Household air pollution, inflammation, and effects on hemoglobin concentration among pregnant women and infants

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PROJECT SUMMARY/ABSTRACT Household air pollution (HAP) is a leading risk factor for disease, particularly for the nearly 3 billion people worldwide who primarily use solid fuels (e.g. wood, coal, crop waste) for cooking. At the same time, anemia affects 613 million (33%) women of reproductive age and 270 million (42%) children under age five globally. The long-term goal of the proposed project is to strengthen the scientific evidence and justification for programs, policy, and research to address both household air pollution and anemia, through a combination of hypothesis- driven and discovery science. The overall objective for this application is to define biological mechanisms through which household air pollution may affect hemoglobin concentrations and to identify novel biomarkers associated with exposures and hemoglobin concentration. The central hypothesis is that multiple biological pathways are operating simultaneously and in opposing directions, potentially masking physiologically important relationships. The central hypothesis will be tested by pursuing two specific aims: 1) identify relationships between the intervention, exposures (PM2.5, carbon monoxide), levels of biomarkers of inflammation, and hemoglobin concentrations among pregnant women and infants enrolled in the Household Air Pollution Intervention Network (HAPIN) trial; and 2) in a subset of infants, identify novel biomarkers of associations between air pollutants and hemoglobin, using untargeted metabolomics and mediation analysis of metabolic perturbations. Both aims will use existing dried blood spots (DBS) collected from participants in the HAPIN trial site in rural Guatemala. Under the first aim, laboratory analyses of DBS from pregnant women (24-28 weeks gestation) and infants (age 6 months) will be performed for a panel of biomarkers of inflammation. The resulting data will be combined with existing data on participants’ exposures and hemoglobin concentrations in separate mediation models for pregnant women and infants, to examine potential pathways of effect. For the second aim, DBS from 100 infants (age 6 months) will be analyzed using an untargeted high-resolution metabolomics workflow, and resulting data will be analyzed for associations between metabolic signals, exposures to specific pollutants, and hemoglobin concentrations. The second aim will also involve an exploratory mediation analysis to examine patterns between exposures, metabolomic perturbations, and hemoglobin concentration, using a “meet in the middle” framework approach. The research proposed in this application is innovative because of its use of rigorous, cutting-edge methods that leverage the existing data, samples, and years of work already completed in the HAPIN trial, to generate new evidence and discoveries related to biological mechanisms linking household air pollution and anemia. The proposed research is significant because it is expected to provide a persuasive new argument for policymakers to promote and subsidize clean cooking, to reduce exposure to household air pollution as well as anemia prevalence among vulnerable populations, especially during the critical periods of pregnancy and the first year of life.