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Study Finds Magnetic Fields Do Not Raise Children's Leukemia Risk
A comprehensive study by researchers from the National Cancer Institute (NCI) and the Children's Cancer Group (CCG) found no evidence that magnetic fields (EMFs) in the home increase the risk for the most common form of childhood cancer.
In this case-control study, the researchers found that, in general, children who lived in homes with high measured magnetic fields were not significantly more likely to be diagnosed with acute lymphoblastic leukemia (ALL) than children living in homes with lower magnetic field levels. Nor was ALL found to be more likely among those whose homes were classified in high categories of "wire-code," a surrogate measure of magnetic fields that is based on the thickness, configuration, and distance from the home of nearby power lines.
"The results of our study differ from three earlier U.S. studies in that we found no evidence of a significantly increased risk of ALL among children whose main residence or residence during pregnancy was classified in the highest wire code category," said lead investigator Martha S. Linet, M.D., of NCI's Radiation Epidemiology Branch. The results are published in the July 3 issue of the New England Journal of Medicine.
Whether power frequency magnetic field exposures (EMFs) may increase cancer risk has been a controversial question, and nearly two decades of research has produced conflicting results. EMFs exist naturally inside the human body and in the surrounding environment. But stronger fields are produced by power lines and electric appliances, which have been the focus of most research. Recent research has focused on magnetic fields, specifically the 60 cycle-per-second (60 hertz) fields produced by alternating current (AC) in household electrical power.
The first study to suggest a risk from magnetic fields was published in 1979, when researchers reported that children who had died from leukemia or other cancers were about two to three times more likely than other children to have lived within 40 meters of a high-current power line. Several other groups of investigators later described similar findings based on proximity to power lines. When researchers have actually measured magnetic fields in children's homes, however, they have not found significantly increased risks of leukemia or other cancers.
Previous studies on magnetic fields and childhood cancer have had one or more shortcomings that make interpretation of their results difficult. These include small numbers of leukemia cases, measurements limited to a single residence, long intervals between leukemia diagnosis and magnetic field measurement, and data collectors aware of which children had leukemia (cases) and which did not (controls).
The NCI/CCG researchers designed their study to overcome these limitations as much as possible. A large study population covering nine states was chosen, and measurement technicians were unaware of case or control status. For most subjects, measurements were made within two years after diagnosis, and were obtained in both current and former residences. The measurements covered homes in which the child had lived for at least 70 percent of his or her life, or 70 percent of the five years immediately before diagnosis for children age 5 and older.
The researchers compared magnetic field exposures of 638 children with leukemia and 620 children without leukemia who were similar in age and race. About 58 percent of the children were under age 5, the age group in which ALL is most common. The participants lived in Illinois, Indiana, Iowa, Michigan, Minnesota, New Jersey, Ohio, Pennsylvania, and Wisconsin.
The researchers estimated magnetic field exposures in two different ways: by measuring fields in current and former homes of the children (including homes their mothers lived in during the pregnancy) and by assigning wire codes to the homes. Slightly less than half of all subjects had summary residential magnetic levels less than 0.065 microtesla (µT), close to 20 percent had levels ranging from 0.065 to 0.099 µT, 23 percent had levels ranging from 0.100 to 0.199 µT, and the remaining 12 percent had levels of 0.200 µT or higher.
If magnetic fields increased risk for ALL, the researchers would expect that the higher the measured level of magnetic fields in homes, and the higher the wire code category, the more ALL cases they would find. But in general, they did not see either of these patterns. For children living in homes with magnetic fields measured at 0.2 µT or above, the researchers calculated a slightly elevated, but not statistically significant risk for ALL compared with risk for children living in homes with magnetic fields below 0.065 µT. While risk of ALL appeared to be slightly higher among children residing in homes with high levels, the absence of a consistent pattern of increasing risk with increasing exposure level suggests that the slight increase seen could be due to chance.
In addition, the researchers found no relationship between wire code classification and risk for ALL. Children with ALL were no more likely than controls to live in homes with high wire-code classification.
The researchers also interviewed mothers of case and control children about the children's electrical appliance use and the mothers' appliance use during pregnancy. Results from this part of the study are still being analyzed and are expected to be published separately in 1998.
"This important study would not have been possible without the close collaboration and commitment of the physicians, nurses, and researchers of the Children's Cancer Group, and the cooperation of the families who participated," said Leslie L. Robison, Ph.D., a co-investigator in the study and professor of pediatrics at the University of Minnesota, Minneapolis. The Children's Cancer Group is a multicenter network of pediatric oncologists and other researchers from 38 institutions and affiliated hospitals who diagnose and treat approximately 50 percent of children with cancer in the United States.
The NCI/CCG study is part of a larger CCG investigation of ALL comprising more than 1,900 ALL cases and 1,900 controls. The larger study, overseen by Dr. Robison, is designed to evaluate the risk of ALL associated with a wide range of factors, including maternal diseases and medication use during pregnancy, childhood diseases, and other exposures such as parental occupation. Results are expected within the next two years.
FOR MORE INFORMATION: See Questions and Answers About the National Cancer Institute / Children's Cancer Group Study of Magnetic Fields and Childhood Leukemia on the National Cancer Institute website.
NOTE: For more detailed information on EMF and research on possible health effects, call the National Institute of Environmental Health Sciences' (NIEHS) Environmental Health Clearinghouse at1-800-NIEHS-94 (1-800-643-4794) to get a copy of the booklet Questions and Answers About EMF: Electric and Magnetic Fields Associated with the Use of Electric Power. This publication, produced by NIEHS and the U.S. Department of Energy, is also available on the World Wide Web at http://www.niehs.nih.gov/oc/factsheets/emf/emf.htm
RESIDENTIAL EXPOSURE TO MAGNETIC FIELDS AND ACUTE LYMPHOBLASTIC LEUKEMIA IN CHILDREN is a positive study showing an increase in the development of ALL in children exposed to powerline magnetic fields, masquerading as a negative study as a result of the National Cancer Institute's negative spin on the study's findings. The National Cancer Institute's mantra of "EMF research should stop here" does a disservice to the public who look to it for honest reporting of research findings, not slanted editorializing.
The Linet study, billed by the National Cancer Institute as "The most comprehensive study ever done on this much-debated topic", falls short of its billing as the study does not approach the thoroughness of the earlier Swedish studies and in fact, one significant flaw in the Linet study is the protocol whereby the powerline magnetic fields are measured in homes 2 years after the onset of ALL, whereas the Swedish studies measured the exposure levels during the crucial latent period and the onset of first exposure, clearly providing more accurate statistics.
The authors have chosen to declare their findings negative when in fact, the study shows a doubling of ALL in children exposed to 3 mG powerline magnetic fields.
And then, of course, there is the editorial authored by Edward W. Campion, M.D. that accomapined the Linet study in the New England Journal of Medicine. Dr. Campion's slanted editorial, gross miscalculations and misstatements would be ludicrous, if childhood leukemia were not so very serious and so very devastating.
