Increase in oxidative stress levels following welding fume inhalation: a controlled human exposure study.

BACKGROUND: Tungsten inert gas (TIG) welding represents one of the most widely used metal joining processes in industry. It has been shown to generate a large majority of particles at the nanoscale and to have low mass emission rates when compared to other types of welding. Despite evidence that TIG fume particles may produce reactive oxygen species (ROS), limited data is available for the time course changes of particle-associated oxidative stress in exposed TIG welders. METHODS: Twenty non-smoking male welding apprentices were exposed to TIG welding fumes for 60 min under controlled, well-ventilated settings. Exhaled breathe condensate (EBC), blood and urine were collected before exposure, immediately after exposure, 1 h and 3 h post exposure. Volunteers participated in a control day to account for oxidative stress fluctuations due to circadian rhythm. Biological liquids were assessed for total reducing capacity, hydrogen peroxide (H2O2), malondialdehyde (MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations at each time point. A linear mixed model was used to assess within day and between day differences. RESULTS: Significant increases in the measured biomarkers were found at 3 h post exposure. At 3 h post exposure, we found a 24 % increase in plasma-H2O2 concentrations ([95%CI: 4 % to 46 %], p = 0.01); a 91 % increase in urinary-H2O2 ([2 % to 258 %], p = 0.04); a 14 % increase in plasma-8-OHdG ([0 % to 31 %], p = 0.049); and a 45 % increase in urinary-8-OHdG ([3 % to 105 %], p = 0.03). Doubling particle number concentration (PNC) exposure was associated with a 22 % increase of plasma-8-OHdG at 3 h post exposure (p = 0.01). CONCLUSION: A 60-min exposure to TIG welding fume in a controlled, well-ventilated setting induced acute oxidative stress at 3 h post exposure in healthy, non-smoking apprentice welders not chronically exposed to welding fumes. As mass concentration of TIG welding fume particles is very low when compared to other types of welding, it is recommended that additional exposure metrics such as PNC are considered for occupational risk assessments. Our findings highlight the importance of increasing awareness of TIG welding fume toxicity, especially given the realities of welding workplaces that may lack ventilation; and beliefs among interviewed welders that TIG represents a cleaner and safer welding process.

Characterization of Tungsten Inert Gas (TIG) Welding Fume Generated by Apprentice Welders.

Tungsten inert gas welding (TIG) represents one of the most widely used metal joining processes in industry. Its propensity to generate a greater portion of welding fume particles at the nanoscale poses a potential occupational health hazard for workers. However, current literature lacks comprehensive characterization of TIG welding fume particles. Even less is known about welding fumes generated by welding apprentices with little experience in welding. We characterized TIG welding fume generated by apprentice welders (N = 20) in a ventilated exposure cabin. Exposure assessment was conducted for each apprentice welder at the breathing zone (BZ) inside of the welding helmet and at a near-field (NF) location, 60cm away from the welding task. We characterized particulate matter (PM4), particle number concentration and particle size, particle morphology, chemical composition, reactive oxygen species (ROS) production potential, and gaseous components. The mean particle number concentration at the BZ was 1.69E+06 particles cm(-3), with a mean geometric mean diameter of 45nm. On average across all subjects, 92% of the particle counts at the BZ were below 100nm. We observed elevated concentrations of tungsten, which was most likely due to electrode consumption. Mean ROS production potential of TIG welding fumes at the BZ exceeded average concentrations previously found in traffic-polluted air. Furthermore, ROS production potential was significantly higher for apprentices that burned their metal during their welding task. We recommend that future exposure assessments take into consideration welding performance as a potential exposure modifier for apprentice welders or welders with minimal training.

Determinants of Pesticide Exposure in Occupational Studies: A Meta-Analysis.

