One of the metabolites of diflubenzuron, 4-chloroaniline, has been classified by the United States Environmental Protection Agency as a probable human carcinogen.

Nitration of chlorobenzene and related derivatives and reduction of the nitration products gives aniline derivatives, e.g. 4-chloroaniline.

Octenidine is currently increasingly used in continental Europe as a QAC's and chlorhexidine (with respect to its slow action and concerns about the carcinogenic impurity 4-chloroaniline) substitute in water- or alcohol-based skin, mucosa and wound antiseptic.