Recommended changes to standard series.

This article presents changes recommended jointly by the ICDRG and EECDRG to the standard series. While potassium dichromate 0.25% pet. gives less false positive reactions than 0.5% pet. It also misses too many true positive reactions. Of 2939 patients tested in a recent EECDRG multicentre study, 143 reacted to both. In 96, chromate allergy was considered relevant. Since PPD-dihydrochloride 0.5% pet. replaced PPD-base 1% pet. in 1984, the frequency of PPD sensitivities were missed with PPD-dihydrochloride.