Few epidemiological studies use exposure determinants specifically tailored to assess pesticide or plant protection product (PPP) exposures when assessing presumed association between occupational exposure and health outcomes among agricultural workers. This lack of exposure specificity could lead to results that fail to detect an association. It could be related to the lack of consensus on exposure assessment methods and the choice of exposure determinants. We conducted a meta-analysis following the PRISMA checklist to identify PPP exposure determinants used in occupational studies and identified exposure determinants that best characterized agricultural exposures to PPPs. Out of 1436 studies identified, 71 were included. The exposure determinants identified were active ingredients, chemical classes, types of PPP, crops, tasks, frequencies, duration, lifetime exposure days, and intensity-weighted exposure days. Only six over 17 associations between exposure determinants and health outcomes were found with moderate quality of evidence. Overall, epidemiological studies had difficulty defining relevant determinants to characterize PPP exposures for agricultural workers. We recommend that a standardized list of determinants for PPP exposures in occupational exposure studies should include information on formulations, intensity, duration, and frequency of PPP exposure. Harmonized data collection on exposure and health outcomes are required as well as standard units for each exposure determinant.

Skimmed Milk Applied as a Phytopharmaceutical Product: A Risk for Allergic Populations?

Milk allergy is among the most common food-related allergies. Milk-based products are recognized as plant protection products (PPPs) in several countries as alternatives to synthetic pesticides. The potential health risk for allergic workers, as well as the general population, is yet to be assessed. An investigation was conducted in the Vaud Canton of Switzerland, where milk-based products are sprayed by helicopter over vineyards. Air lactose concentration was measured at 14 locations via 25 mm IOM Multidust samplers. Residual lactose concentration was measured on the surface of leaves over 7 days following spraying. Surface contamination downwind from the treated area was estimated through computer-based modeling using AgDRIFT® software. The average milk protein concentration inside and outside the vineyard was 0.47 and 0.16 µg/m3, respectively. Milk residues persisted on the leaf surface for an average of three days. Modelling results revealed an estimated order of magnitude of 0.1-0.5 µg/m3 in milk proteins within one hour after the treatment in the close vicinity of the treated area. Our results reveal that the potential exposure to milk proteins in and around helicopter-treated vineyards is not negligible and that prevention messages targeted to individuals with severe allergies should be considered.

The role of the Swiss list of occupational diseases in the protection of workers' health.

Occupational disease lists (ODLs) are essential legal mechanisms for recognising pathologies related to exposure to occupational hazards. In 2017, Switzerland revised its ODL and solicited stakeholders to review the ODL proposal. This revision represented an important and rare event, and was an opportunity to assess the legal status and role of Swiss ODL. In this research, we examined the structure and content of this revised Swiss list, by comparing it to other official recommendations and ODLs, including those of the International Labour Organization (ILO) and the European Commission (EC). In addition, we assessed the effectiveness of the Swiss ODL from the occupational and public health perspectives, in considering the process of reporting and recognition of occupational diseases as a measure for protecting the health of workers. Although the Swiss ODL appears to be in accordance with the ILO and EC recommendations, its role as a legal mechanism of workers’ protection is not optimal. Its effectiveness is limited by the conditions for recognising a disease as occupational, which are determined by Swiss federal law and are stricter than in other countries. The overall burden of occupational diseases has a significant economic, social and moral impact on working populations, their families and society as a whole. As such, more transparency with respect to the ODL revision and conditions for recognising occupational disease and to the data on recognised and reported cases, along with continuous education of physicians are required to enhance the effectiveness of the Swiss system of recognition and reporting of occupational diseases and protection of Swiss workers.

Occupational exposure to inhaled nanoparticles: Are young workers being left in the dust?

OBJECTIVES: Occupational exposure to inhaled nanoparticles (NPs) represents a significant concern for worker health. Adolescent workers may face unique risks for exposure and resulting health effects when compared with adult workers. METHODS: This manuscript discusses key differences in risks for occupational exposures to inhaled NPs and resulting health effects between young workers and adult workers via an examination of both physiological and occupational setting factors. RESULTS: Previous studies document how adolescents often face distinct and unique exposure scenarios to occupational hazards when compared to adults. Moreover, they also face different and unpredictable health effects because biological functions such as detoxification pathways and neurological mechanisms are still developing well into late adolescence. Early exposure also increases the chances of developing long-latency disease earlier in life. Taken together, adolescents' rapid growth and development encompasses highly dynamic and complex processes. An aggravating factor is that these processes do not necessarily fall in line with legal classifications of adulthood, nor with occupational exposure limits created for adult workers. CONCLUSIONS: The differences in exposures and health consequences from NPs on young workers are insufficiently understood. Research is needed to better understand what adolescent-specific mitigation strategies may be most suitable to address these risk factors.

