N-(4-aminophenyl)aniline

Endpoint summary

Description of key information

4-ADPA was not irritating to skin in a guideline study (TG 404) (Bayer AG 1982a). In another guideline study (Monsanto Co. 1984c) the test substance showed slightly to moderate irritating effects on the skin of rabbits, which were reversible within 7 days. Transient moderate irritant effects were observed after instillation of 4-ADPA into the eyes of rabbits (Bayer AG 1982b, Monsanto Co. 1984d). The conjunctival redness mean scores of 4/6 animals were >2  (Monsanto Co. 1984), indicating an eye irrtating potential of 4-ADPA according to the GHS classification criteria, but this observation was not confirmed by the result of another guideline conform study. The reason for the discrepancy between the results of the two available studies is not known. 

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Skin

Non-human information

In an OECD Guideline study (TG 404) 500 mg of 4-ADPA (moistened with water) was applied under semi-occlusive conditions to the clipped intact skin of 3 rabbits for 4 hours. There were no signs of irritation at 1, 24, 48, 72 hours and 7 days. The skin response scored according to the method of Draize was all time points 0 (Bayer AG 1982a).

A further guideline study with application of finely ground 4-ADPA to two sites of six rabbits under identical test conditions stated a practically non-irritating effect after 4 hour exposure (slight erythema: 0.5 mean 24, 48, 72 h, without edema, reversible within 7 days). Whereas prolonged occlusive exposure for 24 hours led to slightly to moderate erythema (primary irritation score: 1.5/8.0, reversible within 7 days) (Monsanto Co. 1984c).

Eye

Non-human information

The eye irritating potential of 4-ADPA was examined in one study according to OECD Guideline 405. In this Guideline study (OECD TG 405) 0.1 g of 4-ADPA (solid substance) was applied in the conjunctivial sac of 3 rabbits and the eyes were rinsed with physiological saline after 24 hours. The eyes were examined 24, 48, and 72 hours after the administration of the test substance. Corneal opacity, conjunctivial redness and chemosis were observed in all treated animals at 24 and 48 hours. All ocular effects were fully reversible within 72 hours. A primary irritation score of 8.1/110 was determined (Bayer AG 1882b).

In another guideline study moderate ocular irritation from one hour to three days was noted in each of 6 rabbits after instillation of 0.1 ml of finely ground 4-ADPA into the conjunctival sac (Monsanto Co. 1984). Three animals exhibited corneal opacities or ulceration. Four of the six animals had conjunctival redness >2, calculated as the mean scores following grading at 24, 48 and 72 hours after installation of the test substance. All six animals were free of ocular effects within 7 to 14 days (Monsanto Co. 1984d).

The reason for the discrepancy between the results of the two available studies is not known.

Effects on eye irritation: moderately irritating

Justification for classification or non-classification

Based on the findings of the eye irritation study (Monsanto Co 1984d) 4 -ADPA is classified as irritating to eyes according to the classification criteria of regulation no. 1272/2008 (GHS).