Assessment of personal inhalation and skin exposures to polymeric methylene diphenyl diisocyanate during polyurethane fabric coating.

Methylene diphenyl diisocyanate (MDI) monomers and polymeric MDI (pMDI) are aromatic isocyanates widely used in the production of polyurethanes. These isocyanates can cause occupational asthma, hypersensitivity pneumonitis, as well as contact dermatitis. Skin exposure likely contributes toward initial sensitization but is challenging to monitor and quantitate. In this work, we characterized workers' personal inhalation and skin exposures to pMDI in a polyurethane fabric coating factory for subsequent health effect studies. Full-shift personal and area air samples were collected from eleven workers in representative job areas daily for 1-2 weeks. Skin exposure to hands was evaluated concomitantly with a newly developed reagent-impregnated cotton glove dosimeter. Samples were analyzed for pMDI by liquid chromatography-tandem mass spectrometry. In personal airborne samples, the concentration of 4,4'-MDI isomer, expressed as total NCO, had a geometric mean (GM) and geometric standard deviation (GSD) of 5.1 and 3.3 ng NCO/m3, respectively (range: 0.5-1862 ng NCO/m3). Other MDI isomers were found at much lower concentrations. Analysis of 4,4'-MDI in the glove dosimeters exhibited much greater exposures (GM: 10 ng/cm2) and substantial variability (GSD: 20 ng NCO/cm2; range: 0-295 ng NCO/cm2). MDI inhalation exposure was well below occupational limits for MDI for all the job areas. However, MDI skin exposure to hands was substantial. These findings demonstrated the potential for substantial isocyanate skin exposure in work settings with very low airborne levels. This exposure characterization should inform future studies that aim to assess the health effects of work exposures to MDI and the effectiveness of protective measures.

Pesticide residues on children's hands, home indoor surfaces, and drinking water among conventional and organic farmers in Thailand.

This study measured pesticide levels on children's hands, home indoor surfaces, and drinking water among Thai conventional and organic farm families in three provinces. Farm families in Nakhonsawan and Phitsanulok provinces were the conventional farmers and those in Yasothon province were the organic farmers. Samples were collected in the dry and wet seasons over 2 years (2017 and 2018). All samples were analyzed for organophosphates (OPs), carbamate, pyrethroid, triazines, glyphosate, and aminomethylphosphonic acid (AMPA). On children's hands, the highest concentrations for the 2 palmar surfaces were found for cypermethrin (7.46 µg) and fipronil (2.88 µg). On home surfaces of approximately 1000 cm2, the highest concentrations were found for cypermethrin (27.94 µg) and fipronil 49.76 µg)/1000 cm2. For the conventional farmers, the most common pesticides on children's hand wipes were cypermethrin and fipronil, which are used as in-home pesticides as well as agricultural pesticides. However, home surface wipes showed other pesticides associated with agriculture were presented in the home during the seasons when they were used, suggesting spray drift or carry home sources for these pesticides. During the wet season, pesticides were found in the drinking water of all provinces. Most common were fenitrothion, profenofos, fenthion, atrazine, and AMPA. Profenofos was found at levels above the health guidelines. During 2017, there was extensive flooding in Thailand which may have contributed to the drinking water contamination, even though most farmers report using tap water or bottled drinking water. Future work is needed to assess the risk of all sources of pesticide exposures in children and to repeat the drinking water pesticide contamination analysis.

Hydrogeogenic fluoride in groundwater and dental fluorosis in Thai agrarian communities: a prevalence survey and case-control study.

