A Novel Multi-Approach Protocol for the Characterization of Occupational Exposure to Organic Dust—Swine Production Case Study

Abstract

Swine production has been associated with health risks and workers’ symptoms. In Portugal, as in other countries, large-scale swine production involves several activities in the swine environment that require direct intervention, increasing workers’ exposure to organic dust. This study describes an updated protocol for the assessment of occupational exposure to organic dust, to unveil an accurate scenario regarding occupational and environmental risks for workers’ health. The particle size distribution was characterized regarding mass concentration in five different size ranges (PM0.5, PM1, PM2.5, PM5, PM10). Bioburden was assessed, by both active and passive sampling methods, in air, on surfaces, floor covering and feed samples, and analyzed through culture based-methods and qPCR. Smaller size range particles exhibited the highest counts, with indoor particles showing higher particle counts and mass concentration than outdoor particles. The limit values suggested for total bacteria load were surpassed in 35.7% (10 out of 28) of samples and for fungi in 65.5% (19 out of 29) of samples. Among Aspergillus genera, section Circumdati was the most prevalent (55%) on malt extract agar (MEA) and Versicolores the most identified (50%) on dichloran glycerol (DG18). The results document a wide characterization of occupational exposure to organic dust on swine farms, being useful for policies and stakeholders to act to improve workers’ safety. The methods of sampling and analysis employed were the most suitable considering the purpose of the study and should be adopted as a protocol to be followed in future exposure assessments in this occupational environment.

Occupational Exposures to Organic Dust in Irish Bakeries and a Pizzeria Restaurant

“…Although a busier bakery, significantly lower fungi concentrations were detected in Bakery 2 (on MEA), but it had higher concentrations of Gram-negative bacteria compared with other sites. Different bioburden profiles were observed (fungi versus bacteria), possibly due to competition among microorganisms, and have previously been observed in similar research on occupational environments [38]. The Gram-negative bacteria and fungi contamination in indoor environments depends on several factors, such as the presence of stagnant water.…”

Antifungal-resistant Mucorales in different indoor environments

“…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).…”

“…Filter pieces were washed with 10 mL of NaCl 0.9% with 0.1% Tween™ 80 (30 min, 250 rpm) on an orbital laboratory shaker, as previously described (Viegas, Faria, de Oliveira, et al 2017b;Viegas, Monteiro, Dos Santos, et al 2018d). Litter (shredded journal paper) and feed (of nonspecified cereal origin) from swine farms, and raw materials (including wheat, corn, malt, rye, barley, oats, malt, carob flours, and non-cereal ingredients such as flavourings and spices, baker's yeast, sugar powder) from bakeries were collected, weighted and processed as previously described (Viegas, Carolino, et al 2013;Caetano et al 2017;Viegas, Faria, et al 2018b). Briefly, 4.4 g of each (not oven-dried prior to processing, thus retaining natural water content) were washed with 40 mL of sterilised distilled water (20 min, 200 rpm) on an orbital shaker.…”

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.…”