Grantee Research Project Results
2003 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, 2003 through February 28, 2004
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 a pediatric population following genotoxic exposures. To achieve this objective, we willdetermine if children from an exposed population with elevated cancer incidence have experienced increases in chromosome aberrations or changes in hypoxanthine-guanine phosphoribosyltransferase (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 of 11 carcinogen-metabolizing enzymes are associated with increased 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 (CDC)-defined pediatric cancer cluster that has been linked to transplacental and childhood exposure to contaminated groundwater from two U.S. Environmental Protection Agency (EPA)-designated Superfund sites in Dover Township, NJ. The exposed siblings are the focus of the study rather than the children with cancer because of the genotoxic effects of cancer treatment. Biomarkers of susceptibility,however, 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 of the 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 our HPRT mutant frequency (Mf) analysis in 49 exposed siblings of children who developed cancer and 43 age/gender-matched unexposed children from neighboring communities. Our results demonstrated that cloning efficiencies (CEs) were significantly higher in exposed than unexposed children, whereas Mfs were not significantly different regardless of whether results were adjusted for age and CE (residual natural logarithm Mf [lnMf]). The fact that HPRT lnMf and residual lnMf were not significantly different does not preclude the possibility that significant genotoxic differences exist and are reflected in a change in the mutational spectrum. As a result, we have initiated our blinded mutational spectra studies in these two groups. To date, we have completed the mutational analysis on 133 HPRT T cell isolates from 27 of the 92 individuals. Because the analysis is blinded, we will not be able to interpret the results until all have been completed and the identification numbers are decoded. We also have made progress in our studies investigating the frequency of chromosomal aberrations in peripheral mononuclear cells from exposed children and unexposed controls to investigate the prevalence of widespread genomic damage and the association between genotoxic exposure and cancer risk. A major hurdle with this analysis was working out the conditions to generate good metaphase spreads from our cryopreserved mononuclear cell samples. We have overcome these obstacles, and consistently are able to generate slides with 500-700 high-quality metaphase spreads for fluorescence in situ hybridization (FISH) analysis. We have elected to use the Cytocell Chromoprobe-124, 356 (part no. PCM 356), treating with all three detection reagents for 2 dye (red/green), 6 chromosomes (1,2,4,3,5,6) identification for detecting chromosome aberrations.
Our goal is to score 1,000 metaphases from each sample. To date, metaphase spreads have been generated for 44 subjects, with the remainder to be generated during Year 2 of the project. We have begun the recruitment of peripheral blood samples for polymorphism studies from the affected siblings (children with cancer) of subjects studied in specific aim 1. In addition, we have developed a questionnaire for obtaining information about all residences and schools attended by the study participants that will enable us to determine potential exposure to contaminated drinking water. The questionnaire soon will be submitted to the University of Vermont Institutional Review Board, and will undergo formal pretesting following approval. One of the goals of the pretesting will be to determine if the questionnaire should be administered by telephone or mailed to study participants for self-completion. We also have been studying 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 the residential history of the subjects.
Future Activities:
We will complete our blind mutational spectra analysis of five mutants from each subject and begin our statistical analysis during Year 2 of the project. We also will move forward with completing our metaphase spreads and begin formal FISH analysis and scoring of these subjects. In addition, we will complete our sample acquisition of peripheral blood samples and begin quality testing for our polymorphism studies. We also will pretest our questionnaire on 20 volunteers from University staff and clinic patients. After final revision, we will administer the questionnaire to study subjects using either telephone or self-completion format, depending on the pretest results. Once questionnaires have been completed, data will be coded and entered into computer files. We then will begin our studies using the ATSDR EPANET 2 water-distribution model to estimate each subject's lifetime exposure to the various Dover Township water sources.
Journal Articles:
No journal articles submitted with this report: View all 12 publications for this projectSupplemental Keywords:
biomarkers, drinking water, risk assessment, human health, infants, children, genetic predisposition, hydrogeology, northeast, industry, vulnerability, environmental management, health, physical aspects, children's health, epidemiology, health risk assessment, molecular biology, genetics, physical processes, risk assessments, susceptibility, sensitive population, genetic susceptibility, human health risk assessment, assessment of exposure, biological markers, childhood cancer, children's vulnerability, computer models, contaminated groundwater, developmental effects, developmental neurotoxicology, environmental hazard exposures, exposure, genotoxic biomarkers, human exposure, neurobehavioral effects, neurodevelopmental toxicity, neurotoxic, pediatric cancer, residential populations., 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.