Protecting, maintaining and improving the health of all Minnesotans

March 7, 2001

Mr. Roger Conant

Powerline Task Force

2 Sunfish Lake

Sunfish Lake, Minnesota 55118

Dear Mr. Conant:

I am writing in response to your letters of December 22, 2000, January 19, 2001, March 4, 2001, and subsequent phone calls and e-mails which request the Minnesota Department of Health (MDH) to reevaluate its January 2000 EMF Assessment. This request appears to be based primarily on recent studies that have pooled data from several earlier studies and have reported an increased risk of leukemia among children exposed to high levels of EMF. In addition, you have referenced the recent conclusions of the British National Radiological Protection Board. I understand your concerns and request, but do not feel that a revision of our assessment is warranted at this time.

MDH staff have completed an evaluation of EMF research published since the January 2000 assessment, including an evaluation of the studies recently published in the British Journal of Cancer (2000, 83(5), 692-698) and Epidemiology (2000, (6), 624-34). As a part of this evaluation, MDH conducted a literature review to identify recently published EMF research in peer-reviewed scientific journals. MDH has concluded that the findings of the new research provide limited support, if any, to demonstrate that EMF causes leukemia.

The limitations of EMF epidemiological studies and these types of pooled analyses are widely acknowledged in the scientific community. Scientific proof of a causal association is established using multiple criteria, only one of which is epidemiologic association. Other important criteria in confirming causality (including strength of association, consistency and specificity of observations, appropriate temporal relationship, dose-response relationship, biological plausibility, and experimental verification) have not been met to support a purported relationship between EMF and leukemia.

The two recent reports cited above represent no new data, but rather a combining and re-analysis of data from selected studies that have been previously published. They include many of the same studies and their conclusions are similar: future studies should include more subjects at the highest exposure categories since there is little or no evidence of an association at levels to which most people are exposed. However, as the authors point out, there are many assumptions and limitations involved when combining and interpreting data from different studies, each of which has its own limitations, methodology, exposure assessment, potential biases, etc.

The results of these and other recently published EMF studies should be evaluated in the context of the extensive body of research that has been conducted over the last two decades. Evidence from laboratory studies, conducted at exposure levels as high as 20,000 milligauss, have failed to support an etiologic role of magnetic fields and leukemia. In addition, laboratory studies have failed to identify a plausible biological mechanism for how magnetic fields may initiate or promote the growth of cancer. The lack of confirming laboratory data raises considerable doubt about the weak and inconsistent associations reported in the epidemiologic literature.

MDH staff scientists are aware of the recent conclusions and recommendations made by the Advisory Group on Non-ionizing Radiation (AGNIR) to the British National Radiological Protection Board (NRPB). These conclusions are in fact similar to those of the National Research Council and the National Institute for Environmental Health Sciences. We agree with the AGNIR that the scientific evidence suggesting that EMF exposures causes an increased risk of cancer is very weak. We also agree that the laboratory data provide no support for an increased cancer risk due to EMF exposures (even at high exposure levels). AGN1R states that “the possibility remains that intense and prolonged exposures to magnetic fields can increase the risk of leukaemia in children,” but they acknowledge the limitations of the epidemiological studies, and state that the evidence is not conclusive. Specifically, in those studies in which measurements were made, the extent to which the more heavily exposed children were representative is uncertain. AGNIR also acknowledges that in studies where EMF exposures were estimated (rather than measured), results were based on such small numbers that findings could have been due to chance. As stated above, epidemiologic association does not, by itself, establish a cause and effect relationship between EMF and leukemia. AGNIR’s conclusions should be considered in the context of the study limitations, and the lack of supporting evidence in laboratory studies (even at high exposure levels).

In conclusion, the pooled analyses and the British review provide some useful information on the difficulties in integrating the vast body of EMF research and determining where future research might be focused. As with previous reviews, they cannot rule out an association between EMF and leukemia, but provide only limited support for a causal relationship between EMF and leukemia. MDH stands by the January 2000 EMF assessment as an accurate statement of what we know about EMF at this time.

I will also reiterate our previous statement that we consider it prudent public health policy to continue to monitor the EMF research and to support prudent avoidance measures. What avoidance measures should be considered “prudent” in response to limited and inconclusive evidence of a health risk is clearly a public policy decision. I encourage you to work with the local government officials who are entrusted with the decision regarding the Southeast Metro power line upgrade. I request that further communication from you be directed to Chuck Stroebel, who may be reached at 651-215-0919.

Sincerely,

/S/

Aggie Leitheiser, Assistant Commissioner

Minnesota Department of Health

cc: Michael Michaud, Department of Commerce

John Hynes, Environmental Quality Board

Kate O’Connell, Department of Commerce

Janet Gonzales, Public Utilities Commission

Susan Heffron, Pollution Control Agency

Frank Tiffany, Mayor of Sunfish Lake

Charles Mertensotto, Mayor of Mendota Heights

Kathleen Gaylord, Mayor of South St. Paul

Heidi Benedict, Xcel Energy

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