Pesticide use has steadily increased in the United States and throughout the world since the development of more highly effective agrichemicals dating back to World War II. While many of these compounds are considered to have little to no detrimental environmental impact with relatively low toxicity and potential for causing adverse health effects in humans, many recent studies examining the toxicological properties and health outcomes associated with exposure to a variety of pesticides suggest otherwise. In heavily agricultural-based regions, particularly where row crops predominate, large amounts of herbicides and insecticides are used in activities involving pest management annually. The high volume of chemical applications to agricultural fields is cause for concern due their potential for leaching into soil following application events and subsequent transport to water systems. Pesticide-contaminated ground and surface water systems may pose a threat to public health by the presence and persistent elevated concentrations of chemicals found in both public and private drinking water. The herbicides atrazine and glyphosate are and have been the two most heavily applied pesticides in the U.S. Many studies have examined occupational exposures to these compounds and related health outcomes, yet very few have evaluated low-level exposures to more susceptible rural populations. This thesis will examine state-of-the- science behind atrazine and glyphosate, evaluate drinking water quality measurements in relation to herbicide usage estimates in Iowa, and finally, make recommendations for future atrazine and glyphosate exposure assessment studies in rural Iowa populations.

A high-flow (10 L/min) nanoparticle respiratory deposition (NRD) sampler was designed and evaluated to facilitate lower limits of quantification (LOQ) for metal nanoparticles than a low-flow (2.5 L/min) version. The high-flow NRD consists of an inlet, impactor stage, diffusion stage, and a final filter. For the impactor stage, three nozzle sections each containing 12 nozzles were designed from theory to achieve a cut-off diameter (d50) of 300 nm. Various depths of 37-mm-diameter foam cylinders were tested for the diffusion stage to obtain a collection efficiency curve similar to the deposition of nanoparticles in the human respiratory tract, the nanoparticulate matter (NPM) criterion. The objective for the final filter was a collection efficiency of near 100% with minimal pressure drop. The collection efficiencies by size and pressure drop were measured for all components. The impactor stage with one of the nozzle plates had a d50 of 305 nm. The collection efficiency for the foam with a depth of 7 cm adjusted for presence of the impactor was the closest match to the NPM curve with a R2 value of 0.96. Chemical analysis of the metal content for foam media affirmed that the high-flow NRD would require less sampling time to meet LOQs than the 2.5 L/min NRD. The final filter with a modified support pad had a collection efficiency near 100%. The overall pressure drop of the sampler 4.4 kPa (17.5 in. H2O) limits its ability to operate with available belt-mounted personal sampling pumps, although modifications to the sampler design could eliminate this constraint.

Hazardous noise exposures and hearing loss have been documented among farmers and farm workers for many years. However, little is known about the noise exposures during specific agricultural work tasks and their effect on hearing loss. The objective of this dissertation was to assess the effects of specific agricultural tasks on hearing loss and their contribution to total noise exposures. Three studies were conducted to accomplish this objective. The first study examined associations between hearing sensitivity among rural residents (nfarmer = 960, nnon-farmers = 608) and self-reported years of participation in 12 agricultural tasks. Logistic regression analysis was used to examine associations between agricultural activities and hearing loss >25dB. Linear regression analysis was used to examine associations between agricultural tasks and mean decibels of hearing loss. The results indicated farmers have greater hearing loss than non-farmers. However years of participation in specific agricultural tasks was poorly associated with hearing loss. This result suggests that self-reported years engaging in specific agricultural activities may be a poor surrogate for true noise exposure In the second study noise exposures (personal dosimetry) and corresponding task data (direct observation) were collected on 18 grain farms, and mean noise exposures (dBA) were calculated for specific agricultural tasks. Noise exposures ranged from 78.6 dBA to 99.0 dBA across all tasks. The noise exposures for each task varied greatly (large standard deviation and maximum exposure) with most of the variability within the farms. Although specific tasks with intense noise exposures were identified, most comparisons of mean noise exposures from one task to another were not statistically different and intense exposures were present for nearly all tasks. Therefore, controlling noise only for those tasks with the greatest mean noise exposures may not completely eliminate hazardous exposures or the hearing loss risk. For the third study, estimates of 8-hr time-weighted-average (TWA) noise exposures were calculated using time-at-task observations from one population of farmers and prior dosimeter measured mean task-based noise exposures from an independent population of farmers. Additionally, dosimeter measured daily noise exposures from the independent population of farmers were also analyzed to identify significant determinants of noise exposure. Simple linear regression analysis was used to compare estimated and actual dosimeter-measured 8-hr TWA noise exposures. The noise exposure determinants were identified by conducting multivariable linear mixed-effects regression analysis on the one-minute noise measurements from the dosimeter measured daily noise exposures. The results indicated the estimated and measured 8-hr TWA noise exposures varied considerably. Therefore, the estimates were not considered reliable. Furthermore, task, number of noise sources and work area were found to have a statistically significant association with noise exposure. In summary, hearing loss and noise exposures among agricultural populations are complex and cannot be completely explained by examining agricultural tasks only. More detailed evaluations of tasks are needed to increase the understanding of hearing loss and noise exposure in this dynamic work environment.