Dr. Campion writes "Even directly under high-voltage transmission lines, the magnetic field is only 3 to 10 Mg, which is less than that in an electric railway car and much weaker that the magnetic fields close to my head when I use an electric razor." "This statement alone is evidence that the man knows not whereof he speaks" advises award winning author Paul Brodeur. Brodeur continued "the magnetic fields under a powerline are anywhere from 30 to 100 mG and oft times from 300 to 1,000 mG. Not the 3 to 10 mG Dr. Campion alleges. Further, children do not make a habit of sleeping in electric railway cars, nor do they keep an electric razor beside their cribs. The Linet study addresses chronic twenty-four hour a day involuntary magnetic field exposure from powerlines, not the two minute a day voluntary exposure that it may take Dr. Campion to shave with his electric razor."
"I suggest," continues Brodeur, "that parents would do well to distrust the National Cancer Institute and take positive steps to protect their children from exposure to powerline magnetic fields. The new Linet study clearly shows a statistically significant increase in the development of early childhood leukemia in children who live in close proximity to electric powerlines. Don't put your children's lives in the 'safe hands' of government arrogance."
The new Linet study is sure to be headline material in the next fews days as industry and government grab hold of NCI's spin and call the issue dead. It is important to remind our media that the only thing dead about this issue, is the children living too close to overhead powerlines.
It is common to find levels above this near to power-lines, electricity substations and in many city houses. At levels between 0.4 and 0.5 microtesla (still over 3000 times lower that official UK NRPB Guidance of 1600uT ) the study found 3.28 times the number of expected cases.
The Linet study, billed by the U.S. National Cancer Institute as "The most comprehensive study ever done on this much-debated topic", falls far short of its billing as the study does not approach the thoroughness of the earlier Swedish studies, and INCREDIBILY for a modern study it only measured MAGNETIC fields and did NOT include ELECTRIC fields which are being increasingly implicated in cancer development and many other adverse health conditions. Both magnetic and electric fields are being measured in the landmark UK Childhood Cancer Study due out early next year, as UK researchers understand the potential importance of electric fields. In a 1996 Canadian study on adults which took BOTH fields into account, the risk rose from 1.6 (magnetic fields only, and similar to the 1.79 in this study) to 11.2 (both magnetic and ELECTRIC fields considered) - it is likely to be a similar increase for children.
It is accompanied by an Editorial authored by Edward W.Campion, M.D., which contains mis-calculations and mis-statements and, incredibly, includes a call to halt EMF research. The Linet study addresses chronic twenty-four hour a day involuntary magnetic field exposure, not the two minute a day voluntary exposure that it may take Dr. Campion "to shave with his electric razor". There is clearly a hidden agenda at work here.
The results were: Unmatched cases contr. OR 95%CI <0.065uT 267 281 1.00 0.65-0.099 123 117 1.10 0.0-0.199 151 143 1.10 =>0.2 83 70 1.24 0.2-0.299 38 42 0.92 0.3-0.399 22 17 1.39 0.4-0.499 14 5 3.28 =>0.5 9 6 1.41 Matched cases contr. OR 95%CI <0.065uT 206 215 1.00 0.65-0.099 92 98 0.96 0.0-0.199 107 106 1.15 =>0.2 58 44 1.53 0.2-0.299 29 26 1.31 0.3-0.399 14 11 1.46 0.4-0.499 10 2 6.41 =>0.5 5 5 1.01The new Linet study is sure to be headline material in the next few days as industry and government grab hold of NCI's spin and try to call the issue "dead". It is important to remind ourselves that the only thing dead about this issue are the children who lived too close to electricity.
Powerwatch runs a public information service on power-frequency and microwave EMF issues (including cellular phone hazards) in an attempt to provide all sides of the story in this manipulated area of research and public policy.
For our further information call: (UK) 01353 778814
Don MacPhee fron LaTrobe University's school of microbiology states in The Australian that the results of the NCI Study backed his claims that power lines did not emit enough energy to cause childhood cancer or any other form of cancer.
Mac Phee said that it was mostly the media and scientists of "Dubious Quality" that had perpetuated the myth that there was any link between power lines and cancer. "Its just absolute non-sense", Dr. McPhee said.
This line is also being actively pushed by the media in the US and is being promoted as proof that future funding for research should cease.
It is unfortunate that reporters and so called experts who are now calling the NCI study as positive proof that a risk does not exist from long term exposure to powerline electromagnetic fields did not take the time to critically examine what the study actually found, and to examine the criteria which led to the NCI researcher's conclusions.
The researchers actually acknowledge in no less than four places, a statistically significant increase in acute lymphoblastic leukaemia (ALL) in children exposed to powerline magnetic fields in excess of 3 milliGauss. This is a CONFIRMATION of many previous studies which have shown a similar level of association between childhood leukaemia and magnetic fields from electricity. The article in The Australian mentions that the researchers dismissed as a "statistical fluke"a 24% increase in leukemia risk for children exposed to what is termed "especially high magnetic fields".
The NCI researchers were able to dismiss this fact by arbitrarily setting a 2 mG level as a cut-off limit. The fact is, that if they had used the 3 mG level as a cut off point in their calculations, the conclusions would have been exactly the opposite - that there is a significant risk.
On july 4th EMFacts e-mailed Professor Ross Adey, one of the most respected bio-electromagnetic researchers in the U.S. Dr. Adey is the author of numerous books and research papers on the bio-effects of EMFs. He recently conducted a $3 million research program for Motorola. His reply on the NCI study is as follows:
"A number of us worked on the NCI paper through last weekend. Sam Milham, the Washington State epidemiologist and a pioneer in this field, points out that if they had included the 3mg level in their cutoff, the conclusions would have been exactly the opposite - that there IS a significant risk. And selection of 2mG is quite arbitrary. David Savitz used 3mG in some of his work. Obviously there is no steep threshold beyond which risks rise exponentially.
At the recent Bologna International Symposium, Schuz from U. Mainz had a paper combining kids from Berlin and Southern Saxony in high exposure homes to give leukemia odds ratio of 6.8 for young kids (under 4yrs). So the dismissive attitude of NCI is totally unrealistic."
Surprisingly, for a modern study, the NCI researchers only measured MAGNETIC fields and did NOT include ELECTRIC fields which are being increasingly implicated in cancer development and many other adverse health conditions. Both magnetic and electric fields are being measured in the landmark UK Childhood Cancer Study due out early next year, as UK researchers understand the potential importance of electric fields. In the 1996 Ontario Hydro adult worker study conducted by Dr. Antony Miller of Toronto University in Canada, when they took both fields into account, the risk rose from 1.6 (magnetic fields only, and similar to the 1.79 in this study) to 11.2 (both magnetic and ELECTRIC fields considered) - it is likely to be a similar increase for children.
It should also be noted that the magnetic field is not the equilivant of EMF. It is only one of the now "five or six" known EMF metrics. Of these, the electric field may well be the most important, though the role of transients, harmonics, ground currents, radon daughters and the radiofrequencies that "ride" on power lines are also suspect. Any study which only considers one of these metrics cannot give any assurance of "safety".
