Microbial contamination in waste collection: Unveiling this Portuguese occupational exposure scenario

Comprehensive analysis of particulate matter, gaseous pollutants, and microbiological contamination in an international chain supermarket

Indoor environmental quality is of utmost importance since urban populations spend a large proportion of their life in confined spaces. Supermarkets offer a wide range of products and services that are prone to emitting several air pollutants. This study aimed to perform a comprehensive characterisation of the indoor and outdoor air quality in a multinational supermarket, encompassing not only criteria parameters but also unregulated pollutants of concern. Monitoring included measurements of comfort parameters, CO2, multiple gaseous pollutants, particulate matter (PM10) and bioburden. PM10, volatile organic compounds (VOCs) and carbonyls were subject to chemical speciation. Globally, the supermarket presented CO2, VOCs, and PM10 values below the limits imposed by international regulations. The PM10 concentration in the supermarket was 33.5 ± 23.2 μg/m3, and the indoor-to-outdoor PM10 ratio was 1.76. Carbonaceous constituents represented PM10 mass fractions of 21.6% indoors and 15.3% outdoors. Due to the use of stainless-steel utensils, flour and fermentation processes, the bakery proved to be a pollution hotspot, presenting the highest concentrations of PM10 (73.1 ± 9.16 μg/m3), PM10-bound elements (S, Cl, K, Ca, Ti, and Cr) and acetaldehyde (42.7 μg/m3). The maximum tetrachloroethylene level (130 μg/m3) was obtained in the cleaning products section. The highest values of colony-forming units of bacteria and fungi were recorded in the bakery, and fruit and vegetable section. The most prevalent fungal species was Penicillium sp., corresponding to 56.9% of the total colonies. In addition, other fungal species/sections with toxicological or pathogenic potential were detected (Aspergillus sections Aspergilli, Circumdati, Flavi, Mucor and Fusarium sp.).

Filling the knowledge gap: Scoping review regarding sampling methods, assays, and further requirements to assess airborne viruses

Assessment of occupational exposure to viruses is crucial to identify virus reservoirs and sources of dissemination at an early stage and to help prevent spread between employees and to the general population. Measuring workers' exposure can facilitate assessment of the effectiveness of protective and mitigation measures in place. The aim of this scoping review is to give an overview of available methods and those already implemented for airborne virus' exposure assessment in different occupational and indoor environments. The results retrieved from the different studies may contribute to the setting of future standards and guidelines to ensure a reliable risk characterization in the occupational environments crucial for the implementation of effective control measures. The search aimed at selecting studies between January 1st 2010 and June 30th 2023 in the selected databases. Fifty papers on virus exposure assessment fitted the eligibility criteria and were selected for data extraction. Overall, this study identified gaps in knowledge regarding virus assessment and pinpointed the needs for further research. Several discrepancies were found (transport temperatures, elution steps, …), as well as a lack of publication of important data related to the exposure conditions (contextual information). With the available information, it is impossible to compare results between studies employing different methods, and even if the same methods are used, different conclusions/recommendations based on the expert judgment have been reported due to the lack of consensus in the contextual information retrieved and/or data interpretation. Future research on the field targeting sampling methods and in the laboratory regarding the assays to employ should be developed bearing in mind the different goals of the assessment.

Filling the Knowledge Gap Regarding Microbial Occupational Exposure Assessment in Waste Water Treatment Plants: A Scoping Review

BACKGROUND

Wastewater treatment plants (WWTPs) are crucial in the scope of European Commission circular economy implementation. However, bioaerosol production may be a hazard for occupational and public health. A scoping review regarding microbial contamination exposure assessment in WWTPs was performed.

METHODS

This study was performed through PRISMA methodology in PubMed, Scopus and Web of Science.

