2-ethylhexyl 4-(dimethylamino)benzoate

Endpoint summary

Description of key information

2-ethylhexyl 4-(dimethylamino)benzoate is not considered to be a skin sensitizer.

In two repeated insult patch tests carried out in human volunteers, the test material was not capable of eliciting visible skin changes consistent with the criteria deemed characteristic of a primary irritant, fatiguing agent or sensitiser at concentrations of 4 and 1.5 % in U.S.P. white petrolatum.

Moreover, 2-ethylhexyl 4-(dimethylamino)benzoate showed no skin sensitisation in guinea pigs study.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline available

Principles of method if other than guideline:

A repeated insult patch test was carried out on 50 human volunteers to determine if the test material is capable of irritating the skin of humans under controlled test conditions and if so, to classify the test material as a primary irritant, fatiguing agent and/or sensitiser on the basis of the visible clinical responses.

GLP compliance:

no

Remarks:

The study pre-dates the inception of GLP

Type of study:

patch test

Justification for non-LLNA method:

Study conducted using human volunteers prior to the adoption of the LLNA guideline.

Species:

other: human

Strain:

other: Not applicable

Sex:

not specified

Details on test animals and environmental conditions:

TEST SUBJECTS
- Source: Volunteers from a local population

QUALIFYING CRITERIA
- General well-being
- Absence of any skin disease which might be confused with skin reactions from the test material
- Willingness to cooperate
- Dependability and intelligence in following directions
- Reading, understanding and signing an informed-consent contract (in the case of minors, parental consent was obtained)

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

Test material applied as received (4.0 % in U.S.P. white petroleum)

Day(s)/duration:

24 hours of contact followed by 24 hours of rest (Monday to Friday) then 48 hours of rest over the weekend for fifteen applications

Adequacy of induction:

not specified

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

Test material applied as received (4.0 % in U.S.P. white petroleum)

Day(s)/duration:

24 hours

Adequacy of challenge:

not specified

No. of animals per dose:

50 human volunteers were exposed

Details on study design:

A. INDUCTION EXPOSURE
- No. of exposures: 15
- Exposure period: A lintine pad was moistened with the test material as supplied. The treated pad was placed on its predesignated site, covered and sealed with overlapping strips of Blenderm tape. This cover was kept intact for twenty-four hours. At the end of twenty-four hours, the seal was broken and the patch removed.
- Test groups: Test material as received (4 % in U.S.P. white petrolatum)
- Control group: No
- Site: The upper arm
- Frequency of applications: After the patch was removed, the contact sites were rested for twenty-four hours. They were then re-examined to determine if any changes had occurred since the previous examination. If the contact sites manifested no changes, the test material was re-applied to the same site. If significant irritation (2+ or more) was observed, the investigator, at his discretion, had the option either of resting the individual or of applying the test material to a new site for the next contact period. This cycle was repeated in this manner on Mondays, Wednesdays and Fridays. On weekends, a forty-eight-hour rest period was permitted between removal and re-application of the test material.
- Scoring: The skin sites were examined after patch removal and gross changes, if present, were graded on a scale of 1 to 4. Absence of any visible changes was assigned a 0 value.
Scoring Criteria:
0 = No reactions
1+ = Slight erythema
2+ = Marked erythema
3+ = Marked erythema, oedema, with or without a few vesicles
4+ = Marked erythema, oedema, with vesicles and oozing

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: After the fifteenth induction application, the participants were rested for two weeks before being challenged. The sites of contact used previously were challenged.
- Exposure period: Twenty-four hours under occlusion.
- Test groups: Test material as received (4 % in U.S.P. white petrolatum)
- Control group: No
- Site: The upper arm
- Evaluation (hr after challenge): After patch removal, the contact site was examined immediately and following at intervals of twenty-four and forty-eight hours.
- Scoring: The skin sites were examined after patch removal and gross changes, if present, were graded on a scale of 1 to 4. Absence of any visible changes was assigned a 0 value.

Positive control substance(s):

no

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

Test material applied as received (4.0 % in U.S.P. white petroleum)

No. with + reactions:

0

Total no. in group:

50

Clinical observations:

No observations

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

Test material applied as received (4.0 % in U.S.P. white petroleum)

No. with + reactions:

0

Total no. in group:

50

Clinical observations:

No observations

Remarks on result:

no indication of skin sensitisation

Interpretation of results:

GHS criteria not met

Remarks:

not skin sensitizer (4%)

Conclusions:

Under the conditions of this study, the test material was determined not to be a skin sensitiser.

Executive summary:

The skin sensitisation potential of the test material was investigated in human volunteers using a repeated insult patch test.

The patch test was performed on a group of 50 individuals from a local population who volunteered to participate in the study. Individuals selected for the study met the following criteria: General well-being, absence of any skin disease which might be confused with skin reactions from the test material, willingness to cooperate, dependability and intelligence in following directions and reading, understanding and signing an informed-consent contract.