If we extrapolate to the evidence (Electromagnetics Forum , Vol.1,No.2 p.5-6 ) that levels of 12 mG affect the ability of melatonin to suppress cancer cells and that there is some evidence of a dose-response relationship between 2 and 12 mG, then at levels at or below 2mG, a no effect result could well be expected.
With this in mind, the only thing the NCI indicates is that children with magnetic field exposures at 2 mG and under are not at increased risk of developing leukemia from their EMF exposure. Rather than exonerating EMFs, the NCI study gives further support for the 1995 draft guidelines from the U.S. National Council of Radiation Protection and Measurements. (NCRP) These guidelines generally endorses a 2mG exposure limit.
As stated in the NCRP's conclusions:
"In arriving at the proposed guidelines, the committee has considered available laboratory studies on bioeffects and epidemiological reports of health hazards from electric and magnetic field exposure. . . In key areas of bioelectromagnetic research, findings are sufficiently consistent and form a sufficiently coherent picture to suggest plausible connections between ELF EMF exposures and disruption of normal biological processes, in ways meriting detailed examination of potential implications in human health."
What was surprisengly NOT reported in the Australian media was the release of a much larger Swedish EMF human exposure study less than three weeks before the NCI study. The Swedish study included approximately 400,000 subjects who had lived within 300 meters of transmission lines in Sweden for at least one year between 1960 and 1985. The researchers found that persons who were exposed to magnetic fields both at home and at work are nearly 4 times likely to develop leukemia than those who were not exposed to magnetic fields.
To quote from the Epidemiology Press Release of 16 June 1997:
Exposure to Magnetic Fields at Home and at Work Increases Risk of Leukemia
"Dr Maria Feychting and colleagues at the Karolinska Institute and the National Institute for Working Life in Sweden report in the July issue of Epidemiology that persons who were exposed to magnetic fields both at home and at work are nearly 4 times likely to develop leukemia as those were not exposed to magnetic fields.
Dr. Feychting and colleagues conducted a case-control study from among approximately 400, 000 subjects who had lived within 300 meters of transmission lines in Sweden for at least one year between 1960 and 1985. The investigators designated as cases 325 residents diagnosed with leukemia and 223 residents diagnosed with a tumor of the central nervous system. For each case identified, they selected at random at least two control subjects of the same sex and five-year age group who had lived in the same parish as the case.
They assessed exposure to magnetic fields generated by transmission and distribution power lines close to each subject's house, excluding buried power cables from the calculations. They obtained information on each subject's occupation from five-year censuses. They assessed occupational magnetic field exposures for each subject through extrapolation of exposure estimates for each occupation and without knowledge of weather the subject was a case or control. The investigators took into account in their analysis other occupational exposures, such as benzines, oil products, solvents, and welding fumes, that have been associated with leukemia in earlier studies. They compare the residential and occupational histories of the cases with the histories of controls.
Subjects in the highest category of occupational exposure to magnetic fields (0.20 microT) had nearly double the risk of developing acute myeloid leukemia, a 40% increase in risk of developing chronic myeloid leukemia, and a 70% increase in risk for chronic lymphocytic leukemia when compared with unexposed subjects. Those with high levels of exposure to magnetic fields at home had double risk of developing acute myeloid leukemia and chronic myeloid leukemia as those who were unexposed.
Among subjects who had high exposures to magnetic fields at home and at work, the risk of developing acute myeloid leukemia and chronic myeloid leukemia increased more than 6 fold and doubled for chronic lymphocytic leukemia when compared with subjects who had not been exposed to magnetic fields. Results for central nervous system tumors were consistent with no increase in risk."
One possible reason why the Swedish study was not reported and the NCI was, is the fact that, according to the Report of the Panel on Electromagnetic Fields and Health to the Victorian Government , Sept 1992, to quote:
"To date the responsibility for communicating with the community about ELF fields has rarely been clearly defined and most information is developed and disseminated by the utilities, as health authorities have not considered ELF fields as an important health matter."
The NCI study can be put into the same classification as the NAS/NRC review study.(Electromagnetics Forum, Vol.1, No.2, p.1-4 ) Both studies come up with conclusions based on serious omissions of hard scientific data which do not fit in with those conclusions.
Both these studies are now being used by those wishing to end further EMF research. When you look at the tobacco health issue history, you will find that similar efforts to stop or curtail research spending was one of the tactics used-- along with belittling research findings that indicated a health hazard existed. For some years those attempts to stymie research on the tobacco problem were successful. Lets hope that tactic will not be successful here.
The National Cancer Institute may well consider that research money should be better spent in other areas than EMF research. To be fair to the NCI, when you consider the millions prevously spent on EMF research and that figures indicate that the number who live above 2mG in the U.K., Sweden and Italy is only estimated to be about 0.5% of the population, there is a need to re-prioritise future research. The many large and expensive epidemiological studies that looked at magnetic fields only have really "had their day". They show that there is an effect, maybe on a susceptible sub-group in the population, and the effect is NOT very large for magnetic fields alone. It is now time to think very carefully how we spend future research money, to carefully look at the other metrics of EMF exposure as mentioned earlier, and also to adopt a policy of prudent avoidance, along the lines recommended by the draft NCRP report.
"All in all, this study indicates that if there is an association between magnetic fields and cancer, it is very weak. It makes one wonder how much more money we want to throw at this subject, because basically we can't see anything definite," said Dr. Lawrence Fischer, director of the Institute for Environmental Toxicology at Michigan State University."
"The researchers measured magnetic fields in all the houses where the children had lived for five years before the discovery of their cancer, as well as in the homes where their mothers lived while pregnant." [The A.P. writer.]
"We found no evidence that magnetic field levels in the home increased the risk for childhood leukemia," said Dr. Martha S Linet, who directed the study.
THE STUDY FINDING (ABOUT *MAGNETIC FIELD* AND LEUKEMIA ASSOCIATION) IS ***NOT*** NEWS..........
We must start our analysis of the study here!!!
The study results can hardly be a surprise to those who have been closely following EMF research results of the recent three or four years! (But that CERTAINLY does not mean that such headlines as "Power lines not a cancer risk for kids," -- USA TODAY -- are justified.)
The study outcome (as it was configured -- poorly) certainly is not surprising to those who attended the recent NIEHS sponsored symposium in Durham, North Carolina. Guru has previously reported that the final wrap-up session discussed: the need to better explain (or "link") the epidemiological findings concerning power line "proximity -- which even the NAS study had confirmed -- with childhood leukemia.
[Three of guru's previously published web-site messages relate to the above ... and the discussion which follows: "EMF Problem NOT simple," http://www.feb.se/EMF-L/EMFL-2-97.html; "Quality of Measurements/ Transients," http://www.feb.se/EMF-L/EMFL-7-97.html; Also, a brief reference to the results of the Durham meeting which contains the following statement: We think it cannot be said too often: there is much more to the EMF problem than "magnetic fields and gauss meter readings." -- http://www.feb.se/EMF-L/EMFL-6-97.html.]
By the time of the Durham meeting, the question (within the research community) clearly had become:
WHICH particular "metric" of the EMF phenomena is responsible (or "the most" responsible) for the adverse health effects in the power line case?
