2000 Progress Report: Total Organophosphours (Op) Pesticide Exposure Among Children in Urban and Rural Environments

EPA Grant Number: R825171
Title: Total Organophosphours (Op) Pesticide Exposure Among Children in Urban and Rural Environments
Investigators: Fenske, Richard , Lu, Chensheng (Alex)
Institution: University of Washington - Seattle
EPA Project Officer: Hahn, Intaek
Project Period: September 25, 1996 through September 24, 1999 (Extended to September 30, 2000)
Project Period Covered by this Report: September 25, 1999 through September 24, 2000
Project Amount: $600,145
RFA: Exposure of Children to Pesticides (1996) RFA Text |  Recipients Lists
Research Category: Pesticides , Children's Health , Health Effects , Human Health , Health , Safer Chemicals

Objective:

The recent National Academy of Sciences report, Pesticides in the Diets of Infants and Children (NRC, 1993), articulates the need to consider the unique qualities of children in assessing exposures to pesticides, and calls for studies to better characterize exposures from multiple sources and pathways. This study has two primary objectives: 1) characterization of geographic, temporal, age-related, and gender-related variability in total OP pesticide exposures in children; 2) determination of the relative contributions of environmental sources to total OP pesticide body burden in children. The extensive environmental and biological sampling proposed in this study will allow further refinement in field study protocols, sampling strategies, analytical techniques, and data interpretation for investigations of this kind.

Progress Summary:

This project is composed of three distinct projects 1) rural longitudinal biomonitoring study 2) urban cross-sectional biomonitoring study, and 3) total exposure pathway study.

Rural Longitudinal Biomonitoring, Study

A total of 57 children from 52 families participated in this study over the 21 -month period from December 1997 through August 1999. Originally the goal was to collect bi-weekly samples from each child until 26 samples were collected. However, individual children gave urine samples anywhere from 16 to 26 samples over a 21 -month period. A total of 998 urine samples were collected from 44 of the 57 children based on the following criteria:

1 - child must have provided at least one sample for three consecutive seasons.
2 - child must have provided samples during spray season (April-June).
3 - only one child per family was included in the analysis, one child was randomly excluded in order to maintain subject independence.

Twenty-six percent of the samples were not analyzed. These samples were spilled, lost, or had insufficient volume for analysis. The remaining 972 samples were analyzed for DAP metabolites and creatinine concentrations.

Preliminary results have indicated that elevated DAP concentrations were found in months when OP pesticides were sprayed in the field. The geometric means of both dimethyl and diethyl DAP for the urine samples collected during the spray months were significantly higher than those collected during the non-spray months (general linear regression procedure, p=.009 for dimethyl and p=.018 for diethyl DAP). Besides spraying OP pesticides in the orchards, a child's gender also affected his/her exposure to OP pesticides, but not age and the parental occupation. The geometric means of both dimethyl and diethyl DAP for the urine samples collected from male children were significantly higher than those collected from female children (p=.005 for dimethyl and p=.046 for diethyl DAP). This study suggests that there is temporal variation in agricultural children's exposure to OP pesticides. The elevated DAP levels in children found in certain months correlated with the reported uses of OP pesticides in the orchards located in the community. Elevated DAP concentrations were found in male children, a result that is not consistent with other published studies but warrants further investigation. This study, in conjunction with our previous studies and with studies published by other investigators, suggests that there is no association between OP pesticide exposure and children's ages or parental occupations.

Urban Cross-sectional Biomonitoring Study

We have completed the sample collection in November 1998 and sample analysis in September 1999. In total, 21 0 spot urine samples were obtained from I IO children aged 2-5 years, from 96 households. Urine samples were analyzed for six dialkylphosphate (DAP) compounds, the common metabolites of the OP pesticides. Parental interviews gathered demographic and residential pesticide use data.

Preliminary results have indicated that at least one of the DAP metabolites was measured in 99% of the children, and the two predominant metabolites (DMTP and DETP) were measured in 70-75% of the children. No significant differences were found in DAP concentrations related to season, community, gender, age, family income, or housing type. Median concentrations of dimethyl and diethyl DAPs were 0.11 and 0.04 [tmol/L, respectively (all children).

Concentrations were significantly higher in children whose parents reported pesticide use in the garden (0.19 vs. 0.09 gmol/L for dimethyl metabolites, p=.05; 0.04 vs. 0.03 gmol/L for diethyl metabolites, p=.02), but were not different based on reported pet treatment or indoor residential use. In conclusion, nearly all children in this study had measurable levels of OP pesticide metabolites. Some of this exposure was likely due to diet. Garden pesticide use was associated with elevated metabolite levels. It is unlikely that these exposure levels would result in acute intoxication, but the long-term health effects of such exposures are unknown.

