A cohort study of wastewater treatment plant workers: Association between levels of biomarkers of systemic inflammation and exposure to bacteria and fungi, and endotoxin as measured using two methods

Intestinal bacteria aerosols from hospital and municipal wastewater treatment: Seasonal variations, dispersal characteristics and toxic effects

Wastewater contains a rich abundance of intestinal pathogens, which can be released into the air during the wastewater treatment process, posing hazards to occupational workers and surrounding residents. Hospital wastewater contains a higher concentration of pathogens compared to urban wastewater, potentially causing greater harm to human health. In this study, a one-year collection of bioaerosols was conducted at a hospital sewage station (HSS) and a municipal sewage plant (MSP) to investigate the characteristics of intestinal bacteria in bioaerosols from different wastewater sources. The concentration of intestinal bacteria in the biological tank air at HSS ranged from 16 to 42 CFU/m3, while at MSP, the concentration range was from 19 to 30 CFU/m3. The airborne bacterial concentration was highest during the summer season. The average proportions of fine particles (<2.5 μm) in the air of HSS and MSP were 45.48% and 41.59%, respectively. The predominant intestinal bacteria detected in HSS bioaerosols were uncultured_bacterium_f_Enterobacteriaceae, Pantoea, and Serratia. The primary intestinal bacteria in MSP bioaerosols were Brevundimonas, Pseudomonas, and Enterobacteriaceae. Bioaerosols can rapidly diffuse into the surrounding environment. After 1 h of diffusion, the average diffusion areas of bioaerosols from HSS and MSP were 131.79 km2 and 159.01 km2, respectively. Exposure to bioaerosols generated from hospital wastewater can cause damage to the respiratory system of mice. The biological components in the bioaerosols can lead to significant increases in the expression levels of IL-6 and TNF-α in the serum of mice, as well as marked pathological changes in the lungs. This study reveals the potential health hazards of inhaling bioaerosols generated from wastewater and provides a scientific basis for formulating management measures for bioaerosols.

Characterization of bioaerosol exposures in wastewater treatment plant workers and serum levels of lung and inflammatory markers

Wastewater treatment plant (WWTP) workers are exposed to bioaerosols containing bacteria, fungi, and endotoxin, potentially posing health risks to workers. This study quantified personal exposure levels to airborne bacteria and fungi, endotoxin, and dust among 44 workers during two seasons at four WWTPs. Associations between the exposure measurements and serum levels of biomarkers CRP, SAA, and CC16 were also assessed. The potential deposition of viable microorganisms in workers' airways were explored using stationary fractionating samplers. Microbial communities were characterized using long-read nanopore amplicon sequencing and MALDI-TOF mass spectrometry to identify species, including pathogenic or allergenic microorganisms. We found that bacterial and fungal exposure levels were significantly associated with work task (p < 0.001 and p = 0.00041, respectively), with high exposure variability within and between tasks. Workshop, sewer system inspection, and sewer cleaning were associated with the highest exposure levels. A significant positive correlation was found between CRP and bacterial exposure (p = 0.013), while significant negative correlations were found between CRP and endotoxin and dust exposures (p = 0.012 and p = 0.018, respectively). No significant associations were found between SAA or CC16 and the exposure measures. Microbial community composition in bioaerosols differed significantly between some work tasks while others showed similar compositions. Viable hazardous microorganisms such as Clostridium perfringens and Aspergillus fumigatus were found in workers' exposures and in respiratory fractions of stationary air samples, indicating potential lung deposition. Further research is needed to assess possible long-term health risks from bioaerosol exposure at WWTPs.

C-reactive protein expression in acute ischemic stroke blood clots: Implications for etiology

INTRODUCTION

C-reactive protein (CRP) is a prototypic inflammation marker, with elevated levels associated with an increased risk of cerebrovascular events. To determine whether CRP could be a useful biomarker of stroke etiology, we investigated CRP expression in acute ischemic stroke (AIS) clots from large-artery atherosclerosis (LAA), cardio-embolism (CE) and cryptogenic (Crypt) subtypes.

PATIENTS AND METHODS

We analysed clot samples from AIS patients (LAA, CE, Crypt; n = 50 each), collected across five stroke centres in France, Serbia, Spain, and Japan between February 2021 and February 2024, as part of the prospective Clotbase International Registry of 460 patients who underwent mechanical thrombectomy. Clot components were assessed using Martius Scarlet Blue staining. CRP expression was examined using immunohistochemistry and its co-localisation with clot components was detected using immunofluorescence. Clinical parameters were compared across etiologies.

