Using and interpreting isotope data for source identification

Isotopes have been widely used for source identification since the early twentieth century. Recent advances in analytical techniques have increased the precision and the accuracy of isotope analysis. As a result, the use of isotopes has spread to several fields (e.g., ecology, food chemistry, archaeology, environmental health and pollution, and forensic sciences).This review examines the principal uses of stable-isotope analyses for tracing origins or sources, along with statistical methods employed for data interpretation, in recent papers (2007-09) dealing essentially with food authentication, ecology, environmental pollution and other applications, including geology, police forensics, hydrology and archaeometry. The main elements analyzed were H, C, N, O, S, Sr and Pb.For isotope-data interpretation, statistical methods appear to depend essentially on the field, the objectives of the study and the number of parameters. They were not often stated explicitly because the studies were exploratory and aimed primarily at assessing the relevance of the analytical techniques used to identify sources. We critically discuss the adequacy of these methods.