Pyrethrins and pyrethrosin content in commercial allergen extracts

Pyrethrins are the insecticidally active components of pyrethrum extract, derived from flowers of Chrysanthemum cinerariifolium and used in commercial and consumer insecticide products. Most dermal testing performed with pyrethrum extracts was done before current refined pyrethrum concentrate became available (before 1967).

We analyzed presently commercially available pyrethrum allergen extracts to determine the concentration of pyrethrins and the putative sensitizer pyrethrosin.

Six commercial pyrethrum allergen extracts were purchased from four major allergen suppliers and analyzed for pyrethrin I and pyrethrosin by using a capillary gas chromatograph equipped with a flame ionization detector.

The commercial pyrethrum allergen extracts contained no detectable pyrethrins or pyrethrosin. In comparison, the pyrethrum standard provided by the McLaughlin Gormely King Company, a major refiner of pyrethrum, contained 20% pyrethrins and 0.49% pyrethrosin. No compounds observed in the chromatogram of the refined pyrethrum concentrate were present in the allergen extracts.

Caution should be used when interpreting the results of tests performed with current pyrethrum allergen extracts because pyrethrins and pyrethrosin may not be present. Moreover, unknown components such as high-molecular-weight proteins or other impurities that may cause dermal reactions could be present in significant amounts.