Objective: To perform follow-up of lung function and respiratory and ocular symptoms in foundry workers exposed to monoisocyanates using the Hot Box method.
Methods: Four years after an initial assessment, 25 foundry workers and 55 referents completed a questionnaire and were assessed by spirometry pre- and postshift. Exposure to isocyanic acid, methyl isocyanate, and formaldehyde was measured.
Results: Exposure levels were reduced by 50% at follow-up. A high prevalence of nasal and ocular symptoms remained in both groups, but lower airway symptoms had decreased. Lung function preshift was lower for the exposed group, but lung function over shift was unaffected.
Conclusions: The high prevalence of nasal symptoms and the small reduction of forced expiratory volume in 1 second preshift in exposed foundry workers at follow-up may indicate a prolonged influence of previous exposure in the working environment despite reduced exposure levels at follow-up.