Suchergebnisse

Abstract
To protect the general population as well as workers, authorities have to identify the most toxic compounds in the particulate aerosol and effectively reduce their concentrations. As the oxidative potential (OP) is suggested to be linked with health effects, it may be more effective to control specific sources of oxidizing particles rather than overall particulate mass. In that case, the use of direct-reading instruments for OP measurement could help to the effective control of noxious air pollutant sources. We present here the development and characterization of a direct-reading instrument based on the acellular ferrous-orange xylenol (FOX) assay, allowing a continuous sensing of ambient oxidizing compounds. The detection principle relies on multiscattering-enhanced absorbance strategy enabling sensitive detection of airborne oxidants (e.g. hydrogen peroxide, hydroxyl radical) with a time resolution of 5 min. Two parallel tasks to improve the reading instrument are underway: 1. A better understanding of the FOX response to the potentially interfering ozone and NOx gases and it relationship with emission sources; 2. Improving the interface for transferring the aerosol in the FOX solution and characterizing the instrument regarding it sensibility, linearity, repeatability and response time. Continuous determination of OP will enable robust epidemiological studies to evidence potential associations with oxidative stress-related and inflammatory disorders. In the future, mapping the average annual OP – together with current PM10, NOx and O3 – will be an essential chemical dimension of the pollution profile.

Abstract
Hydrogen peroxide (H2O2) is a strong oxidizing agent often used in hair coloring and as a component in disinfecting and bleaching processes. Exposures to H2O2 generate reactive oxygen species (ROS) that can cause significant airway irritation and inflammation. Even though workers have reported symptoms associated with sensitivity and irritation from acute exposures below the H2O2 occupational exposure levels (OELs), a lack of sensitive analytical methods for measuring airborne concentrations currently prevents evaluating low or peak H2O2 exposures. To fill these gaps, we propose two different sensitive approaches: (i) luminol chemiluminescence (CL) to specifically measure H2O2; and (ii) photonic sensor method based on the ferrous-xylenol orange assay to evaluate total oxidative potential (OP), a measure of ROS in sampled air. We chose two exposure scenarios: hairdressers preparing and applying hair color to clients (both in simulated and field environments) and workers operating disinfecting cycles at a bottling company. Hair coloring took about 1 h for each client, and the application of the coloring product generated the highest H2O2 concentrations. OP values were highly correlated with H2O2 concentrations (CL measurement) and allowed peak measurements as low as 6 µg m-3 of H2O2 concentrations. The bottling company used a disinfectant containing H2O2, acetic acid and peracetic acid (PAA) in an enclosed process. The photonic sensor was immediately saturated. The CL results showed that the process operator had the highest exposures during a 15-min cycle. There is still a need to develop these direct reading methods for operating in the field, but we believe that in the future an OEL for OP could protect workers from developing airway irritation and inflammation by reducing exposures to oxidizing chemicals.

Abstract
We aimed at analyzing dose-response relationship between occupational exposure to a mixture of nanomaterials (NMs) and effect biomarkers measured according to the NanoExplore protocol in exhaled breath condensate (EBC, local pulmonary level)) and urine (systemic level) of 141 workers. Two exposure metrics: particle number concentration (PNC) and lung deposited surface area (LDSA) were monitored using DiSCMini for 2-4 8h-workshifts. Biological samples were collected twice, before and after exposure monitoring. We assumed that current or short-term exposure to NMs is associated in a linear dose-response manner to the effect biomarker concentration. We analyzed each biomarker separately, using the multilevel mixed-effects interval regression models to properly manage the biomarker concentrations the LOD or in the interval between the LOD and the limit of quantification. We used directed acyclic graphs to identify all potential confounders: age, smoking status, medication status, and study center. Center and the participant's ID were modeled as random effect variables. For IL-10, IL-1β and TNF-α in EBC we observed consistent positive dose-response relationships with both PNC and LDSA. For urinary Total Antioxidant Power the relationship was consistently negative. For MDA, KL-6, hs-CRP or NOTyr in EBC and urinary MDA and 8-Isoprostane, no relationship was found. These results suggest an activation of the innate immune response rather than oxidative stress as the main effect of the mixture of NM investigated. This study offers new insights into the dose-response relationship between exposure to NMs and possible indicators of early and long-term biological alterations in the cohort of recruited workers.