Histopathological effect of exposure of Formaldehyde vapour on the trachea and lung of adult wistar rats

The aim of this investigation was to sensitize embalming laboratory users of the impending danger associated with overexposure of 40% formaldehyde vapour (the active chemical in the embalming fluid) on the trachea and lung. Sixty adult male wistar rats were used for this investigation. The animals were divided into five (A, B, C, D and E) groups (n=12). Animals in Groups B, C, D and E were respectively exposed to 40% formaldehyde vapour for fifteen, twenty, twenty-five and thirty days while animals in group A which served as control group were not exposed to 40% formaldehyde at all. At different stages of the experiment, the animals in each of the groups were decapitated and the thoracic cage cut open to expose the trachea and lung. Some of the tissues were excised and assayed for Malondialdehyd (MDA) and catalase activities while some were processed for light microscopic investigation adopting the Heamatoxylin and eosine (H & E) staining procedure. The histopathological observation in our study showed an alteration in the cytoarchitecture of the epithelium of the trachea and lung of the treated animals. These alterations were characterized by ulceration and mataplasia of the trachea epithelium, ulceration of the alveoli, hyperkeratosis, necrotic lesions and desquamation. Also, there was a significant day dependent increment (p<0.05) in the activities of MDA and catalase in the treated animals. These findings confirmed the toxic effect of 40% formaldehyde vapour in the rat trachea and lung and advocate for precautionary measure while handling this chemical.