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Description of key information

Boric acid was tested in a Buehler method skin sensitisation test according to OECD 406 (Wnorowski, 1994) applied at a concentration of 95 % (powder moistened with water) during both the induction and challenge phase of the test. No signs of skin sensitisation were observed. No evidence of skin sensitisation in humans exposed occupationally to borates has been reported (Bruze et al., 1995).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
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: GLP guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
Buehler test
Justification for non-LLNA method:
OECD Guide-line 406 "Skin Sensitisation" method (Buehler test ) was performed before the LLNA was set as preferred test method.
Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Davidson’s Mill Farms, South Brunswick, NJ
- Age at study initiation: Young adult
- Weight at study initiation: Males: 314 -411 g; females: 282-376 g
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
Induction: 0.4 g 95 % w/w boric acid
Challenge: 95 % w/w boric acid
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
Induction: 0.4 g 95 % w/w boric acid
Challenge: 95 % w/w boric acid
No. of animals per dose:
Test Group: 20 animals
Naive Control: 10 animals
Positive Control: 20 animals
Positive Naive Control: 10 animals
Details on study design:
MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Concentrations: 0.4 g 95 % w/w boric acid moistened with distilled water to enhance skin contact.


B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 28
- Exposure period: Test substance was wiped off with water after 6 h.
Challenge controls:
No data
Positive control substance(s):
yes
Remarks:
Dinitrochlorobenzene
Positive control results:
No data
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.4 g 95% w/w/boric acid
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
Very faint erythema seen in one animal at induction stage and 2 animals at challenge stage and also in one naïve control. No other adverse effect observed
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
0.4 g 95% w/w/boric acid
No. with + reactions:
0
Total no. in group:
20
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
no data
No. with + reactions:
10
Total no. in group:
20
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
no data
No. with + reactions:
7
Total no. in group:
20
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
20
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
20

Observations:

Treatments

Buehler test

Observations/Remarks

 

Day of treatment

 

Induction 1

day 0

Very faint erythema (0.5) observed at one test site at 24 hours after first induction dose. No other irritation observed

Induction 2

7

No irritation observed

Induction 3

14

No irritation observed

Challenge

28

No irritation observed

Scoring 1

29

Very faint erythema (0.5) observed at two test sites at 24 hours after  challenge dose. Irritation persisted at one site for 48 hours.  Very faint erythema (0.5) observed at one test site at 24 hours in one naive control.

Scoring 2

30

 

Results of skin sensitisation test:

 

Number of animals with signs of allergic reactions /
number of animals in group

 

Negative control

Test group

Positive control

scored after 24h

0 / 10

0 / 20

10/20

scored after 48h

0 / 10

0 / 20

7/20

Interpretation of results:
GHS criteria not met
Conclusions:
OECD Guideline 406 "Skin Sensitisation" method (Buehler test ) was performed using 95 % w/w boric acid moistened with distilled water to enhance skin contact. Very faint erythema was observed in one animal at induction stage and 2 animals at challenge stage and also in one naïve control. No other adverse effects were observed therefore the test substance was considered a non-sensitiser.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

A skin sensitisation test on boric acid was performed according to OECD Guideline 406 (Buehler method; Wnorowski, 1994). No sensitization studies with boric oxide were available. However, boric oxide will exhibit properties identical to those of boric acid, as it is an anhydride that will hydrolyse to give boric acid. Therefore the data for boric acid can be read across to boric oxide for acute and local toxicological effects. Please also refer to the read-across statement attached to section 13.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

There are no data to suggest that boric oxide is a respiratory sensitiser.

Justification for classification or non-classification

Boric acid is not a skin or respiratory sensitiser. In accordance with the criteria of EU Regulation (EC) No 1272/2008) boric oxide does not need to be classified and labelled as a skin or respiratory sensitizer.