[Recently, guru forwarded to EMF-L a copy of a recommended paragraph (to an NIEHS draft) which addressed that aspect. Some of you might want to revisit that recent item as well..... Also, it is important to ALLOW FOR THE POSSIBILITY that not ONE metric, alone, may be guilty. They may act in combination, e.g., magnetic field plus strong transients or plus "radon daughter" effect, etc.]
And ... as the quotes above show, the NCI study dealt with the magnetic field (MF) "metric" and not the others!!!!
So ... what ... should we be looking at with greater scrutiny and intensity? After all, the epidemiology is still there ... showing that SOMETHING -- if not the MF -- is biologically interacting with cells or tissue!
THE OTHER METRICS........
The failure of the NCI study to deal with the "electrical" field is really inexcusable, given the growing number of reports and studies within the research community in recent years that have discovered a closer association with the "electric" than with the "magnetic" component of EMF.....
Perhaps best remembered (by EMF-L members) in that regard is the Ontario Hydro study conducted by Dr. Anthony Miller of Toronto University in Canada. That study was briefly discussed by guru in the web-site message "A Change In the Wind," << http://www.feb.se/EMF-L/EMFL-9-96.html >> That is the message which commented: "When the history of the EMF saga is written, this study will mark the death of the canary." I still regard that as likely......
Another important reference to this aspect which is clearly embedded in guru's mind was the report given in San Antonio last November by Dr. Bill Kaune which summarized his conclusions after comparing epidemiological (MF) data in Sweden with actual power information made available by the Swedish government. He told the assembled gathering of researchers (paraphrased): We need to divert our attention to other aspects than the magnetic field in order to find that closer association with cause and effect that we seek. He was clearly referring to the electric field. (This statement is written from memory. Hope Bill will refine it as necessary......His report was one of the highlights of that San Antonio meeting.)
Also, we should not overlook the importance of that McGill University study in Canada (Drs. Armstrong and Theriault) which was perhaps the first to show a stronger connection between electrical "transient" activity and adverse health effects. (I intend to go into my files and see if I can find Louis Slesin's commentary about that study perhaps a year ago here on EMF-L. If I can find it, I'm going to send it to all of you.)
That is the study which has had the misfortune of having the data "seized" by the utility company because they did not like the results...... So, it is not easy to compare it with current study efforts ... but it remains one of the most conclusive ... showing a cause and effect between EMF and health damage, i.e., biological interaction. Some have suggested that the McGill study should not be considered in the childhood leukemia scenario because it was a "workplace" study. I regard that kind of argument as a disingenuous self-serving effort to "compartmentalize" our research unrealistically. If "transients" of ELF frequency current are important in one environment, what is the justification for saying they do not count in the home. The same argument has been raised about Tony Miller's hydro study. It is equally specious in that case.....
Some of guru's web-site references provided above will make it clear that "I" think this a major flaw in our research program to date!!!!
Does everyone understand what the "transients" are? They are (1) the "spikes" of energy that occasionally occur on electric lines. You see them as the "blips" of energy that show up on cathode ray scopes ... or the "surges" of current that cause you problems sometimes with your computer or electric digital clocks. Suddenly -- with out any actual or visible loss of power -- all your clocks are blinking on and off at you. Most people now have obtained "surge protectors" for their sensitive electrical equipment ... and most of these adequately take care of THAT problem.....
But (2) there is another kind of transient that is probably the more serious. That is the kind that is caused by electrical storms that interact with your power lines. ***I DO NOT BELIEVE WE ARE GOING TO SOLVE THE "PROXIMITY" ISSUE WITHOUT UNDERSTANDING WHAT HAPPENS TO A POWER LINE IN AN ELECTRICAL STORM.*** And what these storms can do to the line's potential for biological interaction......!!!!! They can also have a dramatic effect on transformers or substations.
To my knowledge, none of our research has attempted to analyze the effect of electrical storms upon the EMF metrics or the EMF effects.......
One physicist has described it thus to me: "billions of free flying high energy electrons" are suddenly engulfing and disturbing the "normal" EMF field produced by the line.....This (I am told) can produce electrical and magnetic fields that are 100 to 1000 times the "norm." Moreover, they surge and "pulse" with powerful energy spikes that can shoot well out into the environment ... beyond the "normal" distances......
Folks, the electrical industry knows this aspect well and has known it from the beginning ... even as they "cry" about "prudent avoidance" and the costs of having to "protect" the public from some of this risk.......
The kind of approach taken by the NCI study, of course, avoids any confrontation with this aspect ... just as they avoided any discussion of the "proximity" issue............
But, you will have noticed, they talked about the MONEY issue.....!!! Hardly any industry sponsored -- and the NCI study can be counted "industry sponsored" even though the funding funnels through a university and one of the rich "health" bureaucracies -- EMF study anymore fails to mention the "wasted" research that is being expended on the EMF matter........
NCI can't be very happy to see the money that is going into EMF research which they would much prefer to have passing through "their" funnels. They would like to be seen as the "controllers" of the spigot on all cancer research. But EMF is not JUST a cancer matter. Once you have recognized the extent of the possible health problems that result when the neuroendicrine system and the immune system are disturbed in the ways our researchers are finding, then you realize that it definitely is not just cancer that we can hope to make progress against!!! (Alzheimer's!!! Guru is not sure which part of the health system to identify with this already identified association....Dr. Sobel???)
That is their target, though!!!!!! Stop the research!!!! Both the electrical/telecommunications industries and the rich health "bureaucracy" see a common cause in stopping the EMF research. Go back and look at the tobacco health-issue history (or lead!!!), you will find that efforts to stop or curtail research spending was one of the tactics pursued -- along with, of course, BELITTLING the researchers efforts and results ... much like the papers tell us Dr. Edward W. Campion has done in the latest issue of the New England Journal of Medicine. (I have not yet seen his editorial, but it sounds VERY POLITICAL and not very scientific.....)
For some years these attempts to stymie research on the tobacco problem (and lead) were successful in those cases..... They will not be successful here..........
For one thing, folks, ... the rest of the world is getting wise to the EMF issue ... Wall Street (and America's rich health bureaucracies, largely funded by Wall Street) will not be totally in control......
The fault, as is often the case in science, is in assumptions made before the study began, assumptions upon which the study is based. If the assumptions can not be shown to be true, then the conclusions are not valid.
In their statistical study, it was assumed that the active agent in power line biological effects is the 60Hz sinusoidal wave. But there is substantial data and biological theory that indicate the primary active agent would be the transients that are found on power lines in varying forms to varying degrees in various places (Frey, 1994). A broad statistical study such as Linet et al's would tend to obscure such effects since data from areas where there are effective transients would be submerged in the mass of data from areas where there are not such transients.
Epidemiological studies, and statistical studies in general, are quite useful for hypothesis generation. But they are not appropriate for drawing conclusions. Causality can not be shown. There are just too many unknown and uncontrolled factors operating in a large statistical study, as compared to wet biological experiments. This is particularly the case with magnetic fields as an agent, for it is not yet clear what parameters of the agent are of importance biologically.
