Metabolic Syndrome and Air Pollution Exposures in the Old Order Amish

Abstract

Metabolic Syndrome (MetS) is defined as the presence of at least three of the following factors: abdominal obesity, hypertension, hypertriglyceridemia, low HDL or hyperglycemia, insulin resistance, atherogenic dyslipidemia, proinflammatory state, and prothrombotic state. A little more than one-third of US adults are estimated to have MetS. It is hypothesized that air pollution may influence susceptibility to MetS through its effects on oxidative stress, inflammation, and other pathways. We are currently evaluating the association of MetS characteristics with chronic exposure to ambient particulate matter (PM2.5 and PM10) in the Old Order Amish from Lancaster County, Pennsylvania. The Old Order Amish are a genetically-closed homogeneous Caucasian population with social cohesiveness and similar socioeconomic status, limited use of prescription medication, lower relocation rates, high levels of physical activity, and obesity comparable to US rates. These attributes provide an opportunity for investigating the association of MetS with locally varying outdoor air pollution exposures. Using spatio-temporal models (that included geographic and meteorologic covariates) of monthly-average measured ambient concentrations, we have assigned monthly residential-location-specific exposure profiles to PM2.5 and PM10 between 1995 and 2007. In a preliminary cross-sectional analysis we have tested whether blood pressure, BMI, lipids and glucose measures are associated with PM2.5 and PM10 exposures adjusting for age, sex, and tobacco use. MetS was present in about 13% of the first 2408 Amish participants included. Preliminary analyses suggest associations between some MetS-related traits and PM exposures. For example each 10 ug/m3 unit increase in PM10 exposure in the prior month was associated with a 1.3-fold increased odds of having abdominal obesity (95% CI :1.0 -1.7). Analyses are ongoing.