of these hair dyes it will be important to take account of smoking habits in any such studies of smoking-related cancers, particularly in view of a recent report suggesting that beauticians have an increased risk of lung cancer.9We thank the consultants who allowed us to interview patients under their care, and the Toilet Preparations Federation and the manufacturers of hair dyes, who helped us by providing information about hair care preparations. We also thank Mr Paul Humphreys, who helped in the analysis of this study, and Mr Peter Smith, Mr Julian Peto, and Sir Richard Doll for their helpful comments.ADDENDUM-The Registrar General has informed us that the latest (unpublished) occupational mortality analysis for 1970-2 shows no appreciable excess of breast cancer in single female hairdressers aged under 65 years-eight observed, seven expected (OPCS, by permission).