Scientific Methodology for Assessing Public Health Issues: A Case Study of EMF

1. Harlem Children Society – Mentoring Lecture July 27, 2006 Scientific Methodology for Assessing Public Health Issues: A Case Study of EMF William H. Bailey, Ph.D.Principal Scientist

2. “The Scientific Method” The scientific method is the process by which scientists, collectively and over time, endeavor to construct an accurate representation of the world.

3. Steps in the Scientific Method • Observation and description of a phenomena • Formulation of an hypothesis to explain the phenomena • Use of the hypothesis to predict the existence of other phenomena • Experimental tests of the predictions by several independent experimenters and properly performed experiments

4. Flow diagram describing the scientific method

5. The Scientific Method (con’t) • Observe some aspect of the universe • Invent a tentative description, called a hypothesis, that is consistent with what you have observed • Use the hypothesis to make predictions • Test those predictions by experiments or further observations and modify the hypothesis in the light of your results • Repeat steps 3 and 4 until there are no discrepancies between theory and experiment and/or observation • STEPS 4 and 5 REQUIRE INTERPRETATION

6. Origin and modification of the EMF Hypothesis Observation It seems as if children with cancer live near pole-mounted transformers on utility distribution lines Hypothesis Something about distribution lines increases the risk of cancer in children Prediction Children who live near power lines will have a higher rate of cancer than those who do not Tests Expose laboratory animals and cells. Compare exposures of cancer cases and controls

7. What is there about power lines that we can measure and study? • Wertheimer & Leeper (1979) considered 3 exposures • PCBs in pole transformers • EMFs from distribution lines and other electrical facilities • Air pollution (because they observed that large 3-phase distribution lines are frequently located located along heavily traveled roads)

8. Power Lines and EMF • Power lines produce electric and magnetic fields (EMF) • Electricity produces EMF that changes direction and intensity 60 times per second – a frequency of 60 Hertz (Hz) • EMF are produced by other sources that surround us in our daily lives

9. EMF Spectrum Source: NIEHS, 2002

10. Electric Fields • Electric fields result from voltages • Measured in units of volts per meter (V/m) or kilovolts per meter (kV/m) • 1000 V = 1 kV • Shielded from objects such as trees, shrubs, and walls • Strength diminishes as you move away from the source

11. Magnetic Fields • Magnetic fields result from current flow • Measured in gauss (G) or milligauss (mG) or microtesla (µT) • 1000 mG = 1G = 100 µT • Not shielded from objects such as trees, shrubs, walls • Strength diminishes as you move away from the source

12. Source: NIEHS, 2002

13. Magnetic Fields in Everyday Life

14. Modifying the Hypothesis Developments in Science • Evidence stronger for magnetic than electric fields • Methods to calculate fields from power lines • Personal ‘dosimeters’ developed • Studies show no consistent link with childhood brain cancer

15. Personal Dosimeter

16. How Do Scientists Evaluate Potential Risks of Exposure? • Epidemiologic observations • Laboratory studies in animals • Laboratory studies in cells and tissue

17. Epidemiology • Compares characteristics of people with and without a disease • Statistical associations between people and exposure • Observational, not experimental • Strength: Studies people

18. Epidemiology • Observational research • Includes scientificmethod for assessing causality The study of factors that cause disease or influence health in the human population

19. An Example of Association Gambling Cancer • Cancer occurrence was found to be greater people who gamble than in comparison populations • Gambling is associated with cancer

20. The Association is Indirect Gambling Cancer Alcohol/Smoking Consumption In this example, alcohol consumption and smoking are confounding factors

21. Interpretation of Relative Risk (RR) • If disease rate, or risk, is the same in both groups, then RR will be 1.0 • Interpreted as “no association” • If disease rate (risk) is greater in exposed population, then RR will be > 1 • Interpreted as a positive association with the disease

22. Cases Controls

23. Case-Control Study Design Base Population No Disease Disease Non-exposed (C) Non-exposed (D) Exposed (A) Exposed (B)

24. Association of Childhood Leukemia with 48-hr Personal Exposure Source: McBride et al. 1999

25. Interpreting Data Are observed results due do Confounding? Chance? Bias?

26. Individual Characteristics That Modify the Effect of Environmental Factors Gender Age Physical condition Behavior Genetic factors Nutrition Disease