A lintine pad was moistened with the test material as supplied (at a 4.0 % concentration in U.S.P. white petrolatum). The treated pad was placed on its predesignated site on the upper arm, covered, and sealed with overlapping strips of tape. This cover was kept intact for twenty-four hours. At the end of twenty-four hours, the seal was broken and the patch removed. The skin sites were examined and gross changes and if they were present, were graded on a scale of 1 to 4. Absence of any visible changes was assigned a 0 value. After the patch was removed, the contact sites were rested for twenty-four hours. They were then re-examined to determine if any changes had occurred since the previous examination. If the contact sites manifested no changes, the test material was reapplied to the same site. If significant irritation was observed, the investigator, at his discretion, had the option either of resting the individual or of applying the test material to a new site for the next contact period. This cycle was repeated in this manner on Mondays, Wednesdays and Fridays. On weekends, a forty-eight-hour rest period was permitted between removal and re-application of the test material.

After the fifteenth application, the participants were rested for two weeks before being challenged. The sites of contact used previously were challenged with the test material for twenty-four hours under occlusion. After removal, the contact site was examined immediately and following at intervals of twenty-four and forty-eight hours. Observations were recorded on a daily basis during treatment.

No visible skin changes signifying reaction to injury were observed in any of the 50 subjects following any of the test material applications, including the challenge.

Under the conditions of this study, the test material was not capable of eliciting visible skin changes consistent with the criteria deemed characteristic of a primary irritant, fatiguing agent or sensitiser.

Reference 2

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

25 July 1972 to 31 August 1972

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

no negative or positive controls

GLP compliance:

no

Remarks:

The study pre-dates the inception of GLP

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The study was conducted prior to the LLNA becoming the preferred test method in the EU.

Species:

guinea pig

Strain:

other: White

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 300 to 500 grams
- Housing: Individually housed
- Diet: Commercial rabbit pellets, greens and carrots
- Water: Yes

Route:

intradermal

Vehicle:

physiological saline

Remarks:

pyrogen free

Concentration / amount:

0.05 mL of 0.1 % solution for the first injection, followed by nine injections of 0.1 mL of 0.1 % solution

Day(s)/duration:

Injections were performed three times weekly, until ten had been made.

Adequacy of induction:

not specified

No.:

#1

Route:

intradermal

Vehicle:

physiological saline

Remarks:

pyrogen free

Concentration / amount:

0.05 mL of 0.1 % solution

Day(s)/duration:

Two weeks after the tenth induction injection

Adequacy of challenge:

not specified

No. of animals per dose:

10 males

Details on study design:

A. INDUCTION EXPOSURE
- No. of exposures: 10
- Exposure period: Approximately 24 days
- Test groups: 1 test group
- Control group: Yes, distilled water. The same amount was injected intra-cutaneously as the test material.
- Site: The hair was removed from the backs of the guinea pigs with an electric clipper prior to initiation of study and whenever necessary throughout the study. The ten sensitising injections were performed at random in the shaved back areas.
- Frequency of applications: The injections were performed three times weekly, until a total of ten had been made.
- Concentrations: A 0.1 % solution of the suspension of test material in sterile pyrogen free physiological saline was injected intra-cutaneously, using sterile 26 gauge hypodermic needles and sterile tuberculin syringes.
- Other: Twenty-four hours after each injection scorings were recorded for the diameter, height and redness of the reactions (if any).

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Two weeks after the tenth induction injection, a challenge (re-test) injection was performed
- Exposure period: 1 day
- Test groups: 1 test group
- Control group: Yes, distilled water. The same amount was injected intra-cutaneously as the test material.
- Site: The hair was removed from the backs of the guinea pigs with an electric clipper prior to initiation of study and whenever necessary throughout the study. The eleventh (re-test) injection was made just below the region of the ten sensitising injections.
- Concentrations: A 0.1 % solution of the suspension of test material in sterile pyrogen free physiological saline
- Evaluation (hr after challenge): Twenty-four hours after each injection scorings were recorded for the diameter, height and redness of the reactions (if any). A comparison of the reaction following the challenge (re-test) injection was made with the average score for the ten sensitising injections.
When the value for the challenge (re-test) score is substantially higher than the average of the ten original scores, the test material may be considered to have produced sensitisation in the male albino guinea pig. The degree of sensitisation is proportional to the increase in the final score, compared to the average of the ten sensitising scores.

Challenge controls:

no

Positive control substance(s):

no

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.1 %

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

None noted

Remarks on result:

no indication of skin sensitisation

Interpretation of results:

GHS criteria not met

Remarks:

Not skin sensitizer

Conclusions:

Under the conditions of this study, the test material is not considered to be a skin sensitiser.

Executive summary:

A study was conducted to investigate the skin sensitisation potential of the test material using methodology equivalent to the standardised guideline OECD 406.

Ten white male guinea pigs were used; the hair was removed from their backs with an electric clipper prior to initiation of study and whenever necessary throughout the study. A 0.1 % solution of the suspension of test material in sterile pyrogen free physiological saline was injected intra-cutaneously. The injections were performed three times weekly, until a total of ten had been made (0.05 mL for the first, 0.1 mL for the remaining nine injections). These ten sensitising injections were performed at random in the shaved back areas. The eleventh (re-test) injection was made just below the region of the ten sensitising injections (0.05 mL). Distilled water was used as a control in the study; the same amount was injected intra-cutaneously as the test material.

