Lack of definitive proof that a technology is harmful does not mean the technology is safe, yet the wireless industry has succeeded in selling this logical fallacy to the world. In truth, the safety of wireless technology has been an unsettled question since the industry’s earliest days. The upshot is that, over the past 30 years, billions of people around the world have been subjected to a massive public-health experiment: Use a cell phone today, find out later if it causes cancer or genetic damage. Meanwhile, the wireless industry has obstructed a full and fair understanding of the current science, aided by government agencies that have prioritized commercial interests over human health and news organizations that have failed to inform the public about what the scientific community really thinks. In other words, this public-health experiment has been conducted without the informed consent of its subjects, even as the industry keeps its thumb on the scale.27
This paper presents the results of a replication study performed to investigate earlier Soviet studies conducted between 1974 and 1991 that showed immunological and reproductive effects of long-term low-level exposure of rats to radiofrequency electromagnetic fields (continuous wave 2450 MHz for 7h/day, 5days/week for 30 days). The RF exposure resulted in minor increases in formation of antibodies in brain tissue extract and the exposure did not appear to be pathological. In addition, a study was conducted to replicate a previous Soviet study on effects from the injection of blood serum from RF-exposed rats on pregnancy and foetal and offspring development of rats, using a similar animal model and protocol. Our results showed the same general trends as the earlier study, suggesting possible adverse effects of the blood serum from exposed rats on pregnancy and foetal development of intact rats, however, application of these results in developing exposure standards is limited.
Long-term exposure to Radio Frequency waves or microwave radiation has long been studied and shown to produce all sorts of adverse health effects. See my post on EMF Radiation Exposure Symptoms for a full list of common symptoms. Even the American Cancer Society, who in large part will not fully say that EMF radiation causes long-term harm, and instead errs on the side of not enough research, admits on their website, that:
According to American Academy of Pediatrics President Dr. Robert Block, when cell phones are used by children, "the average RF energy deposition is two times higher in the brain and 10 times higher in the bone marrow of the skull," than for adults.  A July 2008 peer-reviewed study shows that children under the age of eight absorb twice the amount of radiation into their brain tissue as adults due to their lower skull thickness. 
According to a peer-reviewed Dec. 2006 study of 420,095 cell phone users in Denmark, the results showed a "reduced brain tumor risk" among long-term subscribers.  Two other peer-reviewed studies also found that cell phone users had a slightly decreased risk of developing brain tumors. A July 20, 2005 Danish study  found a "decreased risk for high-grade glioma," a malignant brain tumor, and a 2005 Swedish study  also found a "decreased odds ratio" for developing glioma as well as meningioma, another type of brain tumor.
George Carlo seemed like a good bet to fulfill Wheeler’s mission. He was an epidemiologist who also had a law degree, and he’d conducted studies for other controversial industries. After a study funded by Dow Corning, Carlo had declared that breast implants posed only minimal health risks. With chemical-industry funding, he had concluded that low levels of dioxin, the chemical behind the Agent Orange scandal, were not dangerous. In 1995, Carlo began directing the industry-financed Wireless Technology Research project (WTR), whose eventual budget of $28.5 million made it the best-funded investigation of cell-phone safety to date.4
In a separate study by the same Swedish team, they found more than seven times the risk among people using a cell phone more than 20 years and 6.5 times the risk for long-term users of cordless phones. As expected, most of the gliomas and acoustic neuromas were on the same side of the head, which was usually exposed to the phone. In the 2013 official report on the medical evidence for brain tumors, the International Agency for Research on Cancer concluded that radiation from cell phones is “possibly carcinogenic to humans”.