Study objectives: To detect an adverse effect of chronic inhalative molybdenum trioxide (MoO3) exposure in a group of symptomatic MoO3 exposed workers.
Participants: 43 inhalatively MoO3 exposed workers of a metal plant and 23 non-exposed controls were included in this study. Among the workers, 33 suffered from respiratory symptoms while 10 individuals were asymptomatic.
Interventions: Chest x-ray, spirometry and bronchoalveolar lavage (BAL) were performed using standard equipment.
Measurements and results: Neither symptomatic nor asymptomatic MoO3 exposed workers showed firm radiological signs of interstitial lung disease. In lung function testing, symptomatic MoO3 exposed workers did not differ from their asymptomatic colleagues. Employees of the metal plant had a higher percentage of predicted forced expiratory volume in 1 second (FEV1 %) and a higher percentage of predicted forced vital capacity (FVC %) than controls (p<0.05). In BAL cytology, symptomatic MoO3 exposed workers showed higher percentage counts of lymphocytes (p < 0.001) and neutrophils (p < 0.01), and higher T4/T8 ratios (p < 0.01) than asymptomatic MoO3 exposed workers. Furthermore symptomatic workers showed higher percentage counts of lymphocytes (p < 0.05) and neutrophils (p < 0.05) than individuals of the control group.
Conclusion: The results of BAL cytology in symptomatic workers may be interpreted as a MoO3 induced subclinical alveolitis. This may indicate an adverse effect of chronic inhalative MoO3 exposure. It remains unclear whether symptomatic MoO3 exposed workers are at risk for the development of an interstitial lung disease in the future.