Effects of Simultaneous Exposure to Formaldehyde Vapor and Noise on Mouse Testicular Tissue and Sperm Parameters

Background: Workers are often simultaneously exposed to formaldehyde and noise in workplaces, and noise can reinforce the harmful effects of some chemical pollutants. Objectives: This study aimed to investigate the effects of simultaneous formaldehyde and noise exposure on reproductive parameters in male mice. Materials and Methods: Forty eight National Medical Research Institute adult male mice were randomly assigned to control and experimental groups which were exposed to formaldehyde (10 ppm) (F), noise (100 dB) (N), and simultaneous formaldehyde with noise (NF), respectively for 10 days (8 hours a day). Animals were killed 24 hours following exposure (short-term effects) and the remainder was killed 35 days after the end of exposure (long-term effects). Sperm was analyzed by a computer aided sperm analysis system and histological changes in the testis were determined. Plasma concentrations of testosterone, LH, FSH were measured. Results: The results of the short-term analysis showed that serum testosterone in all exposure groups decreased significantly compared to the controls (P 0.001). In the longterm analysis, the percentages of progressive motile sperm groups N, F, and NF were 33.73 ± 3.4, 26.65 ± 1.61, and 14.78 ± 4.65, respectively, which indicated a significant decrease (P 0 .05) compared to the control group (44.47 ± 2.88). The progressive motile sperm in the simultaneous exposure group was less than the N and F groups (P 0.001). Histological study of testes specimens in the experimental groups (F and NF) revealed displacement of germinal cells and degeneration of Leydig cells and seminiferous tubules. Conclusion: Exposure to formaldehyde vapor can destroy testicular structure and decrease percentages of sperm count and progressive motility. The present study indicated that a reduction in the percentage of progressive motile sperm may be potentiated by noise (700-5700 HZ) in the simultaneous exposure to formaldehyde and noise group. Thus, it can be anticipated that simultaneous exposure to formaldehyde and noise in workplaces can increase the possibility of damage to testicular structures and reproductive functions in humans, if the same effects transpire.