Are Neutrinos Dangerous?

No, neutrinos are not dangerous. Around a hundred trillion of them pass through your body every second — day and night, from the Sun and many other sources — and essentially none of them do anything at all. They are completely harmless, and the very reason for that is the same reason they are so famously hard to detect.

Why are neutrinos harmless?

A particle can only affect your body if it interacts with the atoms in it. The neutrino interacts only through the weak force, which is extraordinarily feeble and short-ranged, so its chance of striking any atom is minuscule. Its cross-section — the effective “target size” for an interaction — is so tiny that a neutrino would typically pass through a light-year of solid lead before interacting once. Against a human body, the odds of any effect are vanishingly small.

How many pass through us?

An enormous number. Roughly 100 trillion solar neutrinos stream through each of us every second. Over an entire human lifetime, only about one neutrino is expected to interact with your body at all — and even that single interaction is utterly inconsequential. This is why the neutrino earned its nickname, the ghost particle.

What about high-energy or supernova neutrinos?

Even the intense neutrino burst from a nearby supernova is harmless at the distances of real stars; you would need to be implausibly close to the explosion for neutrinos to deposit any meaningful energy. For every practical purpose here on Earth, neutrinos are entirely safe — a constant, silent, and completely benign presence.

Read more

• How many neutrinos pass through you?
• What is a cross-section?
• Why is the neutrino called a ghost particle?

References

1. 1.S. Navas et al. (Particle Data Group), Review of Particle Physics (neutrino properties), Phys. Rev. D (2024). DOI: 10.1103/PhysRevD.110.030001.

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