BACKGROUND: Dental fluorosis can be a disease of social inequity in access to safe drinking water. This dental public health issue becomes prominent in socially disadvantaged agrarian communities in fluoride endemic areas where the standard irrigation system is unavailable and groundwater containing natural fluoride is the major drinking water source. This study aimed to determine the prevalence and severity of dental fluorosis in children and to evaluate its association with fluoride in groundwater in the aforementioned setting in Thailand. METHODS: A cross-sectional survey of 289 children in Nakhon Pathom Province was conducted in 2015. Children with very mild to severe fluorosis were regarded as 'cases' while their counterparts were 'controls' for a subsequent case-control study. Records of fluoride concentrations in groundwater used for household supply corresponding to resident and number of years by age of each child during 2008-2015 were retrieved. Other exposure variables were measured using a questionnaire. Prevalence ratio (PR), a measure indicating the relative effect of different levels of fluoride on dental fluorosis, was obtained from Poisson regression with robust standard error. RESULT: There were 157 children with very mild to moderate dental fluorosis (54.3% prevalence). The univariable analysis revealed that the prevalence of dental fluorosis among children with fluoride concentrations in water sources of 0.7-1.49 (index category 1) and ≥ 1.5 ppm (index category 2) was 1.62 (95% CI; 0.78, 3.34) and 2.75 (95% CI; 1.42, 5.31) times the prevalence among those with fluoride < 0.7 ppm (referent category). After adjusting for all covariates, the adjusted prevalence ratios in both index categories were 1.64 (95% CI; 0.24, 11.24) and 2.85 (95% CI; 0.44, 18.52) which were close to their corresponding crude estimates. Since the magnitude of confounding, measured by (PRcrude-PRadjusted)/PRadjusted, were less than 10% for both index categories; this indicated the limited confounding effect of all covariates. CONCLUSIONS: In fluoride endemic areas, groundwater containing natural fluoride utilized for household consumption resulted in high dental fluorosis prevalence, particularly in the groundwater with fluoride concentrations of ≥ 1.5 ppm.

ORGANOPHOSPHATES IN MECONIUM OF NEWBORN BABIES WHOSE MOTHERS RESIDED IN AGRICULTURAL AREAS OF THAILAND.

Organophosphates (OPs) are widely used for pest and weed control in many countries including Thailand. In addition to causing environmental pollution, OPs affect human health by overstimulating neurotoxicants, and OP exposure during pregnancy can lead to adverse health effects of mothers and their fetuses. Using gas chromatography-mass spectrometry with a dedicated extraction protocol to identify OPs in meconium of newborn babies (n = 68) from hospitals in Amnat Charoen, Kanchanaburi and Nakhon Sawan provinces, agricultural regions of Thailand, among ten OP types analyzed, eight were detected in 98% of meconium samples (chlorpyrifos (median ± interquartile range (IQR) 0.08 ± 0.03-0.16 µg/g) in 32% of samples, demeton-s-methyl (0.35 ± 0.26-0.49 µg/g) in 73%, dichlorvos (0.67 ± 0.58-0.71 µg/g) in 38%, dimethoate (0.43 ± 0.09-1.56 µg/g) in 50%, ethion (0.21 ± 0.19-0.26 µg/g) in 12%, malathion (0.28 ± 0.15-0.52 µg/g) in 50%, omethoate (5.63 ± 4.85-8.57 µg/g) in 34%, and tolclofos-methyl (0.08 ± 0.03-0.10 µg/g) in 41%). There are no significant differences in these parameters from babies whose mothers did and did not work in the agricultural or who lived near (within one km) and distant from farmland. The findings should be of benefit in developing programs to protect pregnant women and newborn babies from exposure to OP pesticides.

Asthma, COPD, and home environments: Interventions with older adults.

BACKGROUND: We describe a multifaceted home environmental intervention project involving low-income older adults with asthma who have a greater risk of asthma-related respiratory impacts because they spend up to 90% of their time in the home where many allergens and respiratory irritants are found. Although sufficient evidence suggests that home interventions are effective in improving health of children with asthma, the Task Force on Community Preventive Services has stated that evidence is insufficient for the effectiveness of home interventions on adults with asthma. OBJECTIVE: To evaluate the hypothesis that multifaceted home environmental interventions improve the respiratory health and reduce asthma triggers for older adults with asthma. METHODS: We conducted community health worker-led interventions in the homes of 86 low-income older adults (age 62 or older) diagnosed with asthma, residing in public and private subsidized housing in Lowell, Massachusetts, from 2014 to 2017. Health and environmental assessment at baseline and follow-up 1 year later included collecting data on respiratory health, quality of life, medication use, doctor/emergency room/hospital visits, using the St. George Respiratory Questionnaire and Asthma Control Test and evaluation of asthma trigger activities and exposures through questionnaires and home surveys. Interventions included education on asthma and environmental triggers and environmental remediation. RESULTS: Statistically significant reductions in self-reported environmental asthma triggers and health improvements were found in the following areas: doctor visits, use of antibiotics for chest problems, respiratory symptoms and quality of life indicators, and asthma control (ACT score). CONCLUSION: Our results provide evidence that multifaceted home interventions are effective in improving the environmental quality and respiratory health of an older adult population with asthma.

