Approximately 92% of the land in Iowa, 64% in Indiana, and 27% in Michigan is agricultural farmland. Nearly 77% of farmland in Iowa and Indiana, and 58% of farmland in Michigan, were treated with herbicides in 2012 (USDA). Pesticide drift, or “overspray”, is defined as any off-site movement of pesticide during its application. Exposure to this drift has the potential to damage crops and landscaping, kill aquatic animals, and cause DNA damage, cancer, and allergic wheeze in applicators. The Pesticide Bureau of the Iowa Department of Agricultural and Land Stewardship (IDALS), the Indiana State Chemist (ISC), and the Michigan Department of Agriculture and Rural Development (MDARD) investigate complaints of pesticide misuse, including reports of pesticide drift. Individual narrative reports and case summaries are available, but have not been analyzed to identify contributing factors to prevent field, worker, and community exposures; nor has the community at large been surveyed about reporting practices. The aim of this research was to (1) identify determinants of pesticide drift events in the Midwest, comparing between states; (2) whether differing state policies were associated with drift characteristics and/or reporting of incidents; and (3) determine the proportion of events that occurred due to applicators ignoring pesticide label guidance. This examination will provide guidance when developing policies and prevention efforts used to minimize the hazards associated with pesticide drift. Narrative case reports from IDALS and MDARD, and case summaries from ISC spanning 2010-2016 were analyzed. Narratives and case summaries were converted to trackable data for ease of analysis using Excel. Data analysis includes descriptive statistics on continuous variables (e.g., distance, wind speed), chi-square tests, and t-tests. Analysis includes: crop damage associations with wind speed by chemical; ratio of human exposures across aerial applications, and associations of distance to target crop and reported plant damage. Key state policies were compared and the responses from a survey concerning the reporting of drift incidents was analyzed. The proportion of cases that violated weather and distance recommendations/label directions for the five most common pesticides in each were analyzed. Between 2010 and 2015, Iowa received 471 reported drift cases; between 2011 and 2016 Indiana received 391, and between 2014 and 2016 Michigan received 91 reports. The five most common pesticides analyzed for during drift investigations varied between states, but 2,4-D, glyphosate, and atrazine were common to all states. The method of application, (i.e., aerial or ground), wind speed, and the intended target crop were significantly associated with drift events across all three states. While Iowa was the only state to contain regulatory language concerning drift to bees or livestock, all states still reported 4 to 5% of cases in which pesticides drifted onto animals. Michigan was the only state to suggest the creation and use of a drift management plan and was the only state requiring applicators to inform neighbors of drift. About 30% of confirmed drift cases involved applications within 7.62 meters of desirable vegetation, and about 40% of applications occurred in wind greater than 4.5 m/s. More education, training, and community involvement are suggested interventions to reduce drift cases.

Clear evidence shows a relationship between working in swine facilities and developing respiratory illnesses. Health effects have been associated with exposures to the combination of dust, ammonia, and carbon dioxide (CO2). This study examined whether room concentrations of combustion gases could be improved by changing the in-room vented heaters common to animal production operations to heaters that vent combustion gases outside. Concentrations of CO2 and carbon monoxide (CO) were monitored during two winter seasons, with the 2013-14 season using the traditional gas-fired heater (Guardian 60, L.B.White Co.) and the 2014-15 winter using new vented heaters (Effinity93, Modine Manufacturing Co.) Direct-reading CO (VRAE, Rae Systems) and CO2 (ToxieRAE Pro, Rae Systems) monitors were deployed at fixed stations throughout the farrowing barn to measure gas concentrations. Differences in mean gas concentrations between heater types, as well as the relationship between CO2 and temperature, sow, and piglet count, were evaluated using linear regression. Carbon dioxide concentrations exceeded industry recommended limits (1540 ppm) on all sample days (N=18) with the standard in-room vented heaters in operation: concentrations averaged half of the TLV (2500 ppm). With the new vented heaters, 24-hour averaged CO2 concentrations exceeded industry recommended limits on only three out of 20 sample days: concentrations averaged 1400 ppm. The new heater significantly reduced CO2 by 44% and CO by 60% from 2.0 to 0.8 ppm (p2=0.75) between CO2 and production factors (temperature, sow and piglet count) for the new heater: CO2 (ppm) = 482 - 22.4(Temp °C) + 43(# sow) + 5.6(# piglet). Similar analysis for the old heater identified similar trends but substantially different intercept (1700 ppm) and temperature factor (-36.9). While CO2 is still generated from swine respiration, we found significant reductions in room concentrations with the simple replacement of commonly used equipment. Future work will include an assessment of the longevity of these heaters in the swine barn environment

