1. Lecture 27 Chapter 2 April 2,2018
Evaluation of the Toxicity and Potential Oncogenicity
of Extremely Low-Frequency Magnetic Fields
in Experimental Animal Model Systems

2. Basic Background
1. You have inconclusive studies from the epidemiology.
2. You back them up with animal studies where you have control of the exposure conditions and you have data from other studies that show the results in these animals provide information on the effects on humans.
3. The objective of these studies was to find if EMF’s cause or promote cancers. (oncogenicity or are toxic).

3. The Chapter Contains Reports on
1. General and organ- specific toxicity of exposure to power frequency EMF using standardized rodent model systems
2. Possible oncogenicity of EMF as a single agent
3. EMF exposure as a cocarcinogen or tumor promoter. Identify possible activity as a tumor initiator, tumor promoter,

4. Reports Continued.
5. Potential oncogenicity of EMF exposure using genetically modified (transgenic or gene knockout) animals
6. Potential biological mechanisms for EMF effects with emphasis on whole animal studies and neoplastic development.

5. General Toxicologic Bioassays of Electromagnetic Fields
1. No generalized human toxicity resulting from EMF exposure have been published of documented case reports in the peer- reviewed literature
2. It is generally agreed that acute, subchronic, or chronic exposure to EMF is not a significant risk factor for systemic or generalized toxicity in humans.
This not quite true at this point.

6. General Toxicologic Bioassays of Electromagnetic Fields Continued
3. Lack of systemic toxicity of EMF exposure in humans that is clearly supported by the results of acute and subchronic bioassays conducted in animal model systems.
4. The exposure studies sited range from micro-Tesla to two milli-Tesla.
5. The occasional statistically significant difference have not lead reproducible patterns in EMF toxicity in any of the bioassays.

7. General Toxicologic Bioassays of Electromagnetic Fields
1. Conclusions is that it can be concluded that the risks of generalized or systemic toxicity resulting from acute, subchronic, or chronic exposure to EMF are very small.
2. I agree but I think there is enough going on to make it worth unscrambling the puzzle.

8. Developmental and Reproductive Toxicity Studies of Electromagnetic Fields
1. These studies started as result of teratogenesis in chick embryos exposed to high-EMF flux densities.
2. The relevance of these studies to humans is questioned.
3. Second a study indicating a small increase in birth defects for use of electric blankets.
This study did not have EMF values or separate out the possible effects of heating.

9. Developmental and Reproductive Toxicity Studies of Electromagnetic Fields
1. Followed by a lot of epidemiological studies that did not find a statistically significant risk of birth defects.
2. This is supported by more than a dozen teratology studies in pregnant rodents which did showed no increase in teratology.
3. One study showed a reduction in fetal survival for rats at 30mT

10. Immunotoxicity Studies of Electromagnetic Fields
1. A lot of rodent studies have been done on the immune system and it seems to be a good model for humans.
2 immune function assays include (lymphoid organ weight, lymphoid organ cellularity, lymphoid organ histology, B- and T-cell-mediated immune responses, natural killer (NK) cell function, lymphocyte subset analysis, host resistance and they were evaluated for exposures of 2mT for 4 weeks to 3 months.

11. Immunotoxicity Studies of Electromagnetic Fields Results
1. Only changes shown was the suppression of NK cell function in two studies for female mice.
2. This did not seem too important in the animals resistance to Infectious disease challenges.

12. Field Exposure Studies
1. These are lifetime studies 18months to 2y
2. These are big expensive studies
3. For one study the experimental groups of 100 animals /group included animals receiving continuous exposure to field strengths of 20 mG (equivalent to 2 μT), 2G (200 μT), or 10G (1 mT), or intermittent exposures (1 h on/1 h off) to 10G (1 mT). At 60Hz.