27. Judging Whether an Association is Causal • Strength - Is it strong or weak? • Consistency • Dose- response • Correct timing • Biological plausibility • Experimental evidence

28. Hundreds (and Hundreds) of Studies Conducted in Past 30 Years • Epidemiology (Observational) Studies • Some residential studies have reported statistical associations between magnetic field exposure and some types of cancer • This prompted additional research • All studies are not equal! • The larger and more reliable studies have not found these associations

29. Polling Prediction Error in 1948 Presidential Election

30. Examples of Scientific Method ‘Failures’ - Epidemiology • Prediction of Dewey win over Truman in 1948 US presidential election • Association between use of VDTs and miscarriage in California • Association of childhood leukemia with EMF and selection/response bias • Non-failure – Magnesium sulfate and heart attack

31. Experimental Studies of EMF Exposure and Health Laboratory (animals) Laboratory(cells and tissues) Experimental science — control over relevant variables

32. Exposed Group EMF Temperature = Humidity = Genetics = Age = History = Health status = Control Group No EMF Temperature Humidity Genetics Age History Health status Typical Experimental Design-Subjects randomly assigned to:

33. Examples of Scientific Method ‘Failures’ – Experimental studies • Mortality of young rats and mice • Damage to DNA • Calcium uptake by white blood cells • Melatonin hormone levels in rats • Non-failure - Stress-induced heart damage • Malformations in chicken eggs • Metabolic changes in marine cells

34. Hundreds (and Hundreds) of Studies Conducted in Past 30 Years (con’t) • Experimental Studies • Laboratory animals exposed to high levels of magnetic fields for their entire lifespan had no increase in cancer overall, or types of cancer statistically linked with EMF sources in some epidemiology studies • EMF does not damage cells like known cancer-causing agents • Weight-of-the-Evidence Reviews

35. Weight-of-the-Evidence • The data must present a logically consistent and coherent picture • Underlying concepts • Things that cause cancer in animals tend to cause cancer in humans • Cells exposed to cancer-causing agents show typical changes • “The dose makes the poison” • Systematic methods must be used to limit misconceptions

36. Interpreting Results • All studies are not equal • Association is not causation • Research is evaluated in context

37. Science, Slogans and Civic Duty– Donald N. Langenberg “When the time comes to move from debate to action, action is shaped by the perceptions and values of the leaders of the debate. Sometimes these perceptions and values reflect the relevant body of scientific knowledge, and sometimes they do not.” Science, 252:361-363, 1991

38. Scientific Reviews of EMF Research by National/International Organizations • Large panels, balanced composition • Experts in multiple disciplines • Defined methodology • Conclusions represent a consensus

39. Other Scientific Reviews Potential issues as to: • Overweighting of extreme views • ‘Missing’ expertise in one or more disciplines • Ad hoc approach and unfamiliarity with risk assessment • Conclusions may be biased towards views of one or two persons

40. International and National Scientific Review Groups • National Institute of Environmental Health Sciences (NIEHS) • U.S. National Academy of Sciences (NAS) • International Agency for Research in Cancer (IARC) • National Radiological Protection Board of Great Britain (NRPB) • Health Council of the Netherlands (HCN) • World Health Organization (WHO)

41. Federal-Provincial-Territorial Radiation Protection Committee- Canada (2005) • Established to support government radiation protection agencies in Canada • Review of epidemiology and laboratory research regarding 60-Hz EMF • Conclusion • “Adverse health effects from exposure to power-frequency EMFs, at levels normally encountered in homes, schools and offices, have not been established.” • “Since there is no conclusive evidence that exposure to EMFs at levels normally found in Canadian living and working environments is harmful, FPTRCP is of the opinion that moderate measures and participation in the process of acquiring new knowledge are sufficient.”

42. What are the Views ofScientific Review Panels? • They agree that there is little evidence suggesting that EMF is associated with adverse health effects • They believe that there is some epidemiological evidence that EMF at high exposures is linked to childhood leukemia • They agree that the laboratory data does not support a link between EMF and any adverse health effect, including leukemia • They have not concluded that EMF is known to cause any disease