Is it appropriate to draw what may be life and death conclusions on the basis of one statistical study that is based on an assumption about what is the active agent, an assumption that can not be shown to be true? I doubt that many people would be willing to stake their life on one such study.
Frey points to the possibility of transients as the metric underlying the earlier correlations.
Another possibility is that the geomagnetic field may be a complementary factor, either because of cyclotron resonance or some other type of resonance interaction. In connection with this it appears that Denver was not one of the areas examined, which is puzzling considering the fact that data from the Denver vicinity was the impetus for such epidemiological studies.
The media has characterized this study as the largest yet. For some time, I have had the feeling that funding for such studies would continue until the funders got the answer they wanted. Never mind the original objections to the Wertheimer and Savitz results--that epidemiological studies were "innately non-scientific" and did not prove anything. Now that the results are more in line with what is desired, we are subjected to newspaper and TV reports saying that this report is the final word.
Nowhere does the media awaken the public to the fact that since Wertheimer's original 1979 results, there has arisen a wealth of (laboratory) evidence showing that ELF magnetic fields can have profound effects on living things. What in 1979 seemed inconceivable no longer appears improbable.
Perhaps now that we have had, in the words of the media, the "final word", the rest of us can get on with the science underlying these ELF interactions, and, through the science, determine the consequences for human hazard.
As a lab who believes that the electric component is more biologically important, we are not surprised that Dr Linet's study found no correation with measured magnetic fields and the disorder of interest although we note that if a 0.3microT cut-off point is used there appears to be a 1.8 elevation of risk).
The wire code configurations should however be a weak surrogate for electric fields, so these need a closer appraisal if our view of the importance of the electric field is to be supported. We are a little concerned to see that the distance from powerlines in the Linet study was limited to 150 feet (46 metres). There is a study by Ward et al. (1986) carried out by the UK National Grid showing that magnetic fields at over 100 metres distance from 400kV lines are still in excess of 0.2 microT, (and elsewhere the NGC indicates that at 100 metres the electric component may still exceed 30V/m).
This may have the effect in the Linet study of omitting a number of leukaemia cases and thereby biasing the results towards the nul hypothesis. Comments welcomed.
Such statements, based on a single study, are troubling. More disturbing still, is the fact that the data presented in the Linet study do not support the assertion that no link exists. Even a cursory review of the main data set shows a 53% increase in leukemia incidence at magnetic field exposure levels above 2 mG; a 72% increase (which is statistically significant) above 3 mG; and a more than 600% increase at exposures of between 4 and 5 mG. Above 5 mG, no link is shown, but there are too few cases in this range to yield any significant result.
Dr. Bary Wilson, who has co-authored a recent book on EMF and breast cancer, and several other speakers at the World Conference on Breast Cancer, including Dr. Kjell Hansson Mild of National Institute of Working Life in Sweden, have stated that a study which is apparently positive and limited only to leukemia should not be used to discount a possible link between EMF and cancer in its entirety.
Any statement claiming the demise of the EMF and cancer issue should be based on an analysis of all the available data and not one study, particularly one in which the reported data are apparently not reflected in the conclusions. In fact, available data on the subject, provided by many scientists over more than a decade, do not support the hypothesis that there is no link between EMF exposure and increased risk for several types of cancer.
Cindy Sage of Sage Associates and Chair of the EMF program at the conference points out that, "even a small increased risk of breast cancer due to EMF exposure has enormous public health implications given the high incidence of this disease in developed countries."
Based on the Linet, et al. study, it is clearly not justified to call for the end of research into the possible !ink between EMF and cancer. Given the growing body of evidence for a possible link between EMF and breast cancer, in particular, cessation of research funding at this time would be reckless and scientifically indefensible.
Bary W. Wilson, Ph.D.
Pacific Northwest National Laboratory, USA
Yet the NCI's own data show an increased leukemia risk at EMF levels found in about 5% of U.S. homes. On the job, workers are often exposed to levels many times higher. Is the NCI willing to tell these people that they are safe?
In a word, no. Dr. Robert Tarone of the NCI conceded that, "We cannot say that there is nothing going on at higher exposure levels." Yet the NCI is not discouraging anyone from sounding the "all clear."
The NCI's results actually show that children exposed to more than 3 mG face a 72% increase in leukemia risk. Many other epidemiologists believe that this study provides evidence for an EMF effect. But you'd never know this from the NCI's press release.
How did the NCI arrive at a conclusion that seems at odds with its own data? First, there is the question of statistical significance. The researchers found a higher risk above 2 mG and indications of a dose-response relationship. But these results were not statistically significant, meaning that they could have happened by chance more than 5% of the time.
This is an important point-but no one should forget that the definition of "statistical significance" is a rule of thumb, not a law of nature. A finding with a significance level of 4% could still turn out to be due to chance. And one with a significance level of 10% could still reflect a real association.
Epidemiologists are arguing about whether the NCI team used the right kind of test to look for a dose-response relationship (see p.11). Regardless of who is right, the numbers tell us basically the same thing: There is some evidence of a dose-response relationship, but it is not conclusive.
The data that show a higher risk above 3 mG are statistically significant-but the NCI researchers discount this finding for another reason. The a priori hypothesis they had decided to test was that a child's leukemia risk would increase with exposures above 2 mG.
The use of a priori hypotheses has been adopted by epidemiologists for important reasons. It is a way for researchers to keep themselves honest since, if enough different comparisons are done, some false-positive findings will emerge due to chance. But it was never meant to be dogma.
The Chasm Between 2-3 mG and 1,000 mG
The selection of 2 mG rather than 3 as the cutoff point was somewhat arbitrary. Current international standards allow exposures up to 1,000 mG for children and 5,000 mG for workers. In this context, the difference between 2 and 3 mG almost seems a nonissue.
Had 3 mG been chosen instead, the headlines would have told a completely different story. As a post hoc finding, it is only limited evidence of a higher risk-but why is the NCI holding it up as evidence that there is no danger at all?
Epidemiologists have recently come under fire for acting as accomplices of an alarmist media in needlessly stirring public fears. But if epidemiologists need to take some responsibility for the headlines prompted by their studies, this has to cut both ways. When a study that suggests some risk leads to news reports that there is no danger, science is not well served. In this case, being too conservative in the interpretation of data is not an act of caution-rather, it leads to a reckless indifference to public health.
Millions of people live in the 5% of U.S. homes with EMFs above 3 mG. Add in the power company employees, telephone workers, sewing machine operators and others who routinely experience even higher exposures, and it is clear that a huge number of people are potentially at risk.
The NCI's Dr. Martha Linet has acknowledged that her conclusions are at odds with those of three previous studies. It is worth noting that none of the investigators in those studies feels that the NCI study is the last word. In fact, all three-Drs. Stephanie London, David Savitz and Nancy Wertheimer-feel that the NCI's results are either ambiguous or show a cancer link. And, in fact, the risks uncovered by the NCI are consistent with the range found in earlier investigations, and the weight of the evidence still favors an association between EMFs and leukemia in children.
