Smart watches and fitness trackers are designed to be worn close to the body, often all day. They sit on the skin, collect health information, and connect wirelessly to phones.
Because of that constant contact, it’s understandable to wonder whether they could affect cancer risk over time.
The question usually comes back to the signals they use to communicate.
What kind of signals these devices use
Wearable devices use low-power radiofrequency signals, most commonly through Bluetooth. These signals are non-ionising. That means they do not damage DNA in the way radiation from X-rays or scans can.
When researchers measure how much of this energy is absorbed by the body, the levels are very low. They sit well below international safety limits that are set to avoid known biological effects. The exposure is also much lower than that from a mobile phone.
In the medical literature, wearable devices are not flagged as a cancer concern. Research focuses on how they can be used safely in healthcare - including in cancer care - without evidence of harm linked to their everyday use.
Why the information can feel unsettling
You may see radiofrequency fields described as “possibly carcinogenic” by international agencies.
This label reflects uncertainty, not proof. It is based on a wide range of exposures, many of them much higher or very different from what consumer wearables produce.
At the levels generated by smart watches and fitness trackers, reviews of the evidence have not identified a credible way these signals would lead to cancer. Regulatory bodies have not issued warnings about cancer risk from wearable devices.
What tends to come up in real life
When clinicians see problems linked to wearables, they are usually local and practical.
Most involve the skin. Irritation, pressure marks, or contact allergy from straps or materials are the common issues, particularly if a device is worn tightly or without breaks.
If a skin change under a device doesn’t settle after removing it for a while, it’s reasonable to show it to a clinician. That’s because ongoing skin changes are worth checking on their own terms, not because cancer is expected.
Based on what we know, smart watches and wearable devices do not appear to increase cancer risk.
Questions like this matter because people pay attention to what they live with every day. Understanding the evidence can replace background worry with context. Earlier understanding isn’t about alarm. It gives people more clarity, more choice, and more ease in asking questions when something doesn’t feel right.
References
Guido K, Kiourti A. Wireless Wearables and Implants: A Dosimetry Review. Bioelectromagnetics, 2020.
Fonseka LN, Woo BK. Consumer Wearables and the Integration of New Objective Measures in Oncology. JMIR mHealth and uHealth, 2021.
Beg S, Handa M, Shukla R, et al. Wearable Smart Devices in Cancer Diagnosis and Remote Clinical Trial Monitoring. Drug Discovery Today, 2022.
Triantafyllidis A, Kondylakis H, Katehakis D, et al. Smartwatch Interventions in Healthcare: A Systematic Review. International Journal of Medical Informatics, 2024.







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