RESULTS

28 papers were selected for data extraction. The WWTPs' most common sampled sites are the aeration tank (42.86%), sludge dewatering basin (21.43%) and grit chamber. Air sampling is the preferred sampling technique and culture-based methods were the most frequently employed assays. Staphylococcus sp. (21.43%), Bacillus sp. (7.14%), Clostridium sp. (3.57%), Escherichia sp. (7.14%) and Legionella sp. (3.57%) were the most isolated bacteria and Aspergillus sp. (17.86%), Cladosporium sp. (10.71%) and Alternaria sp. (10.71%) dominated the fungal presence.

CONCLUSIONS

This study allowed the identification of the following needs: (a) common protocol from the field (sampling campaign) to the lab (assays to employ); (b) standardized contextual information to be retrieved allowing a proper risk control and management; (c) the selection of the most suitable microbial targets to serve as indicators of harmful microbial exposure. Filling these gaps with further studies will help to provide robust science to policy makers and stakeholders.

Portuguese cork industry: filling the knowledge gap regarding occupational exposure to fungi and related health effects

Introduction

The presence of the Penicillium section Aspergilloides (formerly known as Penicillium glabrum) in the cork industry involves the risk of respiratory diseases such as suberosis.

Methods

The aim of this study was to corroborate the predominant fungi present in this occupational environment by performing a mycological analysis of 360 workers' nasal exudates collected by nasal swabs. Additionally, evaluation of respiratory disorders among the cork workers was also performed by spirometry.

Results

Penicillium section Aspergilloides was detected by qPCR in 37 out of the 360 nasal swabs collected from workers' samples. From those, 25 remained negative for Penicillium sp. when using culture-based methods. A significant association was found between ventilatory defects and years of work in the cork industry, with those people working for 10 or more years in this industry having an approximately two-fold increased risk of having ventilatory defects compared to those working less time in this setting. Among the workers who detected the presence of Penicillium section Aspergilloides, those with symptoms presented slightly higher average values of CFU.

Discussion

Overall, the results obtained in this study show that working in the cork industry may have adverse effects on worker's respiratory health. Nevertheless, more studies are needed (e.g., using serological assays) to clarify the impact of each risk factor (fungi and dust) on disease etiology.

Assessment of Portuguese fitness centers: Bridging the knowledge gap on harmful microbial contamination with focus on fungi

The lack of knowledge regarding the extent of microbial contamination in Portuguese fitness centers (FC) puts attendees and athletes at risk for bioaerosol exposure. This study intends to characterize microbial contamination in Portuguese FC by passive sampling methods: electrostatic dust collectors (EDC) (N = 39), settled dust (N = 8), vacuum filters (N = 8), and used cleaning mops (N = 12). The obtained extracts were plated in selective culture media for fungi and bacteria. Filters, EDC, and mop samples' extracts were also screened for antifungal resistance and used for the molecular detection of the selected Aspergillus sections. The detection of mycotoxins was conducted using a high-performance liquid chromatograph (HPLC) system and to determine the cytotoxicity of microbial contaminants recovered by passive sampling, HepG2 (human liver carcinoma) and A549 (human alveolar epithelial) cells were employed. The results reinforce the use of passive sampling methods to identify the most critical areas and identify environmental factors that influence microbial contamination, namely having a swimming pool. The cardio fitness area presented the highest median value of total bacteria (TSA: 9.69 × 102 CFU m-2.day-1) and Gram-negative bacteria (VRBA: 1.23 CFU m-2.day-1), while for fungi it was the open space area, with 1.86 × 101 CFU m-2.day-1. Aspergillus sp. was present in EDC and in filters used to collect settled dust. Reduced azole susceptibility was observed in filters and EDC (on ICZ and VCZ), and in mops (on ICZ). Fumonisin B2 was the only mycotoxin detected and it was present in all sampling matrixes except settled dust. High and moderate cytotoxicity was obtained, suggesting that A549 cells were more sensitive to samples' contaminants. The observed widespread of critical toxigenic fungal species with clinical relevance, such as Aspergillus section Fumigati, as well as Fumonisin B2 emphasizes the importance of frequent and effective cleaning procedures while using shared mops appeared as a vehicle of cross-contamination.

