Study: Wi-Fi Earbuds Pose a Thyroid Cancer Risk

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This may be a good time to question the use of Bluetooth headsets. A peer-reviewed study shows radiation from such devices can cause health-threatening thyroid cell damage and cancer.

A study published in Scientific Reports (2024) looked at whether using Bluetooth earbuds or headsets might be linked to thyroid nodules. The study found that people who used Bluetooth devices for longer periods each day had a higher risk of having thyroid nodules, especially those using in-ear earbuds, which sit closest to the thyroid.

What Are Thyroid Nodules?

Thyroid nodules are lumps or growths that form within the thyroid gland (the butterfly-shaped gland in the front of your neck that produces hormones regulating metabolism, heart rate, body temperature, etc.).

Most thyroid nodules are benign (non-cancerous).
They are extremely common:
- Up to 50-60% of adults have at least one nodule if you look hard enough with ultrasound.
- Only about 4-8% of nodules felt by a doctor on physical exam are present; the rest are found incidentally on imaging.

Types of thyroid nodules:

Solid or cystic (fluid-filled)
Single or multiple (multinodular goitre)
Functioning (“hot” – produce thyroid hormone) or non-functioning (“cold”)
Benign causes: colloid nodules, Hashimoto’s thyroiditis, simple cysts, multinodular goitre, etc.
Malignant (cancerous) causes: thyroid cancer (papillary, follicular, medullary, anaplastic, etc.)

Can They Become Malignant?

Thyroid nodules can be malignant from the beginning, but a benign nodule very rarely turns into cancer later.

Key facts about cancer risk:

Overall risk that any given nodule is cancerous: ~5-15% (higher in certain risk groups).
Most thyroid cancers arise de novo (as a new cancerous nodule) rather than a pre-existing benign nodule modifying.
True malignant change of a long-standing benign nodule is exceedingly rare.

Who Is at Higher Risk of a Nodule Being Cancerous?

Higher suspicion if:

Age <30 or >60
Rapid growth of the nodule
History of head/neck radiation (especially childhood)
Family history of thyroid cancer or certain syndromes (MEN2, Cowden, etc.)
Hoarseness, difficulty swallowing, or lymph nodes in the neck
Nodule is hard, fixed, or >4 cm
“Cold” nodule on nuclear medicine scan
Certain ultrasound features (microcalcifications, irregular margins, taller-than-wide shape, increased blood flow)

Even though Bluetooth devices emit non-ionizing radiofrequency (RF) radiation, which is much lower energy than ionizing radiation (like X-rays) and doesn’t break DNA bonds directly, the thyroid is anatomically close to typical headset placement (near-ear, neck region) and is a gland known to be sensitive to electromagnetic exposures.

A literature review on mobile phone RF exposure and thyroid health found altered hormone levels and histopathologic changes in animal models exposed to RF fields. (PMID: 34567874)

This was an observational study, it showed patterns of correlation but does not prove all Bluetooth use causes thyroid problems.

But the facts remain that:

RF radiation can trigger cell-stress responses in thyroid tissue: upregulating heat-shock proteins (HSPs), altering gene expression, affecting calcitonin/C-cell activity.
Reactive oxygen species (ROS) generation in thyroid follicular cells or C-cells, leading to inflammation.
Disruption of the hypothalamic-pituitary-thyroid axis, perhaps via altered receptor signalling or impairment of cellular repair processes.
Cumulative exposure effect, where everyday low-level RF over years gradually affects tissue vulnerability.

What we know from research so far:

Bluetooth and mobile devices give off non-ionizing radiation, which is much weaker than X-rays and cannot directly damage DNA.
However, some animal and laboratory studies suggest that long-term exposure to this type of energy may affect thyroid cells, possibly by increasing cell stress, inflammation, or hormone changes.
Human studies have shown mixed results, so scientists are still working to understand whether everyday device use has meaningful effects on thyroid health.

Practical, low-effort precautions:

Use speakerphone or wired headphones for longer calls.
Limit long hours with in-ear earbuds, since they rest close to the thyroid.
Avoid keeping your phone directly against your body (for example, in a bra strap or shirt pocket).
Keep devices a bit farther away during sleep or when not in use (distance reduces exposure quickly).

These steps are easy, low-cost, and beneficial while scientists continue to study this area. Perhaps we may eventually see health warnings on these devices – perhaps akin to those on cigarettes packs.

As a seasoned science writer reporting over many years this concerned me as I have witnessed an alarming rise in electro-smog in our daily lives (from Wi-Fi exposure, 5G and the constant eye irritation from car LED headlights) and their unquantified and cumulative health impacts.

Personally, I am quitting using my ear buds for now. Hopefully, this study will act as another wake up call to demand more testing. But with the profit motive often put above health, we have good reason to be wary of these new threat vectors in a congested modern urban environment already polluted with so many invisible, unregulated and potentially cancerous radiative impacts.

Author: John O’Sullivan (CEO and co-founder of Principia Scientific International. He is a seasoned science writer, retired teacher and legal analyst)

yogaesoteric
November 27, 2025