Histological changes in the larynx of adult Wistar rats following exposure to cement dust

Cement dust is a fine powder that is produced during the manufacture, handing and use of cement. Previous studies have shown that cement dust causes bronchitis, chronic obstructive pulmonary disease, lung cancer and other lung diseases. Not much has been reported on cement dust exposure on larynx. Therefore, this present study was carried out to investigate histological changes in the larynx of Wistar rats following exposure to cement dust. Twenty-four (24) Wistar rats weighing between 250g and 280g were divided into 4 groups of 6 rats per group. Group A rats were placed in a cement dust free chamber while Group B - D animals were exposed to cement dust dispersed from 5g (low dose), 10g (medium dose) and 20g (high dose) of cement, respectively via dust distributor glass-chamber (DDGC) of dimensions 32.5 cm³ in length, 32.5 cm³ in width and 16.5 cm³ in height for 1 hour daily for 30 days. The weights of the rats were taken weekly, and the difference noted. At the end of the 30th day of exposure, the animals were euthanized under chloroform anaesthesia and the larynges were harvested and processed for histological examination. The histological sections of the larynx of rats in group A revealed normal mucous membrane, muscular layer, cartilage, subepithelial areolar connective tissue and lumen. There were observable histological variations in the laryngeal architecture of the exposed rats (Groups B-D) which include severe mucosal ulceration, sub-epithelial oedema and heavy mucosal infiltrates of inflammatory cells. These injuries are consistent with usual histological findings in laryngitis. It was concluded that cement dust had histomorphological effects on the mucosa, submucosa and muscuaris of the larynx which are capable of compromising the health of the research animals.