Development of an Interception Glove Sampler for Skin Exposures to Aromatic Isocyanates.

OBJECTIVES: Skin is an important exposure route for isocyanate chemicals and contributes to systemic sensitization. Methods for assessing skin exposure are currently limited and generally rely upon removal (e.g. tape-strip) techniques prone to underestimation. The aim of this study is to (i) develop and field test an interception-based hand exposure sampler to monitor potential skin exposure to isocyanates in the workplace, (ii) to develop an analytical method based on ultra-high-performance liquid chromatography-UV absorbance-tandem mass spectrometry (UHPLC-UV-MS/MS) for analyzing glove samples; and (iii) compare it with tape-stripping skin sampling method. METHODS: Laboratory investigations assessed different glove materials/fabrics, methods for impregnating with 1-(9-anthracenylmethyl)piperazine (MAP) derivatizing agent, methylene diphenyl diisocyanate (MDI) uptake and recovery, and durability. Following use, gloves were dissected into sections corresponding to different spatial regions (finger, palm) and analyzed using a newly developed UHPLC-UV-MS/MS method capable of differentiating and quantitating different MDI isomers with high sensitivity. Performance of the glove sampler was further assessed in a pilot field study using six workers. RESULTS: A MAP-impregnated thin cotton glove sampler and UHPLC-UV-MS/MS analytical method for detecting MDI were successfully developed in laboratory studies. In subsequent field studies, a total of 384 samples from 14 glove pairs identified full-shift exposures ranged from 0.01 to 306 µg of 4,4'-MDI/worker for each hand. Surface area adjusted MDI values measured with the glove sampler (0.13-572ng MDI cm-2) were considerably higher (~400-fold) than values obtained with tape stripping. CONCLUSION: A glove sampler and a novel UHPLC-UV-MS/MS analytical method were developed to quantitatively measure MDI skin exposure. The novel interception technique overcomes inherent limitations of removal techniques for measuring isocyanate skin exposure and may be useful in exposure surveillance and future research on isocyanate's health risks.

Characterization of Potential Exposures to Nanoparticles and Fibers during Manufacturing and Recycling of Carbon Nanotube Reinforced Polypropylene Composites.

Carbon nanotube (CNT) polymer composites are widely used as raw materials in multiple industries because of their excellent properties. This expansion, however, is accompanied by realistic concerns over potential release of CNTs and associated nanoparticles during the manufacturing, recycling, use, and disposal of CNT composite products. Such data continue to be limited, especially with regards to post-processing of CNT-enabled products, recycling and handling of nanowaste, and end-of-life disposal. This study investigated for the first time airborne nanoparticle and fibers exposures during injection molding and recycling of CNT polypropylene composites (CNT-PP) relative to that of PP. Exposure characterization focused on source emissions during loading, melting, molding, grinding, and recycling of scrap material over 20 cycles and included real-time characterization of total particle number concentration and size distribution, nanoparticle and fiber morphology, and fiber concentrations near the operator. Total airborne nanoparticle concentration emitted during loading, melting, molding, and grinding of CNT-PP had geometric mean ranging from 1.2 × 10(3) to 4.3 × 10(5) particles cm(-3), with the highest exposures being up to 2.9 and 300.7 times above the background for injection molding and grinding, respectively. Most of these emissions were similar to PP synthesis. Melting and molding of CNT-PP and PP produced exclusively nanoparticles. Grinding of CNT-PP but not PP generated larger particles with encapsulated CNTs, particles with CNT extrusions, and respirable fiber (up to 0.2 fibers cm(-3)). No free CNTs were found in any of the processes. The number of recycling runs had no significant impact on exposures. Further research into the chemical composition of the emitted nanoparticles is warranted. In the meanwhile, exposure controls should be instituted during processing and recycling of CNT-PP.

