Click for next page ( 139


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 138
e. Overall Conclusions and Recommendations THE NAVY'S ECo~OG~CAr MONITORING PROGRAM reported no obvious ad- verse ecological effects, such as unusual changes in species populations or large-scale mortality of trees or other organisms, as a result of operation of the ELF communications system during the period of the monitoring program. The monitoring program also did not detect any small effects with well-defined consequences, such as decreases in reproductive fitness, that would be likely to result in major effects in the future. The committee agrees with the general findings of the Navy' ecological monitoring program, within the limitations described in this report, that the researchers' observations provide no evidence of statistically significant, wide- spread, adverse effects of EMFs associated with the ELF antennas. For exam- ple, there is no evidence of short-term impacts of EMFs associated with the ELF antennas on bird populations, although effects within roughly 50-100 m of the antennas would not have been detected. The effect of antenna opera- tion, if any, on leaf-litter decomposition processes and the microbial commu- nity is most likely much smaller than existing natural spatial and temporal variation in the forests. The total operation of the antennas seemed to have no major detrimental effect on upland flora beyond background environmental fluctuations. No experimental data indicated a statistically significant effect of ELF EMFs on the movement of dragon fly larvae, the colonization of leaf 138

OCR for page 138
CONCLUSIONS AND RECOMMENDATIONS 139 litter, or the movement of fish. However, the power of the experimental design and statistics probably could not have detected small effects. Effects of ELF EMFs on soil arthropod populations were small compared with the total variation of the processes measured over the ~ I-year study. No major effects were detected In soil ameba populations. For several studies, either the results were ambiguous and require further evaluation or they were uninforma- tive because of design or analysis problems (see discussion below). ECOLOGICAL EFFECTS The term "small effects" is used in this report to refer to effects whose magnitudes are not likely to exceed those expected from normal perturbations over the short term. A drought is one example of such normal perturbations. The committee recognizes that small effects on populations, mediated through modest changes in response variables, might slowly compound and only later become apparent. Numerous flaws in the ecological studies-as designed, implemented, and interpreted would have compromised detection of many such possible small effects of the antenna operation. As shown in Table 5-l, the individual ecological studies can be sorted into three categories: studies that the committee judged to be acceptable with qualifications (as discussed in Chapters 3 and 4), studies that might be acceptable after more information is obtained or data are reanalyzed, and studies that are unsalvageable because of serious flaws. To some extent, the difficulties are inherent in field and ecological stud- ies in which environmental fluctuations and site-specific differences, even with matched sites, cause changes that are large in relation to potential treatment effects and might obscure them. However, as discussed in Chapters 3 and 4, a number of studies were inadequate for determining small effects because of inappropriate exposure assessment, pseudoreplication, low statistical power, inappropriate interpretations of data, or problems with experiment design. As illustrated by the following specific issues and discussed in the remainder of this chapter, the results of several studies should be re-evaluated so that firmer conclusions can be drawn. The environmental differences between treatment and control sites con- tributed to observed differences and might well have explained more of the variance in biologic responses than the ELF EMFs did. The inconsistency in litter~ecomposition data from year to year illustrates the difficulty. The high

OCR for page 138
~ 40 EVALUATION OF ELF ECOLOGICAL MONITORING PROGRAM TABLE 5-1 Acceptability of Results from Response Variables of Individual Studies of the Ecological Monitoring Programa . . Studies Wetlands: Foliar nutrients Might be Acceptable acce stable with with more informa- qualifications lion or analysis Unsalvageable X Decomposition (moss growthb) X Stomatal resistance X Slime molds X Wisconsin and Michigan birdsC Bird populations X Small vertebrates: Embryo X Fecundity X Homing X Aerobic metabolism X Litter decomposition and microflora: Decomposition X Microflora X Upland flora X Aquatic ecosystems: Algae (chlorophyll-ate) X Insects X Fish X Pollinating insects (increased mortalityb) X Soil arthropods and earthworms: Soil arthropods X Earthworms X Soil amebas X Interpretation of study results should be qualified according to discussions in Chapters 3 and 4. bControlled laboratory experiments are suggested because of evidence of possible effects. Wisconsin bird study and Michigan bird study were combined by the committee for its evaluation.

