Grantee Research Project Results
2006 Progress Report: Measurements and Models of Longitudinal Dietary Intake of Pyrethroid and Organophosphate Insecticides by Children
EPA Grant Number: R829396Title: Measurements and Models of Longitudinal Dietary Intake of Pyrethroid and Organophosphate Insecticides by Children
Investigators: Ryan, P. Barry
Current Investigators: Ryan, P. Barry , Kerr, William L. , Hassan, Sayed
Institution: Emory University
Current Institution: Emory University , University of Georgia
EPA Project Officer: Aja, Hayley
Project Period: February 1, 2002 through March 31, 2010
Project Period Covered by this Report: February 1, 2005 through March 31, 2006
Project Amount: $659,764
RFA: Children's Vulnerability to Toxic Substances in the Environment (2001) RFA Text | Recipients Lists
Research Category: Human Health , Children's Health
Objective:
To measure longitudinal dietary exposure of selected insecticides in children, to evaluate the accuracy of children’s dietary exposure models, and to reduce model uncertainty. Our focus is on the validation of urinary biomarkers in children. By measuring environmental media—soil, house dust, food—and modeling intake, we will make a direct comparison to urinary metabolite concentrations.
Progress has been made on several fronts in this investigation. These may be categorized as Laboratory Methods Development, Children’s Study, Pilot Study, and Other Activities. We present a brief synopsis of results in each of these areas.
Progress Summary:
Laboratory Methods Development
As part of our ongoing laboratory methods development program, we have developed a multiclass degradation product method that enables us to look at both specific and non-specific degradation products of both organophosphate pesticides and pyrethroid pesticides. Two independent methods, based on ionic exchange and molecularly imprinted polymers (MIPS), have been implemented that offer complementary strengths in this analysis. Two manuscripts detailing this work are in the final stages of internal review and are scheduled for submission during the summer of 2007. During the reporting period, we also applied our food methods to house dust and achieved more satisfactory results with this method than with our previously developed method based on the soil extraction/analysis methods.
Children’s Study
Progress on the Children’s Study stopped in March 2005, due to a U.S. Environmental Protection Agency (EPA)-initiated hold on all pesticide exposure studies involving children. This hold was released in August 2006, and final EPA approval for the study was granted. We are currently in the re-planning stage for this study and are awaiting supplemental funding.
Pilot Study
In an effort to pilot our protocols for the Children’s Study, we undertook a study of adults working in our research facility. This study involved 11 individuals who kept 4-day duplicate diets, which were separated into nine food categories in accordance with our analysis protocol. Detailed dietary logs were kept as well and each food item weighed. The adults were asked to fill out an activity questionnaire indicating any activities likely to result in exposure to pesticides. Finally, each adult was asked to supply first morning and last evening void urine samples, plus a last evening void before the duplicate diet, and a first morning void after the duplicate diet (a total of 10 samples) for pesticide metabolite analysis. Two full cycles of this monitoring have been completed. We have presented results from this investigation in various scientific forums including the International Society for Exposure Analysis Annual Meeting. A manuscript detailing the relationship between urinary dialkyl phosphate concentration and environmental concentrations of parent pesticides is in preparation and is scheduled for submission during the summer of 2007. A manuscript describing the validity of the National Human Exposure Assessment-Maryland (NHEXAS-Maryland) food checklist for measuring adult food intake in dietary pesticide exposure studies is also in preparation.
Other Activities
Other activities include analyses of external data sets to help refine sampling protocols for the Children’s Study. We analyzed diet and non-diet predictors of the urinary pyrethroid metabolite 3-phenoxybenzoic acid (3-PBA) in the 1999–2002 U.S. National Health and Nutrition Examination Survey (NHANES). This survey is the first to analyze urinary pyrethroid metabolites in a nationally representative sample. 3-PBA was detected in 75% of the NHANES samples, indicating widespread exposure among Americans. We conducted Tobit regression analyses of predictors of urinary 3-PBA levels in children (ages 6–10), teens (ages 11–18), and adults (ages 19–85), and found that certain foods and certain activities are significantly associated with elevated levels in the different age groups. A manuscript is in the final stages of internal review and is scheduled for submission during the summer of 2007.
We are also analyzing data from the 1996 EPA-funded NHEXAS-Maryland Study to determine whether or not certain foods could be identified as key drivers of dietary malathion and chlorpyrifos intake among the NHEXAS subjects. Such information could help improve the accuracy of future dietary exposure studies, for example, by helping researchers focus on measuring consumption and residue levels of those foods likely to account for the greatest fraction of daily intake. We are using Tobit regression and Bayesian statistical approaches to evaluate which foods on the NHEXAS diet checklists explain the greatest amount of variability in malathion and chlorpyrifos concentrations in the duplicate diet samples. This research is a collaboration, with statisticians from the University of California Irvine and the University of West Georgia; a manuscript reporting results is currently in preparation.
Future Activities:
Future work on this project will focus on two areas: The Children’s Exposure to Environmental Pesticides (CEEP) Study, and manuscript preparation. Pending action and approval by EPA, we are proposing full implementation of the CEEP Study in August 2007. This activity will take about 9 months for data collection and an additional 6 months for laboratory and data analysis. It will require an extension of our current study time period through December 2008 and additional funding. The funding proposal is in review by EPA.
Several manuscripts are under development with many approaching the submission stage. In general, our target journals for these manuscripts include Environmental Health Perspectives for those manuscripts with a combination of environmental and biological data, and Environmental Science and Technology or Analytical Chemistry for the methods development papers. We realistically expect to submit six manuscripts between July 1, 2007, and December 31, 2007. These include the NHANES 3-PBA analysis study, a descriptive analysis of our adult study data, two manuscripts on methods development (environmental parent compounds and environmental pesticide degradation products), a manuscript reporting results of our effort to validate the use of the NHEXAS-Maryland food checklist to measure food intake in the adult study, and a manuscript relating total intake of pesticide to urinary metabolite output in our adult study.
Journal Articles:
No journal articles submitted with this report: View all 14 publications for this projectSupplemental Keywords:
exposure assessment, pesticides, pyrethroids, organophosphates, biomarkers, pesticide analysis, children,, RFA, Scientific Discipline, Health, PHYSICAL ASPECTS, Toxics, Air, Health Risk Assessment, air toxics, pesticides, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Physical Processes, Biochemistry, Children's Health, genetic susceptability, pesticide exposure, rural communities, urban air, sensitive populations, monitoring, adolescents, organophosphates, multi-pathway study, exposure, age-related differences, dermal contact, children, longitudinal study, human exposure, gender-related variability, pesticide residues, insecticides, environmental toxicant, neurotixics, dust , biological markers, dietary exposure, human health risk, agricultural community, organophosphate pesticides, exposure assessmentProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
- Final Report
- 2009 Progress Report
- 2008
- 2007 Progress Report
- 2005 Progress Report
- 2004 Progress Report
- 2003
- 2002
- Original Abstract
4 journal articles for this project