Release of lead from Renaissance lead-glazed ceramics from southern Denmark and northern Germany: implications from acetic acid etching experiments

Abstract

Lead-glazed potsherds from archaeological excavations at six Renaissance (1536–1660 CE) sites in southern Denmark and northern Germany have been subjected to etching experiments using 4 wt% acetic acid. The extracts of 45 sherds were analysed by Inductively Coupled Plasma Mass Spectrometry. At one site, the ducal hunting castle of Grøngaard, Pb levels in acid extracts from glazed dishes were so high (up to 29,000 µg Pb cm−2 day−1) that acute toxic effects likely occurred if the dishes were used for serving food containing vinegar. More moderate acid-etching Pb levels were found in dishes from other sites, but they still exceed the WHO critical level if used daily. Acetic acid etching experiments performed on pipkins (three-legged cooking pots with a handle) yielded somewhat lower Pb extract values, averaging ca. 25 µg Pb cm−2 day−1. Taking into account the widespread use of pipkins for cooking, they might easily have led to a higher weekly Pb intake than the use of the moderate-level dishes. The question remains whether such high levels of Pb exposure during meals led to injurious Pb intake. Prior skeletal analyses have shown that medieval to early modern individuals from the area, especially in towns, were exposed to Pb. While exposure could have come from various sources other than lead-glazed ceramics, such as cosmetics, paint, antibacterial ointments, and lead water pipes, widely distributed lead-glazed ceramics had the potential of being a main source of Pb. How the pottery was actually used is uncertain, and it certainly was not evenly distributed across all segments of society, but the etching experiment results suggest that severe poisonous effects could have resulted from the use of lead-glazed Renaissance ceramics.

Mapping bone microstructure trace element composition: Sr, Ba, Cu, and Pb in an early modern Danish skeleton

“…The correlation between Pb and Cu, the socioeconomic indicators, is not as strong as it is for Sr and Ba, the dietary markers (Figures 3 and 4). Much of the Pb exposure might have come from using lead-glazed pottery (Rasmussen et al, 2022). The use of everyday objects made from metal alloys containing Cu, such as cooking pots and pans, would have exposed people to Cu.…”

“…Lead-glazed pottery, for example, was commonly available at that time, especially in towns. Its use when storing, cooking, and serving food exposed people to high, even toxic, Pb levels (Rasmussen et al, 2022).…”

“…Exposure to Pb and Cu varied by residence location, with townsfolk incorporating more of these two elements in their bones than villagers (Rasmussen et al, 2015; Rasmussen, Delbey, et al, 2020; Rasmussen, Milner, Delbey, Skytte, Søvsø, et al, 2020). Much of the Pb presumably came from lead‐glazed pottery vessels, some of which would have resulted in dangerously high Pb exposure (Rasmussen et al, 2022). The origin of Cu exposure is not as well established, but utilitarian items such as metal pots and pans were likely sources (Rasmussen, Milner, Delbey, Skytte, Søvsø, et al, 2020).…”

Variation in Bioavailable Lead, Copper, and Strontium Concentrations in Human Skeletons from Medieval to Early Modern Denmark

“…Others are not, and some have outright toxic effects, including Pb. Centuries ago Pb poisoning was likely through the frequent use of the lead-glazed pottery that was widely available in Denmark (Rasmussen et al, 2022). Once ingested, metabolic processes determine what elements, and how much of them, are incorporated into various tissues, including bone.…”

“…But even people of low rank, notably servants in rich households, could have been exposed to Pb and Cu out of all proportion to their social position. In fact, high Pb concentrations in lead-glazed pottery, as seen through experiments with Danish Renaissance vessels, were likely a major source of food and liquid contamination (Rasmussen et al, 2022).…”