Effect of chronic low level manganese exposure on postural balance: a pilot study of residents in southern Ohio.

OBJECTIVE The objective of this study was to determine the effect of non-occupational exposure to manganese (Mn) on postural balance. METHODS Residents living near a ferromanganese refinery provided hair and blood samples after postural balance testing. The relationship between hair Mn and postural balance was analyzed with logistic regression. Following covariate adjustment, postural balance was compared with control data by analysis of covariance. RESULTS Mean hair Mn was 4.4 microg/g. A significantly positive association was found between hair Mn and sway area (eyes open on the platform, P = 0.05; eyes closed on the platform, P = 0.04) and sway length (eyes open on the platform, P = 0.05; eyes closed on the platform, P = 0.04). Postural balance of residents was significantly larger than controls in 5 out of 8 postural balance outcomes. CONCLUSION Preliminary findings suggest subclinical impairment in postural balance among residents chronically exposed to ambient Mn. A prospective study with a larger sample size is warranted.