Determinants of Atrazine Contamination in the Homes of Commercial Pesticide Applicators Across Time
The University of Iowa, College of Public Health, Department of Occupational and Environmental Health, Iowa City, Iowa, USA.Journal of Occupational and Environmental Hygiene (Impact Factor: 1.17). 05/2012; 9(5):289-97. DOI: 10.1080/15459624.2012.668658
Twenty-nine commercial pesticide applicator households in eastern Iowa were enrolled to investigate in-home contamination of atrazine, the most commonly used corn herbicide in the Unites States. From each home, four vacuum dust samples were collected during atrazine application season (Visit 1) and again 6 months later during winter months (Visit 2). Samples were taken from the following locations: primary entryway for pesticide applicator, living room, master bedroom, and kitchen. The applicator completed an atrazine handling log and household questionnaire with spouse. Of the 230 dust samples, only 2 were below the level of detection, 2 ng of atrazine per gram (ng/g) of fine dust (dust particle size 5-150 μm). Dust levels were standardized to chemical loading. During application season the entryway (2.68 ng/cm(2)) and kitchen (0.47 ng/cm(2)) had the highest geometric mean atrazine chemical loading. The entryway chemical loading during Visit 2 was the second highest aggregate (0.55 ng/cm(2)). Aggregate concentrations were significantly higher at Visit 1 compared with Visit 2 when paired by location (p≤0.02). Analysis showed that job (application, mixing/loading, or both) was not associated with in-home atrazine contamination. Linear regression showed a strong positive association between atrazine handling (number of acres applied with atrazine, number of days atrazine handled, and pounds of atrazine handled) and aggregate dust chemical loading from both visits (p = 0.06, 0.03, and 0.10, respectively). Frequency of vacuuming was inversely associated with Visit 2 concentrations (p = 0.10) and showed a weaker association with Visit 1 (p = 0.30). Removing shoes outside the home was associated with lower atrazine chemical loading (p = 0.03), and applicators changing work clothes in the master bedroom had significantly increased atrazine chemical loading in master bedrooms (p = 0.01). Changes in hygiene practices for commercial pesticide applicators could significantly reduce atrazine and, likely, other pesticide contaminations in the home.
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ABSTRACT: Purpose: To assess occupational inhalation exposure to the herbicide atrazine during pesticide application in a developing country. Methods: Personal air samples were collected during atrazine application using a personal sampling pump equipped with an OSHA Versatile Sampler (OVS-2) sorbent tube. Samples were collected from 24 pesticide applicators in Honduras. Application was observed during sampling, and a survey was completed in the home. Results: Fourteen of the 24 participants used pump backpack sprayers to apply atrazine and 10 used tractor/boom systems. Despite applying about 15 times as much atrazine, the tractor/boom participants (11.5 μg/m(3)) had only slightly higher (not statistically significant) time-weighted averages (TWA) than participants using backpack sprayers (9.6 μg/m(3)). Within the backpack sprayer group, those that used a cone spray nozzle (11.54 μg/m(3)) had nearly double the TWA than applicators using a flat spray nozzle (5.98 μg/m(3); P = 0.04). In the tractor/boom group, the participants that rode on the boom or the back of the tractor monitoring nozzles (15.0 μg/m(3)) had almost double the average TWA than tractor drivers (8.0 μg/m(3); P = 0.097). Conclusions: Since tractor/boom pesticide application decreases the number of man-hours required to apply pesticides, and does not increase inhalation exposure significantly, it decreases the overall population occupational exposure. Monitoring nozzles on booms from a distance rather than on the back of a tractor or boom may decrease or eliminate inhalation exposure. Use of flat spray nozzles for herbicide application among pump backpack sprayers may reduce their inhalation exposure.International Archives of Occupational and Environmental Health 05/2012; 86(4). DOI:10.1007/s00420-012-0776-2 · 2.20 Impact Factor
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ABSTRACT: Web services usually compose to workflows to satisfy complex demands. End-to-end execution time is widely seen as a key quality metric of web service workflows. That will be affected by many factors. This paper focuses on impacts of an important factor -- scheduling algorithm in services -- on collective end-to-end time characteristics of a set of web service workflows. We develop a novel simulator, in which workflows are simulated to execute. Impacts of different scheduling algorithms are evaluated through comparing simulation results. Simulation results indicate that maximal and average end-toend execution time of most workflows when using "earliest deadline first" (EDF) scheduling algorithm in services is significant shorter than that when using widely used "first in, first out" (FIFO) scheduling algorithm.Services (SERVICES), 2013 IEEE Ninth World Congress on; 01/2013
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ABSTRACT: Polychlorinated biphenyl (PCB) production ceased in the U.S. over 30 years ago, but these persistent chemicals remain ubiquitous contaminants. Here, we evaluate potential determinants of PCB levels in dust from California homes including characteristics of the residence as well as the residents' habits and occupations. Dust was collected from 415 households as part of a large case-control study (the Northern California Childhood Leukaemia Study), using a high-volume small surface sampler. Dust concentrations of 6 PCBs (PCB-105, PCB-118, PCB-138, PCB-153, PCB-170, and PCB-180) were measured using gas chromatography-mass spectrometry. Individual PCB detection rates ranged from 9% to 54% with PCB concentrations ranging from below detection (1 or 2 ng g−1) to 270 ng g−1 and PCB loadings ranging from below detection to 960 ng m−2. Multivariable linear and logistic regression models were used to identify potential determinants of residential PCB contamination based on in-home interviews and residential geographic locations. We observed that residences built prior to 1980 had higher odds of PCB detection and higher PCB loadings than more recently constructed homes. Households where residents typically did not remove their shoes had higher PCB dust loadings than households where residents did. PCBs were less likely to be detected in carpet dust from households that had frequently vacuumed or replaced carpets compared to other households. Since we used a cross-sectional dust sampling protocol and report significant, but modest, effects of these determinants on levels of PCBs in residential dust, our results should be interpreted with caution. Longitudinal studies to determine optimal strategies for reducing PCBs in homes are warranted.Environmental Sciences: Processes and Impacts 01/2013; 15(2):339-346. DOI:10.1039/C2EM30721A · 2.17 Impact Factor
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