Lead, Cadmium, Arsenic, and Cardiovascular Risk in Children

The main objective of this project is to test the hypothesis that exposure to metals in children will affect their cardiovascular risk and may predispose them to cardiovascular disease. It is based upon a growing epidemiological literature, by us and others, indicating that exposure to lead, cadmium, or arsenic increases cardiovascular risk. However, most studies of the impact of metals on cardiovascular risk have been carried out in adults, and the susceptibility of children to the cardiovascular effects of metals is largely unknown. <P> Primary hypotheses: 1) Exposures to lead, cadmium, or arsenic are positively associated with blood pressure levels in children; 2) Exposures to lead, cadmium, or arsenic, are positively associated with serological markers of inflammation and endothelial dysfunction (C-reactive protein [CRP], interleukin-6 [IL-6], intercellular adhesion molecule-1 [ICAM-1], and tumor necrosis factor alpha [TNF-alpha]) in children; and 3) Exposures, cadmium, or arsenic are inversely associated with heart rate variability in children. <P> Design and setting: We propose to conduct a cross sectional epidemiological study of the association between exposure to lead, cadmium, or arsenic and markers of cardiovascular risk in children residing in the Torresn metropolitan area, Mexico. We will contact the children who participated in the Torresn Study of Lead and Neurocognitive Function in 2001, when they were 6 - 7 years old. We expect to recruit 512 (85%) of the original study participants, who will be 14 - 15 years old at the time of field work for the present study in 2009. This population offers a unique opportunity to evaluate the cardiovascular effects of metals in a large and well characterized group of children whose lead exposure has been previously studied. In the present study, we will obtain two measurements of metal exposure two months apart (lead in whole blood and cadmium and arsenic in urine) and evaluate their association with cardiovascular risk markers. The primary outcomes will be blood pressure, serological markers of inflammation and endothelial dysfunction (CRP, IL-6, ICAM-1, and TNF- alpha), and heart rate variability. Other endpoints will also be assessed, including markers of renal proximal tubular injury, cardiometabolic abnormalities (insulin resistance and lipid levels), and neurotoxic endpoints. <P> Significance: Children in Torresn are exposed to lead, cadmium, and arsenic from dusts generated by the Met-Mex Peqoles smelter, the largest lead smelter operating in the Americas. While the average exposure to metals in this population is high, the range of exposure overlaps with that of children in US and in other Western countries. The current population thus represents an efficient way to obtain information on the impact of a wide range of metal exposure at the population level. The information obtained from children in Torresn will be relevant not only to local area residents, but to many children in the US and abroad. <P> PUBLIC HEALTH RELEVANCE: The main objective of this project is to test the hypothesis that exposure to metals in children will affect their cardiovascular risk and may predispose them to later cardiovascular disease. We propose to conduct a cross- sectional epidemiological study of the association between exposure to lead, cadmium, or arsenic and markers of cardiovascular risk in children residing in the Torresn metropolitan area, Mexico. Almost all studies of the impact of metals on cardiovascular risk have been carried out in adults, and the susceptibility of children to the cardiovascular effects of metals is largely unknown. The information obtained in this study will be relevant to millions of children in the US and abroad who are chronically exposed to lead, cadmium, and arsenic in the environment.