Grantee Research Project Results
2007 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 , Kerr, William L. , Hassan, Sayed
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, 2007 through March 31,2008
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 Summary:
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.
Laboratory Methods Development
With an eye toward understanding the potential for exposure misclassification through the use of biological markers of exposure and building upon our work from last year focusing on environmental degradation of pesticides, we have continued development of methods designed to improve understanding of the environmental and metabolic degradation of pesticides. We are now focusing on foods. Preliminary work suggest that a loss of pesticides spiked into food samples follows an exponential loss pattern for some pesticides, but is less clear for others. We are continuing our investigations through development of methods for the degradation products themselves so that we may see both the loss of parent pesticide and the expected increase in degradation/metabolite concentrations.
Children’s Study
We received supplemental funding to continue our work on Children’s Exposure the Fall of 2007 thus the main focus of our work this year has been on the Children’s Study. Beginning in April of 2008 and continuing through the reporting period, we recruited approximately 35 children in the age range of 3-6 years, and began detailed monitoring. We monitored their environment including yard soil, house dust, and food using a detailed protocol designed to assess the impact of environmental exposure and dietary exposure for organophosphorus and pyrethroid pesticides. Dietary exposure was examined in detail with multiple-day, duplicate-diet samples being taken and separated in eight different food categories. Separate analysis was done on each of the categorized food samples. In addition, multiple urine samples were collected from the child that were measured for volume then shipped to the Centers for Disease Control and Prevention for analysis of metabolites, both specific and general, for these pesticides. This protocol is to be repeated on the same individuals beginning in October 2008 and continuing through early March 2009. The simultaneous determination of parent pesticide concentrations in environmental and dietary samples with urinary biomarkers for the parent compounds affords validation of the exposure-biomarker link.
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 four-day duplicate diets, which were separated in 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 monitoring were completed. A manuscript detailing the relationship between urinary dialkyl phosphate concentration and environmental concentrations of parent pesticides is in preparation but awaits further analysis of biomarker samples. A manuscript describing the validity of the NHEXAS-Maryland food checklist for measuring adult food intake in dietary pesticide exposure studies is also in preparation.
Future Activities:
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 (3PBA) 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. 3PBA was detected in 75% of the NHANES samples, indicating widespread exposure among Americans. We conducted Tobit regression analyses of predictors of urinary 3PBA levels in children (age 6-10), teens (age 11-18), and adults (age 19-85), and found that certain foods and certain activities are significantly associated with elevated levels in the different age groups. The paper was published during the reporting period. See: Riederer, et al., Environmental Health Perspectives 116:1015–1022 (2008).
We are also analyzing data from the 1996 EPA-funded National Human Exposure Assessment-Maryland Study (NHEXAS-Maryland) 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. An early draft of the manuscript has been developed.
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 assessment
Progress 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
- 2006 Progress Report
- 2005 Progress Report
- 2004 Progress Report
- 2003
- 2002
- Original Abstract
4 journal articles for this project