Assessment of waste workers occupational risk to microbial agents and cytotoxic effects of mixed contaminants present in the air of waste truck cabin and ventilation filters

Workers in the waste-processing industry are potentially exposed to high concentrations of biological contaminants, leading to respiratory and digestive problems and skin irritations. However, few data on the exposure of waste collection truck (WCT) drivers are available. The goal was to document the microbial risk of the waste collection truck (WCT) workers while in the vehicle cab. Long-period sampling using the truck air filters (CAF) and short time ambient air sampling in the cab were used. The potential release of microbial particles from CAFs was also investigated since it could contribute to the microbial load of the cabin air. A combination of analytical methods also helped assess the complex mixture of the biological agents. Aspergillus sections Fumigati and Flavi, E. coli, Enterobacter spp. and Legionella spp. were detected in the CAF of trucks collecting three types of waste. The highest levels of bacteria and fungi were found in the CAF from organic WCT. The highest endotoxin concentrations in CAF were 300 EU/cm2. Most of the CAF showed cytotoxic effects on both lung cells and hepatocytes. Only one mycotoxin was detected in a CAF. The maximal concentrations in the ambient WCT air varied according to the type of waste collected. The highest proportion (84%) of the air samples without cytotoxic effects on the lungs cells was for the recyclable material WCTs. The results revealed the potential microbial risk to workers from a complex mixture of bio-contaminants in the cabs of vehicles collecting all types of waste. The sustained cytotoxic effect indicates the potential adverse health-related impact of mixed contaminants (biological and non-biological) for the workers. Overall, this study highlights the benefits of using complementary sampling strategy and combined analytical methods for a the assessment of the microbial risk in work environments and the need to implement protective measures for the workers.Implications: Exposure to microbial agents is a well-known occupational hazard in the waste management sector. No previous study had evaluated the cytotoxicity of ambient air and ventilation filters to document worker exposure to a combination of contaminants during waste collection. This research confirms the usefulness of ventilation filters for long-term characterization of exposure to infectious agents, azole-resistant fungi, coliform bacteria and mycotoxin. Overall, this study highlights the importance of using several sampling and analysis methods for a comprehensive assessment of microbial risk in work environments, as well as the need to implement appropriate protective measures for collection workers.

Comprehensive assessment of occupational exposure to microbial contamination in waste sorting facilities from Norway

Introduction

It is of upmost importance to contribute to fill the knowledge gap concerning the characterization of the occupational exposure to microbial agents in the waste sorting setting (automated and manual sorting).

Methods

This study intends to apply a comprehensive field sampling and laboratory protocol (culture based-methods and molecular tools), assess fungal azole resistance, as well as to elucidate on potential exposure related health effects (cytotoxicity analyses). Skin-biota samples (eSwabs) were performed on workers and controls to identify other exposure routes.

Results

In personal filter samples the guidelines in one automated industry surpassed the guidelines for fungi. Seasonal influence on viable microbial contamination including fungi with reduced susceptibility to the tested azoles was observed, besides the observed reduced susceptibility of pathogens of critical priority (Mucorales and Fusarium sp.). Aspergillus sections with potential toxigenic effect and with clinical relevance were also detected in all the sampling methods.

Discussion

The results regarding skin-biota in both controls´ and workers´ hands claim attention for the possible exposure due to hand to face/mouth contact. This study allowed concluding that working in automated and manual waste sorting plants imply high exposure to microbial agents.

