2-(6-methoxybenzofuran-2-yl)-1,3-dimethyl-5-(methylsulphonyl)1H-benzimidazolium acetate

Endpoint summary

Description of key information

The substance was found to be devoid of skin-sensitizing (contact allergenic) potential in albino guinea-pigs.

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Principles of method if other than guideline:

Optimization test*, an intracutaneous sensitization procedure similar to the method recommended in the "Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics" (1959), the US Association of Food and Drug Officials (AFDO).

*Maurer, Th., Thomann, P., Weirich, E.G. and Hess, R., (1975). The Optimization test in the guinea pig. A method for the predictive evaluation of the contact allergenicity of Chemicals. Agents and Actions Vol. 5 (2), 174-179, 1975

GLP compliance:

no

Type of study:

Maurer optimisation test

Justification for non-LLNA method:

Old test

Species:

guinea pig

Strain:

Pirbright-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Weight at study initiation: between 350 to 400 grams.
- Housing: animals were housed individually in Macrolon cages, type 3.
- Diet: standard guinea pig pellets - NAFAG No. 830, Gossau SG - and fresh carrots, ad libitum.
- Water: ad libitum.

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 1 °C
- Relative humidity: 55 ± 5 %
- Photoperiod: 14 hours light cycle day.

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

0.1 %

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

0.1 %

Route:

epicutaneous, occlusive

Vehicle:

other: vas. alb.

Concentration / amount:

1 %

Day(s)/duration:

24 hours

No. of animals per dose:

10 males and 10 females

Details on study design:

During the induction period the animals received one injection every second day (except weekends) to a total of 10 intracutaneous injections of a freshly prepared 0.1 % solution of test item in physiological saline.
One control group was treated with the vehicle alone ("negative control").
On the first day, injections of 0.1 ml were administered into the shaven skin of the right flank and the back, while on the following days a single intracutaneous injection was given into the back.

During the second and third week of the induction period the test compounds were incorporated in a mixture, of the normal vehicle with complete Bacto Adjuvant (vehicle : adjuvant = 1 : 1).

Fourteen days after the last sensitizing injection, a challenge injection of 0.1 ml of a freshly prepared 0. 1 % solution of test item was administered into the skin of the left flank.

Twenty-four hours after each injection during the first week of the induction period and 24 hours after the challenge injection the reactions were recorded.
Before examination, the reaction sites were depilated chemically (Veet, 5 minutes). The two largest perpendicular diameters (in mm) and the increase in the skin- fold thickness (in mm) were measured, and by multiplication of these values a "reaction volume" was obtained (in µl) for each reading from each animal. The mean volume plus one standard deviation of the induction reactions observed in the individual animal in the first week was taken as representing the skin irritation "threshold" for each animal. Any challenge reaction greater than this threshold value in the induction period was graded as an allergic reaction and the animal termed "positive". The number of "positive" animals in the test group was compared with the number of animals in the control group (treated with the vehicle alone) that showed a non-specific reaction of at least the same magnitude ("negative control").

Ten days after the intracutaneous challenge injection, a subirritant dose of the test compound was applied epicutaneously under occlusive dressings which were left in place for 24 hours.

Positive control substance(s):

no

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.1% - intradermal challenge

No. with + reactions:

2

Total no. in group:

20

Remarks on result:

no indication of skin sensitisation

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

1 % - epicutaneous challenge

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

no indication of skin sensitisation

Reading:

1st reading

Group:

negative control

Dose level:

both intradermal and epicutaneous challenge

No. with + reactions:

2

Total no. in group:

20

Remarks on result:

no indication of skin sensitisation

Group:

positive control

Remarks on result:

not measured/tested

No differences between the test group and the vehicle-treated controls were seen, after either intradermal or epidermal challenge application of test item.

Interpretation of results:

other: not classified, according to the CLP Regulation (EC) No 1272/2008

Conclusions:

Not skin sensitising

Executive summary:

The skin sensitisation potential of test item was investigated in an optimation test proposed by Maurer et al (1973), an intracutaneous sensitization procedure similar to the method recommended in the "Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics" (1959), the US Association of Food and Drug Officials (AFDO). The test was performed on groups of 10 male and 10 female guinea pigs. During the induction period the animals received one injection every second day (except weekends) to a total of 10 intracutaneous injections of a freshly prepared 0.1 % solution of test item in physiological saline. One control group was treated with the vehicle alone.

