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2001 Progress Report: Pesticide Exposure Pathways Research Project
EPA Grant Number: R826886C004Subproject: this is subproject number 004 , established and managed by the Center Director under grant R826886
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: University of Washington
Center Director: Faustman, Elaine
Title: Pesticide Exposure Pathways Research Project
Investigators: Faustman, Elaine
Institution: University of Washington
EPA Project Officer: Fields, Nigel
Project Period: August 1, 1998 through December 31, 2003
Project Period Covered by this Report: August 1, 2000 through July 31,2001
Project Amount: Refer to main center abstract for funding details.
RFA: Centers for Children's Environmental Health and Disease Prevention Research (1998)
Research Category: Children's Health , Health Effects
Description:
Objective:The long-term objectives of this project are to prioritize efforts to prevent childhood pesticide-associated illness, estimate the relative contribution of major pesticide exposure pathways to children’s exposure, expedite the development of effective intervention strategies, and develop model intervention strategies for reducing pesticide exposure.
The specific aims are to:
- Quantify spatial and temporal variability in pesticide residues in and around residences of farmworker children, including quantifying the impact of spray drift during and after pesticide application;
- Characterize child activities during periods of residential pesticide contamination and during periods when children have the opportunity to enter recently pesticide-treated areas;
- Quantify transfer of pesticides from workplace to residence by farmworkers and subsequent exposure of farmworker children;
- Develop a source attribution model for the major pesticide exposure pathways based on environmental measurements, child activities, and biological measures of exposure;
- Develop specific recommendations for interventions designed to reduce pesticide exposure in farmworker children.
Our work has focused on the first three specific aims during the past year. Work related to the take home exposure pathway (Specific Aim #3) has been conducted in collaboration with the Community Intervention Project and the Exposure Assessment Core. Cynthia Curl, now a Research Scientist in our group, completed her M.S. thesis on this topic in August 2000. She is also the principal author of a submitted manuscript that demonstrates a strong association between pesticide concentrations in vehicle dust and house dust. These findings appear to confirm the hypothesis, put forward by a member of our Community Advisory Board, that the vehicle is an important point along the take home exposure pathway. Additionally, the recent publication by our group (Lu, et al., 2000) provides new evidence of exposure pathways.
Progress has been made in three areas of Aims #1 and #2: (1) development of a LIght Detection And Ranging (LIDAR) system for evaluating spray drift; (2) acquisition and testing of global positioning system (GPS) units for tracking children’s behavior; and (3) design of a field sampling study to quantify pesticide drift. Each of these areas is discussed in detail below. Additionally, the Department of Environmental Health Laboratory has completed development of new methods for analysis of pesticides in house dust. A manuscript reporting these methods has been accepted for publication (Moate, et al., 2002).
LIDAR Development
As reported last year, field testing of the LRS-50 LIDAR system for spray drift monitoring indicated that this system had a useful range of < 1 km. Although spray aerosols were observed, the range was considered too limited since the study area of interest typically is 3 to 5 km. We decided it was necessary to modify the LIDAR system to increase the range and detection capability. The primary way to increase the LIDAR range is to increase the laser power in the transmitted pulse. However, the LRS-50 was designed to operate in the near-infrared region at a wavelength of 808 nm, and eye safety limits preclude increasing the laser power at this wavelength to any reasonable degree. Therefore the LIDAR transmitter system was changed to operate in the near-UV region at 355 nm, where a significant increase in power could be obtained while maintaining eye-safe operation. An additional benefit of this change is that aerosol backscatter should be larger (about 5 times). We have redesigned the LRS-50 instrument to fit it with a more powerful compact neodymium-doped yttrium aluminum garnet (Nd:YAG) laser operating at 355 nm (266, 532, or 1064 nm outputs also are available). The laser produces pulses with about 1 megawatt of peak power (8 mJ in 5 ns) into the transmitter. In comparison the diode laser system used previously produced about 3 kW of peak power. The transmitter expands and collimates the outgoing beam with a Galilean lens system to maintain eye-safe conditions. All the transmitter and receiver optics were replaced with UV grade acrylic or fused silica lenses to maintain high UV throughput. Internal mirrors were replaced with mirrors having a UV enhanced coating. In addition, a 10 nm narrow bandpass interference filter, centered on the laser wavelength, was added to reduce background daylight and allow the system to operate equally well during day or night conditions. The instrument currently is undergoing final operational testing and alignment. This instrument was taken to eastern Washington in May and June and used to monitor orchard airblast applications. This field trial served to identify operational aspects of the instrument that can be improved through hardware and software modifications. These modifications are underway and should be completed early in Year 4. We plan to conduct further field evaluations with the instrument in Year 4. Ming Tsai, formerly a Ph.D. candidate in the Department of Civil Engineering, has enrolled as a Ph.D. student in Environmental Health. He is working with Dr. Yost to develop the hardware and software components of the LIDAR instrument.
