• Typical mobile phone use (calls, browsing, apps using mobile data) contributes the most to RF EMF exposure.

• Wi-Fi and Bluetooth are part of the same electromagnetic spectrum but usually operate at lower intensities.

• The concerns raised in the study are more closely tied to mobile network emissions, especially in scenarios involving prolonged or close-range exposure (like sleeping next to a phone or carrying it in a pocket).

A new international study suggests that exposure to mobile phone radiation (RF EMF) could increase the risk of certain cancers in lab animals. The frequencies examined are the same as those used in wireless technologies such as WCDMA, TDMA, CDMA, and 3G and 4G GSM. Published in Environment International in April 2025, the research—partly funded by the World Health Organization—analyzed 52 experimental studies conducted on rats and mice between 1978 and 2020. It offers a long-term assessment of the potential health effects of electromagnetic radiation, a rising concern as 5G and other wireless technologies continue to expand, introducing new frequency bands.

In Africa, 5G networks are already live in around 15 countries. Technically, the technology can reuse so-called legacy or low-frequency bands (700 to 2600 MHz) from earlier generations, in addition to the dedicated 3.5 GHz band (3.4–3.8 GHz) and higher-frequency millimeter-wave bands (around 26 GHz). Even higher frequencies are under review. 5G relies on an antenna system known as Massive MIMO (Multiple Input, Multiple Output), which uses a dense array of small antennas to focus signals into narrow beams, targeting users precisely. In Nigeria, public backlash following the 2020 rollout led the Senate to commission a health inquiry, which concluded the technology was safe.

Rare but Noteworthy Tumors

The study highlights two cancers with “high” levels of evidence in animals exposed to RF EMF: malignant schwannomas—rare tumors of the peripheral nerves and gliomas, a type of brain tumor. These findings stem primarily from two landmark studies.

The first, by the U.S. National Toxicology Program (NTP), exposed Sprague Dawley rats to 900 MHz waves—used in 2G and 3G networks—at levels far above current standards (6 watts per kilogram versus the European limit of 0.08 W/kg). After two years of daily exposure, 6% of male rats developed heart schwannomas, while none appeared in the control group.

The second, by the Ramazzini Institute in Italy, found similar results at far lower doses—just 0.1 W/kg, close to current safety limits. The appearance of rare tumors in two species, under different conditions, has prompted calls for further investigation. The study also notes a moderate rise in lymphomas (cancers of the immune system) in some mice, along with tumors in the adrenal glands and liver. No increased risk was observed for digestive, kidney, or breast cancers. The authors stress that these results are still preliminary and require more confirmation.

Unclear Mechanisms

Although a statistical link has been shown in animals, the biological mechanisms remain unclear. Telecom waves are non-ionizing and theoretically lack the energy to damage DNA directly. The leading hypothesis is oxidative stress: electromagnetic fields may disturb cellular balance and generate free radicals, which can trigger mutations. Several studies have observed oxidative stress markers, even at low exposure levels.

Another possibility is a subtle thermal effect. Current safety standards, set in the 1990s, are based on the heat threshold (4 W/kg) at which tissue damage occurs. Yet the NTP study found tumors at just 1.5 W/kg—without a detectable rise in temperature—suggesting possible non-thermal effects that challenge the basis of existing regulations.

Assessing human risk remains complex, the researchers admit, due to methodological limits: continuous exposure (up to 19 hours per day), occasionally extreme doses, and genetic variability among rodent strains. Moreover, only 20 of the 52 studies analyzed were full chronic bioassays—the gold standard in cancer research. The others, based on genetically modified animals, provide only indirect evidence.

A Public Health Concern

These findings revive the debate over the health impact of daily exposure to wireless technologies—a growing issue as global hyper-connectivity increases. Although the exposure levels in these studies often exceed those faced by everyday users, experts recommend caution, especially for children and pregnant women. Doctors advise limiting unnecessary exposure: avoid sleeping with phones nearby, use hands-free devices, keep phones out of pants pockets, and turn off Wi-Fi at night.

In 2011, the International Agency for Research on Cancer (IARC) had already classified RF EMF as “possibly carcinogenic” to humans, based on suspected links to gliomas and acoustic neuromas—tumors related to schwannomas. Despite a lack of conclusive proof, largely due to limited research, the agency also advised caution.

Insurers have taken the risks seriously. Since 2013, several reinsurers have excluded electromagnetic wave-related claims from liability policies, calling them “unpredictable.”

In light of persistent concerns, researchers are urging further studies—particularly into the cumulative effects of RF exposure and the frequencies used in 5G. Human cell models, they argue, could help evaluate risks without relying on animal testing.