Healthy homes: in-home environmental asthma intervention in a diverse urban community.

OBJECTIVES: We evaluated health outcomes associated with in-home interventions in low-income urban households with children with asthma. METHODS: A comprehensive health and environmental assessment and subsequent intervention were completed in 116 households with 170 enrolled children with asthma. Home health workers provided household safety, asthma prevention education, and targeted environmental intervention to decrease asthma triggers and improve household safety. We collected environmental data with questionnaire and dust samples and health information with a questionnaire incorporating the American Academy of Pediatrics Children's Health Survey for Asthma and other instruments at baseline and at follow-up 11 to 12 months later to evaluate the impact of the intervention on the health of the child and family in Lowell, Massachusetts, from September 2009 to January 2012. RESULTS: The diverse study population of low-income children showed a statistically significant health improvement from baseline to follow-up. The cost of the interventions (not including personnel) was $36 240, whereas the estimated medical savings over a 4-week assessment period was $71 162, resulting in an estimated annual savings of about $821 304. CONCLUSIONS: Low-cost, multicomponent interventions decrease all measures of asthma severity and health care utilization in a diverse population of urban children.

Retrospective assessment of exposure to chemicals for a microelectronics and business machine manufacturing facility.

A retrospective exposure assessment was performed for use in a health outcomes study of a facility manufacturing circuit boards, business machines, and other equipment during the years 1969-2002. A matrix was developed identifying chemical use by department-year based on company-provided information. Use of six chemical agents (fiberglass, lead, methylene chloride, methyl chloroform, perchloroethylene, and trichloroethylene) and six chemical classes (acid-base, aromatic hydrocarbons, chlorinated hydrocarbons, other hydrocarbons, chlorofluorocarbons, and metals), and general (including unspecified) chemicals was identified. The matrix also contained an assignment for each department-year categorizing the potential for use of chemicals as negligible, intermittent/incidental, or routine. These department-based exposure matrix data were combined with work history data to provide duration of potential chemical use for workers. Negligible, intermittent/incidental or routine extent-of-chemical-use categories comprised 42.6%, 39.4%, and 17.9%, respectively, of total person-years of employment. Cumulative exposure scores were also developed, representing a relative measure of the cumulative extent of potential exposure to the six chemical agents, six chemical classes, and general (including unspecified) chemicals. Additionally, the study period was divided into manufacturing eras showing trends in chemical use, and showing that process use of trichloroethylene and methylene chloride ended in the mid-1980s and the mid-1990s, respectively. This approach may be useful in other assessments addressing a variety of chemicals, and with data constraints common to retrospective chemical exposure studies.

Evaluation of leakage from fume hoods using tracer gas, tracer nanoparticles and nanopowder handling test methodologies.

The most commonly reported control used to minimize workplace exposures to nanomaterials is the chemical fume hood. Studies have shown, however, that significant releases of nanoparticles can occur when materials are handled inside fume hoods. This study evaluated the performance of a new commercially available nano fume hood using three different test protocols. Tracer gas, tracer nanoparticle, and nanopowder handling protocols were used to evaluate the hood. A static test procedure using tracer gas (sulfur hexafluoride) and nanoparticles as well as an active test using an operator handling nanoalumina were conducted. A commercially available particle generator was used to produce sodium chloride tracer nanoparticles. Containment effectiveness was evaluated by sampling both in the breathing zone (BZ) of a mannequin and operator as well as across the hood opening. These containment tests were conducted across a range of hood face velocities (60, 80, and 100 ft/min) and with the room ventilation system turned off and on. For the tracer gas and tracer nanoparticle tests, leakage was much more prominent on the left side of the hood (closest to the room supply air diffuser) although some leakage was noted on the right side and in the BZ sample locations. During the tracer gas and tracer nanoparticle tests, leakage was primarily noted when the room air conditioner was on for both the low and medium hood exhaust airflows. When the room air conditioner was turned off, the static tracer gas tests showed good containment across most test conditions. The tracer gas and nanoparticle test results were well correlated showing hood leakage under the same conditions and at the same sample locations. The impact of a room air conditioner was demonstrated with containment being adversely impacted during the use of room air ventilation. The tracer nanoparticle approach is a simple method requiring minimal setup and instrumentation. However, the method requires the reduction in background concentrations to allow for increased sensitivity.

