Lawsonia inermis and paraphenylenediamine exerts an insidious effect on the epidermal, renal, and hepatic tissue with repeated application: a histological and morphometrical study

Ground leaves of Lawsonia inermis (LI) made into a paste has been used from the Bronze Age as cosmetic application. Para-Phenylenediamine (PPD) is an organic compound that is added to LI to increase its aesthetic appearance and longevity. Addition of PPD increases the possibility of allergic contact dermatitis from LI tattoo combinations, and may be absorbed through the skin, affecting body organs. The current study was conducted to determine the effect of this mixture on the histology of skin, liver and kidney tissue. Thirty albino rats were grouped into five groups. The treatment protocol included a control group (I), application of LI paste alone for a period of two weeks (II), and four weeks (III), and a combination of LI and PPD for two weeks (IV), and four weeks (V). All rats in each group had an area on the lumbar region shaved and marked, and the paste was applied to this region. The rats were sacrificed after the experimental period and the tissues of interest removed for further histological and morphometric analysis. Application of LI alone caused no observable histological changes, however, in combination with PPD, LI caused thinning of the epidermis, reduction in the quantity of collagen fibers in the dermis, distorted the arrangement of hepatocytes, caused infiltration of inflammatory cells into the liver tissue and distortion in the arrangement of renal tubular epithelial cells. The longer the exposure to LI and PPD, the more alteration to the normal histology of tissues.