Detection of airborne influenza virus is needed in order to determine exposure and prevent and control infections. Few researchers have successfully detected airborne influenza virus in environmental settings with current bioaerosol samplers. Therefore, new sampling strategies should be considered to increase the likelihood of detection. This study compared four bioaerosol samplers in collection of airborne influenza virus – the SKC Biosampler, NIOSH Biosampler, Andersen N6 single-stage impactor containing a liquid media, and the newly developed Next Generation Inhalable Aerosol Sampler (NGIAS). Ten 30-minute laboratory trials were completed by aerosolizing active influenza virus (H1N1) in a bioaerosol chamber to compare the ability of four bioaerosol samplers to collect aerosolized virus. Samples were analyzed using RT-qPCR. The mean total virus particles per liter of sampled air (TVP) recovered with the NGIAS was significantly less than that measured by all other samplers (p < 0.001). The TVP recovered with the SKC Biosampler (111.41) and Andersen N6 sampler (102.36) was substantially larger than that recovered with the NIOSH Biosampler (58.59), however the difference in TVP between these samplers was not statistically significant (SKC – NIOSH p-value = 0.187 ; Andersen – NIOSH p-value = 0.297). Our results demonstrated that liquid based bioaerosol samplers recovered more TVP than dry collection samplers. The high flow rate sampler, the Andersen N6, did not collect more TVP, but had a lower limit of detection than other samplers. Furthermore, the SKC Biosampler collected the most TVP. Therefore, future investigators should design a liquid based personal bioaerosol sampler to maximize the likelihood of influenza virus detection.

Workers in the agricultural industry exhibit higher rates of respiratory diseases than workers who are not employed in agriculture. Farm workers may be chronically exposed to organic dust, which is composed of molds, fungi, pesticides, herbicides, animal-derived particles, feed and bedding particles, and endotoxin. Exposure to organic dust has been linked to the development of various respiratory diseases. Research evidence has shown that variability in exposure to inhalable dust is present, and no studies have assessed variability in exposures to inhalable dust specifically among dairy parlor workers. A field-based study was conducted to assess exposures to inhalable dust exposure among individuals working as milkers or pushers on dairy farms in the Midwestern United States. A total of 62 dairy parlor workers participated, and 18 of these workers agreed to participate in repeat measurements and were sampled for two work shifts. Two, bilateral personal breathing zone samples were collected continuously from each worker during one work shift using inhalable samplers, amounting to 160 inhalable dust concentration measurements. The filters were weighed, and the TWA of inhalable airborne dust exposure was calculated for each subject and reported in mg/m3. Statistical analyses were used to examine exposure variability. The results of the statistical analyses did not indicate any statistically significant differences in the means of exposure to inhalable dust between paired sampler groups, with p-values of 0.793, 0.617, and 0.619. An ANOVA analysis of within-worker variance found no statistically significant differences, with p-values of 0.702 and 0.744 for sampler location and sampling day, respectively. Results of the simple linear regression analyses suggested that temperature and humidity levels contribute to less than ten percent of the variability in inhalable dust concentrations. Analyses of the study indicate that exposure to inhalable agricultural dust does not vary significantly (p-value of 0.05 or less) between the means of right-side and left-side collected exposures, as well as from day-to-day, among dairy parlor workers. The geometric mean of 0.54 mg/m3 (GSD 2.5 mg/m3) of the inhalable dust concentrations from this study align with geometric means found in previous studies of inhalable dust concentrations among dairy farm workers. These results support the hypothesis that using a sample of the dairy parlor worker population can provide an accurate estimate of exposure to inhalable agricultural dust among the general dairy farm worker population.