Mental Health Disorders among Thai Farmers: Occupational and Non-Occupational Stressors.

This cross-sectional study aimed to identify occupational and non-occupational factors that impact levels of stress, depression, and anxiety among farmers located in the northern part of Thailand, including the potential psychological impacts of pesticide use. The participants (N=270) were interviewed with a survey adopted and modified from peer-reviewed articles and questionnaires. The survey consists of four parts, including demographic information and pesticide exposure; perceived farm stressors employing Farm Stressor Survey (FSS); mental health disorder utilizing Srithanya Stress Scale (ST5), Nine-Questions Depression- Rating Scale (9Q), and Depression Anxiety Stress Scale 21 (DASS21); in addition to COVID-related stress utilizing COVID Stress Scale (CSS). The participants were categorized into two groups i.e., Spray and No Spray based on their self-reported occupational use of pesticide spraying within the past year. No significant associations were observed between occupational pesticide exposures and mental health disorder scores. Being female, having a second job besides a farmer, having applied pesticides for greater than 20 years, and having a higher farm stressor perception showed a significant positive association with self-reported mental health disorders; while having a good agricultural practice and PPE use showed a significant negative association with those outcomes. This pilot study scrutinized expanded sources of stress in farm work and provided information for the development of more effective mental disorder intervention programs for Thai farmers.

Evaluation of disposable protective garments against epoxy resin permeation and penetration from anti-corrosion coatings.

INTRODUCTION: Epoxy-based resin formulations are a frequent cause of allergic and irritant contact dermatitis in the construction and painting industries. Cases of epoxy resin contact dermatitis continue to persist across many sectors and are likely attributable to the growing use of epoxy products, including epoxy-based anti-corrosion coatings and inadequate skin protection. There are no published performance data against epoxy resins for garment materials and gloves to guide proper material selection in the workplace. OBJECTIVES: The objective of this study was to evaluate the resistance of 5 protective garment materials against permeation and penetration by bisphenol A diglycidyl ether and its higher oligomers found commonly in epoxy-based anti-corrosion coatings. METHODS: Five disposable garment materials were evaluated for resistance to bisphenol A diglycidyl ether monomers and oligomers during contact with epoxy-based anti-corrosion coatings, including latex gloves, nitrile gloves, Tyvek coveralls, polypropylene/polyethylene (PP/PE) coveralls, and a cotton T-shirt. A permeation test cell system was used to evaluate each garment material against an epoxy-based zinc-rich primer and an epoxy-based intermediate coating using a realistic application method. Glass fiber filters were used to collect permeating and penetrating epoxy resin during a 120-min test period. Bisphenol A diglycidyl ether quantification was performed with high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. Paint loading, coating thickness, and homogeneity were assessed on polytetrafluoroethylene filters sprayed in series in permeation test cells. RESULTS: Latex gloves provided the least resistance to permeation by BADGE in coating formulations, with a maximum cumulative permeation over the 2-h test interval of 21.7 ng cm-2 with the primer and 513.8 ng cm-2 with the intermediate coating product. Nitrile gloves were not permeated by either coating formulation. The Tyvek coveralls provided greater protection as compared to the PP/PE coveralls. The cotton T-shirt was penetrated by bisphenol A diglycidyl ether more frequently than any of the tested garment materials and resulted in a maximum cumulative penetration of 128 ng cm-2 with the primer and 28.0 ng cm-2 with the intermediate coating. CONCLUSION: Although all the garment materials evaluated during this study provided sufficient protection to prevent cumulative permeation in excess of the established acceptable permeation thresholds, the use of nitrile gloves and Tyvek coverall is highly recommended to minimize skin exposure to bisphenol A diglycidyl ether. We recommend cotton T-shirts to be used under Tyvek coveralls as a secondary layer of skin protection and for added comfort, but not as a primary protection layer.

