(hydroxyethyl)urea

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study in accordance with OECD TG 406

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

in vivo skin sensitisation study was carried out or initiated before the entry into force of the amendments to Annex VII

Test material

Test material information

Constituent 1

Reference substance name:

EXP 3982 N-2-hydroxethylurea

IUPAC Name:

EXP 3982 N-2-hydroxethylurea

Details on test material:

- Name of test material (as cited in study report): EXP 3982 N-2-hydroxyethylurea
- Physical state: clear yellow liquid
- Analytical purity: aqueous solution containing 57.58% hydroxyethyl urea
- Impurities (identity and concentrations): not reported
- Composition: aequeous solution containing 57.58% hydroxyethyl urea
- Purity test date: not reported
- Lot/batch No.: 84714
- Expiration date of the lot/batch: 15 July 2001
- Storage condition of test material: at room temperature

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Hilltop Lab Animals, Inc., Scottdale, PA
- Age at study initiation: males: 8 weeks, females: 9 weeks
- Weight at study initiation: males: 424 - 500 g, females: 385 - 474 g
- Housing: individually in suspended stainless steel cages
- Diet (e.g. ad libitum): PMI Certified Guinea Pig Chow #5026 (Purina Mills, Inc.) ad libitum
- Water (e.g. ad libitum): municipal tap water treated by reverse osmosis ad libitum
- Acclimation period: acclimated to the laboratory conditions for a minimum of five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20- 24
- Humidity (%): 42 - 55
- Air changes (per hr): 10 - 15
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

unchanged (no vehicle)

Induction 2

Concentration / amount:

Day 0, intradermal induction: 5%
Day 7, topical induction: 100%
Day 20, challenge: 100%

Challenge

Challenge 1

Route:

other:

Vehicle:

unchanged (no vehicle)

Challenge 2

Concentration / amount:

Day 0, intradermal induction: 5%
Day 7, topical induction: 100%
Day 20, challenge: 100%

No. of animals per dose:

Test group: 10 males, 10 females
Control group: 5 males, 5 females

Details on study design:

RANGE FINDING TESTS:
- Topical range-finding study: The results of the range-finding study indicated that a test article concentration of 100% (as received) was appropriate for topical induction and challenge. This was the highest possible concentration which did not produce any significant skin irritation.
- Interdermal range-finding study: The results of the range-finding study indicated that a test article concentration of 5.0% w/v in deionised water was appropriate for intradermal induction since mild skin irritation was observed at this concentration. While there were some unexpectedely high range-finding scores at the lower concentrations, these differences were not sufficient to warrant dosing at a lower concentration.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2
- Exposure period: 48 h (topical induction)
- Test groups: Intradermal induction: 0.1 mL of FCA emulsion, 0.1 mL of 5.0% w/v EXP 3982 N-2-hydroxyethylurea/deionised water, 0.1 mL of 5.0% w/v EXP 3982 N-2-hydroxyethylurea/FCA emulsion. Topical application: 0.8 mL pure test material
- Control group: Intradermal induction: 0.1 mL of FCA emulsion, 0.1 mL of deionized water, 0.1 mL of 5.0% w/v deionized water/FCA emulsion.
- Site: scapular area
- Frequency of applications: interdermal induction on day 0, topical induction on day 6
- Duration: topical application: 48 h
- Concentrations: 5% for intradermal induction, 100% for topical induction

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 1
- Exposure period: 24 h
- Test groups: 0.3 mL pure test substance
- Control group: 0.3 mL pure test substance
- Site: scapular area
- Concentrations: pure test substance
- Evaluation (hr after challenge): 24 and 48

Positive control substance(s):

yes

Remarks:

alpha-Hexylcinnamaldehyde

Results and discussion

Positive control results:

Using alpha-Hexylcinnamaldehyde (HCA) as a positive control, Springborn Laboratories, Inc., Spencerville, Ohio, had completed a study dwhich provided historical control data for contact sensitisation to this agent utilising the test system described herein (Maximisation Design). Following intradermal induction at 5.0% w/v HCA in propylene glycol, topical induction at 5.0% w/v HCA in propylene glycol and challenge at 0.5% and 1% w/v HCA in propylene glycol, a contact sensitisation response was observed, thereby demonstrating the susceptibility of the test system to this sensitising agent.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.3 mL

No. with + reactions:

1

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.3 mL. No with. + reactions: 1.0. Total no. in groups: 20.0.

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.3 mL

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.3 mL. No with. + reactions: 0.0. Total no. in groups: 20.0.

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0.3 mL

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0.3 mL. No with. + reactions: 0.0. Total no. in groups: 10.0.

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0.3 mL

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0.3 mL. No with. + reactions: 0.0. Total no. in groups: 10.0.

Any other information on results incl. tables

Noticeable irritation outside of test site was observed in the test group and the negative control group probably due to the binding tape material. The reactions do not interfere with the scoring of the test site.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Based on the results of this study, EXP 3982 N-2-hydroxyethylurea is not considered to be a contact sensitizer in guinea pigs.

Executive summary:

The dermal sensitisation potential of EXP 3982 N-2-hydroxyethylurea containing 57.58% of the active ingredient hydroxyethyl urea was evaluated under GLP in Hartley-derived albino guinea pigs according to OECD TG 406. Ten male and ten female guinea pigs received intradermal injections of 5.0% w/v EXP 3982 N-2-hydroxyethylurea in deionised water along with injections of FCA and 5.0% w/v EXP 3982 N-2-hydroxyethylurea in FCA. One week later, the test animals received a topical application of 100% (as received) EXP 3982 N-2-hydroxyethylurea. Challenge and rechallenge control animals received similar intradermal and topical treatments with deionised water that was used in place of the test article.

Following a two-week rest period, a challenge was performed whereby the twenty test and ten challenge control guinea pigs were topically treated with 100% (as received) EXP 3982 N-2-hydroxyethylurea. Challenge responses in the test animals were compared with those of the challenge control animals. Following challenge with 100% (as received) EXP 3982 N-2-hydroxyethylurea, dermal scores were limited to 0 in the test and challenge control animals at the 24- and 48-hour scoring intervals with the exception of one ± at 24 hours. Group mean dermal scores were noted to be 0.0 in both the test and challenge control animals.

Using alpha-Hexylcinnamaldehyde (HCA) as a positive control, Springborn Laboratories, Inc., Spencerville, Ohio, had completed a study which provided historical control data for contact sensitisation to this agent utilising the test system described herein (Maximisation Design). Following intradermal induction at 5.0% w/v HCA in propylene glycol, topical induction at 5.0% wlv HCA in propylene glycol and challenge at 0.5% and 1% w/v HCA in propylene glycol, a contact sensitisation response was observed, thereby demonstrating the susceptibility of the test system to this sensitising agent.

Based on the results of this study, EXP 3982 N-2-hydroxyethylurea is not considered to be a contact sensitizer in guinea pigs. The results of the HCA positive historical control study demonstrated that a valid test was performed and indicated that the test design would detect potential contact sensitizers. Hydroxyethyl urea is therefore not classified as a skin sensitiser by GHS criteria.