The contact sensitizing potential of
2-(2'-hydroxy-5'-methylphenyl)benzotriazole (
Tinuvin P) was investigated using the murine local lymph node assay (LLNA) and the mouse ear swelling test with some modification in the induction procedure (modified MEST). Topical exposure of the ears to
Tinuvin P in
acetone:
olive oil (AOO) for 3 consecutive days induced no increase in auricular lymph node weight and lymph node cell proliferation. In the LLNA,
Tinuvin P was negative, and its sensitizing potential was determined as not strong. In the modified MEST, mice were sensitized with a combination of an
intradermal injection of 0.2%
Tinuvin P in Freund's complete adjuvant into the shaved abdomen and topical application of 1%
Tinuvin P in AOO on both ears for 3 consecutive days. The ear thickness in mice previously treated with
Tinuvin P increased significantly on challenge with
Tinuvin P. A cross-reaction test between
Tinuvin P and various substituted
benzotriazole ultraviolet light (UV) absorbers was performed. Challenge with these
benzotriazole compounds on the ears of the mice previously sensitized to
Tinuvin P showed no increase in ear thickness. These data indicated that
Tinuvin P had a contact sensitizing ability, while
Tinuvin P-sensitized mice did not cross-react with the other
benzotriazole UV absorbers.