mills and bakeries

As part of an epidemiological study among workers exposed to flour total dust and flour aeroallergen concentrations were measured with personal samplers over a workshift in three large bakeries and four flour mills and packing stations. In the bakeries geometric means for total dust concentrations ranged from 04 mglm3 in the bread wrapping area up to 6-4 mg/m3 at the dough brake. The flour aeroallergen concentrations ranged from 45'5 4Ug/m3 in the bread wrapping area up to 252 0,ugWm3 in the confectionary area. In the flour mills and packing stations the concentrations were higher with geometric means for total dust ranging from 0.5 mglm3 in the office up to 16-9 mglm3 for hygiene workers in an old mill. The flour aeroallergen concentrations ranged from 101.5 4UgIm3 for transport workers up to 1728-2 4UgIm3 for hygiene workers. The relation between total dust and flour aeroallergen concentrations varied for different areas and depended on the use of products other than flour. (Occup Environ Med 1994;51:584-588) Department of Occupational and Environmental Medicine, National Heart and Lung Institute, Royal Brompton and National Heart Hospital M J Nieuwenhuijsen C P Sandiford D Lowson RD Tee KM Venables J C McDonald A J Newman Taylor Correspondence to: Mark J Nieuwenhuijsen, Department of Occupational and Environmental Medicine, National Heart and Lung Institute, 1B Manresa Road, London SW3 6LR, UK. Accepted for publication 18 March 1994 As part of a seven year prospective longitudinal epidemiological study to explore the relation between occupational exposure to flour and respiratory, eye, and skin symptoms, and skin sensitivity we measured personal exposure to total dust and flour aeroallergen in several British flour mills and bakeries. The first results have been reported in a companion paper.' This paper describes the intensity measurements used to provide exposure estimates for subjects in the epidemiological study, and the relation between total dust and flour aeroallergen concentrations. Bakers' asthma was described in antiquity2 and remains among the commonest causes of occupational asthma in Britain today.3 Several studies have shown that flour inhaled at work can cause specific immunological changes, respiratory symptoms, and asthma, and that an increase in duration and intensity of exposure was associated with an increase in prevalence of symptoms and sensitisation.47 Flour and its additives contain many antigens89 but as an assay to measure flour antigens has been developed only recently,' 01' total dust concentration has been used as a surrogate.46 In a study of one bakery'0 flour aeroallergen only showed a relation with total dust at concentrations above 5 mg/M.3 The few studies that have published concentrations of flour dust showed considerable differences in exposure levels between jobs and tasks in different areas of flour mills and bakeries.4 612-15 Material and methods EXPOSURE MEASUREMENTS We surveyed three large modem British bakeries (between 200 and 450 employees each), three flour mills with flour packing stations (60-200 employees each), and a flour packing station (30 employees). All three generally operated for 24 hours a day in several shifts. An occupational hygienist (MJN) visited each site and divided the employees into exposure groups, 11 in each flour mill and packing station and 15 in each bakery, using the zoning strategy described by Corn and Esmen16 and the uniform task categories described by Esmen.'7 A detailed description of the exposure groups has been given elsewhere.18 In both the bakeries and flour mills we created a miscellaneous group for employees who could not be assigned to one of the other exposure groups. In general, the work done was well defined by job title except in the confectionary area of the bakeries. These areas were divided into three, which we refer to as: the "dough brake", "confectionary/flour involved", and "confectionary/no flour". The second of these included the oven men and the third the finishing area behind the oven. A random sample of workers of one shift of each exposure group, measured on different days with sufficient numbers to include at least one worker of the 10% highest exposed, were invited to wear a personal sampler (Casella AFC 123, Casella London Ltd., Bedford) for a whole workshift. The personal samplers were connected to seven hole sampling heads (Casella London Ltd, Bedford) containing polytetrafluoroethylene (PTFE) filters (1 2 gum pore size, 25 mm diameter; Sartorius Instruments Ltd, GB-Belmont, Surrey) at a flow rate of 2 I/min. For total dust measurement the filters were weighed before and after sampling on a six figure balance (Sartorius R18OD; Sartorius Instruments Ltd, GB-Belmont, Surrey) and returned to the laboratory for elution and flour aeroallergen quantification. The limit of detection for dust was 0-12 mg and for flour aeroallergen 1 ug/ml. The coefficient of variation, measured with stationary samples, was 15-5% for 584 group.bmj.com on October 19, 2017 Published by http://oem.bmj.com/ Downloaded from