Deployment to Military Bases With Open Burn Pits and Respiratory and Cardiovascular Disease.

Importance: Many veterans who served in Afghanistan and Iraq during Operations Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) were deployed to military bases with open burn pits and exposed to their emissions, with limited understanding of the long-term health consequences. Objective: To determine the association between deployment to military bases where open burn pits were used for waste disposal and the subsequent risk of developing respiratory and cardiovascular diseases. Design, Setting, and Participants: This retrospective observational cohort study used Veterans Health Administration medical records and declassified deployment records from the Department of Defense to assess Army and Air Force veterans who were deployed between 2001 and 2011 and subsequently received health care from the Veterans Health Administration, with follow-up through December 2020. Data were analyzed from January 2023 through February 2024. Exposure: Duration of deployment to military bases with open burn pits. Main Outcomes and Measures: Diagnosis of asthma, chronic obstructive pulmonary disease, interstitial lung disease, hypertension, myocardial infarction, congestive heart failure, ischemic stroke, and hemorrhagic stroke. Results: The study population included 459 381 OEF and OIF veterans (mean [SD] age, 31.6 [8.7] years; 399 754 [87.0%] male). Median (IQR) follow-up from end of deployment was 10.9 (9.4-12.7) years. For every 100 days of deployment to bases with burn pits, veterans experienced increased adjusted odds for asthma (adjusted odds ratio [aOR], 1.01; 95% CI, 1.01-1.02), chronic obstructive pulmonary disease (aOR, 1.04; 95% CI, 1.02-1.07), hypertension (aOR, 1.02; 95% CI, 1.02-1.03), and ischemic stroke (aOR, 1.06; 95% CI, 0.97-1.14). Odds of interstitial lung disease, myocardial infarction, congestive heart failure, or hemorrhagic stroke were not increased. Results based on tertiles of duration of burn pit exposures were consistent with those from the continuous exposure measures. Conclusions and Relevance: In this cohort study, prolonged deployment to military bases with open burn pits was associated with increased risk of developing asthma, COPD, and hypertension. The results also point to a possible increased risk in ischemic stroke. The novel ability to use integrated data on deployment and health outcomes provides a model for additional studies of the health impact of environmental exposures during military service.

Evaluation of cytotoxic, genotoxic and inflammatory responses of nanoparticles from photocopiers in three human cell lines.

BACKGROUND: Photocopiers emit nanoparticles with complex chemical composition. Short-term exposures to modest nanoparticle concentrations triggered upper airway inflammation and oxidative stress in healthy human volunteers in a recent study. To further understand the toxicological properties of copier-emitted nanoparticles, we studied in-vitro their ability to induce cytotoxicity, pro-inflammatory cytokine release, DNA damage, and apoptosis in relevant human cell lines. METHODS: Three cell types were used: THP-1, primary human nasal- and small airway epithelial cells. Following collection in a large volume photocopy center, nanoparticles were extracted, dispersed and characterized in the cell culture medium. Cells were doped at 30, 100 and 300 µg/mL administered doses for up to 24 hrs. Estimated dose delivered to cells, was ~10% and 22% of the administered dose at 6 and 24 hrs, respectively. Gene expression analysis of key biomarkers was performed using real time quantitative PCR (RT-qPCR) in THP-1 cells at 5 µg nanoparticles/mL for 6-hr exposure for confirmation purposes. RESULTS: Multiple cytokines, GM-CSF, IL-1ß, IL-6, IL-8, IFNγ, MCP-1, TNF-α and VEGF, were significantly elevated in THP-1 cells in a dose-dependent manner. Gene expression analysis confirmed up-regulation of the TNF-α gene in THP-1 cells, consistent with cytokine findings. In both primary epithelial cells, cytokines IL-8, VEGF, EGF, IL-1α, TNF-α, IL-6 and GM-CSF were significantly elevated. Apoptosis was induced in all cell lines in a dose-dependent manner, consistent with the significant up-regulation of key apoptosis-regulating genes P53 and Casp8 in THP-1 cells. No significant DNA damage was found at any concentration with the comet assay. Up-regulation of key DNA damage and repair genes, Ku70 and Rad51, were also observed in THP-1 cells, albeit not statistically significant. Significant up-regulation of the key gene HO1 for oxidative stress, implicates oxidative stress induced by nanoparticles. CONCLUSIONS: Copier-emitted nanoparticles induced the release of pro-inflammatory cytokines, apoptosis and modest cytotoxicity but no DNA damage in all three-human cell lines. Taken together with gene expression data in THP-1 cells, we conclude that these nanoparticles are directly responsible for inflammation observed in human volunteers. Further toxicological evaluations of these nanoparticles, including across different toner formulations, are warranted.

