Lima, Peru March 7, 2001 EMF Epidemiology: State of the Science Richard Tell Associates, Inc. Las Vegas, NV Leeka I. Kheifets, Ph.D. Technical Executive & EMF Area Manager Types of Epidemiologic Studies of Exposure Residential Wire code Measurements Occupational Appliance use Peru EMF Epi LIK 03_01.2
The Questions Driving the issue: leukemia and brain cancer New: breast cancer, neurodegenerative and heart disease Almost not a question: reproductive outcomes CDHS studies? Peru EMF Epi LIK 03_01.3 Pooled Analyses of Childhood Leukemia Greenland et al., Epidemiology, 2000 12 studies with fields; 4 with wire codes Not including UK study Field studies: 2,656 cases; 7,084 controls Metric of choice: time-weighted average Ahlbom et al., British J. Cancer, 2000 9 studies with fields; 2 with wire codes Including UK study Field studies: 3,247 cases; 10,400 controls Metric of choice: geometric mean Peru EMF Epi LIK 03_01.4
Results: Greenland et al., 2000 3.0 Odds Ratio (±95% CI) 2.5 2.0 1.5 1.0 0.5 Peru EMF Epi LIK 03_01.5 cases/controls 318/529 2,145/6,275 94/150 99/130 <1 >1-2 >2-3 >3 Magnetic Field (mg) Results: Ahlbom et al., 2000 3.5 Odds Ratio (±95% CI) 3.0 2.5 2.0 1.5 1.0 0.5 Peru EMF Epi LIK 03_01.6 cases/controls 44/62 104/147 233/332 2,866/9,859 <1 1-2 2-4 >4 Magnetic Field (mg)
Measured Fields & Leukemia Summary OR 0.1µT (ref.) Without covariate adjusment >0.1µT, 0.2µT Woolf 1.00 1.00 (0.82 1.21) Mantel-Haenszel 1.00 0.98 (0.82 1.19) Spline 1.00 1.04 (0.93 1.17) With covariate adjustment >0.2µT, 0.3µT 0.98 (0.68 1.40) 0.96 (0.67 1.36) 1.21 (1.02 1.43) >0.3µT 1.91 (1.37 2.67) 1.69 (1.21 2.35) 1.83 (1.14 2.93) Woolf 1.00 1.08 (0.87 1.35) Mantel-Haenszel 1.00 1.03 (0.81 1.31) 0.97 (0.65 1.44) 0.87 (0.55 1.37) 2.14 (1.49 3.08) 2.22 (1.48 3.34) Greenland et al., 2000 Peru EMF Epi LIK 03_01.7 Pooled Analysis of Childhood Leukemia Studies Exposure Relative Risks (95% Confidence Intervals) Measurement Calculated Fields All Studies <0.1 µt 1.00 1.00 1.00 0.1-0.2 µt 1.05 (0.9-1.3) 1.58 (0.8-3.3) 1.08 (0.9-1.3) 0.2-0.4 µt 1.15 (0.9-1.5) 0.79 (0.3-2.3) 1.11 (0.8-1.5) >0.4 µt 1.87 (1.1-3.2) 2.13 (0.9-4.9) 2.00 (1.3-3.1) Ahlbom et al., 2000 Peru EMF Epi LIK 03_01.8
German Childhood Leukemia Study Results <0.1 µt 0.1 to <0.2 µt 0.2 to <0.4 µt 0.4 µt Median 24h MF Cases 472 33 6 3 Controls 1210 73 15 3 Adjusted odds ratios* 1.00 1.15 (0.73-1.81) 1.16 (0.43-3.11) 5.81(0.78-43.2) Median Nighttime MF Cases 468 34 7 5 Controls 1219 70 8 4 Adjusted odds ratios* 1.00 1.42 (0.90-2.23) 2.53 (0.86-7.46) 5.53 (1.15-26.6) N.B. Pooled analyses including cases from two previous German studies gave similar results Schuz et al., Int. J. Cancer 2001 Peru EMF Epi LIK 03_01.9 Childhood Leukemia Summary Childhood leukemia main driver in risk assessments Recent pooling efforts point to risk at 0.3-0.4+µT Animal studies negative Ongoing studies Germany, Italy, Japan, U.S., UK Research needs: High-exposure studies Contact currents Population mixing Transients Selection bias Peru EMF Epi LIK 03_01.10
Occupational Leukemia Meta-Analysis Pooled & Individual Risk Estimates for 38 Leukemia Studies Risk Estimate Kheifets et al. JOEM, 1997 Peru EMF Epi LIK 03_01.11 Year of Publication Occupational Brain Cancer Meta-Analysis Pooled & Individual Risk Estimates for 29 Brain Cancer Studies Relative Risk Kheifets et al. JOEM, 1995 Peru EMF Epi LIK 03_01.12 Year of Publication
Occupational Brain Cancer Meta-Analysis Pooled Risk Estimates for Each Year Cumulative Pooled Relative Risk Kheifets et al. JOEM, 1995 Peru EMF Epi LIK 03_01.13 Year of Publication Occupational Leukemia & Brain Cancer Small risk at the limit of detection Few to no studies under way Research needs: Exposure assessment based on job and environment Electric fields Combining residential and occupational exposure Contact current exposure assessment Peru EMF Epi LIK 03_01.14
