The analysis of 17th-, 18th- and 19th-century ceramics from Port Royal, Jamaica for lead release : a study in archaeotoxicology

Abstract

The concern over lead poisoning in modern times has, in turn, influenced many archaeologists and historians to investigate the ways in which exposure to lead may have affected populations in the past. Researchers interested in past lead poisoning have primarily used historical records and skeletal analyses in attempting to study this problem, while artifactual analyses have been largely ignored. In investigating the potential for contributions to lead poisoning in past populations, however, artifacts have the potential to yield a great deal of information. There are many types of lead-containing artifacts, but lead-glazed ceramics were one of the most common historically. For this reason, lead-glazed ceramics were chosen for lead-release analysis. Initial tests on archaeologically-recovered sherds from Port Royal, Jamaica, indicated that substantial amounts of lead could be released by these ceramics. Experiments with ceramic tiles of equal glazed surface area demonstrated a predictable relationship between the volume of solution in which the tile was immersed and the glazed surface area. This relationship permitted the prediction of lead release for different volume/surface area ratios, which can be used to simulate different sized ceramic vessels, from a single sherd. Additional tests with solutions of different pH and with varying temperatures provided information on the effects of these variables. This information was used to devise a predictive strategy for estimating lead release according to different uses of ceramic vessels, such as cooking or storage of different foods. These tests provide the framework for lead release extrapolations from any lead-glazed sherd, as well as the basis for developing methods of testing other lead-based artifacts.