Elevated Plasma Endothelin-1 and Pulmonary Arterial Pressure in Children Exposed to Air Pollution

Background: Controlled exposures of animals and humans to particulate matter (PM) or ozone air pollution cause an increase in plasma levels of endothelin-1, a potent vasoconstrictor that regulates pulmonary arterial pressure. Objectives: The primary objective of this field study was to determine whether Mexico City children, who are chronically exposed to levels of PM and O3that exceed the United States air quality standards, have elevated plasma endothelin-1 levels and pulmonary arterial pressures. Methods: We conducted a study of 81 children,$7.9 \pm 1.3$years of age, lifelong residents of either northeast (n = 19) or southwest (n = 40) Mexico City or$Polotitl\acute{a}n$(n = 22), a control city with PM and O3levels below the U.S. air quality standards. Clinical histories, physical examinations, and complete blood counts were done. Plasma endothelin-1 concentrations were determined by immunoassay, and pulmonary arterial pressures were measured by Doppler echocardiography. Results: Mexico City children had higher plasma endothelin-1 concentrations compared with controls (p < 0.001). Mean pulmonary arterial pressure was elevated in children from both northeast (p < 0.001) and southwest (p < 0.05) Mexico City compared with controls. Endothelin-1 levels in Mexico City children were positively correlated with daily outdoor hours (p = 0.012), and 7-day cumulative levels of PM air pollution $< 2.5 \mu m$ in aerodynamic diameter (PM2.5) before endothelin-1 measurement (p = 0.03). Conclusions: Chronic exposure of children to PM2.5is associated with increased levels of circulating endothelin-1 and elevated mean pulmonary arterial pressure.