Breast Cancer Major women s health (& public health) issue Tied (rightfully or wrongfully) to EMF, based mainly on prior laboratory research Hypothesis-based Epidemiologic studies largely negative None designed to test the hypothesis Peru EMF Epi LIK 03_01.15?? EMF! Melatonin" Cancer! Cardiovascular Disease: Lines of Evidence Magnetic Field Human Lab (overnight) +/- +++ HRV Epidemiology (+/?) (years decades) Clinical/ Epidemiology 1985 99 CV Risk Peru EMF Epi LIK 03_01.16
Cardiovascular Disease Association with acute mortality reported in one study HRV reduction in laboratory setting apparently inconsistent Two analyses of existing data under way Research needs: Cardiovascular cause-of-death misclassification on death certificates Peru EMF Epi LIK 03_01.17 Neurodegenerative Diseases Increasingly geriatric population Suggested risks associated with occupational electrical factors (e.g., jobs, shocks) No prior studies specifically designed to examine EMF Little ongoing work Research needs: Strong methodologic studies looking at electric shocks and other EMF exposures Peru EMF Epi LIK 03_01.18
Reproductive Overall negative epidemiologic and laboratory work Two recent analyses point to exposures not previously looked at Research needs: Will depend on results yet to be published Peru EMF Epi LIK 03_01.19 Types of Epidemiologic Studies of Exposure Populations near antennas and base stations (including cluster studies) Occupational/Military personnel studies Cell phone users Richard Tell Associates, Inc. Las Vegas, NV Peru EMF Epi LIK 03_01.20
Critical Exposure Parameters in Cell Phone Studies Number of calls and call duration Power level of cell phone Left- or right-hand use User positioning of phone at the face Phone type / model Peru EMF Epi LIK 03_01.21 Limitations Ecologic fallacy Small numbers Previously identified clusters Potential confounding Exposure assessment, Exposure assessment, Exposure assessment Peru EMF Epi LIK 03_01.22
Occupational Studies of Exposure Few cohort and case-control studies Outcomes of interest: leukemia and brain cancer (other outcomes include uveal, testicular, breast and lung cancer) Inconsistent, unreplicated results for various cancer types Richard Tell Associates, Inc. Las Vegas, NV Peru EMF Epi LIK 03_01.23 Limitations Job title classification Lack of measurements Lack of control for potential risk factors Some used external comparisons Peru EMF Epi LIK 03_01.24
Critical Exposure Parameters in Cell Phone Studies Number of calls and call duration Power level of cell phone Left- or right-hand use User positioning of phone at the face Phone type / model Peru EMF Epi LIK 03_01.25 Cell Phone Studies Three case-control and two cohort studies of cell phone users Focus on brain cancer Results negative Hints of location of tumor and handedness Peru EMF Epi LIK 03_01.26
Limitations Crude assessment No measurements Low usage Short latency Hospital controls Peru EMF Epi LIK 03_01.27 - Epidemiology Comparative Analysis Similar: High public awareness Focus on involuntary exposure from power- lines and antennas Potentially large public health impact Difficulties in exposure assessment exacerbated by unknown biophysical mechanism Peru EMF Epi LIK 03_01.28
Differences Studies Much more sophisticated exposure assessment More plentiful Addressing broader range of outcomes Somewhat more consistent Studies Severely limited by exposure assessment which is likely to be even more difficult than for Evolving technology Limited by latency Only a few outcomes examined (mostly cancer) Limited methodologically Peru EMF Epi LIK 03_01.29 Complexities of EMF Science Epidemiology Large misclassification Small risk Lack of consistency Animal studies Relevant exposure Right model Power to detect small risk In Vitro Lack of robust effect Replication Relevance Integration Multidisciplinary approach needed Carcinogenesis is a complex and highly variable process Peru EMF Epi LIK 03_01.30