13. Results
1(1) A statistically significant decrease in the incidence of malignant lymphoma in female mice exposed intermittently to 10G EMF
(2) Significant decreases in the incidence of lung tumors in both sexes of mice exposed to EMF at 20 mG or 2G (but not at 10 G)
(3) A statistically significant decrease in the incidence of trichoepitheliomas of the skin in male rats exposed continuously to 10G EMF

14. Results
(4) A statistically significant decrease in the incidence of adrenal cortical adenomas in female rats exposed intermittently to 10G EMF
(5) A statistically significant increase in incidence of thyroid C-cell tumors in male rats exposed to EMF at field strengths of 20 mG or 2G (but not at 10 G)

15. Conclusions
1. When considered together, the results of these studies provide no evidence that EMF
exposure is a significant risk factor for human cancer. No increases in the incidence of neoplasia in the brain, breast, or hematopoietic system were observed
2. However several studies indicate decreases in tumor incidence.

16. Chronic Oncogenicity Bioassay in Rats
1. Exposures 60 Hz magnetic fields for 20 h/d for 2 y ,50 rats per group
2. EMF exposures were initiated 2 d before animal birth, rather than in young adult animals
3. EMF at field strengths of 20 mG (2 μT), 200mG (20 μT), 2G (200 μT), and 20G (2 mT).
Results were that the incidences of pituitary adenomas in all groups exposed to EMF were decreased from those seen in both the sham control group and the cage control group

17. Chronic Oncogenicity Bioassay in Rats
1. Groups of 48 rats per sex were exposed for >21 h/d for 2 y to 50 Hz EMF at field strengths of 5G (500 μT) or 50G (5 mT)
2. For a large number of parameters no change.
3. Increase in the incidence of a benign lesion fibroma
4. A decrease in the total incidence of invasive neoplasms at 5G)

18. Lymphoma and Brain Tumor Bioassay in Mice
1. One group of 380 female C57BL/6 mice was exposed to circularly polarized 60 Hz EMF at 14.2G(1.42 m T) for up to 852 d.
2. No statistically significant effects on animal survival or on the incidence or latency of hematopoietic malignancy

19. Lymphoma Bioassay in Mice
1. High flux densities (250G [25 mT] of 60 Hz EMF
2. Suggested an increased incidence of malignant lymphoma in the second and third generations of exposed animals.
3. This study is strongly criticized for some good reasons.

20. Possible Cocarcinogenic or Tumor-Promoting Activity of Electromagnetic Field
1. Because EMF is apparently not genotoxic, it is logical to conclude that any oncogenic effects of exposure are mediated through cocarcinogenic or tumor promotion mechanisms
2. Most multistage tumorigenesis studies are based on the initiation–promotion paradigm

21. Multistage Oncogenicity Studies in the Brain
1. Two studies showed 60Hz EMF as promoter of brain tumor induction.
2. One at (20 mG [2 μ T], 200 mG [20 μ T], 2G [200 μ T], and 20G [2mT])
3. Second at (14.2G [1.4 mT]) for up to 852 d
Neither study showed any significant activity for by the EMF

22. Multistage Oncogenicity Studies in the Mammary Gland
1. First study suggests promotion MG Tumors by 50Hz EMF
2. Second study 50Hz, 100µT reported increase. Next study at 0.3 to 1.0 mT for 13weeks showed no increase.
3. Follow up study of second study showed a decrease in number of tumors possibly due different strain of rats.
4. Next study no change.

23. Lymphoma Promotion Study in Mice
1. Zhejiang Medical University no significant change
2. UCLA +VA study only statistically significant difference from matched sham controls was a reduction in lymphoma risk in mice exposed to EMF after exposure to an ionizing radiation dose of 5.1 Gy.

24. Possible Oncogenic Activity of EMF Using Genetically Modified (Transgenic and Gene Knockout) Rodent Models
1. This approach has some advantages in the ease of being able to get reproducible results and the need for smaller test groups.

25. Results of IITRI (United States) Lymphoma Bioassay in PIM Transgenic Mice
Groups of 30 mice per sex received a single intraperitoneal dose of 25 mg ENU and
were then exposed for 18.5 h/d for 23 weeks to pure, linearly polarized 60 Hz magnetic
fields. Experimental groups included animals receiving continuous exposure to field
strengths of 20 mG (2 μ T), 2G (200 μ T), or 10G (1 mT), or intermittent exposures (1 h
on/1 h off) to 10G (1 mT).

26. Results
For the chronic study the only statistically significant difference from sham control was a significant decrease in the incidence of lymphoma in male mice exposed continuously to EMF (23% incidence versus 49% incidence in sham controls; p = via Fisher’s exact test).

