Grantee Research Project Results
2004 Progress Report: Analysis of Genotoxic Biomarkers in Children Associated with a Pediatric Cancer Cluster and Exposure to Two Superfund Sites
EPA Grant Number: CR830757Title: Analysis of Genotoxic Biomarkers in Children Associated with a Pediatric Cancer Cluster and Exposure to Two Superfund Sites
Investigators: Finette, Barry A. , O'Neill, J. Patrick , Vacek, Pamela
Current Investigators: Finette, Barry A.
Institution: University of Vermont
EPA Project Officer: Aja, Hayley
Project Period: March 1, 2003 through February 28, 2006 (Extended to December 31, 2007)
Project Period Covered by this Report: March 1, 2004 through February 28, 2005
Project Amount: $775,141
RFA: Children's Vulnerability to Toxic Substances in the Environment (2002) RFA Text | Recipients Lists
Research Category: Children's Health , Human Health
Objective:
The objective of this research project is to evaluate the utility of specific biomarkers of effect and susceptibility for studying cancer risk in children following genotoxic exposures. We will determine if children from an exposed population with elevated cancer incidence have an increase in chromosome aberrations or changes in hypoxanthine phosphoribosyl transferase (HPRT) mutational spectrum, such as: (1) an increase in frameshift mutations reflective of exposure to anthraquinone-based dyes and styrene-acrylonitrile trimers; (2) an increase in point mutations reflective of exposure to benzidine-based dyes, epichlorohydrin, and trichloropropane; and (3) an increase in V(D)J recombinase-mediated deletions reflective of exposure to aromatic hydrocarbons. We also will determine if specific DNA polymorphisms in 11 carcinogen-metabolizing enzymes are associated with increased mutagenic susceptibility to genotoxic exposure.
We will measure biomarkers of effect and susceptibility in exposed siblings of children in a Centers for Disease Control and Prevention-defined pediatric cancer cluster that has been linked to transplacental and childhood exposure to contaminated groundwater from two U.S. Environmental Protection Agency-designated Superfund sites in Dover Township, New Jersey. Exposure studies focus on the siblings of children with cancer rather than the children with cancer because of the genotoxic effects of cancer treatment. Biomarkers of susceptibility, however, also will be measured in children with cancer. Biomarkers of effect (chromosomal aberrations and HPRT mutations) in the exposed siblings will be compared to measurements in unexposed children from neighboring communities. Biomarkers of susceptibility (DNA polymorphisms for carcinogen metabolizing enzymes) in the exposed siblings and unexposed children will be compared to children with cancer to determine if the latter have a higher prevalence of specific metabolic genotypes. In addition, the relationships between biomarkers of effect and susceptibility in exposed siblings and unexposed children will be examined to determine if the effects of exposure are modified by any of these metabolic polymorphisms. Exposures in all subjects will be evaluated from their residential and personal histories using a computer model developed by the Agency for Toxic Substances and Disease Registry (ATSDR) to estimate exposure to different water sources over time.
Progress Summary:
We have completed and published our HPRT cloning assay analysis that measured the frequency of somatic mutations in 49 exposed siblings and 43 age/gender-matched unexposed children (Vacek, et al., 2005). These studies demonstrated that the somatic mutation frequency (Mf) in peripheral T cells from these children was not significantly different regardless of whether results were adjusted or unadjusted for age and cloning efficiency (Residual lnMf). The fact that HPRT lnMf and residual lnMf were not significantly different does not preclude the possibility that significant genotoxic differences exist at the genomic level, which would be reflected in a change in the mutational spectrum. To date, we have analyzed mutations in 310 T cell isolates from 72 of the 92 individuals.
These represent 291 unique mutations, for which the specific mutation has been determined in 242. The spectra continue to show an apparent increase in deletion/insertion mutations in the Toms River samples compared to our control spectrum and a decrease in V(D)J recombinase-mediated deletions. There also is preliminary evidence of an increased clonality of mutational events in the Toms River group as well. Because this analysis is blinded, we are not able to perform our comparative spectrum analysis between our test groups until the spectra analysis has been completed and the identification numbers are decoded. We have made good progress in our studies investigating the frequency of chromosomal aberrations in exposed and unexposed children to investigate the prevalence of widespread genomic damage and its association between genotoxic exposure and cancer risk. We have decided to increase the number of metaphases to be read per subject to 1,500, from our original goal of 1,000 per subject, to increase significantly the sensitivity of this analysis.
