Electrostatic Dust Cloth: A Passive Screening Method to Assess Occupational Exposure to Organic Dust in Bakeries

Abstract

Organic dust is widespread in the environment including occupational settings, such as bakeries. Recently, a new collection device-the electrostatic dust cloth (EDC)-has been described for the assessment of occupational exposures. The aim of this study was to investigate the suitability of EDC for identifying the distribution patterns and exposure concentrations of particulate matter and microbial contaminants such as fungi and bacteria in bakeries. Twelve bakeries were selected, and dust was allowed to settle for 13 to 16 days on EDCs (a total of 33 samples). Particle counts and size distribution (0.3 µm, 0.5 µm, 1 µm, 2.5 µm, 5 µm and 10 µm) were measured with direct-reading equipment. Higher EDC mass was significantly correlated (p values < 0.05) with higher fungal load on dichloran glycerol (DG18) and with particle size distribution in the 0.3 µm, 0.5 µm, 1.0 µm and 10.0 µm range. Fungal levels on malt extract agar (MEA) ranged from 0 to 2886 CFU/m 2 EDC in the warehouse setting, 0 to 500 CFU/m 2 EDC in the production setting, and 0 to 3135 CFU/m 2 EDC in the store. Penicillium sp. (42.56%) was the most frequent fungi. Total bacterial load ranged from 0 to 18,859 CFU/m 2 EDC in the warehouse, 0 to 71,656 CFU/m 2 EDC in production, and 0 to 21,746 CFU/m 2 EDC in the store. EDC assessment provided a longer-term integrated sample of organic dust, useful for identifying critical worksites in which particulate matter and bio-burden exposures are elevated. These findings suggest that EDC can be applied as a screening method for particulate matter-exposure assessment and as a complementary method to quantify exposures in occupational environments.

Antifungal-resistant Mucorales in different indoor environments

“…The use of passive methods in this study allowed the determination of fungal contamination levels indoor for both total and azole resistant mycobiota, and the specific identification of Mucorales, from a broad period of time (weeks to several months), whereas active methods (short-term air sampling) could only reflect the load from a shorter period of time (mostly minutes) with large spatial and temporal variations (Hyvärinen et al 2001;Viegas et al 2018c). When possible, different sampling methods should be used in combination, to avoid having to rely in a single method and to represent a long-term time period-integrated scenario (Leppänen et al 2018).…”

“…Mucorales isolates were obtained from samples collected at independent projects aiming for the assessment of occupational exposure and indoor air quality, focusing on exposure to bioburden. Indoor environmental samples were collected between 2013 and 2018 from four different occupational settings around Lisbon metropolitan area, and from dwellings in Aveiro region (Portugal) (Table 1), as follows: bakeries (Caetano, Faria, et al 2017;Caetano, Zegre, et al 2018;Viegas et al 2018c), swine farms (Viegas, Carolino, et al 2013;Viegas, Faria, Dos Santos, et al 2016b;Viegas, Faria, Monteiro, et al 2018b), taxis used for patient transportation (Viegas et al 2018d), waste-sorting plants (Viegas, Gomes, et al 2014;Viegas, Faria, Dos Santos, et al 2015;Viegas, Faria, Caetano, et al 2017a), and dwellings (data not published). In order to collect and assess total bioburden and resistant mycobiota, different sampling devices were used per setting that were better adapted to the activities developed in each environment: electrostatic dust collector (EDC) from dwellings and bakeries; filters from the air-conditioning system of vehicles (taxis and waste fork lifters); litter and feed from swine farms; raw materials from bakeries (Table 1).…”

“…EDCs with a surface exposure area of 0.00942 m 2 were placed at a minimum 0.93 m above floor level, and dust was allowed to settle for, at least, 15 days in bakeries and 30 days in dwellings. After sampling, EDCs were weighted and washed with 20 mL NaCl 0.9% with 0.05% Tween™ 80 by orbital shaking (250 rpm, 60 min) (Edmund Bühler SM-30, Hechingen, Germany) (Caetano et al 2017;Viegas et al 2018c).…”

Aspergillus collected in specific indoor settings: their molecular identification and susceptibility pattern

“…Air samples (active sampling) were collected through an impaction method with a flow rate of 140 L/min (Millipore air Tester, Millipore, Billerica, MA, USA) onto each plate according to manufacturer's instructions. Passive methods [(surfaces, electrostatic cloth devices (EDC), air conditioning filters and feed samples)] were applied to each indoor environment, as previously described (Viegas et al 2018a(Viegas et al , 2018b(Viegas et al , 2018c. Samples were collected from the following environments: taxis' air conditioning filters (N = 19; 28 personal vehicles used as controls), fork lifters' air conditioning filters (N = 11) of a waste industry, dairy farm (N = 1), veterinary clinic (N = 1), dwellings (N = 28), faculty environment (N = 1) and bakeries (N = 13) ( Figure 1).…”

“…Cultures were performed as previously described (Madsen et al 2012;Viegas et al 2018aViegas et al , 2018bViegas et al , 2018c. Inoculated samples were inoculated onto Malt Yeast Agar Extract (MEA) (Oxoid, Hampshire, United Kingdom), Sabouraud Dextrose Agar (SDA) (Oxoid, Hampshire, United Kingdom) and Dichloran Glycerol Agar Base (DG18) (Oxoid, Hampshire, United Kingdom) and incubated at 27°C for 5-7 days in order to allow the growth of all fungal species present in the samples.…”