OCCUPATIONAL ASTHMA IN ALUMINUM POTROOM WORKERS RELATED TO PREEMPLOYMENT EOSINOPHIL COUNT

Occupational asthma still occurs in aluminium potroom workers despite pre-employment medical selection, The purpose of our study was to iden tify workers with an increased risk of developing ''potroom asthma''. A nested, case-control study was carried out in two Dutch aluminium pr oducing plants, Pre-employment data of 364 potroom workers (182 cases and 182 controls) were analyzed, Cases were workers unable to work bec ause of work-related respiratory disease, meeting the criteria for pot room asthma The selected controls were matched for age, year of starti ng employment and working conditions. Pre-employment eosinophil count was significantly related to the occurrence of potroom asthma, even th ough the mean number of the eosinophils in cases was within the normal range (<275 cells . mm(-3); 0.28 cellsx10(9) . L(-1)). Hence, 39 of t he 45 individuals with blood eosinophil counts in the upper range of n ormal (>220cells . mm(-3); 0.22 cellsx10(9) . L(-1)) developed potroom asthma with time. We conclude that workers without respiratory sympto ms, with normal lung function and normal bronchial responsiveness befo re employment developed potroom asthma Fluoride exposure, combined wit h an elevated eosinophil count, might induce an immunological or cytot oxic process.