Global Positioning System Component
Characterizing the temporal-spatial path traveled by children is key to understanding child pesticide exposure. In Year 1 feasibility studies were conducted with commercially available GPS units. In Year 2 we purchased three customized GPS units from Entertech Corporation. Kai Elgethun, a Ph.D. student working on this project, traveled to Entertech in July 2000 to pick up the instruments and receive detailed instructions on the hardware and software operations. The new instrument is a differential signal-corrected global positioning systems personal acquisition logger (GPS-PAL) designed for human exposure assessment studies. We aim to use the GPS-PAL to track children’s time-location near pesticide-treated land. The GPS-PAL is high resolution (3.2 m root mean square error), data logging, lightweight (200 g), and can record 25 hours of 5 second interval data. Latitude/longitude data are downloaded onto a PC, and the data are post-processed to increase resolution using differential signal data obtained online from a U.S. Coast Guard reference station. Once data are post-processed, the resulting locations can be mapped onto U.S. Geological Survey (USGS) digital orthophoto quad (DOQ) maps in geographic information systems (GIS) software (ArcView 3.2, ESRI, Redlands, CA). DOQ maps have a resolution of 1 meter. Adding this error to the GPS-PAL error yielded an overall positioning error of £ 4.2 meters. This resolution, in combination with a 5 second sampling interval, was adequate to determine whether a child was indoors or outdoors, or on one side of a fence or the other. GPS-PALs received signals reliably through clothing, inside wood-frame buildings, and proximal to both wood-frame and concrete/steel-frame buildings. Loss of reception proximal to potential interferences (electric power transformers, radio transmitters, cell phones) was quantified. Eleven children aged 3-7 years in the Seattle area wore GPS-PALs carried in specially designed clothing for 12 hours. This pilot study identified compliance and function problems that were corrected. Clothing was adjusted to be more comfortable, cable connectors re-fitted to be more secure, and startup procedures modified to expedite initial reception. We believe the GPS-PAL is significantly more accurate than parent-reported data on child time-location. We plan to test this hypothesis among farmworker families in central Washington and to correlate time-location with environmental pesticide samples and urinary pesticide metabolite samples in Year 4.
Drift Sampling Component
Drift sampling is planned in conjunction with the LIDAR studies to test and refine the dispersion models that are under development, and to calibrate the LIDAR measurements. In Year 2 we identified a major industry report produced by the Spray Drift Task Force, which has been working with the U.S. Environmental Protection Agency (EPA) to establish a scientific basis for human ecological risk assessments related to agricultural spraying. We are using material from this report in the development of our drift sampling strategies. We have purchased 10 high volume air samplers for use in field studies and have developed new deposition samplers for use in the orchard environment. These instruments were field tested successfully in May and June 2001. These sampling instruments will be used to characterize spray drift in our Year 4 studies.
Human Subjects Procedures
The procedures followed in this study have been reviewed by the University of Washington Human Subjects Division (Application No. 98-6567-C04) and are approved through June 13, 2002. All investigators have completed required human subjects training at the University of Washington.