The emergence of nanotechnology has increased the concern of exposure to nanoparticles through inhalation. Studies have examined the performance of filtering facepiece respirators against engineered nanoparticles. This has been done by the generation and dispersal of certain particles in a given size distribution, which have then been run through experimental set-ups involving Condensation Particle Counters, Scanning Mobility Particle Sizers, and high efficiency performance filters for a set flow. Published studies have shown that the respirators used do provide expected levels of filtration protection against nanometer-sized particles. However, studies have not examined or applied different types of nanoparticle samples - different particle types have differing morphologies and physical characteristics that could affect filter performance. This study has exposed NIOSH-approved N95 facepiece respirators to six different types of engineered nanoparticles: aluminum oxide, iron oxide, single-walled carbon nanotubes, synthesized diamond, silicon dioxide, and titanium dioxide. In addition, N95 respirators have not been commonly exposed to differing concentrations of an aerosol in order to observe a shift in the primary penetrating particle size and a shift in the overall size distribution. This study challenged N95 respirators to four different concentrations of sodium chloride: 0.1, 1, 10, and 50 mg/ml. Another concern is whether or not a prolonged exposure of a single respirator affects the overall performance and protection from an aerosol, especially engineered nanoparticles, since very few studies have been done regarding this matter. N95 respirators were exposed to several types of engineered nanoparticles in a respirator testing apparatus at a set flow rate, examined for penetration with an SMPS, CPC, and DMA given these conditions: differing concentrations of sodium chloride, different engineered particles, and an extended duration of exposure to both sodium chloride and 15-nm titanium dioxide. This study showed that the primary penetrating particle size through an N95 facepiece respirator does increase and shift with increasing concentrations of an aerosol; however, the overall size distribution did not seem to shift much. Penetration decreased as sodium chloride concentration increased. Different nanoparticles had differing primary penetrating particle sizes through the respirator; however, penetration of these particles was similar to one another with the exception of iron oxide which had quite a high penetration percentage. A decrease in N95 respirator performance was observed when exposed to a 1 mg/ml solution of sodium chloride, as penetration increased with prolonged exposure. However, this did not seem to be the case when the respirator was exposed to a 6.67 mg/ml suspension of 15-nm titanium dioxide, as the penetration over the extended period of time was similar to one another.

Chapter II describes results from 197 rural households that were sampled over five continuous days for indoor and outdoor PM10, PM2.5, and endotoxin. Geometric mean indoor concentrations of PM10 and PM2.5 (21.2 πg m-3, 12.2 πg m-3) were larger than outdoor concentrations (19.6 πg m-3, 8.2 πg m-3; p =0.072, p<0.001). While geometric mean endotoxin levels were almost six times larger in outdoor air compared to indoor (1.47 EU m-3, 0.23 EU m-3; p <0.001). Airborne PM10 and endotoxin concentrations in a rural county were elevated compared to those previously reported in certain urban areas. Furthermore, during the harvest season, concentrations of endotoxin in ambient air approached levels that have been shown to cause decreased respiratory function in occupational workers. Chapter III evaluated the effectiveness of using Radiello passive monitors to measure hydrogen sulfide (H2S) in close proximity (<40 m) to a medium sized CAFO. A total of eight passive H2S monitors were deployed 7-14 days around a swine confinement for seven months. Additionally, a separate laboratory study was carried out to determine the monitor's H2S uptake rate. Concentrations of H2S measured near the confinement were varied and ranged from 0.6 to 95 ppb depending on the sampling period and proximity to the lagoon .The uptake rate provided by the supplier (0.096 ng ppb-1 min-1) was significantly larger (p=0.002) than the rate determined experimentally (0.062 ng ppb-1 min-1). In Chapter IV we evaluated the association between residential proximity to swine operations and childhood asthma. A metric was created to determine children's relative environmental exposure to swine CAFOs which incorporated facility size and distance and direction of the CAFO to the home. When controlling for six significant asthma risk factors, children with a larger relative environmental exposure to CAFOs had a significantly increased risk of physician-diagnosed asthma (OR=1.20, p=0.009). In stratified analysis that adjusted for a respiratory infection before the age of two years, the association between relative exposure and childhood asthma was significantly increased in children with a respiratory infection (OR=1.45, p=0.001) but not in children free from respiratory infection (OR=1.12, p=0.355).

