Disentangling physical, chemical, nutritional and social environmental influences on asthma disparities: The promise of the exposome

Our understanding of the environmental influences on respiratory disease programming is growing increasingly complex with a multitude of environmental and microbial exposures (e.g., ambient pollutants, smoking, psychological stress, diet, indoor/outdoor allergens, viral infections, chemical toxins) playing a role. Moreover, the underlying pathogenesis of multifactorial diseases such as asthma, with variable onset, severity and natural history, reflect development-specific exposures and individual response to these exposures influenced by underlying genetic predisposition. Although traditional disciplinary research theory and methods have focused separately on how social and physical environmental factors affect childhood asthma, evolving research underscores important integrated effects. It is now widely accepted that advancing our understanding of asthma risk requires attention to both physical environmental hazards and social conditions. Populations of lower socioeconomic position are often disproportionately exposed to irritants (e.g., tobacco smoke), pollutants (e.g., diesel-related particles), and indoor allergens (e.g., cockroach and mouse allergen), as well as suffering greater nutritional inadequacies, all of which are known contributors to asthma morbidity. These individuals may also live in communities that are increasingly socially toxic that contribute to increased psychosocial stress which also influences asthma expression. Owing to the covariance across exposures and evidence that social stress and other environmental toxins (e.g., pollutants and tobacco smoke) may influence integrated physiological pathways (e.g., oxidative stress, pro-inflammatory immune pathways, and autonomic disruption), understanding the potential synergistic effects among physical, chemical, nutritional, and social determinants promises to more completely inform asthma epidemiology in general, and disease disparities specifically. The focus of this brief review is to highlight the promise of the exposome framework to better disentangle these complexities.