TT #219 · Parshas Tazria · Aliyah 5 · Passuk 39
English: the priest shall examine them. If the spots are dull white, it is a harmless bohak that has appeared in the skin; he is clean.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:39
Torah Temimah cites Sifra (Toras Kohanim) for the pure status of bohak.
Sifra — Vayikra 13, Midrash Sefer
English: 'It is bohak; he is clean' teaches that bohak is pure.
Textual derivation
The pale spots called bohak are not themselves a source of impurity.