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Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
03 Aug - 08 Sep 2001
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP - guideline studies

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report date:
2001

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
The Department of Health of the Government of the United Kingdom
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The in vivo test was done before LLNA, as the first-choice method for in-vivo testing, was set into force.

Test material

Constituent 1
Chemical structure
Reference substance name:
Potassium 3-sulphonatopropyl acrylate
EC Number:
250-465-0
EC Name:
Potassium 3-sulphonatopropyl acrylate
Cas Number:
31098-20-1
Molecular formula:
C6H10O5S.K
IUPAC Name:
potassium 3-(acryloyloxy)propane-1-sulfonate
Details on test material:
- Name of test material (as cited in study report): SPA, sulfopropyl acrylate
- Physical state: white powder
- Analytical purity: no data
- Lot/batch No.: 0200014/001
- Storage condition of test material: room temperature, in the dark
- pH: 5.4 in a 10% w/w aqueous solution

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: David Hall Limited, Burton-on-Trent, Staffordshire, UK
- Age at study initiation: approximately 8-12 weeks
- Weight at study initiation: 300-450 g
- Housing: animals were housed singly or in pairs in solid-floor polypropylene cages furnished with woodflakes
- Diet: Guinea Pig FD1 Diet (Special Diets Services Limited, Witham, Essex, UK), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17-23
- Humidity (%): 30-70
- Air changes (per hr): at least 15
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
water
Concentration / amount:
Intradermal induction: 0.5%
Epicutaneous induction: 75%
Challenge
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
Challenge: 75% and 50%
No. of animals per dose:
10 in test group, 5 in control group
Details on study design:
RANGE FINDING TESTS:
In the range-finding study, intradermal injections were made on the shaved shoulder of 4 guinea pigs using concentrations of 0.1, 0.5, 1 and 5% w/w in distilled water. The degree of erythema was assessed 24, 48 and 72 hours, and 7 days after the injection. The highest concentration causing mild to moderate skin irritation was selected for the intradermal induction stage of the main study. Two guinea pigs (intradermally injected with Freund's complete adjuvant 9 days earlier) were each treated with 10, 25, 50 and 75% (w/w in distilled water) solutions of the test substance. The solution was applied to clipped flanks and covered with an occlusive dressing for 48 hours. The degree of erythema and edema was assessed 1, 24 and 48 hours after exposure ended. The highest concentration causing mild to moderate skin irritation was selected for the topical induction stage of the main study. Two guinea pigs were each treated with 10, 25, 50 and 75% (w/w in distilled water) solutions of the test substance. The solution was applied to clipped flanks and covered with an occlusive dressing for 24 hours. The degree of erythema and edema was assessed 1, 24 and 48 hours after exposure ended. The highest non-irritant concentration and one lower concentration were selected for the challenge stage of the main study.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2, intradermal and epicutaneous
- Exposure period: single injection (intradermal, left and right side) and 48 hours (epicutaneous)
- Test groups:

Intradermal (3 pairs of injections, 0.1 mL):
Injection 1: a 1:1 mixture (v/v) FCA/water
Injection 2: 0.5% w/w test substance in distilled water
Injection 3: 0.5% w/w test substance in a 1:1 mixture (v/v) FCA/water
24 and 48 h after intradermal injection, the degree of erythema and edema was evaluated.

Epicutaneous:
75% w/w test substance in distilled water
On day 7 the animals were treated with a topical application of SPA. The occlusive dressing was kept in place for 48 h. The degree of erythema and edema was evaluated 1 and 24 h after removing the patch.

