Diphenylguanidine (DPG) has been used as a primary and secondary accelerator in the vulcanization of rubber. Exposure to DPG may occur as a result of dermal contact during rubber manufacture or from contact with the finished products. DPG is poorly absorbed through skin. It can be found in latex gloves and other rubber products found in homes and offices. Diphenylguanidine is a standardized chemical allergen. It is used for diagnosis of contact allergy. It is a component of Carba Mix, used in the epicutaneous patch test, called T.R.U.E. TEST, approved by FDA in 1994. T.R.U.E. TEST is indicated for use as an aid in the diagnosis of allergic contact dermatitis in persons 18 years of age and older whose history suggests sensitivity to one or more of the 35 substances included on the T.R.U.E. TEST panels.

(E)-Isoeugenol is crystalline while compound with spice clove type odor. The melting point of E-isoeugenol is 33°C. E-Isoeugenol has been shown to cause contact and allergic dermatitis in humans. Positive skin patch tests in numerous individuals have confirmed the sensitizing ability of isoeugenol.

p-tert-butylphenol is in public use since the 1930s. It is used as an intermediate in the manufacture of varnish and lacquer resin. It has apparently not been reported to occur in nature. There is an abundant literature dealing with the well-established sensitization and depigmentation (vitiligo) properties of p-tert-butylphenol.

(E)-Isoeugenol is crystalline while compound with spice clove type odor. The melting point of E-isoeugenol is 33°C. E-Isoeugenol has been shown to cause contact and allergic dermatitis in humans. Positive skin patch tests in numerous individuals have confirmed the sensitizing ability of isoeugenol.