Letters to the Editor Re: "magnetic Field Exposure and Cardiovascular Disease Mortality among Electric Utility

Savitz et al. (1) recently published results of an analysis of cardiovascular disease mortality among electric utility workers in which they investigated mortality risk in relation to magnetic field exposure. They subclassified deaths from cardiovascular disease according to the death certificate codes. In particular, they considered arrhythmia-related deaths (International Classification of Diseases, Ninth Revision (ICD-9), codes 426 and 427), acute myocardial infarction (ICD-9 code 410), atherosclerosis-related mortality (ICD-9 code 440), and chronic/ subchronic coronary heart disease (ICD-9 codes 411-414) (2). Their aim was to identify causes of death likely to be reflective of changes in cardiac autonomic control. Savitz et al. state that the first two groupings are most likely reflective of changes in autonomic control and that the latter two classifications are not (1). It is my opinion that the death certificate is an unreliable and nonspecific source of information about autonomic control, and that it is not possible to draw any etiologic conclusions based upon these classifications.