Pyrethrum dermatitis.II. The allergenicity of pyrethrum oleoresin and its cross-reactions with the saline extract of pyrethrum flowers

Tests on sensitised guinea pigs have indicated that crude pyrethrum oleoresin contains two types of allergens. The more potent are compounds with similar allergenic determinants to the allergens present in the 0.9% saline extract of pyrethrum flowers which have been tentatively classified as glycoproteins or glycopeptides with molecular weights distributed between about 60 000 and 200 000. The second class of allergens is the sesquiterpene lactones, principally pyrethrosin but these are of minor importance due to their low concentration in pyrethrum oleoresin. Contrary to a recent report, no allergenic activity was obtained from pyrethrin II.