On the first day, injections of 0.1 ml were administered into the shaven skin of the right flank and the back, while on the following days a single intracutaneous injection was given into the back. During the second and third week of the induction period the test compounds were incorporated in a mixture, of the normal vehicle with complete Bacto Adjuvant (vehicle : adjuvant = 1 : 1). Fourteen days after the last sensitizing injection, a challenge injection of 0.1 ml of a freshly prepared 0.1 % solution of test item was administered into the skin of the left flank. Twenty-four hours after each injection during the first week of the induction period and 24 hours after the challenge injection the reactions were recorded. Before examination, the reaction sites were depilated chemically. The two largest perpendicular diameters (in mm) and the increase in the skin- fold thickness (in mm) were measured, and by multiplication of these values a "reaction volume" was obtained (in µl) for each reading from each animal. The mean volume plus one standard deviation of the induction reactions observed in the individual animal in the first week was taken as representing the skin irritation "threshold" for each animal. Any challenge reaction greater than this threshold value in the induction period was graded as an allergic reaction and the animal termed "positive". The number of "positive" animals in the test group was compared with the number of animals in the control group (treated with the vehicle alone) that showed a non-specific reaction of at least the same magnitude ("negative control"). Ten days after the intracutaneous challenge injection, a subirritant dose of the test compound was applied epicutaneously under occlusive dressings which were left in place for 24 hours. Two out of 20 animals were found to have a positive reaction after the intracutaneous challenge injection, while no positive reactions were recorded after the epicutaneous challenge application. Hence, based on the above information, it was concluded that substance was devoid of skin-sensitizing (contact allergenic) potential in albino guinea-pigs.

Conclusion

A response lower than 30 % was recorded, thus the substance does not meet the criteria to be classified as skin sensitizer, according to the CLP Regulation (EC) No 1272/2008.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The skin sensitisation potential of test item was investigated in an optimation test proposed by Maurer et al (1973), an intracutaneous sensitization procedure similar to the method recommended in the "Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics" (1959), the US Association of Food and Drug Officials (AFDO). The test was performed on groups of 10 male and 10 female guinea pigs. During the induction period the animals received one injection every second day (except weekends) to a total of 10 intracutaneous injections of a freshly prepared 0.1 % solution of test item in physiological saline. One control group was treated with the vehicle alone.

On the first day, injections of 0.1 ml were administered into the shaven skin of the right flank and the back, while on the following days a single intracutaneous injection was given into the back. During the second and third week of the induction period the test compounds were incorporated in a mixture, of the normal vehicle with complete Bacto Adjuvant (vehicle : adjuvant = 1 : 1). Fourteen days after the last sensitizing injection, a challenge injection of 0.1 ml of a freshly prepared 0.1 % solution of test item was administered into the skin of the left flank. Twenty-four hours after each injection during the first week of the induction period and 24 hours after the challenge injection the reactions were recorded. Before examination, the reaction sites were depilated chemically. The two largest perpendicular diameters (in mm) and the increase in the skin- fold thickness (in mm) were measured, and by multiplication of these values a "reaction volume" was obtained (in µl) for each reading from each animal. The mean volume plus one standard deviation of the induction reactions observed in the individual animal in the first week was taken as representing the skin irritation "threshold" for each animal. Any challenge reaction greater than this threshold value in the induction period was graded as an allergic reaction and the animal termed "positive". The number of "positive" animals in the test group was compared with the number of animals in the control group (treated with the vehicle alone) that showed a non-specific reaction of at least the same magnitude ("negative control"). Ten days after the intracutaneous challenge injection, a subirritant dose of the test compound was applied epicutaneously under occlusive dressings which were left in place for 24 hours. Two out of 20 animals were found to have a positive reaction after the intracutaneous challenge injection, while no positive reactions were recorded after the epicutaneous challenge application. Hence, based on the above information, it was concluded that substance was devoid of skin-sensitizing (contact allergenic) potential in albino guinea-pigs.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

According to the CLP Regulation (EC) No 1272/2008, 3.4 Respiratory or skin sensitisation section, skin sensitizer means a substance that will lead to an allergic response following skin contact.

When an adjuvant type test method for skin sensitisation is used, a response of at least 30 % of the animals is considered as positive.

A response lower than 30 % was obtained in Maurer optimization test.

In conclusion, Fluorescent Brightener 363 does not meet the criteria to be classified as skin sensitizer, according to the CLP Regulation (EC) No 1272/2008.