1,721,013 research outputs found
The use of Quantitative Microbial Risk Assessment for the airborne biological risk assessment in occupational settings
Full text linkQMRA (QuantitativeMicrobial risk assessment): un approccio innovativo per la valutazione e la gestione del rischio biologico occupazionale
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Quantitative Microbial Risk Assessment for Bathers in a Popular Bathing Area in Northern Italy
No full textIn this study, we used QMRA based on enterococci counts in order to evaluate the Gastrointestinal Illnesses (GI) risk resulting from
recreational activities at a very popular seaside resort in Italy. Three bathing areas were selected, since they are impacted by riverine
discharges, that receive polluted waters from point and non-point sources, and have been sometimes closed, owing to enterococci and E.coli levels over the European regulation. The swimmer GI risk from enterococci was estimated applying exponential dose-response model, and the simulation for QMRA model were performed using Vensim software. The ingested enterococci dose was calculated combining ingestion rate, exposure time and enterococci concentrations. In particular, exposure time was fitted to a Weibull distribution and the ingestion rate was drawn from a triangular distribution. Enterococci concentrations were fitted to a lognormal distribution for each monitoring area, basing on 10-years microbial data collected from seawaters at the river mouths. The risk estimation was obtained through the use of a Monte Carlo simulation, with each run consisting of 10 000 trials. The results were compared to acceptable marine recreational illness levels of 10 and 50 GI illnesses per 1 000 exposures (0.01 and 0.05). The results showed a difference in GI risk among the three bathing areas, with a probability of exceeding the illness acceptable levels of 0.6% and 0.01 % (respectively) for No1 area, 0.63% and 0% for No2 area and 1.34% and 0.07% for No3 area. Based on monitoring data collected according to European Bathing Directive, the percentage of values over the limits for beach closures were 3.5% for No1 area, 2.7% for No2 area and 4.9% for No3 area. These results should be further evaluated to better understand why the punctual
monitoring based on current legislation seems to overestimate the risk of GI compared to QMRA model outcomes
Valutazione quantitativa del rischio biologico (QMRA) da bioaerosol in vari ambienti lavorativi
No full textIntroduzione: La valutazione e la gestione del rischio di esposizione
lavorativa a bioaerosol risultano in genere difficili. Il processo QMRA (Quantitative Microbial Risk Assessment), già applicato
a livello internazionale nella sicurezza alimentare e delle acque, potrebbe rivelarsi uno strumento efficace per la tutela della
salute dei lavoratori. Obiettivo di questo studio è stato quello di elaborare ed applicare un modello QMRA all’esposizione
a patogeni aerodispersi in diversi ambienti di lavoro. Metodi: Poiché l’applicazione del modello richiede dati di infettività
e patogenicità è stato scelto HAdV (Human Adenovirus) come patogeno indice, giudicato rappresentativo di vari contesti
e modalità di infezione: molto diffuso, facilmente reperibile con metodi colturali e biomolecolari e patogeno a livello sia
respiratorio che enterico, con dosi infettanti note. Nel modello sono state utilizzate le concentrazioni di HAdV (in CG/m3)
trovate nell’aria di impianti di trattamento di reflui e di rifiuti solidi urbani ed in ambienti ospedalieri, misurate attraverso la
q-PCR, mentre gli altri parametri necessari sono stati ricavati dalla letteratura scientifica. Risultati: Il monitoraggio virologico
ha evidenziato la presenza di HAdV in tutti gli ambienti considerati confermando la loro ampia diffusione. Le concentrazioni
sono risultate tuttavia differenti. Il modello ha mostrato che per gli ambienti a maggiore contaminazione l’esposizione per
periodi superiori a 3 minuti porterebbe ad una probabilità di infezione del 100% mentre negli ambienti meno contaminati
anche dopo 15 minuti la probabilità rimane al di sotto dell’1%. Conclusioni: Questo strumento potrebbe essere utile per
stabilire la necessità di adottare DPI respiratori. Tuttavia, poiché rappresenta un approccio innovativo, il modello dovrà essere
implementato e validato su ulteriori dati
Quantitative Microbial Risk Assessment (QMRA): metodo innovativo per stimare il rischio biologico occupazionale
No full textINTRODUZIONE
La valutazione del rischio biologico occupazionale da esposizione a bioaerosol contaminato si basa usualmente sul monitoraggio di indicatori generici di contaminazione e fornisce una classificazione approssimativa in livelli di rischio, senza considerare patogeni eventualmente presenti e relazioni dose-risposta. Lo sviluppo delle conoscenze microbiologiche ed epidemiologiche consente oggi di applicare un metodo di stima del rischio, basato sul paradigma del rischio chimico, che prende il nome di QMRA. Questo lavoro ha applicato tale metodo in diversi contesti e condizioni.
