1. Histological changes in the nasal mucosa in rats after long-term exposure to formaldehyde and wood dust
- Author
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Holmstrom, M., Wilhelmsson, B., and Hellquist, H.
- Subjects
Formaldehyde -- Health aspects ,Cancer -- Causes of ,Cancer -- Models ,Laboratory animals -- Research ,Nasal mucosa -- Research ,Emphysema, Pulmonary -- Models ,Wood -- Health aspects ,Health - Abstract
Formaldehyde is a common industrial pollutant used in many industries, but it is usually not the sole irritant in these environments. In the furniture construction industry, formaldehyde, a component of many bonding materials, is usually found in the environment mixed together with wood chips and dust. Both wood dust and formaldehyde are known to be carcinogenic (cause cancer) in man, but little is known about their effects on rodents which are frequently used to test products for humans. The current study assesses the effects on animals in hopes that they may serve as a useful model for human exposure. Young female Sprague-Dawley rats were used, and the animals were placed four to a cage in steel exposure chambers. The animals were divided into groups which were exposed either to formaldehyde, wood dust or a combination of both irritants. An additional group of control animals remained unexposed. The exposure groups spent six hours a day in the chamber for five days a week for 104 weeks. After this experimental period the animals were killed, preserved, and their noses were cut into five pieces 3-5mm thick for observation. Samples of the nasal lining and lungs were prepared for microscopic examination. Although there were no differences in survival time or weight between the groups, animals exposed to formaldehyde showed a yellow discoloration and inflammation of their eyes. One rat in the formaldehyde-only group developed a cancerous nasal tumor (keratinized squamous cell carcinoma); however, this form of cancer occurs frequently in these rats. Statistically significant changes in the microscopic structure of the cells lining the nose, the nasal epithelium, were found largely in areas of the nose that have been associated with formaldehyde-induced tumors. Evidence of emphysema occurred most frequently in animals exposed to wood dust, either alone or with formaldehyde. There appears to be an additive pathological effect of the combined substances on the nasal epithelium of these rodents, which is similar to what has been published about their effects in man. more...
- Published
- 1989