RESULTS

CRP expression varied significantly among clots. Most clots (65%) had minimal (⩽1%) CRP and 35% showed substantial (>1%) CRP. CE group had significantly more clots with substantial CRP than LAA and Crypt (48% vs 30% and 26%; p = 0.048). Clots with substantial CRP contained more fibrin (28.9%) than those with low CRP (20.6%; p = 0.005). Confocal microscopy showed CRP co-localised with fibrin and white blood cells (WBCs).

DISCUSSION AND CONCLUSION

Significantly more AIS clots of CE expressed substantial CRP compared to those of LAA and Crypt, suggesting CE strokes may be more strongly linked to inflammation. Clots with substantial CRP expression displayed significantly more fibrin compared to those with minimal CRP expression, suggesting a potential association between inflammation and fibrin-rich clots. Further study of the relationship between CRP, fibrin and WBCs in clots may improve our understanding of the processes of thrombo-inflammation.

Effects of Interventions to Prevent Work-Related Asthma, Allergy, and Other Hypersensitivity Reactions in Norwegian Salmon Industry Workers (SHInE): Protocol for a Pragmatic Allocated Intervention Trial and Related Substudies

BACKGROUND

Workers in the salmon processing industry have an increased risk of developing respiratory diseases and other hypersensitivity responses due to occupational exposure to bioaerosols containing fish proteins and microorganisms, and related allergens. Little is known about effective measures to reduce bioaerosol exposure and about the extent of skin complaints among workers. In addition, while identification of risk factors is a core activity in disease prevention strategies, there is increasing interest in health-promoting factors, which is an understudied area in the salmon processing industry.

OBJECTIVE

The overall aim of this ongoing study is to generate knowledge that can be used in tailored prevention of development or chronification of respiratory diseases, skin reactions, protein contact dermatitis, and allergy among salmon processing workers. The main objective is to identify effective methods to reduce bioaerosol exposure. Further objectives are to identify and characterize clinically relevant exposure agents, identify determinants of exposure, measure prevalence of work-related symptoms and disease, and identify health-promoting factors of the psychosocial work environment.

METHODS

Data are collected during field studies in 9 salmon processing plants along the Norwegian coastline. Data collection comprises exposure measurements, health examinations, and questionnaires. A wide range of laboratory analyses will be used for further analysis and characterization of exposure agents. Suitable statistical analysis will be applied to the various outcomes of this comprehensive study.

RESULTS

Data collection started in September 2021 and was anticipated to be completed by March 2023, but was delayed due to the COVID-19 pandemic. Baseline data from all 9 plants included 673 participants for the health examinations and a total of 869 personal exposure measurements. A total of 740 workers answered the study's main questionnaire on demographics, job characteristics, lifestyle, health, and health-promoting factors. Follow-up data collection is not completed yet.

CONCLUSIONS

This study will contribute to filling knowledge gaps concerning salmon workers' work environment. This includes effective workplace measures for bioaerosol exposure reduction, increased knowledge on hypersensitivity, allergy, respiratory and dermal health, as well as health-promoting workplace factors. Together this will give a basis for improving the work environment, preventing occupational health-related diseases, and developing occupational exposure limits, which in turn will benefit employees, employers, occupational health services, researchers, clinicians, decision makers, and other stakeholders.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05039229; https://www.clinicaltrials.gov/study/NCT05039229.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/48790.

Health symptoms, inflammation, and bioaerosol exposure in workers at biowaste pretreatment plants

Biowaste pretreatment plants have been built within the last years in Denmark in order to recycle pre-sorted biowaste from houses, restaurants, and industry. We investigated the association between exposure and health at six biowaste pretreatment plants (visited twice) across Denmark. We measured the personal bioaerosol exposure, took blood samples, and administered a questionnaire. Thirty-one persons participated, 17 of them twice, resulting in 45 bioaerosol samples, 40 blood samples, and questionnaire answers from 21 persons. We measured exposure to bacteria, fungi, dust, and endotoxin, the total inflammatory potential of the exposures, and serum levels of the inflammatory markers serum amyloid A (SAA), high sensitivity C-reactive protein (hsCRP), and human club cell protein (CC16). Higher exposures to fungi and endotoxin were found for workers with tasks inside the production area compared to workers with main tasks in the office area. A positive association was found between the concentration of anaerobic bacteria and hsCRP and SAA, whereas bacteria and endotoxin were inversely associated with hsCRP and SAA. A positive association between hsCRP and the fungal species Penicillium digitatum and P. camemberti were found, whereas an inverse association between hsCRP and Aspergillus niger and P. italicum were found. Staff with tasks inside the production area reported more symptoms of the nose than those working in the office area. To conclude, our results indicate that workers with tasks inside the production area are exposed to elevated levels of bioaerosols, and that this may affect workers' health negatively.