CHANGE IN OBSTRUCTIVE PULMONARY-FUNCTION AS A RESULT OF CUMULATIVE EXPOSURE TO WELDING FUMES AS DETERMINED BY MAGNETOPNEUMOGRAPHY IN JAPANESE ARC WELDERS

Objectives-To examine the effect of chronic exposure to welding fumes on pulmonary function by a direct estimate of fumes accumulated in the lungs. Methods-The strength of the residual magnetic field of externa lly magnetised lungs (LMF) was used as an estimate of fumes accumulate d in the lungs. The results of forced spirometry manoeuvres obtained i n 143 of 153 male welders in the original sample were cross sectionall y evaluated according to LMF. Seven conventional forced spirogram indi ces and two time domain spirogram indices were used as pulmonary funct ion indices, and height squared proportional correction was performed when necessary. Results-The distribution of LMF values was considerabl y skewed towards positive. There was a weak but significant positive r elation between age and log transformed LMF. Obstructive pulmonary fun ction indices correlated well with LMF After adjustment for age and sm oking, however, a significant association with LMF was only found with percentage rate of forced expiratory volume in one second (FEV1%) div ided by forced vital capacity (FVC) and mu, an average component of as sumed time constant distribution of lung peripheral units. Neither FVC nor vital capacity (VC), as indices of restrictive disorders, showed a significant association with LMF. Based on the results of multiple r egression analyses, a 0.6% decrease in FEV1% and 0.039 unit increase i n mu were expected for each doubling of LMF. Conclusion-Obstructive ch anges in pulmonary function were found to be related to level of cumul ative exposure to welding fume in male Japanese are welders after cont rolling for age and smoking, assuming that LMF adequately reflects acc umulation of welding fumes in the lungs.