N-(2-ethylhexyl)-8,9,10-trinorborn-5-ene-2,3-dicarboximide

Endpoint summary

Description of key information

An OECD 406 skin sensitisation (Buehler type) study was performed in guinea pigs to determine the skin sensitisation properties of MGK 264. The route of induction and challenge application was by topical application. For the induction phase MGK 264 was applied without vehicle (100%) and mild irritation was recorded. For the challenge application a 55% solution of MGK 264 in the vehicle (PEG 400) was used. After the challenge test 19/20 test animals had skin reactions of 1 or 2 whilst the challenge control animals had skin reactions of 0 to ± . Therefore based on the experimental study and according to EC 1272/2008 the test substance would be categorised as a category 1B for skin sensitisation ( >=15% responding at >=20% topical induction dose).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 November 2004 to 04 April 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

July 17, 1992; Buehler Test

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

March 2003

Deviations:

not specified

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

Study to satisfy EPA requirements valid at the time of study conduct.
Study performed prior to the recommendation to use LLNA method.
Valid, reliable data was obtained from this test so there is no justification for any further testing involving vertebrates.

Specific details on test material used for the study:

MGK® 264
Lot No.: AA 7093
Purity: 95.2% MGK 264 (From CofA)

Species:

guinea pig

Strain:

Hartley

Remarks:

Hartley-derived albino guinea pigs

Sex:

male/female

Details on test animals and environmental conditions:

The animal room temperature and relative humidity ranges were 62-72°F (17-22°C) and 36-58%, respectively. Environmental control equipment was monitored and adjusted as necessary to minimize fluctuations in the animal room environment. Light timers were set to maintain a 12-hour lightll2-hour dark cycle and room ventilation was set to produce 10-15 air changeslhour. The room temperature and relative humidity were recorded a minimum of once daily.

Route:

other: Chamber Application

Vehicle:

unchanged (no vehicle)

Concentration / amount:

100%

Day(s)/duration:

3 induction cycles (day 0, 6 and 13) with 24 and 48 hour observations.

Adequacy of induction:

highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically

No.:

#1

Route:

other: Chamber Application

Vehicle:

polyethylene glycol

Remarks:

PEG 400

Concentration / amount:

55%

Day(s)/duration:

2 days (48 Hours)

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

4: 2 Male/ 2 Female inInitial range finding study
4: 2 Male/ 2 Female inInitial range finding study (challenge)
20: 10 Male/ 10 Female in main experiment
10: 5 Male/ 5 Female Challenge Contol Animals

Details on study design:

Initial Range finding study:
4: 2 Male/ 2 Female inInitial range finding study
4: 2 Male/ 2 Female inInitial range finding study (challenge)
On the day prior to dose administration for each range-finding study, four topical range-finding guinea pigs were weighed and the hair removed from the right and left side of the animals with a small animal clipper. Care was taken to avoid abrading the skin during clipping procedures.
On the following day for each range-finding study, four concentrations of the test article were prepared and each concentration was applied to the clipped area of each topical range-finding animals (0.3mL) and seured under 25mm Hilltop Chamber occlusive patch.
The test article was utilized at 100% and at 75%, 65%, 60%, 55%, 50% and 25% w/w in PEG 400 for the initial range-finding study.

This study consisted of two topical range-finding groups, a test group, a challenge control group and rechallenge control group. A rechallenge group was maintained on this study but was not utilized since the challenge results were definitive.
On the day prior to each dose administration, the guinea pigs had the hair removed with a small animal clipper. Care was taken to avoid abrading the skin.
Introduction:
20: 10 Male/ 10 Female in main experiment
On the day prior to the first induction dose administration (day -I), all test and control animals were weighed and the hair was removed from the left side of the test animals. On the day following clipping (day 0), chambers were applied at 100% concentration to all 20 in the test group.
The induction procedure was repeated on study day 6 and on study day 13 so that a total of three consecutive induction exposures were made to the test animals.

Following a 2-week rest period, a challenge was performed whereby the 20 test and 10 previously untreated (naive) challenge controls were topically treated with 55% MGK 264. Challenge response of the test animals were compared to the challenge control animals.

The sensitization potential of the test article was based on the dermal responses observed on the test and control animals at challenge. Generally, dermal scores of >= 1 in the test animals with scores of 0 to ± (slightly patchy erythma) noted in the controls are considered indicative of sensitization. Dermal scores of 1 in both the test and control animals are generally considered equivocal unless a higher dermal response (>= grade 2) is noted in the test animals. Group mean dennal scores were calculated for challenge. A response of at least 15 percent in a nonadjuvant test should be expected for a mild to moderate sensitizer.

Challenge controls:

Challenge :
5 Male/ 5 Female Challenge Contol Animals
On the day prior to challenge dose administration, the test and challenge control animals were weighed and the hair was removed from the right side of the animals. On the day following clipping (day 27), the animals received a topical application of 55% concentration in PEG 400.

Following chamber application, the trunk of the animal was wrapped with elastic wrap which was secured with adhesive tape to prevent removal of the chamber and the animal was returned to its cage.
Approximately six hours after chamber application, the binding materials were removed. The test sites were wiped with gauze moistened in deionized water, followed by dry gauze, to remove test article residue. The animals were then returned to their cages.

