A study recently reported that the magnets in an iPhone 12 deactivated a Medtronic implantable cardioverter defibrillator. That’s possible because implanted medical devices like defibrillators and pacemakers have magnet-activated switches. Apple acknowledges this risk but says:

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.

Apple has now provided more specific guidance, saying:

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.

Apart from its extra magnets, there’s nothing special about the iPhone 12 here. Other case reports have shown adverse interactions between implanted medical devices and a JUUL e-cigarette and Apple Watch and Fitbit wristbands. More generally, an article in Medical Xpress recommends that implanted medical devices move to a different configuration technology.

For now, the takeaway is for those with an implanted medical device to avoid storing consumer electronics in a breast pocket and avoid wearing sleep tracking devices whose wristbands contain magnets.