(a) The principal display panel of the label and any labeling accompanying a coal tar hair dye containing any ingredient listed in paragraph (b) of this section shall bear, in accordance with the requirements of § 740.2, the following:
Warning - Contains an ingredient that can penetrate your skin and has been determined to cause cancer in laboratory animals.
(b) Hair dyes containing any of the following ingredients shall comply with the requirements of this section: (1) 4-methoxy-m-phenylenediamine (2,4-diaminoanisole) and (2) 4-methoxy-m-phenylenediamine sulfate (2,4-diaminoanisole sulfate).
[44 FR 59522, Oct. 16, 1979]