27. Results P53 Knockout Mice
Consistent with the results of the lymphoma bioassay in PIM mice, exposure to 60 Hz EMF at a flux density of 10G had no effect on lymphoma induction in heterozygous p53 knockout mice.
Lymphoma incidence in both sexes in the sham control group was 3% (1/30). By comparison, lymphoma incidence in male mice in the 10G group was 0% (0/30), while female mice exposed to 10G had a 7% incidence of lymphoma (2/30).
Although this study was of limited statistical power, it provides no evidence to support the hypothesis that EMF exposure is a risk factor for lymphoma induction.

28. Walter and Eliza Hall Institute of Medical Research (Australia): Lymphoma Bioassay in PIM Transgenic Mice
in comparison to a lymphoma incidence of 29%in the sham control group, the incidence of lymphoma main groups exposed to EMF ranged from 26% to 35% (p > 0.05 for all comparisons). By contrast, mice exposed to a positive control material (ENU) demonstrated a lymphoma incidence of 60% at 9 months.

29. Proposed Mechanisms of Electromagnetic Field Action in Oncogenesis
. Genetic toxicity (DNA damage, clastogenesis, or mutagenesis)
. Alterations in gene expression
. Biochemical changes associated with regulation of cell proliferation
. Alterations in immune function
. Alterations in melatonin levels or action

30. Genetic Toxicology Studies of Electromagnetic Field Exposure
It is generally agreed by investigators in the field that ELF magnetic fields do not possess sufficient energy to damage DNA via direct interaction (reviewed in [4]).
Although it is possible that power frequency EMF could damage DNA through an indirect mechanism (i.e., via generation of free radicals), the vast majority of well-designed genetic toxicology studies conducted in models with demonstrated predictiveness for DNA-damaging activity have failed to identify any significant mutagenic or clastogenic effects of EMF exposure.

31. A Possible Explanation of Results
1. Do exposures electric magnetic field lead to an Adaptive response.
Adaptive response is a phenomenon in which cells which were pre-exposed to extremely low and nontoxic doses of a genotoxic agent became resistant to the damage induced by subsequent exposure to a higher and toxic dose of the same, similar (in action) or another genotoxic agent.

32. Conclusion
1. There is not support for saying that low levels of 60Hz magnetic fields cause health effects from the animal studies.
2. The biological changes that are seen are hard to reproduce and inconsistent.
3. The mechanisms for going from the physics to the biological effects are not completely understood.

33. Lecture 28, April 4, 2018
Do an analysis for the material in Chapter 2 of the second volume. Or better of the two chapters by David McCormick which are an up dated. These should be on the class web site. I would like you to come up with a hypotheses for the extended life of the male rats in then NTP study and back it up with data from earlier studies and or data from earlier chapters.

34. Report of Partial Findings from the National Toxicology Program Carcinogenesis Studies of Cell Phone Radiofrequency Radiation in Hsd: Sprague Dawley® SD rats (Whole Body Exposures) Draft
1. Exposure of Harlan Sprague Dawley rats exposed to RFR at [Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM)] at two frequencies (900 MHz for rats and 1900 MHz for mice) Rats were exposed to GSM- or CDMA-modulated RFR at 900 MHz with whole-body SAR exposures of 0, 1.5, 3, or 6 W/kg. RFR field strengths were frequently adjusted based on changes in body weight to maintain desired SAR levels.
Exposures

35. NTR
2. This report contains peer-reviewed, neoplastic and hyperplastic 10 findings only in the brain and heart of Hsd:Sprague Dawley® SD® (HSD) rats exposed to RFR 11 starting in utero and continuing throughout their lifetimes. These studies found low incidences of 12 malignant gliomas in the brain and schwannomas in the heart of male rats exposed to RFR of the 13 two types [Code Division Multiple Access (CDMA) and Global System for Mobile 14 Communications (GSM)] currently used in U.S. wireless networks. Potentially preneoplastic 15 lesions were also observed in the brain and heart of male rats exposed to RFR.

36. NTR
Lastly, the tumors in the brain and heart observed at low incidence in male rats exposed to GSM- 2 and CDMA-modulated cell phone RFR in this study are of a type similar to tumors observed in 3 some epidemiology studies of cell phone use. These findings appear to support the International 4 Agency for Research on Cancer (IARC) conclusions regarding the possible carcinogenic 5 potential of RFR.