Positive control substance(s):

yes

Remarks:

1-Chloro-2,4-dinitrobenzene (DNCB)

Positive control results:

Using 1-Chloro-2,4-dinitrobenzene (DNCB) as a positive control, CRL-Ohio Division, Spencerville, Ohio, has completed a study during the past six months which provided historical control data for contact sensitization to this agent utilizing the test system described herein (Modified Buehler Design). Following induction at 0.1% w/v DNCB in acetone/ethanol, challenge at levels of 0.1 % and 0.05% w/v DNCB in acetone/ethanol, and rechallenge at levels of 0.05% and 0.08% w/v DNCB in acetone/ethanol, contact sensitization response was observed, thereby demonstrating the susceptibility of the test system to this sensitizing agent.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

55%

No. with + reactions:

19

Total no. in group:

20

Clinical observations:

6/20 test animals had dermal scores of 2 and 13/20 had dermal scores of 1 at the 24 hr scoring interval

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

55%

No. with + reactions:

13

Total no. in group:

20

Clinical observations:

13/20 with a dermal score of 1 at the 24 hr scoring

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

55%

No. with + reactions:

6

Total no. in group:

10

Clinical observations:

4/10 animals graded as 0; 6/10 graded ± (slightly patchy erythema)

Remarks on result:

other: Naive control animals

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

55%

No. with + reactions:

3

Total no. in group:

10

Clinical observations:

7/10 graded as 0; 3/10 graded ± (slightly patchy erythema)

Remarks on result:

other: naive control animals

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

0.05%

No. with + reactions:

7

Total no. in group:

20

Clinical observations:

dermal scores of 1 were noted in 7/20 test animals

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

rechallenge

Hours after challenge:

24

Group:

positive control

Dose level:

0.05%

No. with + reactions:

7

Total no. in group:

20

Clinical observations:

dermal scores of 1 were noted in 7/20 test animals

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

0.1%

No. with + reactions:

20

Total no. in group:

20

Clinical observations:

dermal scores of 1 to 2 were noted in 20/20 test animals

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

rechallenge

Hours after challenge:

24

Group:

positive control

Dose level:

0.08%

No. with + reactions:

13

Total no. in group:

20

Clinical observations:

dermal scores of 1 were noted in 13/20 test animals

Remarks on result:

positive indication of skin sensitisation

Topical Range-Finding Studies

The results of the initial range-finding study indicated that a test article concentration of 100% was considered appropriate for induction since it was the highest concentration that was mildly irritating. A second range-finding study was conducted to determine the appropriate concentration for challenge. The results of the second range-finding study indicated that a test article concentration of 55% was considered appropriate for challenge since it was the highest concentration that was essentially nonirritating.

Sensitization Study

Following challenge with 55% MGK 264, dermal scores of 2 were noted in 6/20 test animals at the 24-hour scoring interval. Dermal scores of 1 were noted in 13/20 test animals at the 24-hour scoring interval. At the 48 -hour scoring interval, dermal scores of 1 were noted in 13/20 test animals. Dermal reactions in the remaining test animals and all of the challenge control animals were limited to scores of 0 to ± (slightly patchy erythema). Group mean dermal scores were noted to be higher in the test animals as compared with the challenge control animals.

BodyWeights

The sensitization study animals gained weight during the test period and generally appeared in good health.

Historical Control Data

Using l-Chloro-2,4-dinitrobenzene (DNCB) as a positive control, CRL-Ohio Division, Spencerville, Ohio, has completed a study during the past six months which provided historical control data for contact sensitization to this agent utilizing the test system described herein (Modified Buehler Design). Following induction at 0.1% w/v DNCB in acetone/ethanol, challenge at levels of 0.1 % and 0.05% w/v DNCB in acetone/ethanol, and rechallenge at levels of 0.05% and 0.08% w/v DNCB in acetone/ethanol, contact sensitization response was observed, thereby demonstrating the susceptibility of the test system to this sensitizing agent.

 

CONCLUSION

Based on the results of this study, MGK® 264 is considered to be a contact sensitizer in guinea pigs. The results of the DNCB historical control study demonstrated that a valid test was performed and indicated that the test design would detect potential contact sensitizers. According to the EPA-OPPTS Toxicity Categories, the test article would be considered to be a sensitizer or is positive for sensitization.

Interpretation of results:

other: According to EC 1272/2008 the test substance would be categorised as a category 1B for sensitisation (>=15% responding at >=20% topical induction dose)

Conclusions:

Based on the results of this study, MGK® 264 is considered to be a contact sensitizer in guinea pigs. The results of the DNCB historical control study demonstrated that a valid test was performed and indicated that the test design would detect potential contact sensitizers. According to the EPA-OPPTS Toxicity Categories, the test article would be considered to be a sensitizer or is positive for sensitization.

According to EC 1272/2008 the test substance would be categorised as a category 1B for sensitisation (>=15% responding at >=20% topical induction dose).

Executive summary:

Based on the results of this study, MGK® 264 is considered to be a contact sensitizer in guinea pigs. The results of the DNCB historical control study demonstrated that a valid test was performed and indicated that the test design would detect potential contact sensitizers. According to the EPA-OPPTS Toxicity Categories, the test article would be considered to be a sensitizer or is positive for sensitization.

According to EC 1272/2008 the test substance would be categorised as a category 1B for sensitisation (>=15% responding at >=20% topical induction dose).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

According to EC 1272/2008 the test substance would be categorised as a category 1B for sensitisation (>=15% responding at >=20% topical induction dose).

Respiratory sensitisation

Endpoint conclusion

Additional information:

No data available.