An impinger-based sampling method was designed and evaluated for the collection of airborne cellulose nanocrystals (CNC). Plastic impingers were purchased and a custom nozzle was designed and 3D printed. Collection efficiency by particle size was compared to commercially available impingers. Collection efficiency (CE) was then adjusted theoretically for an impactor that would be used in a field setting to remove particles larger than 300 nm. Adjusted CE was compared to the nanoparticulate matter (NPM) criterion model, which mimics nanoparticle deposition in the human respiratory system. The impinger method was then used to collect rhodamine-tagged CNC to determine if it could collect a concentration of CNC that agreed with the known aerosolized concentration when analyzed with spectroscopy/spectrophotometry. The plastic impinger method had a greater collection efficiency for relevant particle sizes than the commercially available impingers tested. After adjusting for the impactor, the impinger method agreed with the NPM curve for particles ranging from 45-600 nm (R2=0.94). Concentrations of rhodamine-tagged CNC collected with the impinger method did not agree with the concentrations measured by the reference instrument, however this was likely due to issues with the batch of CNC used. The impinger method can be used to collect other nanoparticles, but analysis methods that do not rely on using tagged CNC must be developed to mate the preferred analysis method with sampling.

Characterizing airborne influenza virus exposure is important for infection prevention and exposure control in health care and public settings. Detecting airborne influenza virus is important in assessing infection risk. The virus must also be protected from deterioration during aerosol sampling and long term storage. RNA preservation buffers (RNAPBs) may stabilize influenza virus after sampling and during storage. Bioaerosol samplers are used to collect airborne influenza virus, and many different types of samplers are available. The objectives of this experiment were to: 1) compare influenza virus concentrations across bioaerosol samplers; 2) compare the efficacy of RNAPB over Hanks Balanced Salt Solution (HBSS) as a sample collection media; and 3) determine whether RNAPB stabilizes viral particles stored over time. In this experiment we aerosolized active influenza virus (H1N1) in a bioaerosol chamber and compared sampling efficiencies using two different samplers: the SKC Biosampler and NIOSH Biosampler, and two different medias: Hanks Balanced Salt Solution (HBSS) and an RNAPB. Ten 15-minute experimental trials were completed. We also compared HBSS and RNAPB in terms of the maintenance of virus RNA integrity during storage at room temperatures. Samples were stored at room temperature for 1, 4, 7, and 14 days. Virus concentrations were measured and compared at each time point. Significant differences were found between sampler and media type - the SKC Biosampler collected a higher concentration of virus than the NIOSH Biosampler, and HBSS collected a higher concentration of virus than RNAPB. In storage at room temperature conditions, RNAPB maintained virus in concentrations significantly greater than in HBSS. The results of this experiment indicates that the SKC Biosampler should be used to characterize airborne influenza and that RNAPB should not be used as a sampling media but can be used to preserve samples if needed.

