RESULTS patch test in relation to allergic contact dermatitis has been fi rmly established in the scientific literature. The documenta-The participation pattern and the sex and age distribution of the participants in 1990 and in 1998 are shown in TableI. tion includes studies on the history of the individuals with positive tests compared with controls, extensive exposure TableI shows the prevalence of allergic contact sensitivity to the individual haptens and mixtures of haptens in the test assessment including chemical analysis and experimental double-blind exposure studies with fragrance chemicals in series in 1990 and 1998 among men and women in the 2 age groups (15–22 and 23–41-year-olds). Table II shows the pre- specifi c sensitized individuals (9–14). Because patch-test reactions were read on day 2 only, the frequencies of sensitization valence of allergic contact sensitivity to one or more hapten, to one or more hapten other than nickel, and to one or more in this study were probably underestimated.