ABSORPTION OF SOME PHENYLENEDIAMINES THROUGH SKIN OF DOGS

m- and p-Phenylenediamines and 2,5-diaminotoluene were applied to the skin of dogs in gels and fluids such as are used in hair dyeing. The absorption of the diamines through the skin was calculated from the concentrations determined in the blood or the amounts excreted in the urine. From 50 ml of a gel containing 1.5 g p-phenylenediamine 16 mg of the diamine was calculated to be absorbed in 3 hours through a skin area of 500 cm2 if free access of air was allowed. Covering the gel with aluminum foil immediately after its application to the skin increased the amount of p-phenylenediamine absorbed to 110 mg. Less than 2 mg of p-phenylenediamine was absorbed if hydrogen peroxide was added to the gel applied to the skin. Amounts of 10-20 mg of p-phenylenediamine were found to be absorbed from a fluid vehicle which contained only 0.3 g of p-phenylenediamine. Bandrowski's base, an oxidation trimer of p-phenylenediamine, was found to be absorbed through the skin. About 40 mg of 2,5-diaminotoluene was absorbed through the skin from gel containing 1.4 g of the material. Addition of hydrogen peroxide to the gel reduced the amount absorbed to less than 3 mg. Small amounts (μg) of unaltered p-phenylenediamine and 2,5-diaminotoluene were found in the urine of dogs to whose skin these amines had been applied. The absorption of m-phenylenediamine through the skin was demonstrated not only by determining its concentration in the blood, but also by the ferrihemoglobin formation that followed the application to the skin. Amounts as large as 60 mg were absorbed from gel containing 1.5 g of m-phenylenediamine. © 1968.