Grantee Research Project Results
2004 Progress Report: Pesticide Exposures of Preschool Children Over Time
EPA Grant Number: R829363Title: Pesticide Exposures of Preschool Children Over Time
Investigators: Wilson, Nancy K. , Chuang, Jane C. , Lyu, Christopher
Current Investigators: Wilson, Nancy K. , Chuang, Jane C. , Strauss, Warren J. , Lyu, Christopher
Institution: Battelle Memorial Institute
EPA Project Officer: Aja, Hayley
Project Period: October 1, 2001 through September 30, 2005
Project Period Covered by this Report: October 1, 2003 through September 30, 2004
Project Amount: $1,340,414
RFA: Aggregate Exposure Assessment for Pesticides: Longitudinal Case Studies (2001) RFA Text | Recipients Lists
Research Category: Pesticides , Safer Chemicals , Human Health
Objective:
The effects on children’s exposures of recent changes in pesticide uses, such as those resulting from the federally mandated phase-outs of residential use of chlorpyrifos and diazinon and the increased use of alternative pesticides, are not well established. Thus, the main objective of this research is to estimate the longitudinal changes in aggregate exposures to targeted pesticides for selected preschool children in the same age group over 3 years. The targeted pesticides are or have been used in homes and school buildings, on lawns, and on pets. They include pyrethroid and organophosphate insecticides and acid herbicides.
The variability among preschool children’s exposures in similar microenvironments and among those in different microenvironments is also not well known. Thus, a second objective is to estimate the interpersonal variability of these exposures among preschool children living in different homes and among preschool children living in the same homes.
Progress Summary:
The research study, Pesticide Exposures of Preschool Children Over Time (PEPCOT), began in June 2002. The progress and accomplishments of PEPCOT in Year 3 of the project, from June 1, 2004, through May 31, 2005, are summarized below.
Human Subjects Research Protection
Continuation approval by the Battelle Institutional Review Board (IRB), which is required annually, was obtained for Year 3 of the project on October 7, 2004. A minor modification of the research protocol to allow laboratory analyses of a subset of the collected environmental and personal samples for additional chemicals, such as phenols and organochlorine compounds, was approved by the IRB on February 21, 2005.
Recruitment
In Year 1 of the project, the PEPCOT team successfully met the original recruitment goal of 50 households with 101 participating children. Participant recruitment and retention through Years 2 and 3 of the project continued to be successful. As of May 31, 2005, only two participating households had dropped out of the study (a 4% attrition rate), because of parents’ busy schedules and lack of time for participation. Current participants comprise 50 boys and 47 girls in 48 households, including 5 sets of twins and 1 set of triplets. A summary of the participating children by race, ethnicity, and gender is shown in Table 1.
White |
Black |
Hispanic |
Asian or Pacific Islander |
Native American |
Other |
Total |
|
Male |
43 |
3 |
0 |
0 |
0 |
4 |
50 |
Female |
38 |
3 |
2 |
0 |
0 |
4 |
47 |
Total |
81 |
6 |
2 |
0 |
0 |
8 |
97 |
% Total |
84% |
6% |
2% |
0% |
0% |
8% |
100% |
Field Sampling
The 50 participating households were each assigned to one of three groups for spring, summer, or fall sampling. By the end of May 2005, all field sampling (i.e., sampling for Years 1, 2, and 3) was completed for the households in the spring group. In Year 4 of the project, Year 3 field sampling will be completed for the summer and fall groups of participants. This will complete all field activities for the project.
Field samples were collected over 24 hours at each household. These samples include indoor and outdoor air, indoor floor dust, food-preparation surface wipes and floor surface wipes, children’s liquid and solid food by the duplicate plate method, hand wipes, and first morning urine or overnight diapers. For those children who were still being breast-fed, samples of breast milk were requested, although not always possible to obtain.
Additional information collected includes child activity diaries, house/building characteristics observations, and information on household, family, and residence characteristics and activities that may affect the children’s exposures, plus brief information on the children’s health that may be relevant to exposure measurements.
Scheduling appointments with the participants for field data collection remained the biggest challenge for the project. Our protocol requires that each participating household be sampled in the same season (and that each household remain in the original assigned study group) throughout the study period. However, families with young children typically have a very busy schedule, and the field team had to overcome frequent requests for sampling schedule changes. With our best efforts, we were still unable to sample two households in Year 2 because of their difficult schedules. Table 2 provides a summary of the numbers of households for which field data collection is complete, by year and study group.
Year |
Study Group |
Total |
||
A (Spring) |
B (Summer) |
C (Fall) |
||
1 |
17 |
14 |
19 |
50 |
2 |
16 |
12 |
18 |
46* |
3 |
16 |
0** |
0** |
16 |
Laboratory Analysis of Samples
On receipt of multimedia samples, the solid food samples were weighed and homogenized. The volumes of the liquid food samples were measured, the gels from the diaper samples were removed for storage, and the dust samples were sieved to collect the fine (< 150 μm) fractions. All of the collected samples were stored in freezers at temperatures below -10°C pending target chemical analysis.
