TRACE ELEMENTS IN TOENAILS AS A PREDICTOR OF ENVIRONMENTAL HEALTH RISKS IN AN ARAB AMERICAN POPULATION

Abstract

ISEE-149 Introduction: Assessment of exposure to trace elements in epidemiological studies is complicated by multiple exposure pathways, and therefore is improved through the use of biological markers. Toenails are often used as a biomarker of trace metal exposure, as many elements bind to the fibrous proteins in nails. In contrast to use of serum or plasma metal levels, levels of trace elements in toenails reflect average exposure to metals over 6–12 months and may be a more suitable biomarker for exploring the relationship between trace element status and disease. Methods: Metropolitan Detroit, birthplace of the automotive industry, is home to the largest Arab population in North America and continues to serve as a reception area for Middle Eastern immigrants. Exposure to current and historic industrial sources, low socioeconomic status, and barriers to health care place this population at high risk for environmental disease. Based on a previous study, 160 high risk households were identified in four Detroit Area communities. Respondents provided toenail clippings and completed questionnaires regarding health and economic status, demographics, and exposure to environmental risk factors. Toenail samples were washed, hot-block digested, and analyzed for Al, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Tl, and Pb using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Results: Logistic regression models, adjusted for age, gender and smoking, were run for 18 doctor-diagnosed diseases and reveal several significant relationships with toenail trace-element concentrations (Table 1).Table 1: Significant Associations between Trace Element Concentration in Toenails and Disease StatusSignificant Pearson correlation coefficients exist between metals released from local industry, including Cr and Cd, Mn and Pb, and Cr and Cu, suggesting a possible common source of exposure. Higher mean values for Al, Ni, Co, Cr and Cd in this study compared with other US populations supports this conclusion. Discussion: Diet, metabolism, disease status, and exposure to environmental contaminants all contribute to trace element concentration in nails. The observed associations between concentrations in toenails and disease status are likely reflective of a combination of these factors. Exposure to cobalt has previously been associated with lung diseases, and the association with selenium may lend insight into the role of antioxidants in disease protection. The positive association between diabetes and other trace metals is particularly noteworthy, suggesting that the disease may be influencing the metabolic cycling of these elements. This study provides insight into the association between trace element status and disease, establishing a basis for future investigations in this and other communities.