A two-tailed v2 test of independence was used to determine
whether or not the test item had any significant association with respiratory symptoms between rice mill workers and control subjects. A two-tailed v2 test of independence was also used to determine the respiratory symptoms of the rice mill workers according to the duration of exposure. Student’s
t test was used to determine whether there are any significant differences between the lung function values of
rice mill workers and control subjects. One-way ANOVA and post hoc analysis were used to determine the lung
function values of the rice mill workers according to the duration of exposure. Student’s t test and Chi-square test
were also used to determine the difference of hematological and immunological parameters and radiological findings between rice mill workers and control subjects,
respectively. Statistical analysis was performed using the statistical package PRIMER OF BIOSTATISTICS (Primer
of Biostatistics 5.0.msi, Msi Version 1.20.1827.0, Primer for Windows, McGraw-Hill).