study report): boric acid
- Substance type: inorganic acid
- Physical state: white, odorless, crystalline solid
- Analytical purity: 99% (56.37% B203; boron oxide)
- Purity test date: 2011-08-24
- Lot/batch No.: 8C20
- Stability under test conditions: stable

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
CMC (carboxymethyl cellulose)
Remarks:
1% (w/v)
Details on exposure:
The test substance was administered in a vehicle of 1% (w/v) aqueous carboxymethyl cellulose to Group 1and 2 animals at respective dose levels of 0 or 2000 mg/kg.
Experimental endpoints consisted of moribundity/mortality and clinical observations, body weights and body weight gains, functional observation battery and motor activity evaluations, post-fixation brain weights, and gross necropsy and neurohistopathologic observations.
Analytical verification of doses or concentrations:
yes
Frequency of treatment:
single administration
Doses / concentrations
Remarks:
Doses / Concentrations:
2000 mg/kg bw
Basis:
actual ingested
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle

Results and discussion

Effect levels

Dose descriptor:
NOAEL
Remarks:
Neurotoxicity
Effect level:
2 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'
Remarks on result:
other:

Applicant's summary and conclusion

Conclusions:
Boric acid was not neurotoxic up to 2000 mg/kg bw in rats.
Executive summary:

Boric acid was administered to male and female rats to evaluate the potential neurotoxicity of the test substance following a single oral gavage dose (followed by a 14-day observation period). The test substance was administered in a vehicle of 1 % (w/v) aqueous carboxymethyl cellulose to Group 1 and 2 animals at respective dose levels of 0 or 2000 mg/kg. Experimental endpoints consisted of moribundity/mortality and clinical observations, body weights and body weight gains, functional observation battery and motor activity evaluations, post-fixation brain weights, and gross necropsy and neurohistopathologic observations. Administration of the test substance at 2000 mg/kg resulted in no mortality or adverse clinical signs. Total body weight gain in the boric acid-treated male rats was decreased 16% compared to the control group at the end of the 14-day observation period. Functional observation battery and motor activity evaluations did not show any evidence of neurotoxicity in either sex. No neurohistopathology findings (gross lesions or treatment-related microscopic findings) were observed in either sex. In conclusion, a single oral (gavage) dose of boric acid at a level of 2000 mg/kg to male and female rats was not neurotoxic.