2-tert-butyl-1,4-dimethoxybenzene

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Remarks:

Draize repeated insult technique

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 April - 24 May 1971

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1971

Report date:

1971

Reference 2

Reference Type:

review article or handbook

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Draize technique

Deviations:

no

Principles of method if other than guideline:

The study was conducted to ascertain irritative and sensitising potential of Vetimoss in human volunteers using a repeated insult method (Draize technique) approved by US FDA. Volunteers were exposed to 0.5 mL of test material (8 formulations) in closed patches for 22 days (repeated applications 10 x 48h, except after the first and last exposure 24h, and 72h on weekends). After a rest period of 13 days, challenging test patches were applied in dublicate for 48h. Second reading was made after 144h.

GLP compliance:

no

Type of study:

Draize test

Justification for non-LLNA method:

The substance has been tested in human volunteers using a Draize test in 1971, and the study is well-conducted and -reported.

Test material

Test material information

Constituent 1

Reference substance name:

2-tert-butyl-1,4-dimethoxybenzene

EC Number:

244-216-5

EC Name:

2-tert-butyl-1,4-dimethoxybenzene

Cas Number:

21112-37-8

Molecular formula:

C12H18O2

IUPAC Name:

2-tert-butyl-1,4-dimethoxybenzene

Test material form:

liquid

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Test material: Vetidrone (identified as Vetimoss by The Research Institute for Fragrance Materials, RIFM)
- Preparations codes: Giv 1-0295, 1-1282, 1-1286, 1-1449, 1-1581, 1-1639, 2-2591 and 3-1590
- Source and lot/batch No.of test material: not specified
- Expiration date of the lot/batch: not specified
- Purity: not specified

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: test sample was prepared as 2.0% solution in dimethyl phthalate

In vivo test system

Test animals

Species:

other: Human

Sex:

male/female

Details on test animals and environmental conditions:

- 58 volunteers (age 17-64) were enrolled into the study. 53 completed the sensitisation and challenge test studies, consisting of 39 females and 14 males.
- Justification for the large number of volunteers: to ensure the completion of the entire investigation by at least the desired fifty people, taking into consideration the anticipated loss or elimination of some of the subjects due to various personal reasons or irritations from the adhesive tape or other sources resulting from repeated applications and removals of the patch tests.
- The volunteers were chosen on a random basis in order of their applying for participation to the study and subjects with active dermatologic conditions or other discernible illnesses were excluded.
- Any previous sensitivities or history of allergy were not considered to be reasons for rejection, but were noted as key information that could be useful when interpreting the results.

Study design: in vivo (non-LLNA)

Induction

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

0.5 mL

Day(s)/duration:

48h

Adequacy of induction:

not specified

Challenge

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

0.5 mL

Day(s)/duration:

48h

Adequacy of challenge:

not specified

No. of animals per dose:

58 (53 completed both sensitisation and challenging tests)

Details on study design:

PROCEDURE
- Type of method: repeated insult method approved by the Food and Drug Administration, known as the Draize technique.
- The procedure involves repeated cycles of applying close patch tests with 0.5 mL of each test solution applied to individual absorbent patches. One preparation was made to each specific patch.
- The patches were applied to the skin area in a definite fixed sequence, which was identically followed at each testing site.
- The patches were secured by overlapping stripes of impervious adhesive tape, which were further occluded with additional overlying strips of similar tape.
- The patches were left in situ for 48 hours. Exceptions include patches left in situ for 72 hours over the weekend until the following Monday and the first patch applied is removed after 24 hours to check for primary signs of irritation before proceeding with full length test exposures.
- Once the patches were removed, similarly prepared patches were applied to the next area in the identical sequence with identical occlusive precautions.

TEST SITE
- The application site was cleansed with an ether-acetone mixture to remove any sebum or foreign material such as powders or bath oils.
- Initial site of application: inner surface of the right deltoid area
- Second application after 48 hours: the next patch was applied to the inner surface of the left deltoid area.
- Third application: made to the original site of the first application - to the inner surface of the right deltoid area.
- Fourth application: made to the site of the second application - on the medial surface of the left deltoid area.
- The cycle of rotation of the sites of application was alternately between the inner surfaces of the right and left deltoid area for a total of 10 sensitisation applications.
- The concluding challenge tests were applied simultaneously as precise duplicates to the inner surface of each deltoid area.
- The cycle of rotation of sites was continued throughout the series of 10 identical sensitisation applications of the eight preparations: April 13th, 14th, 16th, 19th, 21st, 23rd, 26th, 28th and 30th and May 3rd and 5th 1971
- The final visit on May 5th was for the removal of patches applied on May 3rd.
- The first patches applied on April 13th and removed April 14th correspond to the 24 -hour period of contact correspond to the initial 24 -hour test to check for primary signs of irritation.

