Tabriz University of Medical Sciences Health Promotion Perspectives 2228-6497 5 4 2015 12 31 Occupational Exposure and Health Impairments of Formaldehyde on Employees of a Wood Industry 296 303 10.15171/hpp.2015.035 EN Mohammad Javad Jafari Abolfazl Rahimi Leila Omidi Mohammad Hassan Behzadi Mohammad Hassan Rajabi Journal Article 10.15171/hpp.2015.035 2015 04 13 2015 10 04 Background: Occupational exposure to formaldehyde may decrease white blood cell counts and change blood concentration. In this study, the influences of occupational exposure to formaldehyde on the number of white blood cells and blood concentrations were studied. Methods: This case-control study was conducted in June of 2012 at North Wood Factory, Golestan Province, Iran. The US-NIOSH method No. 2541 was used to determine the occupational exposure of 30 workers of the production line (case group) and 30 administrative staffs (control group) to formalde­hyde. The number of white blood cells and blood concentration were determined using the normal blood count method and related indices. Demographic features as well as the symptoms of being exposed to formaldehyde were collected using a standard questionnaire. Results: The occupational exposure of case group ranged from 0.50 ppm to 1.52 ppm. The prevalence of all studied symptoms from formaldehyde exposure in workers (2<median<5; range 1 to 5) was signifi­cantly different (P<0.001) towards the administrative staffs (median 1; range 1 to 4). The number of white blood cells in production line workers was not significantly different from those in administra­tive staff. The average blood concentration in the case group was significantly different from the con­trol group (mean difference= 0.9 [95% CI: 0.40-1.39];P=0.007). Conclusion: Occupational exposure to formaldehyde changed the blood concentration of the studied workers but did not change the number of their white blood cells.