Reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

other: DSH-30-3-0260-2018

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda

EC Number:

939-368-0

Cas Number:

1322-93-6

Molecular formula:

Not applicable (a generic molecular formula can not be provided for this specific UVCB substance)

IUPAC Name:

Reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Study design: in vivo (LLNA)

Vehicle:

propylene glycol

Concentration:

0, 5, 10 and 25% (w/v) in propylene glycol

No. of animals per dose:

4

Results and discussion

Positive control results:

The threshold positive value of 3 for the SI was reached in the positive control group (SI = 13.90).

In vivo (LLNA)

Results

Parameter:

SI

Value:

>= 0.92

Variability:

0.92 at 5% 1.14 at 10% 3.14 at 25%

Applicant's summary and conclusion

Conclusions:

In this study the stimulation indices (S.I.) of 0.92, 1.14 and 3.14 were determined with the test item at
concentrations of 5, 10 and 25% in propylene glycol.
As a significant lymphoproliferation (SI > 3) was noted at the concentration of 25%, the EC3 value
was determined (23.95%).
Based on the positive SI value observed at the concentration of 25%, the test material may be c
onsidered as a skin sensitiser. However, irritation was also observed at this concentration and is
known to be potentially involved in false positive lymphoproliferation responses.
Therefore, the test item may not be a skin sensitizer for the following reasons: an increase in ear
thickness was above the limit of 25% in two out of four mice (Nos. 14 and 15); the SI cut-off of 3 was
only just exceeded (SI = 3.14). Therefore it is highly likely that this weak lymphoproliferation was the
consequence of the local irritation clearly observed in 2/4 animals of this group.
Based on the results of this study, it was not possible to definitively reject the impact of irritation on
the stimulation index observed at the highest concentration, therefore it was not possible to clearly c
onclude on the potential of reaction product of naphthalene, propan-2-ol, sulfonated and neutralized
by caustic soda to induce delayed contact hypersensitivity.

Executive summary:

In order to study a possible contact allergenic potential of reaction product of naphthalene, propan-2-ol,

sulfonated and neutralized by caustic soda, a local lymph node assay (LLNA) was performed according

to the OECD Guideline 429 and under GLP regulations.

For this purpose, three groups of four female mice received the test item by topical route to the dorsal

surface of both ears on days 1, 2 and 3 at concentrations of 5, 10 or 25% (maximum technically

applicable concentration) under a dose‑volume of 25 µL. One negative control group of four females

received the vehicle (Propylene Glycol) under the same experimental conditions. Additionally, one

positive control group of 4 females received the positive control,α‑hexylcinnamaldehyde (HCA), at 25%

in a mixture acetone/olive oil (4/1; v/v) under the same experimental conditions.

From day 1 to day 3 then on day 6, the thickness of the left ear of each animal was measured, except in

animals of the positive control group and the local reactions were recorded. Each animal was observed

at least once a day for mortality and clinical signs. Body weight was recorded on days 1 and 6. After 2

days of resting, on day 6, the animals received a single intravenous injection of tritiated methyl thymidine

(3H-TdR). Approximately 5 hours later, the animals were sacrificed and the auricular lymph nodes were

excised. The proliferation of lymphocytes in the lymph node draining the application site was measured

by incorporation of3H-TdR. The results were expressed as disintegrations per minute (dpm) per group

and as dpm/node. The obtained values were used to calculate Stimulation Indices (SI). A test item is

regarded as a sensitizer in the LLNA if the exposure to one or more test concentrations resulted in 3-

fold or greater increase in incorporation of 3HTdR compared with concurrent controls, as indicated by

the stimulation index (S.I.).

No unscheduled deaths occurred and no clinical signs were observed in any animals throughout the

study. On day 6, erythema and dryness of ear skin were noted in all females treated at 25%. Erythema

was also observed in 1/4 females treated at 10%. An increase in ear thickness of 31% was observed

in females treated at 25%.

In this study the stimulation indices (S.I.) of 0.92, 1.14 and 3.14 were determined with the test item at

concentrations of 5, 10 and 25% in propylene glycol.

As a significant lymphoproliferation (SI > 3) was noted at the concentration of 25%, the EC3 value was

determined (23.95%).

Based on the positive SI value observed at the concentration of 25%, the test material may be considered

as a skin sensitiser. However, irritation was also observed at this concentration and is known to be

potentially involved in false positive lymphoproliferation responses.

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Skin sens. V1 2012 CitoxLab

Therefore, the test item may not be a skin sensitizer for the following reasons: an increase in ear

thickness was above the limit of 25% in two out of four mice (Nos. 14 and 15); the SI cut-off of 3 was

only just exceeded (SI = 3.14). Therefore it is highly likely that this weak lymphoproliferation was the

consequence of the local irritation clearly observed in 2/4 animals of this group.

Based on the results of this study, it was not possible to definitively reject the impact of irritation on the

stimulation index observed at the highest concentration, therefore it was not possible to clearly conclude

on the potential of reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic

soda to induce delayed contact hypersensitivity.