Unknown authors · 1998
Researchers exposed 256 male rats to 50 Hz magnetic fields at 5 microTesla for 22 hours daily over 32 weeks, covering about 70% of their lifespan. The study found no significant differences in blood chemistry, organ structure, or brain neurotransmitters between exposed and control animals. This suggests that prolonged exposure to power-line frequency magnetic fields at this intensity may not cause detectable biological changes in rats.
Malyapa RS et al. · 1998
Researchers exposed rats to 2450 MHz microwave radiation (the same frequency used in microwave ovens and some WiFi devices) for 2 hours to see if it would damage DNA in brain cells, as a previous study had suggested. They found no DNA damage in either the brain's cortex or hippocampus regions, contradicting the earlier research. This study suggests that short-term exposure to this type of radiation at moderate levels may not cause immediate genetic damage to brain cells.
Unknown authors · 1998
This 1998 study examined how 60 Hz magnetic fields from power lines affect melatonin production in electric utility workers. Researchers found that workers exposed to temporally stable magnetic fields - those that remain relatively constant over time - had reduced levels of a melatonin metabolite in their urine. This suggests that steady magnetic field exposure may disrupt the body's natural sleep hormone production.
Unknown authors · 1998
Researchers measured magnetic field exposure and melatonin levels in electric utility workers over three consecutive days. They found that temporally stable 60 Hz magnetic fields (the kind from power lines) were associated with reduced nighttime melatonin production. This matters because melatonin is crucial for sleep, immune function, and protecting against cancer.
Unknown authors · 1998
Danish researchers tracked over 21,000 utility workers for nearly 20 years and found they had twice the normal rate of death from ALS (Lou Gehrig's disease). The increased risk appeared linked to higher electromagnetic field exposure levels and repeated electrical shocks on the job.
Daniells et al. · 1998
Scientists exposed genetically modified nematode worms to microwave radiation at 750 and 300 MHz frequencies and measured their cellular stress responses through a special gene that acts like a biological alarm system. The worms showed significant stress responses to the microwave exposure, with the strongest effects occurring closest to the radiation source and weaker responses at lower power levels. This suggests the radiation was causing cellular damage similar to what toxic metals produce, rather than simple heating effects.
Unknown authors · 1998
Researchers exposed rats to 60 Hz magnetic fields (the same frequency as power lines) for one hour before water maze training sessions. While the rats could still learn to find a hidden platform, they swam slower and showed impaired spatial memory when tested later. This suggests power line frequency magnetic fields may affect brain function and memory formation.
Unknown authors · 1998
Researchers exposed rats to 60 Hz magnetic fields (the same frequency as household power lines) for one hour before maze training sessions. While the rats could still learn to find a hidden platform, they swam slower and showed impaired spatial memory when tested later. This suggests power frequency magnetic fields may affect brain function and memory formation.
Unknown authors · 1998
University of Washington researchers exposed rats to 1 mT, 60 Hz magnetic fields (power line frequency) for one hour before each water maze training session. While the rats learned to find the platform normally, they swam slower and showed impaired spatial memory during testing, suggesting the magnetic field changed how their brains processed location information.
de Seze R, Fabbro-Peray P, Miro L · 1998
French researchers exposed 20 healthy men to cell phone radiation for 2 hours daily over one month and measured six key hormones produced by the pituitary gland. They found no lasting changes in hormone levels, with only a temporary 21% decrease in thyroid-stimulating hormone that returned to normal after exposure ended. This suggests that typical cell phone use doesn't cause permanent disruption to the body's hormone control center.
Fetter JG, Ivans V, Benditt DG, Collins J, · 1998
Researchers tested whether digital cell phones interfere with implantable cardioverter-defibrillators (ICDs), life-saving devices that shock the heart back into normal rhythm when dangerous arrhythmias occur. Testing 41 patients with ICDs and various phone models, they found no interference with normal ICD function during typical phone use. However, placing a phone directly on top of an ICD (within half a centimeter) could temporarily disable the device's ability to detect dangerous heart rhythms.
Szmigielski et al. · 1998
Researchers studied 61 workers exposed to radio frequency electromagnetic fields and found their natural daily blood pressure and heart rate patterns were disrupted - the normal peaks and valleys were flattened and shifted earlier, suggesting EMF exposure interferes with the body's cardiovascular rhythms.