CHALLENGE
- There was a rest period after the application of the last sensitisation test, where the development of senstisation was allowed to develop.
- The challenge test series was applied on May 18th 1971, in an identical manner as previously described, except that the tests were applied in duplicate, with one set of eight patches being applied to the inner surface of each deltoid area.
- The challenges were removed on ,May 20th 1971 and a 48 -hour reading was recorded.
- The patches were not re-applied, but a loosely applied cover of plain sterile gauze was made to protect the test site area from washing, scratching or other interference with the development of any delayed reactions.
- A 72 -hour reading was taken on May 21st 1971 in order to complete the study.
- Observations were also made on May 24th to detect the development of any retarded responses, when the subjects returned to receive their stipends for participating in the study.

PRECAUTIONARY MEASURES
- In addition to these test studies, there were routine precautionary measures performed on April 12th 1971 on the primary irritative potentialites of the materials by applying them in the same manner as previously described on a pilot group of 10 subjects, prior to the tests conducted on the main 58 volunteers.
- On April 12th 1971, eight preparations were applied in closed patches to the inner surface on the left deltoid area.
- The 10 subjects of the pilot group become part of the full complement of the 58 subjects, so that at the end of the sensitisation series, the 10 individuals received 11 sensitising applications compared to the rest, who had been subjected to only 1 sensitising applications.

Challenge controls:

No controls

Positive control substance(s):

no

Results and discussion

Positive control results:

No positive control tested

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.5 mL

No. with + reactions:

0

Total no. in group:

53

Clinical observations:

No reactions observed

Remarks on result:

no indication of skin sensitisation

Results 2

Reading:

2nd reading

Hours after challenge:

144

Group:

test chemical

Dose level:

0.5 mL

No. with + reactions:

0

Total no. in group:

53

Clinical observations:

No reactions observed

Remarks on result:

no indication of skin sensitisation

Results 3

Reading:

other: no readings

Group:

positive control

Total no. in group:

0

Remarks on result:

not measured/tested

Results 4

Reading:

other: no readings

Group:

negative control

Total no. in group:

0

Remarks on result:

not measured/tested

Any other information on results incl. tables

- 19 tape reactions observed. Seven subjects developed one reaction each, four showed 2 such reactions and one person showed 4 reactions. Reactions consisted of redness and papular types with only two of the responses being slightly vesicular (in the subject with the 4 reactions).

- Primary irritative properties of the test substance were studied with 10 volunteers before actual testing (pilot group). After 24 -hours, there were no complaints of itching, burning or other paresthesias; patch test sites showed no reactions.

Applicant's summary and conclusion

Conclusions:

Under the conditions of the Draize test, no primary irritation or sensitising effects occurred following application of the test substance on human
subjects.

Executive summary:

This study was conducted in order to assess the irritative and sensitisaing potentials of the eight formulations of the test substance 2-tert-butyl-1,4-dimethoxybenzene.

Fifty-three volunteers (39 females and 14 males) of representative age groups (17 -64 years) were randomly chosen and took part in a full sensitisation and challenge test study in accordance with the Draize repeated insult technique. There were routine precautionary measures performed prior to the main test for the primary irritative potentialites of the materials by applying them in the same manner as previously described on a pilot group of 10 subjects, prior to the tests conducted on the main 58 volunteers. There were no reactions in response to the patch tests containing any of the eight preparations, either in the sensitisation or challenge test series. The only reactions that were observed were due to the adhesive tape, where there were a total of 19 reactions in twelve of the subjects. Therefore, this suggests that there was a potential for a reaction had the formulations been adequately stimulating in the 53 subjects who completed the fully study.

Therefore, it can be concluded that none of the eight preparations of the test substance 2-tert-butyl-1,4-dimethoxybenzene in this study showed primary irritation or sensitising effects on the 53 human subjects tested.