612 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS was determined for each subiect participating in long4erm studies. To establish the normal course of dandruff in the absence of therapeutic measures, it was desirable to determine both average levels and the types of fluctuation experienced in particular, it was of interest to look for possible seasonal variations. In a modern community, virtually everyone's scalp receives "treatment" by way of a shampoo two panels were therefore established, to compensate for possible effects on dandruff due to the shampoos. One panel used an anionic shampoo based on an alkanolamine-neutralized sulphated fatty alcohol and the other a reputedly non-irritant preparation based on an ethoxylated fatty acid soap. Each subiect was supplied regularly with the shampoo and any other hairdressing products needed, e.g. hair-sprays, wave-set, hair cream. By the end of the full study, the first panel comprised 3 men and 13 women, and the other 1 man and 10 women. The groups were balanced approximately with respect to average dandruff levels before the experimental period began. The investigation continued for at least 15 months on each subiect, with scalp examinations fortnightly. 4O 3O I¸ i i i i i I i .i i i Jan Feb March April May June July Auqust Sept Oct Nov Dec Figure g Individual dandruff graph. Specimen graphs showing dandruff index as a function of time are shown in oeigs. 2 and $. The records were analysed for seasonal variation and for other fluctuations about the average dandruff level for individual sub- jects. If any substantial seasonal variation had occurred within 12 months,

THE INVESTIGATION OF DANDRUFF 613 F4ey June July Auc/uif Sept Oct Nov Dec Jori Feb Morck April Figure 8 Individual dandruff graph (showing marked fluctuations). the dandruff index averaged each month over all subjects should have shown this. Data from the same 12-month period, for 12 members of the "anionic" panel and 8 members of the other panel is illustrated in Fig. 4. :z MONTH • Ethoxylated Soap Shampoo, 8 subjects O Anionic Shampoo, 12 subjects Figure 4 Dandruff index in study of seasonal variation.