John Dudgeon

Heavy Metal in Children’s Tooth Enamel: Related to Autism and Disruptive Behaviors?

To examine possible links between neurotoxicant exposure and neuropsychological disorders and child behavior, relative concentrations of lead, mercury, and manganese were examined in prenatal and postnatal enamel regions of deciduous teeth from children with Autism Spectrum Disorders (ASDs), high levels of disruptive behavior (HDB), and typically developing (TD) children. Using laser ablation inductively coupled plasma mass spectrometry, we found no significant differences in levels of these neurotoxicants for children with ASDs compared with TD children, but there was marginal significance indicating that children with ASDs have lower manganese levels. No significant differences emerged between children with HDB and TD children. The current findings challenge the notion that perinatal heavy metal exposure is a major contributor to the development of ASDs and HDB.

A stable isotope (δ13C and δ15N) perspective on human diet on rapa nui (Easter Island) ca. AD 1400–1900

Ecological and environmental evidence suggests that Rapa Nui was among the most marginally habitable islands in Eastern Polynesia, with only a fraction of the biotic diversity found on archipelagos to the west, and capable of sustaining many fewer cultigens traditionally transported by Polynesian colonizers. However, archaeological evidence for human dietary adaptations under such restrictions is limited. Little is known about the particulars of the subsistence base and dietary changes on Rapa Nui that may be associated with a hypothesized late prehistoric decline in the quality and diversity of food sources. To better understand prehistoric Rapa Nui diet we examined stable carbon and nitrogen isotope compositions of human teeth along with archaeological faunal material thought to comprise the Rapa Nui food web. Our results indicate that contrary to previous zooarchaeological studies diet was predominantly terrestrial throughout the entire sequence of occupation, with reliance on rats, chickens and C3 plants. While a few individuals may have had access to higher trophic level marine resources, this is evident only later in time (generally post-AD 1600). A decline in (15)N through time was observed, and may be attributed to declines in available terrestrial proteins; however, presently we cannot rule out the effect of changing soil and plant baseline δ(15)N. Our results also suggest differential access to higher trophic level marine resources among contemporaneous populations, but more research is required to clarify this observation.

Investigating Biogenic Versus Diagenetic Trace Element Incorporation in Archaeological Mineralized Tissues with LA-ICP-MS

In this chapter, we develop a method employing combined SEM-EDS and LA-ICP-MS analysis of mineralized tissue (bone apatite) to quantify trace element concentrations. We apply this method to bone and tooth samples from the Kammenyi Ambar 5 cemetery (Russia) to determine whether a trace element signal resulting from working of Arsenical Bronze can be distinguished from post-burial uptake of trace elements. Using raster mapping of bone and tooth cross-sections, we demonstrate that while some elements show a pattern consistent with post-burial uptake, other elements including arsenic appear to reflect uptake related to life activities including Bronze working. We review mechanisms by which trace elements may find their way into bone and tooth structure to explain these differences in incorporation pathway.

LA-ICP-MS Analysis of Prehistoric Copper and Bronze Metalwork from Armenia

Analysis of prehistoric copper and bronze in the Caucasus was performed previously on thousands of objects with arc optical emission spectroscopy (OES). While arc OES is no longer widely used in archaeometry, LA-ICP-MS has shown great promise for isotopic and chemical analysis of ancient copper and bronze artifacts. In order to explore the effectiveness of LA-ICP-MS for the characterization of materials in a large group of ancient copper-based metalwork from the South Caucasus, we analyzed 48 metal artifacts from the Horom necropolis and 16 from the Karashamb necropolis, at Idaho State University’s Center for Archaeology, Materials and Applied Spectroscopy (CAMAS). These artifacts had been recovered from burials dating to the late second–early first millennium bc, a period noted for the use of a variety of copper alloy mixtures, including antimony bronze (which is very unusual at this early period in Europe and Asia). The metal artifacts from Horom had been previously analyzed by arc OES at the Institute of Archaeology and Ethnography in Yerevan, Armenia. This provided the opportunity to compare the performance of arc OES with LA-ICP-MS for analysis of variations in the use of copper alloys in ancient metal artifacts. In addition to LA-ICP-MS, EDS was used to analyze major elements, especially the proportion of copper in relation minor and trace elements that were measured with LA-ICP-MS. Besides unalloyed copper, the alloys detected by EDS and arc OES included mixtures with arsenic, tin, lead and antimony. More alloys were detected in the assemblage by LA-ICP-MS and EDS than with arc OES. This may be because copper levels were measured by EDS allowing the results for all elements to be normalized in proportion to copper. Normalization of results was therefore not possible with arc OES, which is another advantage of using LA-ICP-MS together with EDS.