Hematopathology in Sprague-Dawley rats following sub-chronic topical application of para-phenylenediamine

The aim of the present study was to analyze the hematological profile of male SD rats treated topically with aqueous solution of para-phenylenediamine (PPD), a component of almost all hair dye formulations. The rats were painted with different concentration of PPD (0, 1, 2 and 3 mg Kg(-1) Day(-1)) for 90 days and then sacrificed. The hematological profile indicated severe anemia characterized by significant (p < 0.05, 0.001) reduction of total RBC count (59%), packed cell volume (PCV, 50%) and haemoglobin level (70%) in the peripheral blood of PPD treated animals when compared to control group. The leucocytes profile exhibited an overall elevation of around twofold as compared to the control group with significant lymphocytosis (44.4%) and a higher percentage of blast cells (8.5%) as well as smudge (10.3%) and hairy cells (6.2%) in the peripheral blood of treated animals. Histopathological examination of spleen from treated rat's exhibit red pulp congestion, expansion of the germinal centre, hyperplasia of the membrane capsule and extensive accumulation of hemosidderin pigments in the red pulp of the spleen. Overall this study indicated an abnormal pathophysiological condition indicating adverse effect of PPD in the treated animal groups. The risk assessment of hair dye formulation needs to be reviewed in view of widespread usage of paraphenylenediamine in almost all hair dye formulation.