We completed the metaphase spreads and prepared cells for all 92 subjects to be studied. We have performed fluorescence in situ hybridization (FISH) analysis on 20 subjects to date. Because this analysis also is blinded, we are not able to perform our comparative analysis until the FISH analysis has been completed and the identification numbers are decoded. During Year 2 of the project, we completed the recruitment of peripheral blood samples from affected siblings of those subjects outlined in the Objectives section. This recruitment was done in cooperation with members of the group Toxic Environment Affects Children’s Health from Toms River, New Jersey. We have recruited a total of 33 peripheral blood samples from this cohort for the comparative polymorphism analysis. We have begun the development and testing of our PCR analysis for each individual gene that will be analyzed. The major complicating factors with these studies are controlling for background DNA from feeder cells required for expanded T cell clones and acquiring the appropriate controls for each polymorphism. These studies are moving forward and will formally begin in Year 3 of the project. In addition, we developed and tested our questionnaire for obtaining information about all residences and schools attended by the study participants to enable us to estimate potential exposure to contaminated drinking water for individual subjects. The questionnaire also contains questions regarding other potential exposures to genotoxic substances by both the participant and his/her mother during pregnancy. We are waiting for final Institutional Review Board approval of the questionnaire, which will occur this month. We have compiled all the necessary contact information (addresses and telephone numbers) for study subjects with the assistance of members of the Citizens Action Committee on the Childhood Cancer Cluster of Toms River. We also have started our analysis with the ATSDR Historical Reconstruction of the Water-Distribution System Serving the Dover Township Area, New Jersey, in preparation for estimating exposures to differing water sources based on subjects residential history.
Future Activities:
We will complete the double blind mutational spectra analysis of five mutants from each subject as outlined for specific aim 2 (increase in point mutations). We also will complete the FISH analysis for chromosomal aberration as described for specific aim 3 (an increase in V(D)J recombinase-mediated deletions) during the first half of Year 3, with the statistical analysis to be completed shortly thereafter. In addition, we will put significant effort into performing and completing the polymorphism analysis prior to completion of this grant. If that is not possible, then we will be required to request a no-cost extension to complete these studies.
We also will administer and analyze our epidemiologic questionnaire and compare our findings to the ATSDR EPANET 2 water-distribution model to estimate each subject’s lifetime exposure to the various Dover Township water sources. These findings will be analyzed with those obtained from our other biomarker studies.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 12 publications | 1 publications in selected types | All 1 journal articles |
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Type | Citation | ||
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Vacek PM, Messier T, Rivers J, Sullivan L, O'Neill JP, Finette BA. Somatic mutant frequency at the HPRT locus in children associated with a pediatric cancer cluster linked to exposure to two Superfund sites. Environmental and Molecular Mutagenesis 2005;45(4):339-345. |
CR830757 (2004) CR830757 (2005) CR830757 (2006) CR830757 (Final) |
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Supplemental Keywords:
biomarkers, drinking water, risk assessment, human health, infants, children, children’s health, genetic predisposition, hydrogeology, northeast, industry, vulnerability, sensitive population, genetics,, RFA, Health, Scientific Discipline, ENVIRONMENTAL MANAGEMENT, Health Risk Assessment, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Children's Health, genetic susceptability, Risk Assessment, developmental neurotoxicology, neurotoxic, sensitive populations, pediactric cancer, childhood cancer, biomarkers, computer models, developmental effects, genotoxic biomarkers, Human Health Risk Assessment, children, assessment of exposure, children's vulnerablity, residential populations, neurodevelopmental toxicity, human exposure, neurobehavioral effects, contaminated groundwater, biological markers, toxicsProgress 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.