Occupational exposure to plant protection products and health effects in Switzerland: what do we know and what do we need to do?

AIMS: There is currently no centralised database on workers' exposures to plant protection products (PPPs) in Switzerland, nor a national register for negative health effects linking them to occupational PPP exposure. This lack of basic data makes it difficult to implement either epidemiological research or prevention campaigns for the agricultural sector. The first objective was to understand the level of information and flow of data on occupational PPP exposures and health effects in the Canton of Vaud, Switzerland. Then, to apply this information to develop recommendations for improving a vigilance system for occupational health effects related to PPP exposure. METHODS: A mapping study and semistructured stakeholder interviews were conducted to better understand the flow of data on occupational PPP exposures and health effects. A clinical records investigation of workers occupationally exposed to PPPs was undertaken to understand the magnitude of this potential problem. Finally, a workshop brought together relevant stakeholders to discuss recommendations for the way forwards. RESULTS: A lack of data on PPP exposures and associated health effects was revealed. This highlighted important knowledge gaps at different levels of the current institutional information flow system. We found that although there were numerous stakeholders that worked efficiently in their own mandate, there was a clear need for increased collaboration and coordination in order to make use of existing data to promote safer PPP use among agricultural workers in Switzerland. CONCLUSIONS: Due to increasing evidence of an association between PPP exposure and health effects, increased collaboration between stakeholders is necessary to develop links between the data sources that already exist. Our study was the first to investigate the health effects linked to PPP exposure among the Swiss agricultural population. The recommendations presented in this paper would help promote a safer and healthier agricultural workforce in Switzerland, as well as the population at large.

Occupational exposure limits for manufactured nanomaterials, a systematic review.

BACKGROUND: The toxicological properties of manufactured nanomaterials (MNMs) can be different from their bulk-material and uncertainty remains about the adverse health effects they may have on humans. Proposals for OELs have been put forward which can be useful for risk management and workers' protection. We performed a systematic review of proposals for OELs for MNMs to better understand the extent of such proposals, as well as their derivation methods. METHODS: We searched PubMed and Embase with an extensive search string and also assessed the references in the included studies. Two authors extracted the data independently. RESULTS: We identified 20 studies that proposed in total 56 OEL values. Of these, two proposed a generic level for all MNMs, 14 proposed a generic OEL for a category of MNMs and 40 proposed an OEL for a specific nanomaterial. For specific fibers, four studies proposed a similar value but for carbon nanotubes (CNTs) the values differed with a factor ranging from 30 to 50 and for metals with a factor from 100 to 300. The studies did not provide explanations for this variation. We found that exposure to MNMs measured at selected workplaces may exceed even the highest proposed OEL. This indicates that the application and use of OELs may be useful for exposure reduction. CONCLUSION: OELs can provide a valuable reference point for exposure reduction measures in workplaces. There is a need for more and better supported OELs based on a more systematic approach to OEL derivation.

Physicochemical characterization of nebulized superparamagnetic iron oxide nanoparticles (SPIONs).