METODI
E’ stato scelto come patogeno indice l’Adenovirus umano (HAdV) per la sua grande diffusione. Per descrivere la probabilità di infezione è stato implementato un modello dinamico che usa una relazione dose-risposta di tipo esponenziale (ricavata dalla letteratura) per l’HAdV, ed ha come dati di ingresso i valori delle concentrazioni di HAdV nell’aria. L’applicazione del metodo Monte Carlo ha consentito di rappresentare la variabilità e l’incertezza delle distribuzioni di probabilità delle variabili coinvolte. Il modello è stato applicato ai dati ottenuti da vari studi che hanno monitorato la concentrazione di Human Adenovirus (HAdV) in diversi ambienti occupazionali: i) discariche RSU, ii) impianti di depurazione di acque reflue, iii) bagni ospedalieri e iv) bagni di uffici.
RISULTATI
L’applicazione del modello ha consentito di simulare la probabilità di infezione in diversi ambienti lavorativi e per diversi tempi di esposizione evidenziando ad esempio un maggior rischio in ambienti confinati rispetto a quelli esterni (Figura 1).
CONCLUSIONI
Applicando la QMRA con il metodo Monte Carlo è stato possibile stimare il rischio di infezione per i lavoratori esposti ad aerosol per determinati periodi di tempo. E’ necessario tuttavia sottolineare che il modello attuale non tiene conto dell’immunità dei soggetti esposti. Questo parametro potrà essere inserito negli sviluppi futuri
Quantitative microbial risk assessment in occupational settings: the airborne infectious biological risk
No full textThe assessment of occupational biological risk is generally limited to the evaluation of a "potential exposure", without any quantitative estimate. The risk assessment output is then usually expressed as a level (low, medium, high) and represented in risk matrices combining magnitude and probability scores. A possible innovative approach for the risk assessment in occupational settings characterized by bioaerosol exposure is to monitor the air for a pathogen that can be further used for QMRA. Adenovirus is the virus that contains the highest amount of features favorable to its use as a virological indicator. This pathogenic virus has a low infectious dose, it is resistant on the environment, abundant, easily detected by molecular methods and is of great importance in public health. In this study, HAdV is used as the reference pathogen to develop a preliminary QMRA model to assess the microbial risk associated with the inhalation of contaminated bioaerosols. This model was then applied to data on air contamination from different settings (wastewater treatment plants, solid waste landfills, toilets in offices and hospitals) and with various exposure times. Air samples (1000 l of air in the indoor workplace and 3000 l of outdoor) were collected using an impactor sampler and the genomic concentration of positive samples was measured by real-time polymerase chain reaction (q-PCR). The virological monitoring showed the presence of HAdVs in all the considered settings, thus confirming their wide diffusion, nevertheless, the average concentrations of HAdV were different. The model estimates show that in the most contaminated settings a stay longer than 3 minutes would lead to a probability of infection of 100%, while for the less contaminated areas even after 15 min the probability of infection remains around 1%. The definition of critical exposure times, using a QMRA model, could be useful to give operational guidance for risk management on the use of respiratory personal protection equipment (RPPE). This approach is new and should be faced with caution. However it is worthy of discussion and further investigation
The application of quantitative microbial risk assessment to natural recreational waters: A review
No full textThis review examines the aims of and approaches to the Quantitative Microbial Risk Assessment (QMRA) of untreated recreational waters. The literature search was conducted on four databases and yielded 54 papers, which were analyzed on a quantitative (time-trend, geographical distribution, water type) and qualitative (aims, source of microbial data, pathogens and their measurement or estimation, ways to address variability and uncertainty, sensitivity analysis) basis. In addition, the parameters, implications, and limitations were discussed for each QMRA step. Since 2003, the number of papers has greatly increased, highlighting the importance of QMRA for the risk management of recreational waters. Nevertheless, QMRA still exhibits critical issues, above all regarding contamination data and dose-response relationships. To our knowledge, this is the first review to give a wide panoramic view on QMRA in relation to recreational exposure to untreated waters. This could be useful in identifying the current knowledge gaps and research needs
La presenza di human adenovirus nelle acque e il suo possibile ruolo di indicatore di qualità virologica
No full textQuantitative Microbial Risk Assessment in Occupational Settings Applied to the Airborne Human Adenovirus Infection
Full text linkQuantitative Microbial Risk Assessment (QMRA) methodology, which has already been applied to drinking water and food safety, may also be applied to risk assessment and management at the workplace. The present study developed a preliminary QMRA model to assess microbial risk that is associated with inhaling bioaerosols that are contaminated with human adenovirus (HAdV). This model has been applied to air contamination data from different occupational settings, including wastewater systems, solid waste landfills, and toilets in healthcare settings and offices, with different exposure times. Virological monitoring showed the presence of HAdVs in all the evaluated settings, thus confirming that HAdV is widespread, but with different average concentrations of the virus. The QMRA results, based on these concentrations, showed that toilets had the highest probability of viral infection, followed by wastewater treatment plants and municipal solid waste landfills. Our QMRA approach in occupational settings is novel, and certain caveats should be considered. Nonetheless, we believe it is worthy of further discussions and investigations
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