Twenty-four hours after each injection scorings were recorded for the diameter, height and redness of the reactions (if any). A comparison of the reaction following the challenge (re-test) injection was made with the average score for the ten sensitising injections. When the value for the challenge (re-test) score is substantially higher than the average of the ten original scores, the test material may be considered to have produced sensitisation in the male albino guinea pig. The degree of sensitisation is proportional to the increase in the final score, compared to the average of the ten sensitising scores.

Nine animals showed no reaction to the test material throughout the induction and challenge phases. One guinea pig was awarded a score of 1.0 for both the average of ten sensitising injections and the score for challenge. However, the degree of sensitisation was judged to be zero.

When the test material was injected intra-cutaneously it produced sensitisation scores identical to that of the distilled water control. On the challenge (re-test) injection none of the animals exhibited reactions higher than the average of the original scores.

Under the conditions of this study, the test material is not considered to be a skin sensitiser.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Three studies are available to address this endpoint, two studies in human (patch test) and one study in guinea pigs. All were awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).

 

Shelanski (1974) - Human

The two studies were conducted in human volunteers (both by Shelanski, 1974) using a repeated insult patch test. Both studies followed the same methodology using the test material as supplied. For one study, the test material was received as a 4 % concentration in U.S.P. white petrolatum; for the second study, the test material was received as a 1.5 % concentration in U.S.P. white petrolatum.

Each patch test was performed on a group of 50 individuals from a local population who volunteered to participate in the study. Individuals selected for the study met the following criteria: General well-being, absence of any skin disease which might be confused with skin reactions from the test material, willingness to cooperate, dependability and intelligence in following directions and reading, understanding and signing an informed-consent contract.

A lintine pad was moistened with the test material as supplied. The treated pad was placed on its predesignated site on the upper arm, covered, and sealed with overlapping strips of tape. This cover was kept intact for twenty-four hours. At the end of twenty-four hours, the seal was broken and the patch removed. The skin sites were examined and gross changes and if they were present, were graded on a scale of 1 to 4. Absence of any visible changes was assigned a 0 value. After the patch was removed, the contact sites were rested for twenty-four hours. They were then re-examined to determine if any changes had occurred since the previous examination. If the contact sites manifested no changes, the test material was reapplied to the same site. If significant irritation was observed, the investigator, at his discretion, had the option either of resting the individual or of applying the test material to a new site for the next contact period. This cycle was repeated in this manner on Mondays, Wednesdays and Fridays. On weekends, a forty-eight-hour rest period was permitted between removal and re-application of the test material.

After the fifteenth application, the participants were rested for two weeks before being challenged. The sites of contact used previously were challenged with the test material for twenty-four hours under occlusion. After removal, the contact site was examined immediately and following at intervals of twenty-four and forty-eight hours. Observations were recorded on a daily basis during treatment.

No visible skin changes signifying reaction to injury were observed in any of the 50 subjects in either test following any of the test material applications, including the challenge.

Under the conditions of these studies, the test material was not capable of eliciting visible skin changes consistent with the criteria deemed characteristic of a primary irritant, fatiguing agent or sensitiser at concentrations of 4 and 1.5 % in U.S.P. white petrolatum.

 

Green (1972) - Guinea pig

The study was conducted to investigate the skin sensitisation potential of the test material using methodology equivalent to the standardised guideline OECD 406.

Ten white male guinea pigs were used; the hair was removed from their backs with an electric clipper prior to initiation of study and whenever necessary throughout the study. A 0.1 % solution of the suspension of test material in sterile pyrogen free physiological saline was injected intra-cutaneously. The injections were performed three times weekly, until a total of ten had been made (0.05 mL for the first, 0.1 mL for the remaining nine injections). These ten sensitising injections were performed at random in the shaved back areas. The eleventh (re-test) injection was made just below the region of the ten sensitising injections (0.05 mL). Distilled water was used as a control in the study; the same amount was injected intra-cutaneously as the test material.

Twenty-four hours after each injection scorings were recorded for the diameter, height and redness of the reactions (if any). A comparison of the reaction following the challenge (re-test) injection was made with the average score for the ten sensitising injections. When the value for the challenge (re-test) score is substantially higher than the average of the ten original scores, the test material may be considered to have produced sensitisation in the male albino guinea pig. The degree of sensitisation is proportional to the increase in the final score, compared to the average of the ten sensitising scores.

Nine animals showed no reaction to the test material throughout the induction and challenge phases. One guinea pig was awarded a score of 1.0 for both the average of ten sensitising injections and the score for challenge. However, the degree of sensitisation was judged to be zero.

When the test material was injected intra-cutaneously it produced sensitisation scores identical to that of the distilled water control. On the challenge (re-test) injection none of the animals exhibited reactions higher than the average of the original scores.

Under the conditions of this study, the test material is not considered to be a skin sensitiser.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available data, no classification for skin sensitisation is required for 2-ethylhexyl 4-(dimethylamino)benzoate according to the Regulation (EC) No 1272/2008.