Exposure to the green environment is associated with improved biomarker-based indices of health and aging in adults

Background. Inadequate exposure to health-promoting natural environments exacerbates adverse effects of chronic stress and contributes to reduced life expectancy in disadvantaged populations. Biomarker-based composite indices of allostatic load, systemic inflammation, and biological aging enable quantitative assessment of pre-clinical health effects of environmental factors; these indices are known predictors of morbidity and mortality. Methods. This observational study in 335 adults in the Raleigh-Durham-Chapel Hill metropolitan area in North Carolina measured biomarkers of immune, neuroendocrine, and metabolic functions in blood samples, and DNA methylation status in leukocytes from 117 of these individuals. Allostatic load and inflammation indices were calculated by summing biomarker values dichotomized at health or distribution-based cutoffs. Epigenetic age was calculated from DNA methylation data using previously published definitions. Results. An interquartile range increase in tree cover within 500 m of residence was associated with 13% (2%; 23%) and 16% (4%; 27%) lower allostatic load and inflammation indices, respectively, and 1.8 (0.8; 2.7) years lower mean difference between epigenetic and chronological ages in individuals who spent at least 30 min outdoors daily, adjusting for demographic and behavioral data, obesity, chronic infections, and two-dimensional spline of geographic coordinates. In individuals with residential tree cover above the median, spending at least 3 hours outdoors daily was associated with 68% (52%; 83%) reduction in systemic inflammation compared to controls spending less than 30 minutes outdoors. This was not observed for low tree cover settings. Conclusion. Residential greenness is inversely associated with allostatic load and epigenetic aging. This abstract does not represent EPA’s policy.

Impact/Purpose

Deprived communities are exposed to disproportionally high levels of environmental hazards and also have insufficient access to urban green spaces and other health-promoting amenities. Combined effects of these factors contribute to the observed huge differences in life expectancies between wealthy and impoverished communities in many US cities. Our research focused on assessing sub-clinical health effects of urban green spaces and other community factors using biomarker-based indices of systemic inflammation and allostatic load as well as epigenetic age estimates based on DNA methylation measurements at multiple genomic sites. This study demonstrated that individuals who have more greenery around their residences had reduced allostatic load and inflammation indices, and lower epigenetic age compared to controls residing in less green settings. Allostatic load, chronic inflammation and accelerated epigenetic aging are known risk factors for systemic morbidity and mortality. Providing adequate access to the natural environment can improve health status and increase lifespan in urban residents.   

Citation

Egorov, A., S. Griffin, J. Styles, E. Klein, J. Kobylanski, L. Wickersham, E. Hudgens, AND Tim Wade. Exposure to the green environment is associated with improved biomarker-based indices of health and aging in adults. Society of Environmental Toxicology and Chemistry (SETAC) conference, Pittsburgh, PA, November 13 - 17, 2022.