TEMPORAL VARIABILITY IN URINARY PHTHALATE METABOLITES, PHENOLS AND PHYTOESTROGENS AMONG CHILDREN

Abstract

ISEE-85 Introduction: Exposure to endocrine disruptors (ED) such as phthalates, phenols and phytoestrogens has been shown to be ubiquitous in the United States. Given their potential to perturb hormonal balance, it is of great interest to use biomarkers of exposure to these ED in epidemiologic studies. However, use of these biomarkers as reliable indicators of exposure requires an understanding of the time frame of exposure represented by a single measurement. Yet, data on the temporal variability of many ED biomarkers is sparse, especially among children. Aim: To address this gap in knowledge, we conducted a study of temporal variability in ED urinary metabolites among New York City (NYC) children. Methods: Thirty Hispanic and Black children (age range: 6-10 years) were recruited from East Harlem, NYC. A maximum of six serial urine samples were collected over a period of six months at the following approximate time intervals: two weeks, one month, two months, three months and six months. At each interview, spot urine samples (∼40 ml) were collected and a brief product-use questionnaire was administered. Urine samples were aliquoted and frozen at –20oC. Frozen samples were analyzed at the National Center for Environmental Health at the Centers for Disease Control and Prevention for ED (9 phthalate metabolites, 9 phenols and 6 phytoestrogens). Results: Preliminary data confirms previous findings of the omni-present exposure to these ED and we find some previously unreported results. The frequencies of detection range from 76% to 100% for phthalates, 63%-100% for the phenols and 53%-100% for phytoestrogens. Across samples analyzed to date, levels range from <1 μg/L (detection limit) to over 3000 μg/L for all three analyte groups. Final data analysis will include an assessment of inter-/intra-individual variability of these ED urinary biomarkers and an estimate of the reproducibility within child, for each biomarker. Discussion: This investigation will establish existing data on temporal variability of ED such as phthalates and will examine the reliability of ED measures such as bisphenol A. If intrapersonal variability is found to be high, results of this study can be used to guide the development of sampling strategies (e.g., pooling multiple samples on each child) for use of ED metabolite levels in epidemiologic studies. Acknowledgements: Supported by grants K01 ES012645, P01 ES009584-07, EPA RD 83171101, U01 ES 012771. We would like to thank Dana Barr, Centers for Disease Control and Prevention. This study could not have been carried out without the work of the dedicated Growing Up Healthy Study staff, Evelyn Cantillo, Ana Mejia, Arkeyris Richiez and Senaka Peter, as well as the participating children and their guardians.