Abstract
A description is given of a hygiene investigation made to determine workers' exposure to airborne microorganisms and antigen in the slicing area of a sugar beet refinery following complaints by the workers of work-related respiratory symptoms. Dust concentrations in the slicing area were not high (up to 3.5 mg/m3), but there Were many airborne microorganisms (200 000 colony forming units/m3), mostly gram-positive bacteria. Of 15 workers, 7 had precipitins to a sugar beet extract. Of these 7, there were 5 who also had precipitins to an extract of dust collected on a ‘Staplex’ filter. There was a line of identity between the beet and dust extracts, indicating the dust contained appreciable quantities of beet antigen. As a result of these findings, local exhaust ventilation was installed before the next slicing season. Further investigations were made near the beginning and end of this second season. The results showed lower dust concentrations and markedly fewer numbers of airborne bacteria. Although total numbers of bacteria fell, numbers of gram-negative bacteria increased and, at the end of the season, comprised 20% of the total bacterial numbers. Specific immunoglobulin G (IgG) concentration in the workers' serums fell between the two slicing seasons and then remained constant through the next slicing season. This reflected the environmental measurements that showed lower dust concentrations after the installation of exhaust ventilation equipment.