Browsing by Subject "Exposure"
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Item Children’s willingness to accept labels in two languages: the role of exposure(2015-12) Rojo, Dolly P.; Echols, Catharine H.; Booth, Amy E; Bannard, ColinDespite the increasing number of bilingual education programs in the US, the topic of children’s willingness to accept and learn new vocabulary from non-native speakers has been understudied. The present study focuses on the role of exposure to a non-English language, by investigating how varying amounts and sources of exposure play a role in children’s openness to accepting labels in Spanish. Ninety-eight 4- to 6-year old participants of varying language backgrounds were presented with novel object labels in Spanish and English, and were asked to endorse either or both labels. Children with large amounts of exposure to, but not fluent in, Spanish were more likely than minimally exposed monolingual children to endorse both the English and Spanish label, and importantly, did not differ from bilingual children. Monolingual children with minimal exposure to Spanish were the least likely of these three groups to endorse non-native labels. Language Awareness is also considered as a factor that may contribute to children’s willingness to endorse native and non-native labels.Item Enhancing exposure therapy for specific phobias using a pre-treatment fear priming task(2011-05) York, Jamie Lauren; Telch, Michael JosephRecent animal and human research suggest that a behavioral prime before extinction training lessens the spontaneous recovery of learned fear. These findings would have large ranging implications, if they could be applied to the treatment of specific phobias in which spontaneous recovery is often problematic. The present study examined the effects of a behavioral prime paired with exposure therapy versus exposure therapy alone on snake and spider phobics return of fear at one-month follow-up. The findings did not support the proposed hypothesis that those in the primed group would show a significant lessening in return of fear. The study findings do not support the current research, but there are a number of steps that may be taken in the future to gain more objective measurements that may lead to hypothesis support.Item Exposure to hazardous air pollutants in homes(2010-05) Hun, Diana Esther; Corsi, Richard L.; Siegel, Jeffrey A.; Morandi, Maria T.; Novoselac, Atila; Paterson, Robert G.Prior studies have found that human exposure to hazardous air pollutants (HAPs) occurs in homes; however, the depth of these assessments was limited by the extent of the analyzed data. The present Ph.D. dissertation focused on air contaminants of concern in residential buildings, the possible sources of these pollutants, and population subgroups with greater contaminant risk. This research also evaluated the effects of building characteristics and household activity patterns on indoor pollution and risk levels. To this end, an in-depth analysis was performed of data from the Relationships of Indoor, Outdoor and Personal Air (RIOPA) study, one of the most comprehensive exposure assessments to date. Using personal concentrations from the RIOPA study, a cancer risk assessment was performed to identify both important pollutants and populations at higher risk. The analyzed compounds were acetaldehyde, benzene, chloroform, carbon tetrachloride, p-dichlorobenzene (p-DCB), ethylbenzene, formaldehyde, methylene chloride, methyl tert-butyl ether (MTBE), styrene, trichloroethylene and tetrachloroethylene. Results indicate that Hispanics and non-Hispanic whites had median cumulative cancer risks (CCR) of 520×10-6 and 440×10-6, respectively, for which the main contributors were formaldehyde, p-DCB, acetaldehyde, chloroform and benzene. Statistically significant differences in CCR between and within Hispanic and whites were primarily due to exposures to p-DCB. Exposure to formaldehyde was further investigated because this compound was the largest contributor to CCR for 69% of Hispanics and 88% of whites, and because most participants had similar cancer risks from these exposures (median = 260×10-6, coefficient of variance = 28%). Results suggest that the U.S. population may be experiencing chronic exposures because of long-term formaldehyde emissions from pressed-wood materials bound with urea-formaldehyde resins. Source removal may be the most effective way to decrease these chronic exposures. Benzene was also examined further because it is a known human carcinogen. Results show that indoor benzene concentrations increased as the proximity of parked vehicles decreased. Residing in a home with an attached garage could lead to exposures to benzene ten times higher than while commuting in a car in heavy traffic, and with mean excess cancers of 17×10-6. Detached garages could reduce health risks from exposure to benzene and other gasoline-related pollutants.Item Fruit and vegetable exposure in children is linked to the selection of a wider variety of healthy foods at school(2011-12) Korinek, Elizabeth Victoria; Bartholomew, John B.; Jowers, Esbelle M.Background: The relationship between fruit and vegetable (FV) exposure, preference, and consumption among children has been a targeted topic of study due to the increasing prevalence of childhood obesity. The purpose of this study was to examine FV home exposure in elementary children and the selection of both fruits and vegetables and less familiar lunch entrées at school. Design: Cross-sectional data on 3rd, 4th, and 5th grade students (N=59) from an elementary school in central Texas. Methods: Home and school FV exposure was collected via self-report using a six-item questionnaire. Students were placed into high and low groups for 1) the variety of FV offered at home, and 2) the variety of FV eaten at home. Absolute and relative ratings of eight lunch entrées were collected through taste-tests conducted at school. Results: Differences in the consumption of FV at school and the selection of lunch entrées between high and low groups were analyzed using Mann-Whitney U independent non-parametric tests. Results indicated that the distribution of