Changes to the European standard series which have taken place since t
he last officially recommended alterations in 1988, are explained. New
to the series is the sesquiterpene lactone mix. The PPD black rubber
mix and the quinoline mix have been replaced by single components; one
of the p-hydroxybenzoates has been left out of the paraben mix. Ethyl
enediamine dihydrochloride has been dropped from the series.