Calcium metaborate (Ca(BO2)2) and calcium tetraborate (CaB4O7), amorphous reaction products of boric acid with lime

Toxicity to reproduction: other studies

Administrative data

Endpoint:

toxicity to reproduction: other studies

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

No data

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Does not meet important study design or analytical criteria.

Data source

Reference

Reference Type:

publication

Title:

Effect of boric acid on the generative function in males.

Author:

Tarasenko NY, Kasparov AA & Strongina OM

Year:

1972

Bibliographic source:

Gigiena Truda y Professionalnye Zabolevaniya 16 (11): 13 - 16.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Groups of 12 male rats were exposed to aerosols of 9.6 ± 0.5mg/m3 and 48.6 ± 1.46mg/m3 boric acid for 4 hours/day for four months. When treatment was ended six males from the test and control groups were mixed (in separate cages) with an equal number of healthy oestrous females. Histological examinations of the testes were later performed.

GLP compliance:

no

Remarks:

Study pre-dates GLP.

Type of method:

in vivo

Test material

Test material information

Constituent 1

Reference substance name:

Boric acid

EC Number:

233-139-2

EC Name:

Boric acid

Cas Number:

10043-35-3

Molecular formula:

H3BO3

IUPAC Name:

Boric acid

Test animals

Species:

rat

Strain:

not specified

Sex:

male

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure (if applicable):

not specified

Vehicle:

not specified

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

4 hours per day

Frequency of treatment:

Daily

Duration of test:

4 months

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

9.6 mg/m³ air

Remarks:

aerosols of 9.6 ± 0.5 mg/m3

Doses / concentrations 2

Dose / conc.:

48.6 mg/m³ air

Remarks:

aerosols of 48.6 ± 1.46 mg/m3

No. of animals per sex per dose:

12 males per group

Control animals:

yes

Details on study design:

Groups of 12 male rats were exposed to aerosols of 9.6 ± 0.5 mg/m3 and 48.6 ± 1.46mg/m3 boric acid for 4 hours/day for four months. When treatment was ended six males from the test and control groups were mixed (in separate cages) with an equal number of healthy oestrous females. After a single and double mating vaginal smears of females were examined for spermatozoa.

Results and discussion

Effect levels

Dose descriptor:

LOAEL

Effect level:

9.6 mg/m³ air

Based on:

test mat.

Sex:

male

Basis for effect level:

other: Animals exposed to 9.6 ± 0.5 mg/m3 boric acid exhibited atrophied testis, reduced numbers and lifetime of spermatozoa, with pathological changes in the testis, including desquamation of the epithelium and necrotic cells.

Observed effects

Animals exposed to 9.6 ± 0.5 mg/m3 boric acid exhibited atrophied testis, reduced numbers and lifetime of spermatozoa, with pathological changes in the testis, including desquamation of the epithelium and necrotic cells. The effects were more severe in the 48.6 ± 1.46 mg/m3 dose group, this group also exhibiting a persistent retardation in growth as compared to the controls. Effects on the liver, kidneys, spleen and lungs were also observed.

Any other information on results incl. tables

There are a number of criticisms of this study, which prevent its use in the risk assessment of boric acid. Limitations were as follows:
1. No indication of the type of inhalation chamber is given. It was not clear as to whether exposure was to the whole body or nose only. There was no indication of aerosol size.
2. The methodology of investigation of the testis was not recognised.
3. There were no units given for spermatogenic index, nor for the numbers of spermatozoa. The term "lifetime" was not understood, and it was not clear what has been measured.
4. The histological criteria used in the table of morphological characteristics were not indicators that are normally used.

Applicant's summary and conclusion

Conclusions:

Animals exposed to 9.6 ± 0.5 mg/m3 boric acid exhibited atrophied testis, reduced numbers and lifetime of spermatozoa, with pathological changes in the testis. The effects were more severe in the 48.6 ± 1.46 mg/m3 dose group. However, there were a number of limitations relating to the methodology and reporting.