Journal Articles on this Report: 8 Displayed | Download in RIS Format
| Other subproject views: | All 15 publications | 9 publications in selected types | All 9 journal articles |
| Other center views: | All 83 publications | 51 publications in selected types | All 47 journal articles |
| Type | Citation | ||
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Curl CL, Fenske RA, Kissel JC, Shirai JH, Moate TW, Griffith W, Coronado G, Thompson B. Evaluation of take-home organophosphorus pesticide exposure among agricultural workers and their children. Environmental Health Perspectives 2002;110(12):A787-A792. |
R826886C003 (2001) R826886C003 (2002) R826886C004 (2001) R826886C004 (2002) R831709 (2005) |
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Fenske RA, Kissel JC, Lu C, Kalman DA, Simcox NJ, Allen EH, Keifer MC. Biologically based pesticide dose estimates for children in an agricultural community. Environmental Health Perspectives 2000;108(6):515-520. |
R826886C004 (2001) R831709 (2005) |
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Fenske RA, Lu C, Simcox NJ, Loewenherz C, Touchstone J, Moate TF, Allen EH, Kissel JC. Strategies for assessing children’s organophosphorus pesticide exposures in agricultural communities. Journal of Exposure Analysis and Environmental Epidemiology 2000;10(6 Suppl 2):662-671. |
R826886C004 (2001) R825171 (2000) R831709 (2005) |
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Lu C, Fenske RA. Dermal transfer of chlorpyrifos residues from residential surfaces: comparison of hand press, hand drag, wipe, and polyurethane foam roller measurements after broadcast and aerosol pesticide applications. Environmental Health Perspectives 1999;107(6):463-467. |
R826886C004 (2001) R831709 (2005) |
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Lu C, Fenske RA, Simcox NJ, Kalman D. Pesticide exposure of children in an agricultural community: evidence of household proximity to farmland and take home exposure pathways. Environmental Research 2000;84(3):290-302. |
R826886C004 (2001) R831709 (2005) |
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Moate TF, Lu C, Fenske RA, Hahne RMA, Kalman DA. Improved cleanup and determination of dialkyl phosphates in the urine of children exposed to organophosphorus insecticides. Journal of Analytical Toxicology 1999;23(4):230-236. |
R826886C004 (2001) R825171 (1999) R825171 (2000) R831709 (2005) |
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Moate TF, Furia M, Curl C, Muniz JF, Yu J, Fenske RA. Size exclusion chromatographic cleanup for GC/MS determination of organophosphorus pesticide residues in household and vehicle dust. Journal of AOAC International 2002;85(1):36-43. |
R826886C004 (2001) R826886C004 (2002) R831709 (2005) |
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Thompson B, Coronado G, Puschel K, Allen E. Identifying constituents to participate in a project to control pesticide exposure in children of farmworkers. Environmental Health Perspectives 2001;109(Suppl 3):443-448. |
R826886C003 (2001) R826886C003 (2002) R826886C004 (2001) R826886C004 (2002) R831709 (2005) |
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, Toxics, Scientific Discipline, Health, RFA, Risk Assessments, Health Risk Assessment, Children's Health, Biochemistry, pesticides, Environmental Chemistry, neurological development, health effects, toxicity, organophosphate pesticides, assessment of exposure, susceptibility, paraoxonase polymorphism, pesticide exposure, biological response, children, environmental risks, organophosphates, growth & development, environmental health hazard, human exposure, Human Health Risk Assessment, neurotoxicity
Relevant Websites:
http://depts.washington.edu/chc/
Progress and Final Reports:
2000 Progress Report
Original Abstract
2002 Progress Report
Main Center Abstract and Reports:
R826886 University of Washington
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R826886C001 Molecular Mechanisms of Pesticide-Induced Developmental Toxicity
R826886C002 Genetic Susceptibility to Pesticides (Paraoxonase Polymorphism or PON1 Study)
R826886C003 Community-Based Participatory Research Project
R826886C004 Pesticide Exposure Pathways Research Project