But the New England Journal of Medicine is in a hurry to toss all these studies aside. Dr. Edward Campion's editorial asserts that "the better epidemiologic studies, including that by Linet," support the conclusion of no risk. These "better studies" are not identified, and what makes them better is not defined-unless it is the fact that Campion agrees with their conclusion. The Journal does not stop there. It goes on to declare that "it is time to stop wasting our research resources" on EMF health research. In an interview, Campion said he saw no distinction between studies of residential EMFs and on-the-job exposures.
Never mind the higher risk ratios found in occupational cancer studies. Never mind the links to Alzheimer's disease, Lou Gehrig's disease, brain tumors and breast cancer. The Journal views any interest in the health effects of non-ionizing radiation as essentially without scientific foundation, blaming "activists and the media" for concerns about "microwave appliances, radar, VDTs, and even cellular telephones."
It is this kind of overreaching that betrays an ideological agenda. But sweeping statements will not make the EMF issue go away. Too many facts already litter the scientific landscape, and their number continues to grow. In this issue alone, we report on three new epidemiological studies pointing to health risks posed by EMFs, including a German study that contradicts the NCI's conclusions.
The issue of EMFs and human health is an unsolved puzzle. All the pieces do not fit together neatly, and that, of course, is frustrating. But the correct response to a frustrating puzzle is not to dump all the pieces on the floor, as Campion does.
The media have little tolerance for uncertainty. But good science requires dealing with uncertainty every day-having your curiosity spurred on by what you do not know, while avoiding a rush to judgment. It is unfortunate when national scientific and medical institutions, like the New England Journal and the NCI, show as little tolerance for uncertainty as the television news.
Table 2 of the paper contains: Magnetic-Field Level (mG) No. Of Case Patients <0.65 267 0.65-0.99 123 1.00-1.99 151 =>2.00 83The median magnetic-field level for these 624 cases can not be determined from the table. Inquiries to Martha S. Linet at the National Cancer Institute remain unanswered.
A Freedom of Information action was filed on May 7, 1999, asking for the precise magnetic-field level of these 624 cases. The action lay dormant until United States Senator Tim Hutchinson interceded on August 23, 1999. The requested data arrived on November 27, 1999. What follows was made possible by Senator Hutchinson's intervention and sincere thanks are extended to him.
Let us be clear about the term median. Webster's Collegiate Dictionary defines median as, "Designating a point so chosen in a series that half of the individuals in the series are on one side of it, and half on the other." If one knew the median of the leukemia victims homes and this median proved to be the same as that of homes all across the nation one could affirm that there is indeed no evidence that 60 Hertz magnetic fields are causal to childhood leukemia.
The national median was determined by the Electric Power Research Institute in 1993, as follows:
Table S-6 Spot Measurements and Combined Power Line/Grounding System Fields Median Spot Median Combined Field Measurement Power Line/Grounding System (992 residences) (986 residences) Values exceeded in (mG) (mG) 50% of the residences 0.5 0.5 25% of the residences 1.0 1.0 10% of the residences 1.7 1.8 5% of the residences 2.6 2.5 1% of the residences 5.8 5.5from EPRI TR-102759-V2 Project 3335-02 Final Report September 1993 Page S-18 Half of the 992 homes having time-weighted values at or under 0.5 mG satisfies the definition of the term median. However, the table's resolution is only to 0.1 mG. Thus, 0.5 mG could be anything between 0.45 and 0.55 mG. Accordingly, in the calculations below, 0.55 mG will be taken as national median, thus giving the Linet study the best possible comparative figure.
The raw data from the NCI was computer sorted in terms of ascending time- weighted average. This table is appended below. Here one may find:
311 0.073 NJ 312 0.074 IL 313 0.076 MICase # 312, at the middle of the 624 total number, had a time-weighted average of 0.74 mG (the table being in microtesla) and was from Illinois.
The preceding case from New Jersey was 0.01 mG lower and the succeeding case from Michigan was 0.02 mG higher.
Clearly, the 0.74 median of Linet's 624 cases is significantly higher than the 0.55 median of EPRI's 992 homes. Could chance alone account for this difference? If so, how likely is it that chance rather than elevated time-weighted magnetic fields produced these results?
Christoph Reuss, a Swiss mathematician, in a June 14, 1998, email message wrote, "The probability of 267 or less heads appearing after a basket of 624 coins was overturned is:
P [H<=267] = 1/2^624 * SUM(k=0..267) (624! / (624-k)! / k!) = 0.0001795451715 = 1/5569.629033"Professor John Clark, a now retired mathematician who taught computer science at Orange Coast College, wrote a computer program in PASCAL. It performs the equation conveyed by Christoph Reuss. This equation solves the question posed in the preceding paragraph.
Since the 60 Hertz magnetic field median is higher than that of the EPRI median one needs to determine how many leukemia cases occurred in homes at or below the EPRI median of 0.55 mG discussed above. If one returns to the sorted table one finds that there were 219 cases under 0.56 mG (0.056 æT). What is the probability that chance alone would place only 219 out of 624 cases on one side of the median when approximately 312 would be expected? Here is the computed solution as seen on the computer screen.
Please enter your Total Case number now 624 Please enter your Questioned Case number now 219 The results are NUMERATOR = 2.99006405675314E+0174 DENOMINATOR = 6.96173189944793E+0187 QUOTIENT = 4.29500029581757E-0014 RECIPROCAL = 2.32828854743920E+0013 The probability of chance yielding 219 or less Questioned Cases out of 624 Total Cases is one in 23,282,885,474,392.The Linet raw data reveals a 23,282,885,474,392 to one probability that elevated 60 Hz time-weighted 60 Hertz magnetic fields are in some manner causal to childhood acute lymphoblastic leukemia.
This analysis is strengthened by noting the similarities of the EPRI study to that of Linet at the NCI. Both used time-weighted averages. The NCI study had cases from eleven states, Iowa, Illinois, Indiana, Massachusetts, Michigan, Minnesota, New Jersey, New York, Ohio, Pennsylvania, and Wisconsin. The EPRI study does not list states but instead provides the names of the twenty-two electric utilities which participated in gathering the data. A preliminary internet study of these companies shows that their evaluated residences would have been in all these states save Indiana (Linet study had 41 IN cases). Accordingly, the median values for these residences and those of the NCI would be expected to be quite close if 60 Hertz magnetic fields were in no way causal to childhood leukemia. But they are not!
What is the remedy? One might begin by applying the physics known to Michael Faraday more than a century ago. Supply and return currents should be kept in close proximity so that their magnetic fields cancel. Instead, the WYE distribution system in our country conducts return currents on water gas and sewer pipes, on metal sheaths of TV and telephone cables, and on any other metallic path available.
Legislation to restrict electric power delivery to a power company's lines would go a long way toward reducing 60 Hertz magnetic fields in homes and working environments.
This writer wishes to again express his gratitude to Senator Tim Hutchinson for fostering the delivery of the Linet raw data. Without that data this could not have been written.