Toxicological effects of PM0.25-2.0 particles collected from a photocopy center in three human cell lines.

Printing devices such as photocopiers and printers emit predominantly nanoparticles, which may aggregate with time to form PM0.25-2.0 particles. To date, there are no reports on cytotoxic or genotoxic effects of PM0.25-2.0 particles emitted from photocopiers. To investigate the ability of PM0.25-2 fraction emitted from photocopiers, induce pro-inflammatory cytokines, DNA damage and apoptosis in different human-derived cell lines. Three cell types, i.e. a THP-1 line, primary human nasal and small airway epithelial cells, were used. The airborne PM0.25-2.0 size fraction collected from a photocopy center was characterized for its physicochemical and morphological properties, dispersed in culture media and cells were treated with 30, 100 or 300 µg/ml doses. Levels of 13 cytokines and chemokines in the culture medium harvested at 6 and 24 h of treatment were measured using Luminex cytokine kits. In cells harvested at the same timepoints, DNA damage in cells was studied by a Comet assay, and apoptosis was measured by cytofluorimetry using an Annexin V staining kit. The results indicate that in THP-1 cells, several cytokines (IL-6, IL-8, TNFα and IL-1ß) were significantly elevated. Only IL-8 was significantly elevated in the primary nasal and small airway cells. Cells exposed to PM0.25-2.0 underwent apoptosis in a dose-dependent manner, but no significant differences were found in the extent of DNA damage at either timepoint. Airborne PM0.25-2.0 collected at one photocopier center was capable of inducing several pro-inflammatory cytokines and apoptosis, but no genotoxicity, in all cell lines suggesting a role for PM0.25-2.0 in our previously documented airway inflammation in human volunteers. Further toxicological evaluations of these particles across different toner manufacturers are warranted.

Noise exposure reconstruction and evaluation of exposure trends in two large automotive plants.

This study used a task-based approach to reconstruct employee noise exposures at two large automotive manufacturing plants for the period 1970-1989, utilizing historic noise measurement data, work history records, documented changes in plant operations, focus group discussions, structured interviews with long-tenure employees, and task-based job profiles. Task-based job noise exposure profiles were developed in the 1990s when the plants conducted task-based noise monitoring. Under the assumption that tasks and time-at-task profile within jobs did not change over time, these profiles were applied to historic jobs. By linking historic noise exposure measurements to job tasks, this approach allowed task-based reconstructed noise exposure profiles to capture variability of daily noise exposures. Reconstructed noise exposures, along with task-based noise exposure measurements collected at each plant during the 1990s, were analyzed to examine time trends in workplace noise levels and worker noise exposure. Our analysis of noise exposure trends revealed that noise levels for many jobs declined by ≥3 dBA from 1970 to 1998 as operational and equipment changes occurred in the plants and some noise control measures were implemented, but for some jobs, noise levels increased in the mid- to late 1990s, most likely because of an increase in production at that time. Overall, the percentage of workers exposed to noise levels >90 dBA decreased from 95% in 1970 to 54% in 1998 at one of the plants and decreased from 36% in 1970 to ~5% in 1999 at the other plant. These reductions indicate a degree of success for the hearing conservation program. However, the actual number of employees with noise exposure >90 dBA increased because of a substantial increase in the number of production employees, particularly in jobs with high noise levels, which shows a hearing conservation program challenge that companies face during periods of increased production. Future analysis of hearing levels in these plant populations will help determine whether noise level reduction translates into decreased hearing loss at these plants.

