Carriers began rolling out 5G, or fifth-generation, smartphones to select cities in 2018 and have since expanded into other areas. More comprehensive rollouts are expected in 2020, which will likely popularize the high-speed cellular technology.

So, why all the buzz?

Users have frequently complained about delays in 4G speeds during busy times of the day in heavily populated regions. Cellphone carriers say the introduction of 5G will mitigate this issue because of its instantaneous speeds.

In fact, the speeds are said to be 100-times faster than what we’re using today. But the move toward 5G has revived concerns about whether or not long-term exposure to cellphone radiation causes cancer.

Many publications including The New York Times and Independent, the Federal Communications Commission and major cellphone companies have refuted these claims, but the truth is a bit more complicated.

“A classic definition of safety is as follows: a thing is safe if its risks judged to be acceptable,” said Jonathan Samet, dean of the Colorado School of Public Health, told MedTruh in July. “I think it's useful because it separates out knowing what the risks are from judging whether they're acceptable. Right now, I don't think we have anywhere near certain enough understanding of what the risks are.”

There are two categories of radiation on the electromagnetic spectrum: non-ionizing radiation and ionizing radiation. According to the National Institute of Environmental Health Sciences, non-ionizing radiation, which is connected with everything from computers to microwave ovens, is typically seen as harmless.

On the other hand, ionizing radiation, such as that from ultraviolet radiation or x-rays machines, can “under certain circumstances, lead to cellular and or DNA damage with prolonged exposure.”

The kind of radiation produced by cellphones, called radiofrequency radiation (RFR), are grouped into the non-ionizing category, meaning it doesn’t emit enough energy to damage DNA, said Samet, who has previously investigated the occurrence and causes of cancer.

The new 5G signal will be transmitted on a higher wavelength called the millimeter wave, which is the same radio wave utilized by full-body scanners at airports.

While the millimeter wave is faster than previous generations of cellphone signals, it is also weaker when traveling long distances, Vox reported. To maintain the signal strength users are accustomed to, U.S. wireless companies will need to install around 300,000 new antennas — roughly equal to the total number of cell towers built over the past three decades — CBS News reported.

And, as Vox noted last year, adding more towers means consumers will be exposed to more radiation than ever before.

On top of that, we also have limited research on the impact cellphone radiation can have on the human body.

Though the U.S. Food and Drug Administration (FDA) and the Federal Communications Commission (FCC) say there’s nothing to be worried about, the World Health Organization (WHO) classified RFR as “possibly carcinogenic” in 2011. Other agents in this “possibly carcinogenic” grouping include aloe vera, engine exhaust and pickled vegetables.

“It means we can't say that there's no risk — that is it’s safe,” said Samet, who served as chair of the International Agency for Research on Cancer, the WHO’s specialized cancer agency, when it made the classification.

Even with the research we have, the results can be mixed.

In 2018, the National Toxicology Program, an interagency program of the U.S. Department of Health & Human Services, released the results of a Congressionally-mandated study that analyzed the effects of 2G and 3G cellphone radiation on rats and mice.

Scientists, who conducted the experiment over a period of 10 years, found “clear evidence” of tumors in the hearts of male rats and “some evidence” of tumors in the brains and adrenal glands of male rats. It was unclear if tumors were found in female rats or mice of either gender.

A study from the Ramazzini Institute in Italy produced similar results.

It is worth noting that the NTP reported the exposed male rats experienced “longer lifespans.” The levels of radiation the rodents were exposed to were higher than what people are through regular cellphone use and, unlike humans, the animals were exposed to radiation all over their bodies.

“Our studies were conducted with whole-body exposures to evaluate the potential hazard to exposure across the entire body and not just particular regions,” Dr. Michael Wyde of the NTP told MedTruth in an email. “This allowed us to identify particular organs that may be more at risk to the potential effects of RFR, as was the case in the heart of male rats.”

The NTP has also stressed these findings should not be extrapolated to human cellphone usage.

“Extrapolation of our findings to humans is not straightforward, and our studies were not designed with that as a primary purpose,” Wyde wrote.

“When extrapolating from animal studies to human risk assessment for the effects of RFR, there are many complicating factors that make the evaluation of exposure more complex,” Wyde wrote.

These factors include the different ways people use their cellphones, such as utilizing Bluetooth technology, a speaker or putting the device directly up to their head, as well as the variation in exposure, which is based on the strength of the service signal, he added.

What this all amounts to is that more research is needed to truly know how cellphones affect us, said Samet.

The NTP is collaborating with the National Institute of Standards and Technology (NIST) for more short-term exposure studies that “will focus on further clarifying what we learned in the long-term studies and investigating the possibility of DNA damage in exposed tissues,” Wyde wrote.

It would also like to develop “biomarkers of damage from exposure,” what Wyde described as “measurable physical changes that can be seen in shorter periods of time than what it takes to develop cancer.”

“If we can better understand the mechanisms in animals, we know more about what to look for in humans,” Wyde wrote.

Scientists are also currently awaiting the results of another study that is looking at the exposure of RFR on children and adolescents, said Samet, but he does not know of many other studies currently being conducted.

And while the NTP and the NIST are conducting studies, Samet said a scientific agenda to explore this area more deeply has still not been set. Funding for these types of projects is not always readily available, he added.

 “I wish we were moving on a track to be able to address these concerns,” said Samet. “Dare I say, we are not, and I think it’s really important that we should.”