Personal dust exposures at a food processing facility

A field study was performed to quantify personal dust exposures at a food processing facility. A review of the literature shows very little exposure information in the food processing industry. The processing area consisted of a series of four rooms, connected by a closed-loop ventilation system, housed within a larger warehouse-type facility. Workers were exposed to various fruit and vegetable dusts during the grinding, sieving, mixing and packaging of freeze-dried or air-dried products. Eight two-hour periods were monitored over two days. Personal total suspended particulate samples were collected on 37 mm PVC filters with 5 microm pore size according to National Institute for Occupational Safety and Health (NIOSH) Method 0500. The filters were analyzed gravimetrically. The two-hour task sampling personal dust exposures ranged from 0.33-103 mg/m3. For each worker, an eight-hour time weighted average (TWA) concentration was calculated, and these ranged from 3.08-59.8 mg/m3. Although there are no directly appropriate occupational exposure limits that may be used for comparison, we selected the Threshold Limit Value (TLV) for particulates not otherwise classified (PNOC) of 10 mg/m3 for inhalable particles. Neglecting the respiratory protection used, five out of eight of the worker time-weighted averages exceeded the TLV. It should be noted that the TLV is based on the inhalable fraction and in this study total suspended particulate was measured; additionally, the TLV is applicable for dusts that are insoluble or poorly soluble, and have low toxicity, which may have limited protective ability in this case due to the irritant nature of certain dusts (e.g., jalapeno peppers, aloe vera). Sieving resulted in significantly higher exposure than grinding and blending. Measuring area concentrations alone in this environment is not a sufficient method of estimating personal exposures due to work practices for some operations.