Distribution characteristics and potential risks of bacterial aerosol in waste transfer station

The waste transfer station (WTS) is an important link in the transfer of municipal solid waste (MSW) between the community and disposal terminals. While WTSs facilitate waste collection in communities, odorous gases and bioaerosols can escape from them, thereby negatively affecting their surroundings. In this study, the concentration, particle size distribution, pathogen population, and health risks of bioaerosols were analyzed at different locations in a transfer station. The results showed that the highest viable bacterial aerosol concentration was 10,353 ± 3701 CFU/m³, which was at 5 m from the disposal site. Fifty-three bacterial species, including pathogens, were detected. Of these, 39 were human pathogenic bacteria directly originating from the WTS. Furthermore, health risk assessments indicated unacceptable levels of non-carcinogenic risk for operational workers caused by bacterial aerosols of the WTS work area. In addition, bacterial aerosols may pose a severe health risk to children within a 15 m area of the WTS. The results of this study provide a scientific basis to control and reduce the risk associated with bioaerosol exposure in solid WTSs.

Microbial Contamination in the Coffee Industry: An Occupational Menace besides a Food Safety Concern?

Respiratory abnormalities among workers at coffee roasting and packaging facilities have already been reported; however, little is known about microbiological contamination inside coffee production facilities. This study intends to assess the microbial contamination (fungi and bacteria) in two coffee industries from Brazil with a multi-approach protocol for sampling and for subsequent analyses using four main sources of samples: filtering respiratory protection devices (FRPD) used by workers, settled dust, electrostatic dust cloths (EDC) and coffee beans. The fungal contamination in the assessed industries was also characterized through the molecular detection of toxigenic species and antifungal resistance. Total bacteria contamination presented the highest values in FRPD collected from both industries (7.45 × 104 CFU·m-2; 1.09 × 104 CFU·m-2). Aspergillus genera was widespread in all the environmental samples collected and sections with clinical relevance (Fumigati) and with toxigenic potential (Nigri and Circumdati) were recovered from FRPD. Circumdati section was observed in 4 mg/mL itraconazole. Sections Circumdati (EDC, coffee beans and settled dust) and Nidulantes (EDC, coffee beans and FRPD) were detected by qPCR. Some of the targeted Aspergillus sections that have been identified microscopically were not detected by qPCR and vice-versa. Overall, this study revealed that microbial contamination is a potential occupational risk in the milling stage and should be tackled when assessing exposure and performing risk assessment. In addition, a multi-sampling campaign should be the approach to follow when assessing microbial contamination and FRPD should be included in this campaign. Occupational exposure to mycotoxins should be considered due to high fungal diversity and contamination. A One Health approach should address these issues in order to prevent consumption of coffee crops and beans infected by fungi and, more specifically, to avoid widespread azole resistance.

Unveiling the Occupational Exposure to Microbial Contamination in Conservation–Restoration Settings

Assuring a proper environment for the fulfillment of professional activities is one of the Sustainable Development Goals and is contemplated in the One Health approach assumed by the World Health Organization. This particular study is applied to an often neglected sector of our society—the conservators/restorers—despite the many health issues reported by these professionals. Three different specialties (textiles, paintings and wood sculpture) and locations were selected for evaluation by placement of electrostatic dust cloths. After treatment of the samples, bacterial and fungal contamination were assessed, as well as mycotoxin determination, the presence of azole-resistant strains and cytotoxicity of the microorganisms encountered. Bacteria were only present in one of medias used and showed relatively low numbers. The highest level of contamination by fungi was identified in one of the textiles settings. The textile area also showed the highest variability for fungi. Aspergillus sp. are one indicator of possible environmental issues, and A. sections Fumigati and Circumdati were particularly relevant in two of the settings and identified in all of them. No mycotoxins were detected and the large majority of the fungi identified were non-cytotoxic. Overall, these can be considered low-contaminated environments but attention should be given to the Aspergillus sp. contamination. Additional studies are needed not only to make these results more robust, but also to test if the environmental sampling alone is the best approach in a setting where there is very little movement and dust displacement and where professionals are in very close proximity to the artefacts being treated, which may suggest the existence of a micro-atmosphere worth evaluating and comparing to the obtained results.