The Relation Between Blood Hemeoxygenase-1 (HO-1) Levels and Lung Function Test in the Stone Mill Employees Who Are Occupationally Exposed to Silica Dust in Upper North Thailand

Abstract

Heme Oxygenase 1 (HO-1) is a new biological marker to indicate lung inflammation with a high accuracy. It has advantage to show a lung pathology caused by silica exposure in rat and silicosis patient. This study was done to determine HO-1 level in 272 stone mill workers. A comparison between HO-1 level and chest x-ray result or lung function was determined. Lung function was determined by Spirometer where as ambient silica was quantified by standard method. Serum HO-1 was measured by Sandwich Enzyme Immunoassay.

Ambient silica mean was 9.24 ± 6.14 mg/m³ which was lower than Thai regulation guideline. The lung pathology was not found by chest X-ray result in any worker. Increase silica exposure level showed a relation to a low lung capacity whereas HO-1 was increased as silica levels increased. HO-1 showed significant correlation to silica levels while a significant correlation between pulmonary function test and silica levels was not observed. These results showed the advantage of HO-1 in a lung pathology indication in the stone mill employees who are exposed to silica dust. This marker should be further developed for early changing of lung physiology indication.