Relation of Whole Blood Carboxyhemoglobin Concentration to Ambient Carbon Monoxide Exposure Estimated Using Regression

• Published in: American journal of epidemiology 2010-04, Vol.171 (8), p.942-951
• Main Authors: Rudra, Carole B., Williams, Michelle A., Sheppard, Lianne, Koenig, Jane Q., Schiff, Melissa A., Frederick, Ihunnaya O., Dills, Russell
• Format: Article
• Language: English
• Subjects: Adult; air pollutants; Air Pollutants - adverse effects; Air Pollutants - analysis; Biological and medical sciences; Biomarkers; Biomarkers - analysis; Biomarkers - blood; Carbon monoxide; Carbon Monoxide - adverse effects; Carbon Monoxide - analysis; Carbon Monoxide Poisoning - blood; Carbon Monoxide Poisoning - diagnosis; carboxyhemoglobin; Carboxyhemoglobin - metabolism; Cross-Sectional Studies; Environment. Living conditions; Environmental Monitoring - methods; Epidemiology; Female; Human exposure; Humans; Linear Models; Maternal Exposure - adverse effects; Maternal Exposure - statistics & numerical data; Medical sciences; Multivariate Analysis; Pollutants; Practice of Epidemiology; Predictive Value of Tests; Pregnancy; Pregnancy Complications - blood; Pregnancy Complications - diagnosis; Pregnancy Trimesters; Prospective Studies; Public health; Public health. Hygiene; Public health. Hygiene-occupational medicine; Smoking - adverse effects; Time Factors; Washington
• ISSN: 0002-9262; 1476-6256
• DOI: 10.1093/aje/kwq022

Exposure to carbon monoxide (CO) and other ambient air pollutants is associated with adverse pregnancy outcomes. While there are several methods of estimating CO exposure, few have been evaluated against exposure biomarkers. The authors examined the relation between estimated CO exposure and blood carboxyhemoglobin concentration in 708 pregnant western Washington State women (1996–2004). Carboxyhemoglobin was measured in whole blood drawn around 13 weeks’ gestation. CO exposure during the month of blood draw was estimated using a regression model containing predictor terms for year, month, street and population densities, and distance to the nearest major road. Year and month were the strongest predictors. Carboxyhemoglobin level was correlated with estimated CO exposure (ρ = 0.22, 95% confidence interval (CI): 0.15, 0.29). After adjustment for covariates, each 10% increase in estimated exposure was associated with a 1.12% increase in median carboxyhemoglobin level (95% CI: 0.54, 1.69). This association remained after exclusion of 286 women who reported smoking or being exposed to secondhand smoke (ρ = 0.24). In this subgroup, the median carboxyhemoglobin concentration increased 1.29% (95% CI: 0.67, 1.91) for each 10% increase in CO exposure. Monthly estimated CO exposure was moderately correlated with an exposure biomarker. These results support the validity of this regression model for estimating ambient CO exposures in this population and geographic setting.