Dark Matter collisions with the Human Body

TL;DR

This study estimates the frequency of WIMP dark matter particles interacting with human body nuclei, finding extremely low interaction rates that are negligible for health but relevant for understanding dark matter properties.

Contribution

It provides the first detailed estimates of WIMP interaction rates with human tissue, considering various WIMP masses and cross-sections, and compares these to experimental data.

Findings

Approximately 10 WIMPs hit a human nucleus annually at 60 GeV WIMP mass.

Up to 10^5 WIMPs may interact annually with a human at 10-20 GeV mass with larger cross-sections.

WIMP interactions pose negligible health risks compared to natural radiation sources.

Abstract

We investigate the interactions of Weakly Interacting Massive Particles (WIMPs) with nuclei in the human body. We are motivated by the fact that WIMPs are excellent candidates for the dark matter in the Universe. Our estimates use a 70 kg human and a variety of WIMP masses and cross-sections. The contributions from individual elements in the body are presented and it is found that the dominant contribution is from scattering off of oxygen (hydrogen) nuclei for the spin-independent (spin-dependent) interactions. For the case of 60 GeV WIMPs, we find that, of the billions of WIMPs passing through a human body per second, roughly ~10 WIMPs hit one of the nuclei in the human body in an average year, if the scattering is at the maximum consistent with current bounds on WIMP interactions. We also study the 10-20 GeV WIMPs with much larger cross-sections that best fit the DAMA, COGENT, and CRESST data sets and find much higher rates: in this case as many as $10^5$ WIMPs hit a nucleus in the human body in an average year, corresponding to almost one a minute. Though WIMP interactions are a source of radiation in the body, the annual exposure is negligible compared to that from other natural sources (including radon and cosmic rays), and the WIMP collisions are harmless to humans.