Association between total blood mercury and exhaled nitric oxide in US adults

Exhaled nitric oxide (NO) levels as a noninvasive biomarker of airway inflammation and have been used to monitor environmental health effects. Mercury is a toxic environmental pollutant and is probable immunotoxic substance. We examined the association between blood mercury levels and exhaled NO levels in a representative sample of US adults. This investigation was a cross-sectional study of 3564 adults (≥20 years of age) who participated in the 2007-2008 National Health and Nutrition Examination Survey and provided measurements of exhaled NO and blood mercury levels. The exhaled NO measurements relied on the 2005 American Thoracic Society and European Respiratory Society equipment recommendations, and the mercury levels were measured using inductively coupled plasma mass spectrometry. The overall geometric mean values were 13.7 ng/g for exhaled NO and 0.97 μg/L for blood mercury. The subjects with mercury levels within the 4th quartile showed significantly increased exhaled NO levels (β=0.202; 95% CI, 0.104-0.300). Moreover, this association remained robust after risk factors related to exhaled NO levels and mercury exposure were adjusted for. Additionally, as the blood mercury levels increased, the adjusted mean levels of exhaled NO increased in a dose-dependent manner. Our study observed that blood mercury levels were significantly associated with elevated exhaled NO levels in US adults. This study implies the importance of exhaled NO as a measurement to assess health risks of environmental pollutants such as mercury.