Get access to over 1,300 articles and reader Q&As
When I was a kid, we had an alarm in the house with a motion sensor. It was mounted on the wall in the hallway and covered with a wooden box. This, my friends, was the “Zapper Stopper.” Its goal, as I recall, was to stop whatever dangerous radiation was coming out of the motion sensor. I never really questioned the validity of this explanation, but I think of it frequently when people write to me expressing their concerns about electromagnetic fields (EMFs).
“Is it dangerous to use a microwave near the baby?”
“Should I not buy a house near power lines?”
“Will cell phones give me cancer?”
EMFs are areas of energy (radiation) created by electrical charges. They are everywhere — they emit from power lines, household appliances, and the sun. Cell phones emit radio-frequency EMFs. Along with their ubiquity is a concern about health impacts. In recent weeks, RFK Jr. has been vocal about his concerns about EMFs, including 5G, and cell phones. The FDA removed some pages from its website that had included reassuring data on cell phones and cancer.
The specifics of these concerns are often nebulous, but in the medical literature, the primary concerns that are studied are about cancer, especially childhood leukemia and brain cancer. Conceptually, there are two questions here, associated with two different types of exposure.
First: cell phones. Do they cause cancer?
Second: Is there evidence of risks from exposure to power lines, in-home appliances, or heating sources — all of which produce low-frequency electromagnetic fields or magnetic fields?
We’ll take these in turn.
Do cell phones cause cancer?
The longest-standing concern with cell phones is the possible link with brain cancer.
Back in 2008, a review of case-control studies argued for a significant link between cell phone use and several kinds of brain tumors. However, as better data has emerged, this link has not persisted.
One piece of better data is a 2024 study with a prospective cohort design. This large study recruited people, asked them about their mobile phone use, and followed them over time, looking for tumor development. This is better than the case-control approach, which finds people with brain tumors and asks them about their use in the past. In the better data, there is no link between phone use and brain tumors.
The second way we can evaluate this is by simply looking at time trends. Below is a graph of cell phone subscriptions and brain cancer, from 2000 through 2022.
Cell phone usage has exploded over time; brain cancer rates have, if anything, declined. Time trends are always hard to learn anything conclusive from, but if cell phones were an important cause of brain tumors, it seems likely that we would have seen these increase over time.
What about other kinds of cancer?
There are studies that suggest such a link, but the evidence is not compelling. Here is one large study example, which follows people over time and looks at cancer development as a function of the amount of mobile phone usage. This study argues that prostate cancer and non-melanoma skin cancer may be increasing as a result of cell phone use.
Neither of these makes a lot of sense. It’s hard to see what the mechanism would be for cell phone radiation to cause skin cancer or prostate cancer. Prostate cancer, in particular, has declined over time, which is, again, inconsistent with the rise in phone usage. A much more likely explanation for the findings in this paper is a combination of bias (cell phone users are different in other ways than nonusers) and p-hacking (if you look at enough outcomes, you’re likely to find significant differences where there are none).
Newer cell networks use 5G and, again, that has led to new concerns. But there is no evidence that 5G causes cancer either, and the time trend arguments above also apply. As 5G has increased over the past several years, brain cancer rates have (for example) declined.
The bottom line is that there is little to no evidence, mechanistic, epidemiological, or otherwise, that cell phones cause cancer.
What about other forms of exposure?
It is also important to say here that when concerns are raised about exposure, they are nearly always about exposure at high levels, to power lines or other environmental factors. The kind of exposure that comes out of household appliances (e.g., all your questions on Wi-Fi routers and white-noise machines) is much, much more minimal.
So, what about power lines? This is a more complicated question since some scientific organizations have raised this concern.
The International Agency for Research on Cancer (IARC) is one organization tasked with evaluating what exposures — environmental or otherwise — contribute to cancer risk. The IARC has classified low-frequency electromagnetic fields from things like power lines as “possibly carcinogenic to humans” (its classification is “Group 2B evidence”). On one hand, this sounds scary. However, these classifications are generally very conservative, and this evidence level is lower than (for example) the IARC’s assessment of the risk of red meat (Group 2A) or processed meat (Group 1).
