INTERPLAY OF CIGARETTE-SMOKING AND OCCUPATIONAL EXPOSURE ON SPECIFIC IMMUNOGLOBULIN-E ANTIBODIES TO COBALT

The results of a cross-sectional survey of an occupational population (n = 706) exposed to hard metal dust revealed distribution of specific immunoglobulin E antibodies against cobalt-conjugated serum albumin ( Co-HSA). This population was segregated with respect to smoking and du st-exposure doses. Standard deviations (0.08-0.13) of Co-HSA RAST were sufficiently small (< 7%) to warrant reproductibility. Confirming evi dence for 8 workers who had mean + 3 standard deviations of Co-HSA RAS T indices and who had been diagnosed with occupational asthma also pro vided better sensitivity (8/19) and specificity (687/687) of hard meta l asthma, rather than metal-induced asthma. Cobalt exposure resulted i n significant increases in Co-HSA RAST indices in males, whose mean in dex was 1.16 +/- 0.13 in nonexposed subjects and 1.37 +/- 0.13 in expo sed subjects. There was no difference, however, in the females. This d ifference between males and females cannot be explained by differences in ages or dust-exposure doses. Furthermore, the specific RAST indice s against Co-HSA displayed a strong correlation not only to the intens ity of cobalt exposure (r =.488, p <.001), but to log(total exposure d oses) (r =.578, p <.001). These results suggest that Co-HSA RAST might be useful as a biological marker for the allergic etiology of hard me tal asthma. Nonexposed smokers had similar mean RAST indices: 1.18 +/- 0.12 IU/ml, compared with 1.15 +/- 0.16 IU/ml for nonexposed subjects who had never smoked. There was no correlation between Brinkman indic es (i.e., number of cigarettes/d x y) and RAST indices in any of the m ale groups. Higher, but not significant, mean RAST indices were found for ex-smokers in both the nonexposed (1.18 +/- 0.14) and exposed subj ects (1.26 +/- 0.12), compared with subjects who had never smoked. Ser um immunoglobulin E levels in the ex-smokers declined with age after t hey quit smoking, irrespective of exposure status. In contrast, hard m etal (cobalt) exposure elevated specific immunoglobulin E. The results of the study suggest that elimination of hard dust exposure is more i mportant than cessation of smoking in the minimization of risk of bron chial asthma. Hard metal exposure may be a preventable risk factor for occupational asthma.