SORTED RAW DATA TABLE1 0.017 IA 2 0.019 IN 3 0.019 IL 4 0.020 MN 5 0.020 IA 6 0.020 PA 7 0.021 MN 8 0.021 WI 9 0.021 MN 10 0.021 MN 11 0.022 MI 12 0.022 MI 13 0.022 OH 14 0.023 NJ 15 0.024 IL 16 0.024 IA 17 0.024 OH 18 0.024 MI 19 0.025 NJ 20 0.025 IA 21 0.025 MI 22 0.025 PA 23 0.025 MN 24 0.025 MN 25 0.026 PA 26 0.026 MI 27 0.026 MN 28 0.026 MI 29 0.026 IA 30 0.027 OH 31 0.027 PA 32 0.027 MI 33 0.028 NJ 34 0.028 IA 35 0.029 PA 36 0.029 IN 37 0.029 NJ 38 0.029 OH 39 0.029 IL 40 0.030 IL 41 0.030 OH 42 0.030 MI 43 0.030 IA 44 0.030 MI 45 0.031 IN 46 0.031 MN 47 0.031 MN 48 0.031 PA 49 0.031 OH 50 0.031 MN 51 0.031 IL 52 0.032 OH 53 0.032 MI 54 0.032 OH 55 0.032 PA 56 0.032 PA 57 0.032 OH 58 0.032 PA 59 0.032 PA 60 0.032 PA 61 0.032 OH 62 0.033 MI 63 0.033 MI 64 0.033 IA 65 0.033 NJ 66 0.033 MN 67 0.033 MN 68 0.034 MN 69 0.034 PA 70 0.034 NJ 71 0.034 OH 72 0.034 IA 73 0.034 IN 74 0.035 IN 75 0.035 IN 76 0.035 MN 77 0.035 OH 78 0.036 MI 79 0.036 IA 80 0.036 IA 81 0.036 MI 82 0.036 OH 83 0.036 NJ 84 0.036 IL 85 0.036 PA 86 0.036 NJ 87 0.036 IL 88 0.037 IA 89 0.037 MN 90 0.038 IN 91 0.038 MI 92 0.038 OH 93 0.038 OH 94 0.038 PA 95 0.038 OH 96 0.038 NJ 97 0.038 NJ 98 0.038 NJ 99 0.038 NY 100 0.038 NJ 101 0.038 PA 102 0.038 IN 103 0.038 OH 104 0.038 PA 105 0.039 PA 106 0.039 MN 107 0.039 MI 108 0.039 MN 109 0.039 IN 110 0.039 IL 111 0.039 MI 112 0.040 IL 113 0.040 MI 114 0.040 NJ 115 0.040 IL 116 0.040 PA 117 0.040 MN 118 0.040 NJ 119 0.040 MN 120 0.041 MI 121 0.041 PA 122 0.041 IN 123 0.041 OH 124 0.041 MI 125 0.041 IL 126 0.041 OH 127 0.041 IN 128 0.041 MN 129 0.042 OH 130 0.042 NJ 131 0.042 WI 132 0.042 MN 133 0.042 IA 134 0.042 IN 135 0.042 PA 136 0.042 MI 137 0.042 OH 138 0.043 NJ 139 0.043 PA 140 0.043 PA 141 0.043 OH 142 0.043 MI 143 0.043 PA 144 0.043 OH 145 0.043 OH 146 0.043 IA 147 0.044 IA 148 0.044 MI 149 0.044 PA 150 0.044 OH 151 0.044 MN 152 0.044 PA 153 0.045 OH 154 0.045 IN 155 0.045 MI 156 0.045 NJ 157 0.045 IL 158 0.046 MI 159 0.046 PA 160 0.046 IN 161 0.046 MN 162 0.046 IA 163 0.046 NJ 164 0.047 IN 165 0.047 PA 166 0.047 OH 167 0.047 PA 168 0.047 IA 169 0.047 NJ 170 0.047 IA 171 0.047 MN 172 0.047 IA 173 0.047 OH 174 0.047 MI 175 0.047 IL 176 0.048 PA 177 0.049 OH 178 0.049 OH 179 0.049 WI 180 0.050 MI 181 0.050 IL 182 0.050 OH 183 0.050 PA 184 0.050 IL 185 0.050 NJ 186 0.050 IA 187 0.050 IA 188 0.050 OH 189 0.051 NJ 190 0.051 OH 191 0.051 MN 192 0.051 MN 193 0.051 OH 194 0.052 MI 195 0.052 MI 196 0.052 IL 197 0.052 OH 198 0.053 IN 199 0.053 MN 200 0.054 MN 201 0.054 PA 202 0.054 PA 203 0.054 NJ 204 0.054 MI 205 0.054 WI 206 0.054 IL 207 0.054 NJ 208 0.054 IN 209 0.054 OH 210 0.054 IL 211 0.055 OH 212 0.055 NJ 213 0.055 IL 214 0.055 IA 215 0.055 MI 216 0.055 NJ 217 0.055 PA 218 0.055 PA 219 0.055 OH 220 0.056 MI 221 0.056 PA 222 0.056 MA 223 0.056 NJ 224 0.056 PA 225 0.056 MI 226 0.056 OH 227 0.056 IL 228 0.058 PA 229 0.058 OH 230 0.058 MN 231 0.058 OH 232 0.059 IL 233 0.059 PA 234 0.059 MN 235 0.059 NJ 236 0.059 PA 237 0.059 PA 238 0.059 MI 239 0.059 MN 240 0.059 MN 241 0.060 PA 242 0.060 MN 243 0.060 PA 244 0.060 PA 245 0.060 PA 246 0.061 NJ 247 0.061 PA 248 0.061 OH 249 0.061 IL 250 0.062 MN 251 0.062 MI 252 0.062 PA 253 0.062 NJ 254 0.062 MI 255 0.062 OH 256 0.063 OH 257 0.063 OH 258 0.063 IN 259 0.063 IN 260 0.064 WI 261 0.064 NJ 262 0.064 PA 263 0.064 IA 264 0.064 PA 265 0.064 PA 266 0.065 OH 267 0.065 MN 268 0.065 MI 269 0.066 OH 270 0.066 OH 271 0.066 PA 272 0.066 PA 273 0.066 PA 274 0.067 NJ 275 0.067 OH 276 0.067 NJ 277 0.067 MI 278 0.067 MI 279 0.068 NJ 280 0.068 PA 281 0.068 MN 282 0.068 IA 283 0.069 MI 284 0.069 NJ 285 0.069 MI 286 0.069 IL 287 0.070 PA 288 0.070 IL 289 0.070 OH 290 0.070 OH 291 0.070 IA 292 0.071 PA 293 0.071 OH 294 0.071 MN 295 0.071 MN 296 0.071 OH 297 0.071 IL 298 0.072 OH 299 0.072 IA 300 0.072 OH 301 0.072 PA 302 0.072 PA 303 0.072 PA 304 0.073 OH 305 0.073 IA 306 0.073 NJ 307 0.073 NJ 308 0.073 NJ 309 0.074 PA 310 0.074 IL 311 0.074 MI 312 0.074 IL 313 0.075 PA 314 0.075 OH 315 0.075 IA 316 