While lead was banned from waterfowl ammunition in the U.S. in 1991, the majority of people who hunt other types of game use lead ammunition. Upon impact, a lead bullet can fragment into tiny microparticles, too small to see with the naked eye or sense when eating. A deer processor in Pennsylvania who requested anonymity shared his first-hand experience. "Seventy-five percent of the time when I find a bullet in the carcass, I only find the base. I know the lead is all in the meat somewhere," he told EHN. Scientists have used X-rays to visualize and count sometimes hundreds of minute lead particles in hunted meat, and have detected high concentrations of lead in hunted carcasses using chemical analysis. Although the U.S. Food and Drug Administration does not recognize a safe limit for the amount of lead in meat, the European Commission set maximum levels at 0.1 parts per million (ppm). Concentrations of lead more than 100 times this limit have been detected in the meat of lead-shot carcasses as far as six inches from the entry wound. In 2009, biologists from the Minnesota Department of Natural Resources x-rayed deer and sheep carcasses that were shot with lead ammunition to make any lead fragments visible. They found some types of lead bullets fragmented more than others, and that fragmentation was more extensive when poorly-placed shots struck large bones. They also found that lead ammunition fired from high-powered rifles contaminated carcasses more than slower-moving lead slugs fired from shotguns.