Respiratory effects due to occupational exposure to formaldehyde: Systematic review with meta-analysis

Subjects exposed to organic solvents frequently complain of respiratory symptoms. Epidemiological studies conducted in these exposed subjects with special reference to respiratory effects are very few and that too are on very small number of subjects. This paper critically reviews most of the epidemiological studies in formaldehyde induced respiratory effects and combines them through meta analysis to get global precise estimates of the respiratory risks. A computerized bibliographic search revealed 16 epidemiological studies out of which 12 studies were considered for meta analysis. The symptoms of upper respiratory tract were more prevalent as the combined odds of exposed was 5.04 compared to controls. The pooled odds ratio for acute lower respiratory symptoms ranged between 1.85 and 2.91. The mean fall of FVC, FEV1 and FEV1/FVC was only 3.4%, 3.6% and 0.6% respectively, which was not statistically or physiologically considered significant.