0.076 NJ 317 0.076 MI 318 0.076 OH 319 0.076 IL 320 0.076 OH 321 0.077 IN 322 0.077 NJ 323 0.078 IN 324 0.078 PA 325 0.078 MN 326 0.080 PA 327 0.080 MI 328 0.080 IL 329 0.080 OH 330 0.081 MI 331 0.081 IL 332 0.082 IA 333 0.082 PA 334 0.082 IN 335 0.082 OH 336 0.083 PA 337 0.083 PA 338 0.083 OH 339 0.083 MN 340 0.083 IL 341 0.085 PA 342 0.085 MI 343 0.085 OH 344 0.085 MI 345 0.085 IA 346 0.085 OH 347 0.085 MN 348 0.086 OH 349 0.086 IA 350 0.086 OH 351 0.086 PA 352 0.086 MN 353 0.087 IN 354 0.087 PA 355 0.087 OH 356 0.087 PA 357 0.088 OH 358 0.088 IA 359 0.088 PA 360 0.088 OH 361 0.089 PA 362 0.089 MI 363 0.089 MI 364 0.091 IL 365 0.092 MN 366 0.092 NY 367 0.092 MN 368 0.092 OH 369 0.093 OH 370 0.093 NJ 371 0.094 PA 372 0.094 OH 373 0.095 PA 374 0.095 IL 375 0.095 MI 376 0.095 PA 377 0.096 PA 378 0.096 IL 379 0.096 IN 380 0.096 PA 381 0.096 MN 382 0.097 IA 383 0.097 PA 384 0.097 MN 385 0.098 MI 386 0.098 OH 387 0.098 OH 388 0.099 PA 389 0.099 MI 390 0.099 IL 391 0.100 IL 392 0.100 MN 393 0.100 IN 394 0.101 MI 395 0.101 MN 396 0.102 IA 397 0.102 OH 398 0.103 IA 399 0.103 IL 400 0.103 IN 401 0.103 OH 402 0.103 OH 403 0.104 NJ 404 0.104 PA 405 0.105 MI 406 0.106 PA 407 0.106 MI 408 0.106 OH 409 0.107 OH 410 0.107 PA 411 0.107 OH 412 0.108 IL 413 0.109 NJ 414 0.109 MN 415 0.110 NJ 416 0.111 MI 417 0.111 MN 418 0.112 NJ 419 0.112 NJ 420 0.112 IN 421 0.112 PA 422 0.113 PA 423 0.113 PA 424 0.114 NJ 425 0.114 OH 426 0.114 PA 427 0.114 OH 428 0.114 IL 429 0.115 IL 430 0.115 MI 431 0.116 NJ 432 0.116 NJ 433 0.116 IA 434 0.117 MN 435 0.117 NJ 436 0.118 MN 437 0.118 NJ 438 0.118 IN 439 0.118 MN 440 0.119 OH 441 0.119 PA 442 0.120 MN 443 0.120 MI 444 0.121 OH 445 0.121 MI 446 0.121 NJ 447 0.121 IL 448 0.122 OH 449 0.122 NJ 450 0.122 IN 451 0.122 MN 452 0.123 IA 453 0.124 NJ 454 0.125 MN 455 0.125 IL 456 0.125 PA 457 0.125 MN 458 0.125 NJ 459 0.126 PA 460 0.127 OH 461 0.127 MI 462 0.127 MN 463 0.127 MI 464 0.128 NJ 465 0.129 PA 466 0.129 MI 467 0.129 OH 468 0.129 MN 469 0.130 OH 470 0.132 MN 471 0.132 NJ 472 0.132 NJ 473 0.133 MI 474 0.133 MN 475 0.135 OH 476 0.135 PA 477 0.135 PA 478 0.135 MI 479 0.136 OH 480 0.136 IL 481 0.137 IL 482 0.142 OH 483 0.143 MN 484 0.145 MI 485 0.145 PA 486 0.145 PA 487 0.146 IA 488 0.146 MI 489 0.146 NJ 490 0.147 OH 491 0.147 MI 492 0.147 MI 493 0.147 NJ 494 0.148 MI 495 0.149 OH 496 0.153 PA 497 0.154 IL 498 0.154 MN 499 0.155 MI 500 0.155 MN 501 0.156 OH 502 0.158 IL 503 0.158 PA 504 0.158 MI 505 0.159 PA 506 0.159 IA 507 0.159 IN 508 0.161 PA 509 0.163 IL 510 0.164 MI 511 0.166 IN 512 0.167 IA 513 0.167 PA 514 0.168 IL 515 0.169 IL 516 0.169 IA 517 0.169 MI 518 0.170 IL 519 0.170 PA 520 0.171 OH 521 0.171 IN 522 0.171 MI 523 0.172 MI 524 0.174 NY 525 0.177 PA 526 0.179 PA 527 0.181 IN 528 0.182 PA 529 0.182 MN 530 0.182 IL 531 0.183 IN 532 0.188 PA 533 0.188 PA 534 0.190 PA 535 0.191 MI 536 0.191 MI 537 0.191 OH 538 0.193 NJ 539 0.194 PA 540 0.194 PA 541 0.195 IL 542 0.200 OH 543 0.202 OH 544 0.203 MN 545 0.203 MN 546 0.203 OH 547 0.203 MI 548 0.207 MN 549 0.209 OH 550 0.213 NJ 551 0.213 IL 552 0.215 NJ 553 0.216 IA 554 0.216 OH 555 0.221 MN 556 0.224 IN 557 0.226 OH 558 0.229 IL 559 0.229 PA 560 0.230 NJ 561 0.230 OH 562 0.231 OH 563 0.237 IL 564 0.240 OH 565 0.242 PA 566 0.245 OH 567 0.250 PA 568 0.252 OH 569 0.253 IL 570 0.256 NJ 571 0.256 IL 572 0.258 PA 573 0.261 MN 574 0.265 MI 575 0.265 PA 576 0.268 OH 577 0.282 IL 578 0.284 IL 579 0.285 MN 580 0.300 PA 581 0.300 IN 582 0.300 OH 583 0.304 PA 584 0.304 OH 585 0.315 NJ 586 0.316 PA 587 0.316 OH 588 0.316 OH 589 0.324 OH 590 0.326 PA 591 0.328 IA 592 0.334 MI 593 0.337 IA 594 0.341 OH 595 0.350 IL 596 0.353 IN 597 0.373 IN 598 0.376 OH 599 0.389 PA 600 0.392 OH 601 0.399 IA 602 0.400 IN 603 0.402 OH 604 0.406 PA 605 0.415 PA 606 0.417 OH 607 0.432 OH 608 0.439 IA 609 0.439 IA 610 0.448 PA 611 0.458 MN 612 0.476 PA 613 0.477 MN 614 0.477 MI 615 0.490 IN 616 0.508 OH 617 0.524 PA 618 0.530 MN 619 0.548 OH 620 0.564 PA 621 0.636 PA 622 1.000 IN 623 1.018 IL 624 1.064 MN