consumption at school differed across high and low groups for parental offering of FV for: oranges (z=2.16, p<0.05), cucumber (z=2.44, p<0.05), pineapple (z=3.41, p=0.001), mandarin oranges (z=2.93, p<0.01), tomato (z=3.14, p<0.01), and broccoli (z=3.26, p=0.001). The distribution of consumption at school across high and low groups for the eating FV at home was significant for 10 out of the 11 FV items: oranges (z=2.24, p<0.05), cucumber (z=2.64, p<0.01), pineapple (z=4.19, p<.001), mandarin oranges (z=3.06, p<0.01), tomatoes (z=3.47, p=0.001), bell pepper (z=2.25, p<0.05), broccoli (z=4.00, p<0.001), melon (z=3.06, p<0.01), apples (z=2.79, p<0.01), and zucchini (z=2.27, p<0.05) Likewise, significant differences between high and low groups for parental offering of FV were found for the selection of the chef salad (z=2.546, p<0.05), the Greek salad (z=2.091, p<0.05), and the veggie humus plate (z=2.104, p<0.05). Absolute and relative ratings of eight lunch entrées are also reported. Conclusions: Children who are more frequently exposed to FV at home consume a wider variety FV at school and are more likely to select healthy, less familiar entrées at school lunch.Item Inhalation exposures during cleaning activities(2013-05) Earnest, Clive Matthew, Jr.; Corsi, Richard L.Studies show that the use of cleaning products is related to adverse respiratory health effects ranging from irritation to asthma. Yet exposure to these chemicals is poorly understood. This dissertation summarizes the current state of knowledge of inhalation exposure to toxic chemicals in consumer cleaning products. An improved two-zone model that treats personal air space as distinct from bulk room air is presented. The model accounts for air exchange between the two zones, dynamic source characteristics (i.e., the time-varying liquid concentrations and emission rates of pollutants within a mixture), and the characteristics of chemical use (e.g., how frequently a cleaning chemical is applied to a new area). To assess exposure to cleaning products and validate the improved two-zone model twenty-three experiments, encompassing six cleaning scenarios, were completed in an environmentally-controlled chamber with a thermal mannequin. Then, the model was used to predict exposure for four hypothetical cleaning scenarios and compared against other models. The model's applicability is restricted by limited data available for parameterization. At low air exchange rates gas-phase experimental results show concentrations in the breathing-zone of the mannequin exceeded concentrations predicted by the well-mixed model by factors up to 2.1. Breathing-zone concentrations also exceed those measured at centralized room monitors by factors up to 6.1. Thus, studies that use the centralized room monitors or the well-mixed model as a surrogate for breathing-zone concentrations could potentially underpredict exposure at low air exchange rates. The two-zone model provides the best prediction of exposure to cleaning tasks, at low air exchange rates. The next best model is the well-mixed model with an exponentially decreasing emission rate, followed by the well-mixed model with a constant emission rate. At high air exchange rates the well-mixed assumption appears to be valid. The inner-zonal volume and inter-zonal air exchange were independent of fresh air ventilation rate. But both were dependant on the mannequin's body position, with standing having the highest inner-zonal volume and lowest intra-zonal air exchange rate of the three body positions investigates (standing, bent over 45°, and hands and knees).Item Particulate reactive oxygen species in indoor and outdoor environments : prevalence and health effects(2015-05) Khurshid, Shahana Sarfraz; Kinney, Kerry A.; Siegel, Jeffrey A; Corsi, Richard; Novoselac, Atila; Wells, J. RaymondReactive Oxygen Species (ROS) are an important class of air pollutants generated from photochemical and ozone-initiated reactions in indoor and outdoor environments. Despite the fact that Americans spend nearly 90% of their time inside buildings and extended exposures to ROS can occur in indoor environments, ROS has received very little attention as an indoor pollutant. This is one of the first research studies to measure the concentration of particulate ROS (on PM [subscript 2.5] and TSP) in indoor environments. A significant fraction of indoor particulate ROS was found to exist on PM [subscript 2.5] (58±10%) which is important from a health perspective since PM [subscript 2.5] can carry ROS deep into the lungs. The indoor concentrations of ROS on PM [subscript 2.5] sampled in residential and commercial buildings were not significantly different from the outdoor concentrations. This result is intriguing because it implies that generation of ROS inside buildings and/or transport of outdoor ROS and precursors of ROS into buildings are important processes and can be as significant as ROS generation in outdoor environments. Controlled studies show that when outdoor ozone concentrations are relatively low, indoor concentrations of ROS are dominated by indoor sources of ROS rather than outdoor sources of ROS. However, when outdoor ozone concentrations are relatively high, indoor and outdoor sources of ROS contribute almost equally to the indoor concentration of ROS. This study is also one of the first to assess seasonal variations in outdoor particulate ROS concentrations. Ambient sampling conducted over an 11-month period indicates that outdoor particulate ROS concentrations are influenced by the ozone concentration, solar radiation intensity and temperature. In order to understand the potential health effects of exposure to ROS, an in vitro exposure system of lung epithelial cells and differentiated lung tissue was also utilized. Results from these experiments indicate that exposure to products of limonene ozonolysis (which include ROS) can lead to a greater inflammatory response than exposure to either ozone or limonene. This highlights the need to include biologically relevant pollutants, such as ROS, in indoor air quality studies. Further work is warranted to better understand the parameters that drive indoor particulate ROS concentrations.