This study was conducted to evaluate the ventilatory function in shipyard welders using the lifetime cumulative exposure to welding fumes.

Ventilatory function tests were performed on 241 male welders at one large shipyard,exposed to welding fumes for over five years,and was compared to 80 male control subjects. Ventilatory function indices, such as forced vital capacity(FVC), one-second forced expiratory volume(FEV 1), ratio of FEV 1 to FVC(FEV 1%), maximal mid-expiratory flow(MMF), peak expiratory flow rate(PEFR)and maximal expiratory flow at 50 and 75% of expired FVC(FEF50 and FEF75), were obtained by analyzing forced expiratory spirograms and maximal expiratory flow-volume curves that were simultaneously measured by an Impulse ocillometry(IOS)program in the standing position.

FEF50 and FEF75 expressed as a percentage of the predicted values were significantly lower in the exposure group than in the controls, and the MMF tended to decrease.The means of all the ventilatory indices,expressed as percentage of the predicted values, were not significantly increased at the current exposure levels. The MMF, FEF50 and FEF75, expressed as a percentage of the predicted values, were significantly decreased with an increase in exposure duration.Only the FEF75 , expressed as a percentage of the predicted value, was significantly decreased with an increase in the cumulativeexposure to welding fumes(C1). The FEF75, expressed as a percentage of the predicted value, was significantly decreased with an increase in the cumulative exposure to welding fumes(C2). The above parameters were calculated to consider the current exposure level, exposure duration, application of the ventilatory system, production rate, personal protection evice, electrode and welding wire. The MMF and FEF50, expressed as a percentage of the predicted value, tended to decrease. The proportion of workers with abnormal MMF, FEF50 and FEF75 were significantly increased with an increase in the cumulative exposure to welding fumes(C2).

These findings suggested that the MMF, FEF50 and FEF75 are sensitive and practical indices for the evaluation of the ventilatory function of workers exposed to welding fumes, when the lifetime cumulative exposure(C2) is considered as a factor affecting exposure.