Occupational exposure to bioburden in Portuguese bakeries: an approach to sampling viable microbial load

Abstract

In bakeries, a number of operations such as mixing are associated with exposure to air-suspended flour dust and related bioburden. The aim of this study was to find the best active sampling approach to the assessment of occupational exposure to bioburden in Portuguese bakeries based on the data obtained with the use of specific impaction and impinger devices. We used impaction to collect fungal particles from 100 L air samples onto malt extract agar (MEA) supplemented with chloramphenicol (0.05 %). For growing fungi we also used dichloran glycerol (DG18) agar-based media and for mesophilic bacteria we used tryptic soy agar (TSA) supplemented with nystatin (0.2 %). For Enterobacteriaceae we used violet red bile agar (VRBA). With impingers we also collected 300 L air samples at the 300 L/min airflow rate, inoculated onto the same culture media. The two methods, impaction and impinger, showed statistically significant differences in the following counts: fungal on MEA (z=-2.721, p=0.007), fungal on DG18 (z=-4.830, p=0.000), total bacteria (z=-5.435, p=0.000), and Gram-negative coliforms (z=-3.716, p=0.000). In all cases the impaction method detected significantly higher concentrations than the impinger method. Fungal and bacterial loads were higher in the production unit and lower in the shop. The fungal load obtained with impaction varied between 10 and 5140 CFU m-3, and total bacterial counts ranged between 10 and 4120 CFU m-3. This study has shown that the impaction method is the best active sampling approach to assessing viable bioburden in this specific occupational environment, but a multi-faceted approach to sampling and analyses combining methods and media enables a more refined risk characterisation and, consequently, better tailored risk control measures to reduce adverse health outcomes in workers.

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

“…Indeed, a previous report developed by Brera et.al [61], and including exposure data from three European countries (Italy, Norway, and the United Kingdom) demonstrated that intakes of pasta and pasta-like foods, breakfast cereals and snacks, and bread and bread-like foods and biscuit were significantly associated with a higher level of total DON, adjusted for creatinine. Therefore, contamination is probably coming from the cereal crops, continues in the grain farms where the grains are processed, and stored to produce various products, namely feed and flours [2,3]. Although the present study did not include a human biomonitoring element, a similar conclusion is likely here.…”

“…Settled dust (composed essentially of flour) and organic dust are likely to contribute to the inhalation exposure of mycotoxins. This can happen because of the re-suspension of settled dust, and also from exposure as a result of the high volumes of flour used by the workers in this sector on a daily basis [2,3]. There is currently a knowledge gap concerning the approach, which should be used to accomplish a suitable risk assessment methodology for mycotoxins, as toxicokinetics and toxicodynamics data for mycotoxins from exposure routes other than ingestion are lacking [42].…”

“…Raw extracts were diluted with the same amount of water, and were mixed, filtered, and injected into the LC-MS/MS system (Shimadzu, Tokyo, Japan). Similar methodologies for the detection of mycotoxins were followed to those reported in previous studies [2,3]. Several mycotoxins were targeted in the assessment performed, namely:…”

“…Flour, the basic ingredient in an array of bread and bakery products, is a complex organic dust containing allergens and antigenic particles from constituent cereals, such as wheat, oat, rye, rice, or corn [1]. Along with other raw ingredients commonly used in baking, baker's yeast, bread improvers, and flour can provide an ideal substrate for microbial growth, and can generate high levels of bioaerosols during processing [2,3]. Occupational exposures in this sector can lead to the development of conjunctivitis; contact dermatitis; and debilitating occupational respiratory diseases, including flour induced rhinitis and "baker's asthma", the latter of which is one of the most common work-related respiratory diseases.…”

Characterization of Occupational Exposure To Fungal Burden in Portuguese Bakeries

“…For surface samples, the floors (considered as the most critical surface) of the same indoor locations (production, warehouse and store) were swabbed using a 10 by 10 cm square [10]. Settled dust and EDC sampling approaches were collected and extracted following the procedures previously described [23].…”