OCR for page 138
CONCLUSIONS AND RECOMMENDATIONS 141 variability between years in decomposition processes and in the microbial community studies within a site casts doubts on the possible small effects detected. The higher amounts of chiorophyIl-a in algae in a stream at the treatment site were not accompanied by effects observed at higher trophic levels in the stream, as would be expected if there actually were an effect. Controlled laboratory studies might determine whether this effect is real or an artifact of a complex system. ELF-EMF exposure data were analyzed inappropriately in the tree- growth studies. An increase in tree growth due to ELF-EMF exposure was reported and publicized, but the committee's analysis of the primary data indicates misuse of the data. When the analysis is corrected, the growth effect disappears. The distinction between treatment and control sites might have been eliminated for experiments that had short-term response variables because the records of antenna on and off times were not consulted by the investigators. If the antenna was off, for example, during the incubation and embryo period of the developmental substudy of the small-vertebrate study, a treatment site would have become a second control site. . Lack of replication is a problem in many studies and makes conclu- sions site-specific rather than broadly applicable. For example, if the conclu- sion of a study is that the antenna operation had no effect on the treatment site, it cannot be assumed that conclusion can be applied to other sites near the antenna. Most studies would have benefited from an understanding of mecha- nism or the use of mechanistic simulation models which might have improved statistical power, data interpretation, and prediction. The litter decomposition study would have benefitted from the use of a simulation model, although, as discussed in Chapter 3, the results would probably have been the same. A difficulty that runs through the investigations is the lack of statis- tical power in interpreting results and the misuse of statistical methods in eliminating some possible outcomes. The decrease in power from 90% to 70 % and later 30% for some of the small vertebrate studies substantially weakened the researchers' ability to detect possible effects. . . The mortality of bees overwintering at a treatment site was found to be greater than that of bees at the control site, but the investigators argued without sufficient evidence that the observed effects are unlikely to have been caused by the ELF EMFs. Potential substantiation of a small effect was hin

OCR for page 138
1 142 EVALUATION OF ELF ECOLOGICAL MONITORING PROGRAM tiered by provision of an alternative explanation. The data require reanalysis or reconfirmation. Slime mold cultures exposed to ELF EMFs in the field and moved to a laboratory for testing could well have recovered from any small exposure- induced effects in the long period between exposure and examination. The selection of a control site downstream of the treatment site for aquatic-ecosystem studies potentially contaminates the control site with treatment-site ELF-EMF induced effects and casts doubts on the results of the study. IITRI'S ENGINEERING SUPPORT AND PROGRAM MANAGEMENT CHARACTERIZING ELECTRIC AND MAGNETIC FIELDS UTR] did a good job on the engineering aspects of the ecological moni- toring program in characterizing the spatial and temporal characteristics of the electric and magnetic fields. The instrumentation for ELF-EMF measurements appeared to be well designed, well calibrated, and properly used. ITTR} pro- vided ELF-EMF exposure information to the researchers for each study. In addition, IlTRT was responsive to requests from researchers for additional engineering support. PROGRAM MANAGEMENT When UTRI submitted its proposal to the Navy to develop an ecological monitoring program for the ELF antenna sites, it emphasized that its role would be not only management of budgetary components of an agreement, but also oversight of individual studies and ensuring of the quality and credibility of the overall program. This commitment appeared to give assurance that the monitoring program, which would generate extensive data from a wide variety of projects, would be closely supervised and that researchers in the future would be able to look at the results to understand how ecosystems in the upper lake states might respond to external perturbations. In its review of individual study reports, as well as of the overall pro- gram of monitoring for possible effects of the ELF antennas, the committee discovered weaknesses in some aspects of IITRI management of the program.

