ARS | Publication request: An analysis of the link between strokes and soils in the South Carolina coastal plains

Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 5, 2011
Publication Date: July 1, 2012
Citation: Ducey, T.F., Miller, J.O., Busscher, W.J., Lackland, D.T., Hunt, P.G. 2012. An analysis of the link between strokes and soils in the South Carolina coastal plains. Journal of Environmental Science and Health. 47(8):1104-1112.

Interpretive Summary: In the United States, stroke rates have dropped since the 1930’s except in the Southeast. This region, which includes the southeastern Coastal Plain region of North and South Carolina and Georgia, forms what is now known as the "Buckle of the Stroke Belt." People born within this region have higher rates of stroke, even after they migrate to other regions of the country. To determine if there was a link between soil properties and stroke rates, we correlated measurements of South Carolina soil characteristics obtained from the Natural Resources Conservation Service’s Soil Survey Geographic database to regional stroke mortality rates. Relationships between soil depth to water table, drainage class, hydric rating and pH to South Carolina stroke rate were demonstrated. This report results in the opening of a new frontier to determine the role of soil and water in human health.

Technical Abstract: The Stroke Belt is a geographical region of the southeastern United States where resident individuals suffer a disproportionately higher rate of strokes than the rest of the population. While the “buckle” of this Stroke Belt coincides with the southeastern Coastal Plain region of North and South Carolina and Georgia, there is a paucity of information pinpointing specific causes for this phenomenon. A number of studies posit that an exposure event – potentially microbial in nature – early in life, could be a risk factor. The most likely vector for such an exposure event would be the soils of the southeastern Coastal Plain region. These soils may have chemical and physical properties which are conducive to the growth and survival of microorganisms which may predispose individuals to stroke. To this aim, we correlated South Carolina stroke mortality data to soil characteristics found in the Natural Resources Conservation Service's Soil Survey Geographic database. In statewide comparisons, depth to water table (50 to 100 cm, R =0.62) and soil drainage class (poorly drained, R = 0.59; well drained, R = -0.54) both showed statistically significant relationships with stroke rate. In a 20-county comparison, depth to water table, drainage class, hydric rating (hydric soils, R = 0.56), and pH (very strongly acid, R = 0.66) all showed statistically significant relationships with stroke rate. These data should help direct future research and epidemiology efforts to pinpoint the exact exposure events which predispose individuals to an increased stroke rate.