Rationale, Study Design, and Cohort Characteristics for the Markers for Environmental Exposures (MEE) Study

Abstract

Environmental factors have been linked to many diseases and health conditions, but reliable assessment of environmental exposures is challenging. Developing biomarkers of environmental exposures, rather than relying on self-report, will improve our ability to assess the association of such exposures with disease. Epigenetic markers, most notably DNA methylation, have been identified for some environmental exposures, but identification of markers for additional exposures is still needed. The rationale behind the Markers for Environmental Exposures (MEE) Study was to (1) identify biomarkers, especially epigenetic markers, of environmental exposures, such as pesticides, air/food/water contaminants, and industrial chemicals that are commonly encountered in the general population; and (2) support the study of potential relationships between environmental exposures and health and health-related factors. The MEE Study is a cross-sectional study with potential for record linkage and follow-up. The well-characterized cohort of 400 postmenopausal women has generated a repository of biospecimens, including blood, urine, and saliva samples. Paired data include an environmental exposures questionnaire, a breast health questionnaire, dietary recalls, and a food frequency questionnaire. This work describes the rationale, study design, and cohort characteristics of the MEE Study. In addition to our primary research goals, we hope that the data and biorepository generated by this study will serve as a resource for future studies and collaboration.

Keywords: DNA methylation; biomarker; biorepository; environmental exposures; epigenetics.

Figure 1

Conceptual model for the MEE Study. The conceptual model includes both completed and potential (future) data collection. At the time of this writing, completed collections include all listed questionnaire-based data, biospecimens, epigenomic profile, urinary levels of glyphosate, organophosphate pesticides, and bisphenols A and S, and mammogram reports.

Figure 2

Study workflow. The MEE Study collected biospecimens and questionnaire-based data from 400 postmenopausal women aged 45 to 66 years residing in Southern California.

Figure 3

Flow chart of study recruitment. Recruitment for the MEE Study used two primary methods: personalized mailings to members of a breast cancer screening cohort (“Targeted Recruitment”) and general announcements in the community (“Community Recruitment”).