Chemical analysis is in progress, with more than 20 compounds being measured in different sample matrices. These compounds include 2 organophosphate (OP) pesticides, 2 OP metabolites, 14 pyrethroid pesticides, 4 pyrethroid metabolites, 2 acid herbicides, and 1 phenol. These pollutants and their metabolites are divided for analysis into two groups, neutral and acidic, based on their chemical properties, as shown in Table 3.
Neutral |
Acidic |
Pyrethroid Pesticides |
Pyrethroid Metabolites Acid Herbicides Phenol |
The multimedia samples are solvent-extracted using Soxhlet, sonication, or accelerated solvent extraction techniques. Most samples require cleanup to remove potential interferences. Acidic compounds are derivatized by silylation or methylation, depending upon the compound. Concentrated extracts of all samples are analyzed by gas chromatography/mass spectrometry (GC/MS) in the selected ion monitoring mode. Standard operating procedures are used for sample preparation and analysis. Quality control (QC) samples are analyzed to assess the overall quality of the analytical results. These QC samples include: (1) field and/or laboratory duplicates; (2) matrix spike samples; and (3) field and laboratory blanks. Surrogate recovery standards are used to assess recovery in every sample.
Neutral and acidic pollutants and/or metabolites are measured in indoor and outdoor air, indoor floor dust, solid food, and hand wipe samples. Acidic pollutants and/or metabolites, except dicamba, are measured in urine and diaper samples. Floor surface wipe samples, when collected to replace floor dust samples from homes without carpet, are analyzed for neutrals and acids. Additionally, food-preparation surface wipe and hard-floor surface wipe samples, from homes where pesticides had been applied within 7 days prior to field sampling or during the 24-hour monitoring period, are analyzed for either neutral or acidic compounds depending upon the pesticides that had been applied.
All indoor and outdoor air, dust, hand wipe, hard-floor surface wipe, food-preparation wipe, urine, and diaper samples collected in Year 1 and 2 have been prepared and analyzed by GC/MS for the target pollutants/metabolites. Sample preparation and analysis of the Year 1 and Year 2 food samples for acidic pollutants have been completed. These data were imported into the PEPCOT database. The QA/QC checks of the PEPCOT imported data and sample preparation of Year 3 air samples are in progress. Sample preparation for neutral pollutants in solid food and breast milk samples will begin when the analytical methods have been validated.
Difficulties Encountered
During the initial project recruitment phase, the main difficulty encountered was the location and recruitment of families with two children, 3 years old and younger, who were willing to participate in an intrusive and burdensome study, not only once, but also for two additional sampling periods in the following years. Recruiting took far more time and resources than anticipated. During the follow-up phase, scheduling appointments with the participants for field data collection was the biggest challenge for the project. Families with young children typically have a very busy schedule. As a result, the field team had to overcome frequent requests for sampling schedule changes. With our best efforts, we were still unable to sample two households in Year 2 because of the participants’ difficult schedules.
Results to Date
Fifty households, as planned, were recruited into the study. In Year 3 of the project, Year 2 field sample collection was completed for all households, and Year 3 sampling was completed for the households in the spring group of participants. Sampling appointments were scheduled for the Year 3 summer group. Two or more children per household are PEPCOT participants, including five sets of twins and one set of triplets, for a total of 101 children. Two households dropped out in Year 2, one each from the spring and summer sampling groups; 48 households, with a total of 97 children, remain in the study. Laboratory analysis of the collected samples is in progress. All indoor and outdoor air, dust, hand wipe, hard-floor surface wipe, food-preparation wipe, urine, and diaper samples collected in Year 1 and 2 have been prepared and analyzed by GC/MS for the target pollutants/metabolites. Sample preparation and analysis of the Year 1 and Year 2 food samples for acidic pollutants has been completed. These data were imported into the PEPCOT database.
Future Activities:
In Year 4 of the project, Year 3 field sampling will be completed with the summer and fall groups of households. This will complete all field sampling activities. Laboratory analysis of the collected samples, statistical analysis of the data, and manuscript preparation for journal publication of PEPCOT results will continue. Communication of project findings to participants will begin. Because of the long time after field sample collection that is required to complete laboratory analyses, enter the data into the PEPCOT database, and analyze the data statistically, it is likely that we will request a 1-year no-cost extension of the project.
Journal Articles:
No journal articles submitted with this report: View all 8 publications for this projectSupplemental Keywords:
pesticides, herbicides, insecticides, sensitive populations, long-term exposure, pesticide exposure, pesticide residues, cumulative exposure, environmental management,, RFA, Health, Scientific Discipline, Toxics, ENVIRONMENTAL MANAGEMENT, Health Risk Assessment, Environmental Chemistry, pesticides, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Disease & Cumulative Effects, Children's Health, genetic susceptability, Molecular Biology/Genetics, Risk Assessment, health effects, pesticide exposure, cumulative exposure, urban air, sensitive populations, multi-pathway study, long term exposure, dermal exposure reduction model, age-related differences, exposure, dermal contact, air pollution, Human Health Risk Assessment, children, cumulative pesticide exposure, children's vulnerablity, assessment of exposure, human exposure, insecticides, pesticide residues, exposure pathways, age dependent response, dietary exposure, human health, long-term exposure, environmental hazard exposures, biomedical research, body burden, 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.