Controlling dust from concrete saw cutting.

Cutting concrete with gas-powered saws is ubiquitous in the construction industry and a source of exposure to respirable crystalline silica. Volunteers from the New England Laborers Training Center were recruited to participate in a field experiment examining dust reductions through the use of water, from a hose and from a sprayer, as a dust control. In four series of tests, reinforced concrete pipe was cut under both "dry" and "wet" control conditions. Overall, the geometric mean respirable dust concentration for "dry" cutting (14.396 mg/m³) exceeded both types of water-based controls by more than tenfold. Wet cutting reduced the respirable dust concentration by 85% compared with dry cutting when comparing tests paired by person and saw blade (n = 79 pairs). Using a respirable cyclone, a total of 178 samples were taken. Due to the high variability in dust exposure found in this and other studies of saw cutting, the data were examined for potential exposure determinants that contribute to that variability. Using mixed models, three fixed effects were statistically significant: control condition, worker experience, and location. A random effect for subject was included in the model to account for repeated measures. When each of the significant fixed effects was included with the random effect, it was apparent that inclusion of worker experience or location reduced the between-worker component of exposure variability, while inclusion of control condition (wet vs. dry) explained a large portion of the within-subject variability. Overall, the fixed effect variable for control condition explained the largest fraction of the total exposure variability.

Urinary Cypermethrin Metabolites among Conventional and Organic Farmers in Thailand.

Cypermethrin, a pyrethroid insecticide, is frequently spread on agricultural farmlands and is also used in households in Thailand. Conventional pesticide-using farmers (n = 209) were recruited from the Phitsanulok and Nakornsawan provinces. Certified organic farmers (n = 224) were also recruited in the Yasothorn province. The farmers were interviewed via a questionnaire and the urine from their first morning void was collected. The urine samples were analyzed for 3-phenoxybenzoic acid (3-PBA), cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA), and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (trans-DCCA). The results showed no significant difference in the urinary cypermethrin metabolites between the conventional farmers and the organic farmers, for whom the usage of cypermethrin was not accounted for. However, when conventional farmers who used cypermethrin on the farm and in the home were compared with conventional farmers who did not use any cypermethrin or with organic farmers, a significant difference was noted for all metabolites except for trans-DCCA. These findings show that the most significant exposures to cypermethrin are among conventional farmers who use the insecticide on their farms or in their homes. However, measurable levels of all metabolites were found among both conventional and organic farmers who only used cypermethrin in the home or not at all, suggesting that the at-home use of pyrethroids and other possible exposures from pyrethroid residues on market-bought food may contribute to urinary levels of pyrethroids that exceed those of the general population in the US and Canada.

Burn Pit Exposure Assessment to Support a Cohort Study of US Veterans of the Wars in Iraq and Afghanistan.

OBJECTIVE: For a cohort study of veterans' health conditions, we conducted an exposure assessment for 109 bases in Iraq and Afghanistan and 17 outside transit site bases. METHODS: The Department of Defense records were used to determine burn pit usage and waste disposal methods for each base in each year during the period of 2001 to 2014. RESULTS: In the final cohort of 475,326 veterans, who had more than 80% of their deployment time characterized by our exposure matrix, only 14.5% were found to have no burn pit exposure. The 2009 Department of Defense regulations on burn pits did produce changes in waste segregation, as well as adding incineration and local disposal of waste. CONCLUSION: Most Iraq and Afghanistan veterans were stationed on bases that had burn pits, although the contents disposed of in the burn pits changed over time.