Sensitisation to enzymes in the animal feed industry

Objectives - To assess the prevalence of enzyme sensitisation in the animal feed industry. Methods - A cross sectional study was conducted in four animal feed factories, where several enzymes had been used in powder form for 7-9 years. Before this study, enzymes in liquid form had started to be used. Sensitisation to enzymes was examined by skin prick and radioallergosorbent (RAST) tests. Altogether 218 workers were tested; 140 people in various tasks in manufacturing, where exposure to various organic dusts and to enzymes was possible, and 78 non-exposed office workers. The workers were interviewed for work related respiratory and skin symptoms. Total dust concentrations were measured by a gravimetric method. The concentrations of protease and a-amylase were measured with catalytic methods and that of xylanase with an immunological method. Results - Ten workers (7%) were sensitised to enzymes in the exposed group of 140, whereas none were sensitised in the non-exposed group. Six of the sensitised people had respiratory symptoms at work: two of them especially in connection with exposure to enzymes. Enzyme concentrations in the air varied greatly: xylanase from less than 0.8 ng/m(3) up to 16 ng/m(3), a-amylase from less than 20 ng/m(3) up to 200 ng/m(3), and protease from less than 0.4 ng/m(3) up to 2900 ng/m(3). On average, highest xylanase and a-amylase concentrations were found in the various manufacturing sites, whereas the highest protease concentrations were found in areas of high total dust. Conclusions - Industrial enzymes may cause allergies in the animal feed industry. There is a need to assess exposure to enzymes at various phases of production, and to minimise exposures.