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Nerl's Quest to Reduce Uncertainties in Children's Health and Risk Assessments

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Abstract: Data on children's exposure to chemical contaminants and their activities are very limited. Quantitative assessments rely heavily on major default assumptions as substitutes for missing information (Cohen Hubal et al. 2000a, b). The goal of the EPA/NERL measurement research program in support of the Food Quality Protection Act (FQPA) is to develop and evaluate approaches and methods for assessing children's aggregate exposure to pesticides and to conduct studies to collect data required to reduce reliance on default assumptions in development of quantitative exposure assessments. Based on an initial assessment of critical exposure pathways and factors, researchers in the NERL identified four priority research areas where there are critical data gaps. These areas include: (1) pesticide use patterns, (2) spatial and temporal distribution of pesticides in residences and child care centers, (3) factors influencing dermal and non-dietary ingestion exposures, and, (4) dietary exposure.

Collaborative efforts between the EPA/NERL and various research groups in other government organizations and academia have allowed us to conduct research to address these data gaps as follows:

To reduce uncertainties in non-dietary ingestion exposure: Previously unpublished data collected by the Fred Hutchinson Cancer Research Center (FHCRC) were analyzed to assess the mouthing behavior of 72 children (37 male/35 female). Total mouthing behavior data included the daily frequency of both mouth and tongue contacts with hands, other body parts, surfaces, natural objects, and toys. Statistical analyses of the data were undertaken to determine if significant differences existed among the age/gender subgroups in the sample. Results indicated that there was no association between mouthing frequency and gender. However, a clear relationship was observed between mouthing frequency and age.

To reduce uncertainties in dermal exposure: The Children's Post-Application Pesticide Pilot Study is a collaborative effort between the EPA/NERL and the Environmental and Occupational Health Sciences Institute (EOHSI) in New Jersey. Nine families with young children (<5 years old) were recruited to participate in the study. Homes were monitored for 28 days following a pesticide application. Four-hour videotape segments, time-activity diaries and questionnaires, cotton garments, and transferable residue loadings were collected during the study. Specific microenvironment and macroactivity combinations for these children were determined from the videotape segments and the time-activity diaries and questionnaires. Transferable residue loadings from the surfaces on which the children spent the majority of their time were measured using alcohol wipes. Cotton socks or pajama bottoms were used to calculate potential exposure to pesticide residues through the feet, knees, legs, and bottom. Transferable residues and cotton garment measurements were used to calculate transfer coefficients (TCs).

To reduce uncertainties in multiple exposure pathways: The Duval County Health Department (Jacksonville, FL), in collaboration with the Centers for Disease Control and Prevention and the EPA/NERL, conducted a research study to characterize young children's potential exposures to organophosphate and pyrethroid pesticides. The overall objectives of this study were to: (1) measure the urine metabolite levels of organophosphate and pyrethroid pesticides from a group of 4-6 year old children living in the greater Jacksonville area, (2) identify possible household sources of these pesticides by performing screening measurements and pesticide inventories, (3) investigate whether the environmental pesticide levels correlate with the biological levels, and, (4) correlate questionnaire exposure information with the environmental data. Results of the pesticide inventory showed that synthetic pyrethroids were the primary pesticides used in the residences. An aggregate exposure assessment was performed for a subset of nine participants that included collection of environmental (surface wipes, transferable residues, indoor/outdoor air) and personal samples (a time-activity diary, pesticide residues on cotton socks, duplicate diet, urine) to evaluate potential exposure from each route (inhalation, dermal, dietary, indirect ingestion).

To reduce uncertainties in pesticide use patterns in child care centers: The US Department of Housing and Urban Development, in collaboration with the Consumer Product Safety Commission and the EPA/NERL, conducted a research study to better understand the prevalence of pesticides, lead, and allergens in child care centers across the country. By participating in this study, EPA/NERL will obtain valuable information on pesticide usage in child care centers, concentrations of pesticides on surfaces in the centers that children may contact, and the distribution of pesticides within child care centers.

Data on mouthing behavior and the transfer coefficients will be presented during this seminar. In addition, a discussion of the study design, data analysis plan, and preliminary data for the Jacksonville and child care center studies will be presented.

These works have been funded wholly or in part by the United States Environmental Protection Agency under the following agreements: EPA Cooperative Agreement No. CR 816334-01 to the Fred Hutchinson Cancer Research Center; EPA Technical Services Contract No. 0D-5227-NAEX to the Environmental and Occupational Health Sciences Institute; EPA Technical Services Contract No. 1D-5377-NAGX to the Duval County Health Department; and EPA MOBIS Contract No. 23F-8144H to Westat, Inc. It has been subjected to Agency review and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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Citation:Tulve, N. S. Nerl's Quest to Reduce Uncertainties in Children's Health and Risk Assessments. Presented at Student Seminar for Brown Bag Lunch Series, Durham, NC, October 22, 2002.
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Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Division: Human Exposure & Atmospheric Sciences Division
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Branch: Exposure Measurements & Analysis Branch
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Product Type: Abstrct/Oral
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Presented: 10/22/2002
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Related Entries:
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Bullet Item Human Exposure Measurements Children's Focus
spacer Relationship Reason:   A Project of the Product
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Last Updated on Monday, October 22, 2007
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