Exposure Pathway Study

The sample collection from a total of 13 families, 7 urban/suburban and 6 agricultural families, and the analysis of all the samples were completed in 1999. The following samples were collected from the children and in and around their homes:

·Home environment 24-hour indoor air, house dust, soil, indoor and outdoor toy wipes
·Child's Diet Drinking water and 24-hour duplicate meal samples
·Child Hand wipes, 4 spot urine samples covering 24 hours

All samples were analyzed by the UW DEH Lab except for food samples which were sent to the Washington State University Food and Environmental Quality Laboratory. Envirom-nental samples were analyzed for the following OP pesticides:

·azinphos-methyl
·chlorpyrifos
·phosmet
·diazinon
·dichlorvos

We were unable to look for dichlorvos in the soil samples. We were unable to analyze the hand and toy wipe samples collected during the first round of sampling due to analytical interference of adhesives in the gauze pads used to collect the wipe samples. For the second round of sampling, the adhesives were extracted from the gauze prior to sample collection eliminating interference. Urine samples were analyzed using the same methods used in the other phases of the study. Urine samples are currently being analyzed at CDC in Atlanta for specific metabolites for the above OP pesticides.

Preliminary results indicated several key findings from this study

1. We found OP pesticides in more than one type of sample that we took from study homes, suggesting that children in the study may be exposed to OP pesticides from multiple sources.

2. Because the exposure patterns varied to a great extent, we were not able to identify a single source that contributes the most OP pesticide exposure to children in the study.

3. We found OP pesticide breakdown products in the urine samples. Although this suggests that some of the OP pesticides that were in participating children's diets and environment may have been absorbed into their bodies, these levels were considered very low.

4. When we looked at all children in the study, we did not find any associations between OP pesticide exposure and season (summer and fall), child's age, or gender. In other words, boys and girls with different ages had about the same amount of OP pesticide breakdown products in their urine in summer and fall.

5. We did not find any evidence of OPs in any of the drinking water samples from any of the homes. However, by the time these samples were analyzed, any pesticide metabolites present may have already degraded.

Future Activities:

More detailed data analysis for all phases of the study is the primary remaining task. We are working with biostatisticians on this regard, and will compare data among other grant recipients. Also the on-going activity is to analyze portion of urine samples for the specific metabolites of various OP pesticides in the Center for Disease Control and Prevention in Atlanta.


Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other project views: All 16 publications 4 publications in selected types All 4 journal articles
Type Citation Project Document Sources
Journal Article 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 Pt 2):662-671. R825171 (2000)
R826886 (2000)
R826886C004 (2001)
  • Abstract from PubMed
  • Full-text: Nature-Full Text PDF
    Exit
  • Journal Article Koch D, Lu CS, Fisker-Andersen J, Jolley L, Fenske RA. Temporal association of children's pesticide exposure and agricultural spraying: Report of a longitudinal biological monitoring study. Environmental Health Perspectives 2002;110(8):829-833. R825171 (2000)
    R826886 (2000)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Journal Article Lu CS, Knutson DE, Fisker-Andersen J, Fenske RA. Biological monitoring survey of organophosphorus pesticide exposure among preschool children in the Seattle metropolitan area. Environmental Health Perspectives 2001;109(3):299-303. R825171 (2000)
    R826886 (2000)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Journal Article 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. R825171 (1999)
    R825171 (2000)
    R826886 (2000)
    R826886C004 (2001)
  • Abstract from PubMed
  • Supplemental Keywords:

    Pesticide, Organophosphorus, Biomarker, Pacific Northwest, Agricultural., RFA, Health, Scientific Discipline, Air, Toxics, air toxics, pesticides, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Biochemistry, Children's Health, genetic susceptability, monitoring, pesticide exposure, rural communities, sensitive populations, urban air, organophosphates, multi-pathway study, age-related differences, dermal contact, exposure, children, human exposure, insecticides, pesticide residues, gender-related variability, environmental toxicant, biological markers, dietary exposure, dust , agricultural community, exposure assessment, organophosphate pesticides

    Relevant Websites:

    Synthesis Report of Research from EPA’s Science to Achieve Results (STAR) Grant Program: Feasibility of Estimating Pesticide Exposure and Dose in Children Using Biological Measurements (PDF) (42 pp, 3.87 MB)

    Progress and Final Reports:

    Original Abstract
  • 1997
  • 1998
  • 1999 Progress Report
  • Final