Lead micro- and nanoparticles directly observed within gunshot wounds in hunted game meat

Bullets, shot, and other projectiles from firearms can fragment inadvertently when they strike a target. The fragmentation process is concerning for hunting, where the projectiles are often lead-based, and the targets are animals that will likely be ingested by people and/or scavenging wildlife. Medical radiography (lab-based polychromatic X-ray imaging instruments routinely used in hospitals and for dental exams) has been the most widespread and accepted method to reveal these fragments within thick, hydrated tissue sections. It is also deployed at some food banks to screen packages of donated game meat for lead contamination in the form of projectile fragments. We present the first synchrotron-based X-ray images of rifle and shotgun wounds in biological tissue from hunted wild game animals, and contrast them against medical radiographs. Micro- and nanoscale fragments, undetectable in medical radiographs, were directly observed within tissue for the first time and conclusively identified as lead using X-ray absorption and emission spectroscopies. The mass of just those lead fragments that were below the detection limit of medical radiography was quantified and found to exceed levels set by the US Centers for Disease Control and Prevention for protection of human health.