The objective of the three studies in this dissertation was to improve methods to prevent musculoskeletal disorders among workers in high-risk occupations. The first two studies, Strain Index (SI) Studies I & II, addressed this problem by better characterizing the performance of a commonly used observational method of estimating potentially hazardous biomechanical exposures, the SI. The SI combines measures of several biomechanical risk factors into a single value (SI score). Strain Index scores are usually categorized into four ordinal SI "risk categories." In Strain Index Study I, multivariate survival analysis models were compared to evaluate the predictive validity of the original SI risk category cut-points to a new set of empirically derived cut-point values among 276 manufacturing workers. The results from this prospective study indicated that the empirically derived cut-points were a better predictor of incident hand-arm symptoms than the original cut-points, especially among women. In Strain Index Study II, Aim 1, exposures to forceful exertions, repetition and non-neutral wrist posture estimated with SI methods were compared to analogous exposures estimated with alternate methods. Statistically significant associations between separate methods designed to assess specific risk factors were observed only for those measuring non-neutral wrist posture. In Aim 2, a multivariate survival analysis model examining associations between incident hand-arm symptoms and biomechanical exposures estimated with the SI was compared to a model examining associations between incident hand-arm symptoms and biomechanical exposures estimated with separate estimates of biomechanical risk factors. Results favored the SI risk category metric to characterize biomechanical exposures compared to separate measures of exposure. he third study, light-weight block (LWB) Intervention Study, was a repeated measures laboratory study of 25 bricklayers performed to estimate the effect of block weight (LWB vs. standard-weight block (SWB)) and course height on low back disorder (LBD) risk factor exposure. Mixed-effect models showed that LWB was associated with reduced exposure for percent time spent in sagittal flexion >30°, lifting rate, LBD risk probability score, and non-dominant upper trapezius muscle activity. Bricklaying at ankle or chest heights was generally associated with higher exposure to risk factors than bricklaying at knuckle height.

In this study, we developed and standardized a sanding method to evaluate the emission of airborne particles from products that contain carbon nanotubes (CNTs) under different conditions, including three types of sandpaper and three sanding disc speed. We also characterized the emission of the airborne particles from one neat epoxy test sample, four CNTs-incorporating test samples with different CNTs loading, and two commercial products. The total number concentration, respirable mass concentration, and particle size number/mass distribution of the emitted particles were calculated and compared, followed by an electron microscopy (EM) analysis. These data suggest that the sanding process can produce substantial quantities of airborne particles. Also, the emission of airborne particles was associated with different test conditions. EM analysis of the airborne particle samples showed embedded CNTs protruding from the outer surface, which was different from CNTs-incorporating bulk material. Our study suggests a potential generation of particles during the life cycle event of sanding. Further studies should be carried out to investigate the potential human health hazard in other life cycle events.

The present study examines the process of emotional labor as performed by customer service employees. This research investigates some of the consequences of performing emotional labor such as emotional exhaustion, affective well-being, and job satisfaction, and attempts to determine which individual and organizational variables play moderating roles in these relationships. One hundred and seventy-six participants from 10 customer service organizations, ranging from retail stores to call centers, completed a 126-item survey. Correlation and regression analyses were conducted to test the proposed hypotheses. Results indicate that gender, emotional intelligence, and autonomy are key moderator variables in the relationship between emotional labor and emotional exhaustion, affective well-being, and job satisfaction. Females are more likely to experience negative consequences when engaging in surface acting. Individuals high in emotional intelligence experienced positive outcomes as emotional labor increased, and the converse is true for those low in emotional intelligence. Autonomy serves to alleviate negative outcomes primarily at the higher levels of emotional labor.

