He says a detection rate of only about 5 to 10 percent is typical when searching for protein residue on artifacts, but he's confident in those results. (discovermagazine.com)
Of this sample, 17 tools tested positive for protein residue, i.e. blood and other animal products. (sciencedaily.com)
This review reported that, though higher protein levels led to faster growth, the (supposed) benefit «could not be weighed against the adverse consequences» of excess protein residues in the blood and neurodevelopmental abnormalities. (babyreference.com)