Raw materials arrive by ship or by truck. Mainly grains (especially corn, wheat, and barley), other vegetable products such as cassava, tapioca, and waste products from the food industry are used. The raw materials are cleaned, stored in silos, and mixed in a batch process. Fats, molasses, vitamins, and minerals are added in small quantities. The mixture is stored again in silos, usually after being pressed to pellets. The product is transported to the customer by bulk trucks. Only a part of the produced animal feed is packed and transported in bags. Production workers occupied eight job titles as previously described. The job titles involved in production are unloaders, crane drivers, facility operators, press operators, expedition workers, truck drivers, maintenance personnel, and “jacks of all trades.” Fifty-five nonproduction workers, rarely exposed to dust in production processes (laboratory personnel, gate keepers, consultants, office workers), were regarded as controls. Some of these nonproduction workers had previously held production jobs. Maintenance personnel (n=5) were excluded from the study since they may have been exposed to other respiratory hazards, such as welding fumes.
Airborne grain dust was monitored by gravimetric personal air sampling (n=54) of all job titles. A large number of samples (N=17) were taken in the group with “jacks of all trades,” because of the large variability in exposure. Airpumps (DuPont [P-2500]) with PAS-6 filters were used to draw air samples. The sampling rate was approximately 1.2 L/min and the minimum sampling duration was 7.30 h. The filter was positioned near the worker s breathing zone More info canadianfamilypharmacy. Pumps were calibrated immediately before and after each use and monitored throughout the sampling period. The dust sampled is characterized by a 50 percent cut-off diameter of 30 fim12 and resembles the inspirable dust fraction that passes the mouth and nostrils when inhaled. Endotoxin was quantified spectrophotometrically using a modified kinetic-QCL assay (192 Test kit, Bio Whittaker). The method is based on the endotoxin catalyzed activation of a proenzyme in Limulus amoebocyte lysate.