The mercury content of prehistoric fish

Seventeen samples of fish remains have been analyzed for mercury content by a neutron activation technique. Three samples were from Apple Creek, a Late Woodland site in central Illinois, which is dated shortly after A.D. 400. Five samples were from the Schultz site in Saginaw County, Michigan, a Middle Woodland location slightly older than Apple Creek. The remaining nine samples were from the pre‐Inca Chilca site located on the central coast of Peru. Freshwater species tested were Ictalurus punctatus (channel catfish), Pylodictis olivaris (flathead catfish), and Aplodinotus grunniens (drum). Five modern samples of these species from streams near Apple Creek were analyzed as a control. Peruvian salt water species have not yet been identified but are probably tuna and anchovy. Samples of the soil matrix in which the Chilca and Shultz specimens were found were also tested. Twelve of the prehistoric samples contained mercury in detectable quantities ranging from 0.014 to 9.463 ppm. Only one of the modern samples contained detectable mercury and neither soil sample had mercury in detectable amounts. The importance of archaeological data for establishing baselines for modern environmental evaluations is discussed. Implications of these data for modern disposal practices are considered.