OCR for page 138
CONCLUSIONS AND RECOMMENDATIONS 143 Chapter 4 of this report discusses weaknesses that were found to be common to many projects. Three of these weaknesses appear to have been caused by lack of adequate oversight. First, ITTR} should have detected problems with use of exposure data through annual researcher reports. In response, ITTR] should have provided more guidance for use of the exposure information and required that an EMF-exposure expert work closely with each study until the study leader understood the types of data available, data variability, and the best methods for applying the data. Also, there should have been greater involvement of an expert in broad-based applied statistics at the earliest phases in the design of this program's studies. Second, responsibility for the lack of archiving and of planning for long-term availability of monitoring-program information appears to rest with IlTRI's management of the program. Third, UTR] should have established a regular internal review process to ensure that each study adequately addressed external criticism. These problems appear to have originated in poor early planning by TTTRI or inadequate followup by TITRI as problems arose during the program. RECOMMENDATION The complexity of assessing the possible ecological impacts of ELF EMFs especially given the diversity of the ecosystems and the variability of their locations and their distances from the antennas, (and therefore the vari- ability of exposures) made it extremely difficult to design and complete ap- propriate and comparable ecological monitoring studies. The following recom- mendation and next steps suggested in the subsequent section reflect the com- mittee's understanding of such difficulties but also indicate the committee's concern for bringing this ecological monitoring program to an appropriate and fruitful conclusion. DO NOT REPEAT THE MONITORING STUDIES Despite the weakness of the monitoring studies, the committee does not recommend that the field studies be repeated because the extensive studies conducted to date have provided no evidence that exposure to ELF EMFs had obvious adverse ecological effects. Although caution must be used in drawing conclusions from the results of most of the studies regarding possible small effects because of faulty study design or analysis, the committee considers it

OCR for page 138
~ 44 EVALUATION OF ELF ECOLOGICAL MONITORING PROGRAM highly unlikely that repetition of the ecological monitoring studies undertaken in this program would produce any new findings about ecological responses to ELF EMFs. If, in the future, the Navy or another entity endeavors to determine effects, especially small effects, of external factors, such as ELF EMFs, a before-and-after, control-and-impact (BACI) approach is recommended and should be a criterion of the RFP. A BACT approach to the monitoring program would have been appropriate if the antennas had not been functional before many of the studies were initiated. Such an approach would require, however, that the monitoring studies differentiate between the effects due to construction of the external agent and operation of the agent. If future monitoring studies of similar external influences on ecosystem components or processes are planned by the Navy or other entity, hypothesis development should consider an approach used in ecotoxicology: The "null hypothesis" is designated a measurable response (i.e., positive finding) of an ecological attribute to an external influence. The research design is then structured to prove this "null hypothesis" wrong, that is, to prove that there is no measurable response. A finding that results in acceptance of a null hypothesis of no measurable re- sponse, as was the case with many of the ELF ecological monitoring studies, does not readily demonstrate that there are no measurable effects, especially small ones. Such a finding could also be due to faulty design or high variation between samples that masked small but real effects of the antenna. SUGGESTED NEXT STEPS REANALYSIS OF THE EXPOSURE-ASSESSMENT DATA The ELF ecological monitoring studies were supplied with ELF-EMF data based on measurements made by IITRI engineering teams. The timing and location of the measurements differed among studies. They included mea- surements made only once a year at some study plots (as in the wetlands study), at the location of each individual of the response species of interest in others (as in the upland-flora study), and as a spatial gradient of exposure levels (as in the bird-nestling study). In addition to those different forms of available ELF-EMF exposure data, the study teams apparently were made aware of the variability in times and outputs of antenna operations. In some studies, the analyses and interpretations of ELF-EMF effects appear to have made use of the exposure data. However, some studies apparently used the