- Control group:
Intradermal (3 pairs of injections):
Injection 1: a 1:1 mixture (v/v) FCA/water
Injection 2: distilled water
Injection 3: distilled water in a 1:1 mixture (v/v) FCA/water
Epicutaneous: distilled water

- Site: approximately 40 mm x 60 mm area on the shoulder region
- Frequency of applications: once (intradermal and epicutaneous)
- Duration: day 0 (intradermal), day 7-9 (epicutaneous)
- Concentrations: 0.5% (intradermal), 75% (epicutaneous)

B. CHALLENGE EXPOSURE
- No. of exposures: one, topical
- Day(s) of challenge: 21
- Exposure period: 24 hours
- Test groups: test substance in distilled water
- Control group: test substance distilled water
- Site: approximately 50 mm x 70 mm, on both flanks of the animals
- Concentrations: 75% SPA on the right flank and 50% SPA on the left flank
- Evaluation (hr after challenge): 24 and 48 hours after exposure ended

OTHER: remaining test material was removed from the test site after epicutaneous exposure lasting 24 h
Positive control substance(s):
yes
Remarks:
historical data using 2-mercaptobenzothiazole and alpha-hexylcinnamaldehyde in arachid oil as positive controls was included

Results and discussion

Positive control results:
Historical data on two positive control substances (2-mercapobenzothiazole and alpha-hexylcinnamaldehyde) show that they induced positive reactions in control animals, thus meeting the reliability criteria for the GPMT. In four independent studies performed in 1999 and 2000, 2-mercapobenzothiazole induced sensitisation in 90-100% of the animals. A 5% solution was used for intradermal induction, 50% solution for topical induction, and 50% and 25% for topical challenge. In two independent studies performed in 2000 and 2001, alpha-hexylcinnamaldehyde induced sensitisation in 40% and 50% of the animals, respectively. A 5% solution was used for intradermal induction, 100% solution for topical induction, and 100% and 75% for topical challenge. See results table under 'Attached background material' (Positive control historical data).

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
50%
No. with + reactions:
9
Total no. in group:
9
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
75%
No. with + reactions:
9
Total no. in group:
9
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
50%
No. with + reactions:
0
Total no. in group:
5
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
75%
No. with + reactions:
0
Total no. in group:
5
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
50%
No. with + reactions:
9
Total no. in group:
9
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
75%
No. with + reactions:
9
Total no. in group:
9
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
50%
No. with + reactions:
0
Total no. in group:
5
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
75%
No. with + reactions:
0
Total no. in group:
5
Group:
positive control
Remarks on result:
positive indication of skin sensitisation

Any other information on results incl. tables

There were no treatment-related effects on body weight. One guinea pig in the test group was prematurely sacrificed on day 22, due to respiratory problems, weight loss and hypothermia. These effects are not considered to be treatment-related.

Slight to moderate erythema was noted at the injection sites of exposed and control animals after intradermal induction (see table 1). Following the topical induction, slight to moderate erythema and slight edema was noted at the test site in treated animals. Bleeding from the injection sites was noted in 3 treated and 2 control group animals.

The topical challenge caused positive skin responses (slight to moderate and confluent erythema with or without very slight edema) in 9/9 animals at the skin site with 75% test substance at the 24 and 48 hour time points. At the site with 50% test substance, 9/9 animals had a positive skin response (slight to moderate and confluent erythema).

Table 1: Intradermal induction, individual skin reactions

Group

Animal number

Grade of erythema at observation site

24 hours

48 hours

Left side

Right side

Left side

Right side

Test

1

1

1

0

0

2

1

1

0

0

3

2

2

1

1

4

1

2

1

1

5

1

1

1

0

6

1

1

0

0

7

1

1

1

0

8

1

1

0

0

9

1

1

1

1

10

1

1

1

1

Control

11

1

1

0

0

12

1

1

0

0

13

1

1

0

0

14

1

1

0

0

15

1

1

0

0

Applicant's summary and conclusion

Interpretation of results:
other: CLP/EU GHS Category 1A (H317) according to Regulation (EC) No 1272/2008.
Conclusions:
CLP: Skin sensitiser 1A, H317

The skin sensitisation classification category 1 for sulfopropyl acrylate (SPA-K) is based on the challenge results that all test animals (9 out of 9) gave a positive response. The classification was further specified to be 1A, based on the intradermal induction concentration. The concentration tested at intradermal induction was 0.5% SPA. As the percentage of animals with positive reaction at challenge is 100% and thus above the 60% cut-off point for classification as skin sensitiser 1A, the classification criteria are met. Therefore, classification of the test substance for skin sensitisation 1A, is justified.