37. NTR
Rats were exposed to GSM- or CDMA-modulated RFR at 900 MHz with whole-body SAR exposures of 0, 1.5, 3, or 6 W/kg. RFR field strengths were frequently adjusted based on changes in body weight to maintain desired SAR levels.

38. Results
In pregnant rats exposed to 900 MHz GSM- or CDMA-modulated RFR, no exposure-related effects were observed on the percent of dams littering, litter size, or sex distribution of pups. Small, exposure-level-dependent reductions (up to 7%) in body weights compared to controls were observed throughout gestation and lactation in dams exposed to GSM- or CDMA-modulated RFR. In the offspring, litter weights tended to be lower (up to 9%) in GSM and CDMA RFR-exposed groups compared to controls. Early in the lactation phase, body weights of male and female pups were lower in the GSM-modulated (8%) and CDMA-modulated (15%) RFR groups at 6 W/kg compared to controls. These weight differences in the offspring for both GSM and CDMA exposures tended to lessen (6% and 10%, respectively) as lactation progressed.

39. Results
At the end of the 2-year study, survival was lower in the control group of males than in all 2 groups of male rats exposed to GSM-modulated RFR. Survival was also slightly lower in control 3 females than in females exposed to 1.5 or 6 W/kg GSM-modulated RFR. In rats exposed to 4 CDMA-modulated RFR, survival was higher in all groups of exposed males and in the 6 W/kg 5 females compared to controls.

40. Results

41. Results

42. Results

43. Results

44. Results

45. Results

46. Discussion
The historical control rate of schwannomas of the heart in male Harlan Sprague Dawley rats is 1.30% (7/539) and ranges from 0-6% for individual NTP studies (Table D2, Appendix D). The % observed in the 6 W/kg GSM- and CDMA-modulated RFR groups exceeds the historical incidence, and approaches or exceeds the highest rate observed in a single study (6%). The increase in the incidence of schwannomas in the heart of male rats in this study is likely the result of whole-body exposures to GSM- or CDMA-modulated RFR.

47. Discussion
Currently in males, the historical control rate of malignant glioma for those studies is 2.0% (11/550) and ranges from 0-8% for individual studies (Table D1, Appendix D). The % observed in all of the GSM-modulation groups and in the 6 W/kg CDMA-modulated group only slightly exceeds the mean historical control rate and falls within the observed range.

48. Discussion
The survival of the control group of male rats in the current study (28%) was relatively low compared to other recent NTP studies in Hsd:Sprague Dawley® SD® (Harlan) rats (average 47%, range 24-72%). If malignant gliomas or schwannomas are late-developing tumors, the absence of these lesions in control males in the current study could conceivably be related to the shorter longevity of control rats in this study.

49. Conclusions
Under the conditions of these 2-year studies, the hyperplastic lesions and glial cell neoplasms of the heart and brain observed in male rats are considered likely the result of whole-body exposures to GSM- or CDMA-modulated RFR. There is higher confidence in the association between RFR exposure and the neoplastic lesions in the heart than in the brain. No biologically significant effects were observed in the brain or heart of female rats regardless of modulation.

50. Kheifets, Leeka; UCLA School of Public Health, Epidemiology;
Cell Phone Use and Behavioral Problems in Children: An Analysis Based on Prospective Cohort
Sudan, Madhuri; University of California, Los Angeles, Department of Epidemiology
Olsen, Jørn; University of Aarhus, Institute of Public Health, Department of Epidemiology
Arah, Onyebuchi; UCLA Fielding School of Public Health, Department of Epidemiology
Obel, Carsten; University of Aarhus, Institute of Public Health, Department of Epidemiology
Kheifets, Leeka; UCLA School of Public Health, Epidemiology;

51. Results What’s Known on This Subject:
Children are increasingly exposed to cell phones beginning at very early ages, including in utero. Many parents and pediatricians are concerned that this technology could have negative health effects, but studies of children’s exposure are few.
What This Study Adds:
This is the first large scale cohort study to prospectively examine cell phone use (during pregnancy and at age 7) and behavioral problems (at age 11). Our findings support the link between cell phone use and behavioral problems in children.