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Toxicological information

Eye irritation

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Administrative data

Endpoint:
eye irritation: in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
No data
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP guideline study. This study is conducted on an analogue substance. Read-across is justified on the following basis: In aqueous solutions at physiological and acidic pH, low concentrations of simple inorganic borates such as boric acid, disodium tetraborate decahydrate, disodium tetraborate pentahydrate, boric oxide and disodium octaborate tetrahydrate will predominantly exist as undissociated boric acid. At about pH 10 the metaborate anion (B(OH)4-) becomes the main species in solution (WHO, 1998). This leads to the conclusion that the main species in the plasma of mammals and in the environment is un-dissociated boric acid. Since other borates dissociate to form boric acid in aqueous solutions, they too can be considered to exist as un-dissociated boric acid under the same conditions. For comparative purposes, 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. Some studies express dose in terms of B, whereas other studies express the dose in units of boric acid. Since the systemic effects and some of the local effects can be traced back to boric acid, results from one substance can be transferred to also evaluate the another substance on the basis of boron equivalents. Therefore data obtained from studies with these borates can be read across in the human health assessment for each individual substance. Conversion factors are given in the table below. This study is conducted on an analogue substance. Read-across is justified on the following basis: In aqueous solutions at physiological and acidic pH, low concentrations of simple inorganic borates such as boric acid, disodium tetraborate decahydrate, disodium tetraborate pentahydrate, boric oxide and disodium octaborate tetrahydrate will predominantly exist as undissociated boric acid. At about pH 10 the metaborate anion (B(OH)4-) becomes the main species in solution (WHO, 1998). This leads to the conclusion that the main species in the plasma of mammals and in the environment is un-dissociated boric acid. Since other borates dissociate to form boric acid in aqueous solutions, they too can be considered to exist as un-dissociated boric acid under the same conditions. For comparative purposes, 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. Some studies express dose in terms of B, whereas other studies express the dose in units of boric acid. Since the systemic effects and some of the local effects can be traced back to boric acid, results from one substance can be transferred to also evaluate the another substance on the basis of boron equivalents. Therefore data obtained from studies with these borates can be read across in the human health assessment for each individual substance. Conversion factors are given in the table below. Conversion factor for equivalent dose of B Boric acid H3BO3 0.175 Boric Oxide B2O3 0.311 Disodium tetraborate anhydrous Na2B4O7 0.215 Disodium tetraborate pentahydrate Na2B4O7•5H2O 0.148 Disodium tetraborate decahydrate Na2B4O7•10H2O 0.113 Disodium octaborate tetrahydrate Na2B8O13•4H2O 0.210 Sodium metaborate (anhydrous) NaBO2 0.1643 Sodium metaborate (dihydrate) NaBO2•2H2O 0.1062 Sodium metaborate (tetrahydrate) NaBO2•4H2O 0.0784 Sodium pentaborate (anhydrous) NaB5O8 0.2636 Sodium pentaborate (pentahydrate) NaB5O8∙5H2O 0.1832 References: WHO. Guidelines for drinking-water quality, Addendum to Volume 1, 1998.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
other: FIFRA (40 CFR 158, 162); TSCA (40 CFR 798). Although not carried out to an OECD protocol, the study has been carried out to a US EPA acceptable protocol and conducted in accordance with GLP standards (40CFR160).
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 405 (Acute Eye Irritation / Corrosion)
Deviations:
not specified
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: Boric acid
- Molecular formula: H3BO3
- Molecular weight: 61.8
- Smiles notation: B(OH)3
- Substance type: Inorganic
- Physical state: Solid
- Analytical purity: >99.9 % w/w
- Lot/batch No.: 8M8E
- Stability under test conditions: Stable
- Other: White powder and odourless

Test animals / tissue source

Species:
rabbit
Strain:
New Zealand White
Details on test animals or tissues and environmental conditions:
TEST ANIMALS
- Source: Approved USDA supplier

Test system

Vehicle:
unchanged (no vehicle)
Controls:
no
Amount / concentration applied:
TEST MATERIAL
- Amount applied: 100 mg boric acid was applied to one eye of each of 6 rabbits.
- Concentration: Boric acid used at up to 5 % in eye washes
Duration of treatment / exposure:
24 h
Observation period (in vivo):
21 days
Number of animals or in vitro replicates:
6 animals
Details on study design:
REMOVAL OF TEST SUBSTANCE
- Washing: Rinsed with physiological saline
- Time after start of exposure: 24 h


SCORING SYSTEM: According to Draize, reported as according to EU 67/548/EEC

Results and discussion

In vivo

Results
Irritation parameter:
overall irritation score
Basis:
mean
Time point:
other: Average 24, 48, 72 h
Score:
13.6
Max. score:
110
Reversibility:
fully reversible
Remarks on result:
other: Average 60 min score was 0.17
Irritant / corrosive response data:
Slightly irritating
Changes in colouration and texture of the eye and blistered appearance to conjunctiva.
Chemosis and redness reversed by seven days.
Other effects:
No data

Any other information on results incl. tables

Results of the eye irritation study:

Score (average of animals investigated)

Cornea

Iris

Conjunctiva

Redness

Chemosis

0 to 4

0 to 2

0 to 3

0 to 4

60 min

0.17

0.83

1.00

1.67

24 h

0.00

0.33

1.00

0.83

48 h

0.00

0.00

1.00

0.50

72 h

0.00

0.00

0.83

0.33

Average 24 h, 48 h, 72 h

0.00

0.11

0.94

0.56

Reversibility*

 

c

c

c

Average time for reversion

 

By 48 h

By 7 d

By 7 d

*complete

Applicant's summary and conclusion

Interpretation of results:
not irritating
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The study was performed according to FIFRA (40 CFR 158, 162); TSCA (40 CFR 7998). Minor effects on the iris and effects on the conjunctivae were reversed by Day 7. Not classifiable in the EU under directive 67/548/EEC.
Classified in US category III (40 CFR 156) "corneal involvement or irritation clearing in 7 days or less".
Non irritant under US CPS (16 CFR 15000.42).
Read-across is justified on the basis detailed in the rationale for reliability above. This study is therefore considered to be of sufficient adequacy and reliability to be used as a supporting study and no further testing is justified.