Histology of the Airways Following Chronic Exposure to Formaldehyde in Wistar Rats

Histology of the airways and tissues of the lungs following chronic exposure to formaldehyde was studied in wistar rats. The wistar rats were divided into three groups A, B and C with five animals in each group. Group A served as control with nil exposure while groups B and C were the test groups with 5 months exposure on non-dissection days and dissection days respectively. Formaldehyde air level was measured both at experimental and control sites. Histology of the nasal mucosa, tracheal mucosa, and lungs was carried out for each group. Statistical analysis on formaldehyde air level was done using Graph Pad Prism version 5.0. Results were presented as Mean ± SEM. Analysis of Variance was used to compare the means of test and control values while post hoc test was done using Student Newman Keul's test and a P-value of less than 0.05 was considered as statistically significant. Results from histology revealed severe erosion of the cilia and ulceration of the epithelium as well as infiltration of inflammatory cells, edema and dilation of glands. In conclusion, exposure to formaldehyde is shown to have deleterious effects on the airway epithelium of wistar rats and this may be a reflection of what could possibly happen in humans hence there is a need to seek ways of reducing formaldehyde exposure levels especially among people that work in places where formaldehyde is continuously utilized.

Key Words: epithelium, airways, formaldehyde, cilia, wistar rats