BACKGROUND: Aerosol-mediated delivery of nano-based therapeutics to the lung has emerged as a promising alternative for treatment and prevention of lung diseases. Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted significant attention for such applications due to their biocompatibility and magnetic properties. However, information is lacking about the characteristics of nebulized SPIONs for use as a therapeutic aerosol. To address this need, we conducted a physicochemical characterization of nebulized Rienso, a SPION-based formulation for intravenous treatment of anemia. METHODS: Four different concentrations of SPION suspensions were nebulized with a one-jet nebulizer. Particle size was measured in suspension by transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and nanoparticle tracking analysis (NTA), and in the aerosol by a scanning mobility particle sizer (SMPS). RESULTS: The average particle size in suspension as measured by TEM, PCS, and NTA was 9±2 nm, 27±7 nm, and 56±10 nm, respectively. The particle size in suspension remained the same before and after the nebulization process. However, after aerosol collection in an impinger, the suspended particle size increased to 159±46 nm as measured by NTA. The aerosol particle concentration increased linearly with increasing suspension concentration, and the aerodynamic diameter remained relatively stable at around 75 nm as measured by SMPS. CONCLUSIONS: We demonstrated that the total number and particle size in the aerosol were modulated as a function of the initial concentration in the nebulizer. The data obtained mark the first known independent characterization of nebulized Rienso and, as such, provide critical information on the behavior of Rienso nanoparticles in an aerosol. The data obtained in this study add new knowledge to the existing body of literature on potential applications of SPION suspensions as inhaled aerosol therapeutics.

Occurrence of Cryptosporidium and Giardia in sewage sludge and solid waste landfill leachate and quantitative comparative analysis of sanitization treatments on pathogen inactivation.

Circulation of Cryptosporidum and Giardia in the environment can be facilitated by spreading of sewage sludge on agricultural or livestock grazing lands or depositing in landfills. Solid waste landfill leachate and sewage sludge samples were quantitatively tested for C. parvum and C. hominis oocysts, and G. lamblia cysts by the combined multiplexed fluorescence in situ hybridization (FISH) and immunofluorescent antibody (IFA) method. Subsequently, the effects of four sanitization treatments (i.e., ultrasound and microwave energy disintegrations, and quicklime and top-soil stabilization) on inactivation of these pathogens were determined. The landfill leachate samples were positive for Giardia, and sewage sludge samples for both Cryptosporididium and Giardia. The overall concentration of G. lamblia cysts (mean; 24.2/g) was significantly higher (P<0.01) than the concentration of C. parvum and C. hominis oocysts (mean; 14.0/g). Sonication reduced the load of G. lamblia cysts to non-detectable levels in 12 of 21 samples (57.1%), and in 5 of 6 samples (83.3%) for C. parvum and C. hominis. Quicklime stabilization treatment was 100% effective in inactivation of Cryptosporidium and Giardia, and microwave energy disintegration lacked the efficacy. Top-soil stabilization treatment reduced gradually the load of both pathogens which was consistent with the serial dilution of sewage sludge with the soil substrate. This study demonstrated that sewage sludge and landfill leachate contained high numbers of potentially viable, human-virulent species of Cryptosporidium and Giardia, and that sonication and quicklime stabilization were the most effective treatments for sanitization of sewage sludge and solid waste landfill leachates.

Human-virulent microsporidian spores in solid waste landfill leachate and sewage sludge, and effects of sanitization treatments on their inactivation.

Solid waste landfill leachate and sewage sludge samples were quantitatively tested for viable Enterocytozoon bieneusi, Encephalitozoon intestinalis, Encephalitozoon hellem, and Encephalitozoon cuniculi spores by the multiplexed fluorescence in situ hybridization (FISH) assay. The landfill leachate samples tested positive for E. bieneusi and the sludge samples for E. bieneusi and E. intestinalis. The effects of four sanitization treatments on the inactivation of these pathogens were assessed. Depending on the variations utilized in the ultrasound disintegration, sonication reduced the load of human-virulent microsporidian spores to nondetectable levels in 19 out of 27 samples (70.4%). Quicklime stabilization was 100% effective, whereas microwave energy disintegration was 100% ineffective against the spores of E. bieneusi and E. intestinalis. Top-soil stabilization treatment gradually reduced the load of both pathogens, consistent with the serial dilution of sewage sludge with the soil substrate. This study demonstrated that sewage sludge and landfill leachate contained high numbers of viable, human-virulent microsporidian spores, and that sonication and quicklime stabilization were the most effective treatments for the sanitization of sewage sludge and solid waste landfill leachates. Multiplexed FISH assay is a reliable quantitative molecular fluorescence microscopy method for the simultaneous identification of E. bieneusi, E. intestinalis, E. hellem, and E. cuniculi spores in environmental samples.