OCR for page 138
CONCLUSIONS AND RECOMMENDATIONS 145 inflation inappropriately, and others might not have fully recognized the importance of the vagaries of antenna operations and output. The committee suggests that the investigators from each ecological moni- toring study reassess their use of data on antenna operation and ELF-EMF data and, if they were used inappropriately, reanalyze the responses of selected ecological variables. In addition, the results of several studies should be reana- lyzed so that firmer conclusions can be drawn. These are the studies labeled in Table 5-! as "Might Be Acceptable With More Information or Analysis." The committee suggests that an organization that is independent of the U.S. Department of Defense or UTR} manage the reanalysis. The reassessment and reanalysis should be performed in close collaboration with biostatisticians familiar with this type of EMF-exposure assessment and engineers knowledge- able about field ELF-EMF exposure measurements. if reanalysis reveals statis- tically significant or suggestive responses of ecological variables to ELF EMFs, these responses could be considered for further controlled study (as discussed below). The committee suggests reanalysis and possible controlled studies so that an opportunity is not lost to improve the understanding of ELF- EMF exposure and possible ecological responses. CONTROLLED LABORATORY STUDIES OF VARIABLES THAT TENDED TO SHOW MEASURABLE EFFECTS The ELF ecological monitoring studies produced few results that tended to show effects of ELF-EMF exposure on selected ecological variables. One effect, the growth response of upland trees, might be an artifact of selective use of exposure data. In other cases, an effect might be a true measurable response, but the experimental design or the complexity of the surrounding ecosystem might have created an environment that made the findings suff~- ciently questionable to warrant further, more-controlled studies. Responses that perhaps could be tested under controlled laboratory condi- tions are the apparent increase In chIorophyIl-a in the aquatic-ecosystem study, the behavioral responses of bees and their overwintering mortality in the pollinating-insects study, and increased moss growth in the litter-decomposi- tion study. The chIorophyIl-a increase appeared to be an increase in cell den- sity rather than in chlorophyll per cell; this possibility could be tested and the ecological Implications analyzed. A similar study might help in understanding whether alterations in bee behavior and mortality are repeatable and can be shown to be caused by ELF-EMF exposure or are artifacts of the less-con

OCR for page 138
~ 46 EVALUATION OF ELF ECOLOGICAL MONITORING PROGRAM trolled, more-complex study sites. The wetland study unexpectedly discovered more moss cover on decomposition bags closer to the antenna treatment sites than in intermediate treatment or background control sites. The increased moss cover caused problems in interpreting data on decomposition, but the variabil- ity in growth of moss should be considered for controlled investigation. The reanalysis of exposure assessments (as discussed above) might uncover addi- tional suggestions of small but measurable responses of ecological attributes to ELF-EMF exposure. if it does, these responses could also receive further study under more-controlled conditions; such studies could be designed also to help to elucidate the mechanisms of response if an EMF effect is observed. Such information might guide researchers in deciding which organisms and response variables are most likely to exhibit effects, if any, of the ELF an- tenna. ANY REANALYSIS OR LABORATORY STUDIES SHOWED BE REVIEWED INDEPENDENTLY Reanalysis of exposure assessments might or might not identify some effects of ELF-EMF exposure on ecological variables not previously observed, and laboratory tests might or might not confirm them. Reanalysis might also strengthen the credibility of the findings of some studies. The committee sug- gests that if reanalyses or laboratory studies are performed, the Navy should arrange for an independent evaluation by a few individuals to assess all of the findings resulting from the reanalysis. The individuals should include biostatis- ticians familiar with ELF-EMF exposure assessment and biologic expertise to determine what the weight of evidence indicates and the biologic or ecological implications of any substantiated treatment effects. A broader integration of all studies should be pursued through the use of quantitative methods designed for such purposes. Integration of related effects, although not statistically signifi- cant, can point to areas where additional study might be warranted. The results of the independent evaluation should be made publicly available. Such an independent final review would serve the Navy and the public in producing more-credible and improved findings of the monitoring program. SUMMARY The committee considers it unlikely that further field-based ecological studies will yield more-substantial conclusions than have been obtained from

OCR for page 138
CONCLUSIONS AND RECOMMENDATIONS 147 the present studies. Possible weak effects (as in chIorophyIl-a, bees, and moss) were identified in the present studies. The committee suggests that some data be reanalyzed to establish whether they can add to confidence in the conclu- sions of the more acceptable studies or identify some other possible effects. Any studies of such possible effects could be pursued under controlled labora- tory conditions and combined with theoretical studies designed to elucidate possible mechanisms. if these strategies are pursued and data reanalysis and laboratory studies are completed, the results of the entire program should be evaluated independently and the results of the evaluation should be made publicly available.