Oxidative potential of aerosolized metalworking fluids in occupational settings.

The oxidative potential (OP) measures the ability of pollutants to oxidize a chemical/biological probe. Such assays are starting to gain acceptance as integrative exposure metrics associated with inflammatory-based pathologies. Diseases such as asthma, rhinitis or cancers are reported for workers exposed to oil mist, which are aerosols of metal working fluids (MWF) emitted during the machining of metals. Measuring oil mist in the air is challenging, and exposures are often quantified as the mass fraction, which does not account for exposures to the gaseous fraction. Consequently, exposures are underestimated and furthermore, the hazardous property of oil mist is not assessed. We postulate that it is more relevant to assess occupational exposures to the hazardous fractions of oil mist by measuring OP than by simply measuring mass. We characterized exposures to straight and water-based MWF among workers in the French and Swiss mechanical industry using standard methods for oil mist and the ferrous orange xylenol assay for OP assessment (OPFOX). Considering the particulate fraction, the water-based MWF presented the greatest OPFOX. The OP was associated with organic carbon and iron content. The gaseous fraction of the oil mist presented also an important redox activity, particularly in workshops where straight oils were used. The hexanal concentration was associated with this OPFOX. The OPFOX measurement is thus integrative of multiple parameters, and bring complementary information when assessing MWF exposures. Our results highlight that OPFOX account for MWF type and could be an interesting parameter to characterize such exposure.

Reusability of filtering facepiece respirators after decontamination through drying and germicidal UV irradiation.

INTRODUCTION: During pandemics, such as the SARS-CoV-2, filtering facepiece respirators plays an essential role in protecting healthcare personnel. The recycling of respirators is possible in case of critical shortage, but it raises the question of the effectiveness of decontamination as well as the performance of the reused respirators. METHOD: Disposable respirators were subjected to ultraviolet germicidal irradiation (UVGI) treatment at single or successive doses of 60 mJ/cm2 after a short drying cycle (30 min, 70°C). The germicidal efficacy of this treatment was tested by spiking respirators with two staphylococcal bacteriophages (vB_HSa_2002 and P66 phages). The respirator performance was investigated by the following parameters: particle penetration (NaCl aerosol, 10-300 nm), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry and mechanical tensile tests. RESULTS: No viable phage particles were recovered from any of the respirators after decontamination (log reduction in virus titre >3), and no reduction in chemical or physical properties (SEM, particle penetrations <5%-6%) were observed. Increasing the UVGI dose 10-fold led to chemical alterations of the respirator filtration media (FTIR) but did not affect the physical properties (particle penetration), which was unaltered even at 3000 mJ/cm2 (50 cycles). When respirators had been used by healthcare workers and undergone decontamination, they had particle penetration significantly greater than never donned respirators. CONCLUSION: This decontamination procedure is an attractive method for respirators in case of shortages during a SARS pandemic. A successful implementation requires a careful design and particle penetration performance control tests over the successive reuse cycles.

From nano to micrometer size particles - A characterization of airborne cement particles during construction activities.

Although, photocatalytic cement contains nanosized TiO2, a possibly carcinogen, no exposure assessments exist for construction workers. We characterized airborne nanoparticle exposures during construction activities simulated in an exposure chamber. We collected some construction site samples for regular cement in Switzerland and Thailand for comparison. Airborne nanoparticles were characterized using scanning mobility particle sizer (SMPS), portable aerosol spectrometer (PAS), diffusion size classifier (DiSCmini), transmission electron microscopy (TEM), scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDX), and X-ray diffraction. Bagged photocatalytic cement had 2.0 wt% (GSD ± 0.55) TiO2, while TiO2 in aerosols reached 16.5 wt% (GSD ± 1.72) during bag emptying and 9.7 wt% (GSD ± 1.36) after sweeping. The airborne photocatalytic cement particles were far smaller (approximately 50 nm) compared to regular cement. Cutting blocks made from photocatalytic cement or concrete, resulted in similar amounts of airborne nano TiO2 (2.0 wt% GSD ± 0.57) particles as in bagged material. Both photocatalytic and regular cement had a geometric mean diameter (GMD) < 3.5 µm. Main exposures for Thai workers were during sweeping and Swiss workers during drilling and polishing cement blocks. Targeted nanoparticle exposure assessments are needed as a significantly greater exposure to nano TiO2 were observed than what would have been predicted from the material's nano- TiO2 contents.

Differences among Thai Agricultural Workers' Health, Working Conditions, and Pesticide Use by Farm Type.

More than 11 million Thai people (38%) work in agriculture, but since most are in the informal sector, government enforcement and support are very limited. As a result, working conditions on Thai farms vary greatly, putting the health of many agricultural workers at risk. A cross-sectional study in three Thai provinces collected information on the work activities and conditions of 424 farmers representing five farm types: rice, vegetable, flower, rice/vegetable, and flower/vegetable. The agricultural workers were mainly women (60%); their average age was 53 but ranged from 18 to 87 years. More than 64% worked more than 5 days/week. Seventy-four percent of them had only primary school education. A number of the health and hazardous working conditions surveyed were significantly different by farm type. Rice farmers were found to have the highest prevalence of allergies, nasal congestion, wheezing, and acute symptoms after pesticide use, while flower farmers had the lowest prevalence of these health outcomes. Rice farmers reported the highest prevalence of hazardous working conditions including high noise levels, working on slippery surfaces, sitting or standing on a vibrating machine, spills of chemicals/pesticides, and sharp injuries. The lowest prevalence of these working conditions (except noise) was reported by flower farmers. Vegetable farmers reported the highest prevalence knee problems, while rice farmers had the lowest prevalence. Among these farmers, more than 27 different types of pesticides were reported in use during the past year, with the majority reporting use once a month. The flower/vegetable farming group reported the highest frequency of good exposure prevention practices during pesticide use. They were the most likely to report using cotton or rubber gloves or a disposable paper masks during insecticide spraying. Those farmers who only grew vegetables had the lowest frequency of good exposure prevention practices, including use of personal protective equipment. The economic cost of work-related injuries and illnesses among informal sector agricultural workers in Thailand is unknown and in need of study. Gaps in the regulations covering pesticide sales allow farmers to purchase pesticides without adequate training in their safe use. Training targeted to farm type regarding safe pesticide use and the prevention of accidents and musculoskeletal disorders is needed. Studies of chronic health effects among Thai farmers are needed, with special emphasis on respiratory, metabolic disease and cancer.