Background: Endotoxin is a lipopolysaccharide located on the outer membrane of the cell wall of Gram-negative bacteria that is widespread in the environment. Although domestic endotoxin has been found to be associated with asthma and wheeze, its association with chronic obstructive pulmonary disease (COPD) is unclear. It is also unknown how environmental exposures influence the relationship between endotoxin and asthma and very few studies have investigated the effectiveness of interventions in reducing endotoxin in the homes of people with asthma. Goals: The goals of this dissertation were to examine 1) the association of house dust endotoxin with chronic bronchitis or emphysema, two phenotypes of COPD, 2) the influence on the relationship between endotoxin and asthma outcomes of environmental factors such as exposure to dog and cat in homes, climate regions, as well as co-exposure to ambient air pollution, and 3) the effectiveness of an environmental intervention in reducing home endotoxin and asthma symptoms in rural Iowa children with asthma. Methods: For the first two goals of this dissertation, data from the 2005-2006 National Health and Nutrition Examination Survey (NHANES) was used. Dust sampled from the bedroom floor and bedding of 6,963 children and adult participants was evaluated for endotoxin at the University of Iowa Pulmonary Toxicology facility using a kinetic chromogenic Limulus amebocyte lysate assay. Data on asthma outcomes and chronic bronchitis or emphysema (CBE) was collected using questionnaires. Home exposure to dog and cat was considered by pet ownership and levels of dog (Canis familiaris 1) and cat (Feline domesticus 1) allergens in house dust. Annual average particulate matter ≤2.5 µm (PM2.5), ozone (O3), and nitrogen dioxide (NO2) concentrations at participants’ residential location were estimated using the Community Multiscale Air Quality (CMAQ) and Downscaler (DS) models. In the third goal, data from the Louisa Environmental Intervention Project (LEIP) study which included schoolchildren 5-14 years-old with active asthma from Louisa and Keokuk counties in rural Iowa was analyzed. The households were block-randomized to receive extensive (education + professional cleaning) or educational intervention. Environmental sampling and questionnaire administration were done at baseline and during three follow-up visits. Results: In the NHANES, the median concentration of endotoxin in house dust was 16.2 EU/mg. In adjusted analysis, house dust endotoxin (log10-endotoxin) was associated with increased odds of CBE diagnosis (OR: 1.27, 95% CI: 1.00-1.61) and chronic bronchitis symptoms (OR: 1.78, 95% CI: 1.01-3.12). Sensitization to inhalant allergens modified the relationship between log10-endotoxin and CBE diagnosis (P(interaction)=0.001), with stronger associations observed in sensitized participants (OR: 2.46, 95% CI: 1.72-3.50). The association of endotoxin with asthma outcomes was different with climate regions of the U.S. Endotoxin was associated with higher prevalence of wheeze outcomes in the past 12 months in subarctic/very cold/cold regions (OR: 1.48, 95% CI:1.19-1.85) and in hot-humid regions (OR: 1.66, 95% CI:1.04-2.65). In hot-humid regions, endotoxin was positively associated with current asthma (OR: 1.56, 95% CI:1.11-2.18), but negatively with sensitization to any inhalant allergens (OR: 0.83, 95% CI:0.74-0.92). Exposure to dog and cat allergens enhanced endotoxin association with current asthma (OR: 2.00, 95% CI: 1.04-3.83, P(interaction)=0.012) and wheeze in the past 12 months (OR: 1.88, 95% CI: 1.32-2.66, P(interaction)=0.016). House dust endotoxin co-exposure with PM2.5 (CMAQ) was synergistically associated with emergency room visits for asthma in the past 12 months (OR: 5.01, 95% CI: 2.54-9.87) in general. In children, a synergistic association was found for co-exposure to house dust endotoxin and NO2 with the outcome (OR: 3.45, 95% CI: 1.65-7.18). In LEIP, 104 asthmatic children from 89 homes were included in the study. In the main analysis, extensive compared to the educational intervention was associated with decreased endotoxin load in farm homes (P-value of main effect for intervention <0.0001) and with less frequent nighttime asthma symptoms (Intervention x visit interaction P-value = 0.044). In exploratory analysis, endotoxin load reduction from baseline was associated with less daytime wheeze (OR: 0.59, 95%CI: 0.38-0.91) and daytime cough (OR: 0.62, 95% CI: 0.40-0.97). Conclusions: House dust endotoxin is associated with obstructive pulmonary diseases. The association of endotoxin with asthma outcomes is stronger in cold regions of the U.S. and is enhanced by exposure to pet allergens and co-exposure to ambient air pollutants such as PM2.5 and NO2 in children. The LEIP study demonstrated that extensive cleaning interventions can be effective at reducing endotoxin in the homes children with asthma and can alleviate their symptoms.