Heat stress is one of many physical agents to which thousands of workers are under constant exposure. Oftentimes it is necessary to work above the WBGT-based heat stress exposure limits. It is therefore important to consider alternative measures that include an exposure time limit to manage the heat stress. Predicted Heat Strain (PHS) (ISO7933) is one of those alternatives. PHS uses both personal factors like height and weight and job factors of environment, metabolic rate and clothing. The purpose of this project is to determine whether the PHS is an adequate method to predict short term exposure limits. The project’s data were taken from a prior experimental study where twelve participants were exposed to five different heat stress levels while over three different clothing ensembles. A total of 15 combinations of clothing and environment were tried. The PHS process was adapted to an Excel function using Visual Basic for Applications (VBA) (called fPHSTre). fPHSTre predicted a rectal temperature (Tre) at the exposure limit using both personal and job factors and then using standard values for personal factors. Based on analysis of variance, the fPHSTre adequately accounted for clothing, specifically evaporative resistance, using either fixed or individual data for predicted Tre on the experimental trials. In general, the PHS model could be used to reliably assess time limiting safe exposures in occupational settings for workers in hot environments.

The purpose of this study was to investigate whether or not differing base metals and filler wires used during welding processes contributed to differing amounts of ultrafine particles (UFP) and nanoparticles being emitted during the welding procedure. The study was also conducted to determine UFP and nanoparticle exposure in the breathing zones of the welders as well as the breathing zones of pipefitters and fire watchers, who commonly sit 6ft behind the welding arc. In order to determine if UFP and NP exposures differed with base metal and filler wire, all welding processes utilized the same welding machine for metal inert gas (MIG), the same wire speed, and the same voltages during each welding process. The only variation in welding procedures were cover gases used, base metals, and filler wires. Measurements gathered during welding procedures were conducted in the breathing zone of the welder and pipefitters consisted of UFP measurements taken by two different condensation particle counters (CPC), which operated in synchrony at the start and cessation of the welding process. NP measurements were taken by a NanoScan Scanning Mobility Particle Sizer (SMPS) and were also placed in the breathing zone of the welder. Lastly, particle characterization measurements for transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were gathered using a filter attached to a high flow pump, which was placed in the breathing zone of the welder. According to the results, base metal and filler wire do emit differing amounts of NP and UFP during the welding processes. Carbon steel emits the highest amount of nanoparticles, while stainless steel emits the second highest amount, and inconel emits the least. The results also concluded that welders are exposed to a greater concentration of nanoparticles and UFPs than those experienced by pipefitters who stand 6ft from the welding arc.

Chlorpyrifos (CPF) is a popular organophosphorus insecticide that is heavily used in the agriculture industry as a means of pest control. Chlorpyrifos is known for its toxic effect to inhibit the enzyme acetylcholinesterase (ACHE) in humans and is widely used in areas of California where the site of application is close to occupied areas, such that exposures to residents and bystanders can occur due to secondary drift. Secondary drift refers to the volatilization of a pesticide from the surface to which it was applied (e.g. soil or plant foliage) and subsequent off-site movement in ambient air. Secondary drift is different from spray drift, which occurs during and very shortly after application. The goal of this thesis is to evaluate existing measurements of secondary drift from ambient air measurements of CPF available from California’s Air Monitoring Network (AMN), in comparison to predictions using a state-of-the-art dispersion model. Pesticide use data were obtained from the California Department of Pesticide Regulation (CDPR) website and was compiled to form scenarios to be modeled and compared against measurements taken throughout the year. Probability distributions for the measured and predicted CPF concentrations resulted in correlations ranging from 3% to 91% depending on the year and modeled scenario. Overall the model overpredicted air concentrations for the modeled scenarios, providing conservative values for risk assessment purposes.