Spotted by MacRumors, Apple has quietly updated a support document for the iPhone 12 line-up stating that the devices and their MagSafe wireless chargers can cause electromagnetic interference with medical devices such as pacemakers and defibrillators.

“Medical devices such as implanted pacemakers and defibrillators might contain sensors that respond to magnets and radios when in close contact. To avoid any potential interactions with these devices, keep your iPhone and MagSafe accessories a safe distance away from your device (more than 6 inches / 15 cm apart or more than 12 inches / 30 cm apart if wirelessly charging). But consult with your physician and your device manufacturer for specific guidelines.”

Apple also specifically mentions its official MagSafe Charger and MagSafe Duo Charger are accessories which can cause interference. So you should expect this to be true of third party MagSafe chargers and accessories as well.

Apple’s warning follows a report in the Heart Rhythm Journal earlier this month, which claimed iPhone 12 models can "potentially inhibit lifesaving therapy in a patient" due to magnetic interference with implantable medical devices. The report details a test performed by three Michigan doctors where holding an iPhone 12 near a patient's implantable cardioverter defibrillator immediately caused it to enter a "suspended" state for the duration of the test.

"We hereby bring an important public health issue concerning the newer generation iPhone 12 which can potentially inhibit lifesaving therapy in a patient particularly while carrying the phone in upper pockets," the report explains. "Medical device manufacturers and implanting physicians should remain vigilant in making patients aware of this significant interaction of the iPhone 12 and other smart wearables with their cardiac implantable electronic devices."

In its defence, Apple states that “though all iPhone 12 models contain more magnets than prior iPhone models, they're not expected to pose a greater risk of magnetic interference to medical devices than prior iPhone models” but adds the caveat “If you suspect iPhone or any MagSafe accessories are interfering with your medical device, stop using your iPhone or MagSafe accessories.”

In isolation, MagSafe is perhaps the most innovative addition to the iPhone range for several generations but concerns around it are mounting. Notably, in October Apple published another support document admitting MagSafe magnets can damage the magnetic strips and RFID chips in credit cards, security badges, passports and key fobs. It can also damage iPhone cases.

With early leaks for the iPhone 13 revealing significant design changes, hopes will be growing that a revision of MagSafe is among them.