Introduction: We examined the respiratory health of a Danish workforce exposed to man-made vitreous fibres (MMVF) during production.
Material and methods: Workers with more than five years' occupational exposure to MMVF (n = 377) were compared to a group without MMVF exposure (n = 381). Respiratory health was assessed by questionnaire, dynamic spirometry, and measurement of transfer factor. The overall response rate was 63%. A sample of non-responders was assessed by questionnaire and spirometry.
Results: On most spirometric indices, the two groups had comparable values. However, a larger proportion (14.5%) of the exposed subjects had an obstructive flow pattern than the controls (5.3%). Subgroup analyses showed that the elevated risk of airway obstruction associated with exposure was confined to heavy smokers. Transfer factor and prevalences of symptoms and self-reported disease were similar in the two groups.
Discussion: There is no indication of excess risk of lung fibrosis. However, a number of exposed workers have some degree of airflow obstruction, which cannot be explained by known confounders. An additive or synergistic action between smoking and fibre exposure on airflow obstruction can be speculated.