How do we shape our safety destiny? It is within the limits or our own making, that is, our capability. But, how do we know it is on the right track? In other words, how do we take the pulse? These questions set the context and scope of the research in which a number of key issues related to capability building and evaluation were addressed. In recent years, the approach of capability development has been widely researched by economists, organizational psychologists and management theorists. Unfortunately, because of its complex nature, the assessment of capability in professional context has not been properly addressed in the literature. The problem is two-fold. First, is criticality, or more accurately the lack of understanding about what capabilities are critical to our future success. The second one is concerned with the evaluative aspects of capability development. Using safety management as a study platform, this research introduced a contingency model of “strategic capability development” (SCD) as a plausible alternative to some of the well-established approaches. To address the evaluation issues, an innovative method for assessing capability maturity was constructed. The key variables were based on people’s pro-activeness and their self-efficacy beliefs. Through meta-analysis, a set of critical capabilities or indicators was identified and used as the key variables for designing the survey instrument, the Safety Management Efficacy Scale (SMES). These variables included goal-setting, risk management, safety training, risk communication, and operation/administration capabilities. Hypotheses regarding the interactive effects of each of these critical capabilities were then derived and tested. The results suggest that a high degree of coherency among the key variables does exit. There is a positive and significant association between critical capabilities and goal-setting capability. The positive effects of risk management capability on safety pro-activeness are strong. In regards to how goal-setting capability influences pro-activeness, no conclusion can be drawn. Having taking the pulse, the capability maturity profile of the safety profession is examined. The proposed SCD framework and SMES instrument together provide a point of departure for conducting similar research, including but not limited to human resources development, people capability maturity assessment, training/curriculum development, and performance evaluation. / Doctor of Philosophy (PhD

The study was conducted to evaluate the use and perceived effectiveness of occupational safety and health consultative services among Oregon corporations. The three types of consultative services examined: workers' compensation insurance; private; and Oregon Occupational Safety and Health. The research examined if corporations, categorized by corporation size, within the four high-risk industry classes used each of the three types of consultative services. The four high-risk industry classes included: agriculture; construction; manufacturing; and wood products. Based on the results of the study, fewer than one-half of the respondents reported they had used consultative services; however, two out of three respondents indicated they were aware that consultative services were available. Of the three types of consultative services, workers' compensation insurance consultative services were used most frequently. In contrast, private consultative services were used least frequently even though respondents were most aware of the availability of the services. Overall, small corporations, primarily from the agriculture industry class, used consultative services the least whereas large corporations were most likely to use consultative services. Almost half of all respondents, who were aware of the availability of the consultative services and indicated that they had not used or would not use these services in the future, reported that they believed these services were unnecessary for their corporation. In addition, over half of the respondents cited cost as a prohibitive factor in requesting private consultative services. Among those respondents who implemented the recommendations of occupational safety and health consultants, over 84 percent of the respondents felt that the recommendations were either very effective or somewhat effective for all three types of consultative services. Although this percentage of perceived effectiveness was high, the percentage of respondents who reported that consultative services were instrumental in loss reduction was considerably lower than the perceived effectiveness. This finding indicates that respondents' perceived effectiveness of occupational safety and health consultative services include more than loss reduction elements. Future studies need to discern what these additional elements include. / Graduation date: 2000