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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
No data
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study. Study conducted on the hydrolysis product of reference substance, boric acid.
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
Buehler test
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:
34
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
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 34.0. Group: test group. Dose level: 0.4 g 95% w/w/boric acid . No with. + reactions: 0.0. Total no. in groups: 20.0. 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.

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:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
OECD Guide-line 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:

The reference substance (BAGE) hydrolyses within less than an hour to its hydrolysis products: Boric acid and glycerol. Therefore, conducting irritation 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 skin sensitisation of boric acid has therefore been made based on available study data on boric acid.

Boric acid

Wnorowski G (1994):

OECD Guide-line 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. No animals in the test or negative control groups showed positive response for skin sensitisation. Therefore the test substance (boric acid) was considered a non-sensitiser.

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 skin sensitisation potential 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.

Supporting data:

As skin sensitisation studies are not feasible to conduct on the reference substance itself, DEREK predictions were made to assess the skin sensitisation of the reference substance itself.

No alerts were triggered by the structure of the substance, but predictions were able to be made regarding photoallergenicity and skin sensitisation.

Photoallergencity and skin sensitisation were deemed to be improbable, meaning there is at least one strong argument that the proposition is false and there are no arguments that it is true.


Migrated from Short description of key information:
A skin sensitisation test on boric acid was performed according to OECD Guideline 406 (Buehler method). Boric acid is not a skin sensitiser based on the results of this study.

Justification for selection of skin sensitisation endpoint:
Study conducted on boric acid, the hydrolysis product of the reference substance, which is of most concern to human health and is most applicable to evaluate.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:
Migrated from Short description of key information:
There is no data to suggest that boric acid is a respiratory sensitiser.

Justification for classification or non-classification

Boric acid is not a skin sensitiser.