Effects of Occupational Formaldehyde Exposure on Passive Avoidance Conditioning and Anxiety Levels in Wistar rats

Background: Formaldehyde is a volatile organic compound widely used in industry and medical fields such as Anatomy and Pathology. Exposure to this chemical negatively affects the skin, mucous membrane, and respiratory system. It can pass through the blood-brain barrier, potentially causing neurotoxicity. According to studies, formaldehyde might be involved in memory impairment and the cognitive decline process in Alzheimer disease (AD). Objectives: This study aimed to simulate chronic occupational formaldehyde exposure in rats and study its impacts on passive avoidance conditioning and anxiety. Methods: Twenty-four adult male Wistar rats were divided into four groups of 6 rats each. After an adaptation period, the rats were exposed to 1, 2, and 3 ppm formaldehyde vapor in an exposure chamber, 6 hours per day for 7 days. The control group was exposed to saline. After the exposure period, a shuttle box for passive avoidance conditioning and an elevated plus-maze test for assessing anxiety levels were performed. The data were analyzed by 1-way ANOVA and Duncan’s multiple range test for group comparison in SPSS and SAS software. Results: In the shuttle box test, formaldehyde dose-dependently decreased escape-through latency and increased the percentage of dark compartment entries (P<0.0001). In the elevated plus maze test, the percentage of time spent in open arms decreased by increasing the dosage (P<0.0001). Conclusion: Based on these findings, formaldehyde exposure can negatively alter brain function and cause memory impairment and anxiety.