INCIDENCE AND IMPORTANCE OF PRIMARY IRRITANT AND ALLERGIC CONTACT-DERMATITIS DUE TO MACHAERIUM-SCLEROXYLUM TUL (PAO FERRO), A SUBSTITUTE FOR BRAZILIAN ROSEWOOD (DALBERGIA-NIGRA ALL)

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 33  (6) , 321-328
Abstract
In recent years an increasing number of cases of primary irritant and allergic contact dermatitis has been observed using the South American timber Pao ferro (M. scleroxylum). Since 1978, 140 cases have been reported. The patients were mainly cabinet and furniture makers occupied in the sanding of veneer. Perioral dermatitis and cheilitis were also observed in persons playing the flute made of Pao ferro wood. Guinea pig sensitization experiments revealed a strong sensitizing capacity of the main wood constituent R-3,4-dimethoxydalbergione. Amounts of up to 2% were found in the heartwood. Mix-up of Brazilian rosewood (D. nigra) with its substitute (M. scleroxylum) may occur accidentally due to their appearance. A chemical differentiation is easily possible by determination of their constituents: while Pao ferro exclusively contains the strong sensitizer R-3,4-dimethoxydalbergione, the botanically related Brazilian rosewood (and also the East Indian rosewood, D. latifolia Roxb.) yields several other and weaker dalbergiones. In 41 of 55 patients tested epicutaneously with R-3,4-dimethoxydalbergione an acquires sensitivity was demonstrated. The high amount of R-3,4-dimethoxydalbergione in M. scleroxylum is primarily responsible for the outbreak of toxic dermatitis in veneer factories, half of which resulted in a sensitization. The risk of active sensitization is high if epicutaneous tests are carried out with the native wood sut. To avoid active sensitization it is better to test the pure constituent, if available, in a dilution of 0.1%.