Diving into the data, we start to see why this assessment is equivocal. Put simply, the data is a bit confusing.
Broadly, studies in this space focus on analyzing the relationship between some measure of EMF exposure and a cancer outcome. Within the exposure measure, we see studies of both occupational exposure (people who work in jobs with a lot of EMF exposure) and more casual exposure (generally, living near EMF sources). In both cases, the results are conflicting.
To be more concrete, we can start with this 1997 study in the New England Journal of Medicine that focused on the question of power-line exposure and childhood leukemia. This is a case-control study — the authors identified 638 children with leukemia and 620 control children without the disease and compared their power-line exposure. What’s especially good about this study is that they actually measured the EMF levels in the children’s houses, so we have a numerical measure of the exposure.
The paper does not find a significant relationship between EMF exposure level and childhood cancer. In terms of magnitude, their estimate comparing moderate exposure with low exposure is 1.24 — meaning the higher-exposure group had a 24% higher rate — but from a statistical precision standpoint, they cannot rule out that this group had a 14% lower rate or a 79% higher rate. In other words, the estimates are somewhat imprecise.
For the most part, other individual studies come to the same conclusion that there is no significant relationship, but they also all tend to be imprecise (e.g., this one in Canada). Often, in cases where we have many small studies, a meta-analysis approach can be effective at increasing precision. In 2021, a study came out that combined 30 smaller studies, for a total of almost 200,000 participants.
Even with a much larger sample, this meta-analysis still finds mixed and somewhat imprecise results. For example, the authors see a small but significant increase in leukemia risk with exposure but no significant evidence on overall cancers. The risk they observe for leukemia is exactly the same magnitude as in that 1997 study discussed above — about a 25% increase; the only difference is that with the larger sample, they can reject an effect of zero.
But! These effects are still very small in magnitude — a 25% increase may seem big, but the yearly risk of childhood leukemia is about 5 in 100,000, so in absolute terms the increase is limited. Moreover, the studies that make up this meta-analysis are subject to many of the issues I often talk about — notably, the possibility of other differences across groups that relate to the outcome.
This pattern of small, inconsistent results moves across other settings. A study of occupational exposure to high levels of EMF in Switzerland shows no difference in overall cancer rates for groups with higher exposure, but maybe a hint of an increase in two kinds of cancer when exposure is very high. Again, though, the effects are statistically imprecise and subject to the concern that there might be other differences across the groups.
I could go on (a large study of children in Finland, for example), but the patterns in what we see in the data are consistent. With such a rare outcome, it’s hard to be precise about any conclusions, and in most cases, we see largely reassuring results and occasionally a hint of a small relationship.
At best, this epidemiological evidence is inconclusive. It’s also complicated by the fact that there is no mechanistic reason to think EMF exposure would lead to cancer, no animal model that would suggest a link. In some cases — like, say, aspartame — we can point to evidence showing that if mice are fed a diet made up entirely of this substance, they are more likely to have tumors. That doesn’t prove a link in humans consuming far lower doses (and indeed, in that case such a link is pretty tenuous), but it at least generates a biological plausibility argument. Here, we do not have that. While that doesn’t rule out a link, it is another missing piece.
The question I typically get about this is along the lines of “Should I change where I live as a result of power lines?” Looking at the evidence, I would say no. The evidence base here for any link at all is weak, and even at the top end, any effects identified are extremely small.
The bottom line
- There is no reason to think your cell phone gives you or your child cancer.
- Research finds only a weak connection between low-frequency electromagnetic fields (such as power lines) and cancer, and shows minimal risk at most.
Log in
On the microwave question, on the advice of my radiologist spouse, we stand back a bit from it when it’s in use (as fun as it is to watch popcorn popping in it). Easy to do, no reason not to.
The one thing I think you could have mentioned in an article on this topic is the danger of airport body scanners. I think you’re right there’s no particular reason to worry about cell phones, but there is good reason to avoid body scanners whenever possible. It’s hard to avoid proximity to power lines, but it’s feasible, if annoying, to do alternative screenings at TSA.
We recently bought an induction stove. Should I be worried about exposure from it?