Plasma and exhaled breath condensate nitrite–nitrate level in relation to environmental exposures in adults in the EGEA study

Abstract

This study evaluated the associations between biological markers in the nitrate–nitrite–NO pathway and four environmental exposures among subjects examined in the second survey (2003–2007) of the French Epidemiological study on Genetics and Environment of Asthma (EGEA). Total nitrite and nitrate (NO2- /NO3-) levels were measured both in plasma and in exhaled breath condensate (EBC) in 949 adults. Smoking, diet and exposure to chlorine products were assessed using standardized questionnaires. Exposure to air pollutants was estimated by using geostatistical models. All estimates were obtained with generalized estimating equations for linear regression models. Median levels of NO2-/NO3- were 36.3μM (1st–3rd quartile: 25.7, 51.1) in plasma and 2.0μmol/mg proteins (1st–3rd quartile 0.9, 3.9) in EBC. After adjustment for asthma, age, sex and menopausal status, plasma NO2-/NO3- level increased with leafy vegetable consumption (above versus below median=0.04 (95%CI: 0.001, 0.07)) and decreased in smokers (versus non/ex-smokers=−0.08 (95%CI: −0.11, −0.04). EBC NO2-/NO3- level decreased in smokers (−0.08 (95%CI: −0.16, −0.001)) and with exposure to ambient O3 concentration (above versus below median=−0.10 (95%CI: −0.17, −0.03)). Cured meat, chlorine products, PM10 and NO2 concentrations were not associated with NO2-/NO3- levels. Results suggest that potential modifiable environmental and behavioral risk factors may modify NO2-/NO3- levels in plasma and EBC according to the route of exposure.