Elevated lead exposure in Roman occupants of Londinium: New evidence from the archaeological record

Abstract

The evolution of metallurgical practices over several millennia has resulted in human exposures to a diverse variety of toxic elements. These exposures were not just confined to the metalworkers, but in many cases broadly impacted the larger community and society. The role of lead in Roman civilization is particularly fascinating, where the available evidence of lead use in a myriad of applications by Roman civilization suggests the potential for elevated exposures. The present paper addresses the hypothesis that because of these practices, Roman occupants of ancient Londinium (43–410 ad) were exposed to levels of lead that far exceeded exposures in the preceding populations of Iron Age Britain (700 bc–43 ad). The elemental content and stable lead and strontium isotopic signatures of 30 femora from three Londinium cemeteries and radiocarbon‐dated representative burials were examined and the results then compared with 70 femora dating to the pre‐Roman Iron Age from the well‐known Iron Age hillfort of Danebury, Hampshire, and from three cemeteries in East Yorkshire. Extensive efforts were directed at the minimization of sediment and soil contamination, the assessment of contamination from burial artefacts and a careful review of the burial context of specimens. Data for lead and 20 additional trace and major elements were obtained by magnetic sector inductively coupled plasma mass spectrometry (ICPMS), after acid dissolution of pre‐cleaned bone cores. Lead isotope ratios in the bone core digests (and burial soils) were measured by multi‐collector ICPMS. It was found that concentrations of lead in the Roman/Londinium‐era femora were > 70‐fold greater than those from pre‐Roman populations. This was confirmed by femoral data obtained from the analysis of a pre‐Roman burial from the early first century bc found adjacent to the Southern Cemetery. Several major and trace element metrics for diagenesis demonstrate that levels of lead in the bone are robust indicators of human exposure during life. Lead isotope data for the Roman population are consistent with previously identified widespread lead pollution. The pre‐Roman populations contain lead isotopic compositions consistent with highly localized, minor sources of lead. Together, these data provide unequivocal confirmation that the Romans in Londinium were exposed to elevated lead levels. Elevated blood lead levels would have resulted, negatively affecting their health and possibly contributing to declining birth rates.