Abstract: The majority of hunters use firearms to hunt wild game, and traditional hunting ammunition contains lead, sometimes exclusively. When a lead projectile passes through an animal, it leaves behind a trail of tiny lead fragments which can extend well beyond the projectile path. These fragments are too small to be sensed while eating, and become a lead exposure pathway: They end up being consumed by humans who eat the meat, and also scavengers that eat the butchered remains that are returned to the landscape. The harmful effects of ingesting lead bullet fragments or lead shot have been reported for more than 100 species of wildlife worldwide. Bullet fragments embedded in game meat have been revealed using medical radiography in previous studies. We have recently applied synchrotron X-ray imaging to ammunition fragmentation for the first time. Our first report [1,2] used the BMIT beamline of the Canadian Light Source, which allowed us to image and resolve tens of thousands of fragments in the sub-10 µm size range where they were not previously known to exist, 20× smaller than what has been revealed with medical radiography. K edge subtraction (KES) imaging was also applied to confirm the elemental composition of the fragments in-situ. We have since extended our studies into the sub-micron size regime using scanning X-ray nanoprobes, and to other types of ammunition and tissues. The results challenge the current understanding of the maximum extent that fragments may be distributed, and the effectiveness of imaging methods used to screen wild game donations at food banks for lead bullet fragments. References:[1] Leontowich, A. F. G., Panahifar, A., Ostrowski, R. (2022) "Fragmentation of hunting bullets observed with synchrotron radiation: Lighting up the source of a lesser-known lead exposure pathway" PLoS ONE, 17(8) e0271987 [2] https://www.cheminst.ca/magazine/article/synchrotron-imaging-reveals-size-and-spread-of-lead-bullet-fragments-in-wild-game/