Imaida K et al. · 1998
Japanese researchers exposed rats to 929.2 MHz cell phone radiation for 90 minutes daily over 6 weeks to test whether the radiation could promote liver cancer development. The study used relatively high SAR levels (up to 7.2 W/kg) and found no difference in pre-cancerous liver lesions between exposed and unexposed rats. This suggests that cell phone radiation at these levels does not accelerate liver cancer progression in this animal model.
Imaida et al. · 1998
Researchers exposed rats to 1.439 GHz radiofrequency radiation (the type used in Japanese cell phones) to see if it would promote liver cancer development. Despite using exposure levels up to 1.91 W/kg and finding evidence of biological stress (increased stress hormones), the radiation did not increase cancer-promoting changes in the liver. This suggests that cell phone radiation at these levels does not accelerate liver cancer progression in this animal model.
Bassen HI, Moore HJ, Ruggera PS · 1998
Researchers tested how digital cell phones affect implantable cardioverter-defibrillators (ICDs), medical devices that shock the heart back into rhythm during dangerous arrhythmias. They found that phones using TDMA technology could cause ICDs to malfunction when held within 2-6 centimeters of the device, either preventing necessary pacing or triggering inappropriate high-voltage shocks. The interference stopped immediately when phones were moved away from the ICD.
Frei et al. · 1998
Researchers exposed 100 mice genetically prone to breast cancer to microwave radiation at 2450 MHz (the same frequency used in microwave ovens and early WiFi) for 78 weeks, 20 hours per day. They found no difference in cancer rates between exposed mice (38%) and unexposed mice (30%), and no difference in how quickly tumors developed or grew. This suggests that chronic exposure to this specific level of microwave radiation did not increase breast cancer risk in these cancer-prone animals.
Unknown authors · 1998
Researchers exposed rat tracheal cells to 50 Hz magnetic fields (100 microTesla) and found they triggered the same cellular stress proteins as ionizing radiation. The magnetic field exposure activated c-jun and c-fos oncoproteins, which are markers of cellular damage and stress response.
Unknown authors · 1998
Researchers exposed human blood cells to 60 Hz magnetic fields (the same frequency as power lines) and found that while the fields alone didn't activate protein kinase C, they amplified the effects when cells were already stimulated by chemicals. This suggests magnetic fields may enhance biological processes that are already active rather than starting new ones.
Unknown authors · 1998
Researchers exposed human blood cells to 60 Hz magnetic fields (the same frequency as power lines) and found the fields enhanced the activity of protein kinase C, a key enzyme involved in cell signaling. The magnetic fields didn't create new biological effects but amplified existing cellular processes that were already activated.
Unknown authors · 1998
Researchers at the FDA exposed HL60 cancer cells to 60 Hz magnetic fields at 6 microTesla (similar to power line levels) to test whether this EMF exposure increases MYC gene expression. Despite using methods identical to earlier studies that claimed positive effects, they found no increase in MYC expression. This failed replication raises questions about the reproducibility of some EMF biological effects.
Walters TJ et al. · 1998
Scientists exposed rats to 2.06 GHz microwave radiation and measured brain temperatures. High-power microwaves created uneven heating patterns, with some brain areas heating 2-2.5 times faster than nearby regions. This uneven heating didn't occur with conventional heat sources like warm water.
Unknown authors · 1998
Researchers attempted to replicate earlier claims that 60 Hz magnetic fields (the frequency of power lines) activate immune cell signaling in laboratory B cells. Using rigorous blinded testing methods, they found no evidence that 1-gauss power line frequency fields affect these cellular processes. This study challenges previous research suggesting power line EMF can trigger biological responses in immune cells.
Unknown authors · 1998
Researchers exposed human leukemia cells to 60 Hz magnetic fields (the same frequency as power lines) for up to 2 hours to test whether this EMF could activate cancer-promoting genes. They found no changes in oncogene activity, contradicting earlier claims that power line frequencies could trigger cancer gene expression.
Unknown authors · 1998
Researchers tested whether 60-Hz magnetic fields at 0.1 mT could trigger cancer-related gene activity in human immune cells, attempting to replicate previous findings. They found no changes in oncogene transcription rates or levels after exposures ranging from 15 minutes to 2 hours. This study failed to reproduce earlier claims that power-line frequency magnetic fields activate cancer genes.
Mickley GA, Cobb BL · 1998
Researchers exposed rats to microwave radiation at levels that caused significant body heating and found it disrupted their ability to distinguish between familiar and new objects - a key indicator of working memory function. However, rats that had been previously exposed to the heating developed a tolerance that protected them from both the temperature increase and memory problems. The study suggests that microwave-induced heating can impair cognitive function, but the brain may adapt to protect itself from repeated exposures.
