PUBLIC HEALTH

Electromagnetic Fields and Public Health

Electromagnetic Fields and Public Health

Introduction

Over the past two decades, the possible relationship between human exposure to power frequency (50 and 60 Hz) electromagnetic fields (EMF) and adverse health outcomes has generated significant interest in both the scientific community and the general population. In the late 1970s and early 1980s, several epidemiology studies were published whose data suggested that adverse health effects may be seen in human populations receiving either occupational or environmental (i.e., residential) EMF exposures. Health effects associated with EMF in these studies included reproductive dysfunction, increased risk of birth defects and other developmental anomalies, and increased risk of cancer in several sites. These suggestive epidemiology data stimulated a large number of additional epidemiologic and experimental investigations, whose goals are to (1) confirm or refute the existence of specific health hazards of EMF exposure and (2) where such hazards are demonstrated to exist, identify EMF flux densities at which adverse health effects are observed, in order to quantify the risks of human exposure to EMF.

Important Strength Of Epidemiology

Clearly, the most important strength of epidemiology studies is that they are investigations of human responses to EMF exposure. As such, no interspecies extrapolations are required, and the EMF flux densities being investigated in epidemiology studies are, by definition, “real world.” For these reasons, any observation of a strong positive association between EMF exposure and risk of a specific disease would provide compelling evidence of a relationship between the exposure and that adverse health effect. Conversely, however, epidemiology studies are limited in that they can only demonstrate associations between an exposure and disease risk. Epidemiology cannot provide conclusive demonstrations of causality: spurious associations may be identified in epidemiology studies, and weak causal associations may be missed due to limited statistical power.

Role of Mechanistic Studies in EMF Hazard Assessment

The results of mechanistic investigations performed in experimental animals or in vitro model systems provide critical data that can establish the biological framework in which observed health effects of EMF can be interpreted. Although identification of a mechanism of action for a toxic agent is not essential for hazard identification, elucidation of one or more biochemical, molecular, or cellular pathways through which an agent exerts biological effects will clearly strengthen hazard assessments developed on the basis of epidemiology and animal bioassays.

Conversely, should the results of epidemiology studies and animal bioassays be negative or conflicting, the identification of a clearly definable mechanism of action can both (1) provide a rational biological context for hazard identification and (2) support the design of optimized hazard identification studies. However, should the results of epidemiology studies and animal bioassays be negative, the lack of an identified biological mechanism of action further weakens the assertion that a substantive human health hazard exists.

General Toxicity Studies Of EMF

In consideration of the absence of documented case reports of systemic EMF toxicity, it is generally agreed